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4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
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14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
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26 | <ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | </ul> |
28 | </ul> |
28 | </li> |
29 | </li> |
29 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> |
31 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
32 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
32 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> |
33 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> |
33 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
34 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
34 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
35 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
35 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
36 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
36 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
37 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
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38 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</a></li> |
37 | </ul> |
39 | </ul> |
38 | </li> |
40 | </li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
41 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
42 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
43 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
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96 | <div id="TIME_REPRESENTATION_CONTENT"> |
98 | <div id="TIME_REPRESENTATION_CONTENT"> |
97 | <p>Libev represents time as a single floating point number, representing the |
99 | <p>Libev represents time as a single floating point number, representing the |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
100 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | the beginning of 1970, details are complicated, don't ask). This type is |
101 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
102 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
101 | to the double type in C.</p> |
103 | to the <code>double</code> type in C, and when you need to do any calculations on |
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104 | it, you should treat it as such.</p> |
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105 | |
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106 | |
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107 | |
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108 | |
102 | |
109 | |
103 | </div> |
110 | </div> |
104 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
111 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
105 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
112 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
106 | <p>These functions can be called anytime, even before initialising the |
113 | <p>These functions can be called anytime, even before initialising the |
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122 | version of the library your program was compiled against.</p> |
129 | version of the library your program was compiled against.</p> |
123 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
130 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
124 | as this indicates an incompatible change. Minor versions are usually |
131 | as this indicates an incompatible change. Minor versions are usually |
125 | compatible to older versions, so a larger minor version alone is usually |
132 | compatible to older versions, so a larger minor version alone is usually |
126 | not a problem.</p> |
133 | not a problem.</p> |
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134 | <p>Example: make sure we haven't accidentally been linked against the wrong |
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135 | version:</p> |
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136 | <pre> assert (("libev version mismatch", |
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137 | ev_version_major () == EV_VERSION_MAJOR |
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138 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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139 | |
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140 | </pre> |
127 | </dd> |
141 | </dd> |
128 | <dt>unsigned int ev_supported_backends ()</dt> |
142 | <dt>unsigned int ev_supported_backends ()</dt> |
129 | <dd> |
143 | <dd> |
130 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
144 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
131 | value) compiled into this binary of libev (independent of their |
145 | value) compiled into this binary of libev (independent of their |
132 | availability on the system you are running on). See <code>ev_default_loop</code> for |
146 | availability on the system you are running on). See <code>ev_default_loop</code> for |
133 | a description of the set values.</p> |
147 | a description of the set values.</p> |
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148 | <p>Example: make sure we have the epoll method, because yeah this is cool and |
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149 | a must have and can we have a torrent of it please!!!11</p> |
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150 | <pre> assert (("sorry, no epoll, no sex", |
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151 | ev_supported_backends () & EVBACKEND_EPOLL)); |
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152 | |
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153 | </pre> |
134 | </dd> |
154 | </dd> |
135 | <dt>unsigned int ev_recommended_backends ()</dt> |
155 | <dt>unsigned int ev_recommended_backends ()</dt> |
136 | <dd> |
156 | <dd> |
137 | <p>Return the set of all backends compiled into this binary of libev and also |
157 | <p>Return the set of all backends compiled into this binary of libev and also |
138 | recommended for this platform. This set is often smaller than the one |
158 | recommended for this platform. This set is often smaller than the one |
139 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
159 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
140 | most BSDs and will not be autodetected unless you explicitly request it |
160 | most BSDs and will not be autodetected unless you explicitly request it |
141 | (assuming you know what you are doing). This is the set of backends that |
161 | (assuming you know what you are doing). This is the set of backends that |
142 | libev will probe for if you specify no backends explicitly.</p> |
162 | libev will probe for if you specify no backends explicitly.</p> |
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163 | </dd> |
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164 | <dt>unsigned int ev_embeddable_backends ()</dt> |
