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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 10:06:08 2007" /> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
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26 | <ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | </ul> |
28 | </ul> |
28 | </li> |
29 | </li> |
29 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> |
31 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
32 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
32 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> |
33 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> |
33 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
34 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> |
34 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
35 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> |
35 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
36 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li> |
36 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
37 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li> |
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38 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> |
37 | </ul> |
39 | </ul> |
38 | </li> |
40 | </li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
41 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
42 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
43 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
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44 | <li><a href="#EMBEDDING">EMBEDDING</a> |
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45 | <ul><li><a href="#FILESETS">FILESETS</a> |
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46 | <ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li> |
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47 | <li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> |
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48 | <li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> |
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49 | </ul> |
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50 | </li> |
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51 | <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> |
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52 | <li><a href="#EXAMPLES">EXAMPLES</a></li> |
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53 | </ul> |
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54 | </li> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
55 | <li><a href="#AUTHOR">AUTHOR</a> |
43 | </li> |
56 | </li> |
44 | </ul><hr /> |
57 | </ul><hr /> |
45 | <!-- INDEX END --> |
58 | <!-- INDEX END --> |
46 | |
59 | |
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96 | <div id="TIME_REPRESENTATION_CONTENT"> |
109 | <div id="TIME_REPRESENTATION_CONTENT"> |
97 | <p>Libev represents time as a single floating point number, representing the |
110 | <p>Libev represents time as a single floating point number, representing the |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
111 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | the beginning of 1970, details are complicated, don't ask). This type is |
112 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
113 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
101 | to the double type in C.</p> |
114 | to the <code>double</code> type in C, and when you need to do any calculations on |
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115 | it, you should treat it as such.</p> |
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116 | |
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117 | |
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118 | |
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119 | |
102 | |
120 | |
103 | </div> |
121 | </div> |
104 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
122 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
105 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
123 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
106 | <p>These functions can be called anytime, even before initialising the |
124 | <p>These functions can be called anytime, even before initialising the |
107 | library in any way.</p> |
125 | library in any way.</p> |
108 | <dl> |
126 | <dl> |
109 | <dt>ev_tstamp ev_time ()</dt> |
127 | <dt>ev_tstamp ev_time ()</dt> |
110 | <dd> |
128 | <dd> |
111 | <p>Returns the current time as libev would use it.</p> |
129 | <p>Returns the current time as libev would use it. Please note that the |
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130 | <code>ev_now</code> function is usually faster and also often returns the timestamp |
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131 | you actually want to know.</p> |
112 | </dd> |
132 | </dd> |
113 | <dt>int ev_version_major ()</dt> |
133 | <dt>int ev_version_major ()</dt> |
114 | <dt>int ev_version_minor ()</dt> |
134 | <dt>int ev_version_minor ()</dt> |
115 | <dd> |
135 | <dd> |
116 | <p>You can find out the major and minor version numbers of the library |
136 | <p>You can find out the major and minor version numbers of the library |
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120 | version of the library your program was compiled against.</p> |
140 | version of the library your program was compiled against.</p> |
121 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
141 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
122 | as this indicates an incompatible change. Minor versions are usually |
142 | as this indicates an incompatible change. Minor versions are usually |
123 | compatible to older versions, so a larger minor version alone is usually |
143 | compatible to older versions, so a larger minor version alone is usually |
124 | not a problem.</p> |
144 | not a problem.</p> |
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145 | <p>Example: make sure we haven't accidentally been linked against the wrong |
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146 | version:</p> |
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147 | <pre> assert (("libev version mismatch", |
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148 | ev_version_major () == EV_VERSION_MAJOR |
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149 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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150 | |
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151 | </pre> |
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152 | </dd> |
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153 | <dt>unsigned int ev_supported_backends ()</dt> |
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154 | <dd> |
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155 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
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156 | value) compiled into this binary of libev (independent of their |
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157 | availability on the system you are running on). See <code>ev_default_loop</code> for |
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158 | a description of the set values.</p> |
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159 | <p>Example: make sure we have the epoll method, because yeah this is cool and |
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160 | a must have and can we have a torrent of it please!!!11</p> |
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161 | <pre> assert (("sorry, no epoll, no sex", |
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162 | ev_supported_backends () & EVBACKEND_EPOLL)); |
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163 | |
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164 | </pre> |
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165 | </dd> |
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166 | <dt>unsigned int ev_recommended_backends ()</dt> |
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167 | <dd> |
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168 | <p>Return the set of all backends compiled into this binary of libev and also |
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169 | recommended for this platform. This set is often smaller than the one |
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170 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
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171 | most BSDs and will not be autodetected unless you explicitly request it |
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172 | (assuming you know what you are doing). This is the set of backends that |
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173 | libev will probe for if you specify no backends explicitly.</p> |
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174 | </dd> |
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175 | <dt>unsigned int ev_embeddable_backends ()</dt> |
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176 | <dd> |
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177 | <p>Returns the set of backends that are embeddable in other event loops. This |
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178 | is the theoretical, all-platform, value. To find which backends |
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179 | might be supported on the current system, you would need to look at |
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180 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
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181 | recommended ones.</p> |
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182 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
125 | </dd> |
183 | </dd> |
126 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
184 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
127 | <dd> |
185 | <dd> |
128 | <p>Sets the allocation function to use (the prototype is similar to the |
186 | <p>Sets the allocation function to use (the prototype is similar to the |
129 | realloc C function, the semantics are identical). It is used to allocate |
187 | realloc C function, the semantics are identical). It is used to allocate |
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131 | needs to be allocated, the library might abort or take some potentially |
189 | needs to be allocated, the library might abort or take some potentially |
132 | destructive action. The default is your system realloc function.</p> |
190 | destructive action. The default is your system realloc function.</p> |
133 | <p>You could override this function in high-availability programs to, say, |
191 | <p>You could override this function in high-availability programs to, say, |
134 | free some memory if it cannot allocate memory, to use a special allocator, |
192 | free some memory if it cannot allocate memory, to use a special allocator, |
135 | or even to sleep a while and retry until some memory is available.</p> |
193 | or even to sleep a while and retry until some memory is available.</p> |
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194 | <p>Example: replace the libev allocator with one that waits a bit and then |
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195 | retries: better than mine).</p> |
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196 | <pre> static void * |
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197 | persistent_realloc (void *ptr, long size) |
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198 | { |
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199 | for (;;) |
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200 | { |
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201 | void *newptr = realloc (ptr, size); |
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202 | |
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203 | if (newptr) |
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204 | return newptr; |
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205 | |
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206 | sleep (60); |
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207 | } |
