… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
|
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9 | =head2 EXAMPLE PROGRAM |
|
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10 | |
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11 | // a single header file is required |
|
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12 | #include <ev.h> |
|
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13 | |
|
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14 | // every watcher type has its own typedef'd struct |
|
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15 | // with the name ev_<type> |
|
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16 | ev_io stdin_watcher; |
|
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17 | ev_timer timeout_watcher; |
|
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18 | |
|
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19 | // all watcher callbacks have a similar signature |
|
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20 | // this callback is called when data is readable on stdin |
|
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21 | static void |
|
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22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
|
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23 | { |
|
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24 | puts ("stdin ready"); |
|
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25 | // for one-shot events, one must manually stop the watcher |
|
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26 | // with its corresponding stop function. |
|
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27 | ev_io_stop (EV_A_ w); |
|
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28 | |
|
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29 | // this causes all nested ev_loop's to stop iterating |
|
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30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
|
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31 | } |
|
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32 | |
|
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33 | // another callback, this time for a time-out |
|
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34 | static void |
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35 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
|
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36 | { |
|
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37 | puts ("timeout"); |
|
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38 | // this causes the innermost ev_loop to stop iterating |
|
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39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
|
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40 | } |
|
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41 | |
|
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42 | int |
|
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43 | main (void) |
|
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44 | { |
|
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45 | // use the default event loop unless you have special needs |
|
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46 | struct ev_loop *loop = ev_default_loop (0); |
|
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47 | |
|
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48 | // initialise an io watcher, then start it |
|
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49 | // this one will watch for stdin to become readable |
|
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50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
|
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51 | ev_io_start (loop, &stdin_watcher); |
|
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52 | |
|
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53 | // initialise a timer watcher, then start it |
|
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54 | // simple non-repeating 5.5 second timeout |
|
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55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
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56 | ev_timer_start (loop, &timeout_watcher); |
|
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57 | |
|
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58 | // now wait for events to arrive |
|
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59 | ev_loop (loop, 0); |
|
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60 | |
|
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61 | // unloop was called, so exit |
|
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62 | return 0; |
|
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63 | } |
|
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64 | |
9 | =head1 DESCRIPTION |
65 | =head1 DESCRIPTION |
10 | |
66 | |
|
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67 | The newest version of this document is also available as an html-formatted |
|
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68 | web page you might find easier to navigate when reading it for the first |
|
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69 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
|
|
70 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
71 | Libev is an event loop: you register interest in certain events (such as a |
12 | file descriptor being readable or a timeout occuring), and it will manage |
72 | file descriptor being readable or a timeout occurring), and it will manage |
13 | these event sources and provide your program with events. |
73 | these event sources and provide your program with events. |
14 | |
74 | |
15 | To do this, it must take more or less complete control over your process |
75 | To do this, it must take more or less complete control over your process |
16 | (or thread) by executing the I<event loop> handler, and will then |
76 | (or thread) by executing the I<event loop> handler, and will then |
17 | communicate events via a callback mechanism. |
77 | communicate events via a callback mechanism. |
… | |
… | |
19 | You register interest in certain events by registering so-called I<event |
79 | You register interest in certain events by registering so-called I<event |
20 | watchers>, which are relatively small C structures you initialise with the |
80 | watchers>, which are relatively small C structures you initialise with the |
21 | details of the event, and then hand it over to libev by I<starting> the |
81 | details of the event, and then hand it over to libev by I<starting> the |
22 | watcher. |
82 | watcher. |
23 | |
83 | |
24 | =head1 FEATURES |
84 | =head2 FEATURES |
25 | |
85 | |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
86 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
87 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
28 | timers with customised rescheduling, signal events, process status change |
88 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
89 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
90 | with customised rescheduling (C<ev_periodic>), synchronous signals |
|
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91 | (C<ev_signal>), process status change events (C<ev_child>), and event |
|
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92 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
|
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93 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
|
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94 | file watchers (C<ev_stat>) and even limited support for fork events |
|
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95 | (C<ev_fork>). |
|
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96 | |
|
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97 | It also is quite fast (see this |
31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
98 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
32 | it to libevent for example). |
99 | for example). |
33 | |
100 | |
34 | =head1 CONVENTIONS |
101 | =head2 CONVENTIONS |
35 | |
102 | |
36 | Libev is very configurable. In this manual the default configuration |
103 | Libev is very configurable. In this manual the default (and most common) |
37 | will be described, which supports multiple event loops. For more info |
104 | configuration will be described, which supports multiple event loops. For |
38 | about various configuration options please have a look at the file |
105 | more info about various configuration options please have a look at |
39 | F<README.embed> in the libev distribution. If libev was configured without |
106 | B<EMBED> section in this manual. If libev was configured without support |
40 | support for multiple event loops, then all functions taking an initial |
107 | for multiple event loops, then all functions taking an initial argument of |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
108 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
42 | will not have this argument. |
109 | this argument. |
43 | |
110 | |
44 | =head1 TIME REPRESENTATION |
111 | =head2 TIME REPRESENTATION |
45 | |
112 | |
46 | Libev represents time as a single floating point number, representing the |
113 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the C<double> type in C, and when you need to do any calculations on |
117 | to the C<double> type in C, and when you need to do any calculations on |
51 | it, you should treat it as such. |
118 | it, you should treat it as some floatingpoint value. Unlike the name |
52 | |
119 | component C<stamp> might indicate, it is also used for time differences |
|
|
120 | throughout libev. |
53 | |
121 | |
54 | =head1 GLOBAL FUNCTIONS |
122 | =head1 GLOBAL FUNCTIONS |
55 | |
123 | |
56 | These functions can be called anytime, even before initialising the |
124 | These functions can be called anytime, even before initialising the |
57 | library in any way. |
125 | library in any way. |
… | |
… | |
62 | |
130 | |
63 | Returns the current time as libev would use it. Please note that the |
131 | Returns the current time as libev would use it. Please note that the |
64 | C<ev_now> function is usually faster and also often returns the timestamp |
132 | C<ev_now> function is usually faster and also often returns the timestamp |
65 | you actually want to know. |
133 | you actually want to know. |
66 | |
134 | |
|
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135 | =item ev_sleep (ev_tstamp interval) |
|
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136 | |
|
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137 | Sleep for the given interval: The current thread will be blocked until |
|
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138 | either it is interrupted or the given time interval has passed. Basically |
|
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139 | this is a subsecond-resolution C<sleep ()>. |
|
|
140 | |
67 | =item int ev_version_major () |
141 | =item int ev_version_major () |
68 | |
142 | |
69 | =item int ev_version_minor () |
143 | =item int ev_version_minor () |
70 | |
144 | |
71 | You can find out the major and minor version numbers of the library |
145 | You can find out the major and minor ABI version numbers of the library |
72 | you linked against by calling the functions C<ev_version_major> and |
146 | you linked against by calling the functions C<ev_version_major> and |
73 | C<ev_version_minor>. If you want, you can compare against the global |
147 | C<ev_version_minor>. If you want, you can compare against the global |
74 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
148 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
75 | version of the library your program was compiled against. |
149 | version of the library your program was compiled against. |
76 | |
150 | |
|
|
151 | These version numbers refer to the ABI version of the library, not the |
|
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152 | release version. |
|
|
153 | |
77 | Usually, it's a good idea to terminate if the major versions mismatch, |
154 | Usually, it's a good idea to terminate if the major versions mismatch, |
78 | as this indicates an incompatible change. Minor versions are usually |
155 | as this indicates an incompatible change. Minor versions are usually |
79 | compatible to older versions, so a larger minor version alone is usually |
156 | compatible to older versions, so a larger minor version alone is usually |
80 | not a problem. |
157 | not a problem. |
81 | |
158 | |
82 | Example: make sure we haven't accidentally been linked against the wrong |
159 | Example: Make sure we haven't accidentally been linked against the wrong |
83 | version: |
160 | version. |
84 | |
161 | |
85 | assert (("libev version mismatch", |
162 | assert (("libev version mismatch", |
86 | ev_version_major () == EV_VERSION_MAJOR |
163 | ev_version_major () == EV_VERSION_MAJOR |
87 | && ev_version_minor () >= EV_VERSION_MINOR)); |
164 | && ev_version_minor () >= EV_VERSION_MINOR)); |
88 | |
165 | |
… | |
… | |
118 | |
195 | |
119 | See the description of C<ev_embed> watchers for more info. |
196 | See the description of C<ev_embed> watchers for more info. |
120 | |
197 | |
121 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
198 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
122 | |
199 | |
123 | Sets the allocation function to use (the prototype is similar to the |
200 | Sets the allocation function to use (the prototype is similar - the |
124 | realloc C function, the semantics are identical). It is used to allocate |
201 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
125 | and free memory (no surprises here). If it returns zero when memory |
202 | used to allocate and free memory (no surprises here). If it returns zero |
126 | needs to be allocated, the library might abort or take some potentially |
203 | when memory needs to be allocated (C<size != 0>), the library might abort |
127 | destructive action. The default is your system realloc function. |
204 | or take some potentially destructive action. |
|
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205 | |
|
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206 | Since some systems (at least OpenBSD and Darwin) fail to implement |
|
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207 | correct C<realloc> semantics, libev will use a wrapper around the system |
|
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208 | C<realloc> and C<free> functions by default. |
128 | |
209 | |
129 | You could override this function in high-availability programs to, say, |
210 | You could override this function in high-availability programs to, say, |
130 | free some memory if it cannot allocate memory, to use a special allocator, |
211 | free some memory if it cannot allocate memory, to use a special allocator, |
131 | or even to sleep a while and retry until some memory is available. |
212 | or even to sleep a while and retry until some memory is available. |
132 | |
213 | |
133 | Example: replace the libev allocator with one that waits a bit and then |
214 | Example: Replace the libev allocator with one that waits a bit and then |
134 | retries: better than mine). |
215 | retries (example requires a standards-compliant C<realloc>). |
135 | |
216 | |
136 | static void * |
217 | static void * |
137 | persistent_realloc (void *ptr, long size) |
218 | persistent_realloc (void *ptr, size_t size) |
138 | { |
219 | { |
139 | for (;;) |
220 | for (;;) |
140 | { |
221 | { |
141 | void *newptr = realloc (ptr, size); |
222 | void *newptr = realloc (ptr, size); |
142 | |
223 | |
… | |
… | |
158 | callback is set, then libev will expect it to remedy the sitution, no |
239 | callback is set, then libev will expect it to remedy the sitution, no |
159 | matter what, when it returns. That is, libev will generally retry the |
240 | matter what, when it returns. That is, libev will generally retry the |
160 | requested operation, or, if the condition doesn't go away, do bad stuff |
241 | requested operation, or, if the condition doesn't go away, do bad stuff |
161 | (such as abort). |
242 | (such as abort). |
162 | |
243 | |
163 | Example: do the same thing as libev does internally: |
244 | Example: This is basically the same thing that libev does internally, too. |
164 | |
245 | |
165 | static void |
246 | static void |
166 | fatal_error (const char *msg) |
247 | fatal_error (const char *msg) |
167 | { |
248 | { |
168 | perror (msg); |
249 | perror (msg); |
… | |
… | |
178 | |
259 | |
179 | An event loop is described by a C<struct ev_loop *>. The library knows two |
260 | An event loop is described by a C<struct ev_loop *>. The library knows two |
180 | types of such loops, the I<default> loop, which supports signals and child |
261 | types of such loops, the I<default> loop, which supports signals and child |
181 | events, and dynamically created loops which do not. |
262 | events, and dynamically created loops which do not. |
182 | |
263 | |
183 | If you use threads, a common model is to run the default event loop |
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184 | in your main thread (or in a separate thread) and for each thread you |
|
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185 | create, you also create another event loop. Libev itself does no locking |
|
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186 | whatsoever, so if you mix calls to the same event loop in different |
|
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187 | threads, make sure you lock (this is usually a bad idea, though, even if |
|
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188 | done correctly, because it's hideous and inefficient). |
|
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189 | |
|
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190 | =over 4 |
264 | =over 4 |
191 | |
265 | |
192 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
266 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
193 | |
267 | |
194 | This will initialise the default event loop if it hasn't been initialised |
268 | This will initialise the default event loop if it hasn't been initialised |
… | |
… | |
196 | false. If it already was initialised it simply returns it (and ignores the |
270 | false. If it already was initialised it simply returns it (and ignores the |
197 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
271 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
198 | |
272 | |
199 | If you don't know what event loop to use, use the one returned from this |
273 | If you don't know what event loop to use, use the one returned from this |
200 | function. |
274 | function. |
|
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275 | |
|
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276 | Note that this function is I<not> thread-safe, so if you want to use it |
|
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277 | from multiple threads, you have to lock (note also that this is unlikely, |
|
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278 | as loops cannot bes hared easily between threads anyway). |
|
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279 | |
|
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280 | The default loop is the only loop that can handle C<ev_signal> and |
|
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281 | C<ev_child> watchers, and to do this, it always registers a handler |
|
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282 | for C<SIGCHLD>. If this is a problem for your app you can either |
|
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283 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
|
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284 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
|
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285 | C<ev_default_init>. |
201 | |
286 | |
202 | The flags argument can be used to specify special behaviour or specific |
287 | The flags argument can be used to specify special behaviour or specific |
203 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
288 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
204 | |
289 | |
205 | The following flags are supported: |
290 | The following flags are supported: |
… | |
… | |
218 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
303 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
219 | override the flags completely if it is found in the environment. This is |
304 | override the flags completely if it is found in the environment. This is |
220 | useful to try out specific backends to test their performance, or to work |
305 | useful to try out specific backends to test their performance, or to work |
221 | around bugs. |
306 | around bugs. |
222 | |
307 | |
|
|
308 | =item C<EVFLAG_FORKCHECK> |
|
|
309 | |
|
|