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165 | <dd> |
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166 | <p>Returns the set of backends that are embeddable in other event loops. This |
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167 | is the theoretical, all-platform, value. To find which backends |
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168 | might be supported on the current system, you would need to look at |
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169 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
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170 | recommended ones.</p> |
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171 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
143 | </dd> |
172 | </dd> |
144 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
173 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
145 | <dd> |
174 | <dd> |
146 | <p>Sets the allocation function to use (the prototype is similar to the |
175 | <p>Sets the allocation function to use (the prototype is similar to the |
147 | realloc C function, the semantics are identical). It is used to allocate |
176 | realloc C function, the semantics are identical). It is used to allocate |
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149 | needs to be allocated, the library might abort or take some potentially |
178 | needs to be allocated, the library might abort or take some potentially |
150 | destructive action. The default is your system realloc function.</p> |
179 | destructive action. The default is your system realloc function.</p> |
151 | <p>You could override this function in high-availability programs to, say, |
180 | <p>You could override this function in high-availability programs to, say, |
152 | free some memory if it cannot allocate memory, to use a special allocator, |
181 | free some memory if it cannot allocate memory, to use a special allocator, |
153 | or even to sleep a while and retry until some memory is available.</p> |
182 | or even to sleep a while and retry until some memory is available.</p> |
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183 | <p>Example: replace the libev allocator with one that waits a bit and then |
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184 | retries: better than mine).</p> |
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185 | <pre> static void * |
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186 | persistent_realloc (void *ptr, long size) |
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187 | { |
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188 | for (;;) |
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189 | { |
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190 | void *newptr = realloc (ptr, size); |
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191 | |
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192 | if (newptr) |
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193 | return newptr; |
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194 | |
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195 | sleep (60); |
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196 | } |
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197 | } |
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198 | |
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199 | ... |
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200 | ev_set_allocator (persistent_realloc); |
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201 | |
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202 | </pre> |
154 | </dd> |
203 | </dd> |
155 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
204 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
156 | <dd> |
205 | <dd> |
157 | <p>Set the callback function to call on a retryable syscall error (such |
206 | <p>Set the callback function to call on a retryable syscall error (such |
158 | as failed select, poll, epoll_wait). The message is a printable string |
207 | as failed select, poll, epoll_wait). The message is a printable string |
159 | indicating the system call or subsystem causing the problem. If this |
208 | indicating the system call or subsystem causing the problem. If this |
160 | callback is set, then libev will expect it to remedy the sitution, no |
209 | callback is set, then libev will expect it to remedy the sitution, no |
161 | matter what, when it returns. That is, libev will generally retry the |
210 | matter what, when it returns. That is, libev will generally retry the |
162 | requested operation, or, if the condition doesn't go away, do bad stuff |
211 | requested operation, or, if the condition doesn't go away, do bad stuff |
163 | (such as abort).</p> |
212 | (such as abort).</p> |
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213 | <p>Example: do the same thing as libev does internally:</p> |
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214 | <pre> static void |
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215 | fatal_error (const char *msg) |
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216 | { |
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217 | perror (msg); |
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218 | abort (); |
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219 | } |
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220 | |
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221 | ... |
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222 | ev_set_syserr_cb (fatal_error); |
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223 | |
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224 | </pre> |
164 | </dd> |
225 | </dd> |
165 | </dl> |
226 | </dl> |
166 | |
227 | |
167 | </div> |
228 | </div> |
168 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
229 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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293 | <dd> |
354 | <dd> |
294 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
355 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
295 | always distinct from the default loop. Unlike the default loop, it cannot |
356 | always distinct from the default loop. Unlike the default loop, it cannot |
296 | handle signal and child watchers, and attempts to do so will be greeted by |
357 | handle signal and child watchers, and attempts to do so will be greeted by |
297 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
358 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
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359 | <p>Example: try to create a event loop that uses epoll and nothing else.</p> |
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360 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
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361 | if (!epoller) |
