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3 | libev - a high performance full-featured event loop written in C |
3 | libev - a high performance full-featured event loop written in C |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
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8 | |
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9 | =head1 EXAMPLE PROGRAM |
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10 | |
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11 | #include <ev.h> |
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12 | |
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13 | ev_io stdin_watcher; |
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14 | ev_timer timeout_watcher; |
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15 | |
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16 | /* called when data readable on stdin */ |
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17 | static void |
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18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
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19 | { |
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20 | /* puts ("stdin ready"); */ |
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21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
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22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
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23 | } |
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24 | |
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25 | static void |
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26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
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27 | { |
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28 | /* puts ("timeout"); */ |
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29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
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30 | } |
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31 | |
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32 | int |
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33 | main (void) |
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34 | { |
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35 | struct ev_loop *loop = ev_default_loop (0); |
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36 | |
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37 | /* initialise an io watcher, then start it */ |
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38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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39 | ev_io_start (loop, &stdin_watcher); |
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40 | |
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41 | /* simple non-repeating 5.5 second timeout */ |
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42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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43 | ev_timer_start (loop, &timeout_watcher); |
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44 | |
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45 | /* loop till timeout or data ready */ |
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46 | ev_loop (loop, 0); |
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47 | |
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48 | return 0; |
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49 | } |
8 | |
50 | |
9 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
10 | |
52 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
53 | 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 |
54 | file descriptor being readable or a timeout occuring), and it will manage |
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21 | details of the event, and then hand it over to libev by I<starting> the |
63 | details of the event, and then hand it over to libev by I<starting> the |
22 | watcher. |
64 | watcher. |
23 | |
65 | |
24 | =head1 FEATURES |
66 | =head1 FEATURES |
25 | |
67 | |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
68 | Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
69 | bsd-specific C<kqueue> and the solaris-specific event port mechanisms |
28 | timers with customised rescheduling, signal events, process status change |
70 | for file descriptor events (C<ev_io>), relative timers (C<ev_timer>), |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
71 | absolute timers with customised rescheduling (C<ev_periodic>), synchronous |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
72 | signals (C<ev_signal>), process status change events (C<ev_child>), and |
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73 | event watchers dealing with the event loop mechanism itself (C<ev_idle>, |
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74 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
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75 | file watchers (C<ev_stat>) and even limited support for fork events |
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76 | (C<ev_fork>). |
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77 | |
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78 | It also is quite fast (see this |
31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
79 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
32 | it to libevent for example). |
80 | for example). |
33 | |
81 | |
34 | =head1 CONVENTIONS |
82 | =head1 CONVENTIONS |
35 | |
83 | |
36 | Libev is very configurable. In this manual the default configuration |
84 | Libev is very configurable. In this manual the default configuration will |
37 | will be described, which supports multiple event loops. For more info |
85 | be described, which supports multiple event loops. For more info about |
38 | about various configuration options please have a look at the file |
86 | various configuration options please have a look at B<EMBED> section in |
39 | F<README.embed> in the libev distribution. If libev was configured without |
87 | this manual. If libev was configured without support for multiple event |
40 | support for multiple event loops, then all functions taking an initial |
88 | loops, then all functions taking an initial argument of name C<loop> |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
89 | (which is always of type C<struct ev_loop *>) will not have this argument. |
42 | will not have this argument. |
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43 | |
90 | |
44 | =head1 TIME REPRESENTATION |
91 | =head1 TIME REPRESENTATION |
45 | |
92 | |
46 | Libev represents time as a single floating point number, representing the |
93 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
94 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
95 | 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 |
96 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
97 | to the C<double> type in C, and when you need to do any calculations on |
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98 | it, you should treat it as such. |
51 | |
99 | |
52 | =head1 GLOBAL FUNCTIONS |
100 | =head1 GLOBAL FUNCTIONS |
53 | |
101 | |
54 | These functions can be called anytime, even before initialising the |
102 | These functions can be called anytime, even before initialising the |
55 | library in any way. |
103 | library in any way. |
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75 | Usually, it's a good idea to terminate if the major versions mismatch, |
123 | Usually, it's a good idea to terminate if the major versions mismatch, |
76 | as this indicates an incompatible change. Minor versions are usually |
124 | as this indicates an incompatible change. Minor versions are usually |
77 | compatible to older versions, so a larger minor version alone is usually |
125 | compatible to older versions, so a larger minor version alone is usually |
78 | not a problem. |
126 | not a problem. |
79 | |
127 | |
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128 | Example: Make sure we haven't accidentally been linked against the wrong |
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129 | version. |
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130 | |
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131 | assert (("libev version mismatch", |
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132 | ev_version_major () == EV_VERSION_MAJOR |
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133 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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134 | |
80 | =item unsigned int ev_supported_backends () |
135 | =item unsigned int ev_supported_backends () |
81 | |
136 | |
82 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
137 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
83 | value) compiled into this binary of libev (independent of their |
138 | value) compiled into this binary of libev (independent of their |
84 | availability on the system you are running on). See C<ev_default_loop> for |
139 | availability on the system you are running on). See C<ev_default_loop> for |
85 | a description of the set values. |
140 | a description of the set values. |
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141 | |
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142 | Example: make sure we have the epoll method, because yeah this is cool and |
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143 | a must have and can we have a torrent of it please!!!11 |
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144 | |
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145 | assert (("sorry, no epoll, no sex", |
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146 | ev_supported_backends () & EVBACKEND_EPOLL)); |
86 | |
147 | |
87 | =item unsigned int ev_recommended_backends () |
148 | =item unsigned int ev_recommended_backends () |
88 | |
149 | |
89 | Return the set of all backends compiled into this binary of libev and also |
150 | Return the set of all backends compiled into this binary of libev and also |
90 | recommended for this platform. This set is often smaller than the one |
151 | recommended for this platform. This set is often smaller than the one |
91 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
152 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
92 | most BSDs and will not be autodetected unless you explicitly request it |
153 | most BSDs and will not be autodetected unless you explicitly request it |
93 | (assuming you know what you are doing). This is the set of backends that |
154 | (assuming you know what you are doing). This is the set of backends that |
94 | libev will probe for if you specify no backends explicitly. |
155 | libev will probe for if you specify no backends explicitly. |
95 | |
156 | |
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157 | =item unsigned int ev_embeddable_backends () |
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158 | |
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159 | Returns the set of backends that are embeddable in other event loops. This |
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160 | is the theoretical, all-platform, value. To find which backends |
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161 | might be supported on the current system, you would need to look at |
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162 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
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163 | recommended ones. |
