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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" /> |
7 | <meta name="inputfile" content="<standard input>" /> |
7 | <meta name="inputfile" content="<standard input>" /> |
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8 | <meta name="outputfile" content="<standard output>" /> |
9 | <meta name="created" content="Tue Nov 27 21:26:46 2007" /> |
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12 | <body> |
12 | <body> |
13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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60 | <li><a href="#AUTHOR">AUTHOR</a> |
60 | <li><a href="#AUTHOR">AUTHOR</a> |
61 | </li> |
61 | </li> |
62 | </ul><hr /> |
62 | </ul><hr /> |
63 | <!-- INDEX END --> |
63 | <!-- INDEX END --> |
64 | |
64 | |
65 | <h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> |
65 | <h1 id="NAME">NAME</h1> |
66 | <div id="NAME_CONTENT"> |
66 | <div id="NAME_CONTENT"> |
67 | <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> |
68 | |
68 | |
69 | </div> |
69 | </div> |
70 | <h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
70 | <h1 id="SYNOPSIS">SYNOPSIS</h1> |
71 | <div id="SYNOPSIS_CONTENT"> |
71 | <div id="SYNOPSIS_CONTENT"> |
72 | <pre> #include <ev.h> |
72 | <pre> #include <ev.h> |
73 | |
73 | |
74 | </pre> |
74 | </pre> |
75 | |
75 | |
76 | </div> |
76 | </div> |
77 | <h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1><p><a href="#TOP" class="toplink">Top</a></p> |
77 | <h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1> |
78 | <div id="EXAMPLE_PROGRAM_CONTENT"> |
78 | <div id="EXAMPLE_PROGRAM_CONTENT"> |
79 | <pre> #include <ev.h> |
79 | <pre> #include <ev.h> |
80 | |
80 | |
81 | ev_io stdin_watcher; |
81 | ev_io stdin_watcher; |
82 | ev_timer timeout_watcher; |
82 | ev_timer timeout_watcher; |
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117 | } |
117 | } |
118 | |
118 | |
119 | </pre> |
119 | </pre> |
120 | |
120 | |
121 | </div> |
121 | </div> |
122 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
122 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
123 | <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> |
124 | <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 |
125 | 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 |
126 | these event sources and provide your program with events.</p> |
129 | these event sources and provide your program with events.</p> |
127 | <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 |
128 | (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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131 | 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 |
132 | 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 |
133 | watcher.</p> |
136 | watcher.</p> |
134 | |
137 | |
135 | </div> |
138 | </div> |
136 | <h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
139 | <h1 id="FEATURES">FEATURES</h1> |
137 | <div id="FEATURES_CONTENT"> |
140 | <div id="FEATURES_CONTENT"> |
138 | <p>Libev supports <code>select</code>, <code>poll</code>, the linux-specific <code>epoll</code>, the |
141 | <p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the |
139 | bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms |
142 | BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms |
140 | for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>), |
143 | for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface |
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144 | (for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers |
141 | absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous |
145 | with customised rescheduling (<code>ev_periodic</code>), synchronous signals |
142 | signals (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and |
146 | (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event |
143 | event watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
147 | watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
144 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
148 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
145 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
149 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
146 | (<code>ev_fork</code>).</p> |
150 | (<code>ev_fork</code>).</p> |
147 | <p>It also is quite fast (see this |
151 | <p>It also is quite fast (see this |
148 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
152 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
149 | for example).</p> |
153 | for example).</p> |
150 | |
154 | |
151 | </div> |
155 | </div> |
152 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
156 | <h1 id="CONVENTIONS">CONVENTIONS</h1> |
153 | <div id="CONVENTIONS_CONTENT"> |
157 | <div id="CONVENTIONS_CONTENT"> |
154 | <p>Libev is very configurable. In this manual the default configuration will |
158 | <p>Libev is very configurable. In this manual the default configuration will |
155 | be described, which supports multiple event loops. For more info about |
159 | be described, which supports multiple event loops. For more info about |
156 | various configuration options please have a look at <strong>EMBED</strong> section in |
160 | various configuration options please have a look at <strong>EMBED</strong> section in |
157 | this manual. If libev was configured without support for multiple event |
161 | this manual. If libev was configured without support for multiple event |
158 | loops, then all functions taking an initial argument of name <code>loop</code> |
162 | loops, then all functions taking an initial argument of name <code>loop</code> |
159 | (which is always of type <code>struct ev_loop *</code>) will not have this argument.</p> |
163 | (which is always of type <code>struct ev_loop *</code>) will not have this argument.</p> |
160 | |
164 | |
161 | </div> |
165 | </div> |
162 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
166 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1> |
163 | <div id="TIME_REPRESENTATION_CONTENT"> |
167 | <div id="TIME_REPRESENTATION_CONTENT"> |
164 | <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 |
165 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
169 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
166 | 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 |
167 | 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 |
168 | 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 |
169 | it, you should treat it as such.</p> |
173 | it, you should treat it as such.</p> |
170 | |
174 | |
171 | </div> |
175 | </div> |
172 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
176 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1> |
173 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
177 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