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362 | fatal ("no epoll found here, maybe it hides under your chair"); |
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363 | |
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364 | </pre> |
298 | </dd> |
365 | </dd> |
299 | <dt>ev_default_destroy ()</dt> |
366 | <dt>ev_default_destroy ()</dt> |
300 | <dd> |
367 | <dd> |
301 | <p>Destroys the default loop again (frees all memory and kernel state |
368 | <p>Destroys the default loop again (frees all memory and kernel state |
302 | etc.). This stops all registered event watchers (by not touching them in |
369 | etc.). None of the active event watchers will be stopped in the normal |
303 | any way whatsoever, although you cannot rely on this :).</p> |
370 | sense, so e.g. <code>ev_is_active</code> might still return true. It is your |
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371 | responsibility to either stop all watchers cleanly yoursef <i>before</i> |
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372 | calling this function, or cope with the fact afterwards (which is usually |
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373 | the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them |
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374 | for example).</p> |
304 | </dd> |
375 | </dd> |
305 | <dt>ev_loop_destroy (loop)</dt> |
376 | <dt>ev_loop_destroy (loop)</dt> |
306 | <dd> |
377 | <dd> |
307 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
378 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
308 | earlier call to <code>ev_loop_new</code>.</p> |
379 | earlier call to <code>ev_loop_new</code>.</p> |
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338 | use.</p> |
409 | use.</p> |
339 | </dd> |
410 | </dd> |
340 | <dt>ev_tstamp ev_now (loop)</dt> |
411 | <dt>ev_tstamp ev_now (loop)</dt> |
341 | <dd> |
412 | <dd> |
342 | <p>Returns the current "event loop time", which is the time the event loop |
413 | <p>Returns the current "event loop time", which is the time the event loop |
343 | got events and started processing them. This timestamp does not change |
414 | received events and started processing them. This timestamp does not |
344 | as long as callbacks are being processed, and this is also the base time |
415 | change as long as callbacks are being processed, and this is also the base |
345 | used for relative timers. You can treat it as the timestamp of the event |
416 | time used for relative timers. You can treat it as the timestamp of the |
346 | occuring (or more correctly, the mainloop finding out about it).</p> |
417 | event occuring (or more correctly, libev finding out about it).</p> |
347 | </dd> |
418 | </dd> |
348 | <dt>ev_loop (loop, int flags)</dt> |
419 | <dt>ev_loop (loop, int flags)</dt> |
349 | <dd> |
420 | <dd> |
350 | <p>Finally, this is it, the event handler. This function usually is called |
421 | <p>Finally, this is it, the event handler. This function usually is called |
351 | after you initialised all your watchers and you want to start handling |
422 | after you initialised all your watchers and you want to start handling |
352 | events.</p> |
423 | events.</p> |
353 | <p>If the flags argument is specified as <code>0</code>, it will not return until |
424 | <p>If the flags argument is specified as <code>0</code>, it will not return until |
354 | either no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
425 | either no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
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426 | <p>Please note that an explicit <code>ev_unloop</code> is usually better than |
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427 | relying on all watchers to be stopped when deciding when a program has |
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428 | finished (especially in interactive programs), but having a program that |
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429 | automatically loops as long as it has to and no longer by virtue of |
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430 | relying on its watchers stopping correctly is a thing of beauty.</p> |
355 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
431 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
356 | those events and any outstanding ones, but will not block your process in |
432 | those events and any outstanding ones, but will not block your process in |
357 | case there are no events and will return after one iteration of the loop.</p> |
433 | case there are no events and will return after one iteration of the loop.</p> |
358 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
434 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
359 | neccessary) and will handle those and any outstanding ones. It will block |
435 | neccessary) and will handle those and any outstanding ones. It will block |
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381 | be handled here by queueing them when their watcher gets executed. |
457 | be handled here by queueing them when their watcher gets executed. |
382 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
458 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
383 | were used, return, otherwise continue with step *. |
459 | were used, return, otherwise continue with step *. |
384 | |
460 | |
385 | </pre> |
461 | </pre> |
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462 | <p>Example: queue some jobs and then loop until no events are outsanding |
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463 | anymore.</p> |
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464 | <pre> ... queue jobs here, make sure they register event watchers as long |
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465 | ... as they still have work to do (even an idle watcher will do..) |
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466 | ev_loop (my_loop, 0); |
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467 | ... jobs done. yeah! |
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468 | |
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469 | </pre> |
386 | </dd> |
470 | </dd> |
387 | <dt>ev_unloop (loop, how)</dt> |
471 | <dt>ev_unloop (loop, how)</dt> |
388 | <dd> |
472 | <dd> |
389 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
473 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
390 | has processed all outstanding events). The <code>how</code> argument must be either |
474 | has processed all outstanding events). The <code>how</code> argument must be either |
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402 | example, libev itself uses this for its internal signal pipe: It is not |
486 | example, libev itself uses this for its internal signal pipe: It is not |
403 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
487 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