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164 | |
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165 | See the description of C<ev_embed> watchers for more info. |
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166 | |
96 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
167 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
97 | |
168 | |
98 | Sets the allocation function to use (the prototype is similar to the |
169 | Sets the allocation function to use (the prototype and semantics are |
99 | realloc C function, the semantics are identical). It is used to allocate |
170 | identical to the realloc C function). It is used to allocate and free |
100 | and free memory (no surprises here). If it returns zero when memory |
171 | memory (no surprises here). If it returns zero when memory needs to be |
101 | needs to be allocated, the library might abort or take some potentially |
172 | allocated, the library might abort or take some potentially destructive |
102 | destructive action. The default is your system realloc function. |
173 | action. The default is your system realloc function. |
103 | |
174 | |
104 | You could override this function in high-availability programs to, say, |
175 | You could override this function in high-availability programs to, say, |
105 | free some memory if it cannot allocate memory, to use a special allocator, |
176 | free some memory if it cannot allocate memory, to use a special allocator, |
106 | or even to sleep a while and retry until some memory is available. |
177 | or even to sleep a while and retry until some memory is available. |
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178 | |
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179 | Example: Replace the libev allocator with one that waits a bit and then |
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180 | retries). |
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181 | |
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182 | static void * |
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183 | persistent_realloc (void *ptr, size_t size) |
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184 | { |
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185 | for (;;) |
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186 | { |
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187 | void *newptr = realloc (ptr, size); |
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188 | |
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189 | if (newptr) |
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190 | return newptr; |
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191 | |
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192 | sleep (60); |
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193 | } |
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194 | } |
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195 | |
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196 | ... |
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197 | ev_set_allocator (persistent_realloc); |
107 | |
198 | |
108 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
199 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
109 | |
200 | |
110 | Set the callback function to call on a retryable syscall error (such |
201 | Set the callback function to call on a retryable syscall error (such |
111 | as failed select, poll, epoll_wait). The message is a printable string |
202 | as failed select, poll, epoll_wait). The message is a printable string |
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113 | callback is set, then libev will expect it to remedy the sitution, no |
204 | callback is set, then libev will expect it to remedy the sitution, no |
114 | matter what, when it returns. That is, libev will generally retry the |
205 | matter what, when it returns. That is, libev will generally retry the |
115 | requested operation, or, if the condition doesn't go away, do bad stuff |
206 | requested operation, or, if the condition doesn't go away, do bad stuff |
116 | (such as abort). |
207 | (such as abort). |
117 | |
208 | |
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209 | Example: This is basically the same thing that libev does internally, too. |
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210 | |
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211 | static void |
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212 | fatal_error (const char *msg) |
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213 | { |
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214 | perror (msg); |
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215 | abort (); |
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216 | } |
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217 | |
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218 | ... |
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219 | ev_set_syserr_cb (fatal_error); |
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220 | |
118 | =back |
221 | =back |
119 | |
222 | |
120 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
223 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
121 | |
224 | |
122 | An event loop is described by a C<struct ev_loop *>. The library knows two |
225 | An event loop is described by a C<struct ev_loop *>. The library knows two |
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257 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
360 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
258 | always distinct from the default loop. Unlike the default loop, it cannot |
361 | always distinct from the default loop. Unlike the default loop, it cannot |
259 | handle signal and child watchers, and attempts to do so will be greeted by |
362 | handle signal and child watchers, and attempts to do so will be greeted by |
260 | undefined behaviour (or a failed assertion if assertions are enabled). |
363 | undefined behaviour (or a failed assertion if assertions are enabled). |
261 | |
364 | |
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365 | Example: Try to create a event loop that uses epoll and nothing else. |
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366 | |
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367 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
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368 | if (!epoller) |
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369 | fatal ("no epoll found here, maybe it hides under your chair"); |
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370 | |
262 | =item ev_default_destroy () |
371 | =item ev_default_destroy () |
263 | |
372 | |
264 | Destroys the default loop again (frees all memory and kernel state |
373 | Destroys the default loop again (frees all memory and kernel state |
265 | etc.). This stops all registered event watchers (by not touching them in |
374 | etc.). None of the active event watchers will be stopped in the normal |
266 | any way whatsoever, although you cannot rely on this :). |
375 | sense, so e.g. C<ev_is_active> might still return true. It is your |
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376 | responsibility to either stop all watchers cleanly yoursef I<before> |
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377 | calling this function, or cope with the fact afterwards (which is usually |
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378 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
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379 | for example). |
267 | |
380 | |
268 | =item ev_loop_destroy (loop) |
381 | =item ev_loop_destroy (loop) |
269 | |
382 | |
270 | Like C<ev_default_destroy>, but destroys an event loop created by an |
383 | Like C<ev_default_destroy>, but destroys an event loop created by an |
271 | earlier call to C<ev_loop_new>. |
384 | earlier call to C<ev_loop_new>. |
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303 | use. |
416 | use. |
304 | |
417 | |
305 | =item ev_tstamp ev_now (loop) |
418 | =item ev_tstamp ev_now (loop) |
306 | |
419 | |
307 | Returns the current "event loop time", which is the time the event loop |
420 | Returns the current "event loop time", which is the time the event loop |
308 | got events and started processing them. This timestamp does not change |
421 | received events and started processing them. This timestamp does not |
309 | as long as callbacks are being processed, and this is also the base time |
422 | change as long as callbacks are being processed, and this is also the base |
310 | used for relative timers. You can treat it as the timestamp of the event |
423 | time used for relative timers. You can treat it as the timestamp of the |
311 | occuring (or more correctly, the mainloop finding out about it). |
424 | event occuring (or more correctly, libev finding out about it). |
312 | |
425 | |
313 | =item ev_loop (loop, int flags) |
426 | =item ev_loop (loop, int flags) |
314 | |
427 | |
315 | Finally, this is it, the event handler. This function usually is called |
428 | Finally, this is it, the event handler. This function usually is called |
316 | after you initialised all your watchers and you want to start handling |
429 | after you initialised all your watchers and you want to start handling |
317 | events. |
430 | events. |
318 | |
431 | |
319 | If the flags argument is specified as C<0>, it will not return until |
432 | If the flags argument is specified as C<0>, it will not return until |
320 | either no event watchers are active anymore or C<ev_unloop> was called. |
433 | either no event watchers are active anymore or C<ev_unloop> was called. |
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434 | |
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435 | Please note that an explicit C<ev_unloop> is usually better than |
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436 | relying on all watchers to be stopped when deciding when a program has |
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437 | finished (especially in interactive programs), but having a program that |
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438 | automatically loops as long as it has to and no longer by virtue of |
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439 | relying on its watchers stopping correctly is a thing of beauty. |
321 | |
440 | |
322 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
441 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
323 | those events and any outstanding ones, but will not block your process in |
442 | those events and any outstanding ones, but will not block your process in |
324 | case there are no events and will return after one iteration of the loop. |
443 | case there are no events and will return after one iteration of the loop. |
325 | |
444 | |
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350 | Signals and child watchers are implemented as I/O watchers, and will |
469 | Signals and child watchers are implemented as I/O watchers, and will |
351 | be handled here by queueing them when their watcher gets executed. |
470 | be handled here by queueing them when their watcher gets executed. |
352 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
471 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
353 | were used, return, otherwise continue with step *. |
472 | were used, return, otherwise continue with step *. |
354 | |
473 | |
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474 | Example: Queue some jobs and then loop until no events are outsanding |
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475 | anymore. |