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208 | } |
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209 | |
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210 | ... |
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211 | ev_set_allocator (persistent_realloc); |
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212 | |
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213 | </pre> |
136 | </dd> |
214 | </dd> |
137 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
215 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
138 | <dd> |
216 | <dd> |
139 | <p>Set the callback function to call on a retryable syscall error (such |
217 | <p>Set the callback function to call on a retryable syscall error (such |
140 | as failed select, poll, epoll_wait). The message is a printable string |
218 | as failed select, poll, epoll_wait). The message is a printable string |
141 | indicating the system call or subsystem causing the problem. If this |
219 | indicating the system call or subsystem causing the problem. If this |
142 | callback is set, then libev will expect it to remedy the sitution, no |
220 | callback is set, then libev will expect it to remedy the sitution, no |
143 | matter what, when it returns. That is, libev will generally retry the |
221 | matter what, when it returns. That is, libev will generally retry the |
144 | requested operation, or, if the condition doesn't go away, do bad stuff |
222 | requested operation, or, if the condition doesn't go away, do bad stuff |
145 | (such as abort).</p> |
223 | (such as abort).</p> |
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224 | <p>Example: do the same thing as libev does internally:</p> |
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225 | <pre> static void |
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226 | fatal_error (const char *msg) |
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227 | { |
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228 | perror (msg); |
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229 | abort (); |
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230 | } |
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231 | |
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232 | ... |
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233 | ev_set_syserr_cb (fatal_error); |
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234 | |
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235 | </pre> |
146 | </dd> |
236 | </dd> |
147 | </dl> |
237 | </dl> |
148 | |
238 | |
149 | </div> |
239 | </div> |
150 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
240 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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162 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
252 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
163 | <dd> |
253 | <dd> |
164 | <p>This will initialise the default event loop if it hasn't been initialised |
254 | <p>This will initialise the default event loop if it hasn't been initialised |
165 | yet and return it. If the default loop could not be initialised, returns |
255 | yet and return it. If the default loop could not be initialised, returns |
166 | false. If it already was initialised it simply returns it (and ignores the |
256 | false. If it already was initialised it simply returns it (and ignores the |
167 | flags).</p> |
257 | flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p> |
168 | <p>If you don't know what event loop to use, use the one returned from this |
258 | <p>If you don't know what event loop to use, use the one returned from this |
169 | function.</p> |
259 | function.</p> |
170 | <p>The flags argument can be used to specify special behaviour or specific |
260 | <p>The flags argument can be used to specify special behaviour or specific |
171 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p> |
261 | backends to use, and is usually specified as <code>0</code> (or <code>EVFLAG_AUTO</code>).</p> |
172 | <p>It supports the following flags:</p> |
262 | <p>The following flags are supported:</p> |
173 | <p> |
263 | <p> |
174 | <dl> |
264 | <dl> |
175 | <dt><code>EVFLAG_AUTO</code></dt> |
265 | <dt><code>EVFLAG_AUTO</code></dt> |
176 | <dd> |
266 | <dd> |
177 | <p>The default flags value. Use this if you have no clue (it's the right |
267 | <p>The default flags value. Use this if you have no clue (it's the right |
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184 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
274 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
185 | override the flags completely if it is found in the environment. This is |
275 | override the flags completely if it is found in the environment. This is |
186 | useful to try out specific backends to test their performance, or to work |
276 | useful to try out specific backends to test their performance, or to work |
187 | around bugs.</p> |
277 | around bugs.</p> |
188 | </dd> |
278 | </dd> |
189 | <dt><code>EVMETHOD_SELECT</code> (portable select backend)</dt> |
279 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
190 | <dt><code>EVMETHOD_POLL</code> (poll backend, available everywhere except on windows)</dt> |
280 | <dd> |
191 | <dt><code>EVMETHOD_EPOLL</code> (linux only)</dt> |
281 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
192 | <dt><code>EVMETHOD_KQUEUE</code> (some bsds only)</dt> |
282 | libev tries to roll its own fd_set with no limits on the number of fds, |
193 | <dt><code>EVMETHOD_DEVPOLL</code> (solaris 8 only)</dt> |
283 | but if that fails, expect a fairly low limit on the number of fds when |
194 | <dt><code>EVMETHOD_PORT</code> (solaris 10 only)</dt> |
284 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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285 | the fastest backend for a low number of fds.</p> |
195 | <dd> |
286 | </dd> |
196 | <p>If one or more of these are ored into the flags value, then only these |
287 | <dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
197 | backends will be tried (in the reverse order as given here). If one are |
288 | <dd> |
198 | specified, any backend will do.</p> |
289 | <p>And this is your standard poll(2) backend. It's more complicated than |
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290 | select, but handles sparse fds better and has no artificial limit on the |
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291 | number of fds you can use (except it will slow down considerably with a |
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292 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
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293 | </dd> |
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294 | <dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt> |
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295 | <dd> |
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296 | <p>For few fds, this backend is a bit little slower than poll and select, |
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297 | but it scales phenomenally better. While poll and select usually scale like |
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298 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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299 | either O(1) or O(active_fds).</p> |
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300 | <p>While stopping and starting an I/O watcher in the same iteration will |
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301 | result in some caching, there is still a syscall per such incident |
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302 | (because the fd could point to a different file description now), so its |
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303 | best to avoid that. Also, dup()ed file descriptors might not work very |
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304 | well if you register events for both fds.</p> |
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305 | <p>Please note that epoll sometimes generates spurious notifications, so you |
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306 | need to use non-blocking I/O or other means to avoid blocking when no data |
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307 | (or space) is available.</p> |
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308 | </dd> |
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309 | <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> |
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310 | <dd> |
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311 | <p>Kqueue deserves special mention, as at the time of this writing, it |
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312 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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313 | anything but sockets and pipes, except on Darwin, where of course its |
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314 | completely useless). For this reason its not being "autodetected" |
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315 | unless you explicitly specify it explicitly in the flags (i.e. using |
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316 | <code>EVBACKEND_KQUEUE</code>).</p> |
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317 | <p>It scales in the same way as the epoll backend, but the interface to the |
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318 | kernel is more efficient (which says nothing about its actual speed, of |
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319 | course). While starting and stopping an I/O watcher does not cause an |
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320 | extra syscall as with epoll, it still adds up to four event changes per |
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321 | incident, so its best to avoid that.</p> |
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322 | </dd> |
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323 | <dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt> |
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324 | <dd> |
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325 | <p>This is not implemented yet (and might never be).</p> |
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326 | </dd> |
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327 | <dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt> |
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328 | <dd> |
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329 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
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330 | it's really slow, but it still scales very well (O(active_fds)).</p> |
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331 | <p>Please note that solaris ports can result in a lot of spurious |
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332 | notifications, so you need to use non-blocking I/O or other means to avoid |
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333 | blocking when no data (or space) is available.</p> |
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334 | </dd> |
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335 | <dt><code>EVBACKEND_ALL</code></dt> |
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336 | <dd> |
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337 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
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338 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
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339 | <code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p> |
199 | </dd> |
340 | </dd> |
200 | </dl> |
341 | </dl> |
201 | </p> |
342 | </p> |
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343 | <p>If one or more of these are ored into the flags value, then only these |
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344 | backends will be tried (in the reverse order as given here). If none are |
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345 | specified, most compiled-in backend will be tried, usually in reverse |
