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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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8 | <meta name="outputfile" content="<standard output>" /> |
9 | <meta name="created" content="Mon Nov 12 09:58:24 2007" /> |
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12 | <body> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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35 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
35 | <li><a href="#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> |
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 | </ul> |
37 | </ul> |
38 | </li> |
38 | </li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
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40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
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41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
40 | <li><a href="#AUTHOR">AUTHOR</a> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
41 | </li> |
43 | </li> |
42 | </ul><hr /> |
44 | </ul><hr /> |
43 | <!-- INDEX END --> |
45 | <!-- INDEX END --> |
44 | |
46 | |
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94 | <div id="TIME_REPRESENTATION_CONTENT"> |
96 | <div id="TIME_REPRESENTATION_CONTENT"> |
95 | <p>Libev represents time as a single floating point number, representing the |
97 | <p>Libev represents time as a single floating point number, representing the |
96 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
97 | the beginning of 1970, details are complicated, don't ask). This type is |
99 | the beginning of 1970, details are complicated, don't ask). This type is |
98 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
100 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
99 | to the double type in C.</p> |
101 | to the <code>double</code> type in C, and when you need to do any calculations on |
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102 | it, you should treat it as such.</p> |
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103 | |
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104 | |
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105 | |
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106 | |
100 | |
107 | |
101 | </div> |
108 | </div> |
102 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
109 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
103 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
110 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
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111 | <p>These functions can be called anytime, even before initialising the |
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112 | library in any way.</p> |
104 | <dl> |
113 | <dl> |
105 | <dt>ev_tstamp ev_time ()</dt> |
114 | <dt>ev_tstamp ev_time ()</dt> |
106 | <dd> |
115 | <dd> |
107 | <p>Returns the current time as libev would use it.</p> |
116 | <p>Returns the current time as libev would use it. Please note that the |
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117 | <code>ev_now</code> function is usually faster and also often returns the timestamp |
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118 | you actually want to know.</p> |
108 | </dd> |
119 | </dd> |
109 | <dt>int ev_version_major ()</dt> |
120 | <dt>int ev_version_major ()</dt> |
110 | <dt>int ev_version_minor ()</dt> |
121 | <dt>int ev_version_minor ()</dt> |
111 | <dd> |
122 | <dd> |
112 | <p>You can find out the major and minor version numbers of the library |
123 | <p>You can find out the major and minor version numbers of the library |
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116 | version of the library your program was compiled against.</p> |
127 | version of the library your program was compiled against.</p> |
117 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
128 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
118 | as this indicates an incompatible change. Minor versions are usually |
129 | as this indicates an incompatible change. Minor versions are usually |
119 | compatible to older versions, so a larger minor version alone is usually |
130 | compatible to older versions, so a larger minor version alone is usually |
120 | not a problem.</p> |
131 | not a problem.</p> |
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132 | <p>Example: make sure we haven't accidentally been linked against the wrong |
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133 | version:</p> |
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134 | <pre> assert (("libev version mismatch", |
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135 | ev_version_major () == EV_VERSION_MAJOR |
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136 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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137 | |
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138 | </pre> |
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139 | </dd> |
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140 | <dt>unsigned int ev_supported_backends ()</dt> |
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141 | <dd> |
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142 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
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143 | value) compiled into this binary of libev (independent of their |
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144 | availability on the system you are running on). See <code>ev_default_loop</code> for |
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145 | a description of the set values.</p> |
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146 | <p>Example: make sure we have the epoll method, because yeah this is cool and |
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147 | a must have and can we have a torrent of it please!!!11</p> |
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148 | <pre> assert (("sorry, no epoll, no sex", |
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149 | ev_supported_backends () & EVBACKEND_EPOLL)); |
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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_recommended_backends ()</dt> |
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154 | <dd> |
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155 | <p>Return the set of all backends compiled into this binary of libev and also |
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156 | recommended for this platform. This set is often smaller than the one |
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157 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
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158 | most BSDs and will not be autodetected unless you explicitly request it |
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159 | (assuming you know what you are doing). This is the set of backends that |
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160 | libev will probe for if you specify no backends explicitly.</p> |
121 | </dd> |
161 | </dd> |
122 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
162 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
123 | <dd> |
163 | <dd> |
124 | <p>Sets the allocation function to use (the prototype is similar to the |
164 | <p>Sets the allocation function to use (the prototype is similar to the |
125 | realloc C function, the semantics are identical). It is used to allocate |
165 | realloc C function, the semantics are identical). It is used to allocate |
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127 | needs to be allocated, the library might abort or take some potentially |
167 | needs to be allocated, the library might abort or take some potentially |
128 | destructive action. The default is your system realloc function.</p> |
168 | destructive action. The default is your system realloc function.</p> |
129 | <p>You could override this function in high-availability programs to, say, |
169 | <p>You could override this function in high-availability programs to, say, |
130 | free some memory if it cannot allocate memory, to use a special allocator, |
170 | free some memory if it cannot allocate memory, to use a special allocator, |
131 | or even to sleep a while and retry until some memory is available.</p> |
171 | or even to sleep a while and retry until some memory is available.</p> |
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172 | <p>Example: replace the libev allocator with one that waits a bit and then |
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173 | retries: better than mine).</p> |
