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4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
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9 | <meta name="created" content="Mon Nov 12 09:29:10 2007" /> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
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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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. Please note that the |
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112 | <code>ev_now</code> function is usually faster and also often returns the timestamp |
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113 | you actually want to know.</p> |
103 | </dd> |
114 | </dd> |
104 | <dt>int ev_version_major ()</dt> |
115 | <dt>int ev_version_major ()</dt> |
105 | <dt>int ev_version_minor ()</dt> |
116 | <dt>int ev_version_minor ()</dt> |
106 | <dd> |
117 | <dd> |
107 | <p>You can find out the major and minor version numbers of the library |
118 | <p>You can find out the major and minor version numbers of the library |
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112 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
123 | <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 |
124 | as this indicates an incompatible change. Minor versions are usually |
114 | compatible to older versions, so a larger minor version alone is usually |
125 | compatible to older versions, so a larger minor version alone is usually |
115 | not a problem.</p> |
126 | not a problem.</p> |
116 | </dd> |
127 | </dd> |
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128 | <dt>unsigned int ev_supported_backends ()</dt> |
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129 | <dd> |
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130 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
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131 | value) compiled into this binary of libev (independent of their |
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132 | availability on the system you are running on). See <code>ev_default_loop</code> for |
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133 | a description of the set values.</p> |
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134 | </dd> |
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135 | <dt>unsigned int ev_recommended_backends ()</dt> |
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136 | <dd> |
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137 | <p>Return the set of all backends compiled into this binary of libev and also |
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138 | recommended for this platform. This set is often smaller than the one |
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139 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
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140 | most BSDs and will not be autodetected unless you explicitly request it |
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141 | (assuming you know what you are doing). This is the set of backends that |
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142 | <code>EVFLAG_AUTO</code> will probe for.</p> |
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143 | </dd> |
117 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
144 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
118 | <dd> |
145 | <dd> |
119 | <p>Sets the allocation function to use (the prototype is similar to the |
146 | <p>Sets the allocation function to use (the prototype is similar to the |
120 | realloc C function, the semantics are identical). It is used to allocate |
147 | realloc C function, the semantics are identical). It is used to allocate |
121 | and free memory (no surprises here). If it returns zero when memory |
148 | and free memory (no surprises here). If it returns zero when memory |
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142 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
169 | <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 |
170 | <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 |
171 | types of such loops, the <i>default</i> loop, which supports signals and child |
145 | events, and dynamically created loops which do not.</p> |
172 | 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 |
173 | <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 |
174 | 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 locking |
175 | create, you also create another event loop. Libev itself does no locking |
149 | whatsoever, so if you mix calls to the same event loop in different |
176 | whatsoever, so if you mix calls to the same event loop in different |
150 | threads, make sure you lock (this is usually a bad idea, though, even if |
177 | threads, make sure you lock (this is usually a bad idea, though, even if |
151 | done correctly, because it's hideous and inefficient).</p> |
178 | done correctly, because it's hideous and inefficient).</p> |
152 | <dl> |
179 | <dl> |
153 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
180 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
154 | <dd> |
181 | <dd> |
155 | <p>This will initialise the default event loop if it hasn't been initialised |
182 | <p>This will initialise the default event loop if it hasn't been initialised |
156 | yet and return it. If the default loop could not be initialised, returns |
183 | yet and return it. If the default loop could not be initialised, returns |
157 | false. If it already was initialised it simply returns it (and ignores the |
184 | false. If it already was initialised it simply returns it (and ignores the |
158 | flags).</p> |
185 | flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p> |
159 | <p>If you don't know what event loop to use, use the one returned from this |
186 | <p>If you don't know what event loop to use, use the one returned from this |
160 | function.</p> |
187 | function.</p> |
161 | <p>The flags argument can be used to specify special behaviour or specific |
188 | <p>The flags argument can be used to specify special behaviour or specific |
162 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p> |
189 | backends to use, and is usually specified as <code>0</code> (or EVFLAG_AUTO).</p> |
163 | <p>It supports the following flags:</p> |
190 | <p>It supports the following flags:</p> |
164 | <p> |
191 | <p> |
165 | <dl> |
192 | <dl> |
166 | <dt>EVFLAG_AUTO</dt> |
193 | <dt><code>EVFLAG_AUTO</code></dt> |
167 | <dd> |
194 | <dd> |
168 | <p>The default flags value. Use this if you have no clue (it's the right |
195 | <p>The default flags value. Use this if you have no clue (it's the right |
169 | thing, believe me).</p> |
196 | thing, believe me).</p> |
170 | </dd> |
197 | </dd> |
171 | <dt>EVFLAG_NOENV</dt> |
198 | <dt><code>EVFLAG_NOENV</code></dt> |
172 | <dd> |
199 | <dd> |
173 | <p>If this flag bit is ored into the flag value (or the program runs setuid |
200 | <p>If this flag bit is ored into the flag value (or the program runs setuid |
174 | or setgid) then libev will <i>not</i> look at the environment variable |
201 | or setgid) then libev will <i>not</i> look at the environment variable |
175 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
202 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
176 | override the flags completely if it is found in the environment. This is |
203 | override the flags completely if it is found in the environment. This is |
177 | useful to try out specific backends to test their performance, or to work |
204 | useful to try out specific backends to test their performance, or to work |
178 | around bugs.</p> |
205 | around bugs.</p> |
179 | </dd> |
206 | </dd> |
180 | <dt>EVMETHOD_SELECT (portable select backend)</dt> |
207 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
