… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
|
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9 | =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 | } |
|
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50 | |
9 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
10 | |
52 | |
|
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53 | The newest version of this document is also available as a html-formatted |
|
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54 | web page you might find easier to navigate when reading it for the first |
|
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55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
|
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56 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
57 | 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 |
58 | file descriptor being readable or a timeout occurring), and it will manage |
13 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
14 | |
60 | |
15 | To do this, it must take more or less complete control over your process |
61 | To do this, it must take more or less complete control over your process |
16 | (or thread) by executing the I<event loop> handler, and will then |
62 | (or thread) by executing the I<event loop> handler, and will then |
17 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
… | |
… | |
21 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
22 | watcher. |
68 | watcher. |
23 | |
69 | |
24 | =head1 FEATURES |
70 | =head1 FEATURES |
25 | |
71 | |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
28 | timers with customised rescheduling, signal events, process status change |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
76 | with customised rescheduling (C<ev_periodic>), synchronous signals |
|
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77 | (C<ev_signal>), process status change events (C<ev_child>), and event |
|
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78 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
|
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79 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
|
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80 | file watchers (C<ev_stat>) and even limited support for fork events |
|
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81 | (C<ev_fork>). |
|
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82 | |
|
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83 | It also is quite fast (see this |
31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
32 | it to libevent for example). |
85 | for example). |
33 | |
86 | |
34 | =head1 CONVENTIONS |
87 | =head1 CONVENTIONS |
35 | |
88 | |
36 | Libev is very configurable. In this manual the default configuration |
89 | Libev is very configurable. In this manual the default configuration will |
37 | will be described, which supports multiple event loops. For more info |
90 | be described, which supports multiple event loops. For more info about |
38 | about various configuration options please have a look at the file |
91 | 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 |
92 | this manual. If libev was configured without support for multiple event |
40 | support for multiple event loops, then all functions taking an initial |
93 | 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 *>) |
94 | (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 | |
95 | |
44 | =head1 TIME REPRESENTATION |
96 | =head1 TIME REPRESENTATION |
45 | |
97 | |
46 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | 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 |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
102 | to the C<double> type in C, and when you need to do any calculations on |
|
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103 | it, you should treat it as some floatingpoint value. Unlike the name |
|
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104 | component C<stamp> might indicate, it is also used for time differences |
|
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105 | throughout libev. |
51 | |
106 | |
52 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
53 | |
108 | |
54 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
55 | library in any way. |
110 | library in any way. |
… | |
… | |
60 | |
115 | |
61 | Returns the current time as libev would use it. Please note that the |
116 | Returns the current time as libev would use it. Please note that the |
62 | C<ev_now> function is usually faster and also often returns the timestamp |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
63 | you actually want to know. |
118 | you actually want to know. |
64 | |
119 | |
|
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120 | =item ev_sleep (ev_tstamp interval) |
|
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121 | |
|
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122 | Sleep for the given interval: The current thread will be blocked until |
|
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123 | either it is interrupted or the given time interval has passed. Basically |
|
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124 | this is a subsecond-resolution C<sleep ()>. |
|
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125 | |
65 | =item int ev_version_major () |
126 | =item int ev_version_major () |
66 | |
127 | |
67 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
68 | |
129 | |
69 | You can find out the major and minor version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
70 | you linked against by calling the functions C<ev_version_major> and |
131 | you linked against by calling the functions C<ev_version_major> and |
71 | C<ev_version_minor>. If you want, you can compare against the global |
132 | C<ev_version_minor>. If you want, you can compare against the global |
72 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
133 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
73 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
74 | |
135 | |
|
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136 | These version numbers refer to the ABI version of the library, not the |
|
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137 | release version. |
|
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138 | |
75 | Usually, it's a good idea to terminate if the major versions mismatch, |
139 | Usually, it's a good idea to terminate if the major versions mismatch, |
76 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
77 | compatible to older versions, so a larger minor version alone is usually |
141 | compatible to older versions, so a larger minor version alone is usually |
78 | not a problem. |
142 | not a problem. |
79 | |
143 | |
|
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144 | Example: Make sure we haven't accidentally been linked against the wrong |
|
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145 | version. |
|
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146 | |
|
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147 | assert (("libev version mismatch", |
|
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148 | ev_version_major () == EV_VERSION_MAJOR |
|
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149 | && ev_version_minor () >= EV_VERSION_MINOR)); |
|
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150 | |
|
|
151 | =item unsigned int ev_supported_backends () |
|
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152 | |
|
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153 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
|
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154 | value) compiled into this binary of libev (independent of their |
|
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155 | availability on the system you are running on). See C<ev_default_loop> for |
|
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156 | a description of the set values. |
|
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157 | |
|
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158 | Example: make sure we have the epoll method, because yeah this is cool and |
|
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159 | a must have and can we have a torrent of it please!!!11 |
|
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160 | |
|
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161 | assert (("sorry, no epoll, no sex", |
|
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162 | ev_supported_backends () & EVBACKEND_EPOLL)); |
|
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163 | |
|
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164 | =item unsigned int ev_recommended_backends () |
|
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165 | |
|
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166 | Return the set of all backends compiled into this binary of libev and also |
|
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167 | recommended for this platform. This set is often smaller than the one |
|
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168 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
|
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169 | most BSDs and will not be autodetected unless you explicitly request it |
|
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170 | (assuming you know what you are doing). This is the set of backends that |
|
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171 | libev will probe for if you specify no backends explicitly. |
|
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172 | |
|
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173 | =item unsigned int ev_embeddable_backends () |
|
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174 | |
|
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175 | Returns the set of backends that are embeddable in other event loops. This |
|
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176 | is the theoretical, all-platform, value. To find which backends |
|
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177 | might be supported on the current system, you would need to look at |
|
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178 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
|
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179 | recommended ones. |
|
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180 | |
|
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181 | See the description of C<ev_embed> watchers for more info. |
|
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182 | |
80 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
183 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
81 | |
184 | |
82 | Sets the allocation function to use (the prototype is similar to the |
185 | Sets the allocation function to use (the prototype is similar - the |
83 | realloc C function, the semantics are identical). It is used to allocate |
186 | semantics is identical - to the realloc C function). It is used to |
84 | and free memory (no surprises here). If it returns zero when memory |
187 | allocate and free memory (no surprises here). If it returns zero when |
85 | needs to be allocated, the library might abort or take some potentially |
188 | memory needs to be allocated, the library might abort or take some |
86 | destructive action. The default is your system realloc function. |
189 | potentially destructive action. The default is your system realloc |
|
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190 | function. |
87 | |
191 | |
88 | You could override this function in high-availability programs to, say, |
192 | You could override this function in high-availability programs to, say, |
89 | free some memory if it cannot allocate memory, to use a special allocator, |
193 | free some memory if it cannot allocate memory, to use a special allocator, |
90 | or even to sleep a while and retry until some memory is available. |
194 | or even to sleep a while and retry until some memory is available. |
|
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195 | |
|
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196 | Example: Replace the libev allocator with one that waits a bit and then |
|
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197 | retries). |
|
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198 | |
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199 | static void * |
|
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200 | persistent_realloc (void *ptr, size_t size) |
|
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201 | { |
|
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202 | for (;;) |
|
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203 | { |
|
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204 | void *newptr = realloc (ptr, size); |
|
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205 | |
|
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206 | if (newptr) |
|
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207 | return newptr; |
|
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208 | |
|
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209 | sleep (60); |
|
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210 | } |
|
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211 | } |
|
|
212 | |
|
|
213 | ... |
|
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214 | ev_set_allocator (persistent_realloc); |
91 | |
215 | |
92 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
216 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
93 | |
217 | |
94 | Set the callback function to call on a retryable syscall error (such |
218 | Set the callback function to call on a retryable syscall error (such |
95 | as failed select, poll, epoll_wait). The message is a printable string |
219 | as failed select, poll, epoll_wait). The message is a printable string |
… | |
… | |
97 | callback is set, then libev will expect it to remedy the sitution, no |
221 | callback is set, then libev will expect it to remedy the sitution, no |
98 | matter what, when it returns. That is, libev will generally retry the |
222 | matter what, when it returns. That is, libev will generally retry the |
99 | requested operation, or, if the condition doesn't go away, do bad stuff |
223 | requested operation, or, if the condition doesn't go away, do bad stuff |
100 | (such as abort). |
224 | (such as abort). |
101 | |
225 | |
|
|
226 | Example: This is basically the same thing that libev does internally, too. |
|
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227 | |
|
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228 | static void |
|
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229 | fatal_error (const char *msg) |
|
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230 | { |
|
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231 | perror (msg); |
|
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232 | abort (); |
|
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233 | } |
|
|
234 | |
|
|
235 | ... |
|
|
236 | ev_set_syserr_cb (fatal_error); |
|
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237 | |
102 | =back |
238 | =back |
103 | |
239 | |
104 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
240 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
105 | |
241 | |
106 | An event loop is described by a C<struct ev_loop *>. The library knows two |
242 | An event loop is described by a C<struct ev_loop *>. The library knows two |
… | |
… | |
119 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
255 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
120 | |
256 | |
121 | This will initialise the default event loop if it hasn't been initialised |
257 | This will initialise the default event loop if it hasn't been initialised |
122 | yet and return it. If the default loop could not be initialised, returns |
258 | yet and return it. If the default loop could not be initialised, returns |
123 | false. If it already was initialised it simply returns it (and ignores the |
259 | false. If it already was initialised it simply returns it (and ignores the |
124 | flags). |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
125 | |
261 | |
126 | If you don't know what event loop to use, use the one returned from this |
262 | If you don't know what event loop to use, use the one returned from this |
127 | function. |
263 | function. |
128 | |
264 | |
129 | The flags argument can be used to specify special behaviour or specific |
265 | The flags argument can be used to specify special behaviour or specific |
130 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO). |
266 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
131 | |
267 | |
132 | It supports the following flags: |
268 | The following flags are supported: |
133 | |
269 | |
134 | =over 4 |
270 | =over 4 |
135 | |
271 | |
136 | =item C<EVFLAG_AUTO> |
272 | =item C<EVFLAG_AUTO> |
137 | |
273 | |
… | |
… | |
145 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
281 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
146 | override the flags completely if it is found in the environment. This is |
282 | override the flags completely if it is found in the environment. This is |
147 | useful to try out specific backends to test their performance, or to work |
283 | useful to try out specific backends to test their performance, or to work |
148 | around bugs. |
284 | around bugs. |
149 | |
285 | |
|
|
286 | =item C<EVFLAG_FORKCHECK> |
|
|
287 | |
|
|
288 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
289 | a fork, you can also make libev check for a fork in each iteration by |
|
|
290 | enabling this flag. |
|
|
291 | |
|
|
292 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
293 | and thus this might slow down your event loop if you do a lot of loop |
|
|
294 | iterations and little real work, but is usually not noticeable (on my |
|
|
295 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
296 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
297 | C<pthread_atfork> which is even faster). |
|
|
298 | |
|
|
299 | The big advantage of this flag is that you can forget about fork (and |
|
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300 | forget about forgetting to tell libev about forking) when you use this |
|
|
301 | flag. |
|
|
302 | |
|
|
303 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
