… | |
… | |
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 C<double> type in C, and when you need to do any calculations on |
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51 | it, you should treat it as such. |
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52 | |
51 | |
53 | |
52 | =head1 GLOBAL FUNCTIONS |
54 | =head1 GLOBAL FUNCTIONS |
53 | |
55 | |
54 | These functions can be called anytime, even before initialising the |
56 | These functions can be called anytime, even before initialising the |
55 | library in any way. |
57 | library in any way. |
… | |
… | |
75 | Usually, it's a good idea to terminate if the major versions mismatch, |
77 | Usually, it's a good idea to terminate if the major versions mismatch, |
76 | as this indicates an incompatible change. Minor versions are usually |
78 | as this indicates an incompatible change. Minor versions are usually |
77 | compatible to older versions, so a larger minor version alone is usually |
79 | compatible to older versions, so a larger minor version alone is usually |
78 | not a problem. |
80 | not a problem. |
79 | |
81 | |
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82 | Example: make sure we haven't accidentally been linked against the wrong |
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83 | version: |
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84 | |
|
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85 | assert (("libev version mismatch", |
|
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86 | ev_version_major () == EV_VERSION_MAJOR |
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87 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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88 | |
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89 | =item unsigned int ev_supported_backends () |
|
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90 | |
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91 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
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92 | value) compiled into this binary of libev (independent of their |
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93 | availability on the system you are running on). See C<ev_default_loop> for |
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94 | a description of the set values. |
|
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95 | |
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96 | Example: make sure we have the epoll method, because yeah this is cool and |
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97 | a must have and can we have a torrent of it please!!!11 |
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98 | |
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99 | assert (("sorry, no epoll, no sex", |
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100 | ev_supported_backends () & EVBACKEND_EPOLL)); |
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101 | |
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102 | =item unsigned int ev_recommended_backends () |
|
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103 | |
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104 | Return the set of all backends compiled into this binary of libev and also |
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105 | recommended for this platform. This set is often smaller than the one |
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106 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
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107 | most BSDs and will not be autodetected unless you explicitly request it |
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108 | (assuming you know what you are doing). This is the set of backends that |
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109 | libev will probe for if you specify no backends explicitly. |
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110 | |
80 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
111 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
81 | |
112 | |
82 | Sets the allocation function to use (the prototype is similar to the |
113 | Sets the allocation function to use (the prototype is similar to the |
83 | realloc C function, the semantics are identical). It is used to allocate |
114 | realloc C function, the semantics are identical). It is used to allocate |
84 | and free memory (no surprises here). If it returns zero when memory |
115 | and free memory (no surprises here). If it returns zero when memory |
… | |
… | |
86 | destructive action. The default is your system realloc function. |
117 | destructive action. The default is your system realloc function. |
87 | |
118 | |
88 | You could override this function in high-availability programs to, say, |
119 | You could override this function in high-availability programs to, say, |
89 | free some memory if it cannot allocate memory, to use a special allocator, |
120 | free some memory if it cannot allocate memory, to use a special allocator, |
90 | or even to sleep a while and retry until some memory is available. |
121 | or even to sleep a while and retry until some memory is available. |
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122 | |
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123 | Example: replace the libev allocator with one that waits a bit and then |
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124 | retries: better than mine). |
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125 | |
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126 | static void * |
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127 | persistent_realloc (void *ptr, long size) |
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128 | { |
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129 | for (;;) |
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130 | { |
