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39 | F<README.embed> in the libev distribution. If libev was configured without |
39 | F<README.embed> in the libev distribution. If libev was configured without |
40 | support for multiple event loops, then all functions taking an initial |
40 | support for multiple event loops, then all functions taking an initial |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
42 | will not have this argument. |
42 | will not have this argument. |
43 | |
43 | |
44 | =head1 TIME AND OTHER GLOBAL FUNCTIONS |
44 | =head1 TIME REPRESENTATION |
45 | |
45 | |
46 | Libev represents time as a single floating point number, representing the |
46 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
50 | to the double type in C. |
51 | |
51 | |
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52 | =head1 GLOBAL FUNCTIONS |
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53 | |
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54 | These functions can be called anytime, even before initialising the |
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55 | library in any way. |
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56 | |
52 | =over 4 |
57 | =over 4 |
53 | |
58 | |
54 | =item ev_tstamp ev_time () |
59 | =item ev_tstamp ev_time () |
55 | |
60 | |
56 | Returns the current time as libev would use it. |
61 | Returns the current time as libev would use it. Please note that the |
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62 | C<ev_now> function is usually faster and also often returns the timestamp |
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63 | you actually want to know. |
57 | |
64 | |
58 | =item int ev_version_major () |
65 | =item int ev_version_major () |
59 | |
66 | |
60 | =item int ev_version_minor () |
67 | =item int ev_version_minor () |
61 | |
68 | |
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67 | |
74 | |
68 | Usually, it's a good idea to terminate if the major versions mismatch, |
75 | Usually, it's a good idea to terminate if the major versions mismatch, |
69 | as this indicates an incompatible change. Minor versions are usually |
76 | as this indicates an incompatible change. Minor versions are usually |
70 | compatible to older versions, so a larger minor version alone is usually |
77 | compatible to older versions, so a larger minor version alone is usually |
71 | not a problem. |
78 | not a problem. |
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79 | |
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80 | =item unsigned int ev_supported_backends () |
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81 | |
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82 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
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83 | value) compiled into this binary of libev (independent of their |
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84 | availability on the system you are running on). See C<ev_default_loop> for |
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85 | a description of the set values. |
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86 | |
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87 | =item unsigned int ev_recommended_backends () |
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88 | |
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89 | Return the set of all backends compiled into this binary of libev and also |
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90 | recommended for this platform. This set is often smaller than the one |
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91 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
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92 | most BSDs and will not be autodetected unless you explicitly request it |
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93 | (assuming you know what you are doing). This is the set of backends that |
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94 | libev will probe for if you specify no backends explicitly. |
72 | |
95 | |
73 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
96 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
74 | |
97 | |
75 | Sets the allocation function to use (the prototype is similar to the |
98 | Sets the allocation function to use (the prototype is similar to the |
76 | realloc C function, the semantics are identical). It is used to allocate |
99 | realloc C function, the semantics are identical). It is used to allocate |
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99 | An event loop is described by a C<struct ev_loop *>. The library knows two |
122 | An event loop is described by a C<struct ev_loop *>. The library knows two |
100 | types of such loops, the I<default> loop, which supports signals and child |
123 | types of such loops, the I<default> loop, which supports signals and child |
101 | events, and dynamically created loops which do not. |
124 | events, and dynamically created loops which do not. |
102 | |
125 | |
103 | If you use threads, a common model is to run the default event loop |
126 | If you use threads, a common model is to run the default event loop |
104 | in your main thread (or in a separate thrad) and for each thread you |
127 | in your main thread (or in a separate thread) and for each thread you |
105 | create, you also create another event loop. Libev itself does no locking |
128 | create, you also create another event loop. Libev itself does no locking |
106 | whatsoever, so if you mix calls to the same event loop in different |
129 | whatsoever, so if you mix calls to the same event loop in different |