304 | environment variable. |
|
|
305 | |
150 | =item C<EVMETHOD_SELECT> (value 1, portable select backend) |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
151 | |
307 | |
152 | This is your standard select(2) backend. Not I<completely> standard, as |
308 | This is your standard select(2) backend. Not I<completely> standard, as |
153 | libev tries to roll its own fd_set with no limits on the number of fds, |
309 | libev tries to roll its own fd_set with no limits on the number of fds, |
154 | but if that fails, expect a fairly low limit on the number of fds when |
310 | but if that fails, expect a fairly low limit on the number of fds when |
155 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
311 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
156 | the fastest backend for a low number of fds. |
312 | the fastest backend for a low number of fds. |
157 | |
313 | |
158 | =item C<EVMETHOD_POLL> (value 2, poll backend, available everywhere except on windows) |
314 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
159 | |
315 | |
160 | And this is your standard poll(2) backend. It's more complicated than |
316 | And this is your standard poll(2) backend. It's more complicated than |
161 | select, but handles sparse fds better and has no artificial limit on the |
317 | select, but handles sparse fds better and has no artificial limit on the |
162 | number of fds you can use (except it will slow down considerably with a |
318 | number of fds you can use (except it will slow down considerably with a |
163 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
319 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
164 | |
320 | |
165 | =item C<EVMETHOD_EPOLL> (value 4, Linux) |
321 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
166 | |
322 | |
167 | For few fds, this backend is a bit little slower than poll and select, |
323 | For few fds, this backend is a bit little slower than poll and select, |
168 | but it scales phenomenally better. While poll and select usually scale like |
324 | but it scales phenomenally better. While poll and select usually scale |
169 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
325 | like O(total_fds) where n is the total number of fds (or the highest fd), |
170 | either O(1) or O(active_fds). |
326 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
|
|
327 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
|
328 | cases and rewiring a syscall per fd change, no fork support and bad |
|
|
329 | support for dup: |
171 | |
330 | |
172 | While stopping and starting an I/O watcher in the same iteration will |
331 | While stopping, setting and starting an I/O watcher in the same iteration |
173 | result in some caching, there is still a syscall per such incident |
332 | will result in some caching, there is still a syscall per such incident |
174 | (because the fd could point to a different file description now), so its |
333 | (because the fd could point to a different file description now), so its |
175 | best to avoid that. Also, dup()ed file descriptors might not work very |
334 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
176 | well if you register events for both fds. |
335 | very well if you register events for both fds. |
177 | |
336 | |
|
|
337 | Please note that epoll sometimes generates spurious notifications, so you |
|
|
338 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
|
339 | (or space) is available. |
|
|
340 | |
178 | =item C<EVMETHOD_KQUEUE> (value 8, most BSD clones) |
341 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
179 | |
342 | |
180 | Kqueue deserves special mention, as at the time of this writing, it |
343 | Kqueue deserves special mention, as at the time of this writing, it |
181 | was broken on all BSDs except NetBSD (usually it doesn't work with |
344 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
182 | anything but sockets and pipes, except on Darwin, where of course its |
345 | with anything but sockets and pipes, except on Darwin, where of course |
183 | completely useless). For this reason its not being "autodetected" unless |
346 | it's completely useless). For this reason it's not being "autodetected" |
184 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO). |
347 | unless you explicitly specify it explicitly in the flags (i.e. using |
|
|
348 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
|
349 | system like NetBSD. |
|
|
350 | |
|
|
351 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
352 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
353 | the target platform). See C<ev_embed> watchers for more info. |
185 | |
354 | |
186 | It scales in the same way as the epoll backend, but the interface to the |
355 | It scales in the same way as the epoll backend, but the interface to the |
187 | kernel is more efficient (which says nothing about its actual speed, of |
356 | kernel is more efficient (which says nothing about its actual speed, of |
188 | course). While starting and stopping an I/O watcher does not cause an |
357 | course). While stopping, setting and starting an I/O watcher does never |
189 | extra syscall as with epoll, it still adds up to four event changes per |
358 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
190 | incident, so its best to avoid that. |
359 | two event changes per incident, support for C<fork ()> is very bad and it |
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360 | drops fds silently in similarly hard-to-detect cases. |
191 | |
361 | |
192 | =item C<EVMETHOD_DEVPOLL> (value 16, Solaris 8) |
362 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
193 | |
363 | |
194 | This is not implemented yet (and might never be). |
364 | This is not implemented yet (and might never be). |
195 | |
365 | |
196 | =item C<EVMETHOD_PORT> (value 32, Solaris 10) |
366 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
197 | |
367 | |
198 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
368 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
199 | it's really slow, but it still scales very well (O(active_fds)). |
369 | it's really slow, but it still scales very well (O(active_fds)). |
200 | |
370 | |
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371 | Please note that solaris event ports can deliver a lot of spurious |
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372 | notifications, so you need to use non-blocking I/O or other means to avoid |
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373 | blocking when no data (or space) is available. |
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374 | |
201 | =item C<EVMETHOD_ALL> |
375 | =item C<EVBACKEND_ALL> |
202 | |
376 | |
203 | Try all backends (even potentially broken ones that wouldn't be tried |
377 | Try all backends (even potentially broken ones that wouldn't be tried |
204 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
378 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
205 | C<EVMETHOD_ALL & ~EVMETHOD_KQUEUE>. |
379 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
206 | |
380 | |
207 | =back |
381 | =back |
208 | |
382 | |
209 | If one or more of these are ored into the flags value, then only these |
383 | If one or more of these are ored into the flags value, then only these |
210 | backends will be tried (in the reverse order as given here). If none are |
384 | backends will be tried (in the reverse order as given here). If none are |
211 | specified, most compiled-in backend will be tried, usually in reverse |
385 | specified, most compiled-in backend will be tried, usually in reverse |
212 | order of their flag values :) |
386 | order of their flag values :) |
213 | |
387 | |
|
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388 | The most typical usage is like this: |
|
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389 | |
|
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390 | if (!ev_default_loop (0)) |
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391 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
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392 | |
|
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393 | Restrict libev to the select and poll backends, and do not allow |
|
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394 | environment settings to be taken into account: |
|
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395 | |
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396 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
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397 | |
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398 | Use whatever libev has to offer, but make sure that kqueue is used if |
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399 | available (warning, breaks stuff, best use only with your own private |
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400 | event loop and only if you know the OS supports your types of fds): |
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401 | |
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402 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
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403 | |
214 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
404 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
215 | |
405 | |
216 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
406 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
217 | always distinct from the default loop. Unlike the default loop, it cannot |
407 | always distinct from the default loop. Unlike the default loop, it cannot |
218 | handle signal and child watchers, and attempts to do so will be greeted by |
408 | handle signal and child watchers, and attempts to do so will be greeted by |
219 | undefined behaviour (or a failed assertion if assertions are enabled). |
409 | undefined behaviour (or a failed assertion if assertions are enabled). |
220 | |
410 | |
|
|
411 | Example: Try to create a event loop that uses epoll and nothing else. |
|
|
412 | |
|
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413 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
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414 | if (!epoller) |
|
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415 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
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416 | |
221 | =item ev_default_destroy () |
417 | =item ev_default_destroy () |
222 | |
418 | |
223 | Destroys the default loop again (frees all memory and kernel state |
419 | Destroys the default loop again (frees all memory and kernel state |
224 | etc.). This stops all registered event watchers (by not touching them in |
420 | etc.). None of the active event watchers will be stopped in the normal |
225 | any way whatsoever, although you cannot rely on this :). |
421 | sense, so e.g. C<ev_is_active> might still return true. It is your |
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422 | responsibility to either stop all watchers cleanly yoursef I<before> |
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423 | calling this function, or cope with the fact afterwards (which is usually |
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424 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
|
|
425 | for example). |
|
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426 | |
|
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427 | Note that certain global state, such as signal state, will not be freed by |
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428 | this function, and related watchers (such as signal and child watchers) |
|
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429 | would need to be stopped manually. |
|
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430 | |
|
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431 | In general it is not advisable to call this function except in the |
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432 | rare occasion where you really need to free e.g. the signal handling |
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433 | pipe fds. If you need dynamically allocated loops it is better to use |
|
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434 | C<ev_loop_new> and C<ev_loop_destroy>). |
226 | |
435 | |
227 | =item ev_loop_destroy (loop) |
436 | =item ev_loop_destroy (loop) |
228 | |
437 | |
229 | Like C<ev_default_destroy>, but destroys an event loop created by an |
438 | Like C<ev_default_destroy>, but destroys an event loop created by an |
230 | earlier call to C<ev_loop_new>. |
439 | earlier call to C<ev_loop_new>. |
… | |
… | |
234 | This function reinitialises the kernel state for backends that have |
443 | This function reinitialises the kernel state for backends that have |
235 | one. Despite the name, you can call it anytime, but it makes most sense |
444 | one. Despite the name, you can call it anytime, but it makes most sense |
236 | after forking, in either the parent or child process (or both, but that |
445 | after forking, in either the parent or child process (or both, but that |
237 | again makes little sense). |
446 | again makes little sense). |
238 | |
447 | |
239 | You I<must> call this function after forking if and only if you want to |
448 | You I<must> call this function in the child process after forking if and |
240 | use the event library in both processes. If you just fork+exec, you don't |
449 | only if you want to use the event library in both processes. If you just |
241 | have to call it. |
450 | fork+exec, you don't have to call it. |
242 | |
451 | |
243 | The function itself is quite fast and it's usually not a problem to call |
452 | The function itself is quite fast and it's usually not a problem to call |
244 | it just in case after a fork. To make this easy, the function will fit in |
453 | it just in case after a fork. To make this easy, the function will fit in |
245 | quite nicely into a call to C<pthread_atfork>: |
454 | quite nicely into a call to C<pthread_atfork>: |
246 | |
455 | |
247 | pthread_atfork (0, 0, ev_default_fork); |
456 | pthread_atfork (0, 0, ev_default_fork); |
248 | |
457 | |
|
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458 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
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459 | without calling this function, so if you force one of those backends you |
|
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460 | do not need to care. |
|
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461 | |
249 | =item ev_loop_fork (loop) |
462 | =item ev_loop_fork (loop) |
250 | |
463 | |
251 | Like C<ev_default_fork>, but acts on an event loop created by |
464 | Like C<ev_default_fork>, but acts on an event loop created by |
252 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
465 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
253 | after fork, and how you do this is entirely your own problem. |
466 | after fork, and how you do this is entirely your own problem. |
254 | |
467 | |
|
|
468 | =item unsigned int ev_loop_count (loop) |
|
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469 | |
|
|
470 | Returns the count of loop iterations for the loop, which is identical to |
|
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471 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
472 | happily wraps around with enough iterations. |
|
|
473 | |
|
|
474 | This value can sometimes be useful as a generation counter of sorts (it |
|
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475 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
476 | C<ev_prepare> and C<ev_check> calls. |
|
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477 | |
255 | =item unsigned int ev_method (loop) |
478 | =item unsigned int ev_backend (loop) |
256 | |
479 | |
257 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
480 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
258 | use. |
481 | use. |
259 | |
482 | |
260 | =item ev_tstamp ev_now (loop) |
483 | =item ev_tstamp ev_now (loop) |
261 | |
484 | |
262 | Returns the current "event loop time", which is the time the event loop |
485 | Returns the current "event loop time", which is the time the event loop |
263 | got events and started processing them. This timestamp does not change |
486 | received events and started processing them. This timestamp does not |
264 | as long as callbacks are being processed, and this is also the base time |
487 | change as long as callbacks are being processed, and this is also the base |
265 | used for relative timers. You can treat it as the timestamp of the event |
488 | time used for relative timers. You can treat it as the timestamp of the |
266 | occuring (or more correctly, the mainloop finding out about it). |
489 | event occurring (or more correctly, libev finding out about it). |
267 | |
490 | |
268 | =item ev_loop (loop, int flags) |
491 | =item ev_loop (loop, int flags) |
269 | |
492 | |
270 | Finally, this is it, the event handler. This function usually is called |
493 | Finally, this is it, the event handler. This function usually is called |
271 | after you initialised all your watchers and you want to start handling |
494 | after you initialised all your watchers and you want to start handling |
272 | events. |
495 | events. |
273 | |
496 | |
274 | If the flags argument is specified as 0, it will not return until either |
497 | If the flags argument is specified as C<0>, it will not return until |
275 | no event watchers are active anymore or C<ev_unloop> was called. |
498 | either no event watchers are active anymore or C<ev_unloop> was called. |
|
|
499 | |
|
|
500 | Please note that an explicit C<ev_unloop> is usually better than |
|
|
501 | relying on all watchers to be stopped when deciding when a program has |
|
|
502 | finished (especially in interactive programs), but having a program that |
|
|
503 | automatically loops as long as it has to and no longer by virtue of |
|
|
504 | relying on its watchers stopping correctly is a thing of beauty. |
276 | |
505 | |
277 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
506 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
278 | those events and any outstanding ones, but will not block your process in |
507 | those events and any outstanding ones, but will not block your process in |
279 | case there are no events and will return after one iteration of the loop. |
