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4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
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14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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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> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
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22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
22 | <li><a href="#TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
24 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
25 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | </ul> |
27 | </ul> |
27 | </li> |
28 | </li> |
28 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
29 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
29 | <ul><li><a href="#struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</a></li> |
30 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> |
30 | <li><a href="#struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</a></li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
31 | <li><a href="#ev_periodic_to_cron_or_not_to_cron_i">ev_periodic - to cron or not to cron it</a></li> |
32 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> |
32 | <li><a href="#ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</a></li> |
33 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
33 | <li><a href="#ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</a></li> |
34 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
34 | <li><a href="#ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</a></li> |
35 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
35 | <li><a href="#prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</a></li> |
36 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
36 | </ul> |
37 | </ul> |
37 | </li> |
38 | </li> |
38 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
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40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
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41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
39 | <li><a href="#AUTHOR">AUTHOR</a> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
40 | </li> |
43 | </li> |
41 | </ul><hr /> |
44 | </ul><hr /> |
42 | <!-- INDEX END --> |
45 | <!-- INDEX END --> |
43 | |
46 | |
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72 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
75 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
73 | kqueue mechanisms for file descriptor events, relative timers, absolute |
76 | kqueue mechanisms for file descriptor events, relative timers, absolute |
74 | timers with customised rescheduling, signal events, process status change |
77 | timers with customised rescheduling, signal events, process status change |
75 | events (related to SIGCHLD), and event watchers dealing with the event |
78 | events (related to SIGCHLD), and event watchers dealing with the event |
76 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
79 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
77 | fast (see a <b>http://libev.schmorp.de/bench.html</b> (<cite>benchmark</cite>) comparing it |
80 | fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing |
78 | to libevent).</p> |
81 | it to libevent for example).</p> |
79 | |
82 | |
80 | </div> |
83 | </div> |
81 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
84 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
82 | <div id="CONVENTIONS_CONTENT"> |
85 | <div id="CONVENTIONS_CONTENT"> |
83 | <p>Libev is very configurable. In this manual the default configuration |
86 | <p>Libev is very configurable. In this manual the default configuration |
84 | will be described, which supports multiple event loops. For more info |
87 | will be described, which supports multiple event loops. For more info |
85 | about various configuraiton options please have a look at the file |
88 | about various configuration options please have a look at the file |
86 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
89 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
87 | support for multiple event loops, then all functions taking an initial |
90 | support for multiple event loops, then all functions taking an initial |
88 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
91 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
89 | will not have this argument.</p> |
92 | will not have this argument.</p> |
90 | |
93 | |
91 | </div> |
94 | </div> |
92 | <h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
95 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
93 | <div id="TIME_AND_OTHER_GLOBAL_FUNCTIONS_CONT"> |
96 | <div id="TIME_REPRESENTATION_CONTENT"> |
94 | <p>Libev represents time as a single floating point number, representing the |
97 | <p>Libev represents time as a single floating point number, representing the |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
96 | the beginning of 1970, details are complicated, don't ask). This type is |
99 | the beginning of 1970, details are complicated, don't ask). This type is |
97 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
100 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
98 | to the double type in C.</p> |
101 | to the double type in C.</p> |
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102 | |
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103 | </div> |
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104 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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105 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
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106 | <p>These functions can be called anytime, even before initialising the |
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107 | library in any way.</p> |
99 | <dl> |
108 | <dl> |
100 | <dt>ev_tstamp ev_time ()</dt> |
109 | <dt>ev_tstamp ev_time ()</dt> |
101 | <dd> |
110 | <dd> |
102 | <p>Returns the current time as libev would use it.</p> |
111 | <p>Returns the current time as libev would use it.</p> |
103 | </dd> |
112 | </dd> |
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107 | <p>You can find out the major and minor version numbers of the library |
116 | <p>You can find out the major and minor version numbers of the library |
108 | you linked against by calling the functions <code>ev_version_major</code> and |
117 | you linked against by calling the functions <code>ev_version_major</code> and |
109 | <code>ev_version_minor</code>. If you want, you can compare against the global |
118 | <code>ev_version_minor</code>. If you want, you can compare against the global |
110 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
119 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
111 | version of the library your program was compiled against.</p> |
120 | version of the library your program was compiled against.</p> |
112 | <p>Usually, its a good idea to terminate if the major versions mismatch, |
121 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
113 | as this indicates an incompatible change. Minor versions are usually |
122 | as this indicates an incompatible change. Minor versions are usually |
114 | compatible to older versions, so a larger minor version alone is usually |
123 | compatible to older versions, so a larger minor version alone is usually |
115 | not a problem.</p> |
124 | not a problem.</p> |
116 | </dd> |
125 | </dd> |