174 | <p>These functions can be called anytime, even before initialising the |
178 | <p>These functions can be called anytime, even before initialising the |
175 | library in any way.</p> |
179 | library in any way.</p> |
176 | <dl> |
180 | <dl> |
177 | <dt>ev_tstamp ev_time ()</dt> |
181 | <dt>ev_tstamp ev_time ()</dt> |
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229 | 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 |
230 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
234 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
231 | recommended ones.</p> |
235 | recommended ones.</p> |
232 | <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> |
233 | </dd> |
237 | </dd> |
234 | <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt> |
238 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
235 | <dd> |
239 | <dd> |
236 | <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 |
237 | 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 |
238 | 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 |
239 | allocated, the library might abort or take some potentially destructive |
243 | memory needs to be allocated, the library might abort or take some |
240 | 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> |
241 | <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, |
242 | 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, |
243 | 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> |
244 | <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 |
245 | retries).</p> |
250 | retries).</p> |
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285 | </pre> |
290 | </pre> |
286 | </dd> |
291 | </dd> |
287 | </dl> |
292 | </dl> |
288 | |
293 | |
289 | </div> |
294 | </div> |
290 | <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> |
291 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
296 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
292 | <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 |
293 | 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 |
294 | events, and dynamically created loops which do not.</p> |
299 | events, and dynamically created loops which do not.</p> |
295 | <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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324 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
329 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
325 | 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 |
326 | 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 |
327 | around bugs.</p> |
332 | around bugs.</p> |
328 | </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> |
329 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
351 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
330 | <dd> |
352 | <dd> |
331 | <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 |
332 | 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, |
333 | 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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461 | <dt>ev_loop_fork (loop)</dt> |
483 | <dt>ev_loop_fork (loop)</dt> |
462 | <dd> |
484 | <dd> |
463 | <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 |
464 | <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 |
465 | 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> |
466 | </dd> |
497 | </dd> |
467 | <dt>unsigned int ev_backend (loop)</dt> |
498 | <dt>unsigned int ev_backend (loop)</dt> |
468 | <dd> |
499 | <dd> |
469 | <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 |
470 | use.</p> |
501 | use.</p> |
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568 | |
599 | |
569 | |
600 | |
570 | |
601 | |
571 | |
602 | |
572 | </div> |
603 | </div> |
573 | <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> |
574 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
605 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
575 | <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 |
576 | 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 |
577 | 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> |
578 | <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) |
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738 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
769 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
739 | <dd> |
770 | <dd> |
740 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
771 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
741 | 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 |
742 | 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 |
743 | <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), you must not change its priority, and you must |
744 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
775 | make sure the watcher is available to libev (e.g. you cannot <code>free ()</code> |
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776 | it).</p> |
745 | </dd> |
777 | </dd> |
746 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
778 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
747 | <dd> |
779 | <dd> |
748 | <p>Returns the callback currently set on the watcher.</p> |
780 | <p>Returns the callback currently set on the watcher.</p> |
749 | </dd> |
781 | </dd> |
750 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
782 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
751 | <dd> |
783 | <dd> |
752 | <p>Change the callback. You can change the callback at virtually any time |
784 | <p>Change the callback. You can change the callback at virtually any time |
753 | (modulo threads).</p> |
785 | (modulo threads).</p> |
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786 | </dd> |
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787 | <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt> |
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788 | <dt>int ev_priority (ev_TYPE *watcher)</dt> |
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789 | <dd> |
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790 | <p>Set and query the priority of the watcher. The priority is a small |
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791 | integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code> |
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792 | (default: <code>-2</code>). Pending watchers with higher priority will be invoked |
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793 | before watchers with lower priority, but priority will not keep watchers |
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794 | from being executed (except for <code>ev_idle</code> watchers).</p> |
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795 | <p>This means that priorities are <i>only</i> used for ordering callback |
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796 | invocation after new events have been received. This is useful, for |