508 | case there are no events and will return after one iteration of the loop. |
280 | |
509 | |
281 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
510 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
282 | neccessary) and will handle those and any outstanding ones. It will block |
511 | neccessary) and will handle those and any outstanding ones. It will block |
283 | your process until at least one new event arrives, and will return after |
512 | your process until at least one new event arrives, and will return after |
284 | one iteration of the loop. |
513 | one iteration of the loop. This is useful if you are waiting for some |
|
|
514 | external event in conjunction with something not expressible using other |
|
|
515 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
|
|
516 | usually a better approach for this kind of thing. |
285 | |
517 | |
286 | This flags value could be used to implement alternative looping |
|
|
287 | constructs, but the C<prepare> and C<check> watchers provide a better and |
|
|
288 | more generic mechanism. |
|
|
289 | |
|
|
290 | Here are the gory details of what ev_loop does: |
518 | Here are the gory details of what C<ev_loop> does: |
291 | |
519 | |
|
|
520 | - Before the first iteration, call any pending watchers. |
292 | 1. If there are no active watchers (reference count is zero), return. |
521 | * If there are no active watchers (reference count is zero), return. |
293 | 2. Queue and immediately call all prepare watchers. |
522 | - Queue all prepare watchers and then call all outstanding watchers. |
294 | 3. If we have been forked, recreate the kernel state. |
523 | - If we have been forked, recreate the kernel state. |
295 | 4. Update the kernel state with all outstanding changes. |
524 | - Update the kernel state with all outstanding changes. |
296 | 5. Update the "event loop time". |
525 | - Update the "event loop time". |
297 | 6. Calculate for how long to block. |
526 | - Calculate for how long to block. |
298 | 7. Block the process, waiting for events. |
527 | - Block the process, waiting for any events. |
|
|
528 | - Queue all outstanding I/O (fd) events. |
299 | 8. Update the "event loop time" and do time jump handling. |
529 | - Update the "event loop time" and do time jump handling. |
300 | 9. Queue all outstanding timers. |
530 | - Queue all outstanding timers. |
301 | 10. Queue all outstanding periodics. |
531 | - Queue all outstanding periodics. |
302 | 11. If no events are pending now, queue all idle watchers. |
532 | - If no events are pending now, queue all idle watchers. |
303 | 12. Queue all check watchers. |
533 | - Queue all check watchers. |
304 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
534 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
535 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
536 | be handled here by queueing them when their watcher gets executed. |
305 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
537 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
306 | was used, return, otherwise continue with step #1. |
538 | were used, return, otherwise continue with step *. |
|
|
539 | |
|
|
540 | Example: Queue some jobs and then loop until no events are outsanding |
|
|
541 | anymore. |
|
|
542 | |
|
|
543 | ... queue jobs here, make sure they register event watchers as long |
|
|
544 | ... as they still have work to do (even an idle watcher will do..) |
|
|
545 | ev_loop (my_loop, 0); |
|
|
546 | ... jobs done. yeah! |
307 | |
547 | |
308 | =item ev_unloop (loop, how) |
548 | =item ev_unloop (loop, how) |
309 | |
549 | |
310 | Can be used to make a call to C<ev_loop> return early (but only after it |
550 | Can be used to make a call to C<ev_loop> return early (but only after it |
311 | has processed all outstanding events). The C<how> argument must be either |
551 | has processed all outstanding events). The C<how> argument must be either |
… | |
… | |
325 | visible to the libev user and should not keep C<ev_loop> from exiting if |
565 | visible to the libev user and should not keep C<ev_loop> from exiting if |
326 | no event watchers registered by it are active. It is also an excellent |
566 | no event watchers registered by it are active. It is also an excellent |
327 | way to do this for generic recurring timers or from within third-party |
567 | way to do this for generic recurring timers or from within third-party |
328 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
568 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
329 | |
569 | |
|
|
570 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
|
|
571 | running when nothing else is active. |
|
|
572 | |
|
|
573 | struct ev_signal exitsig; |
|
|
574 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
575 | ev_signal_start (loop, &exitsig); |
|
|
576 | evf_unref (loop); |
|
|
577 | |
|
|
578 | Example: For some weird reason, unregister the above signal handler again. |
|
|
579 | |
|
|
580 | ev_ref (loop); |
|
|
581 | ev_signal_stop (loop, &exitsig); |
|
|
582 | |
|
|
583 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
584 | |
|
|
585 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
586 | |
|
|
587 | These advanced functions influence the time that libev will spend waiting |
|
|
588 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
589 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
590 | |
|
|
591 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
592 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
593 | increase efficiency of loop iterations. |
|
|
594 | |
|
|
595 | The background is that sometimes your program runs just fast enough to |
|
|
596 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
597 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
598 | events, especially with backends like C<select ()> which have a high |
|
|
599 | overhead for the actual polling but can deliver many events at once. |
|
|
600 | |
|
|
601 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
602 | time collecting I/O events, so you can handle more events per iteration, |
|
|
603 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
604 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
605 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
606 | |
|
|
607 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
608 | to spend more time collecting timeouts, at the expense of increased |
|
|
609 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
610 | will not be affected. Setting this to a non-null value will not introduce |
|
|
611 | any overhead in libev. |
|
|
612 | |
|
|
613 | Many (busy) programs can usually benefit by setting the io collect |
|
|
614 | interval to a value near C<0.1> or so, which is often enough for |
|
|
615 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
616 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
617 | as this approsaches the timing granularity of most systems. |
|
|
618 | |
330 | =back |
619 | =back |
|
|
620 | |
331 | |
621 | |
332 | =head1 ANATOMY OF A WATCHER |
622 | =head1 ANATOMY OF A WATCHER |
333 | |
623 | |
334 | A watcher is a structure that you create and register to record your |
624 | A watcher is a structure that you create and register to record your |
335 | interest in some event. For instance, if you want to wait for STDIN to |
625 | interest in some event. For instance, if you want to wait for STDIN to |
… | |
… | |
368 | *) >>), and you can stop watching for events at any time by calling the |
658 | *) >>), and you can stop watching for events at any time by calling the |
369 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
659 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
370 | |
660 | |
371 | As long as your watcher is active (has been started but not stopped) you |
661 | As long as your watcher is active (has been started but not stopped) you |
372 | must not touch the values stored in it. Most specifically you must never |
662 | must not touch the values stored in it. Most specifically you must never |
373 | reinitialise it or call its set method. |
663 | reinitialise it or call its C<set> macro. |
374 | |
|
|
375 | You can check whether an event is active by calling the C<ev_is_active |
|
|
376 | (watcher *)> macro. To see whether an event is outstanding (but the |
|
|
377 | callback for it has not been called yet) you can use the C<ev_is_pending |
|
|
378 | (watcher *)> macro. |
|
|
379 | |
664 | |
380 | Each and every callback receives the event loop pointer as first, the |
665 | Each and every callback receives the event loop pointer as first, the |
381 | registered watcher structure as second, and a bitset of received events as |
666 | registered watcher structure as second, and a bitset of received events as |
382 | third argument. |
667 | third argument. |
383 | |
668 | |
… | |
… | |
407 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
692 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
408 | |
693 | |
409 | =item C<EV_CHILD> |
694 | =item C<EV_CHILD> |
410 | |
695 | |
411 | The pid specified in the C<ev_child> watcher has received a status change. |
696 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
697 | |
|
|
698 | =item C<EV_STAT> |
|
|
699 | |
|
|
700 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
412 | |
701 | |
413 | =item C<EV_IDLE> |
702 | =item C<EV_IDLE> |
414 | |
703 | |
415 | The C<ev_idle> watcher has determined that you have nothing better to do. |
704 | The C<ev_idle> watcher has determined that you have nothing better to do. |
416 | |
705 | |
… | |
… | |
424 | received events. Callbacks of both watcher types can start and stop as |
713 | received events. Callbacks of both watcher types can start and stop as |
425 | many watchers as they want, and all of them will be taken into account |
714 | many watchers as they want, and all of them will be taken into account |
426 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
715 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
427 | C<ev_loop> from blocking). |
716 | C<ev_loop> from blocking). |
428 | |
717 | |
|
|
718 | =item C<EV_EMBED> |
|
|
719 | |
|
|
720 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
|
|
721 | |
|
|
722 | =item C<EV_FORK> |
|
|
723 | |
|
|
724 | The event loop has been resumed in the child process after fork (see |
|
|
725 | C<ev_fork>). |
|
|
726 | |
429 | =item C<EV_ERROR> |
727 | =item C<EV_ERROR> |
430 | |
728 | |
431 | An unspecified error has occured, the watcher has been stopped. This might |
729 | An unspecified error has occured, the watcher has been stopped. This might |
432 | happen because the watcher could not be properly started because libev |
730 | happen because the watcher could not be properly started because libev |
433 | ran out of memory, a file descriptor was found to be closed or any other |
731 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
439 | your callbacks is well-written it can just attempt the operation and cope |
737 | your callbacks is well-written it can just attempt the operation and cope |
440 | with the error from read() or write(). This will not work in multithreaded |
738 | with the error from read() or write(). This will not work in multithreaded |
441 | programs, though, so beware. |
739 | programs, though, so beware. |
442 | |
740 | |
443 | =back |
741 | =back |
|
|
742 | |
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|
743 | =head2 GENERIC WATCHER FUNCTIONS |
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744 | |
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745 | In the following description, C<TYPE> stands for the watcher type, |
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746 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
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747 | |
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748 | =over 4 |
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749 | |
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750 | =item C<ev_init> (ev_TYPE *watcher, callback) |
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751 | |
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752 | This macro initialises the generic portion of a watcher. The contents |
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753 | of the watcher object can be arbitrary (so C<malloc> will do). Only |
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754 | the generic parts of the watcher are initialised, you I<need> to call |
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755 | the type-specific C<ev_TYPE_set> macro afterwards to initialise the |
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756 | type-specific parts. For each type there is also a C<ev_TYPE_init> macro |
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757 | which rolls both calls into one. |
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758 | |
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759 | You can reinitialise a watcher at any time as long as it has been stopped |
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760 | (or never started) and there are no pending events outstanding. |
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761 | |
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762 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
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763 | int revents)>. |
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764 | |
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765 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
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766 | |
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767 | This macro initialises the type-specific parts of a watcher. You need to |
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768 | call C<ev_init> at least once before you call this macro, but you can |
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769 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
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770 | macro on a watcher that is active (it can be pending, however, which is a |
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771 | difference to the C<ev_init> macro). |
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772 | |
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773 | Although some watcher types do not have type-specific arguments |
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774 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
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775 | |
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776 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
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777 | |
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778 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
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779 | calls into a single call. This is the most convinient method to initialise |
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780 | a watcher. The same limitations apply, of course. |
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781 | |
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782 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
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783 | |
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784 | Starts (activates) the given watcher. Only active watchers will receive |
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785 | events. If the watcher is already active nothing will happen. |
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786 | |
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787 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
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788 | |
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789 | Stops the given watcher again (if active) and clears the pending |
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790 | status. It is possible that stopped watchers are pending (for example, |
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791 | non-repeating timers are being stopped when they become pending), but |
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792 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
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793 | you want to free or reuse the memory used by the watcher it is therefore a |
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794 | good idea to always call its C<ev_TYPE_stop> function. |
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795 | |
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796 | =item bool ev_is_active (ev_TYPE *watcher) |
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797 | |
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798 | Returns a true value iff the watcher is active (i.e. it has been started |
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799 | and not yet been stopped). As long as a watcher is active you must not modify |
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800 | it. |
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801 | |
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802 | =item bool ev_is_pending (ev_TYPE *watcher) |
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803 | |
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804 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
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805 | events but its callback has not yet been invoked). As long as a watcher |
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806 | is pending (but not active) you must not call an init function on it (but |
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807 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
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808 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
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809 | it). |
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810 | |
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811 | =item callback ev_cb (ev_TYPE *watcher) |
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812 | |
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813 | Returns the callback currently set on the watcher. |
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814 | |
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815 | =item ev_cb_set (ev_TYPE *watcher, callback) |