181 | <dt>EVMETHOD_POLL (poll backend, available everywhere except on windows)</dt> |
208 | <dd> |
182 | <dt>EVMETHOD_EPOLL (linux only)</dt> |
209 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
183 | <dt>EVMETHOD_KQUEUE (some bsds only)</dt> |
210 | libev tries to roll its own fd_set with no limits on the number of fds, |
184 | <dt>EVMETHOD_DEVPOLL (solaris 8 only)</dt> |
211 | but if that fails, expect a fairly low limit on the number of fds when |
185 | <dt>EVMETHOD_PORT (solaris 10 only)</dt> |
212 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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213 | the fastest backend for a low number of fds.</p> |
186 | <dd> |
214 | </dd> |
187 | <p>If one or more of these are ored into the flags value, then only these |
215 | <dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
188 | backends will be tried (in the reverse order as given here). If one are |
216 | <dd> |
189 | specified, any backend will do.</p> |
217 | <p>And this is your standard poll(2) backend. It's more complicated than |
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218 | select, but handles sparse fds better and has no artificial limit on the |
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219 | number of fds you can use (except it will slow down considerably with a |
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220 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
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221 | </dd> |
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222 | <dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt> |
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223 | <dd> |
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224 | <p>For few fds, this backend is a bit little slower than poll and select, |
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225 | but it scales phenomenally better. While poll and select usually scale like |
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226 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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227 | either O(1) or O(active_fds).</p> |
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228 | <p>While stopping and starting an I/O watcher in the same iteration will |
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229 | result in some caching, there is still a syscall per such incident |
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230 | (because the fd could point to a different file description now), so its |
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231 | best to avoid that. Also, dup()ed file descriptors might not work very |
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232 | well if you register events for both fds.</p> |
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233 | <p>Please note that epoll sometimes generates spurious notifications, so you |
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234 | need to use non-blocking I/O or other means to avoid blocking when no data |
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235 | (or space) is available.</p> |
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236 | </dd> |
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237 | <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> |
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238 | <dd> |
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239 | <p>Kqueue deserves special mention, as at the time of this writing, it |
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240 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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241 | anything but sockets and pipes, except on Darwin, where of course its |
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242 | completely useless). For this reason its not being "autodetected" unless |
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243 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).</p> |
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244 | <p>It scales in the same way as the epoll backend, but the interface to the |
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245 | kernel is more efficient (which says nothing about its actual speed, of |
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246 | course). While starting and stopping an I/O watcher does not cause an |
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247 | extra syscall as with epoll, it still adds up to four event changes per |
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248 | incident, so its best to avoid that.</p> |
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249 | </dd> |
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250 | <dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt> |
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251 | <dd> |
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252 | <p>This is not implemented yet (and might never be).</p> |
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253 | </dd> |
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254 | <dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt> |
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255 | <dd> |
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256 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
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257 | it's really slow, but it still scales very well (O(active_fds)).</p> |
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258 | <p>Please note that solaris ports can result in a lot of spurious |
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259 | notifications, so you need to use non-blocking I/O or other means to avoid |
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260 | blocking when no data (or space) is available.</p> |
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261 | </dd> |
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262 | <dt><code>EVBACKEND_ALL</code></dt> |
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263 | <dd> |
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264 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
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265 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
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266 | <code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p> |
190 | </dd> |
267 | </dd> |
191 | </dl> |
268 | </dl> |
192 | </p> |
269 | </p> |
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270 | <p>If one or more of these are ored into the flags value, then only these |
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271 | backends will be tried (in the reverse order as given here). If none are |
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272 | specified, most compiled-in backend will be tried, usually in reverse |
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273 | order of their flag values :)</p> |
193 | </dd> |
274 | </dd> |
194 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
275 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
195 | <dd> |
276 | <dd> |
196 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
277 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
197 | always distinct from the default loop. Unlike the default loop, it cannot |
278 | always distinct from the default loop. Unlike the default loop, it cannot |
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213 | <dd> |
294 | <dd> |
214 | <p>This function reinitialises the kernel state for backends that have |
295 | <p>This function reinitialises the kernel state for backends that have |
215 | one. Despite the name, you can call it anytime, but it makes most sense |
