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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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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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106 | <p>These functions can be called anytime, even before initialising the |
106 | <p>These functions can be called anytime, even before initialising the |
107 | library in any way.</p> |
107 | library in any way.</p> |
108 | <dl> |
108 | <dl> |
109 | <dt>ev_tstamp ev_time ()</dt> |
109 | <dt>ev_tstamp ev_time ()</dt> |
110 | <dd> |
110 | <dd> |
111 | <p>Returns the current time as libev would use it.</p> |
111 | <p>Returns the current time as libev would use it. Please note that the |
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112 | <code>ev_now</code> function is usually faster and also often returns the timestamp |
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113 | you actually want to know.</p> |
112 | </dd> |
114 | </dd> |
113 | <dt>int ev_version_major ()</dt> |
115 | <dt>int ev_version_major ()</dt> |
114 | <dt>int ev_version_minor ()</dt> |
116 | <dt>int ev_version_minor ()</dt> |
115 | <dd> |
117 | <dd> |
116 | <p>You can find out the major and minor version numbers of the library |
118 | <p>You can find out the major and minor version numbers of the library |
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120 | version of the library your program was compiled against.</p> |
122 | 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, |
123 | <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 |
124 | as this indicates an incompatible change. Minor versions are usually |
123 | compatible to older versions, so a larger minor version alone is usually |
125 | compatible to older versions, so a larger minor version alone is usually |
124 | not a problem.</p> |
126 | not a problem.</p> |
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127 | </dd> |
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128 | <dt>unsigned int ev_supported_backends ()</dt> |
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129 | <dd> |
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130 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
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131 | value) compiled into this binary of libev (independent of their |
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132 | availability on the system you are running on). See <code>ev_default_loop</code> for |
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133 | a description of the set values.</p> |
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134 | </dd> |
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135 | <dt>unsigned int ev_recommended_backends ()</dt> |
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136 | <dd> |
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137 | <p>Return the set of all backends compiled into this binary of libev and also |
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138 | recommended for this platform. This set is often smaller than the one |
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139 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
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140 | most BSDs and will not be autodetected unless you explicitly request it |
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141 | (assuming you know what you are doing). This is the set of backends that |
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142 | <code>EVFLAG_AUTO</code> will probe for.</p> |
125 | </dd> |
143 | </dd> |
126 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
144 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
127 | <dd> |
145 | <dd> |
128 | <p>Sets the allocation function to use (the prototype is similar to the |
146 | <p>Sets the allocation function to use (the prototype is similar to the |
129 | realloc C function, the semantics are identical). It is used to allocate |
147 | realloc C function, the semantics are identical). It is used to allocate |
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162 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
180 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
163 | <dd> |
181 | <dd> |
164 | <p>This will initialise the default event loop if it hasn't been initialised |
182 | <p>This will initialise the default event loop if it hasn't been initialised |
165 | yet and return it. If the default loop could not be initialised, returns |
183 | yet and return it. If the default loop could not be initialised, returns |
166 | false. If it already was initialised it simply returns it (and ignores the |
184 | false. If it already was initialised it simply returns it (and ignores the |
167 | flags).</p> |
185 | 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 |
186 | <p>If you don't know what event loop to use, use the one returned from this |
169 | function.</p> |
187 | function.</p> |
170 | <p>The flags argument can be used to specify special behaviour or specific |
188 | <p>The flags argument can be used to specify special behaviour or specific |
171 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p> |
189 | backends to use, and is usually specified as <code>0</code> (or EVFLAG_AUTO).</p> |
172 | <p>It supports the following flags:</p> |
190 | <p>It supports the following flags:</p> |
173 | <p> |
191 | <p> |
174 | <dl> |
192 | <dl> |
175 | <dt><code>EVFLAG_AUTO</code></dt> |
193 | <dt><code>EVFLAG_AUTO</code></dt> |
176 | <dd> |
194 | <dd> |
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184 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
202 | <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 |
203 | 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 |
204 | useful to try out specific backends to test their performance, or to work |
187 | around bugs.</p> |
205 | around bugs.</p> |
188 | </dd> |
206 | </dd> |
189 | <dt><code>EVMETHOD_SELECT</code> (portable select backend)</dt> |
207 | <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> |
208 | <dd> |
191 | <dt><code>EVMETHOD_EPOLL</code> (linux only)</dt> |
209 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
192 | <dt><code>EVMETHOD_KQUEUE</code> (some bsds only)</dt> |
210 | 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> |
211 | 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> |
212 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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213 | the fastest backend for a low number of fds.</p> |
195 | <dd> |
214 | </dd> |
196 | <p>If one or more of these are ored into the flags value, then only these |
215 | <dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
197 | backends will be tried (in the reverse order as given here). If one are |
216 | <dd> |
198 | specified, any backend will do.</p> |
217 | <p>And this is your standard poll(2) backend. It's more complicated than |
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218 | select, but handles sparse fds better and has no artificial limit on the |
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219 | number of fds you can use (except it will slow down considerably with a |
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220 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
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221 | </dd> |
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222 | <dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt> |
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223 | <dd> |