310 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
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311 | a fork, you can also make libev check for a fork in each iteration by |
|
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312 | enabling this flag. |
|
|
313 | |
|
|
314 | This works by calling C<getpid ()> on every iteration of the loop, |
|
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315 | and thus this might slow down your event loop if you do a lot of loop |
|
|
316 | iterations and little real work, but is usually not noticeable (on my |
|
|
317 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
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318 | without a syscall and thus I<very> fast, but my GNU/Linux system also has |
|
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319 | C<pthread_atfork> which is even faster). |
|
|
320 | |
|
|
321 | The big advantage of this flag is that you can forget about fork (and |
|
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322 | forget about forgetting to tell libev about forking) when you use this |
|
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323 | flag. |
|
|
324 | |
|
|
325 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
326 | environment variable. |
|
|
327 | |
223 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
328 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
224 | |
329 | |
225 | This is your standard select(2) backend. Not I<completely> standard, as |
330 | This is your standard select(2) backend. Not I<completely> standard, as |
226 | libev tries to roll its own fd_set with no limits on the number of fds, |
331 | libev tries to roll its own fd_set with no limits on the number of fds, |
227 | but if that fails, expect a fairly low limit on the number of fds when |
332 | but if that fails, expect a fairly low limit on the number of fds when |
228 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
333 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
229 | the fastest backend for a low number of fds. |
334 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
335 | |
|
|
336 | To get good performance out of this backend you need a high amount of |
|
|
337 | parallelity (most of the file descriptors should be busy). If you are |
|
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338 | writing a server, you should C<accept ()> in a loop to accept as many |
|
|
339 | connections as possible during one iteration. You might also want to have |
|
|
340 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
|
|
341 | readyness notifications you get per iteration. |
230 | |
342 | |
231 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
343 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
232 | |
344 | |
233 | And this is your standard poll(2) backend. It's more complicated than |
345 | And this is your standard poll(2) backend. It's more complicated |
234 | select, but handles sparse fds better and has no artificial limit on the |
346 | than select, but handles sparse fds better and has no artificial |
235 | number of fds you can use (except it will slow down considerably with a |
347 | limit on the number of fds you can use (except it will slow down |
236 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
348 | considerably with a lot of inactive fds). It scales similarly to select, |
|
|
349 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
|
|
350 | performance tips. |
237 | |
351 | |
238 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
352 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
239 | |
353 | |
240 | For few fds, this backend is a bit little slower than poll and select, |
354 | For few fds, this backend is a bit little slower than poll and select, |
241 | but it scales phenomenally better. While poll and select usually scale like |
355 | but it scales phenomenally better. While poll and select usually scale |
242 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
356 | like O(total_fds) where n is the total number of fds (or the highest fd), |
243 | either O(1) or O(active_fds). |
357 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
|
|
358 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
|
359 | cases and requiring a syscall per fd change, no fork support and bad |
|
|
360 | support for dup. |
244 | |
361 | |
245 | While stopping and starting an I/O watcher in the same iteration will |
362 | While stopping, setting and starting an I/O watcher in the same iteration |
246 | result in some caching, there is still a syscall per such incident |
363 | will result in some caching, there is still a syscall per such incident |
247 | (because the fd could point to a different file description now), so its |
364 | (because the fd could point to a different file description now), so its |
248 | best to avoid that. Also, dup()ed file descriptors might not work very |
365 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
249 | well if you register events for both fds. |
366 | very well if you register events for both fds. |
250 | |
367 | |
251 | Please note that epoll sometimes generates spurious notifications, so you |
368 | Please note that epoll sometimes generates spurious notifications, so you |
252 | need to use non-blocking I/O or other means to avoid blocking when no data |
369 | need to use non-blocking I/O or other means to avoid blocking when no data |
253 | (or space) is available. |
370 | (or space) is available. |
254 | |
371 | |
|
|
372 | Best performance from this backend is achieved by not unregistering all |
|
|
373 | watchers for a file descriptor until it has been closed, if possible, i.e. |
|
|
374 | keep at least one watcher active per fd at all times. |
|
|
375 | |
|
|
376 | While nominally embeddeble in other event loops, this feature is broken in |
|
|
377 | all kernel versions tested so far. |
|
|
378 | |
255 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
379 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
256 | |
380 | |
257 | Kqueue deserves special mention, as at the time of this writing, it |
381 | Kqueue deserves special mention, as at the time of this writing, it |
258 | was broken on all BSDs except NetBSD (usually it doesn't work with |
382 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
259 | anything but sockets and pipes, except on Darwin, where of course its |
383 | with anything but sockets and pipes, except on Darwin, where of course |
260 | completely useless). For this reason its not being "autodetected" |
384 | it's completely useless). For this reason it's not being "autodetected" |
261 | unless you explicitly specify it explicitly in the flags (i.e. using |
385 | unless you explicitly specify it explicitly in the flags (i.e. using |
262 | C<EVBACKEND_KQUEUE>). |
386 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
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387 | system like NetBSD. |
|
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388 | |
|
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389 | You still can embed kqueue into a normal poll or select backend and use it |
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390 | only for sockets (after having made sure that sockets work with kqueue on |
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391 | the target platform). See C<ev_embed> watchers for more info. |
263 | |
392 | |
264 | It scales in the same way as the epoll backend, but the interface to the |
393 | It scales in the same way as the epoll backend, but the interface to the |
265 | kernel is more efficient (which says nothing about its actual speed, of |
394 | kernel is more efficient (which says nothing about its actual speed, of |
266 | course). While starting and stopping an I/O watcher does not cause an |
395 | course). While stopping, setting and starting an I/O watcher does never |
267 | extra syscall as with epoll, it still adds up to four event changes per |
396 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
268 | incident, so its best to avoid that. |
397 | two event changes per incident, support for C<fork ()> is very bad and it |
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398 | drops fds silently in similarly hard-to-detect cases. |
|
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399 | |
|
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400 | This backend usually performs well under most conditions. |
|
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401 | |
|
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402 | While nominally embeddable in other event loops, this doesn't work |
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403 | everywhere, so you might need to test for this. And since it is broken |
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404 | almost everywhere, you should only use it when you have a lot of sockets |
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405 | (for which it usually works), by embedding it into another event loop |
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406 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
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407 | sockets. |
269 | |
408 | |
270 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
409 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
271 | |
410 | |
272 | This is not implemented yet (and might never be). |
411 | This is not implemented yet (and might never be, unless you send me an |
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412 | implementation). According to reports, C</dev/poll> only supports sockets |
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413 | and is not embeddable, which would limit the usefulness of this backend |
|
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414 | immensely. |
273 | |
415 | |
274 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
416 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
275 | |
417 | |
276 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
418 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
277 | it's really slow, but it still scales very well (O(active_fds)). |
419 | it's really slow, but it still scales very well (O(active_fds)). |
278 | |
420 | |
279 | Please note that solaris ports can result in a lot of spurious |
421 | Please note that solaris event ports can deliver a lot of spurious |
280 | notifications, so you need to use non-blocking I/O or other means to avoid |
422 | notifications, so you need to use non-blocking I/O or other means to avoid |
281 | blocking when no data (or space) is available. |
423 | blocking when no data (or space) is available. |
|
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424 | |
|
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425 | While this backend scales well, it requires one system call per active |
|
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426 | file descriptor per loop iteration. For small and medium numbers of file |
|
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427 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
|
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428 | might perform better. |
|
|
429 | |
|
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430 | On the positive side, ignoring the spurious readyness notifications, this |
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431 | backend actually performed to specification in all tests and is fully |
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432 | embeddable, which is a rare feat among the OS-specific backends. |
282 | |
433 | |
283 | =item C<EVBACKEND_ALL> |
434 | =item C<EVBACKEND_ALL> |
284 | |
435 | |
285 | Try all backends (even potentially broken ones that wouldn't be tried |
436 | Try all backends (even potentially broken ones that wouldn't be tried |
286 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
437 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
287 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
438 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
288 | |
439 | |
|
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440 | It is definitely not recommended to use this flag. |
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441 | |
289 | =back |
442 | =back |
290 | |
443 | |
291 | If one or more of these are ored into the flags value, then only these |
444 | If one or more of these are ored into the flags value, then only these |
292 | backends will be tried (in the reverse order as given here). If none are |
445 | backends will be tried (in the reverse order as listed here). If none are |
293 | specified, most compiled-in backend will be tried, usually in reverse |
446 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
294 | order of their flag values :) |
|
|
295 | |
447 | |
296 | The most typical usage is like this: |
448 | The most typical usage is like this: |
297 | |
449 | |
298 | if (!ev_default_loop (0)) |
450 | if (!ev_default_loop (0)) |
299 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
451 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
314 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
466 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
315 | always distinct from the default loop. Unlike the default loop, it cannot |
467 | always distinct from the default loop. Unlike the default loop, it cannot |
316 | handle signal and child watchers, and attempts to do so will be greeted by |
468 | handle signal and child watchers, and attempts to do so will be greeted by |
317 | undefined behaviour (or a failed assertion if assertions are enabled). |
469 | undefined behaviour (or a failed assertion if assertions are enabled). |
318 | |
470 | |
|
|
471 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
472 | libev with threads is indeed to create one loop per thread, and using the |
|
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473 | default loop in the "main" or "initial" thread. |
|
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474 | |
319 | Example: try to create a event loop that uses epoll and nothing else. |
475 | Example: Try to create a event loop that uses epoll and nothing else. |
320 | |
476 | |
321 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
477 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
322 | if (!epoller) |
478 | if (!epoller) |
323 | fatal ("no epoll found here, maybe it hides under your chair"); |
479 | fatal ("no epoll found here, maybe it hides under your chair"); |
324 | |
480 | |
… | |
… | |
327 | Destroys the default loop again (frees all memory and kernel state |
483 | Destroys the default loop again (frees all memory and kernel state |
328 | etc.). None of the active event watchers will be stopped in the normal |
484 | etc.). None of the active event watchers will be stopped in the normal |
329 | sense, so e.g. C<ev_is_active> might still return true. It is your |
485 | sense, so e.g. C<ev_is_active> might still return true. It is your |
330 | responsibility to either stop all watchers cleanly yoursef I<before> |
486 | responsibility to either stop all watchers cleanly yoursef I<before> |
331 | calling this function, or cope with the fact afterwards (which is usually |
487 | calling this function, or cope with the fact afterwards (which is usually |
332 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
488 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
333 | for example). |
489 | for example). |
|
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490 | |
|
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491 | Note that certain global state, such as signal state, will not be freed by |
|
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492 | this function, and related watchers (such as signal and child watchers) |
|
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493 | would need to be stopped manually. |
|
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494 | |
|
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495 | In general it is not advisable to call this function except in the |
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496 | rare occasion where you really need to free e.g. the signal handling |
|
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497 | pipe fds. If you need dynamically allocated loops it is better to use |
|
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498 | C<ev_loop_new> and C<ev_loop_destroy>). |
334 | |
499 | |
335 | =item ev_loop_destroy (loop) |
500 | =item ev_loop_destroy (loop) |
336 | |
501 | |
337 | Like C<ev_default_destroy>, but destroys an event loop created by an |
502 | Like C<ev_default_destroy>, but destroys an event loop created by an |
338 | earlier call to C<ev_loop_new>. |
503 | earlier call to C<ev_loop_new>. |
339 | |
504 | |
340 | =item ev_default_fork () |
505 | =item ev_default_fork () |
341 | |
506 | |
|
|
507 | This function sets a flag that causes subsequent C<ev_loop> iterations |
342 | This function reinitialises the kernel state for backends that have |
508 | to reinitialise the kernel state for backends that have one. Despite the |
343 | one. Despite the name, you can call it anytime, but it makes most sense |
509 | name, you can call it anytime, but it makes most sense after forking, in |
344 | after forking, in either the parent or child process (or both, but that |
510 | the child process (or both child and parent, but that again makes little |
345 | again makes little sense). |
511 | sense). You I<must> call it in the child before using any of the libev |
|
|
512 | functions, and it will only take effect at the next C<ev_loop> iteration. |
346 | |
513 | |
347 | You I<must> call this function in the child process after forking if and |
514 | On the other hand, you only need to call this function in the child |
348 | only if you want to use the event library in both processes. If you just |
515 | process if and only if you want to use the event library in the child. If |
349 | fork+exec, you don't have to call it. |
516 | you just fork+exec, you don't have to call it at all. |
350 | |
517 | |
351 | The function itself is quite fast and it's usually not a problem to call |
518 | The function itself is quite fast and it's usually not a problem to call |
352 | it just in case after a fork. To make this easy, the function will fit in |
519 | it just in case after a fork. To make this easy, the function will fit in |
353 | quite nicely into a call to C<pthread_atfork>: |
520 | quite nicely into a call to C<pthread_atfork>: |
354 | |
521 | |
355 | pthread_atfork (0, 0, ev_default_fork); |
522 | pthread_atfork (0, 0, ev_default_fork); |
356 | |
523 | |
357 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
358 | without calling this function, so if you force one of those backends you |
|
|
359 | do not need to care. |
|
|
360 | |
|
|
361 | =item ev_loop_fork (loop) |
524 | =item ev_loop_fork (loop) |
362 | |
525 | |
363 | Like C<ev_default_fork>, but acts on an event loop created by |
526 | Like C<ev_default_fork>, but acts on an event loop created by |
364 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
527 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
365 | after fork, and how you do this is entirely your own problem. |
528 | after fork, and how you do this is entirely your own problem. |
|
|
529 | |
|
|
530 | =item int ev_is_default_loop (loop) |
|
|
531 | |
|
|
532 | Returns true when the given loop actually is the default loop, false otherwise. |
|
|
533 | |
|
|
534 | =item unsigned int ev_loop_count (loop) |
|
|
535 | |
|
|
536 | Returns the count of loop iterations for the loop, which is identical to |
|
|
537 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
538 | happily wraps around with enough iterations. |
|
|
539 | |
|
|
540 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
541 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
542 | C<ev_prepare> and C<ev_check> calls. |
366 | |
543 | |
367 | =item unsigned int ev_backend (loop) |
544 | =item unsigned int ev_backend (loop) |
368 | |
545 | |
369 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
546 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
370 | use. |
547 | use. |
… | |
… | |
373 | |
550 | |
374 | Returns the current "event loop time", which is the time the event loop |
551 | Returns the current "event loop time", which is the time the event loop |
375 | received events and started processing them. This timestamp does not |
552 | received events and started processing them. This timestamp does not |
376 | change as long as callbacks are being processed, and this is also the base |
553 | change as long as callbacks are being processed, and this is also the base |
377 | time used for relative timers. You can treat it as the timestamp of the |
554 | time used for relative timers. You can treat it as the timestamp of the |
378 | event occuring (or more correctly, libev finding out about it). |
555 | event occurring (or more correctly, libev finding out about it). |