296 | one. Despite the name, you can call it anytime, but it makes most sense |
216 | after forking, in either the parent or child process (or both, but that |
297 | after forking, in either the parent or child process (or both, but that |
217 | again makes little sense).</p> |
298 | again makes little sense).</p> |
218 | <p>You <i>must</i> call this function after forking if and only if you want to |
299 | <p>You <i>must</i> call this function in the child process after forking if and |
219 | use the event library in both processes. If you just fork+exec, you don't |
300 | only if you want to use the event library in both processes. If you just |
220 | have to call it.</p> |
301 | fork+exec, you don't have to call it.</p> |
221 | <p>The function itself is quite fast and it's usually not a problem to call |
302 | <p>The function itself is quite fast and it's usually not a problem to call |
222 | it just in case after a fork. To make this easy, the function will fit in |
303 | it just in case after a fork. To make this easy, the function will fit in |
223 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
304 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
224 | <pre> pthread_atfork (0, 0, ev_default_fork); |
305 | <pre> pthread_atfork (0, 0, ev_default_fork); |
225 | |
306 | |
226 | </pre> |
307 | </pre> |
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308 | <p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use |
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309 | without calling this function, so if you force one of those backends you |
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310 | do not need to care.</p> |
227 | </dd> |
311 | </dd> |
228 | <dt>ev_loop_fork (loop)</dt> |
312 | <dt>ev_loop_fork (loop)</dt> |
229 | <dd> |
313 | <dd> |
230 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
314 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
231 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
315 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
232 | after fork, and how you do this is entirely your own problem.</p> |
316 | after fork, and how you do this is entirely your own problem.</p> |
233 | </dd> |
317 | </dd> |
234 | <dt>unsigned int ev_method (loop)</dt> |
318 | <dt>unsigned int ev_backend (loop)</dt> |
235 | <dd> |
319 | <dd> |
236 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
320 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
237 | use.</p> |
321 | use.</p> |
238 | </dd> |
322 | </dd> |
239 | <dt>ev_tstamp ev_now (loop)</dt> |
323 | <dt>ev_tstamp ev_now (loop)</dt> |
240 | <dd> |
324 | <dd> |
241 | <p>Returns the current "event loop time", which is the time the event loop |
325 | <p>Returns the current "event loop time", which is the time the event loop |
… | |
… | |
259 | your process until at least one new event arrives, and will return after |
343 | your process until at least one new event arrives, and will return after |
260 | one iteration of the loop.</p> |
344 | one iteration of the loop.</p> |
261 | <p>This flags value could be used to implement alternative looping |
345 | <p>This flags value could be used to implement alternative looping |
262 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
346 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
263 | more generic mechanism.</p> |
347 | more generic mechanism.</p> |
|
|
348 | <p>Here are the gory details of what ev_loop does:</p> |
|
|
349 | <pre> 1. If there are no active watchers (reference count is zero), return. |
|
|
350 | 2. Queue and immediately call all prepare watchers. |
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|
351 | 3. If we have been forked, recreate the kernel state. |
|
|
352 | 4. Update the kernel state with all outstanding changes. |
|
|
353 | 5. Update the "event loop time". |
|
|
354 | 6. Calculate for how long to block. |
|
|
355 | 7. Block the process, waiting for events. |
|
|
356 | 8. Update the "event loop time" and do time jump handling. |
|
|
357 | 9. Queue all outstanding timers. |
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|
358 | 10. Queue all outstanding periodics. |
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|
359 | 11. If no events are pending now, queue all idle watchers. |
|
|
360 | 12. Queue all check watchers. |
|
|
361 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
362 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
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|
363 | was used, return, otherwise continue with step #1. |
|
|
364 | |
|
|
365 | </pre> |
264 | </dd> |
366 | </dd> |
265 | <dt>ev_unloop (loop, how)</dt> |
367 | <dt>ev_unloop (loop, how)</dt> |
266 | <dd> |
368 | <dd> |
267 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
369 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
268 | has processed all outstanding events). The <code>how</code> argument must be either |
370 | has processed all outstanding events). The <code>how</code> argument must be either |
269 | <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> call return, or |
371 | <code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or |
270 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
372 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
271 | </dd> |
373 | </dd> |
272 | <dt>ev_ref (loop)</dt> |
374 | <dt>ev_ref (loop)</dt> |
273 | <dt>ev_unref (loop)</dt> |
375 | <dt>ev_unref (loop)</dt> |
274 | <dd> |
376 | <dd> |
… | |
… | |
288 | </div> |
390 | </div> |
289 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
391 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
290 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
392 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
291 | <p>A watcher is a structure that you create and register to record your |
393 | <p>A watcher is a structure that you create and register to record your |
292 | interest in some event. For instance, if you want to wait for STDIN to |
394 | interest in some event. For instance, if you want to wait for STDIN to |
293 | become readable, you would create an ev_io watcher for that:</p> |
395 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
294 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
396 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
295 | { |
397 | { |
296 | ev_io_stop (w); |
398 | ev_io_stop (w); |
297 | ev_unloop (loop, EVUNLOOP_ALL); |
399 | ev_unloop (loop, EVUNLOOP_ALL); |
298 | } |
400 | } |
… | |
… | |
321 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
423 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
322 | *)</code>), and you can stop watching for events at any time by calling the |
424 | *)</code>), and you can stop watching for events at any time by calling the |
323 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
425 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
324 | <p>As long as your watcher is active (has been started but not stopped) you |
426 | <p>As long as your watcher is active (has been started but not stopped) you |
325 | must not touch the values stored in it. Most specifically you must never |
427 | must not touch the values stored in it. Most specifically you must never |
326 | reinitialise it or call its set method.</p> |
428 | reinitialise it or call its set macro.</p> |
327 | <p>You cna check whether an event is active by calling the <code>ev_is_active |
429 | <p>You can check whether an event is active by calling the <code>ev_is_active |
328 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
430 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
329 | callback for it has not been called yet) you cna use the <code>ev_is_pending |
431 | callback for it has not been called yet) you can use the <code>ev_is_pending |
330 | (watcher *)</code> macro.</p> |
432 | (watcher *)</code> macro.</p> |
331 | <p>Each and every callback receives the event loop pointer as first, the |