404 | no event watchers registered by it are active. It is also an excellent |
488 | no event watchers registered by it are active. It is also an excellent |
405 | way to do this for generic recurring timers or from within third-party |
489 | way to do this for generic recurring timers or from within third-party |
406 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
490 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
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491 | <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> |
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492 | running when nothing else is active.</p> |
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493 | <pre> struct dv_signal exitsig; |
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494 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
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495 | ev_signal_start (myloop, &exitsig); |
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496 | evf_unref (myloop); |
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497 | |
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498 | </pre> |
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499 | <p>Example: for some weird reason, unregister the above signal handler again.</p> |
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500 | <pre> ev_ref (myloop); |
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501 | ev_signal_stop (myloop, &exitsig); |
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502 | |
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503 | </pre> |
407 | </dd> |
504 | </dd> |
408 | </dl> |
505 | </dl> |
409 | |
506 | |
410 | </div> |
507 | </div> |
411 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
508 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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443 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
540 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
444 | *)</code>), and you can stop watching for events at any time by calling the |
541 | *)</code>), and you can stop watching for events at any time by calling the |
445 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
542 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
446 | <p>As long as your watcher is active (has been started but not stopped) you |
543 | <p>As long as your watcher is active (has been started but not stopped) you |
447 | must not touch the values stored in it. Most specifically you must never |
544 | must not touch the values stored in it. Most specifically you must never |
448 | reinitialise it or call its set macro.</p> |
545 | reinitialise it or call its <code>set</code> macro.</p> |
449 | <p>You can check whether an event is active by calling the <code>ev_is_active |
|
|
450 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
|
|
451 | callback for it has not been called yet) you can use the <code>ev_is_pending |
|
|
452 | (watcher *)</code> macro.</p> |
|
|
453 | <p>Each and every callback receives the event loop pointer as first, the |
546 | <p>Each and every callback receives the event loop pointer as first, the |
454 | registered watcher structure as second, and a bitset of received events as |
547 | registered watcher structure as second, and a bitset of received events as |
455 | third argument.</p> |
548 | third argument.</p> |
456 | <p>The received events usually include a single bit per event type received |
549 | <p>The received events usually include a single bit per event type received |
457 | (you can receive multiple events at the same time). The possible bit masks |
550 | (you can receive multiple events at the same time). The possible bit masks |
… | |
… | |
506 | your callbacks is well-written it can just attempt the operation and cope |
599 | your callbacks is well-written it can just attempt the operation and cope |
507 | with the error from read() or write(). This will not work in multithreaded |
600 | with the error from read() or write(). This will not work in multithreaded |
508 | programs, though, so beware.</p> |
601 | programs, though, so beware.</p> |
509 | </dd> |
602 | </dd> |
510 | </dl> |
603 | </dl> |
|
|
604 | |
|
|
605 | </div> |
|
|
606 | <h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2> |
|
|
607 | <div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2"> |
|
|
608 | <p>In the following description, <code>TYPE</code> stands for the watcher type, |
|
|
609 | e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> |
|
|
610 | <dl> |
|
|
611 | <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> |
|
|
612 | <dd> |
|
|
613 | <p>This macro initialises the generic portion of a watcher. The contents |
|
|
614 | of the watcher object can be arbitrary (so <code>malloc</code> will do). Only |
|
|
615 | the generic parts of the watcher are initialised, you <i>need</i> to call |
|
|
616 | the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the |
|
|
617 | type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro |
|
|
618 | which rolls both calls into one.</p> |
|
|
619 | <p>You can reinitialise a watcher at any time as long as it has been stopped |
|
|
620 | (or never started) and there are no pending events outstanding.</p> |
|
|
621 | <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
622 | int revents)</code>.</p> |
|
|
623 | </dd> |
|
|
624 | <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> |
|
|
625 | <dd> |
|
|
626 | <p>This macro initialises the type-specific parts of a watcher. You need to |
|
|
627 | call <code>ev_init</code> at least once before you call this macro, but you can |
|
|
628 | call <code>ev_TYPE_set</code> any number of times. You must not, however, call this |
|
|
629 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
630 | difference to the <code>ev_init</code> macro).</p> |
|
|
631 | <p>Although some watcher types do not have type-specific arguments |
|
|
632 | (e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p> |
|
|
633 | </dd> |
|
|
634 | <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt> |
|
|
635 | <dd> |
|
|
636 | <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro |
|
|
637 | calls into a single call. This is the most convinient method to initialise |
|
|
638 | a watcher. The same limitations apply, of course.</p> |
|
|
639 | </dd> |
|
|
640 | <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
641 | <dd> |
|
|
642 | <p>Starts (activates) the given watcher. Only active watchers will receive |
|
|
643 | events. If the watcher is already active nothing will happen.</p> |
|
|
644 | </dd> |
|
|
645 | <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
646 | <dd> |
|
|
647 | <p>Stops the given watcher again (if active) and clears the pending |
|
|
648 | status. It is possible that stopped watchers are pending (for example, |
|
|
649 | non-repeating timers are being stopped when they become pending), but |
|
|