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816 | |
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817 | Change the callback. You can change the callback at virtually any time |
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818 | (modulo threads). |
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819 | |
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820 | =item ev_set_priority (ev_TYPE *watcher, priority) |
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821 | |
|
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822 | =item int ev_priority (ev_TYPE *watcher) |
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823 | |
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824 | Set and query the priority of the watcher. The priority is a small |
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825 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
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826 | (default: C<-2>). Pending watchers with higher priority will be invoked |
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827 | before watchers with lower priority, but priority will not keep watchers |
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828 | from being executed (except for C<ev_idle> watchers). |
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829 | |
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830 | This means that priorities are I<only> used for ordering callback |
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831 | invocation after new events have been received. This is useful, for |
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832 | example, to reduce latency after idling, or more often, to bind two |
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833 | watchers on the same event and make sure one is called first. |
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834 | |
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835 | If you need to suppress invocation when higher priority events are pending |
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836 | you need to look at C<ev_idle> watchers, which provide this functionality. |
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837 | |
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838 | You I<must not> change the priority of a watcher as long as it is active or |
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839 | pending. |
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840 | |
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841 | The default priority used by watchers when no priority has been set is |
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842 | always C<0>, which is supposed to not be too high and not be too low :). |
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843 | |
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844 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
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845 | fine, as long as you do not mind that the priority value you query might |
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846 | or might not have been adjusted to be within valid range. |
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847 | |
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848 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
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849 | |
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850 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
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851 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
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852 | can deal with that fact. |
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853 | |
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854 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
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855 | |
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856 | If the watcher is pending, this function returns clears its pending status |
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857 | and returns its C<revents> bitset (as if its callback was invoked). If the |
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858 | watcher isn't pending it does nothing and returns C<0>. |
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859 | |
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860 | =back |
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861 | |
444 | |
862 | |
445 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
863 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
446 | |
864 | |
447 | Each watcher has, by default, a member C<void *data> that you can change |
865 | Each watcher has, by default, a member C<void *data> that you can change |
448 | and read at any time, libev will completely ignore it. This can be used |
866 | and read at any time, libev will completely ignore it. This can be used |
… | |
… | |
466 | { |
884 | { |
467 | struct my_io *w = (struct my_io *)w_; |
885 | struct my_io *w = (struct my_io *)w_; |
468 | ... |
886 | ... |
469 | } |
887 | } |
470 | |
888 | |
471 | More interesting and less C-conformant ways of catsing your callback type |
889 | More interesting and less C-conformant ways of casting your callback type |
472 | have been omitted.... |
890 | instead have been omitted. |
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891 | |
|
|
892 | Another common scenario is having some data structure with multiple |
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893 | watchers: |
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894 | |
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895 | struct my_biggy |
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896 | { |
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897 | int some_data; |
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898 | ev_timer t1; |
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899 | ev_timer t2; |
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900 | } |
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901 | |
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902 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
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903 | you need to use C<offsetof>: |
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904 | |
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905 | #include <stddef.h> |
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906 | |
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907 | static void |
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908 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
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909 | { |
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910 | struct my_biggy big = (struct my_biggy * |
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911 | (((char *)w) - offsetof (struct my_biggy, t1)); |
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912 | } |
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913 | |
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914 | static void |
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915 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
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916 | { |
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917 | struct my_biggy big = (struct my_biggy * |
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918 | (((char *)w) - offsetof (struct my_biggy, t2)); |
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919 | } |
473 | |
920 | |
474 | |
921 | |
475 | =head1 WATCHER TYPES |
922 | =head1 WATCHER TYPES |
476 | |
923 | |
477 | This section describes each watcher in detail, but will not repeat |
924 | This section describes each watcher in detail, but will not repeat |
478 | information given in the last section. |
925 | information given in the last section. Any initialisation/set macros, |
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926 | functions and members specific to the watcher type are explained. |
479 | |
927 | |
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928 | Members are additionally marked with either I<[read-only]>, meaning that, |
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929 | while the watcher is active, you can look at the member and expect some |
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930 | sensible content, but you must not modify it (you can modify it while the |
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931 | watcher is stopped to your hearts content), or I<[read-write]>, which |
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932 | means you can expect it to have some sensible content while the watcher |
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933 | is active, but you can also modify it. Modifying it may not do something |
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934 | sensible or take immediate effect (or do anything at all), but libev will |
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935 | not crash or malfunction in any way. |
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936 | |
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937 | |
480 | =head2 C<ev_io> - is this file descriptor readable or writable |
938 | =head2 C<ev_io> - is this file descriptor readable or writable? |
481 | |
939 | |
482 | I/O watchers check whether a file descriptor is readable or writable |
940 | I/O watchers check whether a file descriptor is readable or writable |
483 | in each iteration of the event loop (This behaviour is called |
941 | in each iteration of the event loop, or, more precisely, when reading |
484 | level-triggering because you keep receiving events as long as the |
942 | would not block the process and writing would at least be able to write |
485 | condition persists. Remember you can stop the watcher if you don't want to |
943 | some data. This behaviour is called level-triggering because you keep |
486 | act on the event and neither want to receive future events). |
944 | receiving events as long as the condition persists. Remember you can stop |
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945 | the watcher if you don't want to act on the event and neither want to |
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946 | receive future events. |
487 | |
947 | |
488 | In general you can register as many read and/or write event watchers per |
948 | In general you can register as many read and/or write event watchers per |
489 | fd as you want (as long as you don't confuse yourself). Setting all file |
949 | fd as you want (as long as you don't confuse yourself). Setting all file |
490 | descriptors to non-blocking mode is also usually a good idea (but not |
950 | descriptors to non-blocking mode is also usually a good idea (but not |
491 | required if you know what you are doing). |
951 | required if you know what you are doing). |
492 | |
952 | |
493 | You have to be careful with dup'ed file descriptors, though. Some backends |
953 | You have to be careful with dup'ed file descriptors, though. Some backends |
494 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
954 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
495 | descriptors correctly if you register interest in two or more fds pointing |
955 | descriptors correctly if you register interest in two or more fds pointing |
496 | to the same underlying file/socket etc. description (that is, they share |
956 | to the same underlying file/socket/etc. description (that is, they share |
497 | the same underlying "file open"). |
957 | the same underlying "file open"). |
498 | |
958 | |
499 | If you must do this, then force the use of a known-to-be-good backend |
959 | If you must do this, then force the use of a known-to-be-good backend |
500 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
960 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
501 | EVMETHOD_POLL). |
961 | C<EVBACKEND_POLL>). |
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962 | |
|
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963 | Another thing you have to watch out for is that it is quite easy to |
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964 | receive "spurious" readyness notifications, that is your callback might |
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965 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
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966 | because there is no data. Not only are some backends known to create a |
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967 | lot of those (for example solaris ports), it is very easy to get into |
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968 | this situation even with a relatively standard program structure. Thus |
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969 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
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970 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
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971 | |
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972 | If you cannot run the fd in non-blocking mode (for example you should not |
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973 | play around with an Xlib connection), then you have to seperately re-test |
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974 | whether a file descriptor is really ready with a known-to-be good interface |
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975 | such as poll (fortunately in our Xlib example, Xlib already does this on |
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976 | its own, so its quite safe to use). |
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977 | |
|
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978 | =head3 The special problem of disappearing file descriptors |
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979 | |
|
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980 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
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981 | descriptor (either by calling C<close> explicitly or by any other means, |
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982 | such as C<dup>). The reason is that you register interest in some file |
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983 | descriptor, but when it goes away, the operating system will silently drop |
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984 | this interest. If another file descriptor with the same number then is |
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985 | registered with libev, there is no efficient way to see that this is, in |
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986 | fact, a different file descriptor. |
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987 | |
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988 | To avoid having to explicitly tell libev about such cases, libev follows |
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989 | the following policy: Each time C<ev_io_set> is being called, libev |
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990 | will assume that this is potentially a new file descriptor, otherwise |
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991 | it is assumed that the file descriptor stays the same. That means that |
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992 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
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993 | descriptor even if the file descriptor number itself did not change. |
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994 | |
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995 | This is how one would do it normally anyway, the important point is that |
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996 | the libev application should not optimise around libev but should leave |
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997 | optimisations to libev. |
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998 | |
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999 | =head3 The special problem of dup'ed file descriptors |
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1000 | |
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1001 | Some backends (e.g. epoll), cannot register events for file descriptors, |
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1002 | but only events for the underlying file descriptions. That menas when you |
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1003 | have C<dup ()>'ed file descriptors and register events for them, only one |
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1004 | file descriptor might actually receive events. |
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1005 | |
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1006 | There is no workaorund possible except not registering events |
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1007 | for potentially C<dup ()>'ed file descriptors or to resort to |
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1008 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
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1009 | |
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1010 | =head3 The special problem of fork |
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1011 | |
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1012 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
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1013 | useless behaviour. Libev fully supports fork, but needs to be told about |
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1014 | it in the child. |
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1015 | |
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1016 | To support fork in your programs, you either have to call |
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1017 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
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1018 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
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1019 | C<EVBACKEND_POLL>. |