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476 | |
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477 | ... queue jobs here, make sure they register event watchers as long |
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478 | ... as they still have work to do (even an idle watcher will do..) |
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479 | ev_loop (my_loop, 0); |
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480 | ... jobs done. yeah! |
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481 | |
355 | =item ev_unloop (loop, how) |
482 | =item ev_unloop (loop, how) |
356 | |
483 | |
357 | Can be used to make a call to C<ev_loop> return early (but only after it |
484 | Can be used to make a call to C<ev_loop> return early (but only after it |
358 | has processed all outstanding events). The C<how> argument must be either |
485 | has processed all outstanding events). The C<how> argument must be either |
359 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
486 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
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372 | visible to the libev user and should not keep C<ev_loop> from exiting if |
499 | visible to the libev user and should not keep C<ev_loop> from exiting if |
373 | no event watchers registered by it are active. It is also an excellent |
500 | no event watchers registered by it are active. It is also an excellent |
374 | way to do this for generic recurring timers or from within third-party |
501 | way to do this for generic recurring timers or from within third-party |
375 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
502 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
376 | |
503 | |
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504 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
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505 | running when nothing else is active. |
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506 | |
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507 | struct ev_signal exitsig; |
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508 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
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509 | ev_signal_start (loop, &exitsig); |
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510 | evf_unref (loop); |
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511 | |
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512 | Example: For some weird reason, unregister the above signal handler again. |
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513 | |
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514 | ev_ref (loop); |
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515 | ev_signal_stop (loop, &exitsig); |
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516 | |
377 | =back |
517 | =back |
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518 | |
378 | |
519 | |
379 | =head1 ANATOMY OF A WATCHER |
520 | =head1 ANATOMY OF A WATCHER |
380 | |
521 | |
381 | A watcher is a structure that you create and register to record your |
522 | A watcher is a structure that you create and register to record your |
382 | interest in some event. For instance, if you want to wait for STDIN to |
523 | interest in some event. For instance, if you want to wait for STDIN to |
… | |
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415 | *) >>), and you can stop watching for events at any time by calling the |
556 | *) >>), and you can stop watching for events at any time by calling the |
416 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
557 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
417 | |
558 | |
418 | As long as your watcher is active (has been started but not stopped) you |
559 | As long as your watcher is active (has been started but not stopped) you |
419 | must not touch the values stored in it. Most specifically you must never |
560 | must not touch the values stored in it. Most specifically you must never |
420 | reinitialise it or call its set macro. |
561 | reinitialise it or call its C<set> macro. |
421 | |
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422 | You can check whether an event is active by calling the C<ev_is_active |
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423 | (watcher *)> macro. To see whether an event is outstanding (but the |
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424 | callback for it has not been called yet) you can use the C<ev_is_pending |
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425 | (watcher *)> macro. |
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426 | |
562 | |
427 | Each and every callback receives the event loop pointer as first, the |
563 | Each and every callback receives the event loop pointer as first, the |
428 | registered watcher structure as second, and a bitset of received events as |
564 | registered watcher structure as second, and a bitset of received events as |
429 | third argument. |
565 | third argument. |
430 | |
566 | |
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454 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
590 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
455 | |
591 | |
456 | =item C<EV_CHILD> |
592 | =item C<EV_CHILD> |
457 | |
593 | |
458 | The pid specified in the C<ev_child> watcher has received a status change. |
594 | The pid specified in the C<ev_child> watcher has received a status change. |
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595 | |
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596 | =item C<EV_STAT> |
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597 | |
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598 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
459 | |
599 | |
460 | =item C<EV_IDLE> |
600 | =item C<EV_IDLE> |
461 | |
601 | |
462 | The C<ev_idle> watcher has determined that you have nothing better to do. |
602 | The C<ev_idle> watcher has determined that you have nothing better to do. |
463 | |
603 | |
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471 | received events. Callbacks of both watcher types can start and stop as |
611 | received events. Callbacks of both watcher types can start and stop as |
472 | many watchers as they want, and all of them will be taken into account |
612 | many watchers as they want, and all of them will be taken into account |
473 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
613 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
474 | C<ev_loop> from blocking). |
614 | C<ev_loop> from blocking). |
475 | |
615 | |
|
|
616 | =item C<EV_EMBED> |
|
|
617 | |
|
|
618 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
|
|
619 | |
|
|
620 | =item C<EV_FORK> |
|
|
621 | |
|
|
622 | The event loop has been resumed in the child process after fork (see |
|
|
623 | C<ev_fork>). |
|
|
624 | |
476 | =item C<EV_ERROR> |
625 | =item C<EV_ERROR> |
477 | |
626 | |
478 | An unspecified error has occured, the watcher has been stopped. This might |
627 | An unspecified error has occured, the watcher has been stopped. This might |
479 | happen because the watcher could not be properly started because libev |
628 | happen because the watcher could not be properly started because libev |
480 | ran out of memory, a file descriptor was found to be closed or any other |
629 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
486 | your callbacks is well-written it can just attempt the operation and cope |
635 | your callbacks is well-written it can just attempt the operation and cope |
487 | with the error from read() or write(). This will not work in multithreaded |
636 | with the error from read() or write(). This will not work in multithreaded |
488 | programs, though, so beware. |
637 | programs, though, so beware. |
489 | |
638 | |
490 | =back |
639 | =back |
|
|
640 | |
|
|
641 | =head2 GENERIC WATCHER FUNCTIONS |
|
|
642 | |
|
|
643 | In the following description, C<TYPE> stands for the watcher type, |
|
|
644 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
|
|
645 | |
|
|
646 | =over 4 |
|
|
647 | |
|
|
648 | =item C<ev_init> (ev_TYPE *watcher, callback) |
|
|
649 | |
|
|
650 | This macro initialises the generic portion of a watcher. The contents |
|
|
651 | of the watcher object can be arbitrary (so C<malloc> will do). Only |
|
|
652 | the generic parts of the watcher are initialised, you I<need> to call |
|
|
653 | the type-specific C<ev_TYPE_set> macro afterwards to initialise the |
|
|
654 | type-specific parts. For each type there is also a C<ev_TYPE_init> macro |
|
|
655 | which rolls both calls into one. |
|
|
656 | |
|
|
657 | You can reinitialise a watcher at any time as long as it has been stopped |
|
|
658 | (or never started) and there are no pending events outstanding. |
|
|
659 | |
|
|
660 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
661 | int revents)>. |
|
|
662 | |
|
|
663 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
|
|
664 | |
|
|
665 | This macro initialises the type-specific parts of a watcher. You need to |
|
|
666 | call C<ev_init> at least once before you call this macro, but you can |
|
|
667 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
|
|
668 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
669 | difference to the C<ev_init> macro). |
|
|
670 | |
|
|
671 | Although some watcher types do not have type-specific arguments |
|
|
672 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
|
|
673 | |
|
|
674 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
|
|
675 | |
|
|
676 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
|
|
677 | calls into a single call. This is the most convinient method to initialise |
|
|
678 | a watcher. The same limitations apply, of course. |
|
|
679 | |
|
|
680 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
|
|
681 | |
|
|
682 | Starts (activates) the given watcher. Only active watchers will receive |
|
|
683 | events. If the watcher is already active nothing will happen. |
|
|
684 | |
|
|
685 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
|
|
686 | |
|
|
687 | Stops the given watcher again (if active) and clears the pending |
|
|
688 | status. It is possible that stopped watchers are pending (for example, |
|
|
689 | non-repeating timers are being stopped when they become pending), but |
|
|
690 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
|
|
691 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
692 | good idea to always call its C<ev_TYPE_stop> function. |
|
|
693 | |
|
|
694 | =item bool ev_is_active (ev_TYPE *watcher) |
|
|
695 | |
|
|
696 | Returns a true value iff the watcher is active (i.e. it has been started |
|
|
697 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
698 | it. |
|
|
699 | |
|
|
700 | =item bool ev_is_pending (ev_TYPE *watcher) |
|
|
701 | |
|
|
702 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
703 | events but its callback has not yet been invoked). As long as a watcher |
|
|
704 | is pending (but not active) you must not call an init function on it (but |
|
|
705 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
|
|
706 | libev (e.g. you cnanot C<free ()> it). |
|
|
707 | |
|
|
708 | =item callback ev_cb (ev_TYPE *watcher) |
|
|
709 | |
|
|
710 | Returns the callback currently set on the watcher. |
|
|
711 | |
|
|
712 | =item ev_cb_set (ev_TYPE *watcher, callback) |
|
|
713 | |
|
|
714 | Change the callback. You can change the callback at virtually any time |
|
|
715 | (modulo threads). |
|
|
716 | |
|
|
717 | =back |
|
|
718 | |
491 | |
719 | |
492 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
720 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
493 | |
721 | |
