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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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9 | <meta name="created" content="Tue Nov 27 21:14:27 2007" /> |
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12 | <body> |
12 | <body> |
13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
15 | <h3 id="TOP">Index</h3> |
15 | <h3 id="TOP">Index</h3> |
16 | |
16 | |
17 | <ul><li><a href="#NAME">NAME</a></li> |
17 | <ul><li><a href="#NAME">NAME</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
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19 | <li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
24 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
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59 | <li><a href="#AUTHOR">AUTHOR</a> |
60 | <li><a href="#AUTHOR">AUTHOR</a> |
60 | </li> |
61 | </li> |
61 | </ul><hr /> |
62 | </ul><hr /> |
62 | <!-- INDEX END --> |
63 | <!-- INDEX END --> |
63 | |
64 | |
64 | <h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> |
65 | <h1 id="NAME">NAME</h1> |
65 | <div id="NAME_CONTENT"> |
66 | <div id="NAME_CONTENT"> |
66 | <p>libev - a high performance full-featured event loop written in C</p> |
67 | <p>libev - a high performance full-featured event loop written in C</p> |
67 | |
68 | |
68 | </div> |
69 | </div> |
69 | <h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
70 | <h1 id="SYNOPSIS">SYNOPSIS</h1> |
70 | <div id="SYNOPSIS_CONTENT"> |
71 | <div id="SYNOPSIS_CONTENT"> |
71 | <pre> /* this is the only header you need */ |
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72 | #include <ev.h> |
72 | <pre> #include <ev.h> |
73 | |
73 | |
74 | /* what follows is a fully working example program */ |
74 | </pre> |
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75 | |
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76 | </div> |
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77 | <h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1> |
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78 | <div id="EXAMPLE_PROGRAM_CONTENT"> |
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79 | <pre> #include <ev.h> |
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80 | |
75 | ev_io stdin_watcher; |
81 | ev_io stdin_watcher; |
76 | ev_timer timeout_watcher; |
82 | ev_timer timeout_watcher; |
77 | |
83 | |
78 | /* called when data readable on stdin */ |
84 | /* called when data readable on stdin */ |
79 | static void |
85 | static void |
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111 | } |
117 | } |
112 | |
118 | |
113 | </pre> |
119 | </pre> |
114 | |
120 | |
115 | </div> |
121 | </div> |
116 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
122 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
117 | <div id="DESCRIPTION_CONTENT"> |
123 | <div id="DESCRIPTION_CONTENT"> |
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124 | <p>The newest version of this document is also available as a html-formatted |
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125 | web page you might find easier to navigate when reading it for the first |
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126 | time: <a href="http://cvs.schmorp.de/libev/ev.html">http://cvs.schmorp.de/libev/ev.html</a>.</p> |
118 | <p>Libev is an event loop: you register interest in certain events (such as a |
127 | <p>Libev is an event loop: you register interest in certain events (such as a |
119 | file descriptor being readable or a timeout occuring), and it will manage |
128 | file descriptor being readable or a timeout occuring), and it will manage |
120 | these event sources and provide your program with events.</p> |
129 | these event sources and provide your program with events.</p> |
121 | <p>To do this, it must take more or less complete control over your process |
130 | <p>To do this, it must take more or less complete control over your process |
122 | (or thread) by executing the <i>event loop</i> handler, and will then |
131 | (or thread) by executing the <i>event loop</i> handler, and will then |
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125 | watchers</i>, which are relatively small C structures you initialise with the |
134 | watchers</i>, which are relatively small C structures you initialise with the |
126 | details of the event, and then hand it over to libev by <i>starting</i> the |
135 | details of the event, and then hand it over to libev by <i>starting</i> the |
127 | watcher.</p> |
136 | watcher.</p> |
128 | |
137 | |
129 | </div> |
138 | </div> |
130 | <h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
139 | <h1 id="FEATURES">FEATURES</h1> |
131 | <div id="FEATURES_CONTENT"> |
140 | <div id="FEATURES_CONTENT"> |
132 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
141 | <p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the |
133 | kqueue mechanisms for file descriptor events, relative timers, absolute |
142 | BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms |
134 | timers with customised rescheduling, signal events, process status change |
143 | for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface |
135 | events (related to SIGCHLD), and event watchers dealing with the event |
144 | (for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers |
136 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
145 | with customised rescheduling (<code>ev_periodic</code>), synchronous signals |
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146 | (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event |
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147 | watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
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148 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
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149 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
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150 | (<code>ev_fork</code>).</p> |
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151 | <p>It also is quite fast (see this |
137 | fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing |
152 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
138 | it to libevent for example).</p> |
153 | for example).</p> |
139 | |
154 | |
140 | </div> |
155 | </div> |
141 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
156 | <h1 id="CONVENTIONS">CONVENTIONS</h1> |
142 | <div id="CONVENTIONS_CONTENT"> |
157 | <div id="CONVENTIONS_CONTENT"> |
143 | <p>Libev is very configurable. In this manual the default configuration |
158 | <p>Libev is very configurable. In this manual the default configuration will |
144 | will be described, which supports multiple event loops. For more info |
159 | be described, which supports multiple event loops. For more info about |
145 | about various configuration options please have a look at the file |
160 | various configuration options please have a look at <strong>EMBED</strong> section in |
146 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
161 | this manual. If libev was configured without support for multiple event |
147 | support for multiple event loops, then all functions taking an initial |
162 | loops, then all functions taking an initial argument of name <code>loop</code> |
148 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
163 | (which is always of type <code>struct ev_loop *</code>) will not have this argument.</p> |
149 | will not have this argument.</p> |
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150 | |
164 | |
151 | </div> |
165 | </div> |
152 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
166 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1> |
153 | <div id="TIME_REPRESENTATION_CONTENT"> |
167 | <div id="TIME_REPRESENTATION_CONTENT"> |
154 | <p>Libev represents time as a single floating point number, representing the |
168 | <p>Libev represents time as a single floating point number, representing the |
155 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
169 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