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797 | example, to reduce latency after idling, or more often, to bind two |
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798 | watchers on the same event and make sure one is called first.</p> |
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799 | <p>If you need to suppress invocation when higher priority events are pending |
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800 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
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801 | <p>You <i>must not</i> change the priority of a watcher as long as it is active or |
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802 | pending.</p> |
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803 | <p>The default priority used by watchers when no priority has been set is |
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804 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
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805 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
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806 | fine, as long as you do not mind that the priority value you query might |
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807 | or might not have been adjusted to be within valid range.</p> |
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808 | </dd> |
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809 | <dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt> |
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810 | <dd> |
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811 | <p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither |
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812 | <code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback |
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813 | can deal with that fact.</p> |
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814 | </dd> |
|
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815 | <dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt> |
|
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816 | <dd> |
|
|
817 | <p>If the watcher is pending, this function returns clears its pending status |
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818 | and returns its <code>revents</code> bitset (as if its callback was invoked). If the |
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819 | watcher isn't pending it does nothing and returns <code>0</code>.</p> |
754 | </dd> |
820 | </dd> |
755 | </dl> |
821 | </dl> |
756 | |
822 | |
757 | |
823 | |
758 | |
824 | |
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783 | struct my_io *w = (struct my_io *)w_; |
849 | struct my_io *w = (struct my_io *)w_; |
784 | ... |
850 | ... |
785 | } |
851 | } |
786 | |
852 | |
787 | </pre> |
853 | </pre> |
788 | <p>More interesting and less C-conformant ways of catsing your callback type |
854 | <p>More interesting and less C-conformant ways of casting your callback type |
789 | have been omitted....</p> |
855 | instead have been omitted.</p> |
|
|
856 | <p>Another common scenario is having some data structure with multiple |
|
|
857 | watchers:</p> |
|
|
858 | <pre> struct my_biggy |
|
|
859 | { |
|
|
860 | int some_data; |
|
|
861 | ev_timer t1; |
|
|
862 | ev_timer t2; |
|
|
863 | } |
790 | |
864 | |
|
|
865 | </pre> |
|
|
866 | <p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated, |
|
|
867 | you need to use <code>offsetof</code>:</p> |
|
|
868 | <pre> #include <stddef.h> |
791 | |
869 | |
|
|
870 | static void |
|
|
871 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
872 | { |
|
|
873 | struct my_biggy big = (struct my_biggy * |
|
|
874 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
875 | } |
792 | |
876 | |
|
|
877 | static void |
|
|
878 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
879 | { |
|
|
880 | struct my_biggy big = (struct my_biggy * |
|
|
881 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
882 | } |
793 | |
883 | |
794 | |
884 | |
|
|
885 | |
|
|
886 | |
|
|
887 | </pre> |
|
|
888 | |
795 | </div> |
889 | </div> |
796 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
890 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
797 | <div id="WATCHER_TYPES_CONTENT"> |
891 | <div id="WATCHER_TYPES_CONTENT"> |
798 | <p>This section describes each watcher in detail, but will not repeat |
892 | <p>This section describes each watcher in detail, but will not repeat |
799 | information given in the last section. Any initialisation/set macros, |
893 | information given in the last section. Any initialisation/set macros, |
800 | functions and members specific to the watcher type are explained.</p> |
894 | functions and members specific to the watcher type are explained.</p> |
801 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
895 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
… | |
… | |
841 | this situation even with a relatively standard program structure. Thus |
935 | this situation even with a relatively standard program structure. Thus |
842 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
936 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
843 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
937 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
844 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
938 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
845 | play around with an Xlib connection), then you have to seperately re-test |
939 | play around with an Xlib connection), then you have to seperately re-test |
846 | wether a file descriptor is really ready with a known-to-be good interface |
940 | whether a file descriptor is really ready with a known-to-be good interface |
847 | such as poll (fortunately in our Xlib example, Xlib already does this on |
941 | such as poll (fortunately in our Xlib example, Xlib already does this on |
848 | its own, so its quite safe to use).</p> |
942 | its own, so its quite safe to use).</p> |
849 | <dl> |
943 | <dl> |
850 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
944 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
851 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
945 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
… | |
… | |
922 | </dd> |
1016 | </dd> |
923 | <dt>ev_timer_again (loop)</dt> |
1017 | <dt>ev_timer_again (loop)</dt> |
924 | <dd> |
1018 | <dd> |
925 | <p>This will act as if the timer timed out and restart it again if it is |
1019 | <p>This will act as if the timer timed out and restart it again if it is |
926 | repeating. The exact semantics are:</p> |
1020 | repeating. The exact semantics are:</p> |
|
|
1021 | <p>If the timer is pending, its pending status is cleared.</p> |
927 | <p>If the timer is started but nonrepeating, stop it.</p> |