433 | <p>Each and every callback receives the event loop pointer as first, the |
332 | registered watcher structure as second, and a bitset of received events as |
434 | registered watcher structure as second, and a bitset of received events as |
333 | third argument.</p> |
435 | third argument.</p> |
334 | <p>The rceeived events usually include a single bit per event type received |
436 | <p>The received events usually include a single bit per event type received |
335 | (you can receive multiple events at the same time). The possible bit masks |
437 | (you can receive multiple events at the same time). The possible bit masks |
336 | are:</p> |
438 | are:</p> |
337 | <dl> |
439 | <dl> |
338 | <dt>EV_READ</dt> |
440 | <dt><code>EV_READ</code></dt> |
339 | <dt>EV_WRITE</dt> |
441 | <dt><code>EV_WRITE</code></dt> |
340 | <dd> |
442 | <dd> |
341 | <p>The file descriptor in the ev_io watcher has become readable and/or |
443 | <p>The file descriptor in the <code>ev_io</code> watcher has become readable and/or |
342 | writable.</p> |
444 | writable.</p> |
343 | </dd> |
445 | </dd> |
344 | <dt>EV_TIMEOUT</dt> |
446 | <dt><code>EV_TIMEOUT</code></dt> |
345 | <dd> |
|
|
346 | <p>The ev_timer watcher has timed out.</p> |
|
|
347 | </dd> |
447 | <dd> |
348 | <dt>EV_PERIODIC</dt> |
448 | <p>The <code>ev_timer</code> watcher has timed out.</p> |
349 | <dd> |
449 | </dd> |
350 | <p>The ev_periodic watcher has timed out.</p> |
450 | <dt><code>EV_PERIODIC</code></dt> |
351 | </dd> |
451 | <dd> |
352 | <dt>EV_SIGNAL</dt> |
452 | <p>The <code>ev_periodic</code> watcher has timed out.</p> |
353 | <dd> |
453 | </dd> |
|
|
454 | <dt><code>EV_SIGNAL</code></dt> |
|
|
455 | <dd> |
354 | <p>The signal specified in the ev_signal watcher has been received by a thread.</p> |
456 | <p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p> |
355 | </dd> |
|
|
356 | <dt>EV_CHILD</dt> |
|
|
357 | <dd> |
457 | </dd> |
|
|
458 | <dt><code>EV_CHILD</code></dt> |
|
|
459 | <dd> |
358 | <p>The pid specified in the ev_child watcher has received a status change.</p> |
460 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
359 | </dd> |
|
|
360 | <dt>EV_IDLE</dt> |
|
|
361 | <dd> |
461 | </dd> |
|
|
462 | <dt><code>EV_IDLE</code></dt> |
|
|
463 | <dd> |
362 | <p>The ev_idle watcher has determined that you have nothing better to do.</p> |
464 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
363 | </dd> |
|
|
364 | <dt>EV_PREPARE</dt> |
|
|
365 | <dt>EV_CHECK</dt> |
|
|
366 | <dd> |
465 | </dd> |
|
|
466 | <dt><code>EV_PREPARE</code></dt> |
|
|
467 | <dt><code>EV_CHECK</code></dt> |
|
|
468 | <dd> |
367 | <p>All ev_prepare watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
469 | <p>All <code>ev_prepare</code> watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
368 | to gather new events, and all ev_check watchers are invoked just after |
470 | to gather new events, and all <code>ev_check</code> watchers are invoked just after |
369 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
471 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
370 | received events. Callbacks of both watcher types can start and stop as |
472 | received events. Callbacks of both watcher types can start and stop as |
371 | many watchers as they want, and all of them will be taken into account |
473 | many watchers as they want, and all of them will be taken into account |
372 | (for example, a ev_prepare watcher might start an idle watcher to keep |
474 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
373 | <code>ev_loop</code> from blocking).</p> |
475 | <code>ev_loop</code> from blocking).</p> |
374 | </dd> |
476 | </dd> |
375 | <dt>EV_ERROR</dt> |
477 | <dt><code>EV_ERROR</code></dt> |
376 | <dd> |
478 | <dd> |
377 | <p>An unspecified error has occured, the watcher has been stopped. This might |
479 | <p>An unspecified error has occured, the watcher has been stopped. This might |
378 | happen because the watcher could not be properly started because libev |
480 | happen because the watcher could not be properly started because libev |
379 | ran out of memory, a file descriptor was found to be closed or any other |
481 | ran out of memory, a file descriptor was found to be closed or any other |
380 | problem. You best act on it by reporting the problem and somehow coping |
482 | problem. You best act on it by reporting the problem and somehow coping |
… | |
… | |
389 | |
491 | |
390 | </div> |
492 | </div> |
391 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
493 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
392 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
494 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
393 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
495 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
394 | and read at any time, libev will completely ignore it. This cna be used |
496 | and read at any time, libev will completely ignore it. This can be used |
395 | to associate arbitrary data with your watcher. If you need more data and |
497 | to associate arbitrary data with your watcher. If you need more data and |
396 | don't want to allocate memory and store a pointer to it in that data |
498 | don't want to allocate memory and store a pointer to it in that data |
397 | member, you can also "subclass" the watcher type and provide your own |
499 | member, you can also "subclass" the watcher type and provide your own |
398 | data:</p> |
500 | data:</p> |
399 | <pre> struct my_io |
501 | <pre> struct my_io |
… | |
… | |
426 | <div id="WATCHER_TYPES_CONTENT"> |
528 | <div id="WATCHER_TYPES_CONTENT"> |
427 | <p>This section describes each watcher in detail, but will not repeat |
529 | <p>This section describes each watcher in detail, but will not repeat |
428 | information given in the last section.</p> |
530 | information given in the last section.</p> |
429 | |
531 | |
430 | </div> |
532 | </div> |
431 | <h2 id="struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</h2> |
533 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
432 | <div id="struct_ev_io_is_my_file_descriptor_r-2"> |
534 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
433 | <p>I/O watchers check whether a file descriptor is readable or writable |
535 | <p>I/O watchers check whether a file descriptor is readable or writable |
434 | in each iteration of the event loop (This behaviour is called |
536 | in each iteration of the event loop (This behaviour is called |
435 | level-triggering because you keep receiving events as long as the |
537 | level-triggering because you keep receiving events as long as the |
436 | condition persists. Remember you cna stop the watcher if you don't want to |
538 | condition persists. Remember you can stop the watcher if you don't want to |
437 | act on the event and neither want to receive future events).</p> |
539 | act on the event and neither want to receive future events).</p> |
438 | <p>In general you can register as many read and/or write event watchers oer |
540 | <p>In general you can register as many read and/or write event watchers per |
439 | fd as you want (as long as you don't confuse yourself). Setting all file |
541 | fd as you want (as long as you don't confuse yourself). Setting all file |
440 | descriptors to non-blocking mode is also usually a good idea (but not |
542 | descriptors to non-blocking mode is also usually a good idea (but not |
441 | required if you know what you are doing).</p> |
543 | required if you know what you are doing).</p> |
442 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
544 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
443 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
545 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
444 | descriptors correctly if you register interest in two or more fds pointing |