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174 | <pre> static void * |
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175 | persistent_realloc (void *ptr, long size) |
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176 | { |
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177 | for (;;) |
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178 | { |
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179 | void *newptr = realloc (ptr, size); |
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180 | |
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181 | if (newptr) |
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182 | return newptr; |
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183 | |
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184 | sleep (60); |
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185 | } |
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186 | } |
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187 | |
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188 | ... |
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189 | ev_set_allocator (persistent_realloc); |
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190 | |
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191 | </pre> |
132 | </dd> |
192 | </dd> |
133 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
193 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
134 | <dd> |
194 | <dd> |
135 | <p>Set the callback function to call on a retryable syscall error (such |
195 | <p>Set the callback function to call on a retryable syscall error (such |
136 | as failed select, poll, epoll_wait). The message is a printable string |
196 | as failed select, poll, epoll_wait). The message is a printable string |
137 | indicating the system call or subsystem causing the problem. If this |
197 | indicating the system call or subsystem causing the problem. If this |
138 | callback is set, then libev will expect it to remedy the sitution, no |
198 | callback is set, then libev will expect it to remedy the sitution, no |
139 | matter what, when it returns. That is, libev will generally retry the |
199 | matter what, when it returns. That is, libev will generally retry the |
140 | requested operation, or, if the condition doesn't go away, do bad stuff |
200 | requested operation, or, if the condition doesn't go away, do bad stuff |
141 | (such as abort).</p> |
201 | (such as abort).</p> |
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202 | <p>Example: do the same thing as libev does internally:</p> |
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203 | <pre> static void |
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204 | fatal_error (const char *msg) |
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205 | { |
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206 | perror (msg); |
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207 | abort (); |
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208 | } |
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209 | |
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210 | ... |
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211 | ev_set_syserr_cb (fatal_error); |
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212 | |
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213 | </pre> |
142 | </dd> |
214 | </dd> |
143 | </dl> |
215 | </dl> |
144 | |
216 | |
145 | </div> |
217 | </div> |
146 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
218 | <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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158 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
230 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
159 | <dd> |
231 | <dd> |
160 | <p>This will initialise the default event loop if it hasn't been initialised |
232 | <p>This will initialise the default event loop if it hasn't been initialised |
161 | yet and return it. If the default loop could not be initialised, returns |
233 | yet and return it. If the default loop could not be initialised, returns |
162 | false. If it already was initialised it simply returns it (and ignores the |
234 | false. If it already was initialised it simply returns it (and ignores the |
163 | flags).</p> |
235 | flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p> |
164 | <p>If you don't know what event loop to use, use the one returned from this |
236 | <p>If you don't know what event loop to use, use the one returned from this |
165 | function.</p> |
237 | function.</p> |
166 | <p>The flags argument can be used to specify special behaviour or specific |
238 | <p>The flags argument can be used to specify special behaviour or specific |
167 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p> |
239 | backends to use, and is usually specified as <code>0</code> (or <code>EVFLAG_AUTO</code>).</p> |
168 | <p>It supports the following flags:</p> |
240 | <p>The following flags are supported:</p> |
169 | <p> |
241 | <p> |
170 | <dl> |
242 | <dl> |
171 | <dt><code>EVFLAG_AUTO</code></dt> |
243 | <dt><code>EVFLAG_AUTO</code></dt> |
172 | <dd> |
244 | <dd> |
173 | <p>The default flags value. Use this if you have no clue (it's the right |
245 | <p>The default flags value. Use this if you have no clue (it's the right |
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180 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
252 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
181 | override the flags completely if it is found in the environment. This is |
253 | override the flags completely if it is found in the environment. This is |
182 | useful to try out specific backends to test their performance, or to work |
254 | useful to try out specific backends to test their performance, or to work |
183 | around bugs.</p> |
255 | around bugs.</p> |
184 | </dd> |
256 | </dd> |
185 | <dt><code>EVMETHOD_SELECT</code> (portable select backend)</dt> |
257 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
186 | <dt><code>EVMETHOD_POLL</code> (poll backend, available everywhere except on windows)</dt> |
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187 | <dt><code>EVMETHOD_EPOLL</code> (linux only)</dt> |
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188 | <dt><code>EVMETHOD_KQUEUE</code> (some bsds only)</dt> |
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189 | <dt><code>EVMETHOD_DEVPOLL</code> (solaris 8 only)</dt> |
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190 | <dt><code>EVMETHOD_PORT</code> (solaris 10 only)</dt> |
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191 | <dd> |
258 | <dd> |
192 | <p>If one or more of these are ored into the flags value, then only these |
259 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
193 | backends will be tried (in the reverse order as given here). If one are |
260 | libev tries to roll its own fd_set with no limits on the number of fds, |
194 | specified, any backend will do.</p> |
261 | but if that fails, expect a fairly low limit on the number of fds when |
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262 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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263 | the fastest backend for a low number of fds.</p> |
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264 | </dd> |
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265 | <dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
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266 | <dd> |
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267 | <p>And this is your standard poll(2) backend. It's more complicated than |
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268 | select, but handles sparse fds better and has no artificial limit on the |
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269 | number of fds you can use (except it will slow down considerably with a |
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270 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
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271 | </dd> |
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272 | <dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt> |
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273 | <dd> |
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274 | <p>For few fds, this backend is a bit little slower than poll and select, |
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275 | but it scales phenomenally better. While poll and select usually scale like |
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276 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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277 | either O(1) or O(active_fds).</p> |