107 | threads, make sure you lock (this is usually a bad idea, though, even if |
130 | threads, make sure you lock (this is usually a bad idea, though, even if |
108 | done correctly, because it's hideous and inefficient). |
131 | done correctly, because it's hideous and inefficient). |
109 | |
132 | |
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112 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
135 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
113 | |
136 | |
114 | This will initialise the default event loop if it hasn't been initialised |
137 | This will initialise the default event loop if it hasn't been initialised |
115 | yet and return it. If the default loop could not be initialised, returns |
138 | yet and return it. If the default loop could not be initialised, returns |
116 | false. If it already was initialised it simply returns it (and ignores the |
139 | false. If it already was initialised it simply returns it (and ignores the |
117 | flags). |
140 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
118 | |
141 | |
119 | If you don't know what event loop to use, use the one returned from this |
142 | If you don't know what event loop to use, use the one returned from this |
120 | function. |
143 | function. |
121 | |
144 | |
122 | The flags argument can be used to specify special behaviour or specific |
145 | The flags argument can be used to specify special behaviour or specific |
123 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO). |
146 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
124 | |
147 | |
125 | It supports the following flags: |
148 | The following flags are supported: |
126 | |
149 | |
127 | =over 4 |
150 | =over 4 |
128 | |
151 | |
129 | =item C<EVFLAG_AUTO> |
152 | =item C<EVFLAG_AUTO> |
130 | |
153 | |
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138 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
161 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
139 | override the flags completely if it is found in the environment. This is |
162 | override the flags completely if it is found in the environment. This is |
140 | useful to try out specific backends to test their performance, or to work |
163 | useful to try out specific backends to test their performance, or to work |
141 | around bugs. |
164 | around bugs. |
142 | |
165 | |
143 | =item C<EVMETHOD_SELECT> (portable select backend) |
166 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
144 | |
167 | |
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168 | This is your standard select(2) backend. Not I<completely> standard, as |
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169 | libev tries to roll its own fd_set with no limits on the number of fds, |
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170 | but if that fails, expect a fairly low limit on the number of fds when |
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171 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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172 | the fastest backend for a low number of fds. |
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173 | |
145 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
174 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
146 | |
175 | |
147 | =item C<EVMETHOD_EPOLL> (linux only) |
176 | And this is your standard poll(2) backend. It's more complicated than |
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177 | select, but handles sparse fds better and has no artificial limit on the |
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178 | number of fds you can use (except it will slow down considerably with a |
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179 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
148 | |
180 | |
149 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
181 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
150 | |
182 | |
151 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
183 | For few fds, this backend is a bit little slower than poll and select, |
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184 | but it scales phenomenally better. While poll and select usually scale like |
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185 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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186 | either O(1) or O(active_fds). |
152 | |
187 | |
153 | =item C<EVMETHOD_PORT> (solaris 10 only) |
188 | While stopping and starting an I/O watcher in the same iteration will |
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189 | result in some caching, there is still a syscall per such incident |
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190 | (because the fd could point to a different file description now), so its |
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191 | best to avoid that. Also, dup()ed file descriptors might not work very |
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192 | well if you register events for both fds. |
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193 | |
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194 | Please note that epoll sometimes generates spurious notifications, so you |
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195 | need to use non-blocking I/O or other means to avoid blocking when no data |
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196 | (or space) is available. |
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197 | |
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198 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