546 | descriptors correctly if you register interest in two or more fds pointing |
445 | to the same file/socket etc. description.</p> |
547 | to the same underlying file/socket etc. description (that is, they share |
|
|
548 | the same underlying "file open").</p> |
446 | <p>If you must do this, then force the use of a known-to-be-good backend |
549 | <p>If you must do this, then force the use of a known-to-be-good backend |
447 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
550 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
448 | EVMETHOD_POLL).</p> |
551 | <code>EVBACKEND_POLL</code>).</p> |
449 | <dl> |
552 | <dl> |
450 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
553 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
451 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
554 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
452 | <dd> |
555 | <dd> |
453 | <p>Configures an ev_io watcher. The fd is the file descriptor to rceeive |
556 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
454 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
557 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
455 | EV_WRITE</code> to receive the given events.</p> |
558 | EV_WRITE</code> to receive the given events.</p> |
|
|
559 | <p>Please note that most of the more scalable backend mechanisms (for example |
|
|
560 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
561 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
562 | treat callback invocation as hint only), or retest separately with a safe |
|
|
563 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
564 | <code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this |
|
|
565 | problem. Also note that it is quite easy to have your callback invoked |
|
|
566 | when the readyness condition is no longer valid even when employing |
|
|
567 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
568 | I/O unconditionally.</p> |
456 | </dd> |
569 | </dd> |
457 | </dl> |
570 | </dl> |
458 | |
571 | |
459 | </div> |
572 | </div> |
460 | <h2 id="struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</h2> |
573 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
461 | <div id="struct_ev_timer_relative_and_optiona-2"> |
574 | <div id="code_ev_timer_code_relative_and_opti-2"> |
462 | <p>Timer watchers are simple relative timers that generate an event after a |
575 | <p>Timer watchers are simple relative timers that generate an event after a |
463 | given time, and optionally repeating in regular intervals after that.</p> |
576 | given time, and optionally repeating in regular intervals after that.</p> |
464 | <p>The timers are based on real time, that is, if you register an event that |
577 | <p>The timers are based on real time, that is, if you register an event that |
465 | times out after an hour and youreset your system clock to last years |
578 | times out after an hour and you reset your system clock to last years |
466 | time, it will still time out after (roughly) and hour. "Roughly" because |
579 | time, it will still time out after (roughly) and hour. "Roughly" because |
467 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
580 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
468 | monotonic clock option helps a lot here).</p> |
581 | monotonic clock option helps a lot here).</p> |
469 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
582 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
470 | time. This is usually the right thing as this timestamp refers to the time |
583 | time. This is usually the right thing as this timestamp refers to the time |
471 | of the event triggering whatever timeout you are modifying/starting. If |
584 | of the event triggering whatever timeout you are modifying/starting. If |
472 | you suspect event processing to be delayed and you *need* to base the timeout |
585 | you suspect event processing to be delayed and you <i>need</i> to base the timeout |
473 | ion the current time, use something like this to adjust for this:</p> |
586 | on the current time, use something like this to adjust for this:</p> |
474 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
587 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
475 | |
588 | |
476 | </pre> |
589 | </pre> |
|
|
590 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
591 | but if multiple timers become ready during the same loop iteration then |
|
|
592 | order of execution is undefined.</p> |
477 | <dl> |
593 | <dl> |
478 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
594 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
479 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
595 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
480 | <dd> |
596 | <dd> |
481 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
597 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
483 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
599 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
484 | later, again, and again, until stopped manually.</p> |
600 | later, again, and again, until stopped manually.</p> |
485 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
601 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
486 | configure a timer to trigger every 10 seconds, then it will trigger at |
602 | configure a timer to trigger every 10 seconds, then it will trigger at |
487 | exactly 10 second intervals. If, however, your program cannot keep up with |
603 | exactly 10 second intervals. If, however, your program cannot keep up with |
488 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
604 | the timer (because it takes longer than those 10 seconds to do stuff) the |
489 | timer will not fire more than once per event loop iteration.</p> |
605 | timer will not fire more than once per event loop iteration.</p> |
490 | </dd> |
606 | </dd> |
491 | <dt>ev_timer_again (loop)</dt> |
607 | <dt>ev_timer_again (loop)</dt> |
492 | <dd> |
608 | <dd> |
493 | <p>This will act as if the timer timed out and restart it again if it is |
609 | <p>This will act as if the timer timed out and restart it again if it is |
… | |
… | |
497 | value), or reset the running timer to the repeat value.</p> |
613 | value), or reset the running timer to the repeat value.</p> |
498 | <p>This sounds a bit complicated, but here is a useful and typical |
614 | <p>This sounds a bit complicated, but here is a useful and typical |
499 | example: Imagine you have a tcp connection and you want a so-called idle |
615 | example: Imagine you have a tcp connection and you want a so-called idle |
500 | timeout, that is, you want to be called when there have been, say, 60 |
616 | timeout, that is, you want to be called when there have been, say, 60 |
501 | seconds of inactivity on the socket. The easiest way to do this is to |
617 | seconds of inactivity on the socket. The easiest way to do this is to |
502 | configure an ev_timer with after=repeat=60 and calling ev_timer_again each |
618 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
503 | time you successfully read or write some data. If you go into an idle |
619 | time you successfully read or write some data. If you go into an idle |
504 | state where you do not expect data to travel on the socket, you can stop |
620 | state where you do not expect data to travel on the socket, you can stop |
505 | the timer, and again will automatically restart it if need be.</p> |
621 | the timer, and again will automatically restart it if need be.</p> |
506 | </dd> |
622 | </dd> |
507 | </dl> |
623 | </dl> |
508 | |
624 | |
509 | </div> |
625 | </div> |
510 | <h2 id="ev_periodic_to_cron_or_not_to_cron_i">ev_periodic - to cron or not to cron it</h2> |
626 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
511 | <div id="ev_periodic_to_cron_or_not_to_cron_i-2"> |