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278 | <p>While stopping and starting an I/O watcher in the same iteration will |
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279 | result in some caching, there is still a syscall per such incident |
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280 | (because the fd could point to a different file description now), so its |
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281 | best to avoid that. Also, dup()ed file descriptors might not work very |
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282 | well if you register events for both fds.</p> |
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283 | <p>Please note that epoll sometimes generates spurious notifications, so you |
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284 | need to use non-blocking I/O or other means to avoid blocking when no data |
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285 | (or space) is available.</p> |
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286 | </dd> |
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287 | <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> |
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288 | <dd> |
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289 | <p>Kqueue deserves special mention, as at the time of this writing, it |
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290 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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291 | anything but sockets and pipes, except on Darwin, where of course its |
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292 | completely useless). For this reason its not being "autodetected" |
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293 | unless you explicitly specify it explicitly in the flags (i.e. using |
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294 | <code>EVBACKEND_KQUEUE</code>).</p> |
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295 | <p>It scales in the same way as the epoll backend, but the interface to the |
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296 | kernel is more efficient (which says nothing about its actual speed, of |
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297 | course). While starting and stopping an I/O watcher does not cause an |
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298 | extra syscall as with epoll, it still adds up to four event changes per |
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299 | incident, so its best to avoid that.</p> |
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300 | </dd> |
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301 | <dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt> |
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302 | <dd> |
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303 | <p>This is not implemented yet (and might never be).</p> |
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304 | </dd> |
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305 | <dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt> |
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306 | <dd> |
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307 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
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308 | it's really slow, but it still scales very well (O(active_fds)).</p> |
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309 | <p>Please note that solaris ports can result in a lot of spurious |
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310 | notifications, so you need to use non-blocking I/O or other means to avoid |
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311 | blocking when no data (or space) is available.</p> |
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312 | </dd> |
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313 | <dt><code>EVBACKEND_ALL</code></dt> |
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314 | <dd> |
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315 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
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316 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
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317 | <code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p> |
195 | </dd> |
318 | </dd> |
196 | </dl> |
319 | </dl> |
197 | </p> |
320 | </p> |
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321 | <p>If one or more of these are ored into the flags value, then only these |
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322 | backends will be tried (in the reverse order as given here). If none are |
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323 | specified, most compiled-in backend will be tried, usually in reverse |
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324 | order of their flag values :)</p> |
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325 | <p>The most typical usage is like this:</p> |
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326 | <pre> if (!ev_default_loop (0)) |
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327 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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328 | |
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329 | </pre> |
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330 | <p>Restrict libev to the select and poll backends, and do not allow |
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331 | environment settings to be taken into account:</p> |
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332 | <pre> ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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333 | |
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334 | </pre> |
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335 | <p>Use whatever libev has to offer, but make sure that kqueue is used if |
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336 | available (warning, breaks stuff, best use only with your own private |
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337 | event loop and only if you know the OS supports your types of fds):</p> |
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338 | <pre> ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
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339 | |
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340 | </pre> |
198 | </dd> |
341 | </dd> |
199 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
342 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
200 | <dd> |
343 | <dd> |
201 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
344 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
202 | always distinct from the default loop. Unlike the default loop, it cannot |
345 | always distinct from the default loop. Unlike the default loop, it cannot |
203 | handle signal and child watchers, and attempts to do so will be greeted by |
346 | handle signal and child watchers, and attempts to do so will be greeted by |
204 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
347 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
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348 | <p>Example: try to create a event loop that uses epoll and nothing else.</p> |
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349 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
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350 | if (!epoller) |
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351 | fatal ("no epoll found here, maybe it hides under your chair"); |
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352 | |
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353 | </pre> |
205 | </dd> |
354 | </dd> |
206 | <dt>ev_default_destroy ()</dt> |
355 | <dt>ev_default_destroy ()</dt> |
207 | <dd> |
356 | <dd> |
208 | <p>Destroys the default loop again (frees all memory and kernel state |
357 | <p>Destroys the default loop again (frees all memory and kernel state |
209 | etc.). This stops all registered event watchers (by not touching them in |
358 | etc.). This stops all registered event watchers (by not touching them in |
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218 | <dd> |
367 | <dd> |
219 | <p>This function reinitialises the kernel state for backends that have |
368 | <p>This function reinitialises the kernel state for backends that have |
220 | one. Despite the name, you can call it anytime, but it makes most sense |