379 | |
556 | |
380 | =item ev_loop (loop, int flags) |
557 | =item ev_loop (loop, int flags) |
381 | |
558 | |
382 | Finally, this is it, the event handler. This function usually is called |
559 | Finally, this is it, the event handler. This function usually is called |
383 | after you initialised all your watchers and you want to start handling |
560 | after you initialised all your watchers and you want to start handling |
… | |
… | |
404 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
581 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
405 | usually a better approach for this kind of thing. |
582 | usually a better approach for this kind of thing. |
406 | |
583 | |
407 | Here are the gory details of what C<ev_loop> does: |
584 | Here are the gory details of what C<ev_loop> does: |
408 | |
585 | |
409 | * If there are no active watchers (reference count is zero), return. |
586 | - Before the first iteration, call any pending watchers. |
410 | - Queue prepare watchers and then call all outstanding watchers. |
587 | * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
588 | - If a fork was detected, queue and call all fork watchers. |
|
|
589 | - Queue and call all prepare watchers. |
411 | - If we have been forked, recreate the kernel state. |
590 | - If we have been forked, recreate the kernel state. |
412 | - Update the kernel state with all outstanding changes. |
591 | - Update the kernel state with all outstanding changes. |
413 | - Update the "event loop time". |
592 | - Update the "event loop time". |
414 | - Calculate for how long to block. |
593 | - Calculate for how long to sleep or block, if at all |
|
|
594 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
595 | any active watchers at all will result in not sleeping). |
|
|
596 | - Sleep if the I/O and timer collect interval say so. |
415 | - Block the process, waiting for any events. |
597 | - Block the process, waiting for any events. |
416 | - Queue all outstanding I/O (fd) events. |
598 | - Queue all outstanding I/O (fd) events. |
417 | - Update the "event loop time" and do time jump handling. |
599 | - Update the "event loop time" and do time jump handling. |
418 | - Queue all outstanding timers. |
600 | - Queue all outstanding timers. |
419 | - Queue all outstanding periodics. |
601 | - Queue all outstanding periodics. |
420 | - If no events are pending now, queue all idle watchers. |
602 | - If no events are pending now, queue all idle watchers. |
421 | - Queue all check watchers. |
603 | - Queue all check watchers. |
422 | - Call all queued watchers in reverse order (i.e. check watchers first). |
604 | - Call all queued watchers in reverse order (i.e. check watchers first). |
423 | Signals and child watchers are implemented as I/O watchers, and will |
605 | Signals and child watchers are implemented as I/O watchers, and will |
424 | be handled here by queueing them when their watcher gets executed. |
606 | be handled here by queueing them when their watcher gets executed. |
425 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
607 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
426 | were used, return, otherwise continue with step *. |
608 | were used, or there are no active watchers, return, otherwise |
|
|
609 | continue with step *. |
427 | |
610 | |
428 | Example: queue some jobs and then loop until no events are outsanding |
611 | Example: Queue some jobs and then loop until no events are outstanding |
429 | anymore. |
612 | anymore. |
430 | |
613 | |
431 | ... queue jobs here, make sure they register event watchers as long |
614 | ... queue jobs here, make sure they register event watchers as long |
432 | ... as they still have work to do (even an idle watcher will do..) |
615 | ... as they still have work to do (even an idle watcher will do..) |
433 | ev_loop (my_loop, 0); |
616 | ev_loop (my_loop, 0); |
… | |
… | |
437 | |
620 | |
438 | Can be used to make a call to C<ev_loop> return early (but only after it |
621 | Can be used to make a call to C<ev_loop> return early (but only after it |
439 | has processed all outstanding events). The C<how> argument must be either |
622 | has processed all outstanding events). The C<how> argument must be either |
440 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
623 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
441 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
624 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
625 | |
|
|
626 | This "unloop state" will be cleared when entering C<ev_loop> again. |
442 | |
627 | |
443 | =item ev_ref (loop) |
628 | =item ev_ref (loop) |
444 | |
629 | |
445 | =item ev_unref (loop) |
630 | =item ev_unref (loop) |
446 | |
631 | |
… | |
… | |
451 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
636 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
452 | example, libev itself uses this for its internal signal pipe: It is not |
637 | example, libev itself uses this for its internal signal pipe: It is not |
453 | visible to the libev user and should not keep C<ev_loop> from exiting if |
638 | visible to the libev user and should not keep C<ev_loop> from exiting if |
454 | no event watchers registered by it are active. It is also an excellent |
639 | no event watchers registered by it are active. It is also an excellent |
455 | way to do this for generic recurring timers or from within third-party |
640 | way to do this for generic recurring timers or from within third-party |
456 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
641 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
642 | (but only if the watcher wasn't active before, or was active before, |
|
|
643 | respectively). |
457 | |
644 | |
458 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
645 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
459 | running when nothing else is active. |
646 | running when nothing else is active. |
460 | |
647 | |
461 | struct dv_signal exitsig; |
648 | struct ev_signal exitsig; |
462 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
649 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
463 | ev_signal_start (myloop, &exitsig); |
650 | ev_signal_start (loop, &exitsig); |
464 | evf_unref (myloop); |
651 | evf_unref (loop); |
465 | |
652 | |
466 | Example: for some weird reason, unregister the above signal handler again. |
653 | Example: For some weird reason, unregister the above signal handler again. |
467 | |
654 | |
468 | ev_ref (myloop); |
655 | ev_ref (loop); |
469 | ev_signal_stop (myloop, &exitsig); |
656 | ev_signal_stop (loop, &exitsig); |
|
|
657 | |
|
|
658 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
659 | |
|
|
660 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
661 | |
|
|
662 | These advanced functions influence the time that libev will spend waiting |
|
|
663 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
664 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
665 | |
|
|
666 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
667 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
668 | increase efficiency of loop iterations. |
|
|
669 | |
|
|
670 | The background is that sometimes your program runs just fast enough to |
|
|
671 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
672 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
673 | events, especially with backends like C<select ()> which have a high |
|
|
674 | overhead for the actual polling but can deliver many events at once. |
|
|
675 | |
|
|
676 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
677 | time collecting I/O events, so you can handle more events per iteration, |
|
|
678 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
679 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
680 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
681 | |
|
|
682 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
683 | to spend more time collecting timeouts, at the expense of increased |
|
|
684 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
685 | will not be affected. Setting this to a non-null value will not introduce |
|
|
686 | any overhead in libev. |
|
|
687 | |
|
|
688 | Many (busy) programs can usually benefit by setting the io collect |
|
|
689 | interval to a value near C<0.1> or so, which is often enough for |
|
|
690 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
691 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
692 | as this approsaches the timing granularity of most systems. |
470 | |
693 | |
471 | =back |
694 | =back |
472 | |
695 | |
473 | |
696 | |
474 | =head1 ANATOMY OF A WATCHER |
697 | =head1 ANATOMY OF A WATCHER |
… | |
… | |
544 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
767 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
545 | |
768 | |
546 | =item C<EV_CHILD> |
769 | =item C<EV_CHILD> |
547 | |
770 | |
548 | The pid specified in the C<ev_child> watcher has received a status change. |
771 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
772 | |
|
|
773 | =item C<EV_STAT> |
|
|
774 | |
|
|
775 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
549 | |
776 | |
550 | =item C<EV_IDLE> |
777 | =item C<EV_IDLE> |
551 | |
778 | |
552 | The C<ev_idle> watcher has determined that you have nothing better to do. |
779 | The C<ev_idle> watcher has determined that you have nothing better to do. |
553 | |
780 | |
… | |
… | |
561 | received events. Callbacks of both watcher types can start and stop as |
788 | received events. Callbacks of both watcher types can start and stop as |
562 | many watchers as they want, and all of them will be taken into account |
789 | many watchers as they want, and all of them will be taken into account |
563 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
790 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
564 | C<ev_loop> from blocking). |
791 | C<ev_loop> from blocking). |
565 | |
792 | |
|
|
793 | =item C<EV_EMBED> |
|
|
794 | |
|
|
795 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
|
|
796 | |
|
|
797 | =item C<EV_FORK> |
|
|
798 | |
|
|
799 | The event loop has been resumed in the child process after fork (see |
|
|
800 | C<ev_fork>). |
|
|
801 | |
|
|
802 | =item C<EV_ASYNC> |
|
|
803 | |
|
|
804 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
805 | |
566 | =item C<EV_ERROR> |
806 | =item C<EV_ERROR> |
567 | |
807 | |
568 | An unspecified error has occured, the watcher has been stopped. This might |
808 | An unspecified error has occured, the watcher has been stopped. This might |
569 | happen because the watcher could not be properly started because libev |
809 | happen because the watcher could not be properly started because libev |
570 | ran out of memory, a file descriptor was found to be closed or any other |
810 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
641 | =item bool ev_is_pending (ev_TYPE *watcher) |
881 | =item bool ev_is_pending (ev_TYPE *watcher) |
642 | |
882 | |
643 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
883 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
644 | events but its callback has not yet been invoked). As long as a watcher |
884 | events but its callback has not yet been invoked). As long as a watcher |
645 | is pending (but not active) you must not call an init function on it (but |
885 | is pending (but not active) you must not call an init function on it (but |
646 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
886 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
647 | libev (e.g. you cnanot C<free ()> it). |
887 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
888 | it). |
648 | |
889 | |
649 | =item callback = ev_cb (ev_TYPE *watcher) |
890 | =item callback ev_cb (ev_TYPE *watcher) |
650 | |
891 | |
651 | Returns the callback currently set on the watcher. |
892 | Returns the callback currently set on the watcher. |
652 | |
893 | |
653 | =item ev_cb_set (ev_TYPE *watcher, callback) |
894 | =item ev_cb_set (ev_TYPE *watcher, callback) |
654 | |
895 | |
655 | Change the callback. You can change the callback at virtually any time |
896 | Change the callback. You can change the callback at virtually any time |
656 | (modulo threads). |
897 | (modulo threads). |
|
|
898 | |
|
|
899 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
900 | |
|
|
901 | =item int ev_priority (ev_TYPE *watcher) |
|
|
902 | |
|
|
903 | Set and query the priority of the watcher. The priority is a small |
|
|
904 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
905 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
906 | before watchers with lower priority, but priority will not keep watchers |
|
|
907 | from being executed (except for C<ev_idle> watchers). |
|
|
908 | |
|
|
909 | This means that priorities are I<only> used for ordering callback |
|
|
910 | invocation after new events have been received. This is useful, for |
|
|
911 | example, to reduce latency after idling, or more often, to bind two |
|
|
912 | watchers on the same event and make sure one is called first. |
|
|
913 | |
|
|
914 | If you need to suppress invocation when higher priority events are pending |
|
|
915 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
916 | |
|
|
917 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
918 | pending. |
|
|
919 | |
|
|
920 | The default priority used by watchers when no priority has been set is |
|
|
921 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
922 | |
|
|
923 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
924 | fine, as long as you do not mind that the priority value you query might |
|
|
925 | or might not have been adjusted to be within valid range. |
|
|
926 | |
|
|
927 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
928 | |
|
|
929 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
930 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
931 | can deal with that fact. |
|
|
932 | |
|
|
933 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
934 | |
|
|
935 | If the watcher is pending, this function returns clears its pending status |
|
|
936 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
937 | watcher isn't pending it does nothing and returns C<0>. |
657 | |
938 | |
658 | =back |
939 | =back |
659 | |
940 | |
660 | |
941 | |
661 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
942 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
682 | { |
963 | { |
683 | struct my_io *w = (struct my_io *)w_; |
964 | struct my_io *w = (struct my_io *)w_; |
684 | ... |
965 | ... |
685 | } |
966 | } |
686 | |
967 | |
687 | More interesting and less C-conformant ways of catsing your callback type |
968 | More interesting and less C-conformant ways of casting your callback type |
688 | have been omitted.... |
969 | instead have been omitted. |
|
|
970 | |
|
|
971 | Another common scenario is having some data structure with multiple |
|
|
972 | watchers: |
|
|
973 | |
|
|
974 | struct my_biggy |
|
|
975 | { |
|
|
976 | int some_data; |
|
|
977 | ev_timer t1; |
|
|
978 | ev_timer t2; |
|
|
979 | } |
|
|
980 | |
|
|
981 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
982 | you need to use C<offsetof>: |
|
|
983 | |
|
|
984 | #include <stddef.h> |
|
|
985 | |
|
|
986 | static void |
|
|
987 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
988 | { |
|
|
989 | struct my_biggy big = (struct my_biggy * |
|
|
990 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
991 | } |
|
|
992 | |
|
|
993 | static void |
|
|
994 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
995 | { |
|
|
996 | struct my_biggy big = (struct my_biggy * |
|
|
997 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
998 | } |
689 | |
999 | |
690 | |
1000 | |
691 | =head1 WATCHER TYPES |
1001 | =head1 WATCHER TYPES |
692 | |
1002 | |
693 | This section describes each watcher in detail, but will not repeat |
1003 | This section describes each watcher in detail, but will not repeat |
694 | information given in the last section. |
1004 | information given in the last section. Any initialisation/set macros, |
|
|
1005 | functions and members specific to the watcher type are explained. |
|
|
1006 | |
|
|
1007 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
1008 | while the watcher is active, you can look at the member and expect some |
|
|
1009 | sensible content, but you must not modify it (you can modify it while the |
|
|
1010 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
1011 | means you can expect it to have some sensible content while the watcher |
|
|
1012 | is active, but you can also modify it. Modifying it may not do something |
|
|
1013 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
1014 | not crash or malfunction in any way. |
695 | |
1015 | |
696 | |
1016 | |
697 | =head2 C<ev_io> - is this file descriptor readable or writable? |
1017 | =head2 C<ev_io> - is this file descriptor readable or writable? |
698 | |
1018 | |
699 | I/O watchers check whether a file descriptor is readable or writable |
1019 | I/O watchers check whether a file descriptor is readable or writable |
… | |
… | |
706 | |
1026 | |
707 | In general you can register as many read and/or write event watchers per |
1027 | In general you can register as many read and/or write event watchers per |
708 | fd as you want (as long as you don't confuse yourself). Setting all file |
1028 | fd as you want (as long as you don't confuse yourself). Setting all file |
709 | descriptors to non-blocking mode is also usually a good idea (but not |
1029 | descriptors to non-blocking mode is also usually a good idea (but not |
710 | required if you know what you are doing). |
1030 | required if you know what you are doing). |
711 | |
|
|
712 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
713 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
714 | descriptors correctly if you register interest in two or more fds pointing |
|
|
715 | to the same underlying file/socket/etc. description (that is, they share |
|
|
716 | the same underlying "file open"). |
|
|
717 | |
1031 | |
718 | If you must do this, then force the use of a known-to-be-good backend |
1032 | If you must do this, then force the use of a known-to-be-good backend |
719 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1033 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
720 | C<EVBACKEND_POLL>). |
1034 | C<EVBACKEND_POLL>). |
721 | |
1035 | |
… | |
… | |
728 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1042 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
729 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1043 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
730 | |
1044 | |
731 | If you cannot run the fd in non-blocking mode (for example you should not |
1045 | If you cannot run the fd in non-blocking mode (for example you should not |
732 | play around with an Xlib connection), then you have to seperately re-test |
1046 | play around with an Xlib connection), then you have to seperately re-test |
733 | wether a file descriptor is really ready with a known-to-be good interface |
1047 | whether a file descriptor is really ready with a known-to-be good interface |
734 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1048 | such as poll (fortunately in our Xlib example, Xlib already does this on |
735 | its own, so its quite safe to use). |
1049 | its own, so its quite safe to use). |
|
|
1050 | |
|
|
1051 | =head3 The special problem of disappearing file descriptors |
|
|
1052 | |
|
|
1053 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1054 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1055 | such as C<dup>). The reason is that you register interest in some file |
|
|
1056 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1057 | this interest. If another file descriptor with the same number then is |
|
|
1058 | registered with libev, there is no efficient way to see that this is, in |
|
|
1059 | fact, a different file descriptor. |
|
|
1060 | |
|
|
1061 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1062 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1063 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1064 | it is assumed that the file descriptor stays the same. That means that |
|
|
1065 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1066 | descriptor even if the file descriptor number itself did not change. |
|
|
1067 | |
|
|
1068 | This is how one would do it normally anyway, the important point is that |
|
|
1069 | the libev application should not optimise around libev but should leave |
|
|
1070 | optimisations to libev. |
|
|
1071 | |
|
|
1072 | =head3 The special problem of dup'ed file descriptors |
|
|
1073 | |
|
|
1074 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1075 | but only events for the underlying file descriptions. That means when you |
|
|
1076 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1077 | events for them, only one file descriptor might actually receive events. |
|
|
1078 | |
|
|
1079 | There is no workaround possible except not registering events |
|
|