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131 | void *newptr = realloc (ptr, size); |
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132 | |
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133 | if (newptr) |
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134 | return newptr; |
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135 | |
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136 | sleep (60); |
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137 | } |
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138 | } |
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139 | |
|
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140 | ... |
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141 | ev_set_allocator (persistent_realloc); |
91 | |
142 | |
92 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
143 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
93 | |
144 | |
94 | Set the callback function to call on a retryable syscall error (such |
145 | Set the callback function to call on a retryable syscall error (such |
95 | as failed select, poll, epoll_wait). The message is a printable string |
146 | as failed select, poll, epoll_wait). The message is a printable string |
… | |
… | |
97 | callback is set, then libev will expect it to remedy the sitution, no |
148 | callback is set, then libev will expect it to remedy the sitution, no |
98 | matter what, when it returns. That is, libev will generally retry the |
149 | matter what, when it returns. That is, libev will generally retry the |
99 | requested operation, or, if the condition doesn't go away, do bad stuff |
150 | requested operation, or, if the condition doesn't go away, do bad stuff |
100 | (such as abort). |
151 | (such as abort). |
101 | |
152 | |
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153 | Example: do the same thing as libev does internally: |
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154 | |
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155 | static void |
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156 | fatal_error (const char *msg) |
|
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157 | { |
|
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158 | perror (msg); |
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159 | abort (); |
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160 | } |
|
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161 | |
|
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162 | ... |
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163 | ev_set_syserr_cb (fatal_error); |
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164 | |
102 | =back |
165 | =back |
103 | |
166 | |
104 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
167 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
105 | |
168 | |
106 | An event loop is described by a C<struct ev_loop *>. The library knows two |
169 | An event loop is described by a C<struct ev_loop *>. The library knows two |
… | |
… | |
119 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
182 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
120 | |
183 | |
121 | This will initialise the default event loop if it hasn't been initialised |
184 | This will initialise the default event loop if it hasn't been initialised |
122 | yet and return it. If the default loop could not be initialised, returns |
185 | yet and return it. If the default loop could not be initialised, returns |
123 | false. If it already was initialised it simply returns it (and ignores the |
186 | false. If it already was initialised it simply returns it (and ignores the |
124 | flags). |
187 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
125 | |
188 | |
126 | If you don't know what event loop to use, use the one returned from this |
189 | If you don't know what event loop to use, use the one returned from this |
127 | function. |
190 | function. |
128 | |
191 | |
129 | The flags argument can be used to specify special behaviour or specific |
192 | The flags argument can be used to specify special behaviour or specific |
130 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO). |
193 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
131 | |
194 | |
132 | It supports the following flags: |
195 | The following flags are supported: |
133 | |
196 | |
134 | =over 4 |
197 | =over 4 |
135 | |
198 | |
136 | =item C<EVFLAG_AUTO> |
199 | =item C<EVFLAG_AUTO> |
137 | |
200 | |
… | |
… | |
145 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
208 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
146 | override the flags completely if it is found in the environment. This is |
209 | override the flags completely if it is found in the environment. This is |
147 | useful to try out specific backends to test their performance, or to work |
210 | useful to try out specific backends to test their performance, or to work |
148 | around bugs. |
211 | around bugs. |
149 | |
212 | |
150 | =item C<EVMETHOD_SELECT> (value 1, portable select backend) |
213 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
151 | |
214 | |
152 | This is your standard select(2) backend. Not I<completely> standard, as |
215 | This is your standard select(2) backend. Not I<completely> standard, as |
153 | libev tries to roll its own fd_set with no limits on the number of fds, |
216 | libev tries to roll its own fd_set with no limits on the number of fds, |
154 | but if that fails, expect a fairly low limit on the number of fds when |
217 | but if that fails, expect a fairly low limit on the number of fds when |
155 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
218 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
156 | the fastest backend for a low number of fds. |
219 | the fastest backend for a low number of fds. |
157 | |
220 | |
158 | =item C<EVMETHOD_POLL> (value 2, poll backend, available everywhere except on windows) |
221 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