369 | one. Despite the name, you can call it anytime, but it makes most sense |
221 | after forking, in either the parent or child process (or both, but that |
370 | after forking, in either the parent or child process (or both, but that |
222 | again makes little sense).</p> |
371 | again makes little sense).</p> |
223 | <p>You <i>must</i> call this function after forking if and only if you want to |
372 | <p>You <i>must</i> call this function in the child process after forking if and |
224 | use the event library in both processes. If you just fork+exec, you don't |
373 | only if you want to use the event library in both processes. If you just |
225 | have to call it.</p> |
374 | fork+exec, you don't have to call it.</p> |
226 | <p>The function itself is quite fast and it's usually not a problem to call |
375 | <p>The function itself is quite fast and it's usually not a problem to call |
227 | it just in case after a fork. To make this easy, the function will fit in |
376 | it just in case after a fork. To make this easy, the function will fit in |
228 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
377 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
229 | <pre> pthread_atfork (0, 0, ev_default_fork); |
378 | <pre> pthread_atfork (0, 0, ev_default_fork); |
230 | |
379 | |
231 | </pre> |
380 | </pre> |
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381 | <p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use |
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382 | without calling this function, so if you force one of those backends you |
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383 | do not need to care.</p> |
232 | </dd> |
384 | </dd> |
233 | <dt>ev_loop_fork (loop)</dt> |
385 | <dt>ev_loop_fork (loop)</dt> |
234 | <dd> |
386 | <dd> |
235 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
387 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
236 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
388 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
237 | after fork, and how you do this is entirely your own problem.</p> |
389 | after fork, and how you do this is entirely your own problem.</p> |
238 | </dd> |
390 | </dd> |
239 | <dt>unsigned int ev_method (loop)</dt> |
391 | <dt>unsigned int ev_backend (loop)</dt> |
240 | <dd> |
392 | <dd> |
241 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
393 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
242 | use.</p> |
394 | use.</p> |
243 | </dd> |
395 | </dd> |
244 | <dt>ev_tstamp ev_now (loop)</dt> |
396 | <dt>ev_tstamp ev_now (loop)</dt> |
245 | <dd> |
397 | <dd> |
246 | <p>Returns the current "event loop time", which is the time the event loop |
398 | <p>Returns the current "event loop time", which is the time the event loop |
247 | got events and started processing them. This timestamp does not change |
399 | received events and started processing them. This timestamp does not |
248 | as long as callbacks are being processed, and this is also the base time |
400 | change as long as callbacks are being processed, and this is also the base |
249 | used for relative timers. You can treat it as the timestamp of the event |
401 | time used for relative timers. You can treat it as the timestamp of the |
250 | occuring (or more correctly, the mainloop finding out about it).</p> |
402 | event occuring (or more correctly, libev finding out about it).</p> |
251 | </dd> |
403 | </dd> |
252 | <dt>ev_loop (loop, int flags)</dt> |
404 | <dt>ev_loop (loop, int flags)</dt> |
253 | <dd> |
405 | <dd> |
254 | <p>Finally, this is it, the event handler. This function usually is called |
406 | <p>Finally, this is it, the event handler. This function usually is called |
255 | after you initialised all your watchers and you want to start handling |
407 | after you initialised all your watchers and you want to start handling |
256 | events.</p> |
408 | events.</p> |
257 | <p>If the flags argument is specified as 0, it will not return until either |
409 | <p>If the flags argument is specified as <code>0</code>, it will not return until |
258 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
410 | either no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
|
|
411 | <p>Please note that an explicit <code>ev_unloop</code> is usually better than |
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412 | relying on all watchers to be stopped when deciding when a program has |
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413 | finished (especially in interactive programs), but having a program that |
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414 | automatically loops as long as it has to and no longer by virtue of |
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415 | relying on its watchers stopping correctly is a thing of beauty.</p> |
259 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
416 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
260 | those events and any outstanding ones, but will not block your process in |
417 | those events and any outstanding ones, but will not block your process in |
261 | case there are no events and will return after one iteration of the loop.</p> |
418 | case there are no events and will return after one iteration of the loop.</p> |
262 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
419 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
263 | neccessary) and will handle those and any outstanding ones. It will block |
420 | neccessary) and will handle those and any outstanding ones. It will block |
264 | your process until at least one new event arrives, and will return after |
421 | your process until at least one new event arrives, and will return after |
265 | one iteration of the loop.</p> |
422 | one iteration of the loop. This is useful if you are waiting for some |
266 | <p>This flags value could be used to implement alternative looping |
423 | external event in conjunction with something not expressible using other |
267 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
424 | libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is |
268 | more generic mechanism.</p> |
425 | usually a better approach for this kind of thing.</p> |
|
|
426 | <p>Here are the gory details of what <code>ev_loop</code> does:</p> |
|
|
427 | <pre> * If there are no active watchers (reference count is zero), return. |
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428 | - Queue prepare watchers and then call all outstanding watchers. |
|
|
429 | - If we have been forked, recreate the kernel state. |
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430 | - Update the kernel state with all outstanding changes. |
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431 | - Update the "event loop time". |
|
|
432 | - Calculate for how long to block. |
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433 | - Block the process, waiting for any events. |
|
|
434 | - Queue all outstanding I/O (fd) events. |
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435 | - Update the "event loop time" and do time jump handling. |
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436 | - Queue all outstanding timers. |
|
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437 | - Queue all outstanding periodics. |
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438 | - If no events are pending now, queue all idle watchers. |
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439 | - Queue all check watchers. |
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440 | - Call all queued watchers in reverse order (i.e. check watchers first). |
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441 | Signals and child watchers are implemented as I/O watchers, and will |
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442 | be handled here by queueing them when their watcher gets executed. |
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443 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
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|
444 | were used, return, otherwise continue with step *. |
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445 | |
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446 | </pre> |
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|
447 | <p>Example: queue some jobs and then loop until no events are outsanding |
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448 | anymore.</p> |
|
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449 | <pre> ... queue jobs here, make sure they register event watchers as long |
|
|
450 | ... as they still have work to do (even an idle watcher will do..) |
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451 | ev_loop (my_loop, 0); |