1022 | <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p> |
928 | <p>If the timer is repeating, either start it if necessary (with the repeat |
1023 | <p>If the timer is repeating, either start it if necessary (with the |
929 | value), or reset the running timer to the repeat value.</p> |
1024 | <code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p> |
930 | <p>This sounds a bit complicated, but here is a useful and typical |
1025 | <p>This sounds a bit complicated, but here is a useful and typical |
931 | example: Imagine you have a tcp connection and you want a so-called |
1026 | example: Imagine you have a tcp connection and you want a so-called idle |
932 | idle timeout, that is, you want to be called when there have been, |
1027 | timeout, that is, you want to be called when there have been, say, 60 |
933 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1028 | seconds of inactivity on the socket. The easiest way to do this is to |
934 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
1029 | configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call |
935 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
1030 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
936 | you go into an idle state where you do not expect data to travel on the |
1031 | you go into an idle state where you do not expect data to travel on the |
937 | socket, you can stop the timer, and again will automatically restart it if |
1032 | socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will |
938 | need be.</p> |
1033 | automatically restart it if need be.</p> |
939 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
1034 | <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code> |
940 | and only ever use the <code>repeat</code> value:</p> |
1035 | altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p> |
941 | <pre> ev_timer_init (timer, callback, 0., 5.); |
1036 | <pre> ev_timer_init (timer, callback, 0., 5.); |
942 | ev_timer_again (loop, timer); |
1037 | ev_timer_again (loop, timer); |
943 | ... |
1038 | ... |
944 | timer->again = 17.; |
1039 | timer->again = 17.; |
945 | ev_timer_again (loop, timer); |
1040 | ev_timer_again (loop, timer); |
946 | ... |
1041 | ... |
947 | timer->again = 10.; |
1042 | timer->again = 10.; |
948 | ev_timer_again (loop, timer); |
1043 | ev_timer_again (loop, timer); |
949 | |
1044 | |
950 | </pre> |
1045 | </pre> |
951 | <p>This is more efficient then stopping/starting the timer eahc time you want |
1046 | <p>This is more slightly efficient then stopping/starting the timer each time |
952 | to modify its timeout value.</p> |
1047 | you want to modify its timeout value.</p> |
953 | </dd> |
1048 | </dd> |
954 | <dt>ev_tstamp repeat [read-write]</dt> |
1049 | <dt>ev_tstamp repeat [read-write]</dt> |
955 | <dd> |
1050 | <dd> |
956 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
1051 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
957 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
1052 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
… | |
… | |
1218 | <p>The path does not need to exist: changing from "path exists" to "path does |
1313 | <p>The path does not need to exist: changing from "path exists" to "path does |
1219 | not exist" is a status change like any other. The condition "path does |
1314 | not exist" is a status change like any other. The condition "path does |
1220 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1315 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1221 | otherwise always forced to be at least one) and all the other fields of |
1316 | otherwise always forced to be at least one) and all the other fields of |
1222 | the stat buffer having unspecified contents.</p> |
1317 | the stat buffer having unspecified contents.</p> |
|
|
1318 | <p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is |
|
|
1319 | relative and your working directory changes, the behaviour is undefined.</p> |
1223 | <p>Since there is no standard to do this, the portable implementation simply |
1320 | <p>Since there is no standard to do this, the portable implementation simply |
1224 | calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You |
1321 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
1225 | can specify a recommended polling interval for this case. If you specify |
1322 | can specify a recommended polling interval for this case. If you specify |
1226 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1323 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1227 | unspecified default</i> value will be used (which you can expect to be around |
1324 | unspecified default</i> value will be used (which you can expect to be around |
1228 | five seconds, although this might change dynamically). Libev will also |
1325 | five seconds, although this might change dynamically). Libev will also |
1229 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
1326 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
1230 | usually overkill.</p> |
1327 | usually overkill.</p> |
1231 | <p>This watcher type is not meant for massive numbers of stat watchers, |
1328 | <p>This watcher type is not meant for massive numbers of stat watchers, |
1232 | as even with OS-supported change notifications, this can be |
1329 | as even with OS-supported change notifications, this can be |
1233 | resource-intensive.</p> |
1330 | resource-intensive.</p> |
1234 | <p>At the time of this writing, no specific OS backends are implemented, but |
1331 | <p>At the time of this writing, only the Linux inotify interface is |
1235 | if demand increases, at least a kqueue and inotify backend will be added.</p> |
1332 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1333 | reader). Inotify will be used to give hints only and should not change the |
|
|
1334 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
|
|
1335 | to fall back to regular polling again even with inotify, but changes are |
|
|
1336 | usually detected immediately, and if the file exists there will be no |
|
|
1337 | polling.</p> |
1236 | <dl> |
1338 | <dl> |
1237 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1339 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1238 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1340 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1239 | <dd> |
1341 | <dd> |
1240 | <p>Configures the watcher to wait for status changes of the given |
1342 | <p>Configures the watcher to wait for status changes of the given |
… | |
… | |
1303 | </pre> |
1405 | </pre> |
1304 | |
1406 | |
1305 | </div> |
1407 | </div> |
1306 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1408 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1307 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1409 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1308 | <p>Idle watchers trigger events when there are no other events are pending |