159 | |
222 | |
160 | And this is your standard poll(2) backend. It's more complicated than |
223 | And this is your standard poll(2) backend. It's more complicated than |
161 | select, but handles sparse fds better and has no artificial limit on the |
224 | select, but handles sparse fds better and has no artificial limit on the |
162 | number of fds you can use (except it will slow down considerably with a |
225 | number of fds you can use (except it will slow down considerably with a |
163 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
226 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
164 | |
227 | |
165 | =item C<EVMETHOD_EPOLL> (value 4, Linux) |
228 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
166 | |
229 | |
167 | For few fds, this backend is a bit little slower than poll and select, |
230 | For few fds, this backend is a bit little slower than poll and select, |
168 | but it scales phenomenally better. While poll and select usually scale like |
231 | but it scales phenomenally better. While poll and select usually scale like |
169 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
232 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
170 | either O(1) or O(active_fds). |
233 | either O(1) or O(active_fds). |
… | |
… | |
173 | result in some caching, there is still a syscall per such incident |
236 | result in some caching, there is still a syscall per such incident |
174 | (because the fd could point to a different file description now), so its |
237 | (because the fd could point to a different file description now), so its |
175 | best to avoid that. Also, dup()ed file descriptors might not work very |
238 | best to avoid that. Also, dup()ed file descriptors might not work very |
176 | well if you register events for both fds. |
239 | well if you register events for both fds. |
177 | |
240 | |
|
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241 | Please note that epoll sometimes generates spurious notifications, so you |
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242 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
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243 | (or space) is available. |
|
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244 | |
178 | =item C<EVMETHOD_KQUEUE> (value 8, most BSD clones) |
245 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
179 | |
246 | |
180 | Kqueue deserves special mention, as at the time of this writing, it |
247 | Kqueue deserves special mention, as at the time of this writing, it |
181 | was broken on all BSDs except NetBSD (usually it doesn't work with |
248 | was broken on all BSDs except NetBSD (usually it doesn't work with |
182 | anything but sockets and pipes, except on Darwin, where of course its |
249 | anything but sockets and pipes, except on Darwin, where of course its |
183 | completely useless). For this reason its not being "autodetected" unless |
250 | completely useless). For this reason its not being "autodetected" |
184 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO). |
251 | unless you explicitly specify it explicitly in the flags (i.e. using |
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252 | C<EVBACKEND_KQUEUE>). |
185 | |
253 | |
186 | It scales in the same way as the epoll backend, but the interface to the |
254 | It scales in the same way as the epoll backend, but the interface to the |
187 | kernel is more efficient (which says nothing about its actual speed, of |
255 | kernel is more efficient (which says nothing about its actual speed, of |
188 | course). While starting and stopping an I/O watcher does not cause an |
256 | course). While starting and stopping an I/O watcher does not cause an |
189 | extra syscall as with epoll, it still adds up to four event changes per |
257 | extra syscall as with epoll, it still adds up to four event changes per |
190 | incident, so its best to avoid that. |
258 | incident, so its best to avoid that. |
191 | |
259 | |
192 | =item C<EVMETHOD_DEVPOLL> (value 16, Solaris 8) |
260 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
193 | |
261 | |
194 | This is not implemented yet (and might never be). |
262 | This is not implemented yet (and might never be). |
195 | |
263 | |
196 | =item C<EVMETHOD_PORT> (value 32, Solaris 10) |
264 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
197 | |
265 | |
198 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
266 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
199 | it's really slow, but it still scales very well (O(active_fds)). |
267 | it's really slow, but it still scales very well (O(active_fds)). |
200 | |
268 | |
|
|
269 | Please note that solaris ports can result in a lot of spurious |
|
|
270 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
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271 | blocking when no data (or space) is available. |
|
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272 | |
201 | =item C<EVMETHOD_ALL> |
273 | =item C<EVBACKEND_ALL> |
202 | |
274 | |
203 | Try all backends (even potentially broken ones that wouldn't be tried |
275 | Try all backends (even potentially broken ones that wouldn't be tried |
204 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
276 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
205 | C<EVMETHOD_ALL & ~EVMETHOD_KQUEUE>. |
277 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
206 | |
278 | |
207 | =back |
279 | =back |
208 | |
280 | |
209 | If one or more of these are ored into the flags value, then only these |
281 | If one or more of these are ored into the flags value, then only these |
210 | backends will be tried (in the reverse order as given here). If none are |
282 | backends will be tried (in the reverse order as given here). If none are |
211 | specified, most compiled-in backend will be tried, usually in reverse |
283 | specified, most compiled-in backend will be tried, usually in reverse |
212 | order of their flag values :) |