494 | Each watcher has, by default, a member C<void *data> that you can change |
722 | Each watcher has, by default, a member C<void *data> that you can change |
495 | and read at any time, libev will completely ignore it. This can be used |
723 | and read at any time, libev will completely ignore it. This can be used |
… | |
… | |
513 | { |
741 | { |
514 | struct my_io *w = (struct my_io *)w_; |
742 | struct my_io *w = (struct my_io *)w_; |
515 | ... |
743 | ... |
516 | } |
744 | } |
517 | |
745 | |
518 | More interesting and less C-conformant ways of catsing your callback type |
746 | More interesting and less C-conformant ways of casting your callback type |
519 | have been omitted.... |
747 | instead have been omitted. |
|
|
748 | |
|
|
749 | Another common scenario is having some data structure with multiple |
|
|
750 | watchers: |
|
|
751 | |
|
|
752 | struct my_biggy |
|
|
753 | { |
|
|
754 | int some_data; |
|
|
755 | ev_timer t1; |
|
|
756 | ev_timer t2; |
|
|
757 | } |
|
|
758 | |
|
|
759 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
760 | you need to use C<offsetof>: |
|
|
761 | |
|
|
762 | #include <stddef.h> |
|
|
763 | |
|
|
764 | static void |
|
|
765 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
766 | { |
|
|
767 | struct my_biggy big = (struct my_biggy * |
|
|
768 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
769 | } |
|
|
770 | |
|
|
771 | static void |
|
|
772 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
773 | { |
|
|
774 | struct my_biggy big = (struct my_biggy * |
|
|
775 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
776 | } |
520 | |
777 | |
521 | |
778 | |
522 | =head1 WATCHER TYPES |
779 | =head1 WATCHER TYPES |
523 | |
780 | |
524 | This section describes each watcher in detail, but will not repeat |
781 | This section describes each watcher in detail, but will not repeat |
525 | information given in the last section. |
782 | information given in the last section. Any initialisation/set macros, |
|
|
783 | functions and members specific to the watcher type are explained. |
526 | |
784 | |
|
|
785 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
786 | while the watcher is active, you can look at the member and expect some |
|
|
787 | sensible content, but you must not modify it (you can modify it while the |
|
|
788 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
789 | means you can expect it to have some sensible content while the watcher |
|
|
790 | is active, but you can also modify it. Modifying it may not do something |
|
|
791 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
792 | not crash or malfunction in any way. |
|
|
793 | |
|
|
794 | |
527 | =head2 C<ev_io> - is this file descriptor readable or writable |
795 | =head2 C<ev_io> - is this file descriptor readable or writable? |
528 | |
796 | |
529 | I/O watchers check whether a file descriptor is readable or writable |
797 | I/O watchers check whether a file descriptor is readable or writable |
530 | in each iteration of the event loop (This behaviour is called |
798 | in each iteration of the event loop, or, more precisely, when reading |
531 | level-triggering because you keep receiving events as long as the |
799 | would not block the process and writing would at least be able to write |
532 | condition persists. Remember you can stop the watcher if you don't want to |
800 | some data. This behaviour is called level-triggering because you keep |
533 | act on the event and neither want to receive future events). |
801 | receiving events as long as the condition persists. Remember you can stop |
|
|
802 | the watcher if you don't want to act on the event and neither want to |
|
|
803 | receive future events. |
534 | |
804 | |
535 | In general you can register as many read and/or write event watchers per |
805 | In general you can register as many read and/or write event watchers per |
536 | fd as you want (as long as you don't confuse yourself). Setting all file |
806 | fd as you want (as long as you don't confuse yourself). Setting all file |
537 | descriptors to non-blocking mode is also usually a good idea (but not |
807 | descriptors to non-blocking mode is also usually a good idea (but not |
538 | required if you know what you are doing). |
808 | required if you know what you are doing). |
539 | |
809 | |
540 | You have to be careful with dup'ed file descriptors, though. Some backends |
810 | You have to be careful with dup'ed file descriptors, though. Some backends |
541 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
811 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
542 | descriptors correctly if you register interest in two or more fds pointing |
812 | descriptors correctly if you register interest in two or more fds pointing |
543 | to the same underlying file/socket etc. description (that is, they share |
813 | to the same underlying file/socket/etc. description (that is, they share |
544 | the same underlying "file open"). |
814 | the same underlying "file open"). |
545 | |
815 | |
546 | If you must do this, then force the use of a known-to-be-good backend |
816 | If you must do this, then force the use of a known-to-be-good backend |
547 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
817 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
548 | C<EVBACKEND_POLL>). |
818 | C<EVBACKEND_POLL>). |
549 | |
819 | |
|
|
820 | Another thing you have to watch out for is that it is quite easy to |
|
|
821 | receive "spurious" readyness notifications, that is your callback might |
|
|
822 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
823 | because there is no data. Not only are some backends known to create a |
|
|
824 | lot of those (for example solaris ports), it is very easy to get into |
|
|
825 | this situation even with a relatively standard program structure. Thus |
|
|
826 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
827 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
828 | |
|
|
829 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
830 | play around with an Xlib connection), then you have to seperately re-test |
|
|
831 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
832 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
833 | its own, so its quite safe to use). |
|
|
834 | |
550 | =over 4 |
835 | =over 4 |
551 | |
836 | |
552 | =item ev_io_init (ev_io *, callback, int fd, int events) |
837 | =item ev_io_init (ev_io *, callback, int fd, int events) |
553 | |
838 | |
554 | =item ev_io_set (ev_io *, int fd, int events) |
839 | =item ev_io_set (ev_io *, int fd, int events) |
555 | |
840 | |
556 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
841 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
557 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
842 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
558 | EV_WRITE> to receive the given events. |
843 | C<EV_READ | EV_WRITE> to receive the given events. |
559 | |
844 | |
560 | Please note that most of the more scalable backend mechanisms (for example |
845 | =item int fd [read-only] |
561 | epoll and solaris ports) can result in spurious readyness notifications |
846 | |
562 | for file descriptors, so you practically need to use non-blocking I/O (and |
847 | The file descriptor being watched. |
563 | treat callback invocation as hint only), or retest separately with a safe |
848 | |
564 | interface before doing I/O (XLib can do this), or force the use of either |
849 | =item int events [read-only] |
565 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
850 | |
566 | problem. Also note that it is quite easy to have your callback invoked |
851 | The events being watched. |
567 | when the readyness condition is no longer valid even when employing |
|
|
568 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
569 | I/O unconditionally. |
|
|
570 | |
852 | |
571 | =back |
853 | =back |
572 | |
854 | |
|
|
855 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
|
|
856 | readable, but only once. Since it is likely line-buffered, you could |
|
|
857 | attempt to read a whole line in the callback. |
|
|
858 | |
|
|
859 | static void |
|
|
860 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
861 | { |
|
|
862 | ev_io_stop (loop, w); |
|
|
863 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
864 | } |
|
|
865 | |
|
|
866 | ... |
|
|
867 | struct ev_loop *loop = ev_default_init (0); |
|
|
868 | struct ev_io stdin_readable; |
|
|
869 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
870 | ev_io_start (loop, &stdin_readable); |
|
|
871 | ev_loop (loop, 0); |
|
|
872 | |
|
|
873 | |
573 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
874 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
574 | |
875 | |
575 | Timer watchers are simple relative timers that generate an event after a |
876 | Timer watchers are simple relative timers that generate an event after a |
576 | given time, and optionally repeating in regular intervals after that. |
877 | given time, and optionally repeating in regular intervals after that. |
577 | |
878 | |
578 | The timers are based on real time, that is, if you register an event that |
879 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
619 | |
920 | |
620 | If the timer is repeating, either start it if necessary (with the repeat |
921 | If the timer is repeating, either start it if necessary (with the repeat |
621 | value), or reset the running timer to the repeat value. |
922 | value), or reset the running timer to the repeat value. |
622 | |
923 | |
623 | This sounds a bit complicated, but here is a useful and typical |
924 | This sounds a bit complicated, but here is a useful and typical |
624 | example: Imagine you have a tcp connection and you want a so-called idle |
925 | example: Imagine you have a tcp connection and you want a so-called |
625 | timeout, that is, you want to be called when there have been, say, 60 |
926 | idle timeout, that is, you want to be called when there have been, |
626 | seconds of inactivity on the socket. The easiest way to do this is to |
927 | say, 60 seconds of inactivity on the socket. The easiest way to do |
627 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
928 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
628 | time you successfully read or write some data. If you go into an idle |
929 | C<ev_timer_again> each time you successfully read or write some data. If |
629 | state where you do not expect data to travel on the socket, you can stop |
930 | you go into an idle state where you do not expect data to travel on the |
630 | the timer, and again will automatically restart it if need be. |
931 | socket, you can stop the timer, and again will automatically restart it if |
|
|
932 | need be. |
|
|
933 | |
|
|
934 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
|
|
935 | and only ever use the C<repeat> value: |
|
|
936 | |
|
|
937 | ev_timer_init (timer, callback, 0., 5.); |
|
|
938 | ev_timer_again (loop, timer); |
|
|
939 | ... |
|
|
940 | timer->again = 17.; |
|
|
941 | ev_timer_again (loop, timer); |
|
|
942 | ... |
|
|
943 | timer->again = 10.; |
|
|
944 | ev_timer_again (loop, timer); |
|
|
945 | |
|
|
946 | This is more efficient then stopping/starting the timer eahc time you want |
|
|
947 | to modify its timeout value. |
|
|
948 | |
|
|
949 | =item ev_tstamp repeat [read-write] |
|
|
950 | |
|
|
951 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
952 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
953 | which is also when any modifications are taken into account. |
631 | |
954 | |
632 | =back |
955 | =back |
633 | |
956 | |
|
|
957 | Example: Create a timer that fires after 60 seconds. |
|
|
958 | |
|
|
959 | static void |
|
|