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452 | ... jobs done. yeah! |
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453 | |
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454 | </pre> |
269 | </dd> |
455 | </dd> |
270 | <dt>ev_unloop (loop, how)</dt> |
456 | <dt>ev_unloop (loop, how)</dt> |
271 | <dd> |
457 | <dd> |
272 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
458 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
273 | has processed all outstanding events). The <code>how</code> argument must be either |
459 | has processed all outstanding events). The <code>how</code> argument must be either |
274 | <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> call return, or |
460 | <code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or |
275 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
461 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
276 | </dd> |
462 | </dd> |
277 | <dt>ev_ref (loop)</dt> |
463 | <dt>ev_ref (loop)</dt> |
278 | <dt>ev_unref (loop)</dt> |
464 | <dt>ev_unref (loop)</dt> |
279 | <dd> |
465 | <dd> |
… | |
… | |
285 | example, libev itself uses this for its internal signal pipe: It is not |
471 | example, libev itself uses this for its internal signal pipe: It is not |
286 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
472 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
287 | no event watchers registered by it are active. It is also an excellent |
473 | no event watchers registered by it are active. It is also an excellent |
288 | way to do this for generic recurring timers or from within third-party |
474 | way to do this for generic recurring timers or from within third-party |
289 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
475 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
|
|
476 | <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> |
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477 | running when nothing else is active.</p> |
|
|
478 | <pre> struct dv_signal exitsig; |
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479 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
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480 | ev_signal_start (myloop, &exitsig); |
|
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481 | evf_unref (myloop); |
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482 | |
|
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483 | </pre> |
|
|
484 | <p>Example: for some weird reason, unregister the above signal handler again.</p> |
|
|
485 | <pre> ev_ref (myloop); |
|
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486 | ev_signal_stop (myloop, &exitsig); |
|
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487 | |
|
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488 | </pre> |
290 | </dd> |
489 | </dd> |
291 | </dl> |
490 | </dl> |
292 | |
491 | |
293 | </div> |
492 | </div> |
294 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
493 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
… | |
… | |
326 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
525 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
327 | *)</code>), and you can stop watching for events at any time by calling the |
526 | *)</code>), and you can stop watching for events at any time by calling the |
328 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
527 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
329 | <p>As long as your watcher is active (has been started but not stopped) you |
528 | <p>As long as your watcher is active (has been started but not stopped) you |
330 | must not touch the values stored in it. Most specifically you must never |
529 | must not touch the values stored in it. Most specifically you must never |
331 | reinitialise it or call its set method.</p> |
530 | reinitialise it or call its set macro.</p> |
332 | <p>You can check whether an event is active by calling the <code>ev_is_active |
531 | <p>You can check whether an event is active by calling the <code>ev_is_active |
333 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
532 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
334 | callback for it has not been called yet) you can use the <code>ev_is_pending |
533 | callback for it has not been called yet) you can use the <code>ev_is_pending |
335 | (watcher *)</code> macro.</p> |
534 | (watcher *)</code> macro.</p> |
336 | <p>Each and every callback receives the event loop pointer as first, the |
535 | <p>Each and every callback receives the event loop pointer as first, the |
… | |
… | |
430 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
629 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
431 | <div id="WATCHER_TYPES_CONTENT"> |
630 | <div id="WATCHER_TYPES_CONTENT"> |
432 | <p>This section describes each watcher in detail, but will not repeat |
631 | <p>This section describes each watcher in detail, but will not repeat |
433 | information given in the last section.</p> |
632 | information given in the last section.</p> |
434 | |
633 | |
|
|
634 | |
|
|
635 | |
|
|
636 | |
|
|
637 | |
435 | </div> |
638 | </div> |
436 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
639 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
437 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
640 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
438 | <p>I/O watchers check whether a file descriptor is readable or writable |
641 | <p>I/O watchers check whether a file descriptor is readable or writable |
439 | in each iteration of the event loop (This behaviour is called |
642 | in each iteration of the event loop (This behaviour is called |
440 | level-triggering because you keep receiving events as long as the |
643 | level-triggering because you keep receiving events as long as the |
441 | condition persists. Remember you can stop the watcher if you don't want to |
644 | condition persists. Remember you can stop the watcher if you don't want to |
442 | act on the event and neither want to receive future events).</p> |
645 | act on the event and neither want to receive future events).</p> |
443 | <p>In general you can register as many read and/or write event watchers oer |
646 | <p>In general you can register as many read and/or write event watchers per |
444 | fd as you want (as long as you don't confuse yourself). Setting all file |
647 | fd as you want (as long as you don't confuse yourself). Setting all file |
445 | descriptors to non-blocking mode is also usually a good idea (but not |
648 | descriptors to non-blocking mode is also usually a good idea (but not |
446 | required if you know what you are doing).</p> |
649 | required if you know what you are doing).</p> |
447 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
650 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
448 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
651 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
449 | descriptors correctly if you register interest in two or more fds pointing |
652 | descriptors correctly if you register interest in two or more fds pointing |
450 | to the same file/socket etc. description.</p> |
653 | to the same underlying file/socket etc. description (that is, they share |
|
|
654 | the same underlying "file open").</p> |
451 | <p>If you must do this, then force the use of a known-to-be-good backend |
655 | <p>If you must do this, then force the use of a known-to-be-good backend |
452 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
656 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
453 | EVMETHOD_POLL).</p> |
657 | <code>EVBACKEND_POLL</code>).</p> |
454 | <dl> |
658 | <dl> |
455 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
659 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
456 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
660 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
457 | <dd> |
661 | <dd> |
458 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
662 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
459 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
663 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
460 | EV_WRITE</code> to receive the given events.</p> |
664 | EV_WRITE</code> to receive the given events.</p> |
|
|
665 | <p>Please note that most of the more scalable backend mechanisms (for example |
|
|
666 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
667 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
668 | treat callback invocation as hint only), or retest separately with a safe |
|
|
669 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
670 | <code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this |
|
|