156 | the beginning of 1970, details are complicated, don't ask). This type is |
170 | the beginning of 1970, details are complicated, don't ask). This type is |
157 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
171 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
158 | to the <code>double</code> type in C, and when you need to do any calculations on |
172 | to the <code>double</code> type in C, and when you need to do any calculations on |
159 | it, you should treat it as such.</p> |
173 | it, you should treat it as such.</p> |
160 | |
174 | |
161 | </div> |
175 | </div> |
162 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
176 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1> |
163 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
177 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
164 | <p>These functions can be called anytime, even before initialising the |
178 | <p>These functions can be called anytime, even before initialising the |
165 | library in any way.</p> |
179 | library in any way.</p> |
166 | <dl> |
180 | <dl> |
167 | <dt>ev_tstamp ev_time ()</dt> |
181 | <dt>ev_tstamp ev_time ()</dt> |
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180 | version of the library your program was compiled against.</p> |
194 | version of the library your program was compiled against.</p> |
181 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
195 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
182 | as this indicates an incompatible change. Minor versions are usually |
196 | as this indicates an incompatible change. Minor versions are usually |
183 | compatible to older versions, so a larger minor version alone is usually |
197 | compatible to older versions, so a larger minor version alone is usually |
184 | not a problem.</p> |
198 | not a problem.</p> |
185 | <p>Example: make sure we haven't accidentally been linked against the wrong |
199 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
186 | version:</p> |
200 | version.</p> |
187 | <pre> assert (("libev version mismatch", |
201 | <pre> assert (("libev version mismatch", |
188 | ev_version_major () == EV_VERSION_MAJOR |
202 | ev_version_major () == EV_VERSION_MAJOR |
189 | && ev_version_minor () >= EV_VERSION_MINOR)); |
203 | && ev_version_minor () >= EV_VERSION_MINOR)); |
190 | |
204 | |
191 | </pre> |
205 | </pre> |
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219 | might be supported on the current system, you would need to look at |
233 | might be supported on the current system, you would need to look at |
220 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
234 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
221 | recommended ones.</p> |
235 | recommended ones.</p> |
222 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
236 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
223 | </dd> |
237 | </dd> |
224 | <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt> |
238 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
225 | <dd> |
239 | <dd> |
226 | <p>Sets the allocation function to use (the prototype and semantics are |
240 | <p>Sets the allocation function to use (the prototype is similar - the |
227 | identical to the realloc C function). It is used to allocate and free |
241 | semantics is identical - to the realloc C function). It is used to |
228 | memory (no surprises here). If it returns zero when memory needs to be |
242 | allocate and free memory (no surprises here). If it returns zero when |
229 | allocated, the library might abort or take some potentially destructive |
243 | memory needs to be allocated, the library might abort or take some |
230 | action. The default is your system realloc function.</p> |
244 | potentially destructive action. The default is your system realloc |
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245 | function.</p> |
231 | <p>You could override this function in high-availability programs to, say, |
246 | <p>You could override this function in high-availability programs to, say, |
232 | free some memory if it cannot allocate memory, to use a special allocator, |
247 | free some memory if it cannot allocate memory, to use a special allocator, |
233 | or even to sleep a while and retry until some memory is available.</p> |
248 | or even to sleep a while and retry until some memory is available.</p> |
234 | <p>Example: replace the libev allocator with one that waits a bit and then |
249 | <p>Example: Replace the libev allocator with one that waits a bit and then |
235 | retries: better than mine).</p> |
250 | retries).</p> |
236 | <pre> static void * |
251 | <pre> static void * |
237 | persistent_realloc (void *ptr, size_t size) |
252 | persistent_realloc (void *ptr, size_t size) |
238 | { |
253 | { |
239 | for (;;) |
254 | for (;;) |
240 | { |
255 | { |
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259 | indicating the system call or subsystem causing the problem. If this |
274 | indicating the system call or subsystem causing the problem. If this |
260 | callback is set, then libev will expect it to remedy the sitution, no |
275 | callback is set, then libev will expect it to remedy the sitution, no |
261 | matter what, when it returns. That is, libev will generally retry the |
276 | matter what, when it returns. That is, libev will generally retry the |
262 | requested operation, or, if the condition doesn't go away, do bad stuff |
277 | requested operation, or, if the condition doesn't go away, do bad stuff |
263 | (such as abort).</p> |
278 | (such as abort).</p> |
264 | <p>Example: do the same thing as libev does internally:</p> |
279 | <p>Example: This is basically the same thing that libev does internally, too.</p> |
265 | <pre> static void |
280 | <pre> static void |
266 | fatal_error (const char *msg) |
281 | fatal_error (const char *msg) |
267 | { |
282 | { |
268 | perror (msg); |
283 | perror (msg); |
269 | abort (); |
284 | abort (); |
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275 | </pre> |
290 | </pre> |
276 | </dd> |
291 | </dd> |
277 | </dl> |
292 | </dl> |
278 | |
293 | |
279 | </div> |
294 | </div> |
280 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
295 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1> |
281 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
296 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
282 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
297 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
283 | types of such loops, the <i>default</i> loop, which supports signals and child |
298 | types of such loops, the <i>default</i> loop, which supports signals and child |
284 | events, and dynamically created loops which do not.</p> |
299 | events, and dynamically created loops which do not.</p> |
285 | <p>If you use threads, a common model is to run the default event loop |
300 | <p>If you use threads, a common model is to run the default event loop |
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314 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
329 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
315 | override the flags completely if it is found in the environment. This is |
330 | override the flags completely if it is found in the environment. This is |
316 | useful to try out specific backends to test their performance, or to work |
331 | useful to try out specific backends to test their performance, or to work |
317 | around bugs.</p> |
332 | around bugs.</p> |
318 | </dd> |
333 | </dd> |
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334 | <dt><code>EVFLAG_FORKCHECK</code></dt> |
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335 | <dd> |
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336 | <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after |
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337 | a fork, you can also make libev check for a fork in each iteration by |
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338 | enabling this flag.</p> |
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339 | <p>This works by calling <code>getpid ()</code> on every iteration of the loop, |