627 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
512 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
628 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
513 | (and unfortunately a bit complex).</p> |
629 | (and unfortunately a bit complex).</p> |
514 | <p>Unlike ev_timer's, they are not based on real time (or relative time) |
630 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
515 | but on wallclock time (absolute time). You can tell a periodic watcher |
631 | but on wallclock time (absolute time). You can tell a periodic watcher |
516 | to trigger "at" some specific point in time. For example, if you tell a |
632 | to trigger "at" some specific point in time. For example, if you tell a |
517 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
633 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
518 | + 10.>) and then reset your system clock to the last year, then it will |
634 | + 10.>) and then reset your system clock to the last year, then it will |
519 | take a year to trigger the event (unlike an ev_timer, which would trigger |
635 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
520 | roughly 10 seconds later and of course not if you reset your system time |
636 | roughly 10 seconds later and of course not if you reset your system time |
521 | again).</p> |
637 | again).</p> |
522 | <p>They can also be used to implement vastly more complex timers, such as |
638 | <p>They can also be used to implement vastly more complex timers, such as |
523 | triggering an event on eahc midnight, local time.</p> |
639 | triggering an event on eahc midnight, local time.</p> |
|
|
640 | <p>As with timers, the callback is guarenteed to be invoked only when the |
|
|
641 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
|
|
642 | during the same loop iteration then order of execution is undefined.</p> |
524 | <dl> |
643 | <dl> |
525 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
644 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
526 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
645 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
527 | <dd> |
646 | <dd> |
528 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
647 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
529 | operation, and we will explain them from simplest to complex:</p> |
648 | operation, and we will explain them from simplest to complex:</p> |
530 | |
|
|
531 | |
|
|
532 | |
|
|
533 | |
|
|
534 | <p> |
649 | <p> |
535 | <dl> |
650 | <dl> |
536 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
651 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
537 | <dd> |
652 | <dd> |
538 | <p>In this configuration the watcher triggers an event at the wallclock time |
653 | <p>In this configuration the watcher triggers an event at the wallclock time |
… | |
… | |
550 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
665 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
551 | |
666 | |
552 | </pre> |
667 | </pre> |
553 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
668 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
554 | but only that the the callback will be called when the system time shows a |
669 | but only that the the callback will be called when the system time shows a |
555 | full hour (UTC), or more correct, when the system time is evenly divisible |
670 | full hour (UTC), or more correctly, when the system time is evenly divisible |
556 | by 3600.</p> |
671 | by 3600.</p> |
557 | <p>Another way to think about it (for the mathematically inclined) is that |
672 | <p>Another way to think about it (for the mathematically inclined) is that |
558 | ev_periodic will try to run the callback in this mode at the next possible |
673 | <code>ev_periodic</code> will try to run the callback in this mode at the next possible |
559 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
674 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
560 | </dd> |
675 | </dd> |
561 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
676 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
562 | <dd> |
677 | <dd> |
563 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
678 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
564 | ignored. Instead, each time the periodic watcher gets scheduled, the |
679 | ignored. Instead, each time the periodic watcher gets scheduled, the |
565 | reschedule callback will be called with the watcher as first, and the |
680 | reschedule callback will be called with the watcher as first, and the |
566 | current time as second argument.</p> |
681 | current time as second argument.</p> |
567 | <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other |
682 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
568 | periodic watcher, ever, or make any event loop modificstions</i>. If you need |
683 | ever, or make any event loop modifications</i>. If you need to stop it, |
569 | to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards.</p> |
684 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
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|
685 | starting a prepare watcher).</p> |
570 | <p>Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
686 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
571 | ev_tstamp now)>, e.g.:</p> |
687 | ev_tstamp now)</code>, e.g.:</p> |
572 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
688 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
573 | { |
689 | { |
574 | return now + 60.; |
690 | return now + 60.; |
575 | } |
691 | } |
576 | |
692 | |
577 | </pre> |
693 | </pre> |
578 | <p>It must return the next time to trigger, based on the passed time value |
694 | <p>It must return the next time to trigger, based on the passed time value |
579 | (that is, the lowest time value larger than to the second argument). It |
695 | (that is, the lowest time value larger than to the second argument). It |
580 | will usually be called just before the callback will be triggered, but |
696 | will usually be called just before the callback will be triggered, but |
581 | might be called at other times, too.</p> |
697 | might be called at other times, too.</p> |
|
|
698 | <p>NOTE: <i>This callback must always return a time that is later than the |
|
|
699 | passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p> |
582 | <p>This can be used to create very complex timers, such as a timer that |
700 | <p>This can be used to create very complex timers, such as a timer that |
583 | triggers on each midnight, local time. To do this, you would calculate the |
701 | triggers on each midnight, local time. To do this, you would calculate the |
584 | next midnight after <code>now</code> and return the timestamp value for this. How you do this |
702 | next midnight after <code>now</code> and return the timestamp value for this. How |
585 | is, again, up to you (but it is not trivial).</p> |
703 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
704 | reason I omitted it as an example).</p> |
586 | </dd> |
705 | </dd> |
587 | </dl> |
706 | </dl> |
588 | </p> |
707 | </p> |
589 | </dd> |
708 | </dd> |
590 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
709 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
… | |
… | |
595 | program when the crontabs have changed).</p> |
714 | program when the crontabs have changed).</p> |
596 | </dd> |
715 | </dd> |
597 | </dl> |
716 | </dl> |
598 | |
717 | |
599 | </div> |
718 | </div> |
600 | <h2 id="ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</h2> |
719 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
601 | <div id="ev_signal_signal_me_when_a_signal_ge-2"> |
720 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
602 | <p>Signal watchers will trigger an event when the process receives a specific |
721 | <p>Signal watchers will trigger an event when the process receives a specific |