650 | <code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If |
|
|
651 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
652 | good idea to always call its <code>ev_TYPE_stop</code> function.</p> |
|
|
653 | </dd> |
|
|
654 | <dt>bool ev_is_active (ev_TYPE *watcher)</dt> |
|
|
655 | <dd> |
|
|
656 | <p>Returns a true value iff the watcher is active (i.e. it has been started |
|
|
657 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
658 | it.</p> |
|
|
659 | </dd> |
|
|
660 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
|
|
661 | <dd> |
|
|
662 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
663 | events but its callback has not yet been invoked). As long as a watcher |
|
|
664 | is pending (but not active) you must not call an init function on it (but |
|
|
665 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
|
|
666 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
|
|
667 | </dd> |
|
|
668 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
|
|
669 | <dd> |
|
|
670 | <p>Returns the callback currently set on the watcher.</p> |
|
|
671 | </dd> |
|
|
672 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
|
|
673 | <dd> |
|
|
674 | <p>Change the callback. You can change the callback at virtually any time |
|
|
675 | (modulo threads).</p> |
|
|
676 | </dd> |
|
|
677 | </dl> |
|
|
678 | |
|
|
679 | |
|
|
680 | |
|
|
681 | |
511 | |
682 | |
512 | </div> |
683 | </div> |
513 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
684 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
514 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
685 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
515 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
686 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
… | |
… | |
546 | </div> |
717 | </div> |
547 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
718 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
548 | <div id="WATCHER_TYPES_CONTENT"> |
719 | <div id="WATCHER_TYPES_CONTENT"> |
549 | <p>This section describes each watcher in detail, but will not repeat |
720 | <p>This section describes each watcher in detail, but will not repeat |
550 | information given in the last section.</p> |
721 | information given in the last section.</p> |
|
|
722 | |
|
|
723 | |
|
|
724 | |
|
|
725 | |
551 | |
726 | |
552 | </div> |
727 | </div> |
553 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
728 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
554 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
729 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
555 | <p>I/O watchers check whether a file descriptor is readable or writable |
730 | <p>I/O watchers check whether a file descriptor is readable or writable |
… | |
… | |
586 | when the readyness condition is no longer valid even when employing |
761 | when the readyness condition is no longer valid even when employing |
587 | typical ways of handling events, so its a good idea to use non-blocking |
762 | typical ways of handling events, so its a good idea to use non-blocking |
588 | I/O unconditionally.</p> |
763 | I/O unconditionally.</p> |
589 | </dd> |
764 | </dd> |
590 | </dl> |
765 | </dl> |
|
|
766 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
|
|
767 | readable, but only once. Since it is likely line-buffered, you could |
|
|
768 | attempt to read a whole line in the callback:</p> |
|
|
769 | <pre> static void |
|
|
770 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
771 | { |
|
|
772 | ev_io_stop (loop, w); |
|
|
773 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
774 | } |
|
|
775 | |
|
|
776 | ... |
|
|
777 | struct ev_loop *loop = ev_default_init (0); |
|
|
778 | struct ev_io stdin_readable; |
|
|
779 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
780 | ev_io_start (loop, &stdin_readable); |
|
|
781 | ev_loop (loop, 0); |
|
|
782 | |
|
|
783 | |
|
|
784 | |
|
|
785 | |
|
|
786 | </pre> |
591 | |
787 | |
592 | </div> |
788 | </div> |
593 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
789 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
594 | <div id="code_ev_timer_code_relative_and_opti-2"> |
790 | <div id="code_ev_timer_code_relative_and_opti-2"> |
595 | <p>Timer watchers are simple relative timers that generate an event after a |
791 | <p>Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
639 | time you successfully read or write some data. If you go into an idle |
835 | time you successfully read or write some data. If you go into an idle |
640 | state where you do not expect data to travel on the socket, you can stop |
836 | state where you do not expect data to travel on the socket, you can stop |
641 | the timer, and again will automatically restart it if need be.</p> |
837 | the timer, and again will automatically restart it if need be.</p> |
642 | </dd> |
838 | </dd> |
643 | </dl> |
839 | </dl> |
|
|
840 | <p>Example: create a timer that fires after 60 seconds.</p> |
|
|
841 | <pre> static void |
|
|
842 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
843 | { |
|
|
844 | .. one minute over, w is actually stopped right here |
|
|
845 | } |
|
|
846 | |
|
|
847 | struct ev_timer mytimer; |
|
|
848 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
849 | ev_timer_start (loop, &mytimer); |
|
|
850 | |
|
|
851 | </pre> |
|
|
852 | <p>Example: create a timeout timer that times out after 10 seconds of |
|
|
853 | inactivity.</p> |
|
|
854 | <pre> static void |
|
|
855 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
856 | { |
|
|
857 | .. ten seconds without any activity |
|
|
858 | } |
|
|
859 | |
|
|
860 | struct ev_timer mytimer; |
|
|
861 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
862 | ev_timer_again (&mytimer); /* start timer */ |
|
|
863 | ev_loop (loop, 0); |
|
|
864 | |
|
|
865 | // and in some piece of code that gets executed on any "activity": |
|
|
866 | // reset the timeout to start ticking again at 10 seconds |
|
|
867 | ev_timer_again (&mytimer); |
|
|
868 | |
|
|
869 | |
|
|
870 | |
|
|
871 | |
|
|
872 | </pre> |
644 | |
873 | |
645 | </div> |
874 | </div> |
646 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
875 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
647 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
876 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
648 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
877 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
649 | (and unfortunately a bit complex).</p> |
878 | (and unfortunately a bit complex).</p> |
650 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
879 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
651 | but on wallclock time (absolute time). You can tell a periodic watcher |
880 | but on wallclock time (absolute time). You can tell a periodic watcher |
652 | to trigger "at" some specific point in time. For example, if you tell a |