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340 | and thus this might slow down your event loop if you do a lot of loop |
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341 | iterations and little real work, but is usually not noticeable (on my |
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342 | Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence |
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343 | without a syscall and thus <i>very</i> fast, but my Linux system also has |
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344 | <code>pthread_atfork</code> which is even faster).</p> |
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345 | <p>The big advantage of this flag is that you can forget about fork (and |
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346 | forget about forgetting to tell libev about forking) when you use this |
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347 | flag.</p> |
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348 | <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code> |
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349 | environment variable.</p> |
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350 | </dd> |
319 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
351 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
320 | <dd> |
352 | <dd> |
321 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
353 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
322 | libev tries to roll its own fd_set with no limits on the number of fds, |
354 | libev tries to roll its own fd_set with no limits on the number of fds, |
323 | but if that fails, expect a fairly low limit on the number of fds when |
355 | but if that fails, expect a fairly low limit on the number of fds when |
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405 | <dd> |
437 | <dd> |
406 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
438 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
407 | always distinct from the default loop. Unlike the default loop, it cannot |
439 | always distinct from the default loop. Unlike the default loop, it cannot |
408 | handle signal and child watchers, and attempts to do so will be greeted by |
440 | handle signal and child watchers, and attempts to do so will be greeted by |
409 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
441 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
410 | <p>Example: try to create a event loop that uses epoll and nothing else.</p> |
442 | <p>Example: Try to create a event loop that uses epoll and nothing else.</p> |
411 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
443 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
412 | if (!epoller) |
444 | if (!epoller) |
413 | fatal ("no epoll found here, maybe it hides under your chair"); |
445 | fatal ("no epoll found here, maybe it hides under your chair"); |
414 | |
446 | |
415 | </pre> |
447 | </pre> |
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451 | <dt>ev_loop_fork (loop)</dt> |
483 | <dt>ev_loop_fork (loop)</dt> |
452 | <dd> |
484 | <dd> |
453 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
485 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
454 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
486 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
455 | after fork, and how you do this is entirely your own problem.</p> |
487 | after fork, and how you do this is entirely your own problem.</p> |
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488 | </dd> |
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489 | <dt>unsigned int ev_loop_count (loop)</dt> |
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490 | <dd> |
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491 | <p>Returns the count of loop iterations for the loop, which is identical to |
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492 | the number of times libev did poll for new events. It starts at <code>0</code> and |
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493 | happily wraps around with enough iterations.</p> |
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494 | <p>This value can sometimes be useful as a generation counter of sorts (it |
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495 | "ticks" the number of loop iterations), as it roughly corresponds with |
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496 | <code>ev_prepare</code> and <code>ev_check</code> calls.</p> |
456 | </dd> |
497 | </dd> |
457 | <dt>unsigned int ev_backend (loop)</dt> |
498 | <dt>unsigned int ev_backend (loop)</dt> |
458 | <dd> |
499 | <dd> |
459 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
500 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
460 | use.</p> |
501 | use.</p> |
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508 | be handled here by queueing them when their watcher gets executed. |
549 | be handled here by queueing them when their watcher gets executed. |
509 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
550 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
510 | were used, return, otherwise continue with step *. |
551 | were used, return, otherwise continue with step *. |
511 | |
552 | |
512 | </pre> |
553 | </pre> |
513 | <p>Example: queue some jobs and then loop until no events are outsanding |
554 | <p>Example: Queue some jobs and then loop until no events are outsanding |
514 | anymore.</p> |
555 | anymore.</p> |
515 | <pre> ... queue jobs here, make sure they register event watchers as long |
556 | <pre> ... queue jobs here, make sure they register event watchers as long |
516 | ... as they still have work to do (even an idle watcher will do..) |
557 | ... as they still have work to do (even an idle watcher will do..) |
517 | ev_loop (my_loop, 0); |
558 | ev_loop (my_loop, 0); |
518 | ... jobs done. yeah! |
559 | ... jobs done. yeah! |
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537 | example, libev itself uses this for its internal signal pipe: It is not |
578 | example, libev itself uses this for its internal signal pipe: It is not |
538 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
579 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
539 | no event watchers registered by it are active. It is also an excellent |
580 | no event watchers registered by it are active. It is also an excellent |
540 | way to do this for generic recurring timers or from within third-party |
581 | way to do this for generic recurring timers or from within third-party |
541 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
582 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
542 | <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> |
583 | <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code> |
543 | running when nothing else is active.</p> |
584 | running when nothing else is active.</p> |
544 | <pre> struct dv_signal exitsig; |
585 | <pre> struct ev_signal exitsig; |
545 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
586 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
546 | ev_signal_start (myloop, &exitsig); |
587 | ev_signal_start (loop, &exitsig); |
547 | evf_unref (myloop); |
588 | evf_unref (loop); |
548 | |
589 | |
549 | </pre> |
590 | </pre> |
550 | <p>Example: for some weird reason, unregister the above signal handler again.</p> |
591 | <p>Example: For some weird reason, unregister the above signal handler again.</p> |
551 | <pre> ev_ref (myloop); |
592 | <pre> ev_ref (loop); |
552 | ev_signal_stop (myloop, &exitsig); |
593 | ev_signal_stop (loop, &exitsig); |
553 | |
594 | |
554 | </pre> |
595 | </pre> |
555 | </dd> |
596 | </dd> |
556 | </dl> |
597 | </dl> |
557 | |
598 | |
558 | |
599 | |
559 | |
600 | |
560 | |
601 | |
561 | |
602 | |
562 | </div> |
603 | </div> |
563 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
604 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1> |
564 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
605 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
565 | <p>A watcher is a structure that you create and register to record your |
606 | <p>A watcher is a structure that you create and register to record your |