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199 | |
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200 | Kqueue deserves special mention, as at the time of this writing, it |
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201 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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202 | anything but sockets and pipes, except on Darwin, where of course its |
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203 | completely useless). For this reason its not being "autodetected" |
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204 | unless you explicitly specify it explicitly in the flags (i.e. using |
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205 | C<EVBACKEND_KQUEUE>). |
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206 | |
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207 | It scales in the same way as the epoll backend, but the interface to the |
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208 | kernel is more efficient (which says nothing about its actual speed, of |
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209 | course). While starting and stopping an I/O watcher does not cause an |
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210 | extra syscall as with epoll, it still adds up to four event changes per |
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211 | incident, so its best to avoid that. |
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212 | |
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213 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
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214 | |
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215 | This is not implemented yet (and might never be). |
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216 | |
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217 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
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218 | |
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219 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
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220 | it's really slow, but it still scales very well (O(active_fds)). |
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221 | |
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222 | Please note that solaris ports can result in a lot of spurious |
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223 | notifications, so you need to use non-blocking I/O or other means to avoid |
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224 | blocking when no data (or space) is available. |
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225 | |
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226 | =item C<EVBACKEND_ALL> |
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227 | |
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228 | Try all backends (even potentially broken ones that wouldn't be tried |
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229 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
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230 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
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231 | |
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232 | =back |
154 | |
233 | |
155 | If one or more of these are ored into the flags value, then only these |
234 | If one or more of these are ored into the flags value, then only these |
156 | backends will be tried (in the reverse order as given here). If one are |
235 | backends will be tried (in the reverse order as given here). If none are |
157 | specified, any backend will do. |
236 | specified, most compiled-in backend will be tried, usually in reverse |
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237 | order of their flag values :) |
158 | |
238 | |
159 | =back |
239 | The most typical usage is like this: |
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240 | |
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241 | if (!ev_default_loop (0)) |
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242 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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243 | |
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244 | Restrict libev to the select and poll backends, and do not allow |
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245 | environment settings to be taken into account: |
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246 | |
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247 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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248 | |
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249 | Use whatever libev has to offer, but make sure that kqueue is used if |
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250 | available (warning, breaks stuff, best use only with your own private |
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251 | event loop and only if you know the OS supports your types of fds): |
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252 | |
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253 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
160 | |
254 | |
161 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
255 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
162 | |
256 | |
163 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
257 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
164 | always distinct from the default loop. Unlike the default loop, it cannot |