117 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
126 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
118 | <dd> |
127 | <dd> |
119 | <p>Sets the allocation function to use (the prototype is similar to the |
128 | <p>Sets the allocation function to use (the prototype is similar to the |
120 | realloc function). It is used to allocate and free memory (no surprises |
129 | realloc C function, the semantics are identical). It is used to allocate |
121 | here). If it returns zero when memory needs to be allocated, the library |
130 | and free memory (no surprises here). If it returns zero when memory |
122 | might abort or take some potentially destructive action. The default is |
131 | needs to be allocated, the library might abort or take some potentially |
123 | your system realloc function.</p> |
132 | destructive action. The default is your system realloc function.</p> |
124 | <p>You could override this function in high-availability programs to, say, |
133 | <p>You could override this function in high-availability programs to, say, |
125 | free some memory if it cannot allocate memory, to use a special allocator, |
134 | free some memory if it cannot allocate memory, to use a special allocator, |
126 | or even to sleep a while and retry until some memory is available.</p> |
135 | or even to sleep a while and retry until some memory is available.</p> |
127 | </dd> |
136 | </dd> |
128 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
137 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
129 | <dd> |
138 | <dd> |
130 | <p>Set the callback function to call on a retryable syscall error (such |
139 | <p>Set the callback function to call on a retryable syscall error (such |
131 | as failed select, poll, epoll_wait). The message is a printable string |
140 | as failed select, poll, epoll_wait). The message is a printable string |
132 | indicating the system call or subsystem causing the problem. If this |
141 | indicating the system call or subsystem causing the problem. If this |
133 | callback is set, then libev will expect it to remedy the sitution, no |
142 | callback is set, then libev will expect it to remedy the sitution, no |
134 | matter what, when it returns. That is, libev will geenrally retry the |
143 | matter what, when it returns. That is, libev will generally retry the |
135 | requested operation, or, if the condition doesn't go away, do bad stuff |
144 | requested operation, or, if the condition doesn't go away, do bad stuff |
136 | (such as abort).</p> |
145 | (such as abort).</p> |
137 | </dd> |
146 | </dd> |
138 | </dl> |
147 | </dl> |
139 | |
148 | |
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142 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
151 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
143 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
152 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
144 | types of such loops, the <i>default</i> loop, which supports signals and child |
153 | types of such loops, the <i>default</i> loop, which supports signals and child |
145 | events, and dynamically created loops which do not.</p> |
154 | events, and dynamically created loops which do not.</p> |
146 | <p>If you use threads, a common model is to run the default event loop |
155 | <p>If you use threads, a common model is to run the default event loop |
147 | in your main thread (or in a separate thrad) and for each thread you |
156 | in your main thread (or in a separate thread) and for each thread you |
148 | create, you also create another event loop. Libev itself does no lockign |
157 | create, you also create another event loop. Libev itself does no locking |
149 | whatsoever, so if you mix calls to different event loops, make sure you |
158 | whatsoever, so if you mix calls to the same event loop in different |
150 | lock (this is usually a bad idea, though, even if done right).</p> |
159 | threads, make sure you lock (this is usually a bad idea, though, even if |
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160 | done correctly, because it's hideous and inefficient).</p> |
151 | <dl> |
161 | <dl> |
152 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
162 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
153 | <dd> |
163 | <dd> |
154 | <p>This will initialise the default event loop if it hasn't been initialised |
164 | <p>This will initialise the default event loop if it hasn't been initialised |
155 | yet and return it. If the default loop could not be initialised, returns |
165 | yet and return it. If the default loop could not be initialised, returns |
156 | false. If it already was initialised it simply returns it (and ignores the |
166 | false. If it already was initialised it simply returns it (and ignores the |
157 | flags).</p> |
167 | flags).</p> |
158 | <p>If you don't know what event loop to use, use the one returned from this |
168 | <p>If you don't know what event loop to use, use the one returned from this |
159 | function.</p> |
169 | function.</p> |
160 | <p>The flags argument can be used to specify special behaviour or specific |
170 | <p>The flags argument can be used to specify special behaviour or specific |
161 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO)</p> |
171 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p> |
162 | <p>It supports the following flags:</p> |
172 | <p>It supports the following flags:</p> |
163 | <p> |
173 | <p> |
164 | <dl> |
174 | <dl> |
165 | <dt>EVFLAG_AUTO</dt> |
175 | <dt><code>EVFLAG_AUTO</code></dt> |
166 | <dd> |
176 | <dd> |
167 | <p>The default flags value. Use this if you have no clue (its the right |
177 | <p>The default flags value. Use this if you have no clue (it's the right |
168 | thing, believe me).</p> |
178 | thing, believe me).</p> |
169 | </dd> |
179 | </dd> |
170 | <dt>EVFLAG_NOENV</dt> |
180 | <dt><code>EVFLAG_NOENV</code></dt> |
171 | <dd> |
181 | <dd> |
172 | <p>If this flag bit is ored into the flag value then libev will <i>not</i> look |
182 | <p>If this flag bit is ored into the flag value (or the program runs setuid |
173 | at the environment variable <code>LIBEV_FLAGS</code>. Otherwise (the default), this |
183 | or setgid) then libev will <i>not</i> look at the environment variable |
174 | environment variable will override the flags completely. This is useful |
184 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
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185 | override the flags completely if it is found in the environment. This is |
175 | to try out specific backends to tets their performance, or to work around |
186 | useful to try out specific backends to test their performance, or to work |
176 | bugs.</p> |
187 | around bugs.</p> |
177 | </dd> |
188 | </dd> |
178 | <dt>EVMETHOD_SELECT portable select backend</dt> |
189 | <dt><code>EVMETHOD_SELECT</code> (portable select backend)</dt> |
179 | <dt>EVMETHOD_POLL poll backend (everywhere except windows)</dt> |
190 | <dt><code>EVMETHOD_POLL</code> (poll backend, available everywhere except on windows)</dt> |
180 | <dt>EVMETHOD_EPOLL linux only</dt> |
191 | <dt><code>EVMETHOD_EPOLL</code> (linux only)</dt> |
181 | <dt>EVMETHOD_KQUEUE some bsds only</dt> |
192 | <dt><code>EVMETHOD_KQUEUE</code> (some bsds only)</dt> |
182 | <dt>EVMETHOD_DEVPOLL solaris 8 only</dt> |
193 | <dt><code>EVMETHOD_DEVPOLL</code> (solaris 8 only)</dt> |
183 | <dt>EVMETHOD_PORT solaris 10 only</dt> |
194 | <dt><code>EVMETHOD_PORT</code> (solaris 10 only)</dt> |
184 | <dd> |
195 | <dd> |