881 | to trigger "at" some specific point in time. For example, if you tell a |
653 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
882 | periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () |
654 | + 10.>) and then reset your system clock to the last year, then it will |
883 | + 10.</code>) and then reset your system clock to the last year, then it will |
655 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
884 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
656 | roughly 10 seconds later and of course not if you reset your system time |
885 | roughly 10 seconds later and of course not if you reset your system time |
657 | again).</p> |
886 | again).</p> |
658 | <p>They can also be used to implement vastly more complex timers, such as |
887 | <p>They can also be used to implement vastly more complex timers, such as |
659 | triggering an event on eahc midnight, local time.</p> |
888 | triggering an event on eahc midnight, local time.</p> |
… | |
… | |
732 | when you changed some parameters or the reschedule callback would return |
961 | when you changed some parameters or the reschedule callback would return |
733 | a different time than the last time it was called (e.g. in a crond like |
962 | a different time than the last time it was called (e.g. in a crond like |
734 | program when the crontabs have changed).</p> |
963 | program when the crontabs have changed).</p> |
735 | </dd> |
964 | </dd> |
736 | </dl> |
965 | </dl> |
|
|
966 | <p>Example: call a callback every hour, or, more precisely, whenever the |
|
|
967 | system clock is divisible by 3600. The callback invocation times have |
|
|
968 | potentially a lot of jittering, but good long-term stability.</p> |
|
|
969 | <pre> static void |
|
|
970 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
971 | { |
|
|
972 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
973 | } |
|
|
974 | |
|
|
975 | struct ev_periodic hourly_tick; |
|
|
976 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
977 | ev_periodic_start (loop, &hourly_tick); |
|
|
978 | |
|
|
979 | </pre> |
|
|
980 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
|
|
981 | <pre> #include <math.h> |
|
|
982 | |
|
|
983 | static ev_tstamp |
|
|
984 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
985 | { |
|
|
986 | return fmod (now, 3600.) + 3600.; |
|
|
987 | } |
|
|
988 | |
|
|
989 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
990 | |
|
|
991 | </pre> |
|
|
992 | <p>Example: call a callback every hour, starting now:</p> |
|
|
993 | <pre> struct ev_periodic hourly_tick; |
|
|
994 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
995 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
996 | ev_periodic_start (loop, &hourly_tick); |
|
|
997 | |
|
|
998 | |
|
|
999 | |
|
|
1000 | |
|
|
1001 | </pre> |
737 | |
1002 | |
738 | </div> |
1003 | </div> |
739 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
1004 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
740 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
1005 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
741 | <p>Signal watchers will trigger an event when the process receives a specific |
1006 | <p>Signal watchers will trigger an event when the process receives a specific |
… | |
… | |
755 | <p>Configures the watcher to trigger on the given signal number (usually one |
1020 | <p>Configures the watcher to trigger on the given signal number (usually one |
756 | of the <code>SIGxxx</code> constants).</p> |
1021 | of the <code>SIGxxx</code> constants).</p> |
757 | </dd> |
1022 | </dd> |
758 | </dl> |
1023 | </dl> |
759 | |
1024 | |
|
|
1025 | |
|
|
1026 | |
|
|
1027 | |
|
|
1028 | |
760 | </div> |
1029 | </div> |
761 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
1030 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
762 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
1031 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
763 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1032 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
764 | some child status changes (most typically when a child of yours dies).</p> |
1033 | some child status changes (most typically when a child of yours dies).</p> |
… | |
… | |
772 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1041 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
773 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1042 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
774 | process causing the status change.</p> |
1043 | process causing the status change.</p> |
775 | </dd> |
1044 | </dd> |
776 | </dl> |
1045 | </dl> |
|
|
1046 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
|
|
1047 | <pre> static void |
|
|
1048 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1049 | { |
|
|
1050 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1051 | } |
|
|
1052 | |
|
|
1053 | struct ev_signal signal_watcher; |
|
|
1054 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1055 | ev_signal_start (loop, &sigint_cb); |
|
|
1056 | |
|
|
1057 | |
|
|
1058 | |
|
|
1059 | |
|
|
1060 | </pre> |
777 | |
1061 | |
778 | </div> |
1062 | </div> |
779 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
1063 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
780 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1064 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
781 | <p>Idle watchers trigger events when there are no other events are pending |
1065 | <p>Idle watchers trigger events when there are no other events are pending |
… | |
… | |
797 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1081 | <p>Initialises and configures the idle watcher - it has no parameters of any |
798 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1082 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
799 | believe me.</p> |
1083 | believe me.</p> |
800 | </dd> |
1084 | </dd> |
801 | </dl> |
1085 | </dl> |
|
|
1086 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
|
|
1087 | callback, free it. Alos, use no error checking, as usual.</p> |
|
|
1088 | <pre> static void |
|
|
1089 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1090 | { |
|
|
1091 | free (w); |
|
|
1092 | // now do something you wanted to do when the program has |
|
|
1093 | // no longer asnything immediate to do. |
|
|
1094 | } |
|
|
1095 | |
|
|
1096 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1097 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1098 | ev_idle_start (loop, idle_cb); |
|
|
1099 | |
|
|
1100 | |
|
|
1101 | |
|
|
1102 | |
|
|
1103 | </pre> |
802 | |
1104 | |
803 | </div> |
1105 | </div> |
804 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
1106 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
805 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1107 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
806 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1108 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