258 | always distinct from the default loop. Unlike the default loop, it cannot |
… | |
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181 | This function reinitialises the kernel state for backends that have |
275 | This function reinitialises the kernel state for backends that have |
182 | one. Despite the name, you can call it anytime, but it makes most sense |
276 | one. Despite the name, you can call it anytime, but it makes most sense |
183 | after forking, in either the parent or child process (or both, but that |
277 | after forking, in either the parent or child process (or both, but that |
184 | again makes little sense). |
278 | again makes little sense). |
185 | |
279 | |
186 | You I<must> call this function after forking if and only if you want to |
280 | You I<must> call this function in the child process after forking if and |
187 | use the event library in both processes. If you just fork+exec, you don't |
281 | only if you want to use the event library in both processes. If you just |
188 | have to call it. |
282 | fork+exec, you don't have to call it. |
189 | |
283 | |
190 | The function itself is quite fast and it's usually not a problem to call |
284 | The function itself is quite fast and it's usually not a problem to call |
191 | it just in case after a fork. To make this easy, the function will fit in |
285 | it just in case after a fork. To make this easy, the function will fit in |
192 | quite nicely into a call to C<pthread_atfork>: |
286 | quite nicely into a call to C<pthread_atfork>: |
193 | |
287 | |
194 | pthread_atfork (0, 0, ev_default_fork); |
288 | pthread_atfork (0, 0, ev_default_fork); |
195 | |
289 | |
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290 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
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291 | without calling this function, so if you force one of those backends you |
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292 | do not need to care. |
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293 | |
196 | =item ev_loop_fork (loop) |
294 | =item ev_loop_fork (loop) |
197 | |
295 | |
198 | Like C<ev_default_fork>, but acts on an event loop created by |
296 | Like C<ev_default_fork>, but acts on an event loop created by |
199 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
297 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
200 | after fork, and how you do this is entirely your own problem. |
298 | after fork, and how you do this is entirely your own problem. |
201 | |
299 | |
202 | =item unsigned int ev_method (loop) |
300 | =item unsigned int ev_backend (loop) |
203 | |
301 | |
204 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
302 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
205 | use. |
303 | use. |
206 | |
304 | |
207 | =item ev_tstamp ev_now (loop) |
305 | =item ev_tstamp ev_now (loop) |
208 | |
306 | |
209 | Returns the current "event loop time", which is the time the event loop |
307 | Returns the current "event loop time", which is the time the event loop |
… | |
… | |
216 | |
314 | |
217 | Finally, this is it, the event handler. This function usually is called |
315 | Finally, this is it, the event handler. This function usually is called |
218 | after you initialised all your watchers and you want to start handling |
316 | after you initialised all your watchers and you want to start handling |
219 | events. |
317 | events. |
220 | |
318 | |
221 | If the flags argument is specified as 0, it will not return until either |
319 | If the flags argument is specified as C<0>, it will not return until |
222 | no event watchers are active anymore or C<ev_unloop> was called. |
320 | either no event watchers are active anymore or C<ev_unloop> was called. |
223 | |
321 | |
224 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
322 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
225 | those events and any outstanding ones, but will not block your process in |
323 | those events and any outstanding ones, but will not block your process in |
226 | case there are no events and will return after one iteration of the loop. |
324 | case there are no events and will return after one iteration of the loop. |
227 | |
325 | |
228 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
326 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
229 | neccessary) and will handle those and any outstanding ones. It will block |
327 | neccessary) and will handle those and any outstanding ones. It will block |
230 | your process until at least one new event arrives, and will return after |
328 | your process until at least one new event arrives, and will return after |
231 | one iteration of the loop. |
329 | one iteration of the loop. This is useful if you are waiting for some |
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330 | external event in conjunction with something not expressible using other |
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331 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
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332 | usually a better approach for this kind of thing. |
232 | |
333 | |
233 | This flags value could be used to implement alternative looping |
334 | Here are the gory details of what C<ev_loop> does: |
234 | constructs, but the C<prepare> and C<check> watchers provide a better and |
335 | |
235 | more generic mechanism. |
336 | * If there are no active watchers (reference count is zero), return. |
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337 | - Queue prepare watchers and then call all outstanding watchers. |