185 | <p>If one or more of these are ored into the flags value, then only these |
196 | <p>If one or more of these are ored into the flags value, then only these |
186 | backends will be tried (in the reverse order as given here). If one are |
197 | backends will be tried (in the reverse order as given here). If one are |
187 | specified, any backend will do.</p> |
198 | specified, any backend will do.</p> |
188 | </dd> |
199 | </dd> |
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198 | </dd> |
209 | </dd> |
199 | <dt>ev_default_destroy ()</dt> |
210 | <dt>ev_default_destroy ()</dt> |
200 | <dd> |
211 | <dd> |
201 | <p>Destroys the default loop again (frees all memory and kernel state |
212 | <p>Destroys the default loop again (frees all memory and kernel state |
202 | etc.). This stops all registered event watchers (by not touching them in |
213 | etc.). This stops all registered event watchers (by not touching them in |
203 | any way whatsoever, although you cnanot rely on this :).</p> |
214 | any way whatsoever, although you cannot rely on this :).</p> |
204 | </dd> |
215 | </dd> |
205 | <dt>ev_loop_destroy (loop)</dt> |
216 | <dt>ev_loop_destroy (loop)</dt> |
206 | <dd> |
217 | <dd> |
207 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
218 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
208 | earlier call to <code>ev_loop_new</code>.</p> |
219 | earlier call to <code>ev_loop_new</code>.</p> |
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214 | after forking, in either the parent or child process (or both, but that |
225 | after forking, in either the parent or child process (or both, but that |
215 | again makes little sense).</p> |
226 | again makes little sense).</p> |
216 | <p>You <i>must</i> call this function after forking if and only if you want to |
227 | <p>You <i>must</i> call this function after forking if and only if you want to |
217 | use the event library in both processes. If you just fork+exec, you don't |
228 | use the event library in both processes. If you just fork+exec, you don't |
218 | have to call it.</p> |
229 | have to call it.</p> |
219 | <p>The function itself is quite fast and its usually not a problem to call |
230 | <p>The function itself is quite fast and it's usually not a problem to call |
220 | it just in case after a fork. To make this easy, the function will fit in |
231 | it just in case after a fork. To make this easy, the function will fit in |
221 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
232 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
222 | <pre> pthread_atfork (0, 0, ev_default_fork); |
233 | <pre> pthread_atfork (0, 0, ev_default_fork); |
223 | |
234 | |
224 | </pre> |
235 | </pre> |
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232 | <dt>unsigned int ev_method (loop)</dt> |
243 | <dt>unsigned int ev_method (loop)</dt> |
233 | <dd> |
244 | <dd> |
234 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
245 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
235 | use.</p> |
246 | use.</p> |
236 | </dd> |
247 | </dd> |
237 | <dt>ev_tstamp = ev_now (loop)</dt> |
248 | <dt>ev_tstamp ev_now (loop)</dt> |
238 | <dd> |
249 | <dd> |
239 | <p>Returns the current "event loop time", which is the time the event loop |
250 | <p>Returns the current "event loop time", which is the time the event loop |
240 | got events and started processing them. This timestamp does not change |
251 | got events and started processing them. This timestamp does not change |
241 | as long as callbacks are being processed, and this is also the base time |
252 | as long as callbacks are being processed, and this is also the base time |
242 | used for relative timers. You can treat it as the timestamp of the event |
253 | used for relative timers. You can treat it as the timestamp of the event |
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249 | events.</p> |
260 | events.</p> |
250 | <p>If the flags argument is specified as 0, it will not return until either |
261 | <p>If the flags argument is specified as 0, it will not return until either |
251 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
262 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
252 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
263 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
253 | those events and any outstanding ones, but will not block your process in |
264 | those events and any outstanding ones, but will not block your process in |
254 | case there are no events.</p> |
265 | case there are no events and will return after one iteration of the loop.</p> |
255 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
266 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
256 | neccessary) and will handle those and any outstanding ones. It will block |
267 | neccessary) and will handle those and any outstanding ones. It will block |
257 | your process until at least one new event arrives.</p> |
268 | your process until at least one new event arrives, and will return after |
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269 | one iteration of the loop.</p> |
258 | <p>This flags value could be used to implement alternative looping |
270 | <p>This flags value could be used to implement alternative looping |
259 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
271 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
260 | more generic mechanism.</p> |
272 | more generic mechanism.</p> |
261 | </dd> |
273 | </dd> |
262 | <dt>ev_unloop (loop, how)</dt> |
274 | <dt>ev_unloop (loop, how)</dt> |
263 | <dd> |
275 | <dd> |
264 | <p>Can be used to make a call to <code>ev_loop</code> return early. The <code>how</code> argument |
276 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
|
|
277 | has processed all outstanding events). The <code>how</code> argument must be either |
265 | must be either <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> |
278 | <code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or |
266 | call return, or <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> |
279 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
267 | calls return.</p> |
|
|
268 | </dd> |
280 | </dd> |
269 | <dt>ev_ref (loop)</dt> |
281 | <dt>ev_ref (loop)</dt> |
270 | <dt>ev_unref (loop)</dt> |
282 | <dt>ev_unref (loop)</dt> |
271 | <dd> |
283 | <dd> |
272 | <p>Ref/unref can be used to add or remove a refcount on the event loop: Every |
284 | <p>Ref/unref can be used to add or remove a reference count on the event |
273 | watcher keeps one reference. If you have a long-runing watcher you never |
285 | loop: Every watcher keeps one reference, and as long as the reference |
274 | unregister that should not keep ev_loop from running, ev_unref() after |
286 | count is nonzero, <code>ev_loop</code> will not return on its own. If you have |
275 | starting, and ev_ref() before stopping it. Libev itself uses this for |
287 | a watcher you never unregister that should not keep <code>ev_loop</code> from |
276 | example for its internal signal pipe: It is not visible to you as a user |
288 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
277 | and should not keep <code>ev_loop</code> from exiting if the work is done. It is |
289 | example, libev itself uses this for its internal signal pipe: It is not |
278 | also an excellent way to do this for generic recurring timers or from |
290 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
279 | within third-party libraries. Just remember to unref after start and ref |
291 | no event watchers registered by it are active. It is also an excellent |