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346 | order of their flag values :)</p> |
|
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347 | <p>The most typical usage is like this:</p> |
|
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348 | <pre> if (!ev_default_loop (0)) |
|
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349 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
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350 | |
|
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351 | </pre> |
|
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352 | <p>Restrict libev to the select and poll backends, and do not allow |
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353 | environment settings to be taken into account:</p> |
|
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354 | <pre> ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
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355 | |
|
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356 | </pre> |
|
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357 | <p>Use whatever libev has to offer, but make sure that kqueue is used if |
|
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358 | available (warning, breaks stuff, best use only with your own private |
|
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359 | event loop and only if you know the OS supports your types of fds):</p> |
|
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360 | <pre> ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
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361 | |
|
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362 | </pre> |
202 | </dd> |
363 | </dd> |
203 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
364 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
204 | <dd> |
365 | <dd> |
205 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
366 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
206 | always distinct from the default loop. Unlike the default loop, it cannot |
367 | always distinct from the default loop. Unlike the default loop, it cannot |
207 | handle signal and child watchers, and attempts to do so will be greeted by |
368 | handle signal and child watchers, and attempts to do so will be greeted by |
208 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
369 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
|
|
370 | <p>Example: try to create a event loop that uses epoll and nothing else.</p> |
|
|
371 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
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372 | if (!epoller) |
|
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373 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
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374 | |
|
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375 | </pre> |
209 | </dd> |
376 | </dd> |
210 | <dt>ev_default_destroy ()</dt> |
377 | <dt>ev_default_destroy ()</dt> |
211 | <dd> |
378 | <dd> |
212 | <p>Destroys the default loop again (frees all memory and kernel state |
379 | <p>Destroys the default loop again (frees all memory and kernel state |
213 | etc.). This stops all registered event watchers (by not touching them in |
380 | etc.). None of the active event watchers will be stopped in the normal |
214 | any way whatsoever, although you cannot rely on this :).</p> |
381 | sense, so e.g. <code>ev_is_active</code> might still return true. It is your |
|
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382 | responsibility to either stop all watchers cleanly yoursef <i>before</i> |
|
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383 | calling this function, or cope with the fact afterwards (which is usually |
|
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384 | the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them |
|
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385 | for example).</p> |
215 | </dd> |
386 | </dd> |
216 | <dt>ev_loop_destroy (loop)</dt> |
387 | <dt>ev_loop_destroy (loop)</dt> |
217 | <dd> |
388 | <dd> |
218 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
389 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
219 | earlier call to <code>ev_loop_new</code>.</p> |
390 | earlier call to <code>ev_loop_new</code>.</p> |
… | |
… | |
222 | <dd> |
393 | <dd> |
223 | <p>This function reinitialises the kernel state for backends that have |
394 | <p>This function reinitialises the kernel state for backends that have |
224 | one. Despite the name, you can call it anytime, but it makes most sense |
395 | one. Despite the name, you can call it anytime, but it makes most sense |
225 | after forking, in either the parent or child process (or both, but that |
396 | after forking, in either the parent or child process (or both, but that |
226 | again makes little sense).</p> |
397 | again makes little sense).</p> |
227 | <p>You <i>must</i> call this function after forking if and only if you want to |
398 | <p>You <i>must</i> call this function in the child process after forking if and |
228 | use the event library in both processes. If you just fork+exec, you don't |
399 | only if you want to use the event library in both processes. If you just |
229 | have to call it.</p> |
400 | fork+exec, you don't have to call it.</p> |
230 | <p>The function itself is quite fast and it's usually not a problem to call |
401 | <p>The function itself is quite fast and it's usually not a problem to call |
231 | it just in case after a fork. To make this easy, the function will fit in |
402 | it just in case after a fork. To make this easy, the function will fit in |
232 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
403 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
233 | <pre> pthread_atfork (0, 0, ev_default_fork); |
404 | <pre> pthread_atfork (0, 0, ev_default_fork); |
234 | |
405 | |
235 | </pre> |
406 | </pre> |
|
|
407 | <p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use |
|
|
408 | without calling this function, so if you force one of those backends you |
|
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409 | do not need to care.</p> |
236 | </dd> |
410 | </dd> |
237 | <dt>ev_loop_fork (loop)</dt> |
411 | <dt>ev_loop_fork (loop)</dt> |
238 | <dd> |
412 | <dd> |
239 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
413 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
240 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
414 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
241 | after fork, and how you do this is entirely your own problem.</p> |
415 | after fork, and how you do this is entirely your own problem.</p> |
242 | </dd> |
416 | </dd> |
243 | <dt>unsigned int ev_method (loop)</dt> |
417 | <dt>unsigned int ev_backend (loop)</dt> |
244 | <dd> |
418 | <dd> |
245 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
419 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
246 | use.</p> |
420 | use.</p> |
247 | </dd> |
421 | </dd> |
248 | <dt>ev_tstamp ev_now (loop)</dt> |
422 | <dt>ev_tstamp ev_now (loop)</dt> |
249 | <dd> |
423 | <dd> |
250 | <p>Returns the current "event loop time", which is the time the event loop |
424 | <p>Returns the current "event loop time", which is the time the event loop |
251 | got events and started processing them. This timestamp does not change |
425 | received events and started processing them. This timestamp does not |
252 | as long as callbacks are being processed, and this is also the base time |
426 | change as long as callbacks are being processed, and this is also the base |
253 | used for relative timers. You can treat it as the timestamp of the event |
427 | time used for relative timers. You can treat it as the timestamp of the |
254 | occuring (or more correctly, the mainloop finding out about it).</p> |
428 | event occuring (or more correctly, libev finding out about it).</p> |
255 | </dd> |
429 | </dd> |
256 | <dt>ev_loop (loop, int flags)</dt> |
430 | <dt>ev_loop (loop, int flags)</dt> |
257 | <dd> |
431 | <dd> |
258 | <p>Finally, this is it, the event handler. This function usually is called |
432 | <p>Finally, this is it, the event handler. This function usually is called |
259 | after you initialised all your watchers and you want to start handling |
433 | after you initialised all your watchers and you want to start handling |
260 | events.</p> |
434 | events.</p> |
261 | <p>If the flags argument is specified as 0, it will not return until either |
435 | <p>If the flags argument is specified as <code>0</code>, it will not return until |
262 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
436 | either no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
|
|
437 | <p>Please note that an explicit <code>ev_unloop</code> is usually better than |
|
|
438 | relying on all watchers to be stopped when deciding when a program has |
|
|
439 | finished (especially in interactive programs), but having a program that |
|
|
440 | automatically loops as long as it has to and no longer by virtue of |
|
|
441 | relying on its watchers stopping correctly is a thing of beauty.</p> |
263 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
442 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
264 | those events and any outstanding ones, but will not block your process in |
443 | those events and any outstanding ones, but will not block your process in |
265 | case there are no events and will return after one iteration of the loop.</p> |
444 | case there are no events and will return after one iteration of the loop.</p> |
266 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
445 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
267 | neccessary) and will handle those and any outstanding ones. It will block |
446 | neccessary) and will handle those and any outstanding ones. It will block |
268 | your process until at least one new event arrives, and will return after |
447 | your process until at least one new event arrives, and will return after |
269 | one iteration of the loop.</p> |
448 | one iteration of the loop. This is useful if you are waiting for some |
270 | <p>This flags value could be used to implement alternative looping |
449 | external event in conjunction with something not expressible using other |
271 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
450 | libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is |
272 | more generic mechanism.</p> |
451 | usually a better approach for this kind of thing.</p> |
|
|
452 | <p>Here are the gory details of what <code>ev_loop</code> does:</p> |
|
|
453 | <pre> * If there are no active watchers (reference count is zero), return. |
|
|
454 | - Queue prepare watchers and then call all outstanding watchers. |
|
|
455 | - If we have been forked, recreate the kernel state. |
|
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456 | - Update the kernel state with all outstanding changes. |
|
|
457 | - Update the "event loop time". |
|
|
458 | - Calculate for how long to block. |
|
|
459 | - Block the process, waiting for any events. |
|
|
460 | - Queue all outstanding I/O (fd) events. |
|
|
461 | - Update the "event loop time" and do time jump handling. |
|
|
462 | - Queue all outstanding timers. |
|
|
463 | - Queue all outstanding periodics. |
|
|
464 | - If no events are pending now, queue all idle watchers. |
|
|
465 | - Queue all check watchers. |
|
|
466 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
467 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
468 | be handled here by queueing them when their watcher gets executed. |
|
|
469 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
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470 | were used, return, otherwise continue with step *. |
|
|
471 | |
|
|
472 | </pre> |
|
|
473 | <p>Example: queue some jobs and then loop until no events are outsanding |
|
|
474 | anymore.</p> |
|
|
475 | <pre> ... queue jobs here, make sure they register event watchers as long |
|
|
476 | ... as they still have work to do (even an idle watcher will do..) |
|
|
477 | ev_loop (my_loop, 0); |
|
|
478 | ... jobs done. yeah! |
|
|
479 | |
|
|
480 | </pre> |
273 | </dd> |
481 | </dd> |
274 | <dt>ev_unloop (loop, how)</dt> |