1080 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1081 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1082 | |
|
|
1083 | =head3 The special problem of fork |
|
|
1084 | |
|
|
1085 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1086 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1087 | it in the child. |
|
|
1088 | |
|
|
1089 | To support fork in your programs, you either have to call |
|
|
1090 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1091 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1092 | C<EVBACKEND_POLL>. |
|
|
1093 | |
|
|
1094 | =head3 The special problem of SIGPIPE |
|
|
1095 | |
|
|
1096 | While not really specific to libev, it is easy to forget about SIGPIPE: |
|
|
1097 | when reading from a pipe whose other end has been closed, your program |
|
|
1098 | gets send a SIGPIPE, which, by default, aborts your program. For most |
|
|
1099 | programs this is sensible behaviour, for daemons, this is usually |
|
|
1100 | undesirable. |
|
|
1101 | |
|
|
1102 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1103 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
|
|
1104 | somewhere, as that would have given you a big clue). |
|
|
1105 | |
|
|
1106 | |
|
|
1107 | =head3 Watcher-Specific Functions |
736 | |
1108 | |
737 | =over 4 |
1109 | =over 4 |
738 | |
1110 | |
739 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1111 | =item ev_io_init (ev_io *, callback, int fd, int events) |
740 | |
1112 | |
… | |
… | |
742 | |
1114 | |
743 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1115 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
744 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
1116 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
745 | C<EV_READ | EV_WRITE> to receive the given events. |
1117 | C<EV_READ | EV_WRITE> to receive the given events. |
746 | |
1118 | |
|
|
1119 | =item int fd [read-only] |
|
|
1120 | |
|
|
1121 | The file descriptor being watched. |
|
|
1122 | |
|
|
1123 | =item int events [read-only] |
|
|
1124 | |
|
|
1125 | The events being watched. |
|
|
1126 | |
747 | =back |
1127 | =back |
748 | |
1128 | |
|
|
1129 | =head3 Examples |
|
|
1130 | |
749 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1131 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
750 | readable, but only once. Since it is likely line-buffered, you could |
1132 | readable, but only once. Since it is likely line-buffered, you could |
751 | attempt to read a whole line in the callback: |
1133 | attempt to read a whole line in the callback. |
752 | |
1134 | |
753 | static void |
1135 | static void |
754 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1136 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
755 | { |
1137 | { |
756 | ev_io_stop (loop, w); |
1138 | ev_io_stop (loop, w); |
… | |
… | |
786 | |
1168 | |
787 | The callback is guarenteed to be invoked only when its timeout has passed, |
1169 | The callback is guarenteed to be invoked only when its timeout has passed, |
788 | but if multiple timers become ready during the same loop iteration then |
1170 | but if multiple timers become ready during the same loop iteration then |
789 | order of execution is undefined. |
1171 | order of execution is undefined. |
790 | |
1172 | |
|
|
1173 | =head3 Watcher-Specific Functions and Data Members |
|
|
1174 | |
791 | =over 4 |
1175 | =over 4 |
792 | |
1176 | |
793 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1177 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
794 | |
1178 | |
795 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1179 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
803 | configure a timer to trigger every 10 seconds, then it will trigger at |
1187 | configure a timer to trigger every 10 seconds, then it will trigger at |
804 | exactly 10 second intervals. If, however, your program cannot keep up with |
1188 | exactly 10 second intervals. If, however, your program cannot keep up with |
805 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1189 | the timer (because it takes longer than those 10 seconds to do stuff) the |
806 | timer will not fire more than once per event loop iteration. |
1190 | timer will not fire more than once per event loop iteration. |
807 | |
1191 | |
808 | =item ev_timer_again (loop) |
1192 | =item ev_timer_again (loop, ev_timer *) |
809 | |
1193 | |
810 | This will act as if the timer timed out and restart it again if it is |
1194 | This will act as if the timer timed out and restart it again if it is |
811 | repeating. The exact semantics are: |
1195 | repeating. The exact semantics are: |
812 | |
1196 | |
|
|
1197 | If the timer is pending, its pending status is cleared. |
|
|
1198 | |
813 | If the timer is started but nonrepeating, stop it. |
1199 | If the timer is started but nonrepeating, stop it (as if it timed out). |
814 | |
1200 | |
815 | If the timer is repeating, either start it if necessary (with the repeat |
1201 | If the timer is repeating, either start it if necessary (with the |
816 | value), or reset the running timer to the repeat value. |
1202 | C<repeat> value), or reset the running timer to the C<repeat> value. |
817 | |
1203 | |
818 | This sounds a bit complicated, but here is a useful and typical |
1204 | This sounds a bit complicated, but here is a useful and typical |
819 | example: Imagine you have a tcp connection and you want a so-called idle |
1205 | example: Imagine you have a tcp connection and you want a so-called idle |
820 | timeout, that is, you want to be called when there have been, say, 60 |
1206 | timeout, that is, you want to be called when there have been, say, 60 |
821 | seconds of inactivity on the socket. The easiest way to do this is to |
1207 | seconds of inactivity on the socket. The easiest way to do this is to |
822 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
1208 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
823 | time you successfully read or write some data. If you go into an idle |
1209 | C<ev_timer_again> each time you successfully read or write some data. If |
824 | state where you do not expect data to travel on the socket, you can stop |
1210 | you go into an idle state where you do not expect data to travel on the |
825 | the timer, and again will automatically restart it if need be. |
1211 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
1212 | automatically restart it if need be. |
|
|
1213 | |
|
|
1214 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1215 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1216 | |
|
|
1217 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1218 | ev_timer_again (loop, timer); |
|
|
1219 | ... |
|
|
1220 | timer->again = 17.; |
|
|
1221 | ev_timer_again (loop, timer); |
|
|
1222 | ... |
|
|
1223 | timer->again = 10.; |
|
|
1224 | ev_timer_again (loop, timer); |
|
|
1225 | |
|
|
1226 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1227 | you want to modify its timeout value. |
|
|
1228 | |
|
|
1229 | =item ev_tstamp repeat [read-write] |
|
|
1230 | |
|
|
1231 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
1232 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
1233 | which is also when any modifications are taken into account. |
826 | |
1234 | |
827 | =back |
1235 | =back |
828 | |
1236 | |
|
|
1237 | =head3 Examples |
|
|
1238 | |
829 | Example: create a timer that fires after 60 seconds. |
1239 | Example: Create a timer that fires after 60 seconds. |
830 | |
1240 | |
831 | static void |
1241 | static void |
832 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1242 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
833 | { |
1243 | { |
834 | .. one minute over, w is actually stopped right here |
1244 | .. one minute over, w is actually stopped right here |
… | |
… | |
836 | |
1246 | |
837 | struct ev_timer mytimer; |
1247 | struct ev_timer mytimer; |
838 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1248 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
839 | ev_timer_start (loop, &mytimer); |
1249 | ev_timer_start (loop, &mytimer); |
840 | |
1250 | |
841 | Example: create a timeout timer that times out after 10 seconds of |
1251 | Example: Create a timeout timer that times out after 10 seconds of |
842 | inactivity. |
1252 | inactivity. |
843 | |
1253 | |
844 | static void |
1254 | static void |
845 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1255 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
846 | { |
1256 | { |
… | |
… | |
866 | but on wallclock time (absolute time). You can tell a periodic watcher |
1276 | but on wallclock time (absolute time). You can tell a periodic watcher |
867 | to trigger "at" some specific point in time. For example, if you tell a |
1277 | to trigger "at" some specific point in time. For example, if you tell a |
868 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1278 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
869 | + 10.>) and then reset your system clock to the last year, then it will |
1279 | + 10.>) and then reset your system clock to the last year, then it will |
870 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1280 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
871 | roughly 10 seconds later and of course not if you reset your system time |
1281 | roughly 10 seconds later). |
872 | again). |
|
|
873 | |
1282 | |
874 | They can also be used to implement vastly more complex timers, such as |
1283 | They can also be used to implement vastly more complex timers, such as |
875 | triggering an event on eahc midnight, local time. |
1284 | triggering an event on each midnight, local time or other, complicated, |
|
|
1285 | rules. |
876 | |
1286 | |
877 | As with timers, the callback is guarenteed to be invoked only when the |
1287 | As with timers, the callback is guarenteed to be invoked only when the |
878 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1288 | time (C<at>) has been passed, but if multiple periodic timers become ready |
879 | during the same loop iteration then order of execution is undefined. |
1289 | during the same loop iteration then order of execution is undefined. |
880 | |
1290 | |
|
|
1291 | =head3 Watcher-Specific Functions and Data Members |
|
|
1292 | |
881 | =over 4 |
1293 | =over 4 |
882 | |
1294 | |
883 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1295 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
884 | |
1296 | |
885 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1297 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
887 | Lots of arguments, lets sort it out... There are basically three modes of |
1299 | Lots of arguments, lets sort it out... There are basically three modes of |
888 | operation, and we will explain them from simplest to complex: |
1300 | operation, and we will explain them from simplest to complex: |
889 | |
1301 | |
890 | =over 4 |
1302 | =over 4 |
891 | |
1303 | |
892 | =item * absolute timer (interval = reschedule_cb = 0) |
1304 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
893 | |
1305 | |
894 | In this configuration the watcher triggers an event at the wallclock time |
1306 | In this configuration the watcher triggers an event at the wallclock time |
895 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1307 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
896 | that is, if it is to be run at January 1st 2011 then it will run when the |
1308 | that is, if it is to be run at January 1st 2011 then it will run when the |
897 | system time reaches or surpasses this time. |
1309 | system time reaches or surpasses this time. |
898 | |
1310 | |
899 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1311 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
900 | |
1312 | |
901 | In this mode the watcher will always be scheduled to time out at the next |
1313 | In this mode the watcher will always be scheduled to time out at the next |
902 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1314 | C<at + N * interval> time (for some integer N, which can also be negative) |
903 | of any time jumps. |
1315 | and then repeat, regardless of any time jumps. |
904 | |
1316 | |
905 | This can be used to create timers that do not drift with respect to system |
1317 | This can be used to create timers that do not drift with respect to system |
906 | time: |
1318 | time: |
907 | |
1319 | |
908 | ev_periodic_set (&periodic, 0., 3600., 0); |
1320 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
914 | |
1326 | |
915 | Another way to think about it (for the mathematically inclined) is that |
1327 | Another way to think about it (for the mathematically inclined) is that |
916 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1328 | C<ev_periodic> will try to run the callback in this mode at the next possible |
917 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1329 | time where C<time = at (mod interval)>, regardless of any time jumps. |
918 | |
1330 | |
|
|
1331 | For numerical stability it is preferable that the C<at> value is near |
|
|
1332 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1333 | this value. |
|
|
1334 | |
919 | =item * manual reschedule mode (reschedule_cb = callback) |
1335 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
920 | |
1336 | |
921 | In this mode the values for C<interval> and C<at> are both being |
1337 | In this mode the values for C<interval> and C<at> are both being |
922 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1338 | ignored. Instead, each time the periodic watcher gets scheduled, the |
923 | reschedule callback will be called with the watcher as first, and the |
1339 | reschedule callback will be called with the watcher as first, and the |
924 | current time as second argument. |
1340 | current time as second argument. |
925 | |
1341 | |
926 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1342 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
927 | ever, or make any event loop modifications>. If you need to stop it, |
1343 | ever, or make any event loop modifications>. If you need to stop it, |
928 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1344 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
929 | starting a prepare watcher). |
1345 | starting an C<ev_prepare> watcher, which is legal). |
930 | |
1346 | |
931 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1347 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
932 | ev_tstamp now)>, e.g.: |
1348 | ev_tstamp now)>, e.g.: |
933 | |
1349 | |
934 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1350 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
957 | Simply stops and restarts the periodic watcher again. This is only useful |
1373 | Simply stops and restarts the periodic watcher again. This is only useful |
958 | when you changed some parameters or the reschedule callback would return |
1374 | when you changed some parameters or the reschedule callback would return |
959 | a different time than the last time it was called (e.g. in a crond like |
1375 | a different time than the last time it was called (e.g. in a crond like |
960 | program when the crontabs have changed). |
1376 | program when the crontabs have changed). |
961 | |
1377 | |
|
|
1378 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
|
|
1379 | |
|
|
1380 | When active, returns the absolute time that the watcher is supposed to |
|
|
1381 | trigger next. |
|
|
1382 | |
|
|
1383 | =item ev_tstamp offset [read-write] |
|
|
1384 | |
|
|
1385 | When repeating, this contains the offset value, otherwise this is the |
|
|
1386 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1387 | |
|
|
1388 | Can be modified any time, but changes only take effect when the periodic |
|
|
1389 | timer fires or C<ev_periodic_again> is being called. |
|
|
1390 | |
|
|
1391 | =item ev_tstamp interval [read-write] |
|
|
1392 | |
|
|
1393 | The current interval value. Can be modified any time, but changes only |
|
|
1394 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1395 | called. |
|
|
1396 | |
|
|
1397 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1398 | |
|
|
1399 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1400 | switched off. Can be changed any time, but changes only take effect when |
|
|
1401 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1402 | |
962 | =back |
1403 | =back |
963 | |
1404 | |
|
|
1405 | =head3 Examples |
|
|
1406 | |
964 | Example: call a callback every hour, or, more precisely, whenever the |
1407 | Example: Call a callback every hour, or, more precisely, whenever the |
965 | system clock is divisible by 3600. The callback invocation times have |
1408 | system clock is divisible by 3600. The callback invocation times have |
966 | potentially a lot of jittering, but good long-term stability. |
1409 | potentially a lot of jittering, but good long-term stability. |
967 | |
1410 | |
968 | static void |
1411 | static void |
969 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1412 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
973 | |
1416 | |
974 | struct ev_periodic hourly_tick; |
1417 | struct ev_periodic hourly_tick; |
975 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1418 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
976 | ev_periodic_start (loop, &hourly_tick); |
1419 | ev_periodic_start (loop, &hourly_tick); |
977 | |
1420 | |
978 | Example: the same as above, but use a reschedule callback to do it: |
1421 | Example: The same as above, but use a reschedule callback to do it: |
979 | |
1422 | |
980 | #include <math.h> |
1423 | #include <math.h> |
981 | |
1424 | |
982 | static ev_tstamp |
1425 | static ev_tstamp |
983 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1426 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
985 | return fmod (now, 3600.) + 3600.; |
1428 | return fmod (now, 3600.) + 3600.; |
986 | } |
1429 | } |
987 | |
1430 | |
988 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1431 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
989 | |
1432 | |
990 | Example: call a callback every hour, starting now: |
1433 | Example: Call a callback every hour, starting now: |
991 | |
1434 | |
992 | struct ev_periodic hourly_tick; |
1435 | struct ev_periodic hourly_tick; |
993 | ev_periodic_init (&hourly_tick, clock_cb, |
1436 | ev_periodic_init (&hourly_tick, clock_cb, |
994 | fmod (ev_now (loop), 3600.), 3600., 0); |
1437 | fmod (ev_now (loop), 3600.), 3600., 0); |
995 | ev_periodic_start (loop, &hourly_tick); |
1438 | ev_periodic_start (loop, &hourly_tick); |
… | |
… | |
1007 | with the kernel (thus it coexists with your own signal handlers as long |
1450 | with the kernel (thus it coexists with your own signal handlers as long |
1008 | as you don't register any with libev). Similarly, when the last signal |
1451 | as you don't register any with libev). Similarly, when the last signal |
1009 | watcher for a signal is stopped libev will reset the signal handler to |
1452 | watcher for a signal is stopped libev will reset the signal handler to |
1010 | SIG_DFL (regardless of what it was set to before). |
1453 | SIG_DFL (regardless of what it was set to before). |
1011 | |
1454 | |
|
|
1455 | If possible and supported, libev will install its handlers with |
|
|
1456 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
|
|
1457 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1458 | signals you can block all signals in an C<ev_check> watcher and unblock |
|
|
1459 | them in an C<ev_prepare> watcher. |
|
|
1460 | |
|
|
1461 | =head3 Watcher-Specific Functions and Data Members |
|
|
1462 | |
1012 | =over 4 |
1463 | =over 4 |
1013 | |
1464 | |
1014 | =item ev_signal_init (ev_signal *, callback, int signum) |
1465 | =item ev_signal_init (ev_signal *, callback, int signum) |
1015 | |
1466 | |
1016 | =item ev_signal_set (ev_signal *, int signum) |
1467 | =item ev_signal_set (ev_signal *, int signum) |
1017 | |
1468 | |
1018 | Configures the watcher to trigger on the given signal number (usually one |
1469 | Configures the watcher to trigger on the given signal number (usually one |
1019 | of the C<SIGxxx> constants). |
1470 | of the C<SIGxxx> constants). |
1020 | |
1471 | |
|
|
1472 | =item int signum [read-only] |
|
|
1473 | |
|
|
1474 | The signal the watcher watches out for. |
|
|
1475 | |
1021 | =back |
1476 | =back |
1022 | |
1477 | |
|
|
1478 | =head3 Examples |
|
|
1479 | |
|
|
1480 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1481 | |
|
|
1482 | static void |
|
|
1483 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1484 | { |
|
|
1485 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1486 | } |
|
|
1487 | |
|
|
1488 | struct ev_signal signal_watcher; |
|
|
1489 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1490 | ev_signal_start (loop, &sigint_cb); |
|
|
1491 | |
1023 | |
1492 | |
1024 | =head2 C<ev_child> - watch out for process status changes |
1493 | =head2 C<ev_child> - watch out for process status changes |
1025 | |
1494 | |
1026 | Child watchers trigger when your process receives a SIGCHLD in response to |