603 | signal one or more times. Even though signals are very asynchronous, libev |
722 | signal one or more times. Even though signals are very asynchronous, libev |
604 | will try it's best to deliver signals synchronously, i.e. as part of the |
723 | will try it's best to deliver signals synchronously, i.e. as part of the |
605 | normal event processing, like any other event.</p> |
724 | normal event processing, like any other event.</p> |
606 | <p>You cna configure as many watchers as you like per signal. Only when the |
725 | <p>You can configure as many watchers as you like per signal. Only when the |
607 | first watcher gets started will libev actually register a signal watcher |
726 | first watcher gets started will libev actually register a signal watcher |
608 | with the kernel (thus it coexists with your own signal handlers as long |
727 | with the kernel (thus it coexists with your own signal handlers as long |
609 | as you don't register any with libev). Similarly, when the last signal |
728 | as you don't register any with libev). Similarly, when the last signal |
610 | watcher for a signal is stopped libev will reset the signal handler to |
729 | watcher for a signal is stopped libev will reset the signal handler to |
611 | SIG_DFL (regardless of what it was set to before).</p> |
730 | SIG_DFL (regardless of what it was set to before).</p> |
… | |
… | |
617 | of the <code>SIGxxx</code> constants).</p> |
736 | of the <code>SIGxxx</code> constants).</p> |
618 | </dd> |
737 | </dd> |
619 | </dl> |
738 | </dl> |
620 | |
739 | |
621 | </div> |
740 | </div> |
622 | <h2 id="ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</h2> |
741 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
623 | <div id="ev_child_wait_for_pid_status_changes-2"> |
742 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
624 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
743 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
625 | some child status changes (most typically when a child of yours dies).</p> |
744 | some child status changes (most typically when a child of yours dies).</p> |
626 | <dl> |
745 | <dl> |
627 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
746 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
628 | <dt>ev_child_set (ev_child *, int pid)</dt> |
747 | <dt>ev_child_set (ev_child *, int pid)</dt> |
629 | <dd> |
748 | <dd> |
630 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
749 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
631 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
750 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
632 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
751 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
633 | the status word (use the macros from <code>sys/wait.h</code>). The <code>rpid</code> member |
752 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
|
|
753 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
634 | contains the pid of the process causing the status change.</p> |
754 | process causing the status change.</p> |
635 | </dd> |
755 | </dd> |
636 | </dl> |
756 | </dl> |
637 | |
757 | |
638 | </div> |
758 | </div> |
639 | <h2 id="ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</h2> |
759 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
640 | <div id="ev_idle_when_you_ve_got_nothing_bett-2"> |
760 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
641 | <p>Idle watchers trigger events when there are no other I/O or timer (or |
761 | <p>Idle watchers trigger events when there are no other events are pending |
642 | periodic) events pending. That is, as long as your process is busy |
762 | (prepare, check and other idle watchers do not count). That is, as long |
643 | handling sockets or timeouts it will not be called. But when your process |
763 | as your process is busy handling sockets or timeouts (or even signals, |
644 | is idle all idle watchers are being called again and again - until |
764 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
765 | watchers are being called again and again, once per event loop iteration - |
645 | stopped, that is, or your process receives more events.</p> |
766 | until stopped, that is, or your process receives more events and becomes |
|
|
767 | busy.</p> |
646 | <p>The most noteworthy effect is that as long as any idle watchers are |
768 | <p>The most noteworthy effect is that as long as any idle watchers are |
647 | active, the process will not block when waiting for new events.</p> |
769 | active, the process will not block when waiting for new events.</p> |
648 | <p>Apart from keeping your process non-blocking (which is a useful |
770 | <p>Apart from keeping your process non-blocking (which is a useful |
649 | effect on its own sometimes), idle watchers are a good place to do |
771 | effect on its own sometimes), idle watchers are a good place to do |
650 | "pseudo-background processing", or delay processing stuff to after the |
772 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
657 | believe me.</p> |
779 | believe me.</p> |
658 | </dd> |
780 | </dd> |
659 | </dl> |
781 | </dl> |
660 | |
782 | |
661 | </div> |
783 | </div> |
662 | <h2 id="prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</h2> |
784 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
663 | <div id="prepare_and_check_your_hooks_into_th-2"> |
785 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
664 | <p>Prepare and check watchers usually (but not always) are used in |
786 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
665 | tandom. Prepare watchers get invoked before the process blocks and check |
787 | prepare watchers get invoked before the process blocks and check watchers |
666 | watchers afterwards.</p> |
788 | afterwards.</p> |
667 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
789 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
668 | could be used, for example, to track variable changes, implement your own |
790 | could be used, for example, to track variable changes, implement your own |
669 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
791 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
670 | <p>This is done by examining in each prepare call which file descriptors need |
792 | <p>This is done by examining in each prepare call which file descriptors need |
671 | to be watched by the other library, registering ev_io watchers for them |
793 | to be watched by the other library, registering <code>ev_io</code> watchers for |
672 | and starting an ev_timer watcher for any timeouts (many libraries provide |
794 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
673 | just this functionality). Then, in the check watcher you check for any |
795 | provide just this functionality). Then, in the check watcher you check for |
674 | events that occured (by making your callbacks set soem flags for example) |
796 | any events that occured (by checking the pending status of all watchers |
675 | and call back into the library.</p> |
797 | and stopping them) and call back into the library. The I/O and timer |
|
|
798 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
799 | because you never know, you know?).</p> |
676 | <p>As another example, the perl Coro module uses these hooks to integrate |
800 | <p>As another example, the Perl Coro module uses these hooks to integrate |
677 | coroutines into libev programs, by yielding to other active coroutines |
801 | coroutines into libev programs, by yielding to other active coroutines |
678 | during each prepare and only letting the process block if no coroutines |
802 | during each prepare and only letting the process block if no coroutines |
679 | are ready to run.</p> |
803 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
804 | with priority higher than or equal to the event loop and one coroutine |