960 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
961 | { |
|
|
962 | .. one minute over, w is actually stopped right here |
|
|
963 | } |
|
|
964 | |
|
|
965 | struct ev_timer mytimer; |
|
|
966 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
967 | ev_timer_start (loop, &mytimer); |
|
|
968 | |
|
|
969 | Example: Create a timeout timer that times out after 10 seconds of |
|
|
970 | inactivity. |
|
|
971 | |
|
|
972 | static void |
|
|
973 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
974 | { |
|
|
975 | .. ten seconds without any activity |
|
|
976 | } |
|
|
977 | |
|
|
978 | struct ev_timer mytimer; |
|
|
979 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
980 | ev_timer_again (&mytimer); /* start timer */ |
|
|
981 | ev_loop (loop, 0); |
|
|
982 | |
|
|
983 | // and in some piece of code that gets executed on any "activity": |
|
|
984 | // reset the timeout to start ticking again at 10 seconds |
|
|
985 | ev_timer_again (&mytimer); |
|
|
986 | |
|
|
987 | |
634 | =head2 C<ev_periodic> - to cron or not to cron |
988 | =head2 C<ev_periodic> - to cron or not to cron? |
635 | |
989 | |
636 | Periodic watchers are also timers of a kind, but they are very versatile |
990 | Periodic watchers are also timers of a kind, but they are very versatile |
637 | (and unfortunately a bit complex). |
991 | (and unfortunately a bit complex). |
638 | |
992 | |
639 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
993 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
640 | but on wallclock time (absolute time). You can tell a periodic watcher |
994 | but on wallclock time (absolute time). You can tell a periodic watcher |
641 | to trigger "at" some specific point in time. For example, if you tell a |
995 | to trigger "at" some specific point in time. For example, if you tell a |
642 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
996 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
643 | + 10.>) and then reset your system clock to the last year, then it will |
997 | + 10.>) and then reset your system clock to the last year, then it will |
644 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
998 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
645 | roughly 10 seconds later and of course not if you reset your system time |
999 | roughly 10 seconds later and of course not if you reset your system time |
646 | again). |
1000 | again). |
647 | |
1001 | |
… | |
… | |
731 | Simply stops and restarts the periodic watcher again. This is only useful |
1085 | Simply stops and restarts the periodic watcher again. This is only useful |
732 | when you changed some parameters or the reschedule callback would return |
1086 | when you changed some parameters or the reschedule callback would return |
733 | a different time than the last time it was called (e.g. in a crond like |
1087 | a different time than the last time it was called (e.g. in a crond like |
734 | program when the crontabs have changed). |
1088 | program when the crontabs have changed). |
735 | |
1089 | |
|
|
1090 | =item ev_tstamp interval [read-write] |
|
|
1091 | |
|
|
1092 | The current interval value. Can be modified any time, but changes only |
|
|
1093 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1094 | called. |
|
|
1095 | |
|
|
1096 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1097 | |
|
|
1098 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1099 | switched off. Can be changed any time, but changes only take effect when |
|
|
1100 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1101 | |
736 | =back |
1102 | =back |
737 | |
1103 | |
|
|
1104 | Example: Call a callback every hour, or, more precisely, whenever the |
|
|
1105 | system clock is divisible by 3600. The callback invocation times have |
|
|
1106 | potentially a lot of jittering, but good long-term stability. |
|
|
1107 | |
|
|
1108 | static void |
|
|
1109 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1110 | { |
|
|
1111 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
1112 | } |
|
|
1113 | |
|
|
1114 | struct ev_periodic hourly_tick; |
|
|
1115 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
1116 | ev_periodic_start (loop, &hourly_tick); |
|
|
1117 | |
|
|
1118 | Example: The same as above, but use a reschedule callback to do it: |
|
|
1119 | |
|
|
1120 | #include <math.h> |
|
|
1121 | |
|
|
1122 | static ev_tstamp |
|
|
1123 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1124 | { |
|
|
1125 | return fmod (now, 3600.) + 3600.; |
|
|
1126 | } |
|
|
1127 | |
|
|
1128 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1129 | |
|
|
1130 | Example: Call a callback every hour, starting now: |
|
|
1131 | |
|
|
1132 | struct ev_periodic hourly_tick; |
|
|
1133 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1134 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1135 | ev_periodic_start (loop, &hourly_tick); |
|
|
1136 | |
|
|
1137 | |
738 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1138 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
739 | |
1139 | |
740 | Signal watchers will trigger an event when the process receives a specific |
1140 | Signal watchers will trigger an event when the process receives a specific |
741 | signal one or more times. Even though signals are very asynchronous, libev |
1141 | signal one or more times. Even though signals are very asynchronous, libev |
742 | will try it's best to deliver signals synchronously, i.e. as part of the |
1142 | will try it's best to deliver signals synchronously, i.e. as part of the |
743 | normal event processing, like any other event. |
1143 | normal event processing, like any other event. |
… | |
… | |
756 | =item ev_signal_set (ev_signal *, int signum) |
1156 | =item ev_signal_set (ev_signal *, int signum) |
757 | |
1157 | |
758 | Configures the watcher to trigger on the given signal number (usually one |
1158 | Configures the watcher to trigger on the given signal number (usually one |
759 | of the C<SIGxxx> constants). |
1159 | of the C<SIGxxx> constants). |
760 | |
1160 | |
|
|
1161 | =item int signum [read-only] |
|
|
1162 | |
|
|
1163 | The signal the watcher watches out for. |
|
|
1164 | |
761 | =back |
1165 | =back |
762 | |
1166 | |
|
|
1167 | |
763 | =head2 C<ev_child> - wait for pid status changes |
1168 | =head2 C<ev_child> - watch out for process status changes |
764 | |
1169 | |
765 | Child watchers trigger when your process receives a SIGCHLD in response to |
1170 | Child watchers trigger when your process receives a SIGCHLD in response to |
766 | some child status changes (most typically when a child of yours dies). |
1171 | some child status changes (most typically when a child of yours dies). |
767 | |
1172 | |
768 | =over 4 |
1173 | =over 4 |
… | |
… | |
776 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1181 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
777 | the status word (use the macros from C<sys/wait.h> and see your systems |
1182 | the status word (use the macros from C<sys/wait.h> and see your systems |
778 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1183 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
779 | process causing the status change. |
1184 | process causing the status change. |
780 | |
1185 | |
|
|
1186 | =item int pid [read-only] |
|
|
1187 | |
|
|
1188 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1189 | |
|
|
1190 | =item int rpid [read-write] |
|
|
1191 | |
|
|
1192 | The process id that detected a status change. |
|
|
1193 | |
|
|
1194 | =item int rstatus [read-write] |
|
|
1195 | |
|
|
1196 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1197 | C<waitpid> and C<sys/wait.h> documentation for details). |
|
|
1198 | |
781 | =back |
1199 | =back |
782 | |
1200 | |
|
|
1201 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1202 | |
|
|
1203 | static void |
|
|
1204 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1205 | { |
|
|
1206 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1207 | } |
|
|
1208 | |
|
|
1209 | struct ev_signal signal_watcher; |
|
|
1210 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1211 | ev_signal_start (loop, &sigint_cb); |
|
|
1212 | |
|
|
1213 | |
|
|
1214 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1215 | |
|
|
1216 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1217 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1218 | compared to the last time, invoking the callback if it did. |
|
|
1219 | |
|
|
1220 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1221 | not exist" is a status change like any other. The condition "path does |
|
|
1222 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1223 | otherwise always forced to be at least one) and all the other fields of |
|
|
1224 | the stat buffer having unspecified contents. |
|
|
1225 | |
|
|
1226 | Since there is no standard to do this, the portable implementation simply |
|
|
1227 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
|
|
1228 | can specify a recommended polling interval for this case. If you specify |
|
|
1229 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1230 | unspecified default> value will be used (which you can expect to be around |
|
|
1231 | five seconds, although this might change dynamically). Libev will also |
|
|
1232 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1233 | usually overkill. |
|
|
1234 | |
|
|
1235 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1236 | as even with OS-supported change notifications, this can be |
|
|
1237 | resource-intensive. |
|
|
1238 | |
|
|
1239 | At the time of this writing, no specific OS backends are implemented, but |
|
|
1240 | if demand increases, at least a kqueue and inotify backend will be added. |
|
|
1241 | |
|
|
1242 | =over 4 |
|
|
1243 | |
|
|
1244 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1245 | |
|
|
1246 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1247 | |
|
|
1248 | Configures the watcher to wait for status changes of the given |
|
|
1249 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1250 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1251 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1252 | path for as long as the watcher is active. |
|
|
1253 | |
|
|
1254 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1255 | relative to the attributes at the time the watcher was started (or the |
|
|
1256 | last change was detected). |
|
|
1257 | |
|
|
1258 | =item ev_stat_stat (ev_stat *) |
|
|
1259 | |
|
|
1260 | Updates the stat buffer immediately with new values. If you change the |
|
|
1261 | watched path in your callback, you could call this fucntion to avoid |
|
|
1262 | detecting this change (while introducing a race condition). Can also be |
|
|
1263 | useful simply to find out the new values. |
|
|
1264 | |
|
|
1265 | =item ev_statdata attr [read-only] |
|
|
1266 | |
|
|
1267 | The most-recently detected attributes of the file. Although the type is of |
|
|
1268 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1269 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1270 | was some error while C<stat>ing the file. |
|
|
1271 | |
|
|
1272 | =item ev_statdata prev [read-only] |
|
|
1273 | |
|
|
1274 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1275 | C<prev> != C<attr>. |
|
|
1276 | |
|
|
1277 | =item ev_tstamp interval [read-only] |
|
|
1278 | |
|
|
1279 | The specified interval. |
|
|
1280 | |
|
|
1281 | =item const char *path [read-only] |
|
|
1282 | |
|
|
1283 | The filesystem path that is being watched. |
|
|
1284 | |
|
|
1285 | =back |
|
|
1286 | |
|
|
1287 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1288 | |
|
|
1289 | static void |
|
|
1290 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1291 | { |
|
|