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338 | - If we have been forked, recreate the kernel state. |
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339 | - Update the kernel state with all outstanding changes. |
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340 | - Update the "event loop time". |
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341 | - Calculate for how long to block. |
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342 | - Block the process, waiting for any events. |
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343 | - Queue all outstanding I/O (fd) events. |
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344 | - Update the "event loop time" and do time jump handling. |
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345 | - Queue all outstanding timers. |
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346 | - Queue all outstanding periodics. |
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347 | - If no events are pending now, queue all idle watchers. |
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348 | - Queue all check watchers. |
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349 | - Call all queued watchers in reverse order (i.e. check watchers first). |
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350 | Signals and child watchers are implemented as I/O watchers, and will |
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351 | be handled here by queueing them when their watcher gets executed. |
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352 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
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353 | were used, return, otherwise continue with step *. |
236 | |
354 | |
237 | =item ev_unloop (loop, how) |
355 | =item ev_unloop (loop, how) |
238 | |
356 | |
239 | Can be used to make a call to C<ev_loop> return early (but only after it |
357 | Can be used to make a call to C<ev_loop> return early (but only after it |
240 | has processed all outstanding events). The C<how> argument must be either |
358 | has processed all outstanding events). The C<how> argument must be either |
241 | C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or |
359 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
242 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
360 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
243 | |
361 | |
244 | =item ev_ref (loop) |
362 | =item ev_ref (loop) |
245 | |
363 | |
246 | =item ev_unref (loop) |
364 | =item ev_unref (loop) |
… | |
… | |
297 | *) >>), and you can stop watching for events at any time by calling the |
415 | *) >>), and you can stop watching for events at any time by calling the |
298 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
416 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
299 | |
417 | |
300 | As long as your watcher is active (has been started but not stopped) you |
418 | As long as your watcher is active (has been started but not stopped) you |
301 | must not touch the values stored in it. Most specifically you must never |
419 | must not touch the values stored in it. Most specifically you must never |
302 | reinitialise it or call its set method. |
420 | reinitialise it or call its set macro. |
303 | |
421 | |
304 | You can check whether an event is active by calling the C<ev_is_active |
422 | You can check whether an event is active by calling the C<ev_is_active |
305 | (watcher *)> macro. To see whether an event is outstanding (but the |
423 | (watcher *)> macro. To see whether an event is outstanding (but the |
306 | callback for it has not been called yet) you can use the C<ev_is_pending |
424 | callback for it has not been called yet) you can use the C<ev_is_pending |
307 | (watcher *)> macro. |
425 | (watcher *)> macro. |
… | |
… | |
412 | in each iteration of the event loop (This behaviour is called |
530 | in each iteration of the event loop (This behaviour is called |
413 | level-triggering because you keep receiving events as long as the |
531 | level-triggering because you keep receiving events as long as the |
414 | condition persists. Remember you can stop the watcher if you don't want to |
532 | condition persists. Remember you can stop the watcher if you don't want to |
415 | act on the event and neither want to receive future events). |
533 | act on the event and neither want to receive future events). |
416 | |
534 | |
417 | In general you can register as many read and/or write event watchers oer |
535 | In general you can register as many read and/or write event watchers per |
418 | fd as you want (as long as you don't confuse yourself). Setting all file |
536 | fd as you want (as long as you don't confuse yourself). Setting all file |
419 | descriptors to non-blocking mode is also usually a good idea (but not |
537 | descriptors to non-blocking mode is also usually a good idea (but not |
420 | required if you know what you are doing). |
538 | required if you know what you are doing). |
421 | |
539 | |
422 | You have to be careful with dup'ed file descriptors, though. Some backends |
540 | You have to be careful with dup'ed file descriptors, though. Some backends |
423 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
541 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
424 | descriptors correctly if you register interest in two or more fds pointing |
542 | descriptors correctly if you register interest in two or more fds pointing |
425 | to the same file/socket etc. description. |
543 | to the same underlying file/socket etc. description (that is, they share |
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544 | the same underlying "file open"). |