280 | before stop.</p> |
292 | way to do this for generic recurring timers or from within third-party |
|
|
293 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
281 | </dd> |
294 | </dd> |
282 | </dl> |
295 | </dl> |
283 | |
296 | |
284 | </div> |
297 | </div> |
285 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
298 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
286 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
299 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
287 | <p>A watcher is a structure that you create and register to record your |
300 | <p>A watcher is a structure that you create and register to record your |
288 | interest in some event. For instance, if you want to wait for STDIN to |
301 | interest in some event. For instance, if you want to wait for STDIN to |
289 | become readable, you would create an ev_io watcher for that:</p> |
302 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
290 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
303 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
291 | { |
304 | { |
292 | ev_io_stop (w); |
305 | ev_io_stop (w); |
293 | ev_unloop (loop, EVUNLOOP_ALL); |
306 | ev_unloop (loop, EVUNLOOP_ALL); |
294 | } |
307 | } |
… | |
… | |
318 | *)</code>), and you can stop watching for events at any time by calling the |
331 | *)</code>), and you can stop watching for events at any time by calling the |
319 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
332 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
320 | <p>As long as your watcher is active (has been started but not stopped) you |
333 | <p>As long as your watcher is active (has been started but not stopped) you |
321 | must not touch the values stored in it. Most specifically you must never |
334 | must not touch the values stored in it. Most specifically you must never |
322 | reinitialise it or call its set method.</p> |
335 | reinitialise it or call its set method.</p> |
323 | <p>You cna check whether an event is active by calling the <code>ev_is_active |
336 | <p>You can check whether an event is active by calling the <code>ev_is_active |
324 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
337 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
325 | callback for it has not been called yet) you cna use the <code>ev_is_pending |
338 | callback for it has not been called yet) you can use the <code>ev_is_pending |
326 | (watcher *)</code> macro.</p> |
339 | (watcher *)</code> macro.</p> |
327 | <p>Each and every callback receives the event loop pointer as first, the |
340 | <p>Each and every callback receives the event loop pointer as first, the |
328 | registered watcher structure as second, and a bitset of received events as |
341 | registered watcher structure as second, and a bitset of received events as |
329 | third argument.</p> |
342 | third argument.</p> |
330 | <p>The rceeived events usually include a single bit per event type received |
343 | <p>The received events usually include a single bit per event type received |
331 | (you can receive multiple events at the same time). The possible bit masks |
344 | (you can receive multiple events at the same time). The possible bit masks |
332 | are:</p> |
345 | are:</p> |
333 | <dl> |
346 | <dl> |
334 | <dt>EV_READ</dt> |
347 | <dt><code>EV_READ</code></dt> |
335 | <dt>EV_WRITE</dt> |
348 | <dt><code>EV_WRITE</code></dt> |
336 | <dd> |
349 | <dd> |
337 | <p>The file descriptor in the ev_io watcher has become readable and/or |
350 | <p>The file descriptor in the <code>ev_io</code> watcher has become readable and/or |
338 | writable.</p> |
351 | writable.</p> |
339 | </dd> |
352 | </dd> |
340 | <dt>EV_TIMEOUT</dt> |
353 | <dt><code>EV_TIMEOUT</code></dt> |
341 | <dd> |
|
|
342 | <p>The ev_timer watcher has timed out.</p> |
|
|
343 | </dd> |
354 | <dd> |
344 | <dt>EV_PERIODIC</dt> |
355 | <p>The <code>ev_timer</code> watcher has timed out.</p> |
345 | <dd> |
356 | </dd> |
346 | <p>The ev_periodic watcher has timed out.</p> |
357 | <dt><code>EV_PERIODIC</code></dt> |
347 | </dd> |
358 | <dd> |
348 | <dt>EV_SIGNAL</dt> |
359 | <p>The <code>ev_periodic</code> watcher has timed out.</p> |
349 | <dd> |
360 | </dd> |
|
|
361 | <dt><code>EV_SIGNAL</code></dt> |
|
|
362 | <dd> |
350 | <p>The signal specified in the ev_signal watcher has been received by a thread.</p> |
363 | <p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p> |
351 | </dd> |
|
|
352 | <dt>EV_CHILD</dt> |
|
|
353 | <dd> |
364 | </dd> |
|
|
365 | <dt><code>EV_CHILD</code></dt> |
|
|
366 | <dd> |
354 | <p>The pid specified in the ev_child watcher has received a status change.</p> |
367 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
355 | </dd> |
|
|
356 | <dt>EV_IDLE</dt> |
|
|
357 | <dd> |
368 | </dd> |
|
|
369 | <dt><code>EV_IDLE</code></dt> |
|
|
370 | <dd> |
358 | <p>The ev_idle watcher has determined that you have nothing better to do.</p> |
371 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
359 | </dd> |
|
|
360 | <dt>EV_PREPARE</dt> |
|
|
361 | <dt>EV_CHECK</dt> |
|
|
362 | <dd> |
372 | </dd> |
|
|
373 | <dt><code>EV_PREPARE</code></dt> |
|
|
374 | <dt><code>EV_CHECK</code></dt> |
|
|
375 | <dd> |
363 | <p>All ev_prepare watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
376 | <p>All <code>ev_prepare</code> watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
364 | to gather new events, and all ev_check watchers are invoked just after |
377 | to gather new events, and all <code>ev_check</code> watchers are invoked just after |
365 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
378 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
366 | received events. Callbacks of both watcher types can start and stop as |
379 | received events. Callbacks of both watcher types can start and stop as |
367 | many watchers as they want, and all of them will be taken into account |
380 | many watchers as they want, and all of them will be taken into account |
368 | (for example, a ev_prepare watcher might start an idle watcher to keep |
381 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
369 | <code>ev_loop</code> from blocking).</p> |
382 | <code>ev_loop</code> from blocking).</p> |
370 | </dd> |
383 | </dd> |
371 | <dt>EV_ERROR</dt> |
384 | <dt><code>EV_ERROR</code></dt> |
372 | <dd> |
385 | <dd> |
373 | <p>An unspecified error has occured, the watcher has been stopped. This might |
386 | <p>An unspecified error has occured, the watcher has been stopped. This might |
374 | happen because the watcher could not be properly started because libev |
387 | happen because the watcher could not be properly started because libev |
375 | ran out of memory, a file descriptor was found to be closed or any other |
388 | ran out of memory, a file descriptor was found to be closed or any other |
376 | problem. You best act on it by reporting the problem and somehow coping |
389 | problem. You best act on it by reporting the problem and somehow coping |
… | |
… | |
385 | |
398 | |
386 | </div> |
399 | </div> |
387 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
400 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
388 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
401 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
389 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
402 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
390 | and read at any time, libev will completely ignore it. This cna be used |
403 | and read at any time, libev will completely ignore it. This can be used |