1292 | /* /etc/passwd changed in some way */ |
|
|
1293 | if (w->attr.st_nlink) |
|
|
1294 | { |
|
|
1295 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1296 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1297 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1298 | } |
|
|
1299 | else |
|
|
1300 | /* you shalt not abuse printf for puts */ |
|
|
1301 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1302 | "if this is windows, they already arrived\n"); |
|
|
1303 | } |
|
|
1304 | |
|
|
1305 | ... |
|
|
1306 | ev_stat passwd; |
|
|
1307 | |
|
|
1308 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1309 | ev_stat_start (loop, &passwd); |
|
|
1310 | |
|
|
1311 | |
783 | =head2 C<ev_idle> - when you've got nothing better to do |
1312 | =head2 C<ev_idle> - when you've got nothing better to do... |
784 | |
1313 | |
785 | Idle watchers trigger events when there are no other events are pending |
1314 | Idle watchers trigger events when there are no other events are pending |
786 | (prepare, check and other idle watchers do not count). That is, as long |
1315 | (prepare, check and other idle watchers do not count). That is, as long |
787 | as your process is busy handling sockets or timeouts (or even signals, |
1316 | as your process is busy handling sockets or timeouts (or even signals, |
788 | imagine) it will not be triggered. But when your process is idle all idle |
1317 | imagine) it will not be triggered. But when your process is idle all idle |
… | |
… | |
806 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1335 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
807 | believe me. |
1336 | believe me. |
808 | |
1337 | |
809 | =back |
1338 | =back |
810 | |
1339 | |
|
|
1340 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
|
|
1341 | callback, free it. Also, use no error checking, as usual. |
|
|
1342 | |
|
|
1343 | static void |
|
|
1344 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1345 | { |
|
|
1346 | free (w); |
|
|
1347 | // now do something you wanted to do when the program has |
|
|
1348 | // no longer asnything immediate to do. |
|
|
1349 | } |
|
|
1350 | |
|
|
1351 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1352 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1353 | ev_idle_start (loop, idle_cb); |
|
|
1354 | |
|
|
1355 | |
811 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1356 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
812 | |
1357 | |
813 | Prepare and check watchers are usually (but not always) used in tandem: |
1358 | Prepare and check watchers are usually (but not always) used in tandem: |
814 | prepare watchers get invoked before the process blocks and check watchers |
1359 | prepare watchers get invoked before the process blocks and check watchers |
815 | afterwards. |
1360 | afterwards. |
816 | |
1361 | |
|
|
1362 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1363 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1364 | watchers. Other loops than the current one are fine, however. The |
|
|
1365 | rationale behind this is that you do not need to check for recursion in |
|
|
1366 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1367 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1368 | called in pairs bracketing the blocking call. |
|
|
1369 | |
817 | Their main purpose is to integrate other event mechanisms into libev. This |
1370 | Their main purpose is to integrate other event mechanisms into libev and |
818 | could be used, for example, to track variable changes, implement your own |
1371 | their use is somewhat advanced. This could be used, for example, to track |
819 | watchers, integrate net-snmp or a coroutine library and lots more. |
1372 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1373 | coroutine library and lots more. They are also occasionally useful if |
|
|
1374 | you cache some data and want to flush it before blocking (for example, |
|
|
1375 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1376 | watcher). |
820 | |
1377 | |
821 | This is done by examining in each prepare call which file descriptors need |
1378 | This is done by examining in each prepare call which file descriptors need |
822 | to be watched by the other library, registering C<ev_io> watchers for |
1379 | to be watched by the other library, registering C<ev_io> watchers for |
823 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1380 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
824 | provide just this functionality). Then, in the check watcher you check for |
1381 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
846 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1403 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
847 | macros, but using them is utterly, utterly and completely pointless. |
1404 | macros, but using them is utterly, utterly and completely pointless. |
848 | |
1405 | |
849 | =back |
1406 | =back |
850 | |
1407 | |
|
|
1408 | Example: To include a library such as adns, you would add IO watchers |
|
|
1409 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1410 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1411 | pseudo-code only of course: |
|
|
1412 | |
|
|
1413 | static ev_io iow [nfd]; |
|
|
1414 | static ev_timer tw; |
|
|
1415 | |
|
|
1416 | static void |
|
|
1417 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1418 | { |
|
|
1419 | // set the relevant poll flags |
|
|
1420 | // could also call adns_processreadable etc. here |
|
|
1421 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1422 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1423 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1424 | } |
|
|
1425 | |
|
|
1426 | // create io watchers for each fd and a timer before blocking |
|
|
1427 | static void |
|
|
1428 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1429 | { |
|
|
1430 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1431 | // actual code will need to loop here and realloc etc. |
|
|
1432 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1433 | |
|
|
1434 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1435 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1436 | ev_timer_start (loop, &tw); |
|
|
1437 | |
|
|
1438 | // create on ev_io per pollfd |
|
|
1439 | for (int i = 0; i < nfd; ++i) |
|
|
1440 | { |
|
|
1441 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1442 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1443 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1444 | |
|
|
1445 | fds [i].revents = 0; |
|
|
1446 | iow [i].data = fds + i; |
|
|
1447 | ev_io_start (loop, iow + i); |
|
|
1448 | } |
|
|
1449 | } |
|
|
1450 | |
|
|
1451 | // stop all watchers after blocking |
|
|
1452 | static void |
|
|
1453 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1454 | { |
|
|
1455 | ev_timer_stop (loop, &tw); |
|
|
1456 | |
|
|
1457 | for (int i = 0; i < nfd; ++i) |
|
|
1458 | ev_io_stop (loop, iow + i); |
|
|
1459 | |
|
|
1460 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1461 | } |
|
|
1462 | |
|
|
1463 | |
|
|
1464 | =head2 C<ev_embed> - when one backend isn't enough... |
|
|
1465 | |
|
|
1466 | This is a rather advanced watcher type that lets you embed one event loop |
|
|
1467 | into another (currently only C<ev_io> events are supported in the embedded |
|
|
1468 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1469 | fashion and must not be used). |
|
|
1470 | |
|
|
1471 | There are primarily two reasons you would want that: work around bugs and |
|
|
1472 | prioritise I/O. |
|
|
1473 | |
|
|
1474 | As an example for a bug workaround, the kqueue backend might only support |
|
|
1475 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1476 | still want to make use of it because you have many sockets and it scales |
|
|
1477 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1478 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1479 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1480 | at least you can use both at what they are best. |
|
|
1481 | |
|
|
1482 | As for prioritising I/O: rarely you have the case where some fds have |
|
|
1483 | to be watched and handled very quickly (with low latency), and even |
|
|
1484 | priorities and idle watchers might have too much overhead. In this case |
|
|
1485 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1486 | a second one, and embed the second one in the first. |
|
|
1487 | |
|
|
1488 | As long as the watcher is active, the callback will be invoked every time |
|
|
1489 | there might be events pending in the embedded loop. The callback must then |
|
|
1490 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
|
|
1491 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1492 | loop strictly lower priority for example). You can also set the callback |
|
|
1493 | to C<0>, in which case the embed watcher will automatically execute the |
|
|
1494 | embedded loop sweep. |
|
|
1495 | |
|
|
1496 | As long as the watcher is started it will automatically handle events. The |
|
|
1497 | callback will be invoked whenever some events have been handled. You can |
|
|
1498 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
1499 | interested in that. |
|
|
1500 | |
|
|
1501 | Also, there have not currently been made special provisions for forking: |
|
|
1502 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
|
|
1503 | but you will also have to stop and restart any C<ev_embed> watchers |
|
|
1504 | yourself. |
|
|
1505 | |
|
|
1506 | Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1507 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
|
|
1508 | portable one. |
|
|
1509 | |
|
|
1510 | So when you want to use this feature you will always have to be prepared |
|
|
1511 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1512 | this is to have a separate variables for your embeddable loop, try to |
|
|
1513 | create it, and if that fails, use the normal loop for everything: |
|
|
1514 | |
|
|
1515 | struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1516 | struct ev_loop *loop_lo = 0; |
|
|
1517 | struct ev_embed embed; |
|
|
1518 | |
|
|
1519 | // see if there is a chance of getting one that works |
|
|
1520 | // (remember that a flags value of 0 means autodetection) |
|
|
1521 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1522 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1523 | : 0; |
|
|
1524 | |
|
|
1525 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1526 | if (loop_lo) |
|
|
1527 | { |
|
|
1528 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1529 | ev_embed_start (loop_hi, &embed); |
|
|
1530 | } |
|
|
1531 | else |
|
|
1532 | loop_lo = loop_hi; |
|
|
1533 | |
|
|
1534 | =over 4 |
|
|
1535 | |
|
|
1536 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1537 | |
|
|
1538 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1539 | |
|
|
1540 | Configures the watcher to embed the given loop, which must be |
|
|
1541 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1542 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1543 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1544 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1545 | |
|
|
1546 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1547 | |
|
|
1548 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1549 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1550 | apropriate way for embedded loops. |
|
|
1551 | |
|
|
1552 | =item struct ev_loop *loop [read-only] |
|
|
1553 | |
|
|
1554 | The embedded event loop. |
|
|
1555 | |
|
|
1556 | =back |
|
|
1557 | |
|
|
1558 | |
|
|
1559 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
1560 | |
|
|
1561 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