426 | |
545 | |
427 | If you must do this, then force the use of a known-to-be-good backend |
546 | If you must do this, then force the use of a known-to-be-good backend |
428 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
547 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
429 | EVMETHOD_POLL). |
548 | C<EVBACKEND_POLL>). |
430 | |
549 | |
431 | =over 4 |
550 | =over 4 |
432 | |
551 | |
433 | =item ev_io_init (ev_io *, callback, int fd, int events) |
552 | =item ev_io_init (ev_io *, callback, int fd, int events) |
434 | |
553 | |
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… | |
436 | |
555 | |
437 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
556 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
438 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
557 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
439 | EV_WRITE> to receive the given events. |
558 | EV_WRITE> to receive the given events. |
440 | |
559 | |
|
|
560 | Please note that most of the more scalable backend mechanisms (for example |
|
|
561 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
562 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
563 | treat callback invocation as hint only), or retest separately with a safe |
|
|
564 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
565 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
|
|
566 | problem. Also note that it is quite easy to have your callback invoked |
|
|
567 | when the readyness condition is no longer valid even when employing |
|
|
568 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
569 | I/O unconditionally. |
|
|
570 | |
441 | =back |
571 | =back |
442 | |
572 | |
443 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
573 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
444 | |
574 | |
445 | Timer watchers are simple relative timers that generate an event after a |
575 | Timer watchers are simple relative timers that generate an event after a |
446 | given time, and optionally repeating in regular intervals after that. |
576 | given time, and optionally repeating in regular intervals after that. |
447 | |
577 | |
448 | The timers are based on real time, that is, if you register an event that |
578 | The timers are based on real time, that is, if you register an event that |
449 | times out after an hour and youreset your system clock to last years |
579 | times out after an hour and you reset your system clock to last years |
450 | time, it will still time out after (roughly) and hour. "Roughly" because |
580 | time, it will still time out after (roughly) and hour. "Roughly" because |
451 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
581 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
452 | monotonic clock option helps a lot here). |
582 | monotonic clock option helps a lot here). |
453 | |
583 | |
454 | The relative timeouts are calculated relative to the C<ev_now ()> |
584 | The relative timeouts are calculated relative to the C<ev_now ()> |
455 | time. This is usually the right thing as this timestamp refers to the time |
585 | time. This is usually the right thing as this timestamp refers to the time |
456 | of the event triggering whatever timeout you are modifying/starting. If |
586 | of the event triggering whatever timeout you are modifying/starting. If |
457 | you suspect event processing to be delayed and you *need* to base the timeout |
587 | you suspect event processing to be delayed and you I<need> to base the timeout |
458 | ion the current time, use something like this to adjust for this: |
588 | on the current time, use something like this to adjust for this: |
459 | |
589 | |
460 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
590 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
591 | |
|
|
592 | The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
593 | but if multiple timers become ready during the same loop iteration then |
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|
594 | order of execution is undefined. |
461 | |
595 | |
462 | =over 4 |
596 | =over 4 |
463 | |
597 | |
464 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
598 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
465 | |
599 | |
… | |
… | |
471 | later, again, and again, until stopped manually. |
605 | later, again, and again, until stopped manually. |
472 | |
606 | |
473 | The timer itself will do a best-effort at avoiding drift, that is, if you |
607 | The timer itself will do a best-effort at avoiding drift, that is, if you |
474 | configure a timer to trigger every 10 seconds, then it will trigger at |
608 | configure a timer to trigger every 10 seconds, then it will trigger at |
475 | exactly 10 second intervals. If, however, your program cannot keep up with |
609 | exactly 10 second intervals. If, however, your program cannot keep up with |
476 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
610 | the timer (because it takes longer than those 10 seconds to do stuff) the |
477 | timer will not fire more than once per event loop iteration. |
611 | timer will not fire more than once per event loop iteration. |
478 | |
612 | |
479 | =item ev_timer_again (loop) |
613 | =item ev_timer_again (loop) |
480 | |
614 | |
481 | This will act as if the timer timed out and restart it again if it is |
615 | This will act as if the timer timed out and restart it again if it is |
… | |
… | |
512 | again). |
646 | again). |
513 | |
647 | |
514 | They can also be used to implement vastly more complex timers, such as |
648 | They can also be used to implement vastly more complex timers, such as |
515 | triggering an event on eahc midnight, local time. |