807 | prepare watchers get invoked before the process blocks and check watchers |
1109 | prepare watchers get invoked before the process blocks and check watchers |
808 | afterwards.</p> |
1110 | afterwards.</p> |
809 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
1111 | <p>Their main purpose is to integrate other event mechanisms into libev and |
810 | could be used, for example, to track variable changes, implement your own |
1112 | their use is somewhat advanced. This could be used, for example, to track |
811 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
1113 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1114 | coroutine library and lots more.</p> |
812 | <p>This is done by examining in each prepare call which file descriptors need |
1115 | <p>This is done by examining in each prepare call which file descriptors need |
813 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1116 | to be watched by the other library, registering <code>ev_io</code> watchers for |
814 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1117 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
815 | provide just this functionality). Then, in the check watcher you check for |
1118 | provide just this functionality). Then, in the check watcher you check for |
816 | any events that occured (by checking the pending status of all watchers |
1119 | any events that occured (by checking the pending status of all watchers |
… | |
… | |
832 | <p>Initialises and configures the prepare or check watcher - they have no |
1135 | <p>Initialises and configures the prepare or check watcher - they have no |
833 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1136 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
834 | macros, but using them is utterly, utterly and completely pointless.</p> |
1137 | macros, but using them is utterly, utterly and completely pointless.</p> |
835 | </dd> |
1138 | </dd> |
836 | </dl> |
1139 | </dl> |
|
|
1140 | <p>Example: *TODO*.</p> |
|
|
1141 | |
|
|
1142 | |
|
|
1143 | |
|
|
1144 | |
|
|
1145 | |
|
|
1146 | </div> |
|
|
1147 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> |
|
|
1148 | <div id="code_ev_embed_code_when_one_backend_-2"> |
|
|
1149 | <p>This is a rather advanced watcher type that lets you embed one event loop |
|
|
1150 | into another (currently only <code>ev_io</code> events are supported in the embedded |
|
|
1151 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1152 | fashion and must not be used).</p> |
|
|
1153 | <p>There are primarily two reasons you would want that: work around bugs and |
|
|
1154 | prioritise I/O.</p> |
|
|
1155 | <p>As an example for a bug workaround, the kqueue backend might only support |
|
|
1156 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1157 | still want to make use of it because you have many sockets and it scales |
|
|
1158 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1159 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1160 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1161 | at least you can use both at what they are best.</p> |
|
|
1162 | <p>As for prioritising I/O: rarely you have the case where some fds have |
|
|
1163 | to be watched and handled very quickly (with low latency), and even |
|
|
1164 | priorities and idle watchers might have too much overhead. In this case |
|
|
1165 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1166 | a second one, and embed the second one in the first.</p> |
|
|
1167 | <p>As long as the watcher is active, the callback will be invoked every time |
|
|
1168 | there might be events pending in the embedded loop. The callback must then |
|
|
1169 | call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke |
|
|
1170 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1171 | loop strictly lower priority for example). You can also set the callback |
|
|
1172 | to <code>0</code>, in which case the embed watcher will automatically execute the |
|
|
1173 | embedded loop sweep.</p> |
|
|
1174 | <p>As long as the watcher is started it will automatically handle events. The |
|
|
1175 | callback will be invoked whenever some events have been handled. You can |
|
|
1176 | set the callback to <code>0</code> to avoid having to specify one if you are not |
|
|
1177 | interested in that.</p> |
|
|
1178 | <p>Also, there have not currently been made special provisions for forking: |
|
|
1179 | when you fork, you not only have to call <code>ev_loop_fork</code> on both loops, |
|
|
1180 | but you will also have to stop and restart any <code>ev_embed</code> watchers |
|
|
1181 | yourself.</p> |
|
|
1182 | <p>Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1183 | <code>ev_embeddable_backends</code> are, which, unfortunately, does not include any |
|
|
1184 | portable one.</p> |
|
|
1185 | <p>So when you want to use this feature you will always have to be prepared |
|
|
1186 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1187 | this is to have a separate variables for your embeddable loop, try to |
|
|
1188 | create it, and if that fails, use the normal loop for everything:</p> |
|
|
1189 | <pre> struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1190 | struct ev_loop *loop_lo = 0; |
|
|
1191 | struct ev_embed embed; |
|
|
1192 | |
|
|
1193 | // see if there is a chance of getting one that works |
|
|
1194 | // (remember that a flags value of 0 means autodetection) |
|
|
1195 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1196 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1197 | : 0; |
|
|
1198 | |
|
|
1199 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1200 | if (loop_lo) |
|
|
1201 | { |
|
|
1202 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1203 | ev_embed_start (loop_hi, &embed); |
|
|
1204 | } |
|
|
1205 | else |
|
|
1206 | loop_lo = loop_hi; |
|
|
1207 | |
|
|
1208 | </pre> |
|
|
1209 | <dl> |
|
|
1210 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1211 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1212 | <dd> |
|
|
1213 | <p>Configures the watcher to embed the given loop, which must be |
|
|
1214 | embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be |
|
|
1215 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1216 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1217 | if you do not want thta, you need to temporarily stop the embed watcher).</p> |
|
|
1218 | </dd> |
|
|
1219 | <dt>ev_embed_sweep (loop, ev_embed *)</dt> |
|
|
1220 | <dd> |
|
|
1221 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1222 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
|
|
1223 | apropriate way for embedded loops.</p> |
|
|
1224 | </dd> |
|
|
1225 | </dl> |
|
|
1226 | |
|
|
1227 | |
|
|
1228 | |
|
|
1229 | |
837 | |
1230 | |
838 | </div> |
1231 | </div> |
839 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1232 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