482 | <dt>ev_unloop (loop, how)</dt> |
275 | <dd> |
483 | <dd> |
276 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
484 | <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 |
485 | has processed all outstanding events). The <code>how</code> argument must be either |
278 | <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> call return, or |
486 | <code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or |
279 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
487 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
280 | </dd> |
488 | </dd> |
281 | <dt>ev_ref (loop)</dt> |
489 | <dt>ev_ref (loop)</dt> |
282 | <dt>ev_unref (loop)</dt> |
490 | <dt>ev_unref (loop)</dt> |
283 | <dd> |
491 | <dd> |
… | |
… | |
289 | example, libev itself uses this for its internal signal pipe: It is not |
497 | example, libev itself uses this for its internal signal pipe: It is not |
290 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
498 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
291 | no event watchers registered by it are active. It is also an excellent |
499 | no event watchers registered by it are active. It is also an excellent |
292 | way to do this for generic recurring timers or from within third-party |
500 | 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> |
501 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
|
|
502 | <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> |
|
|
503 | running when nothing else is active.</p> |
|
|
504 | <pre> struct dv_signal exitsig; |
|
|
505 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
506 | ev_signal_start (myloop, &exitsig); |
|
|
507 | evf_unref (myloop); |
|
|
508 | |
|
|
509 | </pre> |
|
|
510 | <p>Example: for some weird reason, unregister the above signal handler again.</p> |
|
|
511 | <pre> ev_ref (myloop); |
|
|
512 | ev_signal_stop (myloop, &exitsig); |
|
|
513 | |
|
|
514 | </pre> |
294 | </dd> |
515 | </dd> |
295 | </dl> |
516 | </dl> |
|
|
517 | |
|
|
518 | |
|
|
519 | |
|
|
520 | |
296 | |
521 | |
297 | </div> |
522 | </div> |
298 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
523 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
299 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
524 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
300 | <p>A watcher is a structure that you create and register to record your |
525 | <p>A watcher is a structure that you create and register to record your |
… | |
… | |
330 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
555 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
331 | *)</code>), and you can stop watching for events at any time by calling the |
556 | *)</code>), and you can stop watching for events at any time by calling the |
332 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
557 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
333 | <p>As long as your watcher is active (has been started but not stopped) you |
558 | <p>As long as your watcher is active (has been started but not stopped) you |
334 | must not touch the values stored in it. Most specifically you must never |
559 | must not touch the values stored in it. Most specifically you must never |
335 | reinitialise it or call its set method.</p> |
560 | reinitialise it or call its <code>set</code> macro.</p> |
336 | <p>You can check whether an event is active by calling the <code>ev_is_active |
|
|
337 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
|
|
338 | callback for it has not been called yet) you can use the <code>ev_is_pending |
|
|
339 | (watcher *)</code> macro.</p> |
|
|
340 | <p>Each and every callback receives the event loop pointer as first, the |
561 | <p>Each and every callback receives the event loop pointer as first, the |
341 | registered watcher structure as second, and a bitset of received events as |
562 | registered watcher structure as second, and a bitset of received events as |
342 | third argument.</p> |
563 | third argument.</p> |
343 | <p>The received events usually include a single bit per event type received |
564 | <p>The received events usually include a single bit per event type received |
344 | (you can receive multiple events at the same time). The possible bit masks |
565 | (you can receive multiple events at the same time). The possible bit masks |
… | |
… | |
393 | your callbacks is well-written it can just attempt the operation and cope |
614 | your callbacks is well-written it can just attempt the operation and cope |
394 | with the error from read() or write(). This will not work in multithreaded |
615 | with the error from read() or write(). This will not work in multithreaded |
395 | programs, though, so beware.</p> |
616 | programs, though, so beware.</p> |
396 | </dd> |
617 | </dd> |
397 | </dl> |
618 | </dl> |
|
|
619 | |
|
|
620 | </div> |
|
|
621 | <h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2> |
|
|
622 | <div id="GENERIC_WATCHER_FUNCTIONS_CONTENT"> |
|
|
623 | <p>In the following description, <code>TYPE</code> stands for the watcher type, |
|
|
624 | e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> |
|
|
625 | <dl> |
|
|
626 | <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> |
|
|
627 | <dd> |
|
|
628 | <p>This macro initialises the generic portion of a watcher. The contents |
|
|
629 | of the watcher object can be arbitrary (so <code>malloc</code> will do). Only |
|
|
630 | the generic parts of the watcher are initialised, you <i>need</i> to call |
|
|
631 | the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the |
|
|
632 | type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro |
|
|
633 | which rolls both calls into one.</p> |
|
|
634 | <p>You can reinitialise a watcher at any time as long as it has been stopped |
|
|
635 | (or never started) and there are no pending events outstanding.</p> |
|
|
636 | <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
637 | int revents)</code>.</p> |
|
|
638 | </dd> |
|
|
639 | <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> |
|
|
640 | <dd> |
|
|
641 | <p>This macro initialises the type-specific parts of a watcher. You need to |
|
|
642 | call <code>ev_init</code> at least once before you call this macro, but you can |
|
|
643 | call <code>ev_TYPE_set</code> any number of times. You must not, however, call this |
|
|
644 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
645 | difference to the <code>ev_init</code> macro).</p> |
|
|
646 | <p>Although some watcher types do not have type-specific arguments |
|
|
647 | (e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p> |
|
|
648 | </dd> |
|
|
649 | <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt> |
|
|
650 | <dd> |
|
|
651 | <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro |
|
|
652 | calls into a single call. This is the most convinient method to initialise |
|
|
653 | a watcher. The same limitations apply, of course.</p> |
|
|
654 | </dd> |
|
|
655 | <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
656 | <dd> |
|
|
657 | <p>Starts (activates) the given watcher. Only active watchers will receive |
|
|
658 | events. If the watcher is already active nothing will happen.</p> |
|
|
659 | </dd> |
|
|
660 | <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
661 | <dd> |
|
|
662 | <p>Stops the given watcher again (if active) and clears the pending |
|
|
663 | status. It is possible that stopped watchers are pending (for example, |
|
|
664 | non-repeating timers are being stopped when they become pending), but |
|
|
665 | <code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If |
|
|
666 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
667 | good idea to always call its <code>ev_TYPE_stop</code> function.</p> |
|
|
668 | </dd> |
|
|
669 | <dt>bool ev_is_active (ev_TYPE *watcher)</dt> |
|
|
670 | <dd> |
|
|
671 | <p>Returns a true value iff the watcher is active (i.e. it has been started |
|
|
672 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
673 | it.</p> |
|
|
674 | </dd> |
|
|
675 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
|
|
676 | <dd> |
|
|
677 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
678 | events but its callback has not yet been invoked). As long as a watcher |
|
|
679 | is pending (but not active) you must not call an init function on it (but |
|
|
680 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
|
|
681 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
|
|
682 | </dd> |
|
|
683 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
|
|
684 | <dd> |
|
|
685 | <p>Returns the callback currently set on the watcher.</p> |
|
|
686 | </dd> |
|
|
687 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
|
|
688 | <dd> |
|
|
689 | <p>Change the callback. You can change the callback at virtually any time |
|
|
690 | (modulo threads).</p> |
|
|
691 | </dd> |
|
|
692 | </dl> |
|
|
693 | |
|
|
694 | |
|
|
695 | |
|
|
696 | |
398 | |
697 | |
399 | </div> |
698 | </div> |
400 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
699 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
401 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
700 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
402 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
701 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
… | |
… | |
434 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
733 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
435 | <div id="WATCHER_TYPES_CONTENT"> |
734 | <div id="WATCHER_TYPES_CONTENT"> |
436 | <p>This section describes each watcher in detail, but will not repeat |
735 | <p>This section describes each watcher in detail, but will not repeat |
437 | information given in the last section.</p> |
736 | information given in the last section.</p> |
438 | |
737 | |
|
|
738 | |
|
|
739 | |
|
|
740 | |
|
|
741 | |
439 | </div> |
742 | </div> |
440 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
743 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2> |
441 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
744 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
442 | <p>I/O watchers check whether a file descriptor is readable or writable |
745 | <p>I/O watchers check whether a file descriptor is readable or writable |
443 | in each iteration of the event loop (This behaviour is called |
746 | in each iteration of the event loop, or, more precisely, when reading |
444 | level-triggering because you keep receiving events as long as the |
747 | would not block the process and writing would at least be able to write |
445 | condition persists. Remember you can stop the watcher if you don't want to |
748 | some data. This behaviour is called level-triggering because you keep |
446 | act on the event and neither want to receive future events).</p> |
749 | receiving events as long as the condition persists. Remember you can stop |
|
|
750 | the watcher if you don't want to act on the event and neither want to |
|
|
751 | receive future events.</p> |
447 | <p>In general you can register as many read and/or write event watchers oer |
752 | <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 |
753 | 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 |
754 | descriptors to non-blocking mode is also usually a good idea (but not |
450 | required if you know what you are doing).</p> |
755 | required if you know what you are doing).</p> |
451 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
756 | <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 |
757 | (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 |
758 | descriptors correctly if you register interest in two or more fds pointing |
454 | to the same file/socket etc. description.</p> |
759 | to the same underlying file/socket/etc. description (that is, they share |
|
|
760 | the same underlying "file open").</p> |
455 | <p>If you must do this, then force the use of a known-to-be-good backend |
761 | <p>If you must do this, then force the use of a known-to-be-good backend |
456 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
762 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
457 | EVMETHOD_POLL).</p> |
763 | <code>EVBACKEND_POLL</code>).</p> |
|
|
764 | <p>Another thing you have to watch out for is that it is quite easy to |
|
|
765 | receive "spurious" readyness notifications, that is your callback might |