391 | to associate arbitrary data with your watcher. If you need more data and |
404 | to associate arbitrary data with your watcher. If you need more data and |
392 | don't want to allocate memory and store a pointer to it in that data |
405 | don't want to allocate memory and store a pointer to it in that data |
393 | member, you can also "subclass" the watcher type and provide your own |
406 | member, you can also "subclass" the watcher type and provide your own |
394 | data:</p> |
407 | data:</p> |
395 | <pre> struct my_io |
408 | <pre> struct my_io |
… | |
… | |
422 | <div id="WATCHER_TYPES_CONTENT"> |
435 | <div id="WATCHER_TYPES_CONTENT"> |
423 | <p>This section describes each watcher in detail, but will not repeat |
436 | <p>This section describes each watcher in detail, but will not repeat |
424 | information given in the last section.</p> |
437 | information given in the last section.</p> |
425 | |
438 | |
426 | </div> |
439 | </div> |
427 | <h2 id="struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</h2> |
440 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
428 | <div id="struct_ev_io_is_my_file_descriptor_r-2"> |
441 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
429 | <p>I/O watchers check whether a file descriptor is readable or writable |
442 | <p>I/O watchers check whether a file descriptor is readable or writable |
430 | in each iteration of the event loop (This behaviour is called |
443 | in each iteration of the event loop (This behaviour is called |
431 | level-triggering because you keep receiving events as long as the |
444 | level-triggering because you keep receiving events as long as the |
432 | condition persists. Remember you cna stop the watcher if you don't want to |
445 | condition persists. Remember you can stop the watcher if you don't want to |
433 | act on the event and neither want to receive future events).</p> |
446 | act on the event and neither want to receive future events).</p> |
|
|
447 | <p>In general you can register as many read and/or write event watchers per |
|
|
448 | fd as you want (as long as you don't confuse yourself). Setting all file |
|
|
449 | descriptors to non-blocking mode is also usually a good idea (but not |
|
|
450 | required if you know what you are doing).</p> |
|
|
451 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
452 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
453 | descriptors correctly if you register interest in two or more fds pointing |
|
|
454 | to the same underlying file/socket etc. description (that is, they share |
|
|
455 | the same underlying "file open").</p> |
|
|
456 | <p>If you must do this, then force the use of a known-to-be-good backend |
|
|
457 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
|
|
458 | EVMETHOD_POLL).</p> |
434 | <dl> |
459 | <dl> |
435 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
460 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
436 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
461 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
437 | <dd> |
462 | <dd> |
438 | <p>Configures an ev_io watcher. The fd is the file descriptor to rceeive |
463 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
439 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
464 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
440 | EV_WRITE</code> to receive the given events.</p> |
465 | EV_WRITE</code> to receive the given events.</p> |
441 | </dd> |
466 | </dd> |
442 | </dl> |
467 | </dl> |
443 | |
468 | |
444 | </div> |
469 | </div> |
445 | <h2 id="struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</h2> |
470 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
446 | <div id="struct_ev_timer_relative_and_optiona-2"> |
471 | <div id="code_ev_timer_code_relative_and_opti-2"> |
447 | <p>Timer watchers are simple relative timers that generate an event after a |
472 | <p>Timer watchers are simple relative timers that generate an event after a |
448 | given time, and optionally repeating in regular intervals after that.</p> |
473 | given time, and optionally repeating in regular intervals after that.</p> |
449 | <p>The timers are based on real time, that is, if you register an event that |
474 | <p>The timers are based on real time, that is, if you register an event that |
450 | times out after an hour and youreset your system clock to last years |
475 | times out after an hour and you reset your system clock to last years |
451 | time, it will still time out after (roughly) and hour. "Roughly" because |
476 | time, it will still time out after (roughly) and hour. "Roughly" because |
452 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
477 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
453 | monotonic clock option helps a lot here).</p> |
478 | monotonic clock option helps a lot here).</p> |
|
|
479 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
|
|
480 | time. This is usually the right thing as this timestamp refers to the time |
|
|
481 | of the event triggering whatever timeout you are modifying/starting. If |
|
|
482 | you suspect event processing to be delayed and you *need* to base the timeout |
|
|
483 | on the current time, use something like this to adjust for this:</p> |
|
|
484 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
485 | |
|
|
486 | </pre> |
454 | <dl> |
487 | <dl> |
455 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
488 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
456 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
489 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
457 | <dd> |
490 | <dd> |
458 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
491 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
460 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
493 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
461 | later, again, and again, until stopped manually.</p> |
494 | later, again, and again, until stopped manually.</p> |
462 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
495 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
463 | configure a timer to trigger every 10 seconds, then it will trigger at |
496 | configure a timer to trigger every 10 seconds, then it will trigger at |
464 | exactly 10 second intervals. If, however, your program cannot keep up with |
497 | exactly 10 second intervals. If, however, your program cannot keep up with |
465 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
498 | the timer (because it takes longer than those 10 seconds to do stuff) the |
466 | timer will not fire more than once per event loop iteration.</p> |
499 | timer will not fire more than once per event loop iteration.</p> |
467 | </dd> |
500 | </dd> |
468 | <dt>ev_timer_again (loop)</dt> |
501 | <dt>ev_timer_again (loop)</dt> |
469 | <dd> |
502 | <dd> |
470 | <p>This will act as if the timer timed out and restart it again if it is |
503 | <p>This will act as if the timer timed out and restart it again if it is |
… | |
… | |
474 | value), or reset the running timer to the repeat value.</p> |
507 | value), or reset the running timer to the repeat value.</p> |
475 | <p>This sounds a bit complicated, but here is a useful and typical |
508 | <p>This sounds a bit complicated, but here is a useful and typical |
476 | example: Imagine you have a tcp connection and you want a so-called idle |
509 | example: Imagine you have a tcp connection and you want a so-called idle |
477 | timeout, that is, you want to be called when there have been, say, 60 |
510 | timeout, that is, you want to be called when there have been, say, 60 |