566 | interest in some event. For instance, if you want to wait for STDIN to |
607 | interest in some event. For instance, if you want to wait for STDIN to |
567 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
608 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
568 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
609 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
731 | events but its callback has not yet been invoked). As long as a watcher |
772 | events but its callback has not yet been invoked). As long as a watcher |
732 | is pending (but not active) you must not call an init function on it (but |
773 | is pending (but not active) you must not call an init function on it (but |
733 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
774 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
734 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
775 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
735 | </dd> |
776 | </dd> |
736 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
777 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
737 | <dd> |
778 | <dd> |
738 | <p>Returns the callback currently set on the watcher.</p> |
779 | <p>Returns the callback currently set on the watcher.</p> |
739 | </dd> |
780 | </dd> |
740 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
781 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
741 | <dd> |
782 | <dd> |
742 | <p>Change the callback. You can change the callback at virtually any time |
783 | <p>Change the callback. You can change the callback at virtually any time |
743 | (modulo threads).</p> |
784 | (modulo threads).</p> |
|
|
785 | </dd> |
|
|
786 | <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt> |
|
|
787 | <dt>int ev_priority (ev_TYPE *watcher)</dt> |
|
|
788 | <dd> |
|
|
789 | <p>Set and query the priority of the watcher. The priority is a small |
|
|
790 | integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code> |
|
|
791 | (default: <code>-2</code>). Pending watchers with higher priority will be invoked |
|
|
792 | before watchers with lower priority, but priority will not keep watchers |
|
|
793 | from being executed (except for <code>ev_idle</code> watchers).</p> |
|
|
794 | <p>This means that priorities are <i>only</i> used for ordering callback |
|
|
795 | invocation after new events have been received. This is useful, for |
|
|
796 | example, to reduce latency after idling, or more often, to bind two |
|
|
797 | watchers on the same event and make sure one is called first.</p> |
|
|
798 | <p>If you need to suppress invocation when higher priority events are pending |
|
|
799 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
|
|
800 | <p>The default priority used by watchers when no priority has been set is |
|
|
801 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
|
|
802 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
|
|
803 | fine, as long as you do not mind that the priority value you query might |
|
|
804 | or might not have been adjusted to be within valid range.</p> |
744 | </dd> |
805 | </dd> |
745 | </dl> |
806 | </dl> |
746 | |
807 | |
747 | |
808 | |
748 | |
809 | |
… | |
… | |
773 | struct my_io *w = (struct my_io *)w_; |
834 | struct my_io *w = (struct my_io *)w_; |
774 | ... |
835 | ... |
775 | } |
836 | } |
776 | |
837 | |
777 | </pre> |
838 | </pre> |
778 | <p>More interesting and less C-conformant ways of catsing your callback type |
839 | <p>More interesting and less C-conformant ways of casting your callback type |
779 | have been omitted....</p> |
840 | instead have been omitted.</p> |
|
|
841 | <p>Another common scenario is having some data structure with multiple |
|
|
842 | watchers:</p> |
|
|
843 | <pre> struct my_biggy |
|
|
844 | { |
|
|
845 | int some_data; |
|
|
846 | ev_timer t1; |
|
|
847 | ev_timer t2; |
|
|
848 | } |
780 | |
849 | |
|
|
850 | </pre> |
|
|
851 | <p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated, |
|
|
852 | you need to use <code>offsetof</code>:</p> |
|
|
853 | <pre> #include <stddef.h> |
781 | |
854 | |
|
|
855 | static void |
|
|
856 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
857 | { |
|
|
858 | struct my_biggy big = (struct my_biggy * |
|
|
859 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
860 | } |
782 | |
861 | |
|
|
862 | static void |
|
|
863 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
864 | { |
|
|
865 | struct my_biggy big = (struct my_biggy * |
|
|
866 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
867 | } |
783 | |
868 | |
784 | |
869 | |
|
|
870 | |
|
|
871 | |
|
|
872 | </pre> |
|
|
873 | |
785 | </div> |
874 | </div> |
786 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
875 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
787 | <div id="WATCHER_TYPES_CONTENT"> |
876 | <div id="WATCHER_TYPES_CONTENT"> |
788 | <p>This section describes each watcher in detail, but will not repeat |
877 | <p>This section describes each watcher in detail, but will not repeat |
789 | information given in the last section. Any initialisation/set macros, |
878 | information given in the last section. Any initialisation/set macros, |
790 | functions and members specific to the watcher type are explained.</p> |
879 | functions and members specific to the watcher type are explained.</p> |
791 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
880 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
… | |
… | |
831 | this situation even with a relatively standard program structure. Thus |
920 | this situation even with a relatively standard program structure. Thus |
832 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
921 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
833 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
922 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
834 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
923 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
835 | play around with an Xlib connection), then you have to seperately re-test |
924 | play around with an Xlib connection), then you have to seperately re-test |
836 | wether a file descriptor is really ready with a known-to-be good interface |
925 | whether a file descriptor is really ready with a known-to-be good interface |
837 | such as poll (fortunately in our Xlib example, Xlib already does this on |
926 | such as poll (fortunately in our Xlib example, Xlib already does this on |
838 | its own, so its quite safe to use).</p> |
927 | its own, so its quite safe to use).</p> |
839 | <dl> |
928 | <dl> |
840 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
929 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
841 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
930 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
… | |
… | |
851 | <dt>int events [read-only]</dt> |
940 | <dt>int events [read-only]</dt> |
852 | <dd> |
941 | <dd> |
853 | <p>The events being watched.</p> |
942 | <p>The events being watched.</p> |
854 | </dd> |
943 | </dd> |
855 | </dl> |
944 | </dl> |
856 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
945 | <p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
857 | readable, but only once. Since it is likely line-buffered, you could |
946 | readable, but only once. Since it is likely line-buffered, you could |
858 | attempt to read a whole line in the callback:</p> |
947 | attempt to read a whole line in the callback.</p> |
859 | <pre> static void |
948 | <pre> static void |
860 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
949 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
861 | { |
950 | { |
862 | ev_io_stop (loop, w); |
951 | ev_io_stop (loop, w); |
863 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
952 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
… | |
… | |
912 | </dd> |
1001 | </dd> |
913 | <dt>ev_timer_again (loop)</dt> |
1002 | <dt>ev_timer_again (loop)</dt> |
914 | <dd> |
1003 | <dd> |
915 | <p>This will act as if the timer timed out and restart it again if it is |
1004 | <p>This will act as if the timer timed out and restart it again if it is |
916 | repeating. The exact semantics are:</p> |