1562 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1563 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
1564 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
1565 | and only in the child after the fork. If whoever good citizen calling |
|
|
1566 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
1567 | handlers will be invoked, too, of course. |
|
|
1568 | |
|
|
1569 | =over 4 |
|
|
1570 | |
|
|
1571 | =item ev_fork_init (ev_signal *, callback) |
|
|
1572 | |
|
|
1573 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
1574 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
1575 | believe me. |
|
|
1576 | |
|
|
1577 | =back |
|
|
1578 | |
|
|
1579 | |
851 | =head1 OTHER FUNCTIONS |
1580 | =head1 OTHER FUNCTIONS |
852 | |
1581 | |
853 | There are some other functions of possible interest. Described. Here. Now. |
1582 | There are some other functions of possible interest. Described. Here. Now. |
854 | |
1583 | |
855 | =over 4 |
1584 | =over 4 |
… | |
… | |
884 | /* stdin might have data for us, joy! */; |
1613 | /* stdin might have data for us, joy! */; |
885 | } |
1614 | } |
886 | |
1615 | |
887 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1616 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
888 | |
1617 | |
889 | =item ev_feed_event (loop, watcher, int events) |
1618 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
890 | |
1619 | |
891 | Feeds the given event set into the event loop, as if the specified event |
1620 | Feeds the given event set into the event loop, as if the specified event |
892 | had happened for the specified watcher (which must be a pointer to an |
1621 | had happened for the specified watcher (which must be a pointer to an |
893 | initialised but not necessarily started event watcher). |
1622 | initialised but not necessarily started event watcher). |
894 | |
1623 | |
895 | =item ev_feed_fd_event (loop, int fd, int revents) |
1624 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
896 | |
1625 | |
897 | Feed an event on the given fd, as if a file descriptor backend detected |
1626 | Feed an event on the given fd, as if a file descriptor backend detected |
898 | the given events it. |
1627 | the given events it. |
899 | |
1628 | |
900 | =item ev_feed_signal_event (loop, int signum) |
1629 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
901 | |
1630 | |
902 | Feed an event as if the given signal occured (loop must be the default loop!). |
1631 | Feed an event as if the given signal occured (C<loop> must be the default |
|
|
1632 | loop!). |
903 | |
1633 | |
904 | =back |
1634 | =back |
|
|
1635 | |
905 | |
1636 | |
906 | =head1 LIBEVENT EMULATION |
1637 | =head1 LIBEVENT EMULATION |
907 | |
1638 | |
908 | Libev offers a compatibility emulation layer for libevent. It cannot |
1639 | Libev offers a compatibility emulation layer for libevent. It cannot |
909 | emulate the internals of libevent, so here are some usage hints: |
1640 | emulate the internals of libevent, so here are some usage hints: |
… | |
… | |
930 | |
1661 | |
931 | =back |
1662 | =back |
932 | |
1663 | |
933 | =head1 C++ SUPPORT |
1664 | =head1 C++ SUPPORT |
934 | |
1665 | |
935 | TBD. |
1666 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1667 | you to use some convinience methods to start/stop watchers and also change |
|
|
1668 | the callback model to a model using method callbacks on objects. |
|
|
1669 | |
|
|
1670 | To use it, |
|
|
1671 | |
|
|
1672 | #include <ev++.h> |
|
|
1673 | |
|
|
1674 | (it is not installed by default). This automatically includes F<ev.h> |
|
|
1675 | and puts all of its definitions (many of them macros) into the global |
|
|
1676 | namespace. All C++ specific things are put into the C<ev> namespace. |
|
|
1677 | |
|
|
1678 | It should support all the same embedding options as F<ev.h>, most notably |
|
|
1679 | C<EV_MULTIPLICITY>. |
|
|
1680 | |
|
|
1681 | Here is a list of things available in the C<ev> namespace: |
|
|
1682 | |
|
|
1683 | =over 4 |
|
|
1684 | |
|
|
1685 | =item C<ev::READ>, C<ev::WRITE> etc. |
|
|
1686 | |
|
|
1687 | These are just enum values with the same values as the C<EV_READ> etc. |
|
|
1688 | macros from F<ev.h>. |
|
|
1689 | |
|
|
1690 | =item C<ev::tstamp>, C<ev::now> |
|
|
1691 | |
|
|
1692 | Aliases to the same types/functions as with the C<ev_> prefix. |
|
|
1693 | |
|
|
1694 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
|
|
1695 | |
|
|
1696 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
|
|
1697 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
|
|
1698 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
|
|
1699 | defines by many implementations. |
|
|
1700 | |
|
|
1701 | All of those classes have these methods: |
|
|
1702 | |
|
|
1703 | =over 4 |
|
|
1704 | |
|
|
1705 | =item ev::TYPE::TYPE (object *, object::method *) |
|
|
1706 | |
|
|
1707 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
|
|
1708 | |
|
|
1709 | =item ev::TYPE::~TYPE |
|
|
1710 | |
|
|
1711 | The constructor takes a pointer to an object and a method pointer to |
|
|
1712 | the event handler callback to call in this class. The constructor calls |
|
|
1713 | C<ev_init> for you, which means you have to call the C<set> method |
|
|
1714 | before starting it. If you do not specify a loop then the constructor |
|
|
1715 | automatically associates the default loop with this watcher. |
|
|
1716 | |
|
|
1717 | The destructor automatically stops the watcher if it is active. |
|
|
1718 | |
|
|
1719 | =item w->set (struct ev_loop *) |
|
|
1720 | |
|
|
1721 | Associates a different C<struct ev_loop> with this watcher. You can only |
|
|
1722 | do this when the watcher is inactive (and not pending either). |
|
|
1723 | |
|
|
1724 | =item w->set ([args]) |
|
|
1725 | |
|
|
1726 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
|
|
1727 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1728 | automatically stopped and restarted. |
|
|
1729 | |
|
|
1730 | =item w->start () |
|
|
1731 | |
|
|
1732 | Starts the watcher. Note that there is no C<loop> argument as the |
|
|
1733 | constructor already takes the loop. |
|
|
1734 | |
|
|
1735 | =item w->stop () |
|
|
1736 | |
|
|
1737 | Stops the watcher if it is active. Again, no C<loop> argument. |
|
|
1738 | |
|
|
1739 | =item w->again () C<ev::timer>, C<ev::periodic> only |
|
|
1740 | |
|
|
1741 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
|
|
1742 | C<ev_TYPE_again> function. |
|
|
1743 | |
|
|
1744 | =item w->sweep () C<ev::embed> only |
|
|
1745 | |
|
|
1746 | Invokes C<ev_embed_sweep>. |
|
|
1747 | |
|
|
1748 | =item w->update () C<ev::stat> only |
|
|
1749 | |
|
|
1750 | Invokes C<ev_stat_stat>. |
|
|
1751 | |
|
|
1752 | =back |
|
|
1753 | |
|
|
1754 | =back |
|
|
1755 | |
|
|
1756 | Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1757 | the constructor. |
|
|
1758 | |
|
|
1759 | class myclass |
|
|
1760 | { |
|
|
1761 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1762 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1763 | |
|
|
1764 | myclass (); |
|
|
1765 | } |
|
|
1766 | |
|
|
1767 | myclass::myclass (int fd) |
|
|
1768 | : io (this, &myclass::io_cb), |
|
|
1769 | idle (this, &myclass::idle_cb) |
|
|
1770 | { |
|
|
1771 | io.start (fd, ev::READ); |
|
|
1772 | } |
|
|
1773 | |
|
|
1774 | |
|
|
1775 | =head1 MACRO MAGIC |
|
|
1776 | |
|
|
1777 | Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1778 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
|
|
1779 | callbacks have an initial C<struct ev_loop *> argument. |
|
|
1780 | |
|
|
1781 | To make it easier to write programs that cope with either variant, the |
|
|
1782 | following macros are defined: |
|
|
1783 | |
|
|
1784 | =over 4 |
|
|
1785 | |
|
|
1786 | =item C<EV_A>, C<EV_A_> |
|
|
1787 | |
|
|
1788 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
1789 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
1790 | C<EV_A_> is used when other arguments are following. Example: |
|
|
1791 | |
|
|
1792 | ev_unref (EV_A); |
|
|
1793 | ev_timer_add (EV_A_ watcher); |
|
|
1794 | ev_loop (EV_A_ 0); |
|
|
1795 | |
|
|
1796 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
1797 | which is often provided by the following macro. |
|
|
1798 | |
|
|
1799 | =item C<EV_P>, C<EV_P_> |
|
|
1800 | |
|
|
1801 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
1802 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
1803 | C<EV_P_> is used when other parameters are following. Example: |
|
|
1804 | |
|
|
1805 | // this is how ev_unref is being declared |
|
|
1806 | static void ev_unref (EV_P); |
|
|
1807 | |
|
|
1808 | // this is how you can declare your typical callback |
|
|
1809 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1810 | |
|
|
1811 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
1812 | suitable for use with C<EV_A>. |
|
|
1813 | |
|
|
1814 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
1815 | |
|
|
1816 | Similar to the other two macros, this gives you the value of the default |
|
|
1817 | loop, if multiple loops are supported ("ev loop default"). |
|
|
1818 | |
|
|
1819 | =back |
|
|
1820 | |
|
|
1821 | Example: Declare and initialise a check watcher, working regardless of |
|
|
1822 | wether multiple loops are supported or not. |
|
|
1823 | |
|
|
1824 | static void |
|
|
1825 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1826 | { |
|
|
1827 | ev_check_stop (EV_A_ w); |
|
|
1828 | } |
|
|
1829 | |
|
|
1830 | ev_check check; |
|
|
1831 | ev_check_init (&check, check_cb); |
|
|
1832 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1833 | ev_loop (EV_DEFAULT_ 0); |
|
|
1834 | |
|
|
1835 | |
|
|
1836 | =head1 EMBEDDING |
|
|
1837 | |
|
|
1838 | Libev can (and often is) directly embedded into host |
|
|
1839 | applications. Examples of applications that embed it include the Deliantra |
|
|
1840 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1841 | and rxvt-unicode. |
|
|
1842 | |
|
|
1843 | The goal is to enable you to just copy the neecssary files into your |
|
|
1844 | source directory without having to change even a single line in them, so |
|
|
1845 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1846 | libev somewhere in your source tree). |
|
|
1847 | |
|
|
1848 | =head2 FILESETS |
|
|
1849 | |
|
|
1850 | Depending on what features you need you need to include one or more sets of files |
|
|
1851 | in your app. |
|
|
1852 | |
|
|
1853 | =head3 CORE EVENT LOOP |
|
|
1854 | |
|
|
1855 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
1856 | configuration (no autoconf): |
|
|
1857 | |
|
|
1858 | #define EV_STANDALONE 1 |
|
|
1859 | #include "ev.c" |
|
|
1860 | |
|
|
1861 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
1862 | single C source file only to provide the function implementations. To use |
|
|
1863 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
1864 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
1865 | where you can put other configuration options): |
|
|
1866 | |
|
|
1867 | #define EV_STANDALONE 1 |
|
|
1868 | #include "ev.h" |
|
|
1869 | |
|
|
1870 | Both header files and implementation files can be compiled with a C++ |
|
|
1871 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1872 | as a bug). |
|
|
1873 | |
|
|
1874 | You need the following files in your source tree, or in a directory |
|
|
1875 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
1876 | |
|
|
1877 | ev.h |
|
|
1878 | ev.c |
|
|
1879 | ev_vars.h |
|
|
1880 | ev_wrap.h |
|
|
1881 | |
|
|
1882 | ev_win32.c required on win32 platforms only |
|
|
1883 | |
|
|
1884 | ev_select.c only when select backend is enabled (which is by default) |
|
|
1885 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1886 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1887 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1888 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1889 | |