478 | seconds of inactivity on the socket. The easiest way to do this is to |
511 | seconds of inactivity on the socket. The easiest way to do this is to |
479 | configure an ev_timer with after=repeat=60 and calling ev_timer_again each |
512 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
480 | time you successfully read or write some data. If you go into an idle |
513 | time you successfully read or write some data. If you go into an idle |
481 | state where you do not expect data to travel on the socket, you can stop |
514 | state where you do not expect data to travel on the socket, you can stop |
482 | the timer, and again will automatically restart it if need be.</p> |
515 | the timer, and again will automatically restart it if need be.</p> |
483 | </dd> |
516 | </dd> |
484 | </dl> |
517 | </dl> |
485 | |
518 | |
486 | </div> |
519 | </div> |
487 | <h2 id="ev_periodic_to_cron_or_not_to_cron_i">ev_periodic - to cron or not to cron it</h2> |
520 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
488 | <div id="ev_periodic_to_cron_or_not_to_cron_i-2"> |
521 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
489 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
522 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
490 | (and unfortunately a bit complex).</p> |
523 | (and unfortunately a bit complex).</p> |
491 | <p>Unlike ev_timer's, they are not based on real time (or relative time) |
524 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
492 | but on wallclock time (absolute time). You can tell a periodic watcher |
525 | but on wallclock time (absolute time). You can tell a periodic watcher |
493 | to trigger "at" some specific point in time. For example, if you tell a |
526 | to trigger "at" some specific point in time. For example, if you tell a |
494 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
527 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
495 | + 10.>) and then reset your system clock to the last year, then it will |
528 | + 10.>) and then reset your system clock to the last year, then it will |
496 | take a year to trigger the event (unlike an ev_timer, which would trigger |
529 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
497 | roughly 10 seconds later and of course not if you reset your system time |
530 | roughly 10 seconds later and of course not if you reset your system time |
498 | again).</p> |
531 | again).</p> |
499 | <p>They can also be used to implement vastly more complex timers, such as |
532 | <p>They can also be used to implement vastly more complex timers, such as |
500 | triggering an event on eahc midnight, local time.</p> |
533 | triggering an event on eahc midnight, local time.</p> |
501 | <dl> |
534 | <dl> |
… | |
… | |
527 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
560 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
528 | |
561 | |
529 | </pre> |
562 | </pre> |
530 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
563 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
531 | but only that the the callback will be called when the system time shows a |
564 | but only that the the callback will be called when the system time shows a |
532 | full hour (UTC), or more correct, when the system time is evenly divisible |
565 | full hour (UTC), or more correctly, when the system time is evenly divisible |
533 | by 3600.</p> |
566 | by 3600.</p> |
534 | <p>Another way to think about it (for the mathematically inclined) is that |
567 | <p>Another way to think about it (for the mathematically inclined) is that |
535 | ev_periodic will try to run the callback in this mode at the next possible |
568 | <code>ev_periodic</code> will try to run the callback in this mode at the next possible |
536 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
569 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
537 | </dd> |
570 | </dd> |
538 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
571 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
539 | <dd> |
572 | <dd> |
540 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
573 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
541 | ignored. Instead, each time the periodic watcher gets scheduled, the |
574 | ignored. Instead, each time the periodic watcher gets scheduled, the |
542 | reschedule callback will be called with the watcher as first, and the |
575 | reschedule callback will be called with the watcher as first, and the |
543 | current time as second argument.</p> |
576 | current time as second argument.</p> |
544 | <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other |
577 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
545 | periodic watcher, ever, or make any event loop modificstions</i>. If you need |
578 | ever, or make any event loop modifications</i>. If you need to stop it, |
546 | to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards.</p> |
579 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
580 | starting a prepare watcher).</p> |
547 | <p>Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
581 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
548 | ev_tstamp now)>, e.g.:</p> |
582 | ev_tstamp now)</code>, e.g.:</p> |
549 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
583 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
550 | { |
584 | { |
551 | return now + 60.; |
585 | return now + 60.; |
552 | } |
586 | } |
553 | |
587 | |
554 | </pre> |
588 | </pre> |
555 | <p>It must return the next time to trigger, based on the passed time value |
589 | <p>It must return the next time to trigger, based on the passed time value |
556 | (that is, the lowest time value larger than to the second argument). It |
590 | (that is, the lowest time value larger than to the second argument). It |
557 | will usually be called just before the callback will be triggered, but |
591 | will usually be called just before the callback will be triggered, but |
558 | might be called at other times, too.</p> |
592 | might be called at other times, too.</p> |
|
|
593 | <p>NOTE: <i>This callback must always return a time that is later than the |
|
|
594 | passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p> |
559 | <p>This can be used to create very complex timers, such as a timer that |
595 | <p>This can be used to create very complex timers, such as a timer that |
560 | triggers on each midnight, local time. To do this, you would calculate the |
596 | triggers on each midnight, local time. To do this, you would calculate the |
561 | next midnight after <code>now</code> and return the timestamp value for this. How you do this |
597 | next midnight after <code>now</code> and return the timestamp value for this. How |
562 | is, again, up to you (but it is not trivial).</p> |
598 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
599 | reason I omitted it as an example).</p> |
563 | </dd> |
600 | </dd> |
564 | </dl> |
601 | </dl> |
565 | </p> |
602 | </p> |
566 | </dd> |
603 | </dd> |
567 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
604 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
… | |
… | |
572 | program when the crontabs have changed).</p> |
609 | program when the crontabs have changed).</p> |
573 | </dd> |
610 | </dd> |
574 | </dl> |
611 | </dl> |
575 | |
612 | |
576 | </div> |
613 | </div> |
577 | <h2 id="ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</h2> |
614 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
578 | <div id="ev_signal_signal_me_when_a_signal_ge-2"> |