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1020 | |
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1021 | |
|
|
1022 | =head3 Watcher-Specific Functions |
502 | |
1023 | |
503 | =over 4 |
1024 | =over 4 |
504 | |
1025 | |
505 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1026 | =item ev_io_init (ev_io *, callback, int fd, int events) |
506 | |
1027 | |
507 | =item ev_io_set (ev_io *, int fd, int events) |
1028 | =item ev_io_set (ev_io *, int fd, int events) |
508 | |
1029 | |
509 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
1030 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
510 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
1031 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
511 | EV_WRITE> to receive the given events. |
1032 | C<EV_READ | EV_WRITE> to receive the given events. |
|
|
1033 | |
|
|
1034 | =item int fd [read-only] |
|
|
1035 | |
|
|
1036 | The file descriptor being watched. |
|
|
1037 | |
|
|
1038 | =item int events [read-only] |
|
|
1039 | |
|
|
1040 | The events being watched. |
512 | |
1041 | |
513 | =back |
1042 | =back |
514 | |
1043 | |
|
|
1044 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
|
|
1045 | readable, but only once. Since it is likely line-buffered, you could |
|
|
1046 | attempt to read a whole line in the callback. |
|
|
1047 | |
|
|
1048 | static void |
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1049 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1050 | { |
|
|
1051 | ev_io_stop (loop, w); |
|
|
1052 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
1053 | } |
|
|
1054 | |
|
|
1055 | ... |
|
|
1056 | struct ev_loop *loop = ev_default_init (0); |
|
|
1057 | struct ev_io stdin_readable; |
|
|
1058 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
1059 | ev_io_start (loop, &stdin_readable); |
|
|
1060 | ev_loop (loop, 0); |
|
|
1061 | |
|
|
1062 | |
515 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
1063 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
516 | |
1064 | |
517 | Timer watchers are simple relative timers that generate an event after a |
1065 | Timer watchers are simple relative timers that generate an event after a |
518 | given time, and optionally repeating in regular intervals after that. |
1066 | given time, and optionally repeating in regular intervals after that. |
519 | |
1067 | |
520 | The timers are based on real time, that is, if you register an event that |
1068 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
533 | |
1081 | |
534 | The callback is guarenteed to be invoked only when its timeout has passed, |
1082 | The callback is guarenteed to be invoked only when its timeout has passed, |
535 | but if multiple timers become ready during the same loop iteration then |
1083 | but if multiple timers become ready during the same loop iteration then |
536 | order of execution is undefined. |
1084 | order of execution is undefined. |
537 | |
1085 | |
|
|
1086 | =head3 Watcher-Specific Functions and Data Members |
|
|
1087 | |
538 | =over 4 |
1088 | =over 4 |
539 | |
1089 | |
540 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1090 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
541 | |
1091 | |
542 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1092 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
555 | =item ev_timer_again (loop) |
1105 | =item ev_timer_again (loop) |
556 | |
1106 | |
557 | This will act as if the timer timed out and restart it again if it is |
1107 | This will act as if the timer timed out and restart it again if it is |
558 | repeating. The exact semantics are: |
1108 | repeating. The exact semantics are: |
559 | |
1109 | |
|
|
1110 | If the timer is pending, its pending status is cleared. |
|
|
1111 | |
560 | If the timer is started but nonrepeating, stop it. |
1112 | If the timer is started but nonrepeating, stop it (as if it timed out). |
561 | |
1113 | |
562 | If the timer is repeating, either start it if necessary (with the repeat |
1114 | If the timer is repeating, either start it if necessary (with the |
563 | value), or reset the running timer to the repeat value. |
1115 | C<repeat> value), or reset the running timer to the C<repeat> value. |
564 | |
1116 | |
565 | This sounds a bit complicated, but here is a useful and typical |
1117 | This sounds a bit complicated, but here is a useful and typical |
566 | example: Imagine you have a tcp connection and you want a so-called idle |
1118 | example: Imagine you have a tcp connection and you want a so-called idle |
567 | timeout, that is, you want to be called when there have been, say, 60 |
1119 | timeout, that is, you want to be called when there have been, say, 60 |
568 | seconds of inactivity on the socket. The easiest way to do this is to |
1120 | seconds of inactivity on the socket. The easiest way to do this is to |
569 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
1121 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
570 | time you successfully read or write some data. If you go into an idle |
1122 | C<ev_timer_again> each time you successfully read or write some data. If |
571 | state where you do not expect data to travel on the socket, you can stop |
1123 | you go into an idle state where you do not expect data to travel on the |
572 | the timer, and again will automatically restart it if need be. |
1124 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
1125 | automatically restart it if need be. |
|
|
1126 | |
|
|
1127 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1128 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1129 | |
|
|
1130 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1131 | ev_timer_again (loop, timer); |
|
|
1132 | ... |
|
|
1133 | timer->again = 17.; |
|
|
1134 | ev_timer_again (loop, timer); |
|
|
1135 | ... |
|
|
1136 | timer->again = 10.; |
|
|
1137 | ev_timer_again (loop, timer); |
|
|
1138 | |
|
|
1139 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1140 | you want to modify its timeout value. |
|
|
1141 | |
|
|
1142 | =item ev_tstamp repeat [read-write] |
|
|
1143 | |
|
|
1144 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
1145 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
1146 | which is also when any modifications are taken into account. |
573 | |
1147 | |
574 | =back |
1148 | =back |
575 | |
1149 | |
|
|
1150 | Example: Create a timer that fires after 60 seconds. |
|
|
1151 | |
|
|
1152 | static void |
|
|
1153 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1154 | { |
|
|
1155 | .. one minute over, w is actually stopped right here |
|
|
1156 | } |
|
|
1157 | |
|
|
1158 | struct ev_timer mytimer; |
|
|
1159 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
1160 | ev_timer_start (loop, &mytimer); |
|
|
1161 | |
|
|
1162 | Example: Create a timeout timer that times out after 10 seconds of |
|
|
1163 | inactivity. |
|
|
1164 | |
|
|
1165 | static void |
|
|
1166 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1167 | { |
|
|
1168 | .. ten seconds without any activity |
|
|
1169 | } |
|
|
1170 | |
|
|
1171 | struct ev_timer mytimer; |
|
|
1172 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
1173 | ev_timer_again (&mytimer); /* start timer */ |
|
|
1174 | ev_loop (loop, 0); |
|
|
1175 | |
|
|
1176 | // and in some piece of code that gets executed on any "activity": |
|
|
1177 | // reset the timeout to start ticking again at 10 seconds |
|
|
1178 | ev_timer_again (&mytimer); |
|
|
1179 | |
|
|
1180 | |
576 | =head2 C<ev_periodic> - to cron or not to cron |
1181 | =head2 C<ev_periodic> - to cron or not to cron? |
577 | |
1182 | |
578 | Periodic watchers are also timers of a kind, but they are very versatile |
1183 | Periodic watchers are also timers of a kind, but they are very versatile |
579 | (and unfortunately a bit complex). |
1184 | (and unfortunately a bit complex). |
580 | |
1185 | |
581 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1186 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
582 | but on wallclock time (absolute time). You can tell a periodic watcher |
1187 | but on wallclock time (absolute time). You can tell a periodic watcher |
583 | to trigger "at" some specific point in time. For example, if you tell a |
1188 | to trigger "at" some specific point in time. For example, if you tell a |
584 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
1189 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
585 | + 10.>) and then reset your system clock to the last year, then it will |
1190 | + 10.>) and then reset your system clock to the last year, then it will |
586 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1191 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
587 | roughly 10 seconds later and of course not if you reset your system time |
1192 | roughly 10 seconds later). |
588 | again). |
|
|
589 | |
1193 | |
590 | They can also be used to implement vastly more complex timers, such as |
1194 | They can also be used to implement vastly more complex timers, such as |
591 | triggering an event on eahc midnight, local time. |
1195 | triggering an event on each midnight, local time or other, complicated, |
|
|
1196 | rules. |
592 | |
1197 | |
593 | As with timers, the callback is guarenteed to be invoked only when the |
1198 | As with timers, the callback is guarenteed to be invoked only when the |
594 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1199 | time (C<at>) has been passed, but if multiple periodic timers become ready |
595 | during the same loop iteration then order of execution is undefined. |
1200 | during the same loop iteration then order of execution is undefined. |
596 | |
1201 | |
|
|
1202 | =head3 Watcher-Specific Functions and Data Members |
|
|
1203 | |
597 | =over 4 |
1204 | =over 4 |
598 | |
1205 | |
599 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1206 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
600 | |
1207 | |
601 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1208 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
603 | Lots of arguments, lets sort it out... There are basically three modes of |
1210 | Lots of arguments, lets sort it out... There are basically three modes of |
604 | operation, and we will explain them from simplest to complex: |
1211 | operation, and we will explain them from simplest to complex: |
605 | |
1212 | |
606 | =over 4 |
1213 | =over 4 |
607 | |
1214 | |
608 | =item * absolute timer (interval = reschedule_cb = 0) |
1215 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
609 | |
1216 | |
610 | In this configuration the watcher triggers an event at the wallclock time |
1217 | In this configuration the watcher triggers an event at the wallclock time |
611 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1218 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
612 | that is, if it is to be run at January 1st 2011 then it will run when the |
1219 | that is, if it is to be run at January 1st 2011 then it will run when the |
613 | system time reaches or surpasses this time. |
1220 | system time reaches or surpasses this time. |
614 | |
1221 | |
615 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1222 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
616 | |
1223 | |
617 | In this mode the watcher will always be scheduled to time out at the next |
1224 | In this mode the watcher will always be scheduled to time out at the next |
618 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1225 | C<at + N * interval> time (for some integer N, which can also be negative) |
619 | of any time jumps. |
1226 | and then repeat, regardless of any time jumps. |
620 | |
1227 | |
621 | This can be used to create timers that do not drift with respect to system |
1228 | This can be used to create timers that do not drift with respect to system |
622 | time: |
1229 | time: |
623 | |
1230 | |
624 | ev_periodic_set (&periodic, 0., 3600., 0); |
1231 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
630 | |
1237 | |
631 | Another way to think about it (for the mathematically inclined) is that |
1238 | Another way to think about it (for the mathematically inclined) is that |
632 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1239 | C<ev_periodic> will try to run the callback in this mode at the next possible |
633 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1240 | time where C<time = at (mod interval)>, regardless of any time jumps. |
634 | |
1241 | |
|
|
1242 | For numerical stability it is preferable that the C<at> value is near |
|
|
1243 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1244 | this value. |
|
|
1245 | |
635 | =item * manual reschedule mode (reschedule_cb = callback) |
1246 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
636 | |
1247 | |
637 | In this mode the values for C<interval> and C<at> are both being |
1248 | In this mode the values for C<interval> and C<at> are both being |
638 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1249 | ignored. Instead, each time the periodic watcher gets scheduled, the |
639 | reschedule callback will be called with the watcher as first, and the |
1250 | reschedule callback will be called with the watcher as first, and the |
640 | current time as second argument. |
1251 | current time as second argument. |
641 | |
1252 | |
642 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1253 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
643 | ever, or make any event loop modifications>. If you need to stop it, |
1254 | ever, or make any event loop modifications>. If you need to stop it, |
644 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1255 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
645 | starting a prepare watcher). |
1256 | starting an C<ev_prepare> watcher, which is legal). |
646 | |
1257 | |
647 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1258 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
648 | ev_tstamp now)>, e.g.: |
1259 | ev_tstamp now)>, e.g.: |
649 | |
1260 | |
650 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1261 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
673 | Simply stops and restarts the periodic watcher again. This is only useful |
1284 | Simply stops and restarts the periodic watcher again. This is only useful |
674 | when you changed some parameters or the reschedule callback would return |
1285 | when you changed some parameters or the reschedule callback would return |
675 | a different time than the last time it was called (e.g. in a crond like |
1286 | a different time than the last time it was called (e.g. in a crond like |
676 | program when the crontabs have changed). |
1287 | program when the crontabs have changed). |
677 | |
1288 | |
|
|
1289 | =item ev_tstamp offset [read-write] |
|
|
1290 | |
|
|
1291 | When repeating, this contains the offset value, otherwise this is the |
|
|
1292 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1293 | |
|
|
1294 | Can be modified any time, but changes only take effect when the periodic |
|
|
1295 | timer fires or C<ev_periodic_again> is being called. |
|
|
1296 | |
|
|
1297 | =item ev_tstamp interval [read-write] |
|
|
1298 | |
|
|
1299 | The current interval value. Can be modified any time, but changes only |
|
|
1300 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1301 | called. |
|
|
1302 | |
|
|
1303 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1304 | |
|
|
1305 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1306 | switched off. Can be changed any time, but changes only take effect when |
|
|
1307 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1308 | |
|
|
1309 | =item ev_tstamp at [read-only] |
|
|
1310 | |
|
|
1311 | When active, contains the absolute time that the watcher is supposed to |
|
|
1312 | trigger next. |
|
|
1313 | |
678 | =back |
1314 | =back |
679 | |
1315 | |
|
|
1316 | Example: Call a callback every hour, or, more precisely, whenever the |
|
|
1317 | system clock is divisible by 3600. The callback invocation times have |
|
|
1318 | potentially a lot of jittering, but good long-term stability. |
|
|
1319 | |
|
|
1320 | static void |
|
|
1321 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1322 | { |
|
|
1323 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
1324 | } |
|
|
1325 | |
|
|
1326 | struct ev_periodic hourly_tick; |
|
|
1327 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
1328 | ev_periodic_start (loop, &hourly_tick); |
|
|
1329 | |
|
|
1330 | Example: The same as above, but use a reschedule callback to do it: |
|
|
1331 | |
|
|
1332 | #include <math.h> |
|
|
1333 | |
|
|
1334 | static ev_tstamp |
|
|
1335 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1336 | { |
|
|
1337 | return fmod (now, 3600.) + 3600.; |
|
|
1338 | } |
|
|
1339 | |
|
|
1340 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1341 | |
|
|
1342 | Example: Call a callback every hour, starting now: |
|
|
1343 | |
|
|
1344 | struct ev_periodic hourly_tick; |
|
|
1345 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1346 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1347 | ev_periodic_start (loop, &hourly_tick); |
|
|
1348 | |
|
|
1349 | |
680 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1350 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
681 | |
1351 | |
682 | Signal watchers will trigger an event when the process receives a specific |
1352 | Signal watchers will trigger an event when the process receives a specific |
683 | signal one or more times. Even though signals are very asynchronous, libev |
1353 | signal one or more times. Even though signals are very asynchronous, libev |
684 | will try it's best to deliver signals synchronously, i.e. as part of the |
1354 | will try it's best to deliver signals synchronously, i.e. as part of the |
685 | normal event processing, like any other event. |
1355 | normal event processing, like any other event. |
… | |
… | |
689 | with the kernel (thus it coexists with your own signal handlers as long |
1359 | with the kernel (thus it coexists with your own signal handlers as long |
690 | as you don't register any with libev). Similarly, when the last signal |
1360 | as you don't register any with libev). Similarly, when the last signal |
691 | watcher for a signal is stopped libev will reset the signal handler to |
1361 | watcher for a signal is stopped libev will reset the signal handler to |
692 | SIG_DFL (regardless of what it was set to before). |
1362 | SIG_DFL (regardless of what it was set to before). |
693 | |
1363 | |
|
|