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224 | <p>For few fds, this backend is a bit little slower than poll and select, |
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225 | but it scales phenomenally better. While poll and select usually scale like |
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226 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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227 | either O(1) or O(active_fds).</p> |
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228 | <p>While stopping and starting an I/O watcher in the same iteration will |
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229 | result in some caching, there is still a syscall per such incident |
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230 | (because the fd could point to a different file description now), so its |
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231 | best to avoid that. Also, dup()ed file descriptors might not work very |
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232 | well if you register events for both fds.</p> |
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233 | <p>Please note that epoll sometimes generates spurious notifications, so you |
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234 | need to use non-blocking I/O or other means to avoid blocking when no data |
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235 | (or space) is available.</p> |
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236 | </dd> |
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237 | <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> |
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238 | <dd> |
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239 | <p>Kqueue deserves special mention, as at the time of this writing, it |
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240 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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241 | anything but sockets and pipes, except on Darwin, where of course its |
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242 | completely useless). For this reason its not being "autodetected" unless |
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243 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).</p> |
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244 | <p>It scales in the same way as the epoll backend, but the interface to the |
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245 | kernel is more efficient (which says nothing about its actual speed, of |
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246 | course). While starting and stopping an I/O watcher does not cause an |
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247 | extra syscall as with epoll, it still adds up to four event changes per |
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248 | incident, so its best to avoid that.</p> |
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249 | </dd> |
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250 | <dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt> |
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251 | <dd> |
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252 | <p>This is not implemented yet (and might never be).</p> |
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253 | </dd> |
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254 | <dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt> |
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255 | <dd> |
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256 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
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257 | it's really slow, but it still scales very well (O(active_fds)).</p> |
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258 | <p>Please note that solaris ports can result in a lot of spurious |
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259 | notifications, so you need to use non-blocking I/O or other means to avoid |
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260 | blocking when no data (or space) is available.</p> |
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261 | </dd> |
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262 | <dt><code>EVBACKEND_ALL</code></dt> |
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263 | <dd> |
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264 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
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265 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
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266 | <code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p> |
199 | </dd> |
267 | </dd> |
200 | </dl> |
268 | </dl> |
201 | </p> |
269 | </p> |
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270 | <p>If one or more of these are ored into the flags value, then only these |
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271 | backends will be tried (in the reverse order as given here). If none are |
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272 | specified, most compiled-in backend will be tried, usually in reverse |
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273 | order of their flag values :)</p> |
202 | </dd> |
274 | </dd> |
203 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
275 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
204 | <dd> |
276 | <dd> |
205 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
277 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
206 | always distinct from the default loop. Unlike the default loop, it cannot |
278 | always distinct from the default loop. Unlike the default loop, it cannot |
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222 | <dd> |
294 | <dd> |
223 | <p>This function reinitialises the kernel state for backends that have |
295 | <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 |
296 | 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 |
297 | after forking, in either the parent or child process (or both, but that |
226 | again makes little sense).</p> |
298 | again makes little sense).</p> |
227 | <p>You <i>must</i> call this function after forking if and only if you want to |
299 | <p>You <i>must</i> call this function in the child process after forking if and |
228 | use the event library in both processes. If you just fork+exec, you don't |
300 | only if you want to use the event library in both processes. If you just |
229 | have to call it.</p> |
301 | 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 |
302 | <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 |
303 | 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> |
304 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
233 | <pre> pthread_atfork (0, 0, ev_default_fork); |
305 | <pre> pthread_atfork (0, 0, ev_default_fork); |
234 | |
306 | |
235 | </pre> |
307 | </pre> |
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308 | <p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use |
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309 | without calling this function, so if you force one of those backends you |
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310 | do not need to care.</p> |
236 | </dd> |
311 | </dd> |
237 | <dt>ev_loop_fork (loop)</dt> |
312 | <dt>ev_loop_fork (loop)</dt> |
238 | <dd> |
313 | <dd> |
239 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
314 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