1410 | <p>Idle watchers trigger events when no other events of the same or higher |
1309 | (prepare, check and other idle watchers do not count). That is, as long |
1411 | priority are pending (prepare, check and other idle watchers do not |
1310 | as your process is busy handling sockets or timeouts (or even signals, |
1412 | count).</p> |
1311 | imagine) it will not be triggered. But when your process is idle all idle |
1413 | <p>That is, as long as your process is busy handling sockets or timeouts |
1312 | watchers are being called again and again, once per event loop iteration - |
1414 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1415 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1416 | are pending), the idle watchers are being called once per event loop |
1313 | until stopped, that is, or your process receives more events and becomes |
1417 | iteration - until stopped, that is, or your process receives more events |
1314 | busy.</p> |
1418 | and becomes busy again with higher priority stuff.</p> |
1315 | <p>The most noteworthy effect is that as long as any idle watchers are |
1419 | <p>The most noteworthy effect is that as long as any idle watchers are |
1316 | active, the process will not block when waiting for new events.</p> |
1420 | active, the process will not block when waiting for new events.</p> |
1317 | <p>Apart from keeping your process non-blocking (which is a useful |
1421 | <p>Apart from keeping your process non-blocking (which is a useful |
1318 | effect on its own sometimes), idle watchers are a good place to do |
1422 | effect on its own sometimes), idle watchers are a good place to do |
1319 | "pseudo-background processing", or delay processing stuff to after the |
1423 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
1409 | |
1513 | |
1410 | // create io watchers for each fd and a timer before blocking |
1514 | // create io watchers for each fd and a timer before blocking |
1411 | static void |
1515 | static void |
1412 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1516 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1413 | { |
1517 | { |
1414 | int timeout = 3600000;truct pollfd fds [nfd]; |
1518 | int timeout = 3600000; |
|
|
1519 | struct pollfd fds [nfd]; |
1415 | // actual code will need to loop here and realloc etc. |
1520 | // actual code will need to loop here and realloc etc. |
1416 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1521 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1417 | |
1522 | |
1418 | /* the callback is illegal, but won't be called as we stop during check */ |
1523 | /* the callback is illegal, but won't be called as we stop during check */ |
1419 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1524 | ev_timer_init (&tw, 0, timeout * 1e-3); |
… | |
… | |
1560 | |
1665 | |
1561 | |
1666 | |
1562 | |
1667 | |
1563 | |
1668 | |
1564 | </div> |
1669 | </div> |
1565 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1670 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1> |
1566 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1671 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1567 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1672 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1568 | <dl> |
1673 | <dl> |
1569 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1674 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1570 | <dd> |
1675 | <dd> |
… | |
… | |
1617 | |
1722 | |
1618 | |
1723 | |
1619 | |
1724 | |
1620 | |
1725 | |
1621 | </div> |
1726 | </div> |
1622 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1727 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1> |
1623 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1728 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1624 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1729 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1625 | emulate the internals of libevent, so here are some usage hints:</p> |
1730 | emulate the internals of libevent, so here are some usage hints:</p> |
1626 | <dl> |
1731 | <dl> |
1627 | <dt>* Use it by including <event.h>, as usual.</dt> |
1732 | <dt>* Use it by including <event.h>, as usual.</dt> |
… | |
… | |
1637 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1742 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1638 | to use the libev header file and library.</dt> |
1743 | to use the libev header file and library.</dt> |
1639 | </dl> |
1744 | </dl> |
1640 | |
1745 | |
1641 | </div> |
1746 | </div> |
1642 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1747 | <h1 id="C_SUPPORT">C++ SUPPORT</h1> |
1643 | <div id="C_SUPPORT_CONTENT"> |
1748 | <div id="C_SUPPORT_CONTENT"> |
1644 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1749 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1645 | you to use some convinience methods to start/stop watchers and also change |
1750 | you to use some convinience methods to start/stop watchers and also change |
1646 | the callback model to a model using method callbacks on objects.</p> |
1751 | the callback model to a model using method callbacks on objects.</p> |
1647 | <p>To use it,</p> |
1752 | <p>To use it,</p> |
1648 | <pre> #include <ev++.h> |
1753 | <pre> #include <ev++.h> |
1649 | |
1754 | |
1650 | </pre> |
1755 | </pre> |
1651 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
1756 | <p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many |
1652 | and puts all of its definitions (many of them macros) into the global |
1757 | of them macros) into the global namespace. All C++ specific things are |
1653 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
1758 | put into the <code>ev</code> namespace. It should support all the same embedding |
1654 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
1759 | options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p> |
1655 | <code>EV_MULTIPLICITY</code>.</p> |
1760 | <p>Care has been taken to keep the overhead low. The only data member the C++ |
|
|
1761 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1762 | that the watcher is associated with (or no additional members at all if |
|
|
1763 | you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p> |
|
|
1764 | <p>Currently, functions, and static and non-static member functions can be |
|
|
1765 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1766 | need one additional pointer for context. If you need support for other |
|
|
1767 | types of functors please contact the author (preferably after implementing |
|
|
1768 | it).</p> |
1656 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1769 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1657 | <dl> |
1770 | <dl> |
1658 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1771 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1659 | <dd> |