649 | triggering an event on eahc midnight, local time. |
516 | |
650 | |
|
|
651 | As with timers, the callback is guarenteed to be invoked only when the |
|
|
652 | time (C<at>) has been passed, but if multiple periodic timers become ready |
|
|
653 | during the same loop iteration then order of execution is undefined. |
|
|
654 | |
517 | =over 4 |
655 | =over 4 |
518 | |
656 | |
519 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
657 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
520 | |
658 | |
521 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
659 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
522 | |
660 | |
523 | Lots of arguments, lets sort it out... There are basically three modes of |
661 | Lots of arguments, lets sort it out... There are basically three modes of |
524 | operation, and we will explain them from simplest to complex: |
662 | operation, and we will explain them from simplest to complex: |
525 | |
|
|
526 | |
663 | |
527 | =over 4 |
664 | =over 4 |
528 | |
665 | |
529 | =item * absolute timer (interval = reschedule_cb = 0) |
666 | =item * absolute timer (interval = reschedule_cb = 0) |
530 | |
667 | |
… | |
… | |
558 | In this mode the values for C<interval> and C<at> are both being |
695 | In this mode the values for C<interval> and C<at> are both being |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
696 | ignored. Instead, each time the periodic watcher gets scheduled, the |
560 | reschedule callback will be called with the watcher as first, and the |
697 | reschedule callback will be called with the watcher as first, and the |
561 | current time as second argument. |
698 | current time as second argument. |
562 | |
699 | |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
700 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
564 | periodic watcher, ever, or make any event loop modifications>. If you need |
701 | ever, or make any event loop modifications>. If you need to stop it, |
565 | to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards. |
702 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
566 | |
703 | starting a prepare watcher). |
567 | Also, I<< this callback must always return a time that is later than the |
|
|
568 | passed C<now> value >>. Not even C<now> itself will be ok. |
|
|
569 | |
704 | |
570 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
705 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
571 | ev_tstamp now)>, e.g.: |
706 | ev_tstamp now)>, e.g.: |
572 | |
707 | |
573 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
708 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
578 | It must return the next time to trigger, based on the passed time value |
713 | It must return the next time to trigger, based on the passed time value |
579 | (that is, the lowest time value larger than to the second argument). It |
714 | (that is, the lowest time value larger than to the second argument). It |
580 | will usually be called just before the callback will be triggered, but |
715 | will usually be called just before the callback will be triggered, but |
581 | might be called at other times, too. |
716 | might be called at other times, too. |
582 | |
717 | |
|
|
718 | NOTE: I<< This callback must always return a time that is later than the |
|
|
719 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
|
|
720 | |
583 | This can be used to create very complex timers, such as a timer that |
721 | This can be used to create very complex timers, such as a timer that |
584 | triggers on each midnight, local time. To do this, you would calculate the |
722 | triggers on each midnight, local time. To do this, you would calculate the |
585 | next midnight after C<now> and return the timestamp value for this. How you do this |
723 | next midnight after C<now> and return the timestamp value for this. How |
586 | is, again, up to you (but it is not trivial). |
724 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
725 | reason I omitted it as an example). |
587 | |
726 | |
588 | =back |
727 | =back |
589 | |
728 | |
590 | =item ev_periodic_again (loop, ev_periodic *) |
729 | =item ev_periodic_again (loop, ev_periodic *) |
591 | |
730 | |
… | |
… | |
670 | =back |
809 | =back |
671 | |
810 | |
672 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
811 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
673 | |
812 | |
674 | Prepare and check watchers are usually (but not always) used in tandem: |
813 | Prepare and check watchers are usually (but not always) used in tandem: |
675 | Prepare watchers get invoked before the process blocks and check watchers |
814 | prepare watchers get invoked before the process blocks and check watchers |
676 | afterwards. |
815 | afterwards. |
677 | |
816 | |
678 | Their main purpose is to integrate other event mechanisms into libev. This |
817 | Their main purpose is to integrate other event mechanisms into libev. This |
679 | could be used, for example, to track variable changes, implement your own |
818 | could be used, for example, to track variable changes, implement your own |
680 | watchers, integrate net-snmp or a coroutine library and lots more. |
819 | watchers, integrate net-snmp or a coroutine library and lots more. |
… | |
… | |
683 | to be watched by the other library, registering C<ev_io> watchers for |
822 | to be watched by the other library, registering C<ev_io> watchers for |
684 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
823 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
685 | provide just this functionality). Then, in the check watcher you check for |
824 | provide just this functionality). Then, in the check watcher you check for |