1364 | =head3 Watcher-Specific Functions and Data Members |
|
|
1365 | |
694 | =over 4 |
1366 | =over 4 |
695 | |
1367 | |
696 | =item ev_signal_init (ev_signal *, callback, int signum) |
1368 | =item ev_signal_init (ev_signal *, callback, int signum) |
697 | |
1369 | |
698 | =item ev_signal_set (ev_signal *, int signum) |
1370 | =item ev_signal_set (ev_signal *, int signum) |
699 | |
1371 | |
700 | Configures the watcher to trigger on the given signal number (usually one |
1372 | Configures the watcher to trigger on the given signal number (usually one |
701 | of the C<SIGxxx> constants). |
1373 | of the C<SIGxxx> constants). |
702 | |
1374 | |
|
|
1375 | =item int signum [read-only] |
|
|
1376 | |
|
|
1377 | The signal the watcher watches out for. |
|
|
1378 | |
703 | =back |
1379 | =back |
704 | |
1380 | |
|
|
1381 | |
705 | =head2 C<ev_child> - wait for pid status changes |
1382 | =head2 C<ev_child> - watch out for process status changes |
706 | |
1383 | |
707 | Child watchers trigger when your process receives a SIGCHLD in response to |
1384 | Child watchers trigger when your process receives a SIGCHLD in response to |
708 | some child status changes (most typically when a child of yours dies). |
1385 | some child status changes (most typically when a child of yours dies). |
|
|
1386 | |
|
|
1387 | =head3 Watcher-Specific Functions and Data Members |
709 | |
1388 | |
710 | =over 4 |
1389 | =over 4 |
711 | |
1390 | |
712 | =item ev_child_init (ev_child *, callback, int pid) |
1391 | =item ev_child_init (ev_child *, callback, int pid) |
713 | |
1392 | |
… | |
… | |
718 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1397 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
719 | the status word (use the macros from C<sys/wait.h> and see your systems |
1398 | the status word (use the macros from C<sys/wait.h> and see your systems |
720 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1399 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
721 | process causing the status change. |
1400 | process causing the status change. |
722 | |
1401 | |
|
|
1402 | =item int pid [read-only] |
|
|
1403 | |
|
|
1404 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1405 | |
|
|
1406 | =item int rpid [read-write] |
|
|
1407 | |
|
|
1408 | The process id that detected a status change. |
|
|
1409 | |
|
|
1410 | =item int rstatus [read-write] |
|
|
1411 | |
|
|
1412 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1413 | C<waitpid> and C<sys/wait.h> documentation for details). |
|
|
1414 | |
723 | =back |
1415 | =back |
724 | |
1416 | |
|
|
1417 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1418 | |
|
|
1419 | static void |
|
|
1420 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1421 | { |
|
|
1422 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1423 | } |
|
|
1424 | |
|
|
1425 | struct ev_signal signal_watcher; |
|
|
1426 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1427 | ev_signal_start (loop, &sigint_cb); |
|
|
1428 | |
|
|
1429 | |
|
|
1430 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1431 | |
|
|
1432 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1433 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1434 | compared to the last time, invoking the callback if it did. |
|
|
1435 | |
|
|
1436 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1437 | not exist" is a status change like any other. The condition "path does |
|
|
1438 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1439 | otherwise always forced to be at least one) and all the other fields of |
|
|
1440 | the stat buffer having unspecified contents. |
|
|
1441 | |
|
|
1442 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1443 | relative and your working directory changes, the behaviour is undefined. |
|
|
1444 | |
|
|
1445 | Since there is no standard to do this, the portable implementation simply |
|
|
1446 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
|
|
1447 | can specify a recommended polling interval for this case. If you specify |
|
|
1448 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1449 | unspecified default> value will be used (which you can expect to be around |
|
|
1450 | five seconds, although this might change dynamically). Libev will also |
|
|
1451 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1452 | usually overkill. |
|
|
1453 | |
|
|
1454 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1455 | as even with OS-supported change notifications, this can be |
|
|
1456 | resource-intensive. |
|
|
1457 | |
|
|
1458 | At the time of this writing, only the Linux inotify interface is |
|
|
1459 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1460 | reader). Inotify will be used to give hints only and should not change the |
|
|
1461 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1462 | to fall back to regular polling again even with inotify, but changes are |
|
|
1463 | usually detected immediately, and if the file exists there will be no |
|
|
1464 | polling. |
|
|
1465 | |
|
|
1466 | =head3 Watcher-Specific Functions and Data Members |
|
|
1467 | |
|
|
1468 | =over 4 |
|
|
1469 | |
|
|
1470 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1471 | |
|
|
1472 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1473 | |
|
|
1474 | Configures the watcher to wait for status changes of the given |
|
|
1475 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1476 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1477 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1478 | path for as long as the watcher is active. |
|
|
1479 | |
|
|
1480 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1481 | relative to the attributes at the time the watcher was started (or the |
|
|
1482 | last change was detected). |
|
|
1483 | |
|
|
1484 | =item ev_stat_stat (ev_stat *) |
|
|
1485 | |
|
|
1486 | Updates the stat buffer immediately with new values. If you change the |
|
|
1487 | watched path in your callback, you could call this fucntion to avoid |
|
|
1488 | detecting this change (while introducing a race condition). Can also be |
|
|
1489 | useful simply to find out the new values. |
|
|
1490 | |
|
|
1491 | =item ev_statdata attr [read-only] |
|
|
1492 | |
|
|
1493 | The most-recently detected attributes of the file. Although the type is of |
|
|
1494 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1495 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1496 | was some error while C<stat>ing the file. |
|
|
1497 | |
|
|
1498 | =item ev_statdata prev [read-only] |
|
|
1499 | |
|
|
1500 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1501 | C<prev> != C<attr>. |
|
|
1502 | |
|
|
1503 | =item ev_tstamp interval [read-only] |
|
|
1504 | |
|
|
1505 | The specified interval. |
|
|
1506 | |
|
|
1507 | =item const char *path [read-only] |
|
|
1508 | |
|
|
1509 | The filesystem path that is being watched. |
|
|
1510 | |
|
|
1511 | =back |
|
|
1512 | |
|
|
1513 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1514 | |
|
|
1515 | static void |
|
|
1516 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1517 | { |
|
|
1518 | /* /etc/passwd changed in some way */ |
|
|
1519 | if (w->attr.st_nlink) |
|
|
1520 | { |
|
|
1521 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1522 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1523 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1524 | } |
|
|
1525 | else |
|
|
1526 | /* you shalt not abuse printf for puts */ |
|
|
1527 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1528 | "if this is windows, they already arrived\n"); |
|
|
1529 | } |
|
|
1530 | |
|
|
1531 | ... |
|
|
1532 | ev_stat passwd; |
|
|
1533 | |
|
|
1534 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1535 | ev_stat_start (loop, &passwd); |
|
|
1536 | |
|
|
1537 | |
725 | =head2 C<ev_idle> - when you've got nothing better to do |
1538 | =head2 C<ev_idle> - when you've got nothing better to do... |
726 | |
1539 | |
727 | Idle watchers trigger events when there are no other events are pending |
1540 | Idle watchers trigger events when no other events of the same or higher |
728 | (prepare, check and other idle watchers do not count). That is, as long |
1541 | priority are pending (prepare, check and other idle watchers do not |
729 | as your process is busy handling sockets or timeouts (or even signals, |
1542 | count). |
730 | imagine) it will not be triggered. But when your process is idle all idle |
1543 | |
731 | watchers are being called again and again, once per event loop iteration - |
1544 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1545 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1546 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1547 | are pending), the idle watchers are being called once per event loop |
732 | until stopped, that is, or your process receives more events and becomes |
1548 | iteration - until stopped, that is, or your process receives more events |
733 | busy. |
1549 | and becomes busy again with higher priority stuff. |
734 | |
1550 | |
735 | The most noteworthy effect is that as long as any idle watchers are |
1551 | The most noteworthy effect is that as long as any idle watchers are |
736 | active, the process will not block when waiting for new events. |
1552 | active, the process will not block when waiting for new events. |
737 | |
1553 | |
738 | Apart from keeping your process non-blocking (which is a useful |
1554 | Apart from keeping your process non-blocking (which is a useful |
739 | effect on its own sometimes), idle watchers are a good place to do |
1555 | effect on its own sometimes), idle watchers are a good place to do |
740 | "pseudo-background processing", or delay processing stuff to after the |
1556 | "pseudo-background processing", or delay processing stuff to after the |
741 | event loop has handled all outstanding events. |
1557 | event loop has handled all outstanding events. |
742 | |
1558 | |
|
|
1559 | =head3 Watcher-Specific Functions and Data Members |
|
|
1560 | |
743 | =over 4 |
1561 | =over 4 |
744 | |
1562 | |
745 | =item ev_idle_init (ev_signal *, callback) |
1563 | =item ev_idle_init (ev_signal *, callback) |
746 | |
1564 | |
747 | Initialises and configures the idle watcher - it has no parameters of any |
1565 | Initialises and configures the idle watcher - it has no parameters of any |
748 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1566 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
749 | believe me. |
1567 | believe me. |
750 | |
1568 | |
751 | =back |
1569 | =back |
752 | |
1570 | |
|
|
1571 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
|
|
1572 | callback, free it. Also, use no error checking, as usual. |
|
|
1573 | |
|
|
1574 | static void |
|
|
1575 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1576 | { |
|
|
1577 | free (w); |
|
|
1578 | // now do something you wanted to do when the program has |
|
|
1579 | // no longer asnything immediate to do. |
|
|
1580 | } |
|
|
1581 | |
|
|
1582 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1583 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1584 | ev_idle_start (loop, idle_cb); |
|
|
1585 | |
|
|
1586 | |
753 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1587 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
754 | |
1588 | |
755 | Prepare and check watchers are usually (but not always) used in tandem: |
1589 | Prepare and check watchers are usually (but not always) used in tandem: |
756 | prepare watchers get invoked before the process blocks and check watchers |
1590 | prepare watchers get invoked before the process blocks and check watchers |
757 | afterwards. |
1591 | afterwards. |
758 | |
1592 | |
|
|
1593 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1594 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1595 | watchers. Other loops than the current one are fine, however. The |
|
|
1596 | rationale behind this is that you do not need to check for recursion in |
|
|
1597 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1598 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1599 | called in pairs bracketing the blocking call. |
|
|
1600 | |
759 | Their main purpose is to integrate other event mechanisms into libev. This |
1601 | Their main purpose is to integrate other event mechanisms into libev and |
760 | could be used, for example, to track variable changes, implement your own |
1602 | their use is somewhat advanced. This could be used, for example, to track |
761 | watchers, integrate net-snmp or a coroutine library and lots more. |
1603 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1604 | coroutine library and lots more. They are also occasionally useful if |
|
|
1605 | you cache some data and want to flush it before blocking (for example, |
|
|
1606 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1607 | watcher). |
762 | |
1608 | |
763 | This is done by examining in each prepare call which file descriptors need |
1609 | This is done by examining in each prepare call which file descriptors need |
764 | to be watched by the other library, registering C<ev_io> watchers for |
1610 | to be watched by the other library, registering C<ev_io> watchers for |
765 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1611 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
766 | provide just this functionality). Then, in the check watcher you check for |
1612 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
776 | with priority higher than or equal to the event loop and one coroutine |
1622 | with priority higher than or equal to the event loop and one coroutine |
777 | of lower priority, but only once, using idle watchers to keep the event |
1623 | of lower priority, but only once, using idle watchers to keep the event |
778 | loop from blocking if lower-priority coroutines are active, thus mapping |
1624 | loop from blocking if lower-priority coroutines are active, thus mapping |
779 | low-priority coroutines to idle/background tasks). |
1625 | low-priority coroutines to idle/background tasks). |
780 | |
1626 | |
|
|
1627 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1628 | priority, to ensure that they are being run before any other watchers |
|
|
1629 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1630 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1631 | supports this, they will be called before other C<ev_check> watchers |
|
|
1632 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1633 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1634 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1635 | coexist peacefully with others). |
|
|
1636 | |
|
|
1637 | =head3 Watcher-Specific Functions and Data Members |
|
|
1638 | |
781 | =over 4 |
1639 | =over 4 |
782 | |
1640 | |
783 | =item ev_prepare_init (ev_prepare *, callback) |
1641 | =item ev_prepare_init (ev_prepare *, callback) |
784 | |
1642 | |
785 | =item ev_check_init (ev_check *, callback) |
1643 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
787 | Initialises and configures the prepare or check watcher - they have no |
1645 | Initialises and configures the prepare or check watcher - they have no |
788 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1646 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
789 | macros, but using them is utterly, utterly and completely pointless. |
1647 | macros, but using them is utterly, utterly and completely pointless. |
790 | |
1648 | |
791 | =back |
1649 | =back |
|
|
1650 | |
|
|
1651 | There are a number of principal ways to embed other event loops or modules |
|
|
1652 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1653 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1654 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1655 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1656 | into the Glib event loop). |
|
|
1657 | |
|
|
1658 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
|
|
1659 | and in a check watcher, destroy them and call into libadns. What follows |
|
|
1660 | is pseudo-code only of course. This requires you to either use a low |
|
|
1661 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1662 | the callbacks for the IO/timeout watchers might not have been called yet. |
|
|
1663 | |
|
|
1664 | static ev_io iow [nfd]; |
|
|
1665 | static ev_timer tw; |
|
|
1666 | |
|
|
1667 | static void |
|
|
1668 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1669 | { |
|
|
1670 | } |
|
|
1671 | |
|
|
1672 | // create io watchers for each fd and a timer before blocking |
|
|
1673 | static void |
|
|
1674 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1675 | { |
|
|
1676 | int timeout = 3600000; |
|
|
1677 | struct pollfd fds [nfd]; |
|
|
1678 | // actual code will need to loop here and realloc etc. |
|
|
1679 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1680 | |
|
|
1681 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1682 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1683 | ev_timer_start (loop, &tw); |
|
|
1684 | |
|
|
1685 | // create one ev_io per pollfd |
|
|
1686 | for (int i = 0; i < nfd; ++i) |
|
|
1687 | { |
|
|
1688 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1689 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1690 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1691 | |
|
|
1692 | fds [i].revents = 0; |
|
|
1693 | ev_io_start (loop, iow + i); |
|
|
1694 | } |
|
|
1695 | } |
|
|
1696 | |
|
|
1697 | // stop all watchers after blocking |
|
|
1698 | static void |
|
|
1699 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1700 | { |
|
|
1701 | ev_timer_stop (loop, &tw); |
|
|
1702 | |
|
|
1703 | for (int i = 0; i < nfd; ++i) |
|
|
1704 | { |
|
|
1705 | // set the relevant poll flags |
|
|
1706 | // could also call adns_processreadable etc. here |
|
|
1707 | struct pollfd *fd = fds + i; |
|
|
1708 | int revents = ev_clear_pending (iow + i); |
|
|
1709 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1710 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1711 | |
|
|
1712 | // now stop the watcher |
|
|
1713 | ev_io_stop (loop, iow + i); |
|
|
1714 | } |
|
|
1715 | |
|
|
1716 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1717 | } |
|
|
1718 | |
|
|
1719 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1720 | in the prepare watcher and would dispose of the check watcher. |
|
|
1721 | |
|
|
1722 | Method 3: If the module to be embedded supports explicit event |
|
|
1723 | notification (adns does), you can also make use of the actual watcher |
|
|