1005 | repeating. The exact semantics are:</p> |
|
|
1006 | <p>If the timer is pending, its pending status is cleared.</p> |
917 | <p>If the timer is started but nonrepeating, stop it.</p> |
1007 | <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p> |
918 | <p>If the timer is repeating, either start it if necessary (with the repeat |
1008 | <p>If the timer is repeating, either start it if necessary (with the |
919 | value), or reset the running timer to the repeat value.</p> |
1009 | <code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p> |
920 | <p>This sounds a bit complicated, but here is a useful and typical |
1010 | <p>This sounds a bit complicated, but here is a useful and typical |
921 | example: Imagine you have a tcp connection and you want a so-called |
1011 | example: Imagine you have a tcp connection and you want a so-called idle |
922 | idle timeout, that is, you want to be called when there have been, |
1012 | timeout, that is, you want to be called when there have been, say, 60 |
923 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1013 | seconds of inactivity on the socket. The easiest way to do this is to |
924 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
1014 | configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call |
925 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
1015 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
926 | you go into an idle state where you do not expect data to travel on the |
1016 | you go into an idle state where you do not expect data to travel on the |
927 | socket, you can stop the timer, and again will automatically restart it if |
1017 | socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will |
928 | need be.</p> |
1018 | automatically restart it if need be.</p> |
929 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
1019 | <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code> |
930 | and only ever use the <code>repeat</code> value:</p> |
1020 | altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p> |
931 | <pre> ev_timer_init (timer, callback, 0., 5.); |
1021 | <pre> ev_timer_init (timer, callback, 0., 5.); |
932 | ev_timer_again (loop, timer); |
1022 | ev_timer_again (loop, timer); |
933 | ... |
1023 | ... |
934 | timer->again = 17.; |
1024 | timer->again = 17.; |
935 | ev_timer_again (loop, timer); |
1025 | ev_timer_again (loop, timer); |
936 | ... |
1026 | ... |
937 | timer->again = 10.; |
1027 | timer->again = 10.; |
938 | ev_timer_again (loop, timer); |
1028 | ev_timer_again (loop, timer); |
939 | |
1029 | |
940 | </pre> |
1030 | </pre> |
941 | <p>This is more efficient then stopping/starting the timer eahc time you want |
1031 | <p>This is more slightly efficient then stopping/starting the timer each time |
942 | to modify its timeout value.</p> |
1032 | you want to modify its timeout value.</p> |
943 | </dd> |
1033 | </dd> |
944 | <dt>ev_tstamp repeat [read-write]</dt> |
1034 | <dt>ev_tstamp repeat [read-write]</dt> |
945 | <dd> |
1035 | <dd> |
946 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
1036 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
947 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
1037 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
948 | which is also when any modifications are taken into account.</p> |
1038 | which is also when any modifications are taken into account.</p> |
949 | </dd> |
1039 | </dd> |
950 | </dl> |
1040 | </dl> |
951 | <p>Example: create a timer that fires after 60 seconds.</p> |
1041 | <p>Example: Create a timer that fires after 60 seconds.</p> |
952 | <pre> static void |
1042 | <pre> static void |
953 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1043 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
954 | { |
1044 | { |
955 | .. one minute over, w is actually stopped right here |
1045 | .. one minute over, w is actually stopped right here |
956 | } |
1046 | } |
… | |
… | |
958 | struct ev_timer mytimer; |
1048 | struct ev_timer mytimer; |
959 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1049 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
960 | ev_timer_start (loop, &mytimer); |
1050 | ev_timer_start (loop, &mytimer); |
961 | |
1051 | |
962 | </pre> |
1052 | </pre> |
963 | <p>Example: create a timeout timer that times out after 10 seconds of |
1053 | <p>Example: Create a timeout timer that times out after 10 seconds of |
964 | inactivity.</p> |
1054 | inactivity.</p> |
965 | <pre> static void |
1055 | <pre> static void |
966 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1056 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
967 | { |
1057 | { |
968 | .. ten seconds without any activity |
1058 | .. ten seconds without any activity |
… | |
… | |
1084 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
1174 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
1085 | switched off. Can be changed any time, but changes only take effect when |
1175 | switched off. Can be changed any time, but changes only take effect when |
1086 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
1176 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
1087 | </dd> |
1177 | </dd> |
1088 | </dl> |
1178 | </dl> |
1089 | <p>Example: call a callback every hour, or, more precisely, whenever the |
1179 | <p>Example: Call a callback every hour, or, more precisely, whenever the |
1090 | system clock is divisible by 3600. The callback invocation times have |
1180 | system clock is divisible by 3600. The callback invocation times have |
1091 | potentially a lot of jittering, but good long-term stability.</p> |
1181 | potentially a lot of jittering, but good long-term stability.</p> |
1092 | <pre> static void |
1182 | <pre> static void |
1093 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1183 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1094 | { |
1184 | { |
… | |
… | |
1098 | struct ev_periodic hourly_tick; |
1188 | struct ev_periodic hourly_tick; |
1099 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1189 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1100 | ev_periodic_start (loop, &hourly_tick); |
1190 | ev_periodic_start (loop, &hourly_tick); |
1101 | |
1191 | |
1102 | </pre> |
1192 | </pre> |
1103 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
1193 | <p>Example: The same as above, but use a reschedule callback to do it:</p> |
1104 | <pre> #include <math.h> |
1194 | <pre> #include <math.h> |
1105 | |
1195 | |
1106 | static ev_tstamp |
1196 | static ev_tstamp |
1107 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1197 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1108 | { |
1198 | { |
… | |
… | |
1110 | } |
1200 | } |
1111 | |
1201 | |
1112 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1202 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1113 | |
1203 | |
1114 | </pre> |
1204 | </pre> |
1115 | <p>Example: call a callback every hour, starting now:</p> |
1205 | <p>Example: Call a callback every hour, starting now:</p> |
1116 | <pre> struct ev_periodic hourly_tick; |
1206 | <pre> struct ev_periodic hourly_tick; |
1117 | ev_periodic_init (&hourly_tick, clock_cb, |
1207 | ev_periodic_init (&hourly_tick, clock_cb, |
1118 | fmod (ev_now (loop), 3600.), 3600., 0); |
1208 | fmod (ev_now (loop), 3600.), 3600., 0); |
1119 | ev_periodic_start (loop, &hourly_tick); |
1209 | ev_periodic_start (loop, &hourly_tick); |
1120 | |
1210 | |
… | |
… | |
1181 | <dd> |
1271 | <dd> |
1182 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
1272 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
1183 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
1273 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
1184 | </dd> |
1274 | </dd> |
1185 | </dl> |
1275 | </dl> |
1186 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
1276 | <p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p> |
1187 | <pre> static void |
1277 | <pre> static void |
1188 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1278 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1189 | { |
1279 | { |
1190 | ev_unloop (loop, EVUNLOOP_ALL); |
1280 | ev_unloop (loop, EVUNLOOP_ALL); |
1191 | } |
1281 | } |