1772 | <dd> |
1660 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
1773 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
… | |
… | |
1671 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1784 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1672 | defines by many implementations.</p> |
1785 | defines by many implementations.</p> |
1673 | <p>All of those classes have these methods:</p> |
1786 | <p>All of those classes have these methods:</p> |
1674 | <p> |
1787 | <p> |
1675 | <dl> |
1788 | <dl> |
1676 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
1789 | <dt>ev::TYPE::TYPE ()</dt> |
1677 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
1790 | <dt>ev::TYPE::TYPE (struct ev_loop *)</dt> |
1678 | <dt>ev::TYPE::~TYPE</dt> |
1791 | <dt>ev::TYPE::~TYPE</dt> |
1679 | <dd> |
1792 | <dd> |
1680 | <p>The constructor takes a pointer to an object and a method pointer to |
1793 | <p>The constructor (optionally) takes an event loop to associate the watcher |
1681 | the event handler callback to call in this class. The constructor calls |
1794 | with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p> |
1682 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
1795 | <p>The constructor calls <code>ev_init</code> for you, which means you have to call the |
1683 | before starting it. If you do not specify a loop then the constructor |
1796 | <code>set</code> method before starting it.</p> |
1684 | automatically associates the default loop with this watcher.</p> |
1797 | <p>It will not set a callback, however: You have to call the templated <code>set</code> |
|
|
1798 | method to set a callback before you can start the watcher.</p> |
|
|
1799 | <p>(The reason why you have to use a method is a limitation in C++ which does |
|
|
1800 | not allow explicit template arguments for constructors).</p> |
1685 | <p>The destructor automatically stops the watcher if it is active.</p> |
1801 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1802 | </dd> |
|
|
1803 | <dt>w->set<class, &class::method> (object *)</dt> |
|
|
1804 | <dd> |
|
|
1805 | <p>This method sets the callback method to call. The method has to have a |
|
|
1806 | signature of <code>void (*)(ev_TYPE &, int)</code>, it receives the watcher as |
|
|
1807 | first argument and the <code>revents</code> as second. The object must be given as |
|
|
1808 | parameter and is stored in the <code>data</code> member of the watcher.</p> |
|
|
1809 | <p>This method synthesizes efficient thunking code to call your method from |
|
|
1810 | the C callback that libev requires. If your compiler can inline your |
|
|
1811 | callback (i.e. it is visible to it at the place of the <code>set</code> call and |
|
|
1812 | your compiler is good :), then the method will be fully inlined into the |
|
|
1813 | thunking function, making it as fast as a direct C callback.</p> |
|
|
1814 | <p>Example: simple class declaration and watcher initialisation</p> |
|
|
1815 | <pre> struct myclass |
|
|
1816 | { |
|
|
1817 | void io_cb (ev::io &w, int revents) { } |
|
|
1818 | } |
|
|
1819 | |
|
|
1820 | myclass obj; |
|
|
1821 | ev::io iow; |
|
|
1822 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1823 | |
|
|
1824 | </pre> |
|
|
1825 | </dd> |
|
|
1826 | <dt>w->set<function> (void *data = 0)</dt> |
|
|
1827 | <dd> |
|
|
1828 | <p>Also sets a callback, but uses a static method or plain function as |
|
|
1829 | callback. The optional <code>data</code> argument will be stored in the watcher's |
|
|
1830 | <code>data</code> member and is free for you to use.</p> |
|
|
1831 | <p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &w, int)</code>.</p> |
|
|
1832 | <p>See the method-<code>set</code> above for more details.</p> |
|
|
1833 | <p>Example:</p> |
|
|
1834 | <pre> static void io_cb (ev::io &w, int revents) { } |
|
|
1835 | iow.set <io_cb> (); |
|
|
1836 | |
|
|
1837 | </pre> |
1686 | </dd> |
1838 | </dd> |
1687 | <dt>w->set (struct ev_loop *)</dt> |
1839 | <dt>w->set (struct ev_loop *)</dt> |
1688 | <dd> |
1840 | <dd> |
1689 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
1841 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
1690 | do this when the watcher is inactive (and not pending either).</p> |
1842 | do this when the watcher is inactive (and not pending either).</p> |
1691 | </dd> |
1843 | </dd> |
1692 | <dt>w->set ([args])</dt> |
1844 | <dt>w->set ([args])</dt> |
1693 | <dd> |
1845 | <dd> |
1694 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
1846 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
1695 | called at least once. Unlike the C counterpart, an active watcher gets |
1847 | called at least once. Unlike the C counterpart, an active watcher gets |
1696 | automatically stopped and restarted.</p> |
1848 | automatically stopped and restarted when reconfiguring it with this |
|
|
1849 | method.</p> |
1697 | </dd> |
1850 | </dd> |
1698 | <dt>w->start ()</dt> |
1851 | <dt>w->start ()</dt> |
1699 | <dd> |
1852 | <dd> |
1700 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
1853 | <p>Starts the watcher. Note that there is no <code>loop</code> argument, as the |
1701 | constructor already takes the loop.</p> |
1854 | constructor already stores the event loop.</p> |
1702 | </dd> |
1855 | </dd> |
1703 | <dt>w->stop ()</dt> |
1856 | <dt>w->stop ()</dt> |
1704 | <dd> |
1857 | <dd> |
1705 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1858 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1706 | </dd> |
1859 | </dd> |
… | |
… | |
1730 | |
1883 | |
1731 | myclass (); |
1884 | myclass (); |
1732 | } |
1885 | } |
1733 | |
1886 | |
1734 | myclass::myclass (int fd) |
1887 | myclass::myclass (int fd) |
1735 | : io (this, &myclass::io_cb), |
|
|
1736 | idle (this, &myclass::idle_cb) |
|
|
1737 | { |
1888 | { |
|
|
1889 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1890 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1891 | |
1738 | io.start (fd, ev::READ); |
1892 | io.start (fd, ev::READ); |
1739 | } |
1893 | } |
1740 | |
1894 | |
1741 | |
1895 | |
1742 | |
1896 | |
1743 | |
1897 | |
1744 | </pre> |
1898 | </pre> |
1745 | |
1899 | |
1746 | </div> |
1900 | </div> |
1747 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1901 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
1748 | <div id="MACRO_MAGIC_CONTENT"> |
1902 | <div id="MACRO_MAGIC_CONTENT"> |
1749 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1903 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1750 | <code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and |
1904 | <code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and |
1751 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1905 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1752 | <p>To make it easier to write programs that cope with either variant, the |