240 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
315 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
241 | after fork, and how you do this is entirely your own problem.</p> |
316 | after fork, and how you do this is entirely your own problem.</p> |
242 | </dd> |
317 | </dd> |
243 | <dt>unsigned int ev_method (loop)</dt> |
318 | <dt>unsigned int ev_backend (loop)</dt> |
244 | <dd> |
319 | <dd> |
245 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
320 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
246 | use.</p> |
321 | use.</p> |
247 | </dd> |
322 | </dd> |
248 | <dt>ev_tstamp ev_now (loop)</dt> |
323 | <dt>ev_tstamp ev_now (loop)</dt> |
249 | <dd> |
324 | <dd> |
250 | <p>Returns the current "event loop time", which is the time the event loop |
325 | <p>Returns the current "event loop time", which is the time the event loop |
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268 | your process until at least one new event arrives, and will return after |
343 | your process until at least one new event arrives, and will return after |
269 | one iteration of the loop.</p> |
344 | one iteration of the loop.</p> |
270 | <p>This flags value could be used to implement alternative looping |
345 | <p>This flags value could be used to implement alternative looping |
271 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
346 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
272 | more generic mechanism.</p> |
347 | more generic mechanism.</p> |
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348 | <p>Here are the gory details of what ev_loop does:</p> |
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349 | <pre> 1. If there are no active watchers (reference count is zero), return. |
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350 | 2. Queue and immediately call all prepare watchers. |
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351 | 3. If we have been forked, recreate the kernel state. |
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352 | 4. Update the kernel state with all outstanding changes. |
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353 | 5. Update the "event loop time". |
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354 | 6. Calculate for how long to block. |
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355 | 7. Block the process, waiting for events. |
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356 | 8. Update the "event loop time" and do time jump handling. |
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357 | 9. Queue all outstanding timers. |
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358 | 10. Queue all outstanding periodics. |
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359 | 11. If no events are pending now, queue all idle watchers. |
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360 | 12. Queue all check watchers. |
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361 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
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362 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
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363 | was used, return, otherwise continue with step #1. |
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364 | |
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365 | </pre> |
273 | </dd> |
366 | </dd> |
274 | <dt>ev_unloop (loop, how)</dt> |
367 | <dt>ev_unloop (loop, how)</dt> |
275 | <dd> |
368 | <dd> |
276 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
369 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
277 | has processed all outstanding events). The <code>how</code> argument must be either |
370 | has processed all outstanding events). The <code>how</code> argument must be either |
278 | <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> call return, or |
371 | <code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or |
279 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
372 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
280 | </dd> |
373 | </dd> |
281 | <dt>ev_ref (loop)</dt> |
374 | <dt>ev_ref (loop)</dt> |
282 | <dt>ev_unref (loop)</dt> |
375 | <dt>ev_unref (loop)</dt> |
283 | <dd> |
376 | <dd> |
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330 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
423 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
331 | *)</code>), and you can stop watching for events at any time by calling the |
424 | *)</code>), and you can stop watching for events at any time by calling the |
332 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
425 | 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 |
426 | <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 |
427 | must not touch the values stored in it. Most specifically you must never |
335 | reinitialise it or call its set method.</p> |
428 | reinitialise it or call its set macro.</p> |
336 | <p>You can check whether an event is active by calling the <code>ev_is_active |
429 | <p>You can check whether an event is active by calling the <code>ev_is_active |
337 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
430 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
338 | callback for it has not been called yet) you can use the <code>ev_is_pending |
431 | callback for it has not been called yet) you can use the <code>ev_is_pending |
339 | (watcher *)</code> macro.</p> |
432 | (watcher *)</code> macro.</p> |
340 | <p>Each and every callback receives the event loop pointer as first, the |
433 | <p>Each and every callback receives the event loop pointer as first, the |
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449 | descriptors to non-blocking mode is also usually a good idea (but not |
542 | descriptors to non-blocking mode is also usually a good idea (but not |
450 | required if you know what you are doing).</p> |
543 | required if you know what you are doing).</p> |
451 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
544 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
452 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
545 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
453 | descriptors correctly if you register interest in two or more fds pointing |
546 | descriptors correctly if you register interest in two or more fds pointing |
454 | to the same file/socket etc. description (that is, they share the same |
547 | to the same underlying file/socket etc. description (that is, they share |
455 | underlying "file open").</p> |
548 | the same underlying "file open").</p> |
456 | <p>If you must do this, then force the use of a known-to-be-good backend |
549 | <p>If you must do this, then force the use of a known-to-be-good backend |
457 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
550 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
458 | EVMETHOD_POLL).</p> |
551 | <code>EVBACKEND_POLL</code>).</p> |
459 | <dl> |
552 | <dl> |
460 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
553 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
461 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
554 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
462 | <dd> |
555 | <dd> |
463 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
556 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
464 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
557 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
465 | EV_WRITE</code> to receive the given events.</p> |
558 | EV_WRITE</code> to receive the given events.</p> |
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559 | <p>Please note that most of the more scalable backend mechanisms (for example |