1495 | Child watchers trigger when your process receives a SIGCHLD in response to |
1027 | some child status changes (most typically when a child of yours dies). |
1496 | some child status changes (most typically when a child of yours dies). It |
|
|
1497 | is permissible to install a child watcher I<after> the child has been |
|
|
1498 | forked (which implies it might have already exited), as long as the event |
|
|
1499 | loop isn't entered (or is continued from a watcher). |
|
|
1500 | |
|
|
1501 | Only the default event loop is capable of handling signals, and therefore |
|
|
1502 | you can only rgeister child watchers in the default event loop. |
|
|
1503 | |
|
|
1504 | =head3 Process Interaction |
|
|
1505 | |
|
|
1506 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
|
|
1507 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1508 | the first child watcher is started after the child exits. The occurance |
|
|
1509 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
|
|
1510 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1511 | children, even ones not watched. |
|
|
1512 | |
|
|
1513 | =head3 Overriding the Built-In Processing |
|
|
1514 | |
|
|
1515 | Libev offers no special support for overriding the built-in child |
|
|
1516 | processing, but if your application collides with libev's default child |
|
|
1517 | handler, you can override it easily by installing your own handler for |
|
|
1518 | C<SIGCHLD> after initialising the default loop, and making sure the |
|
|
1519 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1520 | event-based approach to child reaping and thus use libev's support for |
|
|
1521 | that, so other libev users can use C<ev_child> watchers freely. |
|
|
1522 | |
|
|
1523 | =head3 Watcher-Specific Functions and Data Members |
1028 | |
1524 | |
1029 | =over 4 |
1525 | =over 4 |
1030 | |
1526 | |
1031 | =item ev_child_init (ev_child *, callback, int pid) |
1527 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1032 | |
1528 | |
1033 | =item ev_child_set (ev_child *, int pid) |
1529 | =item ev_child_set (ev_child *, int pid, int trace) |
1034 | |
1530 | |
1035 | Configures the watcher to wait for status changes of process C<pid> (or |
1531 | Configures the watcher to wait for status changes of process C<pid> (or |
1036 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1532 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1037 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1533 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1038 | the status word (use the macros from C<sys/wait.h> and see your systems |
1534 | the status word (use the macros from C<sys/wait.h> and see your systems |
1039 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1535 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1040 | process causing the status change. |
1536 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1537 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1538 | activate the watcher when the process is stopped or continued). |
|
|
1539 | |
|
|
1540 | =item int pid [read-only] |
|
|
1541 | |
|
|
1542 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1543 | |
|
|
1544 | =item int rpid [read-write] |
|
|
1545 | |
|
|
1546 | The process id that detected a status change. |
|
|
1547 | |
|
|
1548 | =item int rstatus [read-write] |
|
|
1549 | |
|
|
1550 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1551 | C<waitpid> and C<sys/wait.h> documentation for details). |
1041 | |
1552 | |
1042 | =back |
1553 | =back |
1043 | |
1554 | |
1044 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1555 | =head3 Examples |
|
|
1556 | |
|
|
1557 | Example: C<fork()> a new process and install a child handler to wait for |
|
|
1558 | its completion. |
|
|
1559 | |
|
|
1560 | ev_child cw; |
1045 | |
1561 | |
1046 | static void |
1562 | static void |
1047 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1563 | child_cb (EV_P_ struct ev_child *w, int revents) |
1048 | { |
1564 | { |
1049 | ev_unloop (loop, EVUNLOOP_ALL); |
1565 | ev_child_stop (EV_A_ w); |
|
|
1566 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1050 | } |
1567 | } |
1051 | |
1568 | |
1052 | struct ev_signal signal_watcher; |
1569 | pid_t pid = fork (); |
1053 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1570 | |
1054 | ev_signal_start (loop, &sigint_cb); |
1571 | if (pid < 0) |
|
|
1572 | // error |
|
|
1573 | else if (pid == 0) |
|
|
1574 | { |
|
|
1575 | // the forked child executes here |
|
|
1576 | exit (1); |
|
|
1577 | } |
|
|
1578 | else |
|
|
1579 | { |
|
|
1580 | ev_child_init (&cw, child_cb, pid, 0); |
|
|
1581 | ev_child_start (EV_DEFAULT_ &cw); |
|
|
1582 | } |
|
|
1583 | |
|
|
1584 | |
|
|
1585 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1586 | |
|
|
1587 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1588 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1589 | compared to the last time, invoking the callback if it did. |
|
|
1590 | |
|
|
1591 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1592 | not exist" is a status change like any other. The condition "path does |
|
|
1593 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1594 | otherwise always forced to be at least one) and all the other fields of |
|
|
1595 | the stat buffer having unspecified contents. |
|
|
1596 | |
|
|
1597 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1598 | relative and your working directory changes, the behaviour is undefined. |
|
|
1599 | |
|
|
1600 | Since there is no standard to do this, the portable implementation simply |
|
|
1601 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
|
|
1602 | can specify a recommended polling interval for this case. If you specify |
|
|
1603 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1604 | unspecified default> value will be used (which you can expect to be around |
|
|
1605 | five seconds, although this might change dynamically). Libev will also |
|
|
1606 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1607 | usually overkill. |
|
|
1608 | |
|
|
1609 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1610 | as even with OS-supported change notifications, this can be |
|
|
1611 | resource-intensive. |
|
|
1612 | |
|
|
1613 | At the time of this writing, only the Linux inotify interface is |
|
|
1614 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1615 | reader, note, however, that the author sees no way of implementing ev_stat |
|
|
1616 | semantics with kqueue). Inotify will be used to give hints only and should |
|
|
1617 | not change the semantics of C<ev_stat> watchers, which means that libev |
|
|
1618 | sometimes needs to fall back to regular polling again even with inotify, |
|
|
1619 | but changes are usually detected immediately, and if the file exists there |
|
|
1620 | will be no polling. |
|
|
1621 | |
|
|
1622 | =head3 ABI Issues (Largefile Support) |
|
|
1623 | |
|
|
1624 | Libev by default (unless the user overrides this) uses the default |
|
|
1625 | compilation environment, which means that on systems with optionally |
|
|
1626 | disabled large file support, you get the 32 bit version of the stat |
|
|
1627 | structure. When using the library from programs that change the ABI to |
|
|
1628 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1629 | compile libev with the same flags to get binary compatibility. This is |
|
|
1630 | obviously the case with any flags that change the ABI, but the problem is |
|
|
1631 | most noticably with ev_stat and largefile support. |
|
|
1632 | |
|
|
1633 | =head3 Inotify |
|
|
1634 | |
|
|
1635 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1636 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1637 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1638 | when the first C<ev_stat> watcher is being started. |
|
|
1639 | |
|
|
1640 | Inotify presence does not change the semantics of C<ev_stat> watchers |
|
|
1641 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1642 | making regular C<stat> calls. Even in the presence of inotify support |
|
|
1643 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1644 | |
|
|
1645 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1646 | implement this functionality, due to the requirement of having a file |
|
|
1647 | descriptor open on the object at all times). |
|
|
1648 | |
|
|
1649 | =head3 The special problem of stat time resolution |
|
|
1650 | |
|
|
1651 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1652 | even on systems where the resolution is higher, many filesystems still |
|
|
1653 | only support whole seconds. |
|
|
1654 | |
|
|
1655 | That means that, if the time is the only thing that changes, you can |
|
|
1656 | easily miss updates: on the first update, C<ev_stat> detects a change and |
|
|
1657 | calls your callback, which does something. When there is another update |
|
|
1658 | within the same second, C<ev_stat> will be unable to detect it as the stat |
|
|
1659 | data does not change. |
|
|
1660 | |
|
|
1661 | The solution to this is to delay acting on a change for slightly more |
|
|
1662 | than second (or till slightly after the next full second boundary), using |
|
|
1663 | a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02); |
|
|
1664 | ev_timer_again (loop, w)>). |
|
|
1665 | |
|
|
1666 | The C<.02> offset is added to work around small timing inconsistencies |
|
|
1667 | of some operating systems (where the second counter of the current time |
|
|
1668 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
1669 | C<gettimeofday> might return a timestamp with a full second later than |
|
|
1670 | a subsequent C<time> call - if the equivalent of C<time ()> is used to |
|
|
1671 | update file times then there will be a small window where the kernel uses |
|
|
1672 | the previous second to update file times but libev might already execute |
|
|
1673 | the timer callback). |
|
|
1674 | |
|
|
1675 | =head3 Watcher-Specific Functions and Data Members |
|
|
1676 | |
|
|
1677 | =over 4 |
|
|
1678 | |
|
|
1679 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1680 | |
|
|
1681 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1682 | |
|
|
1683 | Configures the watcher to wait for status changes of the given |
|
|
1684 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1685 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1686 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1687 | path for as long as the watcher is active. |
|
|
1688 | |
|
|
1689 | The callback will receive C<EV_STAT> when a change was detected, relative |
|
|
1690 | to the attributes at the time the watcher was started (or the last change |
|
|
1691 | was detected). |
|
|
1692 | |
|
|
1693 | =item ev_stat_stat (loop, ev_stat *) |
|
|
1694 | |
|
|
1695 | Updates the stat buffer immediately with new values. If you change the |
|
|
1696 | watched path in your callback, you could call this function to avoid |
|
|
1697 | detecting this change (while introducing a race condition if you are not |
|
|
1698 | the only one changing the path). Can also be useful simply to find out the |
|
|
1699 | new values. |
|
|
1700 | |
|
|
1701 | =item ev_statdata attr [read-only] |
|
|
1702 | |
|
|
1703 | The most-recently detected attributes of the file. Although the type is |
|
|
1704 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1705 | suitable for your system, but you can only rely on the POSIX-standardised |
|
|
1706 | members to be present. If the C<st_nlink> member is C<0>, then there was |
|
|
1707 | some error while C<stat>ing the file. |
|
|
1708 | |
|
|
1709 | =item ev_statdata prev [read-only] |
|
|
1710 | |
|
|
1711 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1712 | C<prev> != C<attr>, or, more precisely, one or more of these members |
|
|
1713 | differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>, |
|
|
1714 | C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>. |
|
|
1715 | |
|
|
1716 | =item ev_tstamp interval [read-only] |
|
|
1717 | |
|
|
1718 | The specified interval. |
|
|
1719 | |
|
|
1720 | =item const char *path [read-only] |
|
|
1721 | |
|
|
1722 | The filesystem path that is being watched. |
|
|
1723 | |
|
|
1724 | =back |
|
|
1725 | |
|
|
1726 | =head3 Examples |
|
|
1727 | |
|
|
1728 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1729 | |
|
|
1730 | static void |
|
|
1731 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1732 | { |
|
|
1733 | /* /etc/passwd changed in some way */ |
|
|
1734 | if (w->attr.st_nlink) |
|
|
1735 | { |
|
|
1736 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1737 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1738 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1739 | } |
|
|
1740 | else |
|
|
1741 | /* you shalt not abuse printf for puts */ |
|
|
1742 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1743 | "if this is windows, they already arrived\n"); |
|
|
1744 | } |
|
|
1745 | |
|
|
1746 | ... |
|
|
1747 | ev_stat passwd; |
|
|
1748 | |
|
|
1749 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
1750 | ev_stat_start (loop, &passwd); |
|
|
1751 | |
|
|
1752 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1753 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1754 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1755 | C<ev_timer> callback invocation). |
|
|
1756 | |
|
|
1757 | static ev_stat passwd; |
|
|
1758 | static ev_timer timer; |
|
|
1759 | |
|
|
1760 | static void |
|
|
1761 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1762 | { |
|
|
1763 | ev_timer_stop (EV_A_ w); |
|
|
1764 | |
|
|
1765 | /* now it's one second after the most recent passwd change */ |
|
|
1766 | } |
|
|
1767 | |
|
|
1768 | static void |
|
|
1769 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1770 | { |
|
|
1771 | /* reset the one-second timer */ |
|
|
1772 | ev_timer_again (EV_A_ &timer); |
|
|
1773 | } |
|
|
1774 | |
|
|
1775 | ... |
|
|
1776 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1777 | ev_stat_start (loop, &passwd); |
|
|
1778 | ev_timer_init (&timer, timer_cb, 0., 1.02); |
1055 | |
1779 | |
1056 | |
1780 | |
1057 | =head2 C<ev_idle> - when you've got nothing better to do... |
1781 | =head2 C<ev_idle> - when you've got nothing better to do... |
1058 | |
1782 | |
1059 | Idle watchers trigger events when there are no other events are pending |
1783 | Idle watchers trigger events when no other events of the same or higher |
1060 | (prepare, check and other idle watchers do not count). That is, as long |
1784 | priority are pending (prepare, check and other idle watchers do not |
1061 | as your process is busy handling sockets or timeouts (or even signals, |
1785 | count). |
1062 | imagine) it will not be triggered. But when your process is idle all idle |
1786 | |
1063 | watchers are being called again and again, once per event loop iteration - |
1787 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1788 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1789 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1790 | are pending), the idle watchers are being called once per event loop |
1064 | until stopped, that is, or your process receives more events and becomes |
1791 | iteration - until stopped, that is, or your process receives more events |
1065 | busy. |
1792 | and becomes busy again with higher priority stuff. |
1066 | |
1793 | |
1067 | The most noteworthy effect is that as long as any idle watchers are |
1794 | The most noteworthy effect is that as long as any idle watchers are |
1068 | active, the process will not block when waiting for new events. |
1795 | active, the process will not block when waiting for new events. |
1069 | |
1796 | |
1070 | Apart from keeping your process non-blocking (which is a useful |
1797 | Apart from keeping your process non-blocking (which is a useful |
1071 | effect on its own sometimes), idle watchers are a good place to do |
1798 | effect on its own sometimes), idle watchers are a good place to do |
1072 | "pseudo-background processing", or delay processing stuff to after the |
1799 | "pseudo-background processing", or delay processing stuff to after the |
1073 | event loop has handled all outstanding events. |
1800 | event loop has handled all outstanding events. |
1074 | |
1801 | |
|
|
1802 | =head3 Watcher-Specific Functions and Data Members |
|
|
1803 | |
1075 | =over 4 |
1804 | =over 4 |
1076 | |
1805 | |
1077 | =item ev_idle_init (ev_signal *, callback) |
1806 | =item ev_idle_init (ev_signal *, callback) |
1078 | |
1807 | |
1079 | Initialises and configures the idle watcher - it has no parameters of any |
1808 | Initialises and configures the idle watcher - it has no parameters of any |
1080 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1809 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1081 | believe me. |
1810 | believe me. |
1082 | |
1811 | |
1083 | =back |
1812 | =back |
1084 | |
1813 | |
|
|
1814 | =head3 Examples |
|
|
1815 | |
1085 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
1816 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1086 | callback, free it. Alos, use no error checking, as usual. |
1817 | callback, free it. Also, use no error checking, as usual. |
1087 | |
1818 | |
1088 | static void |
1819 | static void |
1089 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1820 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1090 | { |
1821 | { |
1091 | free (w); |
1822 | free (w); |
1092 | // now do something you wanted to do when the program has |
1823 | // now do something you wanted to do when the program has |
1093 | // no longer asnything immediate to do. |
1824 | // no longer anything immediate to do. |
1094 | } |
1825 | } |
1095 | |
1826 | |
1096 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1827 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1097 | ev_idle_init (idle_watcher, idle_cb); |
1828 | ev_idle_init (idle_watcher, idle_cb); |
1098 | ev_idle_start (loop, idle_cb); |
1829 | ev_idle_start (loop, idle_cb); |
… | |
… | |
1102 | |
1833 | |
1103 | Prepare and check watchers are usually (but not always) used in tandem: |
1834 | Prepare and check watchers are usually (but not always) used in tandem: |
1104 | prepare watchers get invoked before the process blocks and check watchers |
1835 | prepare watchers get invoked before the process blocks and check watchers |
1105 | afterwards. |
1836 | afterwards. |
1106 | |
1837 | |
|
|
1838 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1839 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1840 | watchers. Other loops than the current one are fine, however. The |
|
|
1841 | rationale behind this is that you do not need to check for recursion in |
|
|
1842 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1843 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1844 | called in pairs bracketing the blocking call. |
|
|
1845 | |
1107 | Their main purpose is to integrate other event mechanisms into libev and |
1846 | Their main purpose is to integrate other event mechanisms into libev and |
1108 | their use is somewhat advanced. This could be used, for example, to track |
1847 | their use is somewhat advanced. This could be used, for example, to track |
1109 | variable changes, implement your own watchers, integrate net-snmp or a |
1848 | variable changes, implement your own watchers, integrate net-snmp or a |
1110 | coroutine library and lots more. |
1849 | coroutine library and lots more. They are also occasionally useful if |
|
|
1850 | you cache some data and want to flush it before blocking (for example, |
|
|
1851 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1852 | watcher). |
1111 | |
1853 | |
1112 | This is done by examining in each prepare call which file descriptors need |
1854 | This is done by examining in each prepare call which file descriptors need |
1113 | to be watched by the other library, registering C<ev_io> watchers for |
1855 | to be watched by the other library, registering C<ev_io> watchers for |
1114 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1856 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1115 | provide just this functionality). Then, in the check watcher you check for |
1857 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
1125 | with priority higher than or equal to the event loop and one coroutine |
1867 | with priority higher than or equal to the event loop and one coroutine |
1126 | of lower priority, but only once, using idle watchers to keep the event |
1868 | of lower priority, but only once, using idle watchers to keep the event |
1127 | loop from blocking if lower-priority coroutines are active, thus mapping |
1869 | loop from blocking if lower-priority coroutines are active, thus mapping |
1128 | low-priority coroutines to idle/background tasks). |
1870 | low-priority coroutines to idle/background tasks). |
1129 | |
1871 | |
|
|
1872 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1873 | priority, to ensure that they are being run before any other watchers |
|
|