… | |
… | |
1208 | <p>The path does not need to exist: changing from "path exists" to "path does |
1298 | <p>The path does not need to exist: changing from "path exists" to "path does |
1209 | not exist" is a status change like any other. The condition "path does |
1299 | not exist" is a status change like any other. The condition "path does |
1210 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1300 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1211 | otherwise always forced to be at least one) and all the other fields of |
1301 | otherwise always forced to be at least one) and all the other fields of |
1212 | the stat buffer having unspecified contents.</p> |
1302 | the stat buffer having unspecified contents.</p> |
|
|
1303 | <p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is |
|
|
1304 | relative and your working directory changes, the behaviour is undefined.</p> |
1213 | <p>Since there is no standard to do this, the portable implementation simply |
1305 | <p>Since there is no standard to do this, the portable implementation simply |
1214 | calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You |
1306 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
1215 | can specify a recommended polling interval for this case. If you specify |
1307 | can specify a recommended polling interval for this case. If you specify |
1216 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1308 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1217 | unspecified default</i> value will be used (which you can expect to be around |
1309 | unspecified default</i> value will be used (which you can expect to be around |
1218 | five seconds, although this might change dynamically). Libev will also |
1310 | five seconds, although this might change dynamically). Libev will also |
1219 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
1311 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
1220 | usually overkill.</p> |
1312 | usually overkill.</p> |
1221 | <p>This watcher type is not meant for massive numbers of stat watchers, |
1313 | <p>This watcher type is not meant for massive numbers of stat watchers, |
1222 | as even with OS-supported change notifications, this can be |
1314 | as even with OS-supported change notifications, this can be |
1223 | resource-intensive.</p> |
1315 | resource-intensive.</p> |
1224 | <p>At the time of this writing, no specific OS backends are implemented, but |
1316 | <p>At the time of this writing, only the Linux inotify interface is |
1225 | if demand increases, at least a kqueue and inotify backend will be added.</p> |
1317 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1318 | reader). Inotify will be used to give hints only and should not change the |
|
|
1319 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
|
|
1320 | to fall back to regular polling again even with inotify, but changes are |
|
|
1321 | usually detected immediately, and if the file exists there will be no |
|
|
1322 | polling.</p> |
1226 | <dl> |
1323 | <dl> |
1227 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1324 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1228 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1325 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1229 | <dd> |
1326 | <dd> |
1230 | <p>Configures the watcher to wait for status changes of the given |
1327 | <p>Configures the watcher to wait for status changes of the given |
… | |
… | |
1293 | </pre> |
1390 | </pre> |
1294 | |
1391 | |
1295 | </div> |
1392 | </div> |
1296 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1393 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1297 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1394 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1298 | <p>Idle watchers trigger events when there are no other events are pending |
1395 | <p>Idle watchers trigger events when no other events of the same or higher |
1299 | (prepare, check and other idle watchers do not count). That is, as long |
1396 | priority are pending (prepare, check and other idle watchers do not |
1300 | as your process is busy handling sockets or timeouts (or even signals, |
1397 | count).</p> |
1301 | imagine) it will not be triggered. But when your process is idle all idle |
1398 | <p>That is, as long as your process is busy handling sockets or timeouts |
1302 | watchers are being called again and again, once per event loop iteration - |
1399 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1400 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1401 | are pending), the idle watchers are being called once per event loop |
1303 | until stopped, that is, or your process receives more events and becomes |
1402 | iteration - until stopped, that is, or your process receives more events |
1304 | busy.</p> |
1403 | and becomes busy again with higher priority stuff.</p> |
1305 | <p>The most noteworthy effect is that as long as any idle watchers are |
1404 | <p>The most noteworthy effect is that as long as any idle watchers are |
1306 | active, the process will not block when waiting for new events.</p> |
1405 | active, the process will not block when waiting for new events.</p> |
1307 | <p>Apart from keeping your process non-blocking (which is a useful |
1406 | <p>Apart from keeping your process non-blocking (which is a useful |
1308 | effect on its own sometimes), idle watchers are a good place to do |
1407 | effect on its own sometimes), idle watchers are a good place to do |
1309 | "pseudo-background processing", or delay processing stuff to after the |
1408 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
1314 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1413 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1315 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1414 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1316 | believe me.</p> |
1415 | believe me.</p> |
1317 | </dd> |
1416 | </dd> |
1318 | </dl> |
1417 | </dl> |
1319 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
1418 | <p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the |
1320 | callback, free it. Alos, use no error checking, as usual.</p> |
1419 | callback, free it. Also, use no error checking, as usual.</p> |
1321 | <pre> static void |
1420 | <pre> static void |
1322 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1421 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1323 | { |
1422 | { |
1324 | free (w); |
1423 | free (w); |
1325 | // now do something you wanted to do when the program has |
1424 | // now do something you wanted to do when the program has |
… | |
… | |
1399 | |
1498 | |
1400 | // create io watchers for each fd and a timer before blocking |
1499 | // create io watchers for each fd and a timer before blocking |
1401 | static void |
1500 | static void |
1402 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1501 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1403 | { |
1502 | { |
1404 | int timeout = 3600000;truct pollfd fds [nfd]; |
1503 | int timeout = 3600000; |
|
|
1504 | struct pollfd fds [nfd]; |
1405 | // actual code will need to loop here and realloc etc. |
1505 | // actual code will need to loop here and realloc etc. |
1406 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1506 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1407 | |
1507 | |
1408 | /* the callback is illegal, but won't be called as we stop during check */ |
1508 | /* the callback is illegal, but won't be called as we stop during check */ |
1409 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1509 | ev_timer_init (&tw, 0, timeout * 1e-3); |
… | |
… | |
1550 | |
1650 | |
1551 | |
1651 | |
1552 | |
1652 | |
1553 | |
1653 | |
1554 | </div> |
1654 | </div> |
1555 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1655 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1> |
1556 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1656 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1557 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1657 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1558 | <dl> |
1658 | <dl> |