671 | problem. Also note that it is quite easy to have your callback invoked |
|
|
672 | when the readyness condition is no longer valid even when employing |
|
|
673 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
674 | I/O unconditionally.</p> |
461 | </dd> |
675 | </dd> |
462 | </dl> |
676 | </dl> |
|
|
677 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
|
|
678 | readable, but only once. Since it is likely line-buffered, you could |
|
|
679 | attempt to read a whole line in the callback:</p> |
|
|
680 | <pre> static void |
|
|
681 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
682 | { |
|
|
683 | ev_io_stop (loop, w); |
|
|
684 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
685 | } |
|
|
686 | |
|
|
687 | ... |
|
|
688 | struct ev_loop *loop = ev_default_init (0); |
|
|
689 | struct ev_io stdin_readable; |
|
|
690 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
691 | ev_io_start (loop, &stdin_readable); |
|
|
692 | ev_loop (loop, 0); |
|
|
693 | |
|
|
694 | |
|
|
695 | |
|
|
696 | |
|
|
697 | </pre> |
463 | |
698 | |
464 | </div> |
699 | </div> |
465 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
700 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
466 | <div id="code_ev_timer_code_relative_and_opti-2"> |
701 | <div id="code_ev_timer_code_relative_and_opti-2"> |
467 | <p>Timer watchers are simple relative timers that generate an event after a |
702 | <p>Timer watchers are simple relative timers that generate an event after a |
468 | given time, and optionally repeating in regular intervals after that.</p> |
703 | given time, and optionally repeating in regular intervals after that.</p> |
469 | <p>The timers are based on real time, that is, if you register an event that |
704 | <p>The timers are based on real time, that is, if you register an event that |
470 | times out after an hour and youreset your system clock to last years |
705 | times out after an hour and you reset your system clock to last years |
471 | time, it will still time out after (roughly) and hour. "Roughly" because |
706 | time, it will still time out after (roughly) and hour. "Roughly" because |
472 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
707 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
473 | monotonic clock option helps a lot here).</p> |
708 | monotonic clock option helps a lot here).</p> |
474 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
709 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
475 | time. This is usually the right thing as this timestamp refers to the time |
710 | time. This is usually the right thing as this timestamp refers to the time |
476 | of the event triggering whatever timeout you are modifying/starting. If |
711 | of the event triggering whatever timeout you are modifying/starting. If |
477 | you suspect event processing to be delayed and you *need* to base the timeout |
712 | you suspect event processing to be delayed and you <i>need</i> to base the timeout |
478 | ion the current time, use something like this to adjust for this:</p> |
713 | on the current time, use something like this to adjust for this:</p> |
479 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
714 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
480 | |
715 | |
481 | </pre> |
716 | </pre> |
|
|
717 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
718 | but if multiple timers become ready during the same loop iteration then |
|
|
719 | order of execution is undefined.</p> |
482 | <dl> |
720 | <dl> |
483 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
721 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
484 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
722 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
485 | <dd> |
723 | <dd> |
486 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
724 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
488 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
726 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
489 | later, again, and again, until stopped manually.</p> |
727 | later, again, and again, until stopped manually.</p> |
490 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
728 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
491 | configure a timer to trigger every 10 seconds, then it will trigger at |
729 | configure a timer to trigger every 10 seconds, then it will trigger at |
492 | exactly 10 second intervals. If, however, your program cannot keep up with |
730 | exactly 10 second intervals. If, however, your program cannot keep up with |
493 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
731 | the timer (because it takes longer than those 10 seconds to do stuff) the |
494 | timer will not fire more than once per event loop iteration.</p> |
732 | timer will not fire more than once per event loop iteration.</p> |
495 | </dd> |
733 | </dd> |
496 | <dt>ev_timer_again (loop)</dt> |
734 | <dt>ev_timer_again (loop)</dt> |
497 | <dd> |
735 | <dd> |
498 | <p>This will act as if the timer timed out and restart it again if it is |
736 | <p>This will act as if the timer timed out and restart it again if it is |
… | |
… | |
508 | time you successfully read or write some data. If you go into an idle |
746 | time you successfully read or write some data. If you go into an idle |
509 | state where you do not expect data to travel on the socket, you can stop |
747 | state where you do not expect data to travel on the socket, you can stop |
510 | the timer, and again will automatically restart it if need be.</p> |
748 | the timer, and again will automatically restart it if need be.</p> |
511 | </dd> |
749 | </dd> |
512 | </dl> |
750 | </dl> |
|
|
751 | <p>Example: create a timer that fires after 60 seconds.</p> |
|
|
752 | <pre> static void |
|
|
753 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
754 | { |
|
|
755 | .. one minute over, w is actually stopped right here |
|
|
756 | } |
|
|
757 | |
|
|
758 | struct ev_timer mytimer; |
|
|
759 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
760 | ev_timer_start (loop, &mytimer); |
|
|
761 | |
|
|
762 | </pre> |
|
|
763 | <p>Example: create a timeout timer that times out after 10 seconds of |
|
|
764 | inactivity.</p> |
|
|
765 | <pre> static void |
|
|
766 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
767 | { |
|
|
768 | .. ten seconds without any activity |
|
|
769 | } |
|
|
770 | |
|
|
771 | struct ev_timer mytimer; |
|
|
772 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
773 | ev_timer_again (&mytimer); /* start timer */ |
|
|
774 | ev_loop (loop, 0); |
|
|
775 | |
|
|
776 | // and in some piece of code that gets executed on any "activity": |
|
|
777 | // reset the timeout to start ticking again at 10 seconds |
|
|
778 | ev_timer_again (&mytimer); |
|
|
779 | |
|
|
780 | |
|
|
781 | |
|
|
782 | |
|
|
783 | </pre> |
513 | |
784 | |
514 | </div> |
785 | </div> |
515 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
786 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
516 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
787 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
517 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
788 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
… | |
… | |
524 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
795 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
525 | roughly 10 seconds later and of course not if you reset your system time |
796 | roughly 10 seconds later and of course not if you reset your system time |
526 | again).</p> |
797 | again).</p> |
527 | <p>They can also be used to implement vastly more complex timers, such as |
798 | <p>They can also be used to implement vastly more complex timers, such as |
528 | triggering an event on eahc midnight, local time.</p> |
799 | triggering an event on eahc midnight, local time.</p> |
|
|
800 | <p>As with timers, the callback is guarenteed to be invoked only when the |
|
|
801 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
|
|
802 | during the same loop iteration then order of execution is undefined.</p> |
529 | <dl> |
803 | <dl> |
530 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
804 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
531 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
805 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
532 | <dd> |
806 | <dd> |
533 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
807 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
534 | operation, and we will explain them from simplest to complex:</p> |
808 | operation, and we will explain them from simplest to complex:</p> |
535 | |
|
|
536 | |
|
|
537 | |
|
|
538 | |
|
|
539 | <p> |
809 | <p> |
540 | <dl> |
810 | <dl> |