1874 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1875 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1876 | supports this, they might get executed before other C<ev_check> watchers |
|
|
1877 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1878 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1879 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1880 | coexist peacefully with others). |
|
|
1881 | |
|
|
1882 | =head3 Watcher-Specific Functions and Data Members |
|
|
1883 | |
1130 | =over 4 |
1884 | =over 4 |
1131 | |
1885 | |
1132 | =item ev_prepare_init (ev_prepare *, callback) |
1886 | =item ev_prepare_init (ev_prepare *, callback) |
1133 | |
1887 | |
1134 | =item ev_check_init (ev_check *, callback) |
1888 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1137 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1891 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1138 | macros, but using them is utterly, utterly and completely pointless. |
1892 | macros, but using them is utterly, utterly and completely pointless. |
1139 | |
1893 | |
1140 | =back |
1894 | =back |
1141 | |
1895 | |
1142 | Example: *TODO*. |
1896 | =head3 Examples |
|
|
1897 | |
|
|
1898 | There are a number of principal ways to embed other event loops or modules |
|
|
1899 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1900 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1901 | use as a working example. Another Perl module named C<EV::Glib> embeds a |
|
|
1902 | Glib main context into libev, and finally, C<Glib::EV> embeds EV into the |
|
|
1903 | Glib event loop). |
|
|
1904 | |
|
|
1905 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
|
|
1906 | and in a check watcher, destroy them and call into libadns. What follows |
|
|
1907 | is pseudo-code only of course. This requires you to either use a low |
|
|
1908 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1909 | the callbacks for the IO/timeout watchers might not have been called yet. |
|
|
1910 | |
|
|
1911 | static ev_io iow [nfd]; |
|
|
1912 | static ev_timer tw; |
|
|
1913 | |
|
|
1914 | static void |
|
|
1915 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1916 | { |
|
|
1917 | } |
|
|
1918 | |
|
|
1919 | // create io watchers for each fd and a timer before blocking |
|
|
1920 | static void |
|
|
1921 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1922 | { |
|
|
1923 | int timeout = 3600000; |
|
|
1924 | struct pollfd fds [nfd]; |
|
|
1925 | // actual code will need to loop here and realloc etc. |
|
|
1926 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1927 | |
|
|
1928 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1929 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1930 | ev_timer_start (loop, &tw); |
|
|
1931 | |
|
|
1932 | // create one ev_io per pollfd |
|
|
1933 | for (int i = 0; i < nfd; ++i) |
|
|
1934 | { |
|
|
1935 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1936 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1937 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1938 | |
|
|
1939 | fds [i].revents = 0; |
|
|
1940 | ev_io_start (loop, iow + i); |
|
|
1941 | } |
|
|
1942 | } |
|
|
1943 | |
|
|
1944 | // stop all watchers after blocking |
|
|
1945 | static void |
|
|
1946 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1947 | { |
|
|
1948 | ev_timer_stop (loop, &tw); |
|
|
1949 | |
|
|
1950 | for (int i = 0; i < nfd; ++i) |
|
|
1951 | { |
|
|
1952 | // set the relevant poll flags |
|
|
1953 | // could also call adns_processreadable etc. here |
|
|
1954 | struct pollfd *fd = fds + i; |
|
|
1955 | int revents = ev_clear_pending (iow + i); |
|
|
1956 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1957 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1958 | |
|
|
1959 | // now stop the watcher |
|
|
1960 | ev_io_stop (loop, iow + i); |
|
|
1961 | } |
|
|
1962 | |
|
|
1963 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1964 | } |
|
|
1965 | |
|
|
1966 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1967 | in the prepare watcher and would dispose of the check watcher. |
|
|
1968 | |
|
|
1969 | Method 3: If the module to be embedded supports explicit event |
|
|
1970 | notification (adns does), you can also make use of the actual watcher |
|
|
1971 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1972 | |
|
|
1973 | static void |
|
|
1974 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1975 | { |
|
|
1976 | adns_state ads = (adns_state)w->data; |
|
|
1977 | update_now (EV_A); |
|
|
1978 | |
|
|
1979 | adns_processtimeouts (ads, &tv_now); |
|
|
1980 | } |
|
|
1981 | |
|
|
1982 | static void |
|
|
1983 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1984 | { |
|
|
1985 | adns_state ads = (adns_state)w->data; |
|
|
1986 | update_now (EV_A); |
|
|
1987 | |
|
|
1988 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1989 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1990 | } |
|
|
1991 | |
|
|
1992 | // do not ever call adns_afterpoll |
|
|
1993 | |
|
|
1994 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1995 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1996 | their poll function. The drawback with this solution is that the main |
|
|
1997 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1998 | this. |
|
|
1999 | |
|
|
2000 | static gint |
|
|
2001 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2002 | { |
|
|
2003 | int got_events = 0; |
|
|
2004 | |
|
|
2005 | for (n = 0; n < nfds; ++n) |
|
|
2006 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2007 | |
|
|
2008 | if (timeout >= 0) |
|
|
2009 | // create/start timer |
|
|
2010 | |
|
|
2011 | // poll |
|
|
2012 | ev_loop (EV_A_ 0); |
|
|
2013 | |
|
|
2014 | // stop timer again |
|
|
2015 | if (timeout >= 0) |
|
|
2016 | ev_timer_stop (EV_A_ &to); |
|
|
2017 | |
|
|
2018 | // stop io watchers again - their callbacks should have set |
|
|
2019 | for (n = 0; n < nfds; ++n) |
|
|
2020 | ev_io_stop (EV_A_ iow [n]); |
|
|
2021 | |
|
|
2022 | return got_events; |
|
|
2023 | } |
1143 | |
2024 | |
1144 | |
2025 | |
1145 | =head2 C<ev_embed> - when one backend isn't enough... |
2026 | =head2 C<ev_embed> - when one backend isn't enough... |
1146 | |
2027 | |
1147 | This is a rather advanced watcher type that lets you embed one event loop |
2028 | This is a rather advanced watcher type that lets you embed one event loop |
… | |
… | |
1189 | portable one. |
2070 | portable one. |
1190 | |
2071 | |
1191 | So when you want to use this feature you will always have to be prepared |
2072 | So when you want to use this feature you will always have to be prepared |
1192 | that you cannot get an embeddable loop. The recommended way to get around |
2073 | that you cannot get an embeddable loop. The recommended way to get around |
1193 | this is to have a separate variables for your embeddable loop, try to |
2074 | this is to have a separate variables for your embeddable loop, try to |
1194 | create it, and if that fails, use the normal loop for everything: |
2075 | create it, and if that fails, use the normal loop for everything. |
|
|
2076 | |
|
|
2077 | =head3 Watcher-Specific Functions and Data Members |
|
|
2078 | |
|
|
2079 | =over 4 |
|
|
2080 | |
|
|
2081 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2082 | |
|
|
2083 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2084 | |
|
|
2085 | Configures the watcher to embed the given loop, which must be |
|
|
2086 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
2087 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
2088 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
2089 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
2090 | |
|
|
2091 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
2092 | |
|
|
2093 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
2094 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
2095 | apropriate way for embedded loops. |
|
|
2096 | |
|
|
2097 | =item struct ev_loop *other [read-only] |
|
|
2098 | |
|
|
2099 | The embedded event loop. |
|
|
2100 | |
|
|
2101 | =back |
|
|
2102 | |
|
|
2103 | =head3 Examples |
|
|
2104 | |
|
|
2105 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2106 | event loop. If that is not possible, use the default loop. The default |
|
|
2107 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
2108 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
2109 | used). |
1195 | |
2110 | |
1196 | struct ev_loop *loop_hi = ev_default_init (0); |
2111 | struct ev_loop *loop_hi = ev_default_init (0); |
1197 | struct ev_loop *loop_lo = 0; |
2112 | struct ev_loop *loop_lo = 0; |
1198 | struct ev_embed embed; |
2113 | struct ev_embed embed; |
1199 | |
2114 | |
… | |
… | |
1210 | ev_embed_start (loop_hi, &embed); |
2125 | ev_embed_start (loop_hi, &embed); |
1211 | } |
2126 | } |
1212 | else |
2127 | else |
1213 | loop_lo = loop_hi; |
2128 | loop_lo = loop_hi; |
1214 | |
2129 | |
|
|
2130 | Example: Check if kqueue is available but not recommended and create |
|
|
2131 | a kqueue backend for use with sockets (which usually work with any |
|
|
2132 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2133 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
|
|
2134 | |
|
|
2135 | struct ev_loop *loop = ev_default_init (0); |
|
|
2136 | struct ev_loop *loop_socket = 0; |
|
|
2137 | struct ev_embed embed; |
|
|
2138 | |
|
|
2139 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2140 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2141 | { |
|
|
2142 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2143 | ev_embed_start (loop, &embed); |
|
|
2144 | } |
|
|
2145 | |
|
|
2146 | if (!loop_socket) |
|
|
2147 | loop_socket = loop; |
|
|
2148 | |
|
|
2149 | // now use loop_socket for all sockets, and loop for everything else |
|
|
2150 | |
|
|
2151 | |
|
|
2152 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
2153 | |
|
|
2154 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
2155 | whoever is a good citizen cared to tell libev about it by calling |
|
|
2156 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
2157 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
2158 | and only in the child after the fork. If whoever good citizen calling |
|
|
2159 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
2160 | handlers will be invoked, too, of course. |
|
|
2161 | |
|
|
2162 | =head3 Watcher-Specific Functions and Data Members |
|
|
2163 | |
1215 | =over 4 |
2164 | =over 4 |
1216 | |
2165 | |
1217 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2166 | =item ev_fork_init (ev_signal *, callback) |
1218 | |
2167 | |
1219 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2168 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
2169 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
2170 | believe me. |
1220 | |
2171 | |
1221 | Configures the watcher to embed the given loop, which must be |
2172 | =back |
1222 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1223 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1224 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1225 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1226 | |
2173 | |
1227 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1228 | |
2174 | |
1229 | Make a single, non-blocking sweep over the embedded loop. This works |
2175 | =head2 C<ev_async> - how to wake up another event loop |
1230 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2176 | |
1231 | apropriate way for embedded loops. |
2177 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2178 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2179 | loops - those are of course safe to use in different threads). |
|
|
2180 | |
|
|
2181 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2182 | control, for example because it belongs to another thread. This is what |
|
|
2183 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2184 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2185 | safe. |
|
|
2186 | |
|
|
2187 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2188 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2189 | (i.e. the number of callback invocations may be less than the number of |
|
|
2190 | C<ev_async_sent> calls). |
|
|
2191 | |
|
|
2192 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2193 | just the default loop. |
|
|
2194 | |
|
|
2195 | =head3 Queueing |
|
|
2196 | |
|
|
2197 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2198 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2199 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2200 | need elaborate support such as pthreads. |
|
|
2201 | |
|
|
2202 | That means that if you want to queue data, you have to provide your own |
|
|
2203 | queue. But at least I can tell you would implement locking around your |
|
|
2204 | queue: |
|
|
2205 | |
|
|
2206 | =over 4 |
|
|
2207 | |
|
|
2208 | =item queueing from a signal handler context |
|
|
2209 | |
|
|
2210 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2211 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2212 | some fictitiuous SIGUSR1 handler: |
|
|
2213 | |
|
|
2214 | static ev_async mysig; |
|
|
2215 | |
|
|
2216 | static void |
|
|
2217 | sigusr1_handler (void) |
|
|
2218 | { |
|
|
2219 | sometype data; |
|
|
2220 | |
|
|
2221 | // no locking etc. |
|
|
2222 | queue_put (data); |
|
|
2223 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2224 | } |
|
|
2225 | |
|
|
2226 | static void |
|
|
2227 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2228 | { |
|
|
2229 | sometype data; |
|
|
2230 | sigset_t block, prev; |
|
|
2231 | |
|
|
2232 | sigemptyset (&block); |
|
|
2233 | sigaddset (&block, SIGUSR1); |
|
|
2234 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2235 | |
|
|
2236 | while (queue_get (&data)) |
|
|
2237 | process (data); |
|
|
2238 | |
|
|
2239 | if (sigismember (&prev, SIGUSR1) |
|
|
2240 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2241 | } |
|
|
2242 | |
|
|
2243 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2244 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2245 | either...). |
|
|
2246 | |
|
|
2247 | =item queueing from a thread context |
|
|
2248 | |
|
|
2249 | The strategy for threads is different, as you cannot (easily) block |
|
|
2250 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2251 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2252 | |
|
|
2253 | static ev_async mysig; |
|
|
2254 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2255 | |
|
|
2256 | static void |
|
|
2257 | otherthread (void) |
|
|
2258 | { |
|
|
2259 | // only need to lock the actual queueing operation |
|
|
2260 | pthread_mutex_lock (&mymutex); |
|
|
2261 | queue_put (data); |
|
|
2262 | pthread_mutex_unlock (&mymutex); |
|
|
2263 | |
|
|
2264 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2265 | } |
|
|
2266 | |
|
|
2267 | static void |
|
|
2268 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2269 | { |
|
|
2270 | pthread_mutex_lock (&mymutex); |
|
|
2271 | |
|
|
2272 | while (queue_get (&data)) |
|
|
2273 | process (data); |
|
|
2274 | |
|
|
2275 | pthread_mutex_unlock (&mymutex); |
|
|
2276 | } |
|
|
2277 | |
|
|
2278 | =back |
|
|
2279 | |
|
|
2280 | |
|
|
2281 | =head3 Watcher-Specific Functions and Data Members |
|
|
2282 | |
|
|
2283 | =over 4 |
|
|
2284 | |
|
|
2285 | =item ev_async_init (ev_async *, callback) |
|
|
2286 | |
|
|
2287 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2288 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2289 | believe me. |
|
|
2290 | |
|
|
2291 | =item ev_async_send (loop, ev_async *) |
|
|
2292 | |
|
|
2293 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2294 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2295 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2296 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2297 | section below on what exactly this means). |
|
|
2298 | |
|
|
2299 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2300 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2301 | calls to C<ev_async_send>. |
|
|
2302 | |
|
|
2303 | =item bool = ev_async_pending (ev_async *) |
|
|
2304 | |
|
|
2305 | Returns a non-zero value when C<ev_async_send> has been called on the |
|
|
2306 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2307 | event loop. |
|
|
2308 | |
|
|
2309 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
|
|
2310 | the loop iterates next and checks for the watcher to have become active, |
|
|
2311 | it will reset the flag again. C<ev_async_pending> can be used to very |
|
|
2312 | quickly check wether invoking the loop might be a good idea. |
|
|
2313 | |
|
|
2314 | Not that this does I<not> check wether the watcher itself is pending, only |
|
|
2315 | wether it has been requested to make this watcher pending. |
1232 | |
2316 | |
1233 | =back |
2317 | =back |
1234 | |
2318 | |
1235 | |
2319 | |
1236 | =head1 OTHER FUNCTIONS |
2320 | =head1 OTHER FUNCTIONS |
… | |
… | |
1308 | |
2392 | |
1309 | =item * Priorities are not currently supported. Initialising priorities |
2393 | =item * Priorities are not currently supported. Initialising priorities |
1310 | will fail and all watchers will have the same priority, even though there |
2394 | will fail and all watchers will have the same priority, even though there |
1311 | is an ev_pri field. |
2395 | is an ev_pri field. |
1312 | |
2396 | |
|
|
2397 | =item * In libevent, the last base created gets the signals, in libev, the |
|
|
2398 | first base created (== the default loop) gets the signals. |
|
|
2399 | |
1313 | =item * Other members are not supported. |
2400 | =item * Other members are not supported. |
1314 | |
2401 | |
1315 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
2402 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
1316 | to use the libev header file and library. |
2403 | to use the libev header file and library. |
1317 | |
2404 | |
… | |
… | |
1325 | |
2412 | |
1326 | To use it, |
2413 | To use it, |
1327 | |
2414 | |
1328 | #include <ev++.h> |
2415 | #include <ev++.h> |
1329 | |
2416 | |
1330 | (it is not installed by default). This automatically includes F<ev.h> |
2417 | This automatically includes F<ev.h> and puts all of its definitions (many |
1331 | and puts all of its definitions (many of them macros) into the global |
2418 | of them macros) into the global namespace. All C++ specific things are |
1332 | namespace. All C++ specific things are put into the C<ev> namespace. |
2419 | put into the C<ev> namespace. It should support all the same embedding |
|
|
2420 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1333 | |
2421 | |
1334 | It should support all the same embedding options as F<ev.h>, most notably |
2422 | Care has been taken to keep the overhead low. The only data member the C++ |
1335 | C<EV_MULTIPLICITY>. |
2423 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2424 | that the watcher is associated with (or no additional members at all if |
|
|
2425 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2426 | |
|
|
2427 | Currently, functions, and static and non-static member functions can be |
|
|
2428 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2429 | need one additional pointer for context. If you need support for other |
|
|
2430 | types of functors please contact the author (preferably after implementing |
|
|
2431 | it). |
1336 | |
2432 | |
1337 | Here is a list of things available in the C<ev> namespace: |
2433 | Here is a list of things available in the C<ev> namespace: |
1338 | |
2434 | |
1339 | =over 4 |
2435 | =over 4 |
1340 | |
2436 | |
… | |
… | |
1356 | |
2452 | |
1357 | All of those classes have these methods: |
2453 | All of those classes have these methods: |
1358 | |
2454 | |
1359 | =over 4 |
2455 | =over 4 |
1360 | |
2456 | |
1361 | =item ev::TYPE::TYPE (object *, object::method *) |
2457 | =item ev::TYPE::TYPE () |
1362 | |
2458 | |
1363 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2459 | =item ev::TYPE::TYPE (struct ev_loop *) |
1364 | |
2460 | |
1365 | =item ev::TYPE::~TYPE |
2461 | =item ev::TYPE::~TYPE |
1366 | |
2462 | |
1367 | The constructor takes a pointer to an object and a method pointer to |
2463 | The constructor (optionally) takes an event loop to associate the watcher |
1368 | the event handler callback to call in this class. The constructor calls |
2464 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1369 | C<ev_init> for you, which means you have to call the C<set> method |
2465 | |
1370 | before starting it. If you do not specify a loop then the constructor |
2466 | The constructor calls C<ev_init> for you, which means you have to call the |
1371 | automatically associates the default loop with this watcher. |
2467 | C<set> method before starting it. |
|
|
2468 | |
|
|
2469 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2470 | method to set a callback before you can start the watcher. |
|
|
2471 | |
|
|
2472 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2473 | not allow explicit template arguments for constructors). |
1372 | |
2474 | |
1373 | The destructor automatically stops the watcher if it is active. |
2475 | The destructor automatically stops the watcher if it is active. |