|
|
1890 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
1891 | to compile this single file. |
|
|
1892 | |
|
|
1893 | =head3 LIBEVENT COMPATIBILITY API |
|
|
1894 | |
|
|
1895 | To include the libevent compatibility API, also include: |
|
|
1896 | |
|
|
1897 | #include "event.c" |
|
|
1898 | |
|
|
1899 | in the file including F<ev.c>, and: |
|
|
1900 | |
|
|
1901 | #include "event.h" |
|
|
1902 | |
|
|
1903 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
1904 | |
|
|
1905 | You need the following additional files for this: |
|
|
1906 | |
|
|
1907 | event.h |
|
|
1908 | event.c |
|
|
1909 | |
|
|
1910 | =head3 AUTOCONF SUPPORT |
|
|
1911 | |
|
|
1912 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
1913 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
1914 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
|
|
1915 | include F<config.h> and configure itself accordingly. |
|
|
1916 | |
|
|
1917 | For this of course you need the m4 file: |
|
|
1918 | |
|
|
1919 | libev.m4 |
|
|
1920 | |
|
|
1921 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
1922 | |
|
|
1923 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1924 | before including any of its files. The default is not to build for multiplicity |
|
|
1925 | and only include the select backend. |
|
|
1926 | |
|
|
1927 | =over 4 |
|
|
1928 | |
|
|
1929 | =item EV_STANDALONE |
|
|
1930 | |
|
|
1931 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
1932 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
1933 | implementations for some libevent functions (such as logging, which is not |
|
|
1934 | supported). It will also not define any of the structs usually found in |
|
|
1935 | F<event.h> that are not directly supported by the libev core alone. |
|
|
1936 | |
|
|
1937 | =item EV_USE_MONOTONIC |
|
|
1938 | |
|
|
1939 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1940 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1941 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1942 | usually have to link against librt or something similar. Enabling it when |
|
|
1943 | the functionality isn't available is safe, though, althoguh you have |
|
|
1944 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
1945 | function is hiding in (often F<-lrt>). |
|
|
1946 | |
|
|
1947 | =item EV_USE_REALTIME |
|
|
1948 | |
|
|
1949 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1950 | realtime clock option at compiletime (and assume its availability at |
|
|
1951 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1952 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
1953 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
|
|
1954 | in the description of C<EV_USE_MONOTONIC>, though. |
|
|
1955 | |
|
|
1956 | =item EV_USE_SELECT |
|
|
1957 | |
|
|
1958 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
1959 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
1960 | other method takes over, select will be it. Otherwise the select backend |
|
|
1961 | will not be compiled in. |
|
|
1962 | |
|
|
1963 | =item EV_SELECT_USE_FD_SET |
|
|
1964 | |
|
|
1965 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
1966 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1967 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
1968 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1969 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1970 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
1971 | influence the size of the C<fd_set> used. |
|
|
1972 | |
|
|
1973 | =item EV_SELECT_IS_WINSOCKET |
|
|
1974 | |
|
|
1975 | When defined to C<1>, the select backend will assume that |
|
|
1976 | select/socket/connect etc. don't understand file descriptors but |
|
|
1977 | wants osf handles on win32 (this is the case when the select to |
|
|
1978 | be used is the winsock select). This means that it will call |
|
|
1979 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
1980 | it is assumed that all these functions actually work on fds, even |
|
|
1981 | on win32. Should not be defined on non-win32 platforms. |
|
|
1982 | |
|
|
1983 | =item EV_USE_POLL |
|
|
1984 | |
|
|
1985 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
1986 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1987 | takes precedence over select. |
|
|
1988 | |
|
|
1989 | =item EV_USE_EPOLL |
|
|
1990 | |
|
|
1991 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
1992 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
1993 | otherwise another method will be used as fallback. This is the |
|
|
1994 | preferred backend for GNU/Linux systems. |
|
|
1995 | |
|
|
1996 | =item EV_USE_KQUEUE |
|
|
1997 | |
|
|
1998 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
1999 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
2000 | otherwise another method will be used as fallback. This is the preferred |
|
|
2001 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
2002 | supports some types of fds correctly (the only platform we found that |
|
|
2003 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
2004 | not be used unless explicitly requested. The best way to use it is to find |
|
|
2005 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
2006 | kqueue loop. |
|
|
2007 | |
|
|
2008 | =item EV_USE_PORT |
|
|
2009 | |
|
|
2010 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
2011 | 10 port style backend. Its availability will be detected at runtime, |
|
|
2012 | otherwise another method will be used as fallback. This is the preferred |
|
|
2013 | backend for Solaris 10 systems. |
|
|
2014 | |
|
|
2015 | =item EV_USE_DEVPOLL |
|
|
2016 | |
|
|
2017 | reserved for future expansion, works like the USE symbols above. |
|
|
2018 | |
|
|
2019 | =item EV_H |
|
|
2020 | |
|
|
2021 | The name of the F<ev.h> header file used to include it. The default if |
|
|
2022 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
|
|
2023 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
2024 | |
|
|
2025 | =item EV_CONFIG_H |
|
|
2026 | |
|
|
2027 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
2028 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
2029 | C<EV_H>, above. |
|
|
2030 | |
|
|
2031 | =item EV_EVENT_H |
|
|
2032 | |
|
|
2033 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
2034 | of how the F<event.h> header can be found. |
|
|
2035 | |
|
|
2036 | =item EV_PROTOTYPES |
|
|
2037 | |
|
|
2038 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
2039 | prototypes, but still define all the structs and other symbols. This is |
|
|
2040 | occasionally useful if you want to provide your own wrapper functions |
|
|
2041 | around libev functions. |
|
|
2042 | |
|
|
2043 | =item EV_MULTIPLICITY |
|
|
2044 | |
|
|
2045 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
2046 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
2047 | additional independent event loops. Otherwise there will be no support |
|
|
2048 | for multiple event loops and there is no first event loop pointer |
|
|
2049 | argument. Instead, all functions act on the single default loop. |
|
|
2050 | |
|
|
2051 | =item EV_PERIODIC_ENABLE |
|
|
2052 | |
|
|
2053 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2054 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2055 | code. |
|
|
2056 | |
|
|
2057 | =item EV_EMBED_ENABLE |
|
|
2058 | |
|
|
2059 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2060 | defined to be C<0>, then they are not. |
|
|
2061 | |
|
|
2062 | =item EV_STAT_ENABLE |
|
|
2063 | |
|
|
2064 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2065 | defined to be C<0>, then they are not. |
|
|
2066 | |
|
|
2067 | =item EV_FORK_ENABLE |
|
|
2068 | |
|
|
2069 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2070 | defined to be C<0>, then they are not. |
|
|
2071 | |
|
|
2072 | =item EV_MINIMAL |
|
|
2073 | |
|
|
2074 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2075 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
2076 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2077 | |
|
|
2078 | =item EV_PID_HASHSIZE |
|
|
2079 | |
|
|
2080 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2081 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2082 | than enough. If you need to manage thousands of children you might want to |
|
|
2083 | increase this value. |
|
|
2084 | |
|
|
2085 | =item EV_COMMON |
|
|
2086 | |
|
|
2087 | By default, all watchers have a C<void *data> member. By redefining |
|
|
2088 | this macro to a something else you can include more and other types of |
|
|
2089 | members. You have to define it each time you include one of the files, |
|
|
2090 | though, and it must be identical each time. |
|
|
2091 | |
|
|
2092 | For example, the perl EV module uses something like this: |
|
|
2093 | |
|
|
2094 | #define EV_COMMON \ |
|
|
2095 | SV *self; /* contains this struct */ \ |
|
|
2096 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2097 | |
|
|
2098 | =item EV_CB_DECLARE (type) |
|
|
2099 | |
|
|
2100 | =item EV_CB_INVOKE (watcher, revents) |
|
|
2101 | |
|
|
2102 | =item ev_set_cb (ev, cb) |
|
|
2103 | |
|
|
2104 | Can be used to change the callback member declaration in each watcher, |
|
|
2105 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2106 | definition and a statement, respectively. See the F<ev.v> header file for |
|
|
2107 | their default definitions. One possible use for overriding these is to |
|
|
2108 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
|
|
2109 | method calls instead of plain function calls in C++. |
|
|
2110 | |
|
|
2111 | =head2 EXAMPLES |
|
|
2112 | |
|
|
2113 | For a real-world example of a program the includes libev |
|
|
2114 | verbatim, you can have a look at the EV perl module |
|
|
2115 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
2116 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
2117 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
2118 | will be compiled. It is pretty complex because it provides its own header |
|
|
2119 | file. |
|
|
2120 | |
|
|
2121 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
2122 | that everybody includes and which overrides some autoconf choices: |
|
|
2123 | |
|
|
2124 | #define EV_USE_POLL 0 |
|
|
2125 | #define EV_MULTIPLICITY 0 |
|
|
2126 | #define EV_PERIODICS 0 |
|
|
2127 | #define EV_CONFIG_H <config.h> |
|
|
2128 | |
|
|
2129 | #include "ev++.h" |
|
|
2130 | |
|
|
2131 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
2132 | |
|
|
2133 | #include "ev_cpp.h" |
|
|
2134 | #include "ev.c" |
|
|
2135 | |
|
|
2136 | |
|
|
2137 | =head1 COMPLEXITIES |
|
|
2138 | |
|
|
2139 | In this section the complexities of (many of) the algorithms used inside |
|
|
2140 | libev will be explained. For complexity discussions about backends see the |
|
|
2141 | documentation for C<ev_default_init>. |
|
|
2142 | |
|
|
2143 | =over 4 |
|
|
2144 | |
|
|
2145 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
2146 | |
|
|
2147 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
2148 | |
|
|
2149 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
2150 | |
|
|
2151 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
2152 | |
|
|
2153 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
|
|
2154 | |
|
|
2155 | =item Finding the next timer per loop iteration: O(1) |
|
|
2156 | |
|
|
2157 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
2158 | |
|
|
2159 | =item Activating one watcher: O(1) |
|
|
2160 | |
|
|
2161 | =back |
|
|
2162 | |
936 | |
2163 | |
937 | =head1 AUTHOR |
2164 | =head1 AUTHOR |
938 | |
2165 | |
939 | Marc Lehmann <libev@schmorp.de>. |
2166 | Marc Lehmann <libev@schmorp.de>. |
940 | |
2167 | |