541 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
811 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
542 | <dd> |
812 | <dd> |
543 | <p>In this configuration the watcher triggers an event at the wallclock time |
813 | <p>In this configuration the watcher triggers an event at the wallclock time |
… | |
… | |
567 | <dd> |
837 | <dd> |
568 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
838 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
569 | ignored. Instead, each time the periodic watcher gets scheduled, the |
839 | ignored. Instead, each time the periodic watcher gets scheduled, the |
570 | reschedule callback will be called with the watcher as first, and the |
840 | reschedule callback will be called with the watcher as first, and the |
571 | current time as second argument.</p> |
841 | current time as second argument.</p> |
572 | <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other |
842 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
573 | periodic watcher, ever, or make any event loop modifications</i>. If you need |
843 | ever, or make any event loop modifications</i>. If you need to stop it, |
574 | to stop it, return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards.</p> |
844 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
575 | <p>Also, <i>this callback must always return a time that is later than the |
845 | starting a prepare watcher).</p> |
576 | passed <code>now</code> value</i>. Not even <code>now</code> itself will be ok.</p> |
|
|
577 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
846 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
578 | ev_tstamp now)</code>, e.g.:</p> |
847 | ev_tstamp now)</code>, e.g.:</p> |
579 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
848 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
580 | { |
849 | { |
581 | return now + 60.; |
850 | return now + 60.; |
… | |
… | |
584 | </pre> |
853 | </pre> |
585 | <p>It must return the next time to trigger, based on the passed time value |
854 | <p>It must return the next time to trigger, based on the passed time value |
586 | (that is, the lowest time value larger than to the second argument). It |
855 | (that is, the lowest time value larger than to the second argument). It |
587 | will usually be called just before the callback will be triggered, but |
856 | will usually be called just before the callback will be triggered, but |
588 | might be called at other times, too.</p> |
857 | might be called at other times, too.</p> |
|
|
858 | <p>NOTE: <i>This callback must always return a time that is later than the |
|
|
859 | passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p> |
589 | <p>This can be used to create very complex timers, such as a timer that |
860 | <p>This can be used to create very complex timers, such as a timer that |
590 | triggers on each midnight, local time. To do this, you would calculate the |
861 | triggers on each midnight, local time. To do this, you would calculate the |
591 | next midnight after <code>now</code> and return the timestamp value for this. How you do this |
862 | next midnight after <code>now</code> and return the timestamp value for this. How |
592 | is, again, up to you (but it is not trivial).</p> |
863 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
864 | reason I omitted it as an example).</p> |
593 | </dd> |
865 | </dd> |
594 | </dl> |
866 | </dl> |
595 | </p> |
867 | </p> |
596 | </dd> |
868 | </dd> |
597 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
869 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
… | |
… | |
600 | when you changed some parameters or the reschedule callback would return |
872 | when you changed some parameters or the reschedule callback would return |
601 | a different time than the last time it was called (e.g. in a crond like |
873 | a different time than the last time it was called (e.g. in a crond like |
602 | program when the crontabs have changed).</p> |
874 | program when the crontabs have changed).</p> |
603 | </dd> |
875 | </dd> |
604 | </dl> |
876 | </dl> |
|
|
877 | <p>Example: call a callback every hour, or, more precisely, whenever the |
|
|
878 | system clock is divisible by 3600. The callback invocation times have |
|
|
879 | potentially a lot of jittering, but good long-term stability.</p> |
|
|
880 | <pre> static void |
|
|
881 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
882 | { |
|
|
883 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
884 | } |
|
|
885 | |
|
|
886 | struct ev_periodic hourly_tick; |
|
|
887 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
888 | ev_periodic_start (loop, &hourly_tick); |
|
|
889 | |
|
|
890 | </pre> |
|
|
891 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
|
|
892 | <pre> #include <math.h> |
|
|
893 | |
|
|
894 | static ev_tstamp |
|
|
895 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
896 | { |
|
|
897 | return fmod (now, 3600.) + 3600.; |
|
|
898 | } |
|
|
899 | |
|
|
900 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
901 | |
|
|
902 | </pre> |
|
|
903 | <p>Example: call a callback every hour, starting now:</p> |
|
|
904 | <pre> struct ev_periodic hourly_tick; |
|
|
905 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
906 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
907 | ev_periodic_start (loop, &hourly_tick); |
|
|
908 | |
|
|
909 | |
|
|
910 | |
|
|
911 | |
|
|
912 | </pre> |
605 | |
913 | |
606 | </div> |
914 | </div> |
607 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
915 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
608 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
916 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
609 | <p>Signal watchers will trigger an event when the process receives a specific |
917 | <p>Signal watchers will trigger an event when the process receives a specific |
… | |
… | |
640 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
948 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
641 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
949 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
642 | process causing the status change.</p> |
950 | process causing the status change.</p> |
643 | </dd> |
951 | </dd> |
644 | </dl> |
952 | </dl> |
|
|
953 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
|
|
954 | <pre> static void |
|
|
955 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
956 | { |
|
|
957 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
958 | } |
|
|
959 | |
|
|
960 | struct ev_signal signal_watcher; |
|
|
961 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
962 | ev_signal_start (loop, &sigint_cb); |
|
|
963 | |
|
|
964 | |
|
|
965 | |
|
|
966 | |
|
|
967 | </pre> |
645 | |
968 | |
646 | </div> |
969 | </div> |
647 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
970 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
648 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
971 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
649 | <p>Idle watchers trigger events when there are no other events are pending |
972 | <p>Idle watchers trigger events when there are no other events are pending |
… | |
… | |
665 | <p>Initialises and configures the idle watcher - it has no parameters of any |
988 | <p>Initialises and configures the idle watcher - it has no parameters of any |
666 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
989 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
667 | believe me.</p> |
990 | believe me.</p> |
668 | </dd> |
991 | </dd> |
669 | </dl> |
992 | </dl> |
|
|
993 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
|
|
994 | callback, free it. Alos, use no error checking, as usual.</p> |
|
|
995 | <pre> static void |
|
|
996 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
997 | { |
|
|
998 | free (w); |
|
|
999 | // now do something you wanted to do when the program has |
|
|
1000 | // no longer asnything immediate to do. |
|
|
1001 | } |
|
|
1002 | |
|
|
1003 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1004 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1005 | ev_idle_start (loop, idle_cb); |
|
|
1006 | |
|
|
1007 | |
|
|
1008 | |
|
|
1009 | |
|
|
1010 | </pre> |
670 | |
1011 | |
671 | </div> |
1012 | </div> |
672 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
1013 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
673 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1014 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
674 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1015 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
675 | Prepare watchers get invoked before the process blocks and check watchers |