615 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
579 | <p>Signal watchers will trigger an event when the process receives a specific |
616 | <p>Signal watchers will trigger an event when the process receives a specific |
580 | signal one or more times. Even though signals are very asynchronous, libev |
617 | signal one or more times. Even though signals are very asynchronous, libev |
581 | will try its best to deliver signals synchronously, i.e. as part of the |
618 | will try it's best to deliver signals synchronously, i.e. as part of the |
582 | normal event processing, like any other event.</p> |
619 | normal event processing, like any other event.</p> |
583 | <p>You cna configure as many watchers as you like per signal. Only when the |
620 | <p>You can configure as many watchers as you like per signal. Only when the |
584 | first watcher gets started will libev actually register a signal watcher |
621 | first watcher gets started will libev actually register a signal watcher |
585 | with the kernel (thus it coexists with your own signal handlers as long |
622 | with the kernel (thus it coexists with your own signal handlers as long |
586 | as you don't register any with libev). Similarly, when the last signal |
623 | as you don't register any with libev). Similarly, when the last signal |
587 | watcher for a signal is stopped libev will reset the signal handler to |
624 | watcher for a signal is stopped libev will reset the signal handler to |
588 | SIG_DFL (regardless of what it was set to before).</p> |
625 | SIG_DFL (regardless of what it was set to before).</p> |
… | |
… | |
594 | of the <code>SIGxxx</code> constants).</p> |
631 | of the <code>SIGxxx</code> constants).</p> |
595 | </dd> |
632 | </dd> |
596 | </dl> |
633 | </dl> |
597 | |
634 | |
598 | </div> |
635 | </div> |
599 | <h2 id="ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</h2> |
636 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
600 | <div id="ev_child_wait_for_pid_status_changes-2"> |
637 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
601 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
638 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
602 | some child status changes (most typically when a child of yours dies).</p> |
639 | some child status changes (most typically when a child of yours dies).</p> |
603 | <dl> |
640 | <dl> |
604 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
641 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
605 | <dt>ev_child_set (ev_child *, int pid)</dt> |
642 | <dt>ev_child_set (ev_child *, int pid)</dt> |
606 | <dd> |
643 | <dd> |
607 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
644 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
608 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
645 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
609 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
646 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
610 | the status word (use the macros from <code>sys/wait.h</code>). The <code>rpid</code> member |
647 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
|
|
648 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
611 | contains the pid of the process causing the status change.</p> |
649 | process causing the status change.</p> |
612 | </dd> |
650 | </dd> |
613 | </dl> |
651 | </dl> |
614 | |
652 | |
615 | </div> |
653 | </div> |
616 | <h2 id="ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</h2> |
654 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
617 | <div id="ev_idle_when_you_ve_got_nothing_bett-2"> |
655 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
618 | <p>Idle watchers trigger events when there are no other I/O or timer (or |
656 | <p>Idle watchers trigger events when there are no other events are pending |
619 | periodic) events pending. That is, as long as your process is busy |
657 | (prepare, check and other idle watchers do not count). That is, as long |
620 | handling sockets or timeouts it will not be called. But when your process |
658 | as your process is busy handling sockets or timeouts (or even signals, |
621 | is idle all idle watchers are being called again and again - until |
659 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
660 | watchers are being called again and again, once per event loop iteration - |
622 | stopped, that is, or your process receives more events.</p> |
661 | until stopped, that is, or your process receives more events and becomes |
|
|
662 | busy.</p> |
623 | <p>The most noteworthy effect is that as long as any idle watchers are |
663 | <p>The most noteworthy effect is that as long as any idle watchers are |
624 | active, the process will not block when waiting for new events.</p> |
664 | active, the process will not block when waiting for new events.</p> |
625 | <p>Apart from keeping your process non-blocking (which is a useful |
665 | <p>Apart from keeping your process non-blocking (which is a useful |
626 | effect on its own sometimes), idle watchers are a good place to do |
666 | effect on its own sometimes), idle watchers are a good place to do |
627 | "pseudo-background processing", or delay processing stuff to after the |
667 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
634 | believe me.</p> |
674 | believe me.</p> |
635 | </dd> |
675 | </dd> |
636 | </dl> |
676 | </dl> |
637 | |
677 | |
638 | </div> |
678 | </div> |
639 | <h2 id="prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</h2> |
679 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
640 | <div id="prepare_and_check_your_hooks_into_th-2"> |
680 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
641 | <p>Prepare and check watchers usually (but not always) are used in |
681 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
642 | tandom. Prepare watchers get invoked before the process blocks and check |
682 | prepare watchers get invoked before the process blocks and check watchers |
643 | watchers afterwards.</p> |
683 | afterwards.</p> |
644 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
684 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
645 | could be used, for example, to track variable changes, implement your own |
685 | could be used, for example, to track variable changes, implement your own |
646 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
686 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
647 | <p>This is done by examining in each prepare call which file descriptors need |
687 | <p>This is done by examining in each prepare call which file descriptors need |
648 | to be watched by the other library, registering ev_io watchers for them |
688 | to be watched by the other library, registering <code>ev_io</code> watchers for |
649 | and starting an ev_timer watcher for any timeouts (many libraries provide |
689 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
650 | just this functionality). Then, in the check watcher you check for any |
690 | provide just this functionality). Then, in the check watcher you check for |
651 | events that occured (by making your callbacks set soem flags for example) |
691 | any events that occured (by checking the pending status of all watchers |
652 | and call back into the library.</p> |
692 | and stopping them) and call back into the library. The I/O and timer |
|
|
693 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
694 | because you never know, you know?).</p> |
653 | <p>As another example, the perl Coro module uses these hooks to integrate |
695 | <p>As another example, the Perl Coro module uses these hooks to integrate |