1906 | <p>To make it easier to write programs that cope with either variant, the |
1753 | following macros are defined:</p> |
1907 | following macros are defined:</p> |
1754 | <dl> |
1908 | <dl> |
1755 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
1909 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
… | |
… | |
1784 | <dd> |
1938 | <dd> |
1785 | <p>Similar to the other two macros, this gives you the value of the default |
1939 | <p>Similar to the other two macros, this gives you the value of the default |
1786 | loop, if multiple loops are supported ("ev loop default").</p> |
1940 | loop, if multiple loops are supported ("ev loop default").</p> |
1787 | </dd> |
1941 | </dd> |
1788 | </dl> |
1942 | </dl> |
1789 | <p>Example: Declare and initialise a check watcher, working regardless of |
1943 | <p>Example: Declare and initialise a check watcher, utilising the above |
1790 | wether multiple loops are supported or not.</p> |
1944 | macros so it will work regardless of whether multiple loops are supported |
|
|
1945 | or not.</p> |
1791 | <pre> static void |
1946 | <pre> static void |
1792 | check_cb (EV_P_ ev_timer *w, int revents) |
1947 | check_cb (EV_P_ ev_timer *w, int revents) |
1793 | { |
1948 | { |
1794 | ev_check_stop (EV_A_ w); |
1949 | ev_check_stop (EV_A_ w); |
1795 | } |
1950 | } |
… | |
… | |
1797 | ev_check check; |
1952 | ev_check check; |
1798 | ev_check_init (&check, check_cb); |
1953 | ev_check_init (&check, check_cb); |
1799 | ev_check_start (EV_DEFAULT_ &check); |
1954 | ev_check_start (EV_DEFAULT_ &check); |
1800 | ev_loop (EV_DEFAULT_ 0); |
1955 | ev_loop (EV_DEFAULT_ 0); |
1801 | |
1956 | |
1802 | |
|
|
1803 | |
|
|
1804 | |
|
|
1805 | </pre> |
1957 | </pre> |
1806 | |
1958 | |
1807 | </div> |
1959 | </div> |
1808 | <h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1960 | <h1 id="EMBEDDING">EMBEDDING</h1> |
1809 | <div id="EMBEDDING_CONTENT"> |
1961 | <div id="EMBEDDING_CONTENT"> |
1810 | <p>Libev can (and often is) directly embedded into host |
1962 | <p>Libev can (and often is) directly embedded into host |
1811 | applications. Examples of applications that embed it include the Deliantra |
1963 | applications. Examples of applications that embed it include the Deliantra |
1812 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1964 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1813 | and rxvt-unicode.</p> |
1965 | and rxvt-unicode.</p> |
… | |
… | |
1850 | ev_vars.h |
2002 | ev_vars.h |
1851 | ev_wrap.h |
2003 | ev_wrap.h |
1852 | |
2004 | |
1853 | ev_win32.c required on win32 platforms only |
2005 | ev_win32.c required on win32 platforms only |
1854 | |
2006 | |
1855 | ev_select.c only when select backend is enabled (which is by default) |
2007 | ev_select.c only when select backend is enabled (which is enabled by default) |
1856 | ev_poll.c only when poll backend is enabled (disabled by default) |
2008 | ev_poll.c only when poll backend is enabled (disabled by default) |
1857 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2009 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1858 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2010 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1859 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2011 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1860 | |
2012 | |
… | |
… | |
1987 | </dd> |
2139 | </dd> |
1988 | <dt>EV_USE_DEVPOLL</dt> |
2140 | <dt>EV_USE_DEVPOLL</dt> |
1989 | <dd> |
2141 | <dd> |
1990 | <p>reserved for future expansion, works like the USE symbols above.</p> |
2142 | <p>reserved for future expansion, works like the USE symbols above.</p> |
1991 | </dd> |
2143 | </dd> |
|
|
2144 | <dt>EV_USE_INOTIFY</dt> |
|
|
2145 | <dd> |
|
|
2146 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify |
|
|
2147 | interface to speed up <code>ev_stat</code> watchers. Its actual availability will |
|
|
2148 | be detected at runtime.</p> |
|
|
2149 | </dd> |
1992 | <dt>EV_H</dt> |
2150 | <dt>EV_H</dt> |
1993 | <dd> |
2151 | <dd> |
1994 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
2152 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
1995 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
2153 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
1996 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
2154 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
… | |
… | |
2019 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2177 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2020 | additional independent event loops. Otherwise there will be no support |
2178 | additional independent event loops. Otherwise there will be no support |
2021 | for multiple event loops and there is no first event loop pointer |
2179 | for multiple event loops and there is no first event loop pointer |
2022 | argument. Instead, all functions act on the single default loop.</p> |
2180 | argument. Instead, all functions act on the single default loop.</p> |
2023 | </dd> |
2181 | </dd> |
|
|
2182 | <dt>EV_MINPRI</dt> |
|
|
2183 | <dt>EV_MAXPRI</dt> |
|
|
2184 | <dd> |
|
|
2185 | <p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to |
|
|
2186 | <code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can |
|
|
2187 | provide for more priorities by overriding those symbols (usually defined |
|
|
2188 | to be <code>-2</code> and <code>2</code>, respectively).</p> |
|
|
2189 | <p>When doing priority-based operations, libev usually has to linearly search |
|
|
2190 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2191 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2192 | fine.</p> |
|
|
2193 | <p>If your embedding app does not need any priorities, defining these both to |
|
|
2194 | <code>0</code> will save some memory and cpu.</p> |
|
|
2195 | </dd> |
2024 | <dt>EV_PERIODIC_ENABLE</dt> |
2196 | <dt>EV_PERIODIC_ENABLE</dt> |
2025 | <dd> |
2197 | <dd> |
2026 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2198 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2027 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2199 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2028 | code.</p> |
2200 | code.</p> |
2029 | </dd> |
2201 | </dd> |
|
|
2202 | <dt>EV_IDLE_ENABLE</dt> |
|
|
2203 | <dd> |
|
|
2204 | <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If |
|
|
2205 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2206 | code.</p> |
|
|
2207 | </dd> |
2030 | <dt>EV_EMBED_ENABLE</dt> |
2208 | <dt>EV_EMBED_ENABLE</dt> |
2031 | <dd> |
2209 | <dd> |
2032 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
2210 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
2033 | defined to be <code>0</code>, then they are not.</p> |
2211 | defined to be <code>0</code>, then they are not.</p> |
2034 | </dd> |
2212 | </dd> |
… | |
… | |
2051 | <dt>EV_PID_HASHSIZE</dt> |