1016 | prepare watchers get invoked before the process blocks and check watchers |
676 | afterwards.</p> |
1017 | afterwards.</p> |
677 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
1018 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
678 | could be used, for example, to track variable changes, implement your own |
1019 | could be used, for example, to track variable changes, implement your own |
679 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
1020 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
680 | <p>This is done by examining in each prepare call which file descriptors need |
1021 | <p>This is done by examining in each prepare call which file descriptors need |
681 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1022 | to be watched by the other library, registering <code>ev_io</code> watchers for |
682 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1023 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
683 | provide just this functionality). Then, in the check watcher you check for |
1024 | provide just this functionality). Then, in the check watcher you check for |
684 | any events that occured (by checking the pending status of all watchers |
1025 | any events that occured (by checking the pending status of all watchers |
685 | and stopping them) and call back into the library. The I/O and timer |
1026 | and stopping them) and call back into the library. The I/O and timer |
686 | callbacks will never actually be called (but must be valid neverthelles, |
1027 | callbacks will never actually be called (but must be valid nevertheless, |
687 | because you never know, you know?).</p> |
1028 | because you never know, you know?).</p> |
688 | <p>As another example, the Perl Coro module uses these hooks to integrate |
1029 | <p>As another example, the Perl Coro module uses these hooks to integrate |
689 | coroutines into libev programs, by yielding to other active coroutines |
1030 | coroutines into libev programs, by yielding to other active coroutines |
690 | during each prepare and only letting the process block if no coroutines |
1031 | during each prepare and only letting the process block if no coroutines |
691 | are ready to run (its actually more complicated, it only runs coroutines |
1032 | are ready to run (it's actually more complicated: it only runs coroutines |
692 | with priority higher than the event loop and one lower priority once, |
1033 | with priority higher than or equal to the event loop and one coroutine |
693 | using idle watchers to keep the event loop from blocking if lower-priority |
1034 | of lower priority, but only once, using idle watchers to keep the event |
694 | coroutines exist, thus mapping low-priority coroutines to idle/background |
1035 | loop from blocking if lower-priority coroutines are active, thus mapping |
695 | tasks).</p> |
1036 | low-priority coroutines to idle/background tasks).</p> |
696 | <dl> |
1037 | <dl> |
697 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1038 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
698 | <dt>ev_check_init (ev_check *, callback)</dt> |
1039 | <dt>ev_check_init (ev_check *, callback)</dt> |
699 | <dd> |
1040 | <dd> |
700 | <p>Initialises and configures the prepare or check watcher - they have no |
1041 | <p>Initialises and configures the prepare or check watcher - they have no |
701 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1042 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
702 | macros, but using them is utterly, utterly and completely pointless.</p> |
1043 | macros, but using them is utterly, utterly and completely pointless.</p> |
703 | </dd> |
1044 | </dd> |
704 | </dl> |
1045 | </dl> |
|
|
1046 | <p>Example: *TODO*.</p> |
|
|
1047 | |
|
|
1048 | |
|
|
1049 | |
|
|
1050 | |
705 | |
1051 | |
706 | </div> |
1052 | </div> |
707 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1053 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
708 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1054 | <div id="OTHER_FUNCTIONS_CONTENT"> |
709 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1055 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
… | |
… | |
711 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1057 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
712 | <dd> |
1058 | <dd> |
713 | <p>This function combines a simple timer and an I/O watcher, calls your |
1059 | <p>This function combines a simple timer and an I/O watcher, calls your |
714 | callback on whichever event happens first and automatically stop both |
1060 | callback on whichever event happens first and automatically stop both |
715 | watchers. This is useful if you want to wait for a single event on an fd |
1061 | watchers. This is useful if you want to wait for a single event on an fd |
716 | or timeout without havign to allocate/configure/start/stop/free one or |
1062 | or timeout without having to allocate/configure/start/stop/free one or |
717 | more watchers yourself.</p> |
1063 | more watchers yourself.</p> |
718 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events |
1064 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events |
719 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
1065 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
720 | <code>events</code> set will be craeted and started.</p> |
1066 | <code>events</code> set will be craeted and started.</p> |
721 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
1067 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
722 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
1068 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
723 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
1069 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
724 | dubious value.</p> |
1070 | dubious value.</p> |
725 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets |
1071 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets |
726 | passed an events set like normal event callbacks (with a combination of |
1072 | passed an <code>revents</code> set like normal event callbacks (a combination of |
727 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
1073 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
728 | value passed to <code>ev_once</code>:</p> |
1074 | value passed to <code>ev_once</code>:</p> |
729 | <pre> static void stdin_ready (int revents, void *arg) |
1075 | <pre> static void stdin_ready (int revents, void *arg) |
730 | { |
1076 | { |
731 | if (revents & EV_TIMEOUT) |
1077 | if (revents & EV_TIMEOUT) |
… | |
… | |
753 | <dd> |
1099 | <dd> |
754 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
1100 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
755 | </dd> |
1101 | </dd> |
756 | </dl> |
1102 | </dl> |
757 | |
1103 | |
|
|
1104 | |
|
|
1105 | |
|
|
1106 | |
|
|
1107 | |
|
|
1108 | </div> |
|
|
1109 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
1110 | <div id="LIBEVENT_EMULATION_CONTENT"> |
|
|
1111 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
1112 | emulate the internals of libevent, so here are some usage hints:</p> |
|
|
1113 | <dl> |
|
|
1114 | <dt>* Use it by including <event.h>, as usual.</dt> |
|
|
1115 | <dt>* The following members are fully supported: ev_base, ev_callback, |
|
|
1116 | ev_arg, ev_fd, ev_res, ev_events.</dt> |
|
|
1117 | <dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
1118 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
1119 | it a private API).</dt> |
|
|
1120 | <dt>* Priorities are not currently supported. Initialising priorities |
|
|
1121 | will fail and all watchers will have the same priority, even though there |
|
|
1122 | is an ev_pri field.</dt> |
|
|
1123 | <dt>* Other members are not supported.</dt> |
|
|
1124 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
|
|
1125 | to use the libev header file and library.</dt> |
|
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1126 | </dl> |
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1127 | |
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1128 | </div> |
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1129 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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1130 | <div id="C_SUPPORT_CONTENT"> |
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1131 | <p>TBD.</p> |
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1132 | |
758 | </div> |
1133 | </div> |
759 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1134 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
760 | <div id="AUTHOR_CONTENT"> |
1135 | <div id="AUTHOR_CONTENT"> |
761 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1136 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
762 | |
1137 | |