840 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1233 | <div id="OTHER_FUNCTIONS_CONTENT"> |
841 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1234 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
… | |
… | |
868 | |
1261 | |
869 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1262 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
870 | |
1263 | |
871 | </pre> |
1264 | </pre> |
872 | </dd> |
1265 | </dd> |
873 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
1266 | <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt> |
874 | <dd> |
1267 | <dd> |
875 | <p>Feeds the given event set into the event loop, as if the specified event |
1268 | <p>Feeds the given event set into the event loop, as if the specified event |
876 | had happened for the specified watcher (which must be a pointer to an |
1269 | had happened for the specified watcher (which must be a pointer to an |
877 | initialised but not necessarily started event watcher).</p> |
1270 | initialised but not necessarily started event watcher).</p> |
878 | </dd> |
1271 | </dd> |
879 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
1272 | <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt> |
880 | <dd> |
1273 | <dd> |
881 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
1274 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
882 | the given events it.</p> |
1275 | the given events it.</p> |
883 | </dd> |
1276 | </dd> |
884 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
1277 | <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt> |
885 | <dd> |
1278 | <dd> |
886 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
1279 | <p>Feed an event as if the given signal occured (<code>loop</code> must be the default |
|
|
1280 | loop!).</p> |
887 | </dd> |
1281 | </dd> |
888 | </dl> |
1282 | </dl> |
|
|
1283 | |
|
|
1284 | |
|
|
1285 | |
|
|
1286 | |
889 | |
1287 | |
890 | </div> |
1288 | </div> |
891 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1289 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
892 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1290 | <div id="LIBEVENT_EMULATION_CONTENT"> |
893 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1291 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
… | |
… | |
908 | </dl> |
1306 | </dl> |
909 | |
1307 | |
910 | </div> |
1308 | </div> |
911 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1309 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
912 | <div id="C_SUPPORT_CONTENT"> |
1310 | <div id="C_SUPPORT_CONTENT"> |
913 | <p>TBD.</p> |
1311 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1312 | you to use some convinience methods to start/stop watchers and also change |
|
|
1313 | the callback model to a model using method callbacks on objects.</p> |
|
|
1314 | <p>To use it,</p> |
|
|
1315 | <pre> #include <ev++.h> |
|
|
1316 | |
|
|
1317 | </pre> |
|
|
1318 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
|
|
1319 | and puts all of its definitions (many of them macros) into the global |
|
|
1320 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
|
|
1321 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
|
|
1322 | <code>EV_MULTIPLICITY</code>.</p> |
|
|
1323 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
|
|
1324 | <dl> |
|
|
1325 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
|
|
1326 | <dd> |
|
|
1327 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
|
|
1328 | macros from <cite>ev.h</cite>.</p> |
|
|
1329 | </dd> |
|
|
1330 | <dt><code>ev::tstamp</code>, <code>ev::now</code></dt> |
|
|
1331 | <dd> |
|
|
1332 | <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p> |
|
|
1333 | </dd> |
|
|
1334 | <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt> |
|
|
1335 | <dd> |
|
|
1336 | <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of |
|
|
1337 | the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code> |
|
|
1338 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
|
|
1339 | defines by many implementations.</p> |
|
|
1340 | <p>All of those classes have these methods:</p> |
|
|
1341 | <p> |
|
|
1342 | <dl> |
|
|
1343 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
|
|
1344 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
|
|
1345 | <dt>ev::TYPE::~TYPE</dt> |
|
|
1346 | <dd> |
|
|
1347 | <p>The constructor takes a pointer to an object and a method pointer to |
|
|
1348 | the event handler callback to call in this class. The constructor calls |
|
|
1349 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
|
|
1350 | before starting it. If you do not specify a loop then the constructor |
|
|
1351 | automatically associates the default loop with this watcher.</p> |
|
|
1352 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1353 | </dd> |
|
|
1354 | <dt>w->set (struct ev_loop *)</dt> |
|
|
1355 | <dd> |
|
|
1356 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
|
|
1357 | do this when the watcher is inactive (and not pending either).</p> |
|
|
1358 | </dd> |
|
|
1359 | <dt>w->set ([args])</dt> |
|
|
1360 | <dd> |
|
|
1361 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
|
|
1362 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1363 | automatically stopped and restarted.</p> |
|
|
1364 | </dd> |
|
|
1365 | <dt>w->start ()</dt> |
|
|
1366 | <dd> |
|
|
1367 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
|
|
1368 | constructor already takes the loop.</p> |
|
|
1369 | </dd> |
|
|
1370 | <dt>w->stop ()</dt> |
|
|
1371 | <dd> |
|
|
1372 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
|
|
1373 | </dd> |
|
|
1374 | <dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt> |
|
|
1375 | <dd> |
|
|
1376 | <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding |
|
|
1377 | <code>ev_TYPE_again</code> function.</p> |
|
|
1378 | </dd> |
|
|
1379 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
|
|
1380 | <dd> |
|
|
1381 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
|
|
1382 | </dd> |
|
|
1383 | </dl> |
|
|
1384 | </p> |
|
|
1385 | </dd> |
|
|
1386 | </dl> |
|
|
1387 | <p>Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1388 | the constructor.</p> |
|
|
1389 | <pre> class myclass |
|
|
1390 | { |
|
|
1391 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1392 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1393 | |
|
|
1394 | myclass (); |
|
|
1395 | } |
|
|
1396 | |
|
|
1397 | myclass::myclass (int fd) |
|
|
1398 | : io (this, &myclass::io_cb), |
|
|
1399 | idle (this, &myclass::idle_cb) |
|
|
1400 | { |
|
|
1401 | io.start (fd, ev::READ); |
|
|
1402 | } |
|
|
1403 | |
|
|
1404 | </pre> |
914 | |
1405 | |
915 | </div> |
1406 | </div> |
916 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1407 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
917 | <div id="AUTHOR_CONTENT"> |
1408 | <div id="AUTHOR_CONTENT"> |
918 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1409 | <p>Marc Lehmann <libev@schmorp.de>.</p> |