1559 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1659 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1560 | <dd> |
1660 | <dd> |
… | |
… | |
1607 | |
1707 | |
1608 | |
1708 | |
1609 | |
1709 | |
1610 | |
1710 | |
1611 | </div> |
1711 | </div> |
1612 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1712 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1> |
1613 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1713 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1614 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1714 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1615 | emulate the internals of libevent, so here are some usage hints:</p> |
1715 | emulate the internals of libevent, so here are some usage hints:</p> |
1616 | <dl> |
1716 | <dl> |
1617 | <dt>* Use it by including <event.h>, as usual.</dt> |
1717 | <dt>* Use it by including <event.h>, as usual.</dt> |
… | |
… | |
1627 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1727 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1628 | to use the libev header file and library.</dt> |
1728 | to use the libev header file and library.</dt> |
1629 | </dl> |
1729 | </dl> |
1630 | |
1730 | |
1631 | </div> |
1731 | </div> |
1632 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1732 | <h1 id="C_SUPPORT">C++ SUPPORT</h1> |
1633 | <div id="C_SUPPORT_CONTENT"> |
1733 | <div id="C_SUPPORT_CONTENT"> |
1634 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1734 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1635 | you to use some convinience methods to start/stop watchers and also change |
1735 | you to use some convinience methods to start/stop watchers and also change |
1636 | the callback model to a model using method callbacks on objects.</p> |
1736 | the callback model to a model using method callbacks on objects.</p> |
1637 | <p>To use it,</p> |
1737 | <p>To use it,</p> |
… | |
… | |
1732 | |
1832 | |
1733 | |
1833 | |
1734 | </pre> |
1834 | </pre> |
1735 | |
1835 | |
1736 | </div> |
1836 | </div> |
1737 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1837 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
1738 | <div id="MACRO_MAGIC_CONTENT"> |
1838 | <div id="MACRO_MAGIC_CONTENT"> |
1739 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1839 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1740 | <code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and |
1840 | <code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and |
1741 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1841 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1742 | <p>To make it easier to write programs that cope with either variant, the |
1842 | <p>To make it easier to write programs that cope with either variant, the |
1743 | following macros are defined:</p> |
1843 | following macros are defined:</p> |
1744 | <dl> |
1844 | <dl> |
1745 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
1845 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
… | |
… | |
1774 | <dd> |
1874 | <dd> |
1775 | <p>Similar to the other two macros, this gives you the value of the default |
1875 | <p>Similar to the other two macros, this gives you the value of the default |
1776 | loop, if multiple loops are supported ("ev loop default").</p> |
1876 | loop, if multiple loops are supported ("ev loop default").</p> |
1777 | </dd> |
1877 | </dd> |
1778 | </dl> |
1878 | </dl> |
1779 | <p>Example: Declare and initialise a check watcher, working regardless of |
1879 | <p>Example: Declare and initialise a check watcher, utilising the above |
1780 | wether multiple loops are supported or not.</p> |
1880 | macros so it will work regardless of whether multiple loops are supported |
|
|
1881 | or not.</p> |
1781 | <pre> static void |
1882 | <pre> static void |
1782 | check_cb (EV_P_ ev_timer *w, int revents) |
1883 | check_cb (EV_P_ ev_timer *w, int revents) |
1783 | { |
1884 | { |
1784 | ev_check_stop (EV_A_ w); |
1885 | ev_check_stop (EV_A_ w); |
1785 | } |
1886 | } |
… | |
… | |
1787 | ev_check check; |
1888 | ev_check check; |
1788 | ev_check_init (&check, check_cb); |
1889 | ev_check_init (&check, check_cb); |
1789 | ev_check_start (EV_DEFAULT_ &check); |
1890 | ev_check_start (EV_DEFAULT_ &check); |
1790 | ev_loop (EV_DEFAULT_ 0); |
1891 | ev_loop (EV_DEFAULT_ 0); |
1791 | |
1892 | |
1792 | |
|
|
1793 | |
|
|
1794 | |
|
|
1795 | </pre> |
1893 | </pre> |
1796 | |
1894 | |
1797 | </div> |
1895 | </div> |
1798 | <h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1896 | <h1 id="EMBEDDING">EMBEDDING</h1> |
1799 | <div id="EMBEDDING_CONTENT"> |
1897 | <div id="EMBEDDING_CONTENT"> |
1800 | <p>Libev can (and often is) directly embedded into host |
1898 | <p>Libev can (and often is) directly embedded into host |
1801 | applications. Examples of applications that embed it include the Deliantra |
1899 | applications. Examples of applications that embed it include the Deliantra |
1802 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1900 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1803 | and rxvt-unicode.</p> |
1901 | and rxvt-unicode.</p> |
… | |
… | |
1840 | ev_vars.h |
1938 | ev_vars.h |
1841 | ev_wrap.h |
1939 | ev_wrap.h |
1842 | |
1940 | |
1843 | ev_win32.c required on win32 platforms only |
1941 | ev_win32.c required on win32 platforms only |
1844 | |
1942 | |
1845 | ev_select.c only when select backend is enabled (which is by default) |
1943 | ev_select.c only when select backend is enabled (which is enabled by default) |
1846 | ev_poll.c only when poll backend is enabled (disabled by default) |
1944 | ev_poll.c only when poll backend is enabled (disabled by default) |
1847 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1945 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1848 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1946 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1849 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1947 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1850 | |
1948 | |
… | |
… | |
1977 | </dd> |
2075 | </dd> |
1978 | <dt>EV_USE_DEVPOLL</dt> |
2076 | <dt>EV_USE_DEVPOLL</dt> |
1979 | <dd> |
2077 | <dd> |
1980 | <p>reserved for future expansion, works like the USE symbols above.</p> |
2078 | <p>reserved for future expansion, works like the USE symbols above.</p> |
1981 | </dd> |
2079 | </dd> |
|
|
2080 | <dt>EV_USE_INOTIFY</dt> |
|
|
2081 | <dd> |
|
|
2082 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify |
|
|
2083 | interface to speed up <code>ev_stat</code> watchers. Its actual availability will |
|
|
2084 | be detected at runtime.</p> |
|
|
2085 | </dd> |
1982 | <dt>EV_H</dt> |
2086 | <dt>EV_H</dt> |
1983 | <dd> |
2087 | <dd> |
1984 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
2088 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
1985 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
2089 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
1986 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
2090 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
… | |
… | |
2009 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2113 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2010 | additional independent event loops. Otherwise there will be no support |
2114 | additional independent event loops. Otherwise there will be no support |
2011 | for multiple event loops and there is no first event loop pointer |
2115 | for multiple event loops and there is no first event loop pointer |
2012 | argument. Instead, all functions act on the single default loop.</p> |
2116 | argument. Instead, all functions act on the single default loop.</p> |
2013 | </dd> |
2117 | </dd> |
|
|
2118 | <dt>EV_MINPRI</dt> |
|
|
2119 | <dt>EV_MAXPRI</dt> |
|
|
2120 | <dd> |
|
|
2121 | <p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to |
|
|
2122 | <code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can |
|
|
2123 | provide for more priorities by overriding those symbols (usually defined |
|
|
2124 | to be <code>-2</code> and <code>2</code>, respectively).</p> |
|
|
2125 | <p>When doing priority-based operations, libev usually has to linearly search |
|
|