|
|
766 | be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block |
|
|
767 | because there is no data. Not only are some backends known to create a |
|
|
768 | lot of those (for example solaris ports), it is very easy to get into |
|
|
769 | this situation even with a relatively standard program structure. Thus |
|
|
770 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
|
|
771 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
|
|
772 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
|
|
773 | play around with an Xlib connection), then you have to seperately re-test |
|
|
774 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
775 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
776 | its own, so its quite safe to use).</p> |
458 | <dl> |
777 | <dl> |
459 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
778 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
460 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
779 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
461 | <dd> |
780 | <dd> |
462 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
781 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
463 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
782 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
464 | EV_WRITE</code> to receive the given events.</p> |
783 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
465 | </dd> |
784 | </dd> |
466 | </dl> |
785 | </dl> |
|
|
786 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
|
|
787 | readable, but only once. Since it is likely line-buffered, you could |
|
|
788 | attempt to read a whole line in the callback:</p> |
|
|
789 | <pre> static void |
|
|
790 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
791 | { |
|
|
792 | ev_io_stop (loop, w); |
|
|
793 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
794 | } |
467 | |
795 | |
|
|
796 | ... |
|
|
797 | struct ev_loop *loop = ev_default_init (0); |
|
|
798 | struct ev_io stdin_readable; |
|
|
799 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
800 | ev_io_start (loop, &stdin_readable); |
|
|
801 | ev_loop (loop, 0); |
|
|
802 | |
|
|
803 | |
|
|
804 | |
|
|
805 | |
|
|
806 | </pre> |
|
|
807 | |
468 | </div> |
808 | </div> |
469 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
809 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2> |
470 | <div id="code_ev_timer_code_relative_and_opti-2"> |
810 | <div id="code_ev_timer_code_relative_and_opti-2"> |
471 | <p>Timer watchers are simple relative timers that generate an event after a |
811 | <p>Timer watchers are simple relative timers that generate an event after a |
472 | given time, and optionally repeating in regular intervals after that.</p> |
812 | given time, and optionally repeating in regular intervals after that.</p> |
473 | <p>The timers are based on real time, that is, if you register an event that |
813 | <p>The timers are based on real time, that is, if you register an event that |
474 | times out after an hour and youreset your system clock to last years |
814 | times out after an hour and you reset your system clock to last years |
475 | time, it will still time out after (roughly) and hour. "Roughly" because |
815 | time, it will still time out after (roughly) and hour. "Roughly" because |
476 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
816 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
477 | monotonic clock option helps a lot here).</p> |
817 | monotonic clock option helps a lot here).</p> |
478 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
818 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
479 | time. This is usually the right thing as this timestamp refers to the time |
819 | time. This is usually the right thing as this timestamp refers to the time |
480 | of the event triggering whatever timeout you are modifying/starting. If |
820 | of the event triggering whatever timeout you are modifying/starting. If |
481 | you suspect event processing to be delayed and you *need* to base the timeout |
821 | you suspect event processing to be delayed and you <i>need</i> to base the timeout |
482 | ion the current time, use something like this to adjust for this:</p> |
822 | on the current time, use something like this to adjust for this:</p> |
483 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
823 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
484 | |
824 | |
485 | </pre> |
825 | </pre> |
|
|
826 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
827 | but if multiple timers become ready during the same loop iteration then |
|
|
828 | order of execution is undefined.</p> |
486 | <dl> |
829 | <dl> |
487 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
830 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
488 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
831 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
489 | <dd> |
832 | <dd> |
490 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
833 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
492 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
835 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
493 | later, again, and again, until stopped manually.</p> |
836 | later, again, and again, until stopped manually.</p> |
494 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
837 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
495 | configure a timer to trigger every 10 seconds, then it will trigger at |
838 | configure a timer to trigger every 10 seconds, then it will trigger at |
496 | exactly 10 second intervals. If, however, your program cannot keep up with |
839 | exactly 10 second intervals. If, however, your program cannot keep up with |
497 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
840 | the timer (because it takes longer than those 10 seconds to do stuff) the |
498 | timer will not fire more than once per event loop iteration.</p> |
841 | timer will not fire more than once per event loop iteration.</p> |
499 | </dd> |
842 | </dd> |
500 | <dt>ev_timer_again (loop)</dt> |
843 | <dt>ev_timer_again (loop)</dt> |
501 | <dd> |
844 | <dd> |
502 | <p>This will act as if the timer timed out and restart it again if it is |
845 | <p>This will act as if the timer timed out and restart it again if it is |
… | |
… | |
512 | time you successfully read or write some data. If you go into an idle |
855 | time you successfully read or write some data. If you go into an idle |
513 | state where you do not expect data to travel on the socket, you can stop |
856 | state where you do not expect data to travel on the socket, you can stop |
514 | the timer, and again will automatically restart it if need be.</p> |
857 | the timer, and again will automatically restart it if need be.</p> |
515 | </dd> |
858 | </dd> |
516 | </dl> |
859 | </dl> |
|
|
860 | <p>Example: create a timer that fires after 60 seconds.</p> |
|
|
861 | <pre> static void |
|
|
862 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
863 | { |
|
|
864 | .. one minute over, w is actually stopped right here |
|
|
865 | } |
517 | |
866 | |
|
|
867 | struct ev_timer mytimer; |
|
|
868 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
869 | ev_timer_start (loop, &mytimer); |
|
|
870 | |
|
|
871 | </pre> |
|
|
872 | <p>Example: create a timeout timer that times out after 10 seconds of |
|
|
873 | inactivity.</p> |
|
|
874 | <pre> static void |
|
|
875 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
876 | { |
|
|
877 | .. ten seconds without any activity |
|
|
878 | } |
|
|
879 | |
|
|
880 | struct ev_timer mytimer; |
|
|
881 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
882 | ev_timer_again (&mytimer); /* start timer */ |
|
|
883 | ev_loop (loop, 0); |
|
|
884 | |
|
|
885 | // and in some piece of code that gets executed on any "activity": |
|
|
886 | // reset the timeout to start ticking again at 10 seconds |
|
|
887 | ev_timer_again (&mytimer); |
|
|
888 | |
|
|
889 | |
|
|
890 | |
|
|
891 | |
|
|
892 | </pre> |
|
|
893 | |
518 | </div> |
894 | </div> |
519 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
895 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2> |
520 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
896 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
521 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
897 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
522 | (and unfortunately a bit complex).</p> |
898 | (and unfortunately a bit complex).</p> |
523 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
899 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
524 | but on wallclock time (absolute time). You can tell a periodic watcher |
900 | but on wallclock time (absolute time). You can tell a periodic watcher |
525 | to trigger "at" some specific point in time. For example, if you tell a |
901 | to trigger "at" some specific point in time. For example, if you tell a |
526 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
902 | periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () |
527 | + 10.>) and then reset your system clock to the last year, then it will |
903 | + 10.</code>) and then reset your system clock to the last year, then it will |
528 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
904 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
529 | roughly 10 seconds later and of course not if you reset your system time |
905 | roughly 10 seconds later and of course not if you reset your system time |
530 | again).</p> |
906 | again).</p> |
531 | <p>They can also be used to implement vastly more complex timers, such as |
907 | <p>They can also be used to implement vastly more complex timers, such as |
532 | triggering an event on eahc midnight, local time.</p> |
908 | triggering an event on eahc midnight, local time.</p> |
|
|
909 | <p>As with timers, the callback is guarenteed to be invoked only when the |
|
|
910 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
|
|
911 | during the same loop iteration then order of execution is undefined.</p> |
533 | <dl> |
912 | <dl> |
534 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
913 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
535 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
914 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
536 | <dd> |
915 | <dd> |
537 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
916 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
538 | operation, and we will explain them from simplest to complex:</p> |
917 | operation, and we will explain them from simplest to complex:</p> |
539 | |
|
|
540 | |
|
|
541 | |
|
|
542 | |
|
|
543 | <p> |
918 | <p> |
544 | <dl> |
919 | <dl> |
545 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
920 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
546 | <dd> |
921 | <dd> |
547 | <p>In this configuration the watcher triggers an event at the wallclock time |
922 | <p>In this configuration the watcher triggers an event at the wallclock time |
… | |
… | |
606 | when you changed some parameters or the reschedule callback would return |
981 | when you changed some parameters or the reschedule callback would return |
607 | a different time than the last time it was called (e.g. in a crond like |
982 | a different time than the last time it was called (e.g. in a crond like |
608 | program when the crontabs have changed).</p> |
983 | program when the crontabs have changed).</p> |
609 | </dd> |
984 | </dd> |
610 | </dl> |
985 | </dl> |
|
|
986 | <p>Example: call a callback every hour, or, more precisely, whenever the |
|
|
987 | system clock is divisible by 3600. The callback invocation times have |
|
|
988 | potentially a lot of jittering, but good long-term stability.</p> |
|
|
989 | <pre> static void |
|
|
990 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
991 | { |
|
|
992 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
993 | } |
611 | |
994 | |
|
|
995 | struct ev_periodic hourly_tick; |
|
|
996 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
997 | ev_periodic_start (loop, &hourly_tick); |
|
|
998 | |
|
|
999 | </pre> |
|
|
1000 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
|
|
1001 | <pre> #include <math.h> |
|
|
1002 | |
|
|