686 | any events that occured (by checking the pending status of all watchers |
825 | any events that occured (by checking the pending status of all watchers |
687 | and stopping them) and call back into the library. The I/O and timer |
826 | and stopping them) and call back into the library. The I/O and timer |
688 | callbacks will never actually be called (but must be valid neverthelles, |
827 | callbacks will never actually be called (but must be valid nevertheless, |
689 | because you never know, you know?). |
828 | because you never know, you know?). |
690 | |
829 | |
691 | As another example, the Perl Coro module uses these hooks to integrate |
830 | As another example, the Perl Coro module uses these hooks to integrate |
692 | coroutines into libev programs, by yielding to other active coroutines |
831 | coroutines into libev programs, by yielding to other active coroutines |
693 | during each prepare and only letting the process block if no coroutines |
832 | during each prepare and only letting the process block if no coroutines |
694 | are ready to run (its actually more complicated, it only runs coroutines |
833 | are ready to run (it's actually more complicated: it only runs coroutines |
695 | with priority higher than the event loop and one lower priority once, |
834 | with priority higher than or equal to the event loop and one coroutine |
696 | using idle watchers to keep the event loop from blocking if lower-priority |
835 | of lower priority, but only once, using idle watchers to keep the event |
697 | coroutines exist, thus mapping low-priority coroutines to idle/background |
836 | loop from blocking if lower-priority coroutines are active, thus mapping |
698 | tasks). |
837 | low-priority coroutines to idle/background tasks). |
699 | |
838 | |
700 | =over 4 |
839 | =over 4 |
701 | |
840 | |
702 | =item ev_prepare_init (ev_prepare *, callback) |
841 | =item ev_prepare_init (ev_prepare *, callback) |
703 | |
842 | |
… | |
… | |
718 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
857 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
719 | |
858 | |
720 | This function combines a simple timer and an I/O watcher, calls your |
859 | This function combines a simple timer and an I/O watcher, calls your |
721 | callback on whichever event happens first and automatically stop both |
860 | callback on whichever event happens first and automatically stop both |
722 | watchers. This is useful if you want to wait for a single event on an fd |
861 | watchers. This is useful if you want to wait for a single event on an fd |
723 | or timeout without havign to allocate/configure/start/stop/free one or |
862 | or timeout without having to allocate/configure/start/stop/free one or |
724 | more watchers yourself. |
863 | more watchers yourself. |
725 | |
864 | |
726 | If C<fd> is less than 0, then no I/O watcher will be started and events |
865 | If C<fd> is less than 0, then no I/O watcher will be started and events |
727 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
866 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
728 | C<events> set will be craeted and started. |
867 | C<events> set will be craeted and started. |
… | |
… | |
731 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
870 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
732 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
871 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
733 | dubious value. |
872 | dubious value. |
734 | |
873 | |
735 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
874 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
736 | passed an events set like normal event callbacks (with a combination of |
875 | passed an C<revents> set like normal event callbacks (a combination of |
737 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
876 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
738 | value passed to C<ev_once>: |
877 | value passed to C<ev_once>: |
739 | |
878 | |
740 | static void stdin_ready (int revents, void *arg) |
879 | static void stdin_ready (int revents, void *arg) |
741 | { |
880 | { |
… | |
… | |
762 | |
901 | |
763 | Feed an event as if the given signal occured (loop must be the default loop!). |
902 | Feed an event as if the given signal occured (loop must be the default loop!). |
764 | |
903 | |
765 | =back |
904 | =back |
766 | |
905 | |
|
|
906 | =head1 LIBEVENT EMULATION |
|
|
907 | |
|
|
908 | Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
909 | emulate the internals of libevent, so here are some usage hints: |
|
|
910 | |
|
|
911 | =over 4 |
|
|
912 | |
|
|
913 | =item * Use it by including <event.h>, as usual. |
|
|
914 | |
|
|
915 | =item * The following members are fully supported: ev_base, ev_callback, |
|
|
916 | ev_arg, ev_fd, ev_res, ev_events. |
|
|
917 | |
|
|
918 | =item * Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
919 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
920 | it a private API). |
|
|
921 | |
|
|
922 | =item * Priorities are not currently supported. Initialising priorities |
|
|
923 | will fail and all watchers will have the same priority, even though there |
|
|
924 | is an ev_pri field. |
|
|
925 | |
|
|
926 | =item * Other members are not supported. |
|
|
927 | |
|
|
928 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
|
|
929 | to use the libev header file and library. |
|
|
930 | |
|
|
931 | =back |
|
|
932 | |
|
|
933 | =head1 C++ SUPPORT |
|
|
934 | |
|
|
935 | TBD. |
|
|
936 | |
767 | =head1 AUTHOR |
937 | =head1 AUTHOR |
768 | |
938 | |
769 | Marc Lehmann <libev@schmorp.de>. |
939 | Marc Lehmann <libev@schmorp.de>. |
770 | |
940 | |