|
|
805 | of lower priority, but only once, using idle watchers to keep the event |
|
|
806 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
807 | low-priority coroutines to idle/background tasks).</p> |
680 | <dl> |
808 | <dl> |
681 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
809 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
682 | <dt>ev_check_init (ev_check *, callback)</dt> |
810 | <dt>ev_check_init (ev_check *, callback)</dt> |
683 | <dd> |
811 | <dd> |
684 | <p>Initialises and configures the prepare or check watcher - they have no |
812 | <p>Initialises and configures the prepare or check watcher - they have no |
685 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
813 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
686 | macros, but using them is utterly, utterly pointless.</p> |
814 | macros, but using them is utterly, utterly and completely pointless.</p> |
687 | </dd> |
815 | </dd> |
688 | </dl> |
816 | </dl> |
689 | |
817 | |
690 | </div> |
818 | </div> |
691 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
819 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
692 | <div id="OTHER_FUNCTIONS_CONTENT"> |
820 | <div id="OTHER_FUNCTIONS_CONTENT"> |
693 | <p>There are some other fucntions of possible interest. Described. Here. Now.</p> |
821 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
694 | <dl> |
822 | <dl> |
695 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
823 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
696 | <dd> |
824 | <dd> |
697 | <p>This function combines a simple timer and an I/O watcher, calls your |
825 | <p>This function combines a simple timer and an I/O watcher, calls your |
698 | callback on whichever event happens first and automatically stop both |
826 | callback on whichever event happens first and automatically stop both |
699 | watchers. This is useful if you want to wait for a single event on an fd |
827 | watchers. This is useful if you want to wait for a single event on an fd |
700 | or timeout without havign to allocate/configure/start/stop/free one or |
828 | or timeout without having to allocate/configure/start/stop/free one or |
701 | more watchers yourself.</p> |
829 | more watchers yourself.</p> |
702 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events is |
830 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events |
703 | ignored. Otherwise, an ev_io watcher for the given <code>fd</code> and <code>events</code> set |
831 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
704 | will be craeted and started.</p> |
832 | <code>events</code> set will be craeted and started.</p> |
705 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
833 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
706 | started. Otherwise an ev_timer watcher with after = <code>timeout</code> (and repeat |
834 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
707 | = 0) will be started.</p> |
835 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
|
|
836 | dubious value.</p> |
708 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and |
837 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets |
709 | gets passed an events set (normally a combination of EV_ERROR, EV_READ, |
838 | passed an <code>revents</code> set like normal event callbacks (a combination of |
710 | EV_WRITE or EV_TIMEOUT) and the <code>arg</code> value passed to <code>ev_once</code>:</p> |
839 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
|
|
840 | value passed to <code>ev_once</code>:</p> |
711 | <pre> static void stdin_ready (int revents, void *arg) |
841 | <pre> static void stdin_ready (int revents, void *arg) |
712 | { |
842 | { |
713 | if (revents & EV_TIMEOUT) |
843 | if (revents & EV_TIMEOUT) |
714 | /* doh, nothing entered */ |
844 | /* doh, nothing entered */; |
715 | else if (revents & EV_READ) |
845 | else if (revents & EV_READ) |
716 | /* stdin might have data for us, joy! */ |
846 | /* stdin might have data for us, joy! */; |
717 | } |
847 | } |
718 | |
848 | |
719 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
849 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
720 | |
850 | |
721 | </pre> |
851 | </pre> |
722 | </dd> |
852 | </dd> |
723 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
853 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
724 | <dd> |
854 | <dd> |
725 | <p>Feeds the given event set into the event loop, as if the specified event |
855 | <p>Feeds the given event set into the event loop, as if the specified event |
726 | has happened for the specified watcher (which must be a pointer to an |
856 | had happened for the specified watcher (which must be a pointer to an |
727 | initialised but not necessarily active event watcher).</p> |
857 | initialised but not necessarily started event watcher).</p> |
728 | </dd> |
858 | </dd> |
729 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
859 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
730 | <dd> |
860 | <dd> |
731 | <p>Feed an event on the given fd, as if a file descriptor backend detected it.</p> |
861 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
|
|
862 | the given events it.</p> |
732 | </dd> |
863 | </dd> |
733 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
864 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
734 | <dd> |
865 | <dd> |
735 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
866 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
736 | </dd> |
867 | </dd> |
737 | </dl> |
868 | </dl> |
|
|
869 | |
|
|
870 | </div> |
|
|
871 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
872 | <div id="LIBEVENT_EMULATION_CONTENT"> |
|
|
873 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
874 | emulate the internals of libevent, so here are some usage hints:</p> |
|
|
875 | <dl> |
|
|
876 | <dt>* Use it by including <event.h>, as usual.</dt> |
|
|
877 | <dt>* The following members are fully supported: ev_base, ev_callback, |
|
|
878 | ev_arg, ev_fd, ev_res, ev_events.</dt> |
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879 | <dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is |
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880 | maintained by libev, it does not work exactly the same way as in libevent (consider |
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881 | it a private API).</dt> |
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882 | <dt>* Priorities are not currently supported. Initialising priorities |
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883 | will fail and all watchers will have the same priority, even though there |
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884 | is an ev_pri field.</dt> |
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885 | <dt>* Other members are not supported.</dt> |
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886 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
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887 | to use the libev header file and library.</dt> |
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888 | </dl> |
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889 | |
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890 | </div> |
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891 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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892 | <div id="C_SUPPORT_CONTENT"> |
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893 | <p>TBD.</p> |
738 | |
894 | |
739 | </div> |
895 | </div> |
740 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
896 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
741 | <div id="AUTHOR_CONTENT"> |
897 | <div id="AUTHOR_CONTENT"> |
742 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
898 | <p>Marc Lehmann <libev@schmorp.de>.</p> |