2229 | <dt>EV_PID_HASHSIZE</dt> |
2052 | <dd> |
2230 | <dd> |
2053 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
2231 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
2054 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
2232 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
2055 | than enough. If you need to manage thousands of children you might want to |
2233 | than enough. If you need to manage thousands of children you might want to |
2056 | increase this value.</p> |
2234 | increase this value (<i>must</i> be a power of two).</p> |
|
|
2235 | </dd> |
|
|
2236 | <dt>EV_INOTIFY_HASHSIZE</dt> |
|
|
2237 | <dd> |
|
|
2238 | <p><code>ev_staz</code> watchers use a small hash table to distribute workload by |
|
|
2239 | inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), |
|
|
2240 | usually more than enough. If you need to manage thousands of <code>ev_stat</code> |
|
|
2241 | watchers you might want to increase this value (<i>must</i> be a power of |
|
|
2242 | two).</p> |
2057 | </dd> |
2243 | </dd> |
2058 | <dt>EV_COMMON</dt> |
2244 | <dt>EV_COMMON</dt> |
2059 | <dd> |
2245 | <dd> |
2060 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2246 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2061 | this macro to a something else you can include more and other types of |
2247 | this macro to a something else you can include more and other types of |
… | |
… | |
2088 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2274 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2089 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2275 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2090 | will be compiled. It is pretty complex because it provides its own header |
2276 | will be compiled. It is pretty complex because it provides its own header |
2091 | file.</p> |
2277 | file.</p> |
2092 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2278 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2093 | that everybody includes and which overrides some autoconf choices:</p> |
2279 | that everybody includes and which overrides some configure choices:</p> |
|
|
2280 | <pre> #define EV_MINIMAL 1 |
2094 | <pre> #define EV_USE_POLL 0 |
2281 | #define EV_USE_POLL 0 |
2095 | #define EV_MULTIPLICITY 0 |
2282 | #define EV_MULTIPLICITY 0 |
2096 | #define EV_PERIODICS 0 |
2283 | #define EV_PERIODIC_ENABLE 0 |
|
|
2284 | #define EV_STAT_ENABLE 0 |
|
|
2285 | #define EV_FORK_ENABLE 0 |
2097 | #define EV_CONFIG_H <config.h> |
2286 | #define EV_CONFIG_H <config.h> |
|
|
2287 | #define EV_MINPRI 0 |
|
|
2288 | #define EV_MAXPRI 0 |
2098 | |
2289 | |
2099 | #include "ev++.h" |
2290 | #include "ev++.h" |
2100 | |
2291 | |
2101 | </pre> |
2292 | </pre> |
2102 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
2293 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
… | |
… | |
2107 | |
2298 | |
2108 | |
2299 | |
2109 | </pre> |
2300 | </pre> |
2110 | |
2301 | |
2111 | </div> |
2302 | </div> |
2112 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2303 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2113 | <div id="COMPLEXITIES_CONTENT"> |
2304 | <div id="COMPLEXITIES_CONTENT"> |
2114 | <p>In this section the complexities of (many of) the algorithms used inside |
2305 | <p>In this section the complexities of (many of) the algorithms used inside |
2115 | libev will be explained. For complexity discussions about backends see the |
2306 | libev will be explained. For complexity discussions about backends see the |
2116 | documentation for <code>ev_default_init</code>.</p> |
2307 | documentation for <code>ev_default_init</code>.</p> |
|
|
2308 | <p>All of the following are about amortised time: If an array needs to be |
|
|
2309 | extended, libev needs to realloc and move the whole array, but this |
|
|
2310 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2311 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2312 | it is much faster and asymptotically approaches constant time.</p> |
2117 | <p> |
2313 | <p> |
2118 | <dl> |
2314 | <dl> |
2119 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2315 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
2316 | <dd> |
|
|
2317 | <p>This means that, when you have a watcher that triggers in one hour and |
|
|
2318 | there are 100 watchers that would trigger before that then inserting will |
|
|
2319 | have to skip those 100 watchers.</p> |
|
|
2320 | </dd> |
2120 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2321 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
2322 | <dd> |
|
|
2323 | <p>That means that for changing a timer costs less than removing/adding them |
|
|
2324 | as only the relative motion in the event queue has to be paid for.</p> |
|
|
2325 | </dd> |
2121 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2326 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
2327 | <dd> |
|
|
2328 | <p>These just add the watcher into an array or at the head of a list. |
2122 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2329 | =item Stopping check/prepare/idle watchers: O(1)</p> |
|
|
2330 | </dd> |
2123 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> |
2331 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
|
|
2332 | <dd> |
|
|
2333 | <p>These watchers are stored in lists then need to be walked to find the |
|
|
2334 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2335 | have many watchers waiting for the same fd or signal).</p> |
|
|
2336 | </dd> |
2124 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2337 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2125 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
2338 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
2339 | <dd> |
|
|
2340 | <p>A change means an I/O watcher gets started or stopped, which requires |
|
|
2341 | libev to recalculate its status (and possibly tell the kernel).</p> |
|
|
2342 | </dd> |
2126 | <dt>Activating one watcher: O(1)</dt> |
2343 | <dt>Activating one watcher: O(1)</dt> |
|
|
2344 | <dt>Priority handling: O(number_of_priorities)</dt> |
|
|
2345 | <dd> |
|
|
2346 | <p>Priorities are implemented by allocating some space for each |
|
|
2347 | priority. When doing priority-based operations, libev usually has to |
|
|
2348 | linearly search all the priorities.</p> |
|
|
2349 | </dd> |
2127 | </dl> |
2350 | </dl> |
2128 | </p> |
2351 | </p> |
2129 | |
2352 | |
2130 | |
2353 | |
2131 | |
2354 | |
2132 | |
2355 | |
2133 | |
2356 | |
2134 | </div> |
2357 | </div> |
2135 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2358 | <h1 id="AUTHOR">AUTHOR</h1> |
2136 | <div id="AUTHOR_CONTENT"> |
2359 | <div id="AUTHOR_CONTENT"> |
2137 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2360 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2138 | |
2361 | |
2139 | </div> |
2362 | </div> |
2140 | </div></body> |
2363 | </div></body> |