1003 | static ev_tstamp |
|
|
1004 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1005 | { |
|
|
1006 | return fmod (now, 3600.) + 3600.; |
|
|
1007 | } |
|
|
1008 | |
|
|
1009 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1010 | |
|
|
1011 | </pre> |
|
|
1012 | <p>Example: call a callback every hour, starting now:</p> |
|
|
1013 | <pre> struct ev_periodic hourly_tick; |
|
|
1014 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1015 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1016 | ev_periodic_start (loop, &hourly_tick); |
|
|
1017 | |
|
|
1018 | |
|
|
1019 | |
|
|
1020 | |
|
|
1021 | </pre> |
|
|
1022 | |
612 | </div> |
1023 | </div> |
613 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
1024 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2> |
614 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
1025 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
615 | <p>Signal watchers will trigger an event when the process receives a specific |
1026 | <p>Signal watchers will trigger an event when the process receives a specific |
616 | signal one or more times. Even though signals are very asynchronous, libev |
1027 | signal one or more times. Even though signals are very asynchronous, libev |
617 | will try it's best to deliver signals synchronously, i.e. as part of the |
1028 | will try it's best to deliver signals synchronously, i.e. as part of the |
618 | normal event processing, like any other event.</p> |
1029 | normal event processing, like any other event.</p> |
… | |
… | |
629 | <p>Configures the watcher to trigger on the given signal number (usually one |
1040 | <p>Configures the watcher to trigger on the given signal number (usually one |
630 | of the <code>SIGxxx</code> constants).</p> |
1041 | of the <code>SIGxxx</code> constants).</p> |
631 | </dd> |
1042 | </dd> |
632 | </dl> |
1043 | </dl> |
633 | |
1044 | |
|
|
1045 | |
|
|
1046 | |
|
|
1047 | |
|
|
1048 | |
634 | </div> |
1049 | </div> |
635 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
1050 | <h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> |
636 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
1051 | <div id="code_ev_child_code_watch_out_for_pro-2"> |
637 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1052 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
638 | some child status changes (most typically when a child of yours dies).</p> |
1053 | some child status changes (most typically when a child of yours dies).</p> |
639 | <dl> |
1054 | <dl> |
640 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1055 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
641 | <dt>ev_child_set (ev_child *, int pid)</dt> |
1056 | <dt>ev_child_set (ev_child *, int pid)</dt> |
… | |
… | |
646 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1061 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
647 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1062 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
648 | process causing the status change.</p> |
1063 | process causing the status change.</p> |
649 | </dd> |
1064 | </dd> |
650 | </dl> |
1065 | </dl> |
|
|
1066 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
|
|
1067 | <pre> static void |
|
|
1068 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1069 | { |
|
|
1070 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1071 | } |
651 | |
1072 | |
|
|
1073 | struct ev_signal signal_watcher; |
|
|
1074 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1075 | ev_signal_start (loop, &sigint_cb); |
|
|
1076 | |
|
|
1077 | |
|
|
1078 | |
|
|
1079 | |
|
|
1080 | </pre> |
|
|
1081 | |
652 | </div> |
1082 | </div> |
653 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
1083 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
654 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1084 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
655 | <p>Idle watchers trigger events when there are no other events are pending |
1085 | <p>Idle watchers trigger events when there are no other events are pending |
656 | (prepare, check and other idle watchers do not count). That is, as long |
1086 | (prepare, check and other idle watchers do not count). That is, as long |
657 | as your process is busy handling sockets or timeouts (or even signals, |
1087 | as your process is busy handling sockets or timeouts (or even signals, |
658 | imagine) it will not be triggered. But when your process is idle all idle |
1088 | imagine) it will not be triggered. But when your process is idle all idle |
… | |
… | |
671 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1101 | <p>Initialises and configures the idle watcher - it has no parameters of any |
672 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1102 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
673 | believe me.</p> |
1103 | believe me.</p> |
674 | </dd> |
1104 | </dd> |
675 | </dl> |
1105 | </dl> |
|
|
1106 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
|
|
1107 | callback, free it. Alos, use no error checking, as usual.</p> |
|
|
1108 | <pre> static void |
|
|
1109 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1110 | { |
|
|
1111 | free (w); |
|
|
1112 | // now do something you wanted to do when the program has |
|
|
1113 | // no longer asnything immediate to do. |
|
|
1114 | } |
676 | |
1115 | |
|
|
1116 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1117 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1118 | ev_idle_start (loop, idle_cb); |
|
|
1119 | |
|
|
1120 | |
|
|
1121 | |
|
|
1122 | |
|
|
1123 | </pre> |
|
|
1124 | |
677 | </div> |
1125 | </div> |
678 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
1126 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2> |
679 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1127 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
680 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1128 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
681 | prepare watchers get invoked before the process blocks and check watchers |
1129 | prepare watchers get invoked before the process blocks and check watchers |
682 | afterwards.</p> |
1130 | afterwards.</p> |
683 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
1131 | <p>Their main purpose is to integrate other event mechanisms into libev and |
684 | could be used, for example, to track variable changes, implement your own |
1132 | their use is somewhat advanced. This could be used, for example, to track |
685 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
1133 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1134 | coroutine library and lots more.</p> |
686 | <p>This is done by examining in each prepare call which file descriptors need |
1135 | <p>This is done by examining in each prepare call which file descriptors need |
687 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1136 | to be watched by the other library, registering <code>ev_io</code> watchers for |
688 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1137 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
689 | provide just this functionality). Then, in the check watcher you check for |
1138 | provide just this functionality). Then, in the check watcher you check for |
690 | any events that occured (by checking the pending status of all watchers |
1139 | any events that occured (by checking the pending status of all watchers |
… | |
… | |
706 | <p>Initialises and configures the prepare or check watcher - they have no |
1155 | <p>Initialises and configures the prepare or check watcher - they have no |
707 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1156 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
708 | macros, but using them is utterly, utterly and completely pointless.</p> |
1157 | macros, but using them is utterly, utterly and completely pointless.</p> |
709 | </dd> |
1158 | </dd> |
710 | </dl> |
1159 | </dl> |
|
|
1160 | <p>Example: *TODO*.</p> |
|
|
1161 | |
|
|
1162 | |
|
|
1163 | |
|
|
1164 | |
|
|
1165 | |
|
|
1166 | </div> |
|
|
1167 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2> |
|
|
1168 | <div id="code_ev_embed_code_when_one_backend_-2"> |
|
|
1169 | <p>This is a rather advanced watcher type that lets you embed one event loop |
|
|
1170 | into another (currently only <code>ev_io</code> events are supported in the embedded |
|
|
1171 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1172 | fashion and must not be used).</p> |
|
|
1173 | <p>There are primarily two reasons you would want that: work around bugs and |
|
|
1174 | prioritise I/O.</p> |
|
|
1175 | <p>As an example for a bug workaround, the kqueue backend might only support |
|
|
1176 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1177 | still want to make use of it because you have many sockets and it scales |
|
|
1178 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1179 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1180 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1181 | at least you can use both at what they are best.</p> |
|
|
1182 | <p>As for prioritising I/O: rarely you have the case where some fds have |
|
|
1183 | to be watched and handled very quickly (with low latency), and even |
|
|
1184 | priorities and idle watchers might have too much overhead. In this case |
|
|
1185 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1186 | a second one, and embed the second one in the first.</p> |
|
|
1187 | <p>As long as the watcher is active, the callback will be invoked every time |
|
|
1188 | there might be events pending in the embedded loop. The callback must then |
|
|
1189 | call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke |
|
|
1190 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1191 | loop strictly lower priority for example). You can also set the callback |
|
|
1192 | to <code>0</code>, in which case the embed watcher will automatically execute the |
|
|
1193 | embedded loop sweep.</p> |
|
|
1194 | <p>As long as the watcher is started it will automatically handle events. The |
|
|
1195 | callback will be invoked whenever some events have been handled. You can |
|
|
1196 | set the callback to <code>0</code> to avoid having to specify one if you are not |
|
|
1197 | interested in that.</p> |
|
|
1198 | <p>Also, there have not currently been made special provisions for forking: |
|
|
1199 | when you fork, you not only have to call <code>ev_loop_fork</code> on both loops, |
|
|
1200 | but you will also have to stop and restart any <code>ev_embed</code> watchers |
|
|
1201 | yourself.</p> |
|
|
1202 | <p>Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1203 | <code>ev_embeddable_backends</code> are, which, unfortunately, does not include any |
|
|
1204 | portable one.</p> |
|
|
1205 | <p>So when you want to use this feature you will always have to be prepared |
|
|
1206 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1207 | this is to have a separate variables for your embeddable loop, try to |
|
|
1208 | create it, and if that fails, use the normal loop for everything:</p> |
|
|
1209 | <pre> struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1210 | struct ev_loop *loop_lo = 0; |
|
|
1211 | struct ev_embed embed; |
|
|
1212 | |
|
|
1213 | // see if there is a chance of getting one that works |
|
|
1214 | // (remember that a flags value of 0 means autodetection) |
|
|
1215 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1216 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1217 | : 0; |
|
|
1218 | |
|
|
1219 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1220 | if (loop_lo) |
|
|
1221 | { |
|
|
1222 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1223 | ev_embed_start (loop_hi, &embed); |
|
|
1224 | } |
|
|
1225 | else |
|
|
1226 | loop_lo = loop_hi; |
|
|
1227 | |
|
|
1228 | </pre> |
|
|
1229 | <dl> |
|
|
1230 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1231 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1232 | <dd> |
|
|
1233 | <p>Configures the watcher to embed the given loop, which must be |
|
|
1234 | embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be |
|
|
1235 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1236 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1237 | if you do not want thta, you need to temporarily stop the embed watcher).</p> |