|
|
2476 | |
|
|
2477 | =item w->set<class, &class::method> (object *) |
|
|
2478 | |
|
|
2479 | This method sets the callback method to call. The method has to have a |
|
|
2480 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2481 | first argument and the C<revents> as second. The object must be given as |
|
|
2482 | parameter and is stored in the C<data> member of the watcher. |
|
|
2483 | |
|
|
2484 | This method synthesizes efficient thunking code to call your method from |
|
|
2485 | the C callback that libev requires. If your compiler can inline your |
|
|
2486 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2487 | your compiler is good :), then the method will be fully inlined into the |
|
|
2488 | thunking function, making it as fast as a direct C callback. |
|
|
2489 | |
|
|
2490 | Example: simple class declaration and watcher initialisation |
|
|
2491 | |
|
|
2492 | struct myclass |
|
|
2493 | { |
|
|
2494 | void io_cb (ev::io &w, int revents) { } |
|
|
2495 | } |
|
|
2496 | |
|
|
2497 | myclass obj; |
|
|
2498 | ev::io iow; |
|
|
2499 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2500 | |
|
|
2501 | =item w->set<function> (void *data = 0) |
|
|
2502 | |
|
|
2503 | Also sets a callback, but uses a static method or plain function as |
|
|
2504 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2505 | C<data> member and is free for you to use. |
|
|
2506 | |
|
|
2507 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2508 | |
|
|
2509 | See the method-C<set> above for more details. |
|
|
2510 | |
|
|
2511 | Example: |
|
|
2512 | |
|
|
2513 | static void io_cb (ev::io &w, int revents) { } |
|
|
2514 | iow.set <io_cb> (); |
1374 | |
2515 | |
1375 | =item w->set (struct ev_loop *) |
2516 | =item w->set (struct ev_loop *) |
1376 | |
2517 | |
1377 | Associates a different C<struct ev_loop> with this watcher. You can only |
2518 | Associates a different C<struct ev_loop> with this watcher. You can only |
1378 | do this when the watcher is inactive (and not pending either). |
2519 | do this when the watcher is inactive (and not pending either). |
1379 | |
2520 | |
1380 | =item w->set ([args]) |
2521 | =item w->set ([args]) |
1381 | |
2522 | |
1382 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2523 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1383 | called at least once. Unlike the C counterpart, an active watcher gets |
2524 | called at least once. Unlike the C counterpart, an active watcher gets |
1384 | automatically stopped and restarted. |
2525 | automatically stopped and restarted when reconfiguring it with this |
|
|
2526 | method. |
1385 | |
2527 | |
1386 | =item w->start () |
2528 | =item w->start () |
1387 | |
2529 | |
1388 | Starts the watcher. Note that there is no C<loop> argument as the |
2530 | Starts the watcher. Note that there is no C<loop> argument, as the |
1389 | constructor already takes the loop. |
2531 | constructor already stores the event loop. |
1390 | |
2532 | |
1391 | =item w->stop () |
2533 | =item w->stop () |
1392 | |
2534 | |
1393 | Stops the watcher if it is active. Again, no C<loop> argument. |
2535 | Stops the watcher if it is active. Again, no C<loop> argument. |
1394 | |
2536 | |
1395 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2537 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1396 | |
2538 | |
1397 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2539 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1398 | C<ev_TYPE_again> function. |
2540 | C<ev_TYPE_again> function. |
1399 | |
2541 | |
1400 | =item w->sweep () C<ev::embed> only |
2542 | =item w->sweep () (C<ev::embed> only) |
1401 | |
2543 | |
1402 | Invokes C<ev_embed_sweep>. |
2544 | Invokes C<ev_embed_sweep>. |
|
|
2545 | |
|
|
2546 | =item w->update () (C<ev::stat> only) |
|
|
2547 | |
|
|
2548 | Invokes C<ev_stat_stat>. |
1403 | |
2549 | |
1404 | =back |
2550 | =back |
1405 | |
2551 | |
1406 | =back |
2552 | =back |
1407 | |
2553 | |
1408 | Example: Define a class with an IO and idle watcher, start one of them in |
2554 | Example: Define a class with an IO and idle watcher, start one of them in |
1409 | the constructor. |
2555 | the constructor. |
1410 | |
2556 | |
1411 | class myclass |
2557 | class myclass |
1412 | { |
2558 | { |
1413 | ev_io io; void io_cb (ev::io &w, int revents); |
2559 | ev::io io; void io_cb (ev::io &w, int revents); |
1414 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2560 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
1415 | |
2561 | |
1416 | myclass (); |
2562 | myclass (int fd) |
|
|
2563 | { |
|
|
2564 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2565 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2566 | |
|
|
2567 | io.start (fd, ev::READ); |
|
|
2568 | } |
|
|
2569 | }; |
|
|
2570 | |
|
|
2571 | |
|
|
2572 | =head1 OTHER LANGUAGE BINDINGS |
|
|
2573 | |
|
|
2574 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2575 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2576 | any interesting language binding in addition to the ones listed here, drop |
|
|
2577 | me a note. |
|
|
2578 | |
|
|
2579 | =over 4 |
|
|
2580 | |
|
|
2581 | =item Perl |
|
|
2582 | |
|
|
2583 | The EV module implements the full libev API and is actually used to test |
|
|
2584 | libev. EV is developed together with libev. Apart from the EV core module, |
|
|
2585 | there are additional modules that implement libev-compatible interfaces |
|
|
2586 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
|
|
2587 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
|
|
2588 | |
|
|
2589 | It can be found and installed via CPAN, its homepage is found at |
|
|
2590 | L<http://software.schmorp.de/pkg/EV>. |
|
|
2591 | |
|
|
2592 | =item Ruby |
|
|
2593 | |
|
|
2594 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2595 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
|
|
2596 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2597 | L<http://rev.rubyforge.org/>. |
|
|
2598 | |
|
|
2599 | =item D |
|
|
2600 | |
|
|
2601 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
|
|
2602 | be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2603 | |
|
|
2604 | =back |
|
|
2605 | |
|
|
2606 | |
|
|
2607 | =head1 MACRO MAGIC |
|
|
2608 | |
|
|
2609 | Libev can be compiled with a variety of options, the most fundamantal |
|
|
2610 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
|
|
2611 | functions and callbacks have an initial C<struct ev_loop *> argument. |
|
|
2612 | |
|
|
2613 | To make it easier to write programs that cope with either variant, the |
|
|
2614 | following macros are defined: |
|
|
2615 | |
|
|
2616 | =over 4 |
|
|
2617 | |
|
|
2618 | =item C<EV_A>, C<EV_A_> |
|
|
2619 | |
|
|
2620 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
2621 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
2622 | C<EV_A_> is used when other arguments are following. Example: |
|
|
2623 | |
|
|
2624 | ev_unref (EV_A); |
|
|
2625 | ev_timer_add (EV_A_ watcher); |
|
|
2626 | ev_loop (EV_A_ 0); |
|
|
2627 | |
|
|
2628 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
2629 | which is often provided by the following macro. |
|
|
2630 | |
|
|
2631 | =item C<EV_P>, C<EV_P_> |
|
|
2632 | |
|
|
2633 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
2634 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
2635 | C<EV_P_> is used when other parameters are following. Example: |
|
|
2636 | |
|
|
2637 | // this is how ev_unref is being declared |
|
|
2638 | static void ev_unref (EV_P); |
|
|
2639 | |
|
|
2640 | // this is how you can declare your typical callback |
|
|
2641 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
2642 | |
|
|
2643 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
2644 | suitable for use with C<EV_A>. |
|
|
2645 | |
|
|
2646 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
2647 | |
|
|
2648 | Similar to the other two macros, this gives you the value of the default |
|
|
2649 | loop, if multiple loops are supported ("ev loop default"). |
|
|
2650 | |
|
|
2651 | =item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_> |
|
|
2652 | |
|
|
2653 | Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the |
|
|
2654 | default loop has been initialised (C<UC> == unchecked). Their behaviour |
|
|
2655 | is undefined when the default loop has not been initialised by a previous |
|
|
2656 | execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>. |
|
|
2657 | |
|
|
2658 | It is often prudent to use C<EV_DEFAULT> when initialising the first |
|
|
2659 | watcher in a function but use C<EV_DEFAULT_UC> afterwards. |
|
|
2660 | |
|
|
2661 | =back |
|
|
2662 | |
|
|
2663 | Example: Declare and initialise a check watcher, utilising the above |
|
|
2664 | macros so it will work regardless of whether multiple loops are supported |
|
|
2665 | or not. |
|
|
2666 | |
|
|
2667 | static void |
|
|
2668 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
2669 | { |
|
|
2670 | ev_check_stop (EV_A_ w); |
1417 | } |
2671 | } |
1418 | |
2672 | |
1419 | myclass::myclass (int fd) |
2673 | ev_check check; |
1420 | : io (this, &myclass::io_cb), |
2674 | ev_check_init (&check, check_cb); |
1421 | idle (this, &myclass::idle_cb) |
2675 | ev_check_start (EV_DEFAULT_ &check); |
1422 | { |
2676 | ev_loop (EV_DEFAULT_ 0); |
1423 | io.start (fd, ev::READ); |
|
|
1424 | } |
|
|
1425 | |
2677 | |
1426 | =head1 EMBEDDING |
2678 | =head1 EMBEDDING |
1427 | |
2679 | |
1428 | Libev can (and often is) directly embedded into host |
2680 | Libev can (and often is) directly embedded into host |
1429 | applications. Examples of applications that embed it include the Deliantra |
2681 | applications. Examples of applications that embed it include the Deliantra |
1430 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2682 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1431 | and rxvt-unicode. |
2683 | and rxvt-unicode. |
1432 | |
2684 | |
1433 | The goal is to enable you to just copy the neecssary files into your |
2685 | The goal is to enable you to just copy the necessary files into your |
1434 | source directory without having to change even a single line in them, so |
2686 | source directory without having to change even a single line in them, so |
1435 | you can easily upgrade by simply copying (or having a checked-out copy of |
2687 | you can easily upgrade by simply copying (or having a checked-out copy of |
1436 | libev somewhere in your source tree). |
2688 | libev somewhere in your source tree). |
1437 | |
2689 | |
1438 | =head2 FILESETS |
2690 | =head2 FILESETS |
… | |
… | |
1469 | ev_vars.h |
2721 | ev_vars.h |
1470 | ev_wrap.h |
2722 | ev_wrap.h |
1471 | |
2723 | |
1472 | ev_win32.c required on win32 platforms only |
2724 | ev_win32.c required on win32 platforms only |
1473 | |
2725 | |
1474 | ev_select.c only when select backend is enabled (which is by default) |
2726 | ev_select.c only when select backend is enabled (which is enabled by default) |
1475 | ev_poll.c only when poll backend is enabled (disabled by default) |
2727 | ev_poll.c only when poll backend is enabled (disabled by default) |
1476 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2728 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1477 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2729 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1478 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2730 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1479 | |
2731 | |
… | |
… | |
1508 | |
2760 | |
1509 | libev.m4 |
2761 | libev.m4 |
1510 | |
2762 | |
1511 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2763 | =head2 PREPROCESSOR SYMBOLS/MACROS |
1512 | |
2764 | |
1513 | Libev can be configured via a variety of preprocessor symbols you have to define |
2765 | Libev can be configured via a variety of preprocessor symbols you have to |
1514 | before including any of its files. The default is not to build for multiplicity |
2766 | define before including any of its files. The default in the absense of |
1515 | and only include the select backend. |
2767 | autoconf is noted for every option. |
1516 | |
2768 | |
1517 | =over 4 |
2769 | =over 4 |
1518 | |
2770 | |
1519 | =item EV_STANDALONE |
2771 | =item EV_STANDALONE |
1520 | |
2772 | |
… | |
… | |
1528 | |
2780 | |
1529 | If defined to be C<1>, libev will try to detect the availability of the |
2781 | If defined to be C<1>, libev will try to detect the availability of the |
1530 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2782 | monotonic clock option at both compiletime and runtime. Otherwise no use |
1531 | of the monotonic clock option will be attempted. If you enable this, you |
2783 | of the monotonic clock option will be attempted. If you enable this, you |
1532 | usually have to link against librt or something similar. Enabling it when |
2784 | usually have to link against librt or something similar. Enabling it when |
1533 | the functionality isn't available is safe, though, althoguh you have |
2785 | the functionality isn't available is safe, though, although you have |
1534 | to make sure you link against any libraries where the C<clock_gettime> |
2786 | to make sure you link against any libraries where the C<clock_gettime> |
1535 | function is hiding in (often F<-lrt>). |
2787 | function is hiding in (often F<-lrt>). |
1536 | |
2788 | |
1537 | =item EV_USE_REALTIME |
2789 | =item EV_USE_REALTIME |
1538 | |
2790 | |
1539 | If defined to be C<1>, libev will try to detect the availability of the |
2791 | If defined to be C<1>, libev will try to detect the availability of the |
1540 | realtime clock option at compiletime (and assume its availability at |
2792 | realtime clock option at compiletime (and assume its availability at |
1541 | runtime if successful). Otherwise no use of the realtime clock option will |
2793 | runtime if successful). Otherwise no use of the realtime clock option will |
1542 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2794 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
1543 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2795 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
1544 | in the description of C<EV_USE_MONOTONIC>, though. |
2796 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2797 | |
|
|
2798 | =item EV_USE_NANOSLEEP |
|
|
2799 | |
|
|
2800 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2801 | and will use it for delays. Otherwise it will use C<select ()>. |
|
|
2802 | |
|
|
2803 | =item EV_USE_EVENTFD |
|
|
2804 | |
|
|
2805 | If defined to be C<1>, then libev will assume that C<eventfd ()> is |
|
|
2806 | available and will probe for kernel support at runtime. This will improve |
|
|
2807 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
|
|
2808 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
2809 | 2.7 or newer, otherwise disabled. |
1545 | |
2810 | |
1546 | =item EV_USE_SELECT |
2811 | =item EV_USE_SELECT |
1547 | |
2812 | |
1548 | If undefined or defined to be C<1>, libev will compile in support for the |
2813 | If undefined or defined to be C<1>, libev will compile in support for the |
1549 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2814 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
1568 | be used is the winsock select). This means that it will call |
2833 | be used is the winsock select). This means that it will call |
1569 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2834 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
1570 | it is assumed that all these functions actually work on fds, even |
2835 | it is assumed that all these functions actually work on fds, even |
1571 | on win32. Should not be defined on non-win32 platforms. |
2836 | on win32. Should not be defined on non-win32 platforms. |
1572 | |
2837 | |
|
|
2838 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2839 | |
|
|
2840 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2841 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2842 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2843 | correct. In some cases, programs use their own file descriptor management, |
|
|
2844 | in which case they can provide this function to map fds to socket handles. |
|
|
2845 | |
1573 | =item EV_USE_POLL |
2846 | =item EV_USE_POLL |
1574 | |
2847 | |
1575 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2848 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
1576 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2849 | backend. Otherwise it will be enabled on non-win32 platforms. It |
1577 | takes precedence over select. |
2850 | takes precedence over select. |
1578 | |
2851 | |
1579 | =item EV_USE_EPOLL |
2852 | =item EV_USE_EPOLL |
1580 | |
2853 | |
1581 | If defined to be C<1>, libev will compile in support for the Linux |
2854 | If defined to be C<1>, libev will compile in support for the Linux |
1582 | C<epoll>(7) backend. Its availability will be detected at runtime, |
2855 | C<epoll>(7) backend. Its availability will be detected at runtime, |
1583 | otherwise another method will be used as fallback. This is the |
2856 | otherwise another method will be used as fallback. This is the preferred |
1584 | preferred backend for GNU/Linux systems. |
2857 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
2858 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
1585 | |
2859 | |
1586 | =item EV_USE_KQUEUE |
2860 | =item EV_USE_KQUEUE |
1587 | |
2861 | |
1588 | If defined to be C<1>, libev will compile in support for the BSD style |
2862 | If defined to be C<1>, libev will compile in support for the BSD style |
1589 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
2863 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
1604 | |
2878 | |
1605 | =item EV_USE_DEVPOLL |
2879 | =item EV_USE_DEVPOLL |
1606 | |
2880 | |
1607 | reserved for future expansion, works like the USE symbols above. |
2881 | reserved for future expansion, works like the USE symbols above. |
1608 | |
2882 | |
|
|
2883 | =item EV_USE_INOTIFY |
|
|
2884 | |
|
|
2885 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2886 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2887 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
2888 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
2889 | |
|
|
2890 | =item EV_ATOMIC_T |
|
|
2891 | |
|
|
2892 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2893 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2894 | type is easily found in the C language, so you can provide your own type |
|
|
2895 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2896 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2897 | |
|
|
2898 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2899 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2900 | |
1609 | =item EV_H |
2901 | =item EV_H |
1610 | |
2902 | |
1611 | The name of the F<ev.h> header file used to include it. The default if |
2903 | The name of the F<ev.h> header file used to include it. The default if |
1612 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2904 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
1613 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2905 | used to virtually rename the F<ev.h> header file in case of conflicts. |
1614 | |
2906 | |
1615 | =item EV_CONFIG_H |
2907 | =item EV_CONFIG_H |
1616 | |
2908 | |
1617 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2909 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
1618 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2910 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
1619 | C<EV_H>, above. |
2911 | C<EV_H>, above. |
1620 | |
2912 | |
1621 | =item EV_EVENT_H |
2913 | =item EV_EVENT_H |
1622 | |
2914 | |
1623 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2915 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
1624 | of how the F<event.h> header can be found. |
2916 | of how the F<event.h> header can be found, the default is C<"event.h">. |
1625 | |
2917 | |
1626 | =item EV_PROTOTYPES |
2918 | =item EV_PROTOTYPES |
1627 | |
2919 | |
1628 | If defined to be C<0>, then F<ev.h> will not define any function |
2920 | If defined to be C<0>, then F<ev.h> will not define any function |
1629 | prototypes, but still define all the structs and other symbols. This is |
2921 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
1636 | will have the C<struct ev_loop *> as first argument, and you can create |
2928 | will have the C<struct ev_loop *> as first argument, and you can create |
1637 | additional independent event loops. Otherwise there will be no support |
2929 | additional independent event loops. Otherwise there will be no support |
1638 | for multiple event loops and there is no first event loop pointer |
2930 | for multiple event loops and there is no first event loop pointer |
1639 | argument. Instead, all functions act on the single default loop. |
2931 | argument. Instead, all functions act on the single default loop. |
1640 | |
2932 | |
|
|
2933 | =item EV_MINPRI |
|
|
2934 | |
|
|
2935 | =item EV_MAXPRI |
|
|
2936 | |
|
|