2126 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2127 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2128 | fine.</p> |
|
|
2129 | <p>If your embedding app does not need any priorities, defining these both to |
|
|
2130 | <code>0</code> will save some memory and cpu.</p> |
|
|
2131 | </dd> |
2014 | <dt>EV_PERIODIC_ENABLE</dt> |
2132 | <dt>EV_PERIODIC_ENABLE</dt> |
2015 | <dd> |
2133 | <dd> |
2016 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2134 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2017 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2135 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2018 | code.</p> |
2136 | code.</p> |
2019 | </dd> |
2137 | </dd> |
|
|
2138 | <dt>EV_IDLE_ENABLE</dt> |
|
|
2139 | <dd> |
|
|
2140 | <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If |
|
|
2141 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2142 | code.</p> |
|
|
2143 | </dd> |
2020 | <dt>EV_EMBED_ENABLE</dt> |
2144 | <dt>EV_EMBED_ENABLE</dt> |
2021 | <dd> |
2145 | <dd> |
2022 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
2146 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
2023 | defined to be <code>0</code>, then they are not.</p> |
2147 | defined to be <code>0</code>, then they are not.</p> |
2024 | </dd> |
2148 | </dd> |
… | |
… | |
2041 | <dt>EV_PID_HASHSIZE</dt> |
2165 | <dt>EV_PID_HASHSIZE</dt> |
2042 | <dd> |
2166 | <dd> |
2043 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
2167 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
2044 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
2168 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
2045 | than enough. If you need to manage thousands of children you might want to |
2169 | than enough. If you need to manage thousands of children you might want to |
2046 | increase this value.</p> |
2170 | increase this value (<i>must</i> be a power of two).</p> |
|
|
2171 | </dd> |
|
|
2172 | <dt>EV_INOTIFY_HASHSIZE</dt> |
|
|
2173 | <dd> |
|
|
2174 | <p><code>ev_staz</code> watchers use a small hash table to distribute workload by |
|
|
2175 | inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), |
|
|
2176 | usually more than enough. If you need to manage thousands of <code>ev_stat</code> |
|
|
2177 | watchers you might want to increase this value (<i>must</i> be a power of |
|
|
2178 | two).</p> |
2047 | </dd> |
2179 | </dd> |
2048 | <dt>EV_COMMON</dt> |
2180 | <dt>EV_COMMON</dt> |
2049 | <dd> |
2181 | <dd> |
2050 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2182 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2051 | this macro to a something else you can include more and other types of |
2183 | this macro to a something else you can include more and other types of |
… | |
… | |
2078 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2210 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2079 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2211 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2080 | will be compiled. It is pretty complex because it provides its own header |
2212 | will be compiled. It is pretty complex because it provides its own header |
2081 | file.</p> |
2213 | file.</p> |
2082 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2214 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2083 | that everybody includes and which overrides some autoconf choices:</p> |
2215 | that everybody includes and which overrides some configure choices:</p> |
|
|
2216 | <pre> #define EV_MINIMAL 1 |
2084 | <pre> #define EV_USE_POLL 0 |
2217 | #define EV_USE_POLL 0 |
2085 | #define EV_MULTIPLICITY 0 |
2218 | #define EV_MULTIPLICITY 0 |
2086 | #define EV_PERIODICS 0 |
2219 | #define EV_PERIODIC_ENABLE 0 |
|
|
2220 | #define EV_STAT_ENABLE 0 |
|
|
2221 | #define EV_FORK_ENABLE 0 |
2087 | #define EV_CONFIG_H <config.h> |
2222 | #define EV_CONFIG_H <config.h> |
|
|
2223 | #define EV_MINPRI 0 |
|
|
2224 | #define EV_MAXPRI 0 |
2088 | |
2225 | |
2089 | #include "ev++.h" |
2226 | #include "ev++.h" |
2090 | |
2227 | |
2091 | </pre> |
2228 | </pre> |
2092 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
2229 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
… | |
… | |
2097 | |
2234 | |
2098 | |
2235 | |
2099 | </pre> |
2236 | </pre> |
2100 | |
2237 | |
2101 | </div> |
2238 | </div> |
2102 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2239 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2103 | <div id="COMPLEXITIES_CONTENT"> |
2240 | <div id="COMPLEXITIES_CONTENT"> |
2104 | <p>In this section the complexities of (many of) the algorithms used inside |
2241 | <p>In this section the complexities of (many of) the algorithms used inside |
2105 | libev will be explained. For complexity discussions about backends see the |
2242 | libev will be explained. For complexity discussions about backends see the |
2106 | documentation for <code>ev_default_init</code>.</p> |
2243 | documentation for <code>ev_default_init</code>.</p> |
|
|
2244 | <p>All of the following are about amortised time: If an array needs to be |
|
|
2245 | extended, libev needs to realloc and move the whole array, but this |
|
|
2246 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2247 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2248 | it is much faster and asymptotically approaches constant time.</p> |
2107 | <p> |
2249 | <p> |
2108 | <dl> |
2250 | <dl> |
2109 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2251 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
2252 | <dd> |
|
|
2253 | <p>This means that, when you have a watcher that triggers in one hour and |
|
|
2254 | there are 100 watchers that would trigger before that then inserting will |
|
|
2255 | have to skip those 100 watchers.</p> |
|
|
2256 | </dd> |
2110 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2257 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
2258 | <dd> |
|
|
2259 | <p>That means that for changing a timer costs less than removing/adding them |
|
|
2260 | as only the relative motion in the event queue has to be paid for.</p> |
|
|
2261 | </dd> |
2111 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2262 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
2263 | <dd> |
|
|
2264 | <p>These just add the watcher into an array or at the head of a list. |
2112 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2265 | =item Stopping check/prepare/idle watchers: O(1)</p> |
|
|
2266 | </dd> |
2113 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> |
2267 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
|
|
2268 | <dd> |
|
|
2269 | <p>These watchers are stored in lists then need to be walked to find the |
|
|
2270 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2271 | have many watchers waiting for the same fd or signal).</p> |
|
|
2272 | </dd> |
2114 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2273 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2115 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
2274 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
2275 | <dd> |
|
|
2276 | <p>A change means an I/O watcher gets started or stopped, which requires |
|
|
2277 | libev to recalculate its status (and possibly tell the kernel).</p> |
|
|
2278 | </dd> |
2116 | <dt>Activating one watcher: O(1)</dt> |
2279 | <dt>Activating one watcher: O(1)</dt> |
|
|
2280 | <dt>Priority handling: O(number_of_priorities)</dt> |
|
|
2281 | <dd> |
|
|
2282 | <p>Priorities are implemented by allocating some space for each |
|
|
2283 | priority. When doing priority-based operations, libev usually has to |
|
|
2284 | linearly search all the priorities.</p> |
|
|
2285 | </dd> |
2117 | </dl> |
2286 | </dl> |
2118 | </p> |
2287 | </p> |
2119 | |
2288 | |
2120 | |
2289 | |
2121 | |
2290 | |
2122 | |
2291 | |
2123 | |
2292 | |
2124 | </div> |
2293 | </div> |
2125 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2294 | <h1 id="AUTHOR">AUTHOR</h1> |
2126 | <div id="AUTHOR_CONTENT"> |
2295 | <div id="AUTHOR_CONTENT"> |
2127 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2296 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2128 | |
2297 | |
2129 | </div> |
2298 | </div> |
2130 | </div></body> |
2299 | </div></body> |