|
|
1238 | </dd> |
|
|
1239 | <dt>ev_embed_sweep (loop, ev_embed *)</dt> |
|
|
1240 | <dd> |
|
|
1241 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1242 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
|
|
1243 | apropriate way for embedded loops.</p> |
|
|
1244 | </dd> |
|
|
1245 | </dl> |
|
|
1246 | |
|
|
1247 | |
|
|
1248 | |
|
|
1249 | |
711 | |
1250 | |
712 | </div> |
1251 | </div> |
713 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1252 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
714 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1253 | <div id="OTHER_FUNCTIONS_CONTENT"> |
715 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1254 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
… | |
… | |
717 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1256 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
718 | <dd> |
1257 | <dd> |
719 | <p>This function combines a simple timer and an I/O watcher, calls your |
1258 | <p>This function combines a simple timer and an I/O watcher, calls your |
720 | callback on whichever event happens first and automatically stop both |
1259 | callback on whichever event happens first and automatically stop both |
721 | watchers. This is useful if you want to wait for a single event on an fd |
1260 | watchers. This is useful if you want to wait for a single event on an fd |
722 | or timeout without havign to allocate/configure/start/stop/free one or |
1261 | or timeout without having to allocate/configure/start/stop/free one or |
723 | more watchers yourself.</p> |
1262 | more watchers yourself.</p> |
724 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events |
1263 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events |
725 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
1264 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
726 | <code>events</code> set will be craeted and started.</p> |
1265 | <code>events</code> set will be craeted and started.</p> |
727 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
1266 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
728 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
1267 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
729 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
1268 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
730 | dubious value.</p> |
1269 | dubious value.</p> |
731 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets |
1270 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets |
732 | passed an events set like normal event callbacks (with a combination of |
1271 | passed an <code>revents</code> set like normal event callbacks (a combination of |
733 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
1272 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
734 | value passed to <code>ev_once</code>:</p> |
1273 | value passed to <code>ev_once</code>:</p> |
735 | <pre> static void stdin_ready (int revents, void *arg) |
1274 | <pre> static void stdin_ready (int revents, void *arg) |
736 | { |
1275 | { |
737 | if (revents & EV_TIMEOUT) |
1276 | if (revents & EV_TIMEOUT) |
… | |
… | |
742 | |
1281 | |
743 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1282 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
744 | |
1283 | |
745 | </pre> |
1284 | </pre> |
746 | </dd> |
1285 | </dd> |
747 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
1286 | <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt> |
748 | <dd> |
1287 | <dd> |
749 | <p>Feeds the given event set into the event loop, as if the specified event |
1288 | <p>Feeds the given event set into the event loop, as if the specified event |
750 | had happened for the specified watcher (which must be a pointer to an |
1289 | had happened for the specified watcher (which must be a pointer to an |
751 | initialised but not necessarily started event watcher).</p> |
1290 | initialised but not necessarily started event watcher).</p> |
752 | </dd> |
1291 | </dd> |
753 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
1292 | <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt> |
754 | <dd> |
1293 | <dd> |
755 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
1294 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
756 | the given events it.</p> |
1295 | the given events it.</p> |
757 | </dd> |
1296 | </dd> |
758 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
1297 | <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt> |
759 | <dd> |
1298 | <dd> |
760 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
1299 | <p>Feed an event as if the given signal occured (<code>loop</code> must be the default |
|
|
1300 | loop!).</p> |
761 | </dd> |
1301 | </dd> |
762 | </dl> |
1302 | </dl> |
|
|
1303 | |
|
|
1304 | |
|
|
1305 | |
|
|
1306 | |
763 | |
1307 | |
764 | </div> |
1308 | </div> |
765 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1309 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
766 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1310 | <div id="LIBEVENT_EMULATION_CONTENT"> |
767 | <p>TBD.</p> |
1311 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
1312 | emulate the internals of libevent, so here are some usage hints:</p> |
|
|
1313 | <dl> |
|
|
1314 | <dt>* Use it by including <event.h>, as usual.</dt> |
|
|
1315 | <dt>* The following members are fully supported: ev_base, ev_callback, |
|
|
1316 | ev_arg, ev_fd, ev_res, ev_events.</dt> |
|
|
1317 | <dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
1318 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
1319 | it a private API).</dt> |
|
|
1320 | <dt>* Priorities are not currently supported. Initialising priorities |
|
|
1321 | will fail and all watchers will have the same priority, even though there |
|
|
1322 | is an ev_pri field.</dt> |
|
|
1323 | <dt>* Other members are not supported.</dt> |
|
|
1324 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
|
|
1325 | to use the libev header file and library.</dt> |
|
|
1326 | </dl> |
768 | |
1327 | |
769 | </div> |
1328 | </div> |
770 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1329 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
771 | <div id="C_SUPPORT_CONTENT"> |
1330 | <div id="C_SUPPORT_CONTENT"> |
772 | <p>TBD.</p> |
1331 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1332 | you to use some convinience methods to start/stop watchers and also change |
|
|
1333 | the callback model to a model using method callbacks on objects.</p> |
|
|
1334 | <p>To use it,</p> |
|
|
1335 | <pre> #include <ev++.h> |
|
|
1336 | |
|
|
1337 | </pre> |
|
|
1338 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
|
|
1339 | and puts all of its definitions (many of them macros) into the global |
|
|
1340 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
|
|
1341 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
|
|
1342 | <code>EV_MULTIPLICITY</code>.</p> |
|
|
1343 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
|
|
1344 | <dl> |
|
|
1345 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
|
|
1346 | <dd> |
|
|
1347 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
|
|
1348 | macros from <cite>ev.h</cite>.</p> |
|
|
1349 | </dd> |
|
|
1350 | <dt><code>ev::tstamp</code>, <code>ev::now</code></dt> |
|
|
1351 | <dd> |
|
|
1352 | <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p> |
|
|
1353 | </dd> |
|
|
1354 | <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt> |
|
|
1355 | <dd> |
|
|
1356 | <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of |
|
|
1357 | the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code> |
|
|
1358 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
|
|
1359 | defines by many implementations.</p> |
|
|
1360 | <p>All of those classes have these methods:</p> |
|
|
1361 | <p> |
|
|
1362 | <dl> |
|
|
1363 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
|
|
1364 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
|
|
1365 | <dt>ev::TYPE::~TYPE</dt> |
|
|
1366 | <dd> |
|
|
1367 | <p>The constructor takes a pointer to an object and a method pointer to |
|
|
1368 | the event handler callback to call in this class. The constructor calls |
|
|
1369 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
|
|
1370 | before starting it. If you do not specify a loop then the constructor |
|
|
1371 | automatically associates the default loop with this watcher.</p> |
|
|
1372 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1373 | </dd> |
|
|
1374 | <dt>w->set (struct ev_loop *)</dt> |
|
|
1375 | <dd> |
|
|
1376 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
|
|
1377 | do this when the watcher is inactive (and not pending either).</p> |
|
|
1378 | </dd> |
|
|
1379 | <dt>w->set ([args])</dt> |
|
|
1380 | <dd> |
|
|
1381 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
|
|
1382 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1383 | automatically stopped and restarted.</p> |
|
|
1384 | </dd> |
|
|
1385 | <dt>w->start ()</dt> |
|
|
1386 | <dd> |
|
|
1387 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
|
|
1388 | constructor already takes the loop.</p> |
|
|
1389 | </dd> |
|
|
1390 | <dt>w->stop ()</dt> |
|
|
1391 | <dd> |
|
|
1392 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
|
|
1393 | </dd> |
|
|
1394 | <dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt> |
|
|
1395 | <dd> |
|
|
1396 | <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding |
|
|
1397 | <code>ev_TYPE_again</code> function.</p> |
|
|
1398 | </dd> |
|
|
1399 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
|
|
1400 | <dd> |
|
|
1401 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
|
|
1402 | </dd> |
|
|
1403 | </dl> |
|
|
1404 | </p> |
|
|
1405 | </dd> |
|
|
1406 | </dl> |
|
|
1407 | <p>Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1408 | the constructor.</p> |
|
|
1409 | <pre> class myclass |
|
|
1410 | { |
|
|
1411 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1412 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1413 | |
|
|
1414 | myclass (); |
|
|
1415 | } |
|
|
1416 | |
|
|
1417 | myclass::myclass (int fd) |
|
|
1418 | : io (this, &myclass::io_cb), |
|
|
1419 | idle (this, &myclass::idle_cb) |
|
|
1420 | { |
|
|
1421 | io.start (fd, ev::READ); |
|
|
1422 | } |
|
|
1423 | |
|
|
1424 | </pre> |
|
|
1425 | |
|
|
1426 | </div> |
|
|
1427 | <h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
1428 | <div id="EMBEDDING_CONTENT"> |
|
|
1429 | <p>Libev can (and often is) directly embedded into host |
|
|
1430 | applications. Examples of applications that embed it include the Deliantra |
|
|
1431 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1432 | and rxvt-unicode.</p> |
|
|
1433 | <p>The goal is to enable you to just copy the neecssary files into your |
|
|
1434 | source directory without having to change even a single line in them, so |
|
|
1435 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1436 | libev somewhere in your source tree).</p> |
|
|
1437 | |
|
|
1438 | </div> |
|
|
1439 | <h2 id="FILESETS">FILESETS</h2> |
|
|
1440 | <div id="FILESETS_CONTENT"> |
|
|
1441 | <p>Depending on what features you need you need to include one or more sets of files |
|
|
1442 | in your app.</p> |
|
|
1443 | |
|
|
1444 | </div> |
|
|
1445 | <h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3> |
|
|
1446 | <div id="CORE_EVENT_LOOP_CONTENT"> |
|
|
1447 | <p>To include only the libev core (all the <code>ev_*</code> functions), with manual |
|
|
1448 | configuration (no autoconf):</p> |
|
|
1449 | <pre> #define EV_STANDALONE 1 |
|
|
1450 | #include "ev.c" |
|
|
1451 | |
|
|
1452 | </pre> |
|
|
1453 | <p>This will automatically include <cite>ev.h</cite>, too, and should be done in a |
|
|
1454 | single C source file only to provide the function implementations. To use |
|
|
1455 | it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best |
|
|
1456 | done by writing a wrapper around <cite>ev.h</cite> that you can include instead and |
|
|
1457 | where you can put other configuration options):</p> |
|
|
1458 | <pre> #define EV_STANDALONE 1 |
|
|
1459 | #include "ev.h" |
|
|
1460 | |
|
|
1461 | </pre> |
|
|
1462 | <p>Both header files and implementation files can be compiled with a C++ |
|
|