2937 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2938 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2939 | provide for more priorities by overriding those symbols (usually defined |
|
|
2940 | to be C<-2> and C<2>, respectively). |
|
|
2941 | |
|
|
2942 | When doing priority-based operations, libev usually has to linearly search |
|
|
2943 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2944 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2945 | fine. |
|
|
2946 | |
|
|
2947 | If your embedding app does not need any priorities, defining these both to |
|
|
2948 | C<0> will save some memory and cpu. |
|
|
2949 | |
1641 | =item EV_PERIODICS |
2950 | =item EV_PERIODIC_ENABLE |
1642 | |
2951 | |
1643 | If undefined or defined to be C<1>, then periodic timers are supported, |
2952 | If undefined or defined to be C<1>, then periodic timers are supported. If |
1644 | otherwise not. This saves a few kb of code. |
2953 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2954 | code. |
|
|
2955 | |
|
|
2956 | =item EV_IDLE_ENABLE |
|
|
2957 | |
|
|
2958 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2959 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2960 | code. |
|
|
2961 | |
|
|
2962 | =item EV_EMBED_ENABLE |
|
|
2963 | |
|
|
2964 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2965 | defined to be C<0>, then they are not. |
|
|
2966 | |
|
|
2967 | =item EV_STAT_ENABLE |
|
|
2968 | |
|
|
2969 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2970 | defined to be C<0>, then they are not. |
|
|
2971 | |
|
|
2972 | =item EV_FORK_ENABLE |
|
|
2973 | |
|
|
2974 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2975 | defined to be C<0>, then they are not. |
|
|
2976 | |
|
|
2977 | =item EV_ASYNC_ENABLE |
|
|
2978 | |
|
|
2979 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
2980 | defined to be C<0>, then they are not. |
|
|
2981 | |
|
|
2982 | =item EV_MINIMAL |
|
|
2983 | |
|
|
2984 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2985 | speed, define this symbol to C<1>. Currently this is used to override some |
|
|
2986 | inlining decisions, saves roughly 30% codesize of amd64. It also selects a |
|
|
2987 | much smaller 2-heap for timer management over the default 4-heap. |
|
|
2988 | |
|
|
2989 | =item EV_PID_HASHSIZE |
|
|
2990 | |
|
|
2991 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2992 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2993 | than enough. If you need to manage thousands of children you might want to |
|
|
2994 | increase this value (I<must> be a power of two). |
|
|
2995 | |
|
|
2996 | =item EV_INOTIFY_HASHSIZE |
|
|
2997 | |
|
|
2998 | C<ev_stat> watchers use a small hash table to distribute workload by |
|
|
2999 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
3000 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
3001 | watchers you might want to increase this value (I<must> be a power of |
|
|
3002 | two). |
|
|
3003 | |
|
|
3004 | =item EV_USE_4HEAP |
|
|
3005 | |
|
|
3006 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3007 | timer and periodics heap, libev uses a 4-heap when this symbol is defined |
|
|
3008 | to C<1>. The 4-heap uses more complicated (longer) code but has a |
|
|
3009 | noticable after performance with many (thousands) of watchers. |
|
|
3010 | |
|
|
3011 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
|
|
3012 | (disabled). |
|
|
3013 | |
|
|
3014 | =item EV_HEAP_CACHE_AT |
|
|
3015 | |
|
|
3016 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3017 | timer and periodics heap, libev can cache the timestamp (I<at>) within |
|
|
3018 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
|
|
3019 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3020 | but avoids random read accesses on heap changes. This noticably improves |
|
|
3021 | performance noticably with with many (hundreds) of watchers. |
|
|
3022 | |
|
|
3023 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
|
|
3024 | (disabled). |
1645 | |
3025 | |
1646 | =item EV_COMMON |
3026 | =item EV_COMMON |
1647 | |
3027 | |
1648 | By default, all watchers have a C<void *data> member. By redefining |
3028 | By default, all watchers have a C<void *data> member. By redefining |
1649 | this macro to a something else you can include more and other types of |
3029 | this macro to a something else you can include more and other types of |
… | |
… | |
1654 | |
3034 | |
1655 | #define EV_COMMON \ |
3035 | #define EV_COMMON \ |
1656 | SV *self; /* contains this struct */ \ |
3036 | SV *self; /* contains this struct */ \ |
1657 | SV *cb_sv, *fh /* note no trailing ";" */ |
3037 | SV *cb_sv, *fh /* note no trailing ";" */ |
1658 | |
3038 | |
1659 | =item EV_CB_DECLARE(type) |
3039 | =item EV_CB_DECLARE (type) |
1660 | |
3040 | |
1661 | =item EV_CB_INVOKE(watcher,revents) |
3041 | =item EV_CB_INVOKE (watcher, revents) |
1662 | |
3042 | |
1663 | =item ev_set_cb(ev,cb) |
3043 | =item ev_set_cb (ev, cb) |
1664 | |
3044 | |
1665 | Can be used to change the callback member declaration in each watcher, |
3045 | Can be used to change the callback member declaration in each watcher, |
1666 | and the way callbacks are invoked and set. Must expand to a struct member |
3046 | and the way callbacks are invoked and set. Must expand to a struct member |
1667 | definition and a statement, respectively. See the F<ev.v> header file for |
3047 | definition and a statement, respectively. See the F<ev.h> header file for |
1668 | their default definitions. One possible use for overriding these is to |
3048 | their default definitions. One possible use for overriding these is to |
1669 | avoid the ev_loop pointer as first argument in all cases, or to use method |
3049 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
1670 | calls instead of plain function calls in C++. |
3050 | method calls instead of plain function calls in C++. |
|
|
3051 | |
|
|
3052 | =head2 EXPORTED API SYMBOLS |
|
|
3053 | |
|
|
3054 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
3055 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
3056 | all public symbols, one per line: |
|
|
3057 | |
|
|
3058 | Symbols.ev for libev proper |
|
|
3059 | Symbols.event for the libevent emulation |
|
|
3060 | |
|
|
3061 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3062 | multiple versions of libev linked together (which is obviously bad in |
|
|
3063 | itself, but sometimes it is inconvinient to avoid this). |
|
|
3064 | |
|
|
3065 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
3066 | include before including F<ev.h>: |
|
|
3067 | |
|
|
3068 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3069 | |
|
|
3070 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
3071 | |
|
|
3072 | #define ev_backend myprefix_ev_backend |
|
|
3073 | #define ev_check_start myprefix_ev_check_start |
|
|
3074 | #define ev_check_stop myprefix_ev_check_stop |
|
|
3075 | ... |
1671 | |
3076 | |
1672 | =head2 EXAMPLES |
3077 | =head2 EXAMPLES |
1673 | |
3078 | |
1674 | For a real-world example of a program the includes libev |
3079 | For a real-world example of a program the includes libev |
1675 | verbatim, you can have a look at the EV perl module |
3080 | verbatim, you can have a look at the EV perl module |
… | |
… | |
1678 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
3083 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
1679 | will be compiled. It is pretty complex because it provides its own header |
3084 | will be compiled. It is pretty complex because it provides its own header |
1680 | file. |
3085 | file. |
1681 | |
3086 | |
1682 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3087 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
1683 | that everybody includes and which overrides some autoconf choices: |
3088 | that everybody includes and which overrides some configure choices: |
1684 | |
3089 | |
|
|
3090 | #define EV_MINIMAL 1 |
1685 | #define EV_USE_POLL 0 |
3091 | #define EV_USE_POLL 0 |
1686 | #define EV_MULTIPLICITY 0 |
3092 | #define EV_MULTIPLICITY 0 |
1687 | #define EV_PERIODICS 0 |
3093 | #define EV_PERIODIC_ENABLE 0 |
|
|
3094 | #define EV_STAT_ENABLE 0 |
|
|
3095 | #define EV_FORK_ENABLE 0 |
1688 | #define EV_CONFIG_H <config.h> |
3096 | #define EV_CONFIG_H <config.h> |
|
|
3097 | #define EV_MINPRI 0 |
|
|
3098 | #define EV_MAXPRI 0 |
1689 | |
3099 | |
1690 | #include "ev++.h" |
3100 | #include "ev++.h" |
1691 | |
3101 | |
1692 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3102 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
1693 | |
3103 | |
1694 | #include "ev_cpp.h" |
3104 | #include "ev_cpp.h" |
1695 | #include "ev.c" |
3105 | #include "ev.c" |
1696 | |
3106 | |
|
|
3107 | |
|
|
3108 | =head1 THREADS AND COROUTINES |
|
|
3109 | |
|
|
3110 | =head2 THREADS |
|
|
3111 | |
|
|
3112 | Libev itself is completely threadsafe, but it uses no locking. This |
|
|
3113 | means that you can use as many loops as you want in parallel, as long as |
|
|
3114 | only one thread ever calls into one libev function with the same loop |
|
|
3115 | parameter. |
|
|
3116 | |
|
|
3117 | Or put differently: calls with different loop parameters can be done in |
|
|
3118 | parallel from multiple threads, calls with the same loop parameter must be |
|
|
3119 | done serially (but can be done from different threads, as long as only one |
|
|
3120 | thread ever is inside a call at any point in time, e.g. by using a mutex |
|
|
3121 | per loop). |
|
|
3122 | |
|
|
3123 | If you want to know which design is best for your problem, then I cannot |
|
|
3124 | help you but by giving some generic advice: |
|
|
3125 | |
|
|
3126 | =over 4 |
|
|
3127 | |
|
|
3128 | =item * most applications have a main thread: use the default libev loop |
|
|
3129 | in that thread, or create a seperate thread running only the default loop. |
|
|
3130 | |
|
|
3131 | This helps integrating other libraries or software modules that use libev |
|
|
3132 | themselves and don't care/know about threading. |
|
|
3133 | |
|
|
3134 | =item * one loop per thread is usually a good model. |
|
|
3135 | |
|
|
3136 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3137 | exists, but it is always a good start. |
|
|
3138 | |
|
|
3139 | =item * other models exist, such as the leader/follower pattern, where one |
|
|
3140 | loop is handed through multiple threads in a kind of round-robbin fashion. |
|
|
3141 | |
|
|
3142 | Chosing a model is hard - look around, learn, know that usually you cna do |
|
|
3143 | better than you currently do :-) |
|
|
3144 | |
|
|
3145 | =item * often you need to talk to some other thread which blocks in the |
|
|
3146 | event loop - C<ev_async> watchers can be used to wake them up from other |
|
|
3147 | threads safely (or from signal contexts...). |
|
|
3148 | |
|
|
3149 | =back |
|
|
3150 | |
|
|
3151 | =head2 COROUTINES |
|
|
3152 | |
|
|
3153 | Libev is much more accomodating to coroutines ("cooperative threads"): |
|
|
3154 | libev fully supports nesting calls to it's functions from different |
|
|
3155 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
|
|
3156 | different coroutines and switch freely between both coroutines running the |
|
|
3157 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3158 | you must not do this from C<ev_periodic> reschedule callbacks. |
|
|
3159 | |
|
|
3160 | Care has been invested into making sure that libev does not keep local |
|
|
3161 | state inside C<ev_loop>, and other calls do not usually allow coroutine |
|
|
3162 | switches. |
|
|
3163 | |
|
|
3164 | |
|
|
3165 | =head1 COMPLEXITIES |
|
|
3166 | |
|
|
3167 | In this section the complexities of (many of) the algorithms used inside |
|
|
3168 | libev will be explained. For complexity discussions about backends see the |
|
|
3169 | documentation for C<ev_default_init>. |
|
|
3170 | |
|
|
3171 | All of the following are about amortised time: If an array needs to be |
|
|
3172 | extended, libev needs to realloc and move the whole array, but this |
|
|
3173 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
3174 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
3175 | it is much faster and asymptotically approaches constant time. |
|
|
3176 | |
|
|
3177 | =over 4 |
|
|
3178 | |
|
|
3179 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
3180 | |
|
|
3181 | This means that, when you have a watcher that triggers in one hour and |
|
|
3182 | there are 100 watchers that would trigger before that then inserting will |
|
|
3183 | have to skip roughly seven (C<ld 100>) of these watchers. |
|
|
3184 | |
|
|
3185 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
|
|
3186 | |
|
|
3187 | That means that changing a timer costs less than removing/adding them |
|
|
3188 | as only the relative motion in the event queue has to be paid for. |
|
|
3189 | |
|
|
3190 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
|
|
3191 | |
|
|
3192 | These just add the watcher into an array or at the head of a list. |
|
|
3193 | |
|
|
3194 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
|
|
3195 | |
|
|
3196 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
3197 | |
|
|
3198 | These watchers are stored in lists then need to be walked to find the |
|
|
3199 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
3200 | have many watchers waiting for the same fd or signal). |
|
|
3201 | |
|
|
3202 | =item Finding the next timer in each loop iteration: O(1) |
|
|
3203 | |
|
|
3204 | By virtue of using a binary or 4-heap, the next timer is always found at a |
|
|
3205 | fixed position in the storage array. |
|
|
3206 | |
|
|
3207 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
3208 | |
|
|
3209 | A change means an I/O watcher gets started or stopped, which requires |
|
|
3210 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3211 | on backend and wether C<ev_io_set> was used). |
|
|
3212 | |
|
|
3213 | =item Activating one watcher (putting it into the pending state): O(1) |
|
|
3214 | |
|
|
3215 | =item Priority handling: O(number_of_priorities) |
|
|
3216 | |
|
|
3217 | Priorities are implemented by allocating some space for each |
|
|
3218 | priority. When doing priority-based operations, libev usually has to |
|
|
3219 | linearly search all the priorities, but starting/stopping and activating |
|
|
3220 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3221 | |
|
|
3222 | =item Sending an ev_async: O(1) |
|
|
3223 | |
|
|
3224 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3225 | |
|
|
3226 | =item Processing signals: O(max_signal_number) |
|
|
3227 | |
|
|
3228 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3229 | calls in the current loop iteration. Checking for async and signal events |
|
|
3230 | involves iterating over all running async watchers or all signal numbers. |
|
|
3231 | |
|
|
3232 | =back |
|
|
3233 | |
|
|
3234 | |
|
|
3235 | =head1 Win32 platform limitations and workarounds |
|
|
3236 | |
|
|
3237 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
3238 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
3239 | model. Libev still offers limited functionality on this platform in |
|
|
3240 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
3241 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3242 | e.g. cygwin. |
|
|
3243 | |
|
|
3244 | Lifting these limitations would basically require the full |
|
|
3245 | re-implementation of the I/O system. If you are into these kinds of |
|
|
3246 | things, then note that glib does exactly that for you in a very portable |
|
|
3247 | way (note also that glib is the slowest event library known to man). |
|
|
3248 | |
|
|
3249 | There is no supported compilation method available on windows except |
|
|
3250 | embedding it into other applications. |
|
|
3251 | |
|
|
3252 | Due to the many, low, and arbitrary limits on the win32 platform and |
|
|
3253 | the abysmal performance of winsockets, using a large number of sockets |
|
|
3254 | is not recommended (and not reasonable). If your program needs to use |
|
|
3255 | more than a hundred or so sockets, then likely it needs to use a totally |
|
|
3256 | different implementation for windows, as libev offers the POSIX readyness |
|
|
3257 | notification model, which cannot be implemented efficiently on windows |
|
|
3258 | (microsoft monopoly games). |
|
|
3259 | |
|
|
3260 | =over 4 |
|
|
3261 | |
|
|
3262 | =item The winsocket select function |
|
|
3263 | |
|
|
3264 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
3265 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
3266 | very inefficient, and also requires a mapping from file descriptors |
|
|
3267 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
3268 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
3269 | symbols for more info. |
|
|
3270 | |
|
|
3271 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
3272 | libraries and raw winsocket select is: |
|
|
3273 | |
|
|
3274 | #define EV_USE_SELECT 1 |
|
|
3275 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3276 | |
|
|
3277 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3278 | complexity in the O(n²) range when using win32. |
|
|
3279 | |
|
|
3280 | =item Limited number of file descriptors |
|
|
3281 | |
|
|
3282 | Windows has numerous arbitrary (and low) limits on things. |
|
|
3283 | |
|
|
3284 | Early versions of winsocket's select only supported waiting for a maximum |
|
|
3285 | of C<64> handles (probably owning to the fact that all windows kernels |
|
|
3286 | can only wait for C<64> things at the same time internally; microsoft |
|
|
3287 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
3288 | previous thread in each. Great). |
|
|
3289 | |
|
|
3290 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3291 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3292 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3293 | select emulation on windows). |
|
|
3294 | |
|
|
3295 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3296 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3297 | or something like this inside microsoft). You can increase this by calling |
|
|
3298 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3299 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3300 | libraries. |
|
|
3301 | |
|
|
3302 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3303 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3304 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3305 | calling select (O(n²)) will likely make this unworkable. |
|
|
3306 | |
|
|
3307 | =back |
|
|
3308 | |
|
|
3309 | |
|
|
3310 | =head1 PORTABILITY REQUIREMENTS |
|
|
3311 | |
|
|
3312 | In addition to a working ISO-C implementation, libev relies on a few |
|
|
3313 | additional extensions: |
|
|
3314 | |
|
|
3315 | =over 4 |
|
|
3316 | |
|
|
3317 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
|
|
3318 | |
|
|
3319 | The type C<sig_atomic_t volatile> (or whatever is defined as |
|
|
3320 | C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different |
|
|
3321 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
|
|
3322 | believed to be sufficiently portable. |
|
|
3323 | |
|
|
3324 | =item C<sigprocmask> must work in a threaded environment |
|
|
3325 | |
|
|
3326 | Libev uses C<sigprocmask> to temporarily block signals. This is not |
|
|
3327 | allowed in a threaded program (C<pthread_sigmask> has to be used). Typical |
|
|
3328 | pthread implementations will either allow C<sigprocmask> in the "main |
|
|
3329 | thread" or will block signals process-wide, both behaviours would |
|
|
3330 | be compatible with libev. Interaction between C<sigprocmask> and |
|
|
3331 | C<pthread_sigmask> could complicate things, however. |
|
|
3332 | |
|
|
3333 | The most portable way to handle signals is to block signals in all threads |
|
|
3334 | except the initial one, and run the default loop in the initial thread as |
|
|
3335 | well. |
|
|
3336 | |
|
|
3337 | =item C<long> must be large enough for common memory allocation sizes |
|
|
3338 | |
|
|
3339 | To improve portability and simplify using libev, libev uses C<long> |
|
|
3340 | internally instead of C<size_t> when allocating its data structures. On |
|
|
3341 | non-POSIX systems (Microsoft...) this might be unexpectedly low, but |
|
|
3342 | is still at least 31 bits everywhere, which is enough for hundreds of |
|
|
3343 | millions of watchers. |
|
|
3344 | |
|
|
3345 | =item C<double> must hold a time value in seconds with enough accuracy |
|
|
3346 | |
|
|
3347 | The type C<double> is used to represent timestamps. It is required to |
|
|
3348 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
|
|
3349 | enough for at least into the year 4000. This requirement is fulfilled by |
|
|
3350 | implementations implementing IEEE 754 (basically all existing ones). |
|
|
3351 | |
|
|
3352 | =back |
|
|
3353 | |
|
|
3354 | If you know of other additional requirements drop me a note. |
|
|
3355 | |
|
|
3356 | |
1697 | =head1 AUTHOR |
3357 | =head1 AUTHOR |
1698 | |
3358 | |
1699 | Marc Lehmann <libev@schmorp.de>. |
3359 | Marc Lehmann <libev@schmorp.de>. |
1700 | |
3360 | |