1724 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1725 | |
|
|
1726 | static void |
|
|
1727 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1728 | { |
|
|
1729 | adns_state ads = (adns_state)w->data; |
|
|
1730 | update_now (EV_A); |
|
|
1731 | |
|
|
1732 | adns_processtimeouts (ads, &tv_now); |
|
|
1733 | } |
|
|
1734 | |
|
|
1735 | static void |
|
|
1736 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1737 | { |
|
|
1738 | adns_state ads = (adns_state)w->data; |
|
|
1739 | update_now (EV_A); |
|
|
1740 | |
|
|
1741 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1742 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1743 | } |
|
|
1744 | |
|
|
1745 | // do not ever call adns_afterpoll |
|
|
1746 | |
|
|
1747 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1748 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1749 | their poll function. The drawback with this solution is that the main |
|
|
1750 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1751 | this. |
|
|
1752 | |
|
|
1753 | static gint |
|
|
1754 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1755 | { |
|
|
1756 | int got_events = 0; |
|
|
1757 | |
|
|
1758 | for (n = 0; n < nfds; ++n) |
|
|
1759 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1760 | |
|
|
1761 | if (timeout >= 0) |
|
|
1762 | // create/start timer |
|
|
1763 | |
|
|
1764 | // poll |
|
|
1765 | ev_loop (EV_A_ 0); |
|
|
1766 | |
|
|
1767 | // stop timer again |
|
|
1768 | if (timeout >= 0) |
|
|
1769 | ev_timer_stop (EV_A_ &to); |
|
|
1770 | |
|
|
1771 | // stop io watchers again - their callbacks should have set |
|
|
1772 | for (n = 0; n < nfds; ++n) |
|
|
1773 | ev_io_stop (EV_A_ iow [n]); |
|
|
1774 | |
|
|
1775 | return got_events; |
|
|
1776 | } |
|
|
1777 | |
|
|
1778 | |
|
|
1779 | =head2 C<ev_embed> - when one backend isn't enough... |
|
|
1780 | |
|
|
1781 | This is a rather advanced watcher type that lets you embed one event loop |
|
|
1782 | into another (currently only C<ev_io> events are supported in the embedded |
|
|
1783 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1784 | fashion and must not be used). |
|
|
1785 | |
|
|
1786 | There are primarily two reasons you would want that: work around bugs and |
|
|
1787 | prioritise I/O. |
|
|
1788 | |
|
|
1789 | As an example for a bug workaround, the kqueue backend might only support |
|
|
1790 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1791 | still want to make use of it because you have many sockets and it scales |
|
|
1792 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1793 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1794 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1795 | at least you can use both at what they are best. |
|
|
1796 | |
|
|
1797 | As for prioritising I/O: rarely you have the case where some fds have |
|
|
1798 | to be watched and handled very quickly (with low latency), and even |
|
|
1799 | priorities and idle watchers might have too much overhead. In this case |
|
|
1800 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1801 | a second one, and embed the second one in the first. |
|
|
1802 | |
|
|
1803 | As long as the watcher is active, the callback will be invoked every time |
|
|
1804 | there might be events pending in the embedded loop. The callback must then |
|
|
1805 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
|
|
1806 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1807 | loop strictly lower priority for example). You can also set the callback |
|
|
1808 | to C<0>, in which case the embed watcher will automatically execute the |
|
|
1809 | embedded loop sweep. |
|
|
1810 | |
|
|
1811 | As long as the watcher is started it will automatically handle events. The |
|
|
1812 | callback will be invoked whenever some events have been handled. You can |
|
|
1813 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
1814 | interested in that. |
|
|
1815 | |
|
|
1816 | Also, there have not currently been made special provisions for forking: |
|
|
1817 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
|
|
1818 | but you will also have to stop and restart any C<ev_embed> watchers |
|
|
1819 | yourself. |
|
|
1820 | |
|
|
1821 | Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1822 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
|
|
1823 | portable one. |
|
|
1824 | |
|
|
1825 | So when you want to use this feature you will always have to be prepared |
|
|
1826 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1827 | this is to have a separate variables for your embeddable loop, try to |
|
|
1828 | create it, and if that fails, use the normal loop for everything: |
|
|
1829 | |
|
|
1830 | struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1831 | struct ev_loop *loop_lo = 0; |
|
|
1832 | struct ev_embed embed; |
|
|
1833 | |
|
|
1834 | // see if there is a chance of getting one that works |
|
|
1835 | // (remember that a flags value of 0 means autodetection) |
|
|
1836 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1837 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1838 | : 0; |
|
|
1839 | |
|
|
1840 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1841 | if (loop_lo) |
|
|
1842 | { |
|
|
1843 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1844 | ev_embed_start (loop_hi, &embed); |
|
|
1845 | } |
|
|
1846 | else |
|
|
1847 | loop_lo = loop_hi; |
|
|
1848 | |
|
|
1849 | =head3 Watcher-Specific Functions and Data Members |
|
|
1850 | |
|
|
1851 | =over 4 |
|
|
1852 | |
|
|
1853 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1854 | |
|
|
1855 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1856 | |
|
|
1857 | Configures the watcher to embed the given loop, which must be |
|
|
1858 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1859 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1860 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1861 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1862 | |
|
|
1863 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1864 | |
|
|
1865 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1866 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1867 | apropriate way for embedded loops. |
|
|
1868 | |
|
|
1869 | =item struct ev_loop *other [read-only] |
|
|
1870 | |
|
|
1871 | The embedded event loop. |
|
|
1872 | |
|
|
1873 | =back |
|
|
1874 | |
|
|
1875 | |
|
|
1876 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
1877 | |
|
|
1878 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
1879 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1880 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
1881 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
1882 | and only in the child after the fork. If whoever good citizen calling |
|
|
1883 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
1884 | handlers will be invoked, too, of course. |
|
|
1885 | |
|
|
1886 | =head3 Watcher-Specific Functions and Data Members |
|
|
1887 | |
|
|
1888 | =over 4 |
|
|
1889 | |
|
|
1890 | =item ev_fork_init (ev_signal *, callback) |
|
|
1891 | |
|
|
1892 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
1893 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
1894 | believe me. |
|
|
1895 | |
|
|
1896 | =back |
|
|
1897 | |
792 | |
1898 | |
793 | =head1 OTHER FUNCTIONS |
1899 | =head1 OTHER FUNCTIONS |
794 | |
1900 | |
795 | There are some other functions of possible interest. Described. Here. Now. |
1901 | There are some other functions of possible interest. Described. Here. Now. |
796 | |
1902 | |
… | |
… | |
826 | /* stdin might have data for us, joy! */; |
1932 | /* stdin might have data for us, joy! */; |
827 | } |
1933 | } |
828 | |
1934 | |
829 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1935 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
830 | |
1936 | |
831 | =item ev_feed_event (loop, watcher, int events) |
1937 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
832 | |
1938 | |
833 | Feeds the given event set into the event loop, as if the specified event |
1939 | Feeds the given event set into the event loop, as if the specified event |
834 | had happened for the specified watcher (which must be a pointer to an |
1940 | had happened for the specified watcher (which must be a pointer to an |
835 | initialised but not necessarily started event watcher). |
1941 | initialised but not necessarily started event watcher). |
836 | |
1942 | |
837 | =item ev_feed_fd_event (loop, int fd, int revents) |
1943 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
838 | |
1944 | |
839 | Feed an event on the given fd, as if a file descriptor backend detected |
1945 | Feed an event on the given fd, as if a file descriptor backend detected |
840 | the given events it. |
1946 | the given events it. |
841 | |
1947 | |
842 | =item ev_feed_signal_event (loop, int signum) |
1948 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
843 | |
1949 | |
844 | Feed an event as if the given signal occured (loop must be the default loop!). |
1950 | Feed an event as if the given signal occured (C<loop> must be the default |
|
|
1951 | loop!). |
845 | |
1952 | |
846 | =back |
1953 | =back |
|
|
1954 | |
847 | |
1955 | |
848 | =head1 LIBEVENT EMULATION |
1956 | =head1 LIBEVENT EMULATION |
849 | |
1957 | |
850 | Libev offers a compatibility emulation layer for libevent. It cannot |
1958 | Libev offers a compatibility emulation layer for libevent. It cannot |
851 | emulate the internals of libevent, so here are some usage hints: |
1959 | emulate the internals of libevent, so here are some usage hints: |
… | |
… | |
872 | |
1980 | |
873 | =back |
1981 | =back |
874 | |
1982 | |
875 | =head1 C++ SUPPORT |
1983 | =head1 C++ SUPPORT |
876 | |
1984 | |
877 | TBD. |
1985 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1986 | you to use some convinience methods to start/stop watchers and also change |
|
|
1987 | the callback model to a model using method callbacks on objects. |
|
|
1988 | |
|
|
1989 | To use it, |
|
|
1990 | |
|
|
1991 | #include <ev++.h> |
|
|
1992 | |
|
|
1993 | This automatically includes F<ev.h> and puts all of its definitions (many |
|
|
1994 | of them macros) into the global namespace. All C++ specific things are |
|
|
1995 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1996 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
|
|
1997 | |
|
|
1998 | Care has been taken to keep the overhead low. The only data member the C++ |
|
|
1999 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2000 | that the watcher is associated with (or no additional members at all if |
|
|
2001 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2002 | |
|
|
2003 | Currently, functions, and static and non-static member functions can be |
|
|
2004 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2005 | need one additional pointer for context. If you need support for other |
|
|
2006 | types of functors please contact the author (preferably after implementing |
|
|
2007 | it). |
|
|
2008 | |
|
|
2009 | Here is a list of things available in the C<ev> namespace: |
|
|
2010 | |
|
|
2011 | =over 4 |
|
|
2012 | |
|
|
2013 | =item C<ev::READ>, C<ev::WRITE> etc. |
|
|
2014 | |
|
|
2015 | These are just enum values with the same values as the C<EV_READ> etc. |
|
|
2016 | macros from F<ev.h>. |
|
|
2017 | |
|
|
2018 | =item C<ev::tstamp>, C<ev::now> |
|
|
2019 | |
|
|
2020 | Aliases to the same types/functions as with the C<ev_> prefix. |
|
|
2021 | |
|
|
2022 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
|
|
2023 | |
|
|
2024 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
|
|
2025 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
|
|
2026 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
|
|
2027 | defines by many implementations. |
|
|
2028 | |
|
|
2029 | All of those classes have these methods: |
|
|
2030 | |
|
|
2031 | =over 4 |
|
|
2032 | |
|
|
2033 | =item ev::TYPE::TYPE () |
|
|
2034 | |
|
|
2035 | =item ev::TYPE::TYPE (struct ev_loop *) |
|
|
2036 | |
|
|
2037 | =item ev::TYPE::~TYPE |
|
|
2038 | |
|
|
2039 | The constructor (optionally) takes an event loop to associate the watcher |
|
|
2040 | with. If it is omitted, it will use C<EV_DEFAULT>. |
|
|
2041 | |
|
|
2042 | The constructor calls C<ev_init> for you, which means you have to call the |
|
|
2043 | C<set> method before starting it. |
|
|
2044 | |
|
|
2045 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2046 | method to set a callback before you can start the watcher. |
|
|
2047 | |
|
|
2048 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2049 | not allow explicit template arguments for constructors). |
|
|
2050 | |
|
|
2051 | The destructor automatically stops the watcher if it is active. |
|
|
2052 | |
|
|
2053 | =item w->set<class, &class::method> (object *) |
|
|
2054 | |
|
|
2055 | This method sets the callback method to call. The method has to have a |
|
|
2056 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2057 | first argument and the C<revents> as second. The object must be given as |
|
|
2058 | parameter and is stored in the C<data> member of the watcher. |
|
|
2059 | |
|
|
2060 | This method synthesizes efficient thunking code to call your method from |
|
|
2061 | the C callback that libev requires. If your compiler can inline your |
|
|
2062 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2063 | your compiler is good :), then the method will be fully inlined into the |
|
|
2064 | thunking function, making it as fast as a direct C callback. |
|
|
2065 | |
|
|
2066 | Example: simple class declaration and watcher initialisation |
|
|
2067 | |
|
|
2068 | struct myclass |
|
|
2069 | { |
|
|
2070 | void io_cb (ev::io &w, int revents) { } |
|
|
2071 | } |
|
|
2072 | |
|
|
2073 | myclass obj; |
|
|
2074 | ev::io iow; |
|
|
2075 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2076 | |
|
|
2077 | =item w->set<function> (void *data = 0) |
|
|
2078 | |
|
|
2079 | Also sets a callback, but uses a static method or plain function as |
|
|
2080 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2081 | C<data> member and is free for you to use. |
|
|
2082 | |
|
|
2083 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2084 | |
|
|
2085 | See the method-C<set> above for more details. |
|
|
2086 | |
|
|
2087 | Example: |
|
|
2088 | |
|
|
2089 | static void io_cb (ev::io &w, int revents) { } |
|
|
2090 | iow.set <io_cb> (); |
|
|
2091 | |
|
|
2092 | =item w->set (struct ev_loop *) |
|
|
2093 | |
|
|
2094 | Associates a different C<struct ev_loop> with this watcher. You can only |
|
|
2095 | do this when the watcher is inactive (and not pending either). |
|
|
2096 | |
|
|
2097 | =item w->set ([args]) |
|
|
2098 | |
|
|
2099 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
|
|
2100 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
2101 | automatically stopped and restarted when reconfiguring it with this |
|
|
2102 | method. |
|
|
2103 | |
|
|
2104 | =item w->start () |
|
|
2105 | |
|
|
2106 | Starts the watcher. Note that there is no C<loop> argument, as the |
|
|
2107 | constructor already stores the event loop. |
|
|
2108 | |
|
|
2109 | =item w->stop () |
|
|
2110 | |
|
|
2111 | Stops the watcher if it is active. Again, no C<loop> argument. |
|
|
2112 | |
|
|
2113 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
|
|
2114 | |
|
|
2115 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
|
|
2116 | C<ev_TYPE_again> function. |
|
|
2117 | |
|
|
2118 | =item w->sweep () (C<ev::embed> only) |
|
|
2119 | |
|
|
2120 | Invokes C<ev_embed_sweep>. |
|
|
2121 | |
|
|
2122 | =item w->update () (C<ev::stat> only) |
|
|
2123 | |
|
|
2124 | Invokes C<ev_stat_stat>. |
|
|
2125 | |
|
|
2126 | =back |
|
|
2127 | |
|
|
2128 | =back |
|
|
2129 | |
|
|
2130 | Example: Define a class with an IO and idle watcher, start one of them in |
|
|
2131 | the constructor. |
|
|
2132 | |
|
|
2133 | class myclass |
|
|
2134 | { |
|
|
2135 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
2136 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
2137 | |
|
|
2138 | myclass (); |
|
|
2139 | } |
|
|
2140 | |
|
|
2141 | myclass::myclass (int fd) |
|
|
2142 | { |
|
|
2143 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2144 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2145 | |
|
|
2146 | io.start (fd, ev::READ); |
|
|
2147 | } |
|
|
2148 | |
|
|
2149 | |
|
|
2150 | =head1 MACRO MAGIC |
|
|
2151 | |
|
|
2152 | Libev can be compiled with a variety of options, the most fundamantal |
|
|
2153 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
|
|
2154 | functions and callbacks have an initial C<struct ev_loop *> argument. |
|
|
2155 | |
|
|
2156 | To make it easier to write programs that cope with either variant, the |
|
|
2157 | following macros are defined: |
|
|
2158 | |
|
|
2159 | =over 4 |
|
|
2160 | |
|
|
2161 | =item C<EV_A>, C<EV_A_> |
|
|
2162 | |
|
|
2163 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
2164 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
2165 | C<EV_A_> is used when other arguments are following. Example: |
|
|
2166 | |
|
|
2167 | ev_unref (EV_A); |
|
|
2168 | ev_timer_add (EV_A_ watcher); |
|
|
2169 | ev_loop (EV_A_ 0); |
|
|
2170 | |
|
|
2171 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
2172 | which is often provided by the following macro. |
|
|
2173 | |
|
|
2174 | =item C<EV_P>, C<EV_P_> |
|
|
2175 | |
|
|
2176 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
2177 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
2178 | C<EV_P_> is used when other parameters are following. Example: |
|
|
2179 | |
|
|
2180 | // this is how ev_unref is being declared |
|
|
2181 | static void ev_unref (EV_P); |
|
|
2182 | |
|
|
2183 | // this is how you can declare your typical callback |
|
|
2184 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
2185 | |
|
|
2186 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
2187 | suitable for use with C<EV_A>. |
|
|
2188 | |
|
|
2189 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
2190 | |
|
|
2191 | Similar to the other two macros, this gives you the value of the default |
|
|
2192 | loop, if multiple loops are supported ("ev loop default"). |
|
|
2193 | |
|
|
2194 | =back |
|
|
2195 | |
|
|
2196 | Example: Declare and initialise a check watcher, utilising the above |
|
|
2197 | macros so it will work regardless of whether multiple loops are supported |
|
|
2198 | or not. |
|
|
2199 | |
|
|
2200 | static void |
|
|
2201 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
2202 | { |
|
|
2203 | ev_check_stop (EV_A_ w); |
|
|