1463 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1464 | as a bug).</p> |
|
|
1465 | <p>You need the following files in your source tree, or in a directory |
|
|
1466 | in your include path (e.g. in libev/ when using -Ilibev):</p> |
|
|
1467 | <pre> ev.h |
|
|
1468 | ev.c |
|
|
1469 | ev_vars.h |
|
|
1470 | ev_wrap.h |
|
|
1471 | |
|
|
1472 | ev_win32.c required on win32 platforms only |
|
|
1473 | |
|
|
1474 | ev_select.c only when select backend is enabled (which is is by default) |
|
|
1475 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1476 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1477 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1478 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1479 | |
|
|
1480 | </pre> |
|
|
1481 | <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need |
|
|
1482 | to compile a single file.</p> |
|
|
1483 | |
|
|
1484 | </div> |
|
|
1485 | <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> |
|
|
1486 | <div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> |
|
|
1487 | <p>To include the libevent compatibility API, also include:</p> |
|
|
1488 | <pre> #include "event.c" |
|
|
1489 | |
|
|
1490 | </pre> |
|
|
1491 | <p>in the file including <cite>ev.c</cite>, and:</p> |
|
|
1492 | <pre> #include "event.h" |
|
|
1493 | |
|
|
1494 | </pre> |
|
|
1495 | <p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p> |
|
|
1496 | <p>You need the following additional files for this:</p> |
|
|
1497 | <pre> event.h |
|
|
1498 | event.c |
|
|
1499 | |
|
|
1500 | </pre> |
|
|
1501 | |
|
|
1502 | </div> |
|
|
1503 | <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> |
|
|
1504 | <div id="AUTOCONF_SUPPORT_CONTENT"> |
|
|
1505 | <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in |
|
|
1506 | whatever way you want, you can also <code>m4_include([libev.m4])</code> in your |
|
|
1507 | <cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> off. <cite>ev.c</cite> will then include |
|
|
1508 | <cite>config.h</cite> and configure itself accordingly.</p> |
|
|
1509 | <p>For this of course you need the m4 file:</p> |
|
|
1510 | <pre> libev.m4 |
|
|
1511 | |
|
|
1512 | </pre> |
|
|
1513 | |
|
|
1514 | </div> |
|
|
1515 | <h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2> |
|
|
1516 | <div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT"> |
|
|
1517 | <p>Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1518 | before including any of its files. The default is not to build for multiplicity |
|
|
1519 | and only include the select backend.</p> |
|
|
1520 | <dl> |
|
|
1521 | <dt>EV_STANDALONE</dt> |
|
|
1522 | <dd> |
|
|
1523 | <p>Must always be <code>1</code> if you do not use autoconf configuration, which |
|
|
1524 | keeps libev from including <cite>config.h</cite>, and it also defines dummy |
|
|
1525 | implementations for some libevent functions (such as logging, which is not |
|
|
1526 | supported). It will also not define any of the structs usually found in |
|
|
1527 | <cite>event.h</cite> that are not directly supported by the libev core alone.</p> |
|
|
1528 | </dd> |
|
|
1529 | <dt>EV_USE_MONOTONIC</dt> |
|
|
1530 | <dd> |
|
|
1531 | <p>If defined to be <code>1</code>, libev will try to detect the availability of the |
|
|
1532 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1533 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1534 | usually have to link against librt or something similar. Enabling it when |
|
|
1535 | the functionality isn't available is safe, though, althoguh you have |
|
|
1536 | to make sure you link against any libraries where the <code>clock_gettime</code> |
|
|
1537 | function is hiding in (often <cite>-lrt</cite>).</p> |
|
|
1538 | </dd> |
|
|
1539 | <dt>EV_USE_REALTIME</dt> |
|
|
1540 | <dd> |
|
|
1541 | <p>If defined to be <code>1</code>, libev will try to detect the availability of the |
|
|
1542 | realtime clock option at compiletime (and assume its availability at |
|
|
1543 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1544 | be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get |
|
|
1545 | (CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries |
|
|
1546 | in the description of <code>EV_USE_MONOTONIC</code>, though.</p> |
|
|
1547 | </dd> |
|
|
1548 | <dt>EV_USE_SELECT</dt> |
|
|
1549 | <dd> |
|
|
1550 | <p>If undefined or defined to be <code>1</code>, libev will compile in support for the |
|
|
1551 | <code>select</code>(2) backend. No attempt at autodetection will be done: if no |
|
|
1552 | other method takes over, select will be it. Otherwise the select backend |
|
|
1553 | will not be compiled in.</p> |
|
|
1554 | </dd> |
|
|
1555 | <dt>EV_SELECT_USE_FD_SET</dt> |
|
|
1556 | <dd> |
|
|
1557 | <p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code> |
|
|
1558 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1559 | <code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on |
|
|
1560 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1561 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1562 | allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might |
|
|
1563 | influence the size of the <code>fd_set</code> used.</p> |
|
|
1564 | </dd> |
|
|
1565 | <dt>EV_SELECT_IS_WINSOCKET</dt> |
|
|
1566 | <dd> |
|
|
1567 | <p>When defined to <code>1</code>, the select backend will assume that |
|
|
1568 | select/socket/connect etc. don't understand file descriptors but |
|
|
1569 | wants osf handles on win32 (this is the case when the select to |
|
|
1570 | be used is the winsock select). This means that it will call |
|
|
1571 | <code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise, |
|
|
1572 | it is assumed that all these functions actually work on fds, even |
|
|
1573 | on win32. Should not be defined on non-win32 platforms.</p> |
|
|
1574 | </dd> |
|
|
1575 | <dt>EV_USE_POLL</dt> |
|
|
1576 | <dd> |
|
|
1577 | <p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2) |
|
|
1578 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1579 | takes precedence over select.</p> |
|
|
1580 | </dd> |
|
|
1581 | <dt>EV_USE_EPOLL</dt> |
|
|
1582 | <dd> |
|
|
1583 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux |
|
|
1584 | <code>epoll</code>(7) backend. Its availability will be detected at runtime, |
|
|
1585 | otherwise another method will be used as fallback. This is the |
|
|
1586 | preferred backend for GNU/Linux systems.</p> |
|
|
1587 | </dd> |
|
|
1588 | <dt>EV_USE_KQUEUE</dt> |
|
|
1589 | <dd> |
|
|
1590 | <p>If defined to be <code>1</code>, libev will compile in support for the BSD style |
|
|
1591 | <code>kqueue</code>(2) backend. Its actual availability will be detected at runtime, |
|
|
1592 | otherwise another method will be used as fallback. This is the preferred |
|
|
1593 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
1594 | supports some types of fds correctly (the only platform we found that |
|
|
1595 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
1596 | not be used unless explicitly requested. The best way to use it is to find |
|
|
1597 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
1598 | kqueue loop.</p> |
|
|
1599 | </dd> |
|
|
1600 | <dt>EV_USE_PORT</dt> |
|
|
1601 | <dd> |
|
|
1602 | <p>If defined to be <code>1</code>, libev will compile in support for the Solaris |
|
|
1603 | 10 port style backend. Its availability will be detected at runtime, |
|
|
1604 | otherwise another method will be used as fallback. This is the preferred |
|
|
1605 | backend for Solaris 10 systems.</p> |
|
|
1606 | </dd> |
|
|
1607 | <dt>EV_USE_DEVPOLL</dt> |
|
|
1608 | <dd> |
|
|
1609 | <p>reserved for future expansion, works like the USE symbols above.</p> |
|
|
1610 | </dd> |
|
|
1611 | <dt>EV_H</dt> |
|
|
1612 | <dd> |
|
|
1613 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
|
|
1614 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
|
|
1615 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
|
|
1616 | </dd> |
|
|
1617 | <dt>EV_CONFIG_H</dt> |
|
|
1618 | <dd> |
|
|
1619 | <p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override |
|
|
1620 | <cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to |
|
|
1621 | <code>EV_H</code>, above.</p> |
|
|
1622 | </dd> |
|
|
1623 | <dt>EV_EVENT_H</dt> |
|
|
1624 | <dd> |
|
|
1625 | <p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea |
|
|
1626 | of how the <cite>event.h</cite> header can be found.</p> |
|
|
1627 | </dd> |
|
|
1628 | <dt>EV_PROTOTYPES</dt> |
|
|
1629 | <dd> |
|
|
1630 | <p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function |
|
|
1631 | prototypes, but still define all the structs and other symbols. This is |
|
|
1632 | occasionally useful if you want to provide your own wrapper functions |
|
|
1633 | around libev functions.</p> |
|
|
1634 | </dd> |
|
|
1635 | <dt>EV_MULTIPLICITY</dt> |
|
|
1636 | <dd> |
|
|
1637 | <p>If undefined or defined to <code>1</code>, then all event-loop-specific functions |
|
|
1638 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
|
|
1639 | additional independent event loops. Otherwise there will be no support |
|
|
1640 | for multiple event loops and there is no first event loop pointer |
|
|
1641 | argument. Instead, all functions act on the single default loop.</p> |
|
|
1642 | </dd> |
|
|
1643 | <dt>EV_PERIODICS</dt> |
|
|
1644 | <dd> |
|
|
1645 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported, |
|
|
1646 | otherwise not. This saves a few kb of code.</p> |
|
|
1647 | </dd> |
|
|
1648 | <dt>EV_COMMON</dt> |
|
|
1649 | <dd> |
|
|
1650 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
|
|
1651 | this macro to a something else you can include more and other types of |
|
|
1652 | members. You have to define it each time you include one of the files, |
|
|
1653 | though, and it must be identical each time.</p> |
|
|
1654 | <p>For example, the perl EV module uses something like this:</p> |
|
|
1655 | <pre> #define EV_COMMON \ |
|
|
1656 | SV *self; /* contains this struct */ \ |
|
|
1657 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
1658 | |
|
|
1659 | </pre> |
|
|
1660 | </dd> |
|
|
1661 | <dt>EV_CB_DECLARE(type)</dt> |
|
|
1662 | <dt>EV_CB_INVOKE(watcher,revents)</dt> |
|
|
1663 | <dt>ev_set_cb(ev,cb)</dt> |
|
|
1664 | <dd> |
|
|
1665 | <p>Can be used to change the callback member declaration in each watcher, |
|
|
1666 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
1667 | definition and a statement, respectively. See the <cite>ev.v</cite> header file for |
|
|
1668 | their default definitions. One possible use for overriding these is to |
|
|
1669 | avoid the ev_loop pointer as first argument in all cases, or to use method |
|
|
1670 | calls instead of plain function calls in C++.</p> |
|
|
1671 | |
|
|
1672 | </div> |
|
|
1673 | <h2 id="EXAMPLES">EXAMPLES</h2> |
|
|
1674 | <div id="EXAMPLES_CONTENT"> |
|
|
1675 | <p>For a real-world example of a program the includes libev |
|
|
1676 | verbatim, you can have a look at the EV perl module |
|
|
1677 | (<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in |
|
|
1678 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
|
|
1679 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
|
|
1680 | will be compiled. It is pretty complex because it provides its own header |
|
|
1681 | file.</p> |
|
|
1682 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
|
|
1683 | that everybody includes and which overrides some autoconf choices:</p> |
|
|
1684 | <pre> #define EV_USE_POLL 0 |
|
|
1685 | #define EV_MULTIPLICITY 0 |
|
|
1686 | #define EV_PERIODICS 0 |
|
|
1687 | #define EV_CONFIG_H <config.h> |
|
|
1688 | |
|
|
1689 | #include "ev++.h" |
|
|
1690 | |
|
|
1691 | </pre> |
|
|
1692 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
|
|
1693 | <pre> #include "ev_cpp.h" |
|
|
1694 | #include "ev.c" |
|
|
1695 | |
|
|
1696 | </pre> |
773 | |
1697 | |
774 | </div> |
1698 | </div> |
775 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1699 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
776 | <div id="AUTHOR_CONTENT"> |
1700 | <div id="AUTHOR_CONTENT"> |
777 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1701 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
778 | |
1702 | |
779 | </div> |
1703 | </div> |
780 | </div></body> |
1704 | </div></body> |
781 | </html> |
1705 | </html> |