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560 | epoll and solaris ports) can result in spurious readyness notifications |
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561 | for file descriptors, so you practically need to use non-blocking I/O (and |
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562 | treat callback invocation as hint only), or retest separately with a safe |
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563 | interface before doing I/O (XLib can do this), or force the use of either |
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564 | <code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this |
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565 | problem. Also note that it is quite easy to have your callback invoked |
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566 | when the readyness condition is no longer valid even when employing |
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567 | typical ways of handling events, so its a good idea to use non-blocking |
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568 | I/O unconditionally.</p> |
466 | </dd> |
569 | </dd> |
467 | </dl> |
570 | </dl> |
468 | |
571 | |
469 | </div> |
572 | </div> |
470 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
573 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
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472 | <p>Timer watchers are simple relative timers that generate an event after a |
575 | <p>Timer watchers are simple relative timers that generate an event after a |
473 | given time, and optionally repeating in regular intervals after that.</p> |
576 | given time, and optionally repeating in regular intervals after that.</p> |
474 | <p>The timers are based on real time, that is, if you register an event that |
577 | <p>The timers are based on real time, that is, if you register an event that |
475 | times out after an hour and you reset your system clock to last years |
578 | times out after an hour and you reset your system clock to last years |
476 | time, it will still time out after (roughly) and hour. "Roughly" because |
579 | time, it will still time out after (roughly) and hour. "Roughly" because |
477 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
580 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
478 | monotonic clock option helps a lot here).</p> |
581 | monotonic clock option helps a lot here).</p> |
479 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
582 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
480 | time. This is usually the right thing as this timestamp refers to the time |
583 | time. This is usually the right thing as this timestamp refers to the time |
481 | of the event triggering whatever timeout you are modifying/starting. If |
584 | of the event triggering whatever timeout you are modifying/starting. If |
482 | you suspect event processing to be delayed and you *need* to base the timeout |
585 | you suspect event processing to be delayed and you <i>need</i> to base the timeout |
483 | on the current time, use something like this to adjust for this:</p> |
586 | on the current time, use something like this to adjust for this:</p> |
484 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
587 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
485 | |
588 | |
486 | </pre> |
589 | </pre> |
|
|
590 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
591 | but if multiple timers become ready during the same loop iteration then |
|
|
592 | order of execution is undefined.</p> |
487 | <dl> |
593 | <dl> |
488 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
594 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
489 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
595 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
490 | <dd> |
596 | <dd> |
491 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
597 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
529 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
635 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
530 | roughly 10 seconds later and of course not if you reset your system time |
636 | roughly 10 seconds later and of course not if you reset your system time |
531 | again).</p> |
637 | again).</p> |
532 | <p>They can also be used to implement vastly more complex timers, such as |
638 | <p>They can also be used to implement vastly more complex timers, such as |
533 | triggering an event on eahc midnight, local time.</p> |
639 | triggering an event on eahc midnight, local time.</p> |
|
|
640 | <p>As with timers, the callback is guarenteed to be invoked only when the |
|
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641 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
|
|
642 | during the same loop iteration then order of execution is undefined.</p> |
534 | <dl> |
643 | <dl> |
535 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
644 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
536 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
645 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
537 | <dd> |
646 | <dd> |
538 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
647 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
539 | operation, and we will explain them from simplest to complex:</p> |
648 | operation, and we will explain them from simplest to complex:</p> |
540 | |
|
|
541 | |
|
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542 | |
|
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543 | |
|
|
544 | <p> |
649 | <p> |
545 | <dl> |
650 | <dl> |
546 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
651 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
547 | <dd> |
652 | <dd> |
548 | <p>In this configuration the watcher triggers an event at the wallclock time |
653 | <p>In this configuration the watcher triggers an event at the wallclock time |
… | |
… | |
763 | </dl> |
868 | </dl> |
764 | |
869 | |
765 | </div> |
870 | </div> |
766 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
871 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
767 | <div id="LIBEVENT_EMULATION_CONTENT"> |
872 | <div id="LIBEVENT_EMULATION_CONTENT"> |
768 | <p>TBD.</p> |
873 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
874 | emulate the internals of libevent, so here are some usage hints:</p> |
|
|
875 | <dl> |
|
|
876 | <dt>* Use it by including <event.h>, as usual.</dt> |
|
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877 | <dt>* The following members are fully supported: ev_base, ev_callback, |
|
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878 | ev_arg, ev_fd, ev_res, ev_events.</dt> |
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879 | <dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
880 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
881 | it a private API).</dt> |
|
|
882 | <dt>* Priorities are not currently supported. Initialising priorities |
|
|
883 | will fail and all watchers will have the same priority, even though there |
|
|
884 | is an ev_pri field.</dt> |
|
|
885 | <dt>* Other members are not supported.</dt> |
|
|
886 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
|
|
887 | to use the libev header file and library.</dt> |
|
|
888 | </dl> |
769 | |
889 | |
770 | </div> |
890 | </div> |
771 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
891 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
772 | <div id="C_SUPPORT_CONTENT"> |
892 | <div id="C_SUPPORT_CONTENT"> |
773 | <p>TBD.</p> |
893 | <p>TBD.</p> |