2204 | } |
|
|
2205 | |
|
|
2206 | ev_check check; |
|
|
2207 | ev_check_init (&check, check_cb); |
|
|
2208 | ev_check_start (EV_DEFAULT_ &check); |
|
|
2209 | ev_loop (EV_DEFAULT_ 0); |
|
|
2210 | |
|
|
2211 | =head1 EMBEDDING |
|
|
2212 | |
|
|
2213 | Libev can (and often is) directly embedded into host |
|
|
2214 | applications. Examples of applications that embed it include the Deliantra |
|
|
2215 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
2216 | and rxvt-unicode. |
|
|
2217 | |
|
|
2218 | The goal is to enable you to just copy the necessary files into your |
|
|
2219 | source directory without having to change even a single line in them, so |
|
|
2220 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
2221 | libev somewhere in your source tree). |
|
|
2222 | |
|
|
2223 | =head2 FILESETS |
|
|
2224 | |
|
|
2225 | Depending on what features you need you need to include one or more sets of files |
|
|
2226 | in your app. |
|
|
2227 | |
|
|
2228 | =head3 CORE EVENT LOOP |
|
|
2229 | |
|
|
2230 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
2231 | configuration (no autoconf): |
|
|
2232 | |
|
|
2233 | #define EV_STANDALONE 1 |
|
|
2234 | #include "ev.c" |
|
|
2235 | |
|
|
2236 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
2237 | single C source file only to provide the function implementations. To use |
|
|
2238 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
2239 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
2240 | where you can put other configuration options): |
|
|
2241 | |
|
|
2242 | #define EV_STANDALONE 1 |
|
|
2243 | #include "ev.h" |
|
|
2244 | |
|
|
2245 | Both header files and implementation files can be compiled with a C++ |
|
|
2246 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
2247 | as a bug). |
|
|
2248 | |
|
|
2249 | You need the following files in your source tree, or in a directory |
|
|
2250 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
2251 | |
|
|
2252 | ev.h |
|
|
2253 | ev.c |
|
|
2254 | ev_vars.h |
|
|
2255 | ev_wrap.h |
|
|
2256 | |
|
|
2257 | ev_win32.c required on win32 platforms only |
|
|
2258 | |
|
|
2259 | ev_select.c only when select backend is enabled (which is enabled by default) |
|
|
2260 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
2261 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
2262 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
2263 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
2264 | |
|
|
2265 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
2266 | to compile this single file. |
|
|
2267 | |
|
|
2268 | =head3 LIBEVENT COMPATIBILITY API |
|
|
2269 | |
|
|
2270 | To include the libevent compatibility API, also include: |
|
|
2271 | |
|
|
2272 | #include "event.c" |
|
|
2273 | |
|
|
2274 | in the file including F<ev.c>, and: |
|
|
2275 | |
|
|
2276 | #include "event.h" |
|
|
2277 | |
|
|
2278 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
2279 | |
|
|
2280 | You need the following additional files for this: |
|
|
2281 | |
|
|
2282 | event.h |
|
|
2283 | event.c |
|
|
2284 | |
|
|
2285 | =head3 AUTOCONF SUPPORT |
|
|
2286 | |
|
|
2287 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
2288 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
2289 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
|
|
2290 | include F<config.h> and configure itself accordingly. |
|
|
2291 | |
|
|
2292 | For this of course you need the m4 file: |
|
|
2293 | |
|
|
2294 | libev.m4 |
|
|
2295 | |
|
|
2296 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
2297 | |
|
|
2298 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
2299 | before including any of its files. The default is not to build for multiplicity |
|
|
2300 | and only include the select backend. |
|
|
2301 | |
|
|
2302 | =over 4 |
|
|
2303 | |
|
|
2304 | =item EV_STANDALONE |
|
|
2305 | |
|
|
2306 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
2307 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
2308 | implementations for some libevent functions (such as logging, which is not |
|
|
2309 | supported). It will also not define any of the structs usually found in |
|
|
2310 | F<event.h> that are not directly supported by the libev core alone. |
|
|
2311 | |
|
|
2312 | =item EV_USE_MONOTONIC |
|
|
2313 | |
|
|
2314 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
2315 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
2316 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
2317 | usually have to link against librt or something similar. Enabling it when |
|
|
2318 | the functionality isn't available is safe, though, although you have |
|
|
2319 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
2320 | function is hiding in (often F<-lrt>). |
|
|
2321 | |
|
|
2322 | =item EV_USE_REALTIME |
|
|
2323 | |
|
|
2324 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
2325 | realtime clock option at compiletime (and assume its availability at |
|
|
2326 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
2327 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
2328 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
|
|
2329 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2330 | |
|
|
2331 | =item EV_USE_NANOSLEEP |
|
|
2332 | |
|
|
2333 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2334 | and will use it for delays. Otherwise it will use C<select ()>. |
|
|
2335 | |
|
|
2336 | =item EV_USE_SELECT |
|
|
2337 | |
|
|
2338 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
2339 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
2340 | other method takes over, select will be it. Otherwise the select backend |
|
|
2341 | will not be compiled in. |
|
|
2342 | |
|
|
2343 | =item EV_SELECT_USE_FD_SET |
|
|
2344 | |
|
|
2345 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
2346 | structure. This is useful if libev doesn't compile due to a missing |
|
|
2347 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
2348 | exotic systems. This usually limits the range of file descriptors to some |
|
|
2349 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
2350 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
2351 | influence the size of the C<fd_set> used. |
|
|
2352 | |
|
|
2353 | =item EV_SELECT_IS_WINSOCKET |
|
|
2354 | |
|
|
2355 | When defined to C<1>, the select backend will assume that |
|
|
2356 | select/socket/connect etc. don't understand file descriptors but |
|
|
2357 | wants osf handles on win32 (this is the case when the select to |
|
|
2358 | be used is the winsock select). This means that it will call |
|
|
2359 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
2360 | it is assumed that all these functions actually work on fds, even |
|
|
2361 | on win32. Should not be defined on non-win32 platforms. |
|
|
2362 | |
|
|
2363 | =item EV_USE_POLL |
|
|
2364 | |
|
|
2365 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
2366 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
2367 | takes precedence over select. |
|
|
2368 | |
|
|
2369 | =item EV_USE_EPOLL |
|
|
2370 | |
|
|
2371 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
2372 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
2373 | otherwise another method will be used as fallback. This is the |
|
|
2374 | preferred backend for GNU/Linux systems. |
|
|
2375 | |
|
|
2376 | =item EV_USE_KQUEUE |
|
|
2377 | |
|
|
2378 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
2379 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
2380 | otherwise another method will be used as fallback. This is the preferred |
|
|
2381 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
2382 | supports some types of fds correctly (the only platform we found that |
|
|
2383 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
2384 | not be used unless explicitly requested. The best way to use it is to find |
|
|
2385 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
2386 | kqueue loop. |
|
|
2387 | |
|
|
2388 | =item EV_USE_PORT |
|
|
2389 | |
|
|
2390 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
2391 | 10 port style backend. Its availability will be detected at runtime, |
|
|
2392 | otherwise another method will be used as fallback. This is the preferred |
|
|
2393 | backend for Solaris 10 systems. |
|
|
2394 | |
|
|
2395 | =item EV_USE_DEVPOLL |
|
|
2396 | |
|
|
2397 | reserved for future expansion, works like the USE symbols above. |
|
|
2398 | |
|
|
2399 | =item EV_USE_INOTIFY |
|
|
2400 | |
|
|
2401 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2402 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2403 | be detected at runtime. |
|
|
2404 | |
|
|
2405 | =item EV_H |
|
|
2406 | |
|
|
2407 | The name of the F<ev.h> header file used to include it. The default if |
|
|
2408 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
|
|
2409 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
2410 | |
|
|
2411 | =item EV_CONFIG_H |
|
|
2412 | |
|
|
2413 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
2414 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
2415 | C<EV_H>, above. |
|
|
2416 | |
|
|
2417 | =item EV_EVENT_H |
|
|
2418 | |
|
|
2419 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
2420 | of how the F<event.h> header can be found. |
|
|
2421 | |
|
|
2422 | =item EV_PROTOTYPES |
|
|
2423 | |
|
|
2424 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
2425 | prototypes, but still define all the structs and other symbols. This is |
|
|
2426 | occasionally useful if you want to provide your own wrapper functions |
|
|
2427 | around libev functions. |
|
|
2428 | |
|
|
2429 | =item EV_MULTIPLICITY |
|
|
2430 | |
|
|
2431 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
2432 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
2433 | additional independent event loops. Otherwise there will be no support |
|
|
2434 | for multiple event loops and there is no first event loop pointer |
|
|
2435 | argument. Instead, all functions act on the single default loop. |
|
|
2436 | |
|
|
2437 | =item EV_MINPRI |
|
|
2438 | |
|
|
2439 | =item EV_MAXPRI |
|
|
2440 | |
|
|
2441 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2442 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2443 | provide for more priorities by overriding those symbols (usually defined |
|
|
2444 | to be C<-2> and C<2>, respectively). |
|
|
2445 | |
|
|
2446 | When doing priority-based operations, libev usually has to linearly search |
|
|
2447 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2448 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2449 | fine. |
|
|
2450 | |
|
|
2451 | If your embedding app does not need any priorities, defining these both to |
|
|
2452 | C<0> will save some memory and cpu. |
|
|
2453 | |
|
|
2454 | =item EV_PERIODIC_ENABLE |
|
|
2455 | |
|
|
2456 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2457 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2458 | code. |
|
|
2459 | |
|
|
2460 | =item EV_IDLE_ENABLE |
|
|
2461 | |
|
|
2462 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2463 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2464 | code. |
|
|
2465 | |
|
|
2466 | =item EV_EMBED_ENABLE |
|
|
2467 | |
|
|
2468 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2469 | defined to be C<0>, then they are not. |
|
|
2470 | |
|
|
2471 | =item EV_STAT_ENABLE |
|
|
2472 | |
|
|
2473 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2474 | defined to be C<0>, then they are not. |
|
|
2475 | |
|
|
2476 | =item EV_FORK_ENABLE |
|
|
2477 | |
|
|
2478 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2479 | defined to be C<0>, then they are not. |
|
|
2480 | |
|
|
2481 | =item EV_MINIMAL |
|
|
2482 | |
|
|
2483 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2484 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
2485 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2486 | |
|
|
2487 | =item EV_PID_HASHSIZE |
|
|
2488 | |
|
|
2489 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2490 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2491 | than enough. If you need to manage thousands of children you might want to |
|
|
2492 | increase this value (I<must> be a power of two). |
|
|
2493 | |
|
|
2494 | =item EV_INOTIFY_HASHSIZE |
|
|
2495 | |
|
|
2496 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2497 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2498 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2499 | watchers you might want to increase this value (I<must> be a power of |
|
|
2500 | two). |
|
|
2501 | |
|
|
2502 | =item EV_COMMON |
|
|
2503 | |
|
|
2504 | By default, all watchers have a C<void *data> member. By redefining |
|
|
2505 | this macro to a something else you can include more and other types of |
|
|
2506 | members. You have to define it each time you include one of the files, |
|
|
2507 | though, and it must be identical each time. |
|
|
2508 | |
|
|
2509 | For example, the perl EV module uses something like this: |
|
|
2510 | |
|
|
2511 | #define EV_COMMON \ |
|
|
2512 | SV *self; /* contains this struct */ \ |
|
|
2513 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2514 | |
|
|
2515 | =item EV_CB_DECLARE (type) |
|
|
2516 | |
|
|
2517 | =item EV_CB_INVOKE (watcher, revents) |
|
|
2518 | |
|
|
2519 | =item ev_set_cb (ev, cb) |
|
|
2520 | |
|
|
2521 | Can be used to change the callback member declaration in each watcher, |
|
|
2522 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2523 | definition and a statement, respectively. See the F<ev.h> header file for |
|
|
2524 | their default definitions. One possible use for overriding these is to |
|
|
2525 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
|
|
2526 | method calls instead of plain function calls in C++. |
|
|
2527 | |
|
|
2528 | =head2 EXPORTED API SYMBOLS |
|
|
2529 | |
|
|
2530 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2531 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2532 | all public symbols, one per line: |
|
|
2533 | |
|
|
2534 | Symbols.ev for libev proper |
|
|
2535 | Symbols.event for the libevent emulation |
|
|
2536 | |
|
|
2537 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2538 | multiple versions of libev linked together (which is obviously bad in |
|
|
2539 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2540 | |
|
|
2541 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2542 | include before including F<ev.h>: |
|
|
2543 | |
|
|
2544 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2545 | |
|
|
2546 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2547 | |
|
|
2548 | #define ev_backend myprefix_ev_backend |
|
|
2549 | #define ev_check_start myprefix_ev_check_start |
|
|
2550 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2551 | ... |
|
|
2552 | |
|
|
2553 | =head2 EXAMPLES |
|
|
2554 | |
|
|
2555 | For a real-world example of a program the includes libev |
|
|
2556 | verbatim, you can have a look at the EV perl module |
|
|
2557 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
2558 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
2559 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
2560 | will be compiled. It is pretty complex because it provides its own header |
|
|
2561 | file. |
|
|
2562 | |
|
|
2563 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
2564 | that everybody includes and which overrides some configure choices: |
|
|
2565 | |
|
|
2566 | #define EV_MINIMAL 1 |
|
|
2567 | #define EV_USE_POLL 0 |
|
|
2568 | #define EV_MULTIPLICITY 0 |
|
|
2569 | #define EV_PERIODIC_ENABLE 0 |
|
|
2570 | #define EV_STAT_ENABLE 0 |
|
|
2571 | #define EV_FORK_ENABLE 0 |
|
|
2572 | #define EV_CONFIG_H <config.h> |
|
|
2573 | #define EV_MINPRI 0 |
|
|
2574 | #define EV_MAXPRI 0 |
|
|
2575 | |
|
|
2576 | #include "ev++.h" |
|
|
2577 | |
|
|
2578 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
2579 | |
|
|
2580 | #include "ev_cpp.h" |
|
|
2581 | #include "ev.c" |
|
|
2582 | |
|
|
2583 | |
|
|
2584 | =head1 COMPLEXITIES |
|
|
2585 | |
|
|
2586 | In this section the complexities of (many of) the algorithms used inside |
|
|
2587 | libev will be explained. For complexity discussions about backends see the |
|
|
2588 | documentation for C<ev_default_init>. |
|
|
2589 | |
|
|
2590 | All of the following are about amortised time: If an array needs to be |
|
|
2591 | extended, libev needs to realloc and move the whole array, but this |
|
|
2592 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2593 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2594 | it is much faster and asymptotically approaches constant time. |
|
|
2595 | |
|
|
2596 | =over 4 |
|
|
2597 | |
|
|
2598 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
2599 | |
|
|
2600 | This means that, when you have a watcher that triggers in one hour and |
|
|
2601 | there are 100 watchers that would trigger before that then inserting will |
|
|
2602 | have to skip those 100 watchers. |
|
|
2603 | |
|
|
2604 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
2605 | |
|
|
2606 | That means that for changing a timer costs less than removing/adding them |
|
|
2607 | as only the relative motion in the event queue has to be paid for. |
|
|
2608 | |
|
|
2609 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
2610 | |
|
|
2611 | These just add the watcher into an array or at the head of a list. |
|
|
2612 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
2613 | |
|
|
2614 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
2615 | |
|
|
2616 | These watchers are stored in lists then need to be walked to find the |
|
|
2617 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2618 | have many watchers waiting for the same fd or signal). |
|
|
2619 | |
|
|
2620 | =item Finding the next timer per loop iteration: O(1) |
|
|
2621 | |
|
|
2622 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
2623 | |
|
|
2624 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2625 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2626 | |
|
|
2627 | =item Activating one watcher: O(1) |
|
|
2628 | |
|
|
2629 | =item Priority handling: O(number_of_priorities) |
|
|
2630 | |
|
|
2631 | Priorities are implemented by allocating some space for each |
|
|
2632 | priority. When doing priority-based operations, libev usually has to |
|
|
2633 | linearly search all the priorities. |
|
|
2634 | |
|
|
2635 | =back |
|
|
2636 | |
878 | |
2637 | |
879 | =head1 AUTHOR |
2638 | =head1 AUTHOR |
880 | |
2639 | |
881 | Marc Lehmann <libev@schmorp.de>. |
2640 | Marc Lehmann <libev@schmorp.de>. |
882 | |
2641 | |