654 | coroutines into libev programs, by yielding to other active coroutines |
696 | coroutines into libev programs, by yielding to other active coroutines |
655 | during each prepare and only letting the process block if no coroutines |
697 | during each prepare and only letting the process block if no coroutines |
656 | are ready to run.</p> |
698 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
699 | with priority higher than or equal to the event loop and one coroutine |
|
|
700 | of lower priority, but only once, using idle watchers to keep the event |
|
|
701 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
702 | low-priority coroutines to idle/background tasks).</p> |
657 | <dl> |
703 | <dl> |
658 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
704 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
659 | <dt>ev_check_init (ev_check *, callback)</dt> |
705 | <dt>ev_check_init (ev_check *, callback)</dt> |
660 | <dd> |
706 | <dd> |
661 | <p>Initialises and configures the prepare or check watcher - they have no |
707 | <p>Initialises and configures the prepare or check watcher - they have no |
662 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
708 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
663 | macros, but using them is utterly, utterly pointless.</p> |
709 | macros, but using them is utterly, utterly and completely pointless.</p> |
664 | </dd> |
710 | </dd> |
665 | </dl> |
711 | </dl> |
666 | |
712 | |
667 | </div> |
713 | </div> |
668 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
714 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
669 | <div id="OTHER_FUNCTIONS_CONTENT"> |
715 | <div id="OTHER_FUNCTIONS_CONTENT"> |
670 | <p>There are some other fucntions of possible interest. Described. Here. Now.</p> |
716 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
671 | <dl> |
717 | <dl> |
672 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
718 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
673 | <dd> |
719 | <dd> |
674 | <p>This function combines a simple timer and an I/O watcher, calls your |
720 | <p>This function combines a simple timer and an I/O watcher, calls your |
675 | callback on whichever event happens first and automatically stop both |
721 | callback on whichever event happens first and automatically stop both |
676 | watchers. This is useful if you want to wait for a single event on an fd |
722 | watchers. This is useful if you want to wait for a single event on an fd |
677 | or timeout without havign to allocate/configure/start/stop/free one or |
723 | or timeout without having to allocate/configure/start/stop/free one or |
678 | more watchers yourself.</p> |
724 | more watchers yourself.</p> |
679 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events is |
725 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events |
680 | ignored. Otherwise, an ev_io watcher for the given <code>fd</code> and <code>events</code> set |
726 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
681 | will be craeted and started.</p> |
727 | <code>events</code> set will be craeted and started.</p> |
682 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
728 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
683 | started. Otherwise an ev_timer watcher with after = <code>timeout</code> (and repeat |
729 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
684 | = 0) will be started.</p> |
730 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
|
|
731 | dubious value.</p> |
685 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and |
732 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets |
686 | gets passed an events set (normally a combination of EV_ERROR, EV_READ, |
733 | passed an <code>revents</code> set like normal event callbacks (a combination of |
687 | EV_WRITE or EV_TIMEOUT) and the <code>arg</code> value passed to <code>ev_once</code>:</p> |
734 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
|
|
735 | value passed to <code>ev_once</code>:</p> |
688 | <pre> static void stdin_ready (int revents, void *arg) |
736 | <pre> static void stdin_ready (int revents, void *arg) |
689 | { |
737 | { |
690 | if (revents & EV_TIMEOUT) |
738 | if (revents & EV_TIMEOUT) |
691 | /* doh, nothing entered */ |
739 | /* doh, nothing entered */; |
692 | else if (revents & EV_READ) |
740 | else if (revents & EV_READ) |
693 | /* stdin might have data for us, joy! */ |
741 | /* stdin might have data for us, joy! */; |
694 | } |
742 | } |
695 | |
743 | |
696 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
744 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
697 | |
745 | |
698 | </pre> |
746 | </pre> |
699 | </dd> |
747 | </dd> |
700 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
748 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
701 | <dd> |
749 | <dd> |
702 | <p>Feeds the given event set into the event loop, as if the specified event |
750 | <p>Feeds the given event set into the event loop, as if the specified event |
703 | has happened for the specified watcher (which must be a pointer to an |
751 | had happened for the specified watcher (which must be a pointer to an |
704 | initialised but not necessarily active event watcher).</p> |
752 | initialised but not necessarily started event watcher).</p> |
705 | </dd> |
753 | </dd> |
706 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
754 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
707 | <dd> |
755 | <dd> |
708 | <p>Feed an event on the given fd, as if a file descriptor backend detected it.</p> |
756 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
|
|
757 | the given events it.</p> |
709 | </dd> |
758 | </dd> |
710 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
759 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
711 | <dd> |
760 | <dd> |
712 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
761 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
713 | </dd> |
762 | </dd> |
714 | </dl> |
763 | </dl> |
|
|
764 | |
|
|
765 | </div> |
|
|
766 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
767 | <div id="LIBEVENT_EMULATION_CONTENT"> |
|
|
768 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
769 | emulate the internals of libevent, so here are some usage hints:</p> |
|
|
770 | <dl> |
|
|
771 | <dt>* Use it by including <event.h>, as usual.</dt> |
|
|
772 | <dt>* The following members are fully supported: ev_base, ev_callback, |
|
|
773 | ev_arg, ev_fd, ev_res, ev_events.</dt> |
|
|
774 | <dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
775 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
776 | it a private API).</dt> |
|
|
777 | <dt>* Priorities are not currently supported. Initialising priorities |
|
|
778 | will fail and all watchers will have the same priority, even though there |
|
|
779 | is an ev_pri field.</dt> |
|
|
780 | <dt>* Other members are not supported.</dt> |
|
|
781 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
|
|
782 | to use the libev header file and library.</dt> |
|
|
783 | </dl> |
|
|
784 | |
|
|
785 | </div> |
|
|
786 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
787 | <div id="C_SUPPORT_CONTENT"> |
|
|
788 | <p>TBD.</p> |
715 | |
789 | |
716 | </div> |
790 | </div> |
717 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
791 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
718 | <div id="AUTHOR_CONTENT"> |
792 | <div id="AUTHOR_CONTENT"> |
719 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
793 | <p>Marc Lehmann <libev@schmorp.de>.</p> |