284 | order of their flag values :) |
213 | |
285 | |
|
|
286 | The most typical usage is like this: |
|
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287 | |
|
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288 | if (!ev_default_loop (0)) |
|
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289 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
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290 | |
|
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291 | Restrict libev to the select and poll backends, and do not allow |
|
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292 | environment settings to be taken into account: |
|
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293 | |
|
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294 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
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295 | |
|
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296 | Use whatever libev has to offer, but make sure that kqueue is used if |
|
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297 | available (warning, breaks stuff, best use only with your own private |
|
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298 | event loop and only if you know the OS supports your types of fds): |
|
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299 | |
|
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300 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
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301 | |
214 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
302 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
215 | |
303 | |
216 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
304 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
217 | always distinct from the default loop. Unlike the default loop, it cannot |
305 | always distinct from the default loop. Unlike the default loop, it cannot |
218 | handle signal and child watchers, and attempts to do so will be greeted by |
306 | handle signal and child watchers, and attempts to do so will be greeted by |
219 | undefined behaviour (or a failed assertion if assertions are enabled). |
307 | undefined behaviour (or a failed assertion if assertions are enabled). |
220 | |
308 | |
|
|
309 | Example: try to create a event loop that uses epoll and nothing else. |
|
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310 | |
|
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311 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
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312 | if (!epoller) |
|
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313 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
|
314 | |
221 | =item ev_default_destroy () |
315 | =item ev_default_destroy () |
222 | |
316 | |
223 | Destroys the default loop again (frees all memory and kernel state |
317 | Destroys the default loop again (frees all memory and kernel state |
224 | etc.). This stops all registered event watchers (by not touching them in |
318 | etc.). This stops all registered event watchers (by not touching them in |
225 | any way whatsoever, although you cannot rely on this :). |
319 | any way whatsoever, although you cannot rely on this :). |
… | |
… | |
234 | This function reinitialises the kernel state for backends that have |
328 | This function reinitialises the kernel state for backends that have |
235 | one. Despite the name, you can call it anytime, but it makes most sense |
329 | one. Despite the name, you can call it anytime, but it makes most sense |
236 | after forking, in either the parent or child process (or both, but that |
330 | after forking, in either the parent or child process (or both, but that |
237 | again makes little sense). |
331 | again makes little sense). |
238 | |
332 | |
239 | You I<must> call this function after forking if and only if you want to |
333 | You I<must> call this function in the child process after forking if and |
240 | use the event library in both processes. If you just fork+exec, you don't |
334 | only if you want to use the event library in both processes. If you just |
241 | have to call it. |
335 | fork+exec, you don't have to call it. |
242 | |
336 | |
243 | The function itself is quite fast and it's usually not a problem to call |
337 | The function itself is quite fast and it's usually not a problem to call |
244 | it just in case after a fork. To make this easy, the function will fit in |
338 | it just in case after a fork. To make this easy, the function will fit in |
245 | quite nicely into a call to C<pthread_atfork>: |
339 | quite nicely into a call to C<pthread_atfork>: |
246 | |
340 | |
247 | pthread_atfork (0, 0, ev_default_fork); |
341 | pthread_atfork (0, 0, ev_default_fork); |
248 | |
342 | |
|
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343 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
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344 | without calling this function, so if you force one of those backends you |
|
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345 | do not need to care. |
|
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346 | |
249 | =item ev_loop_fork (loop) |
347 | =item ev_loop_fork (loop) |
250 | |
348 | |
251 | Like C<ev_default_fork>, but acts on an event loop created by |
349 | Like C<ev_default_fork>, but acts on an event loop created by |
252 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
350 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
253 | after fork, and how you do this is entirely your own problem. |
351 | after fork, and how you do this is entirely your own problem. |
254 | |
352 | |
255 | =item unsigned int ev_method (loop) |
353 | =item unsigned int ev_backend (loop) |
256 | |
354 | |
257 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
355 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
258 | use. |
356 | use. |
259 | |
357 | |
260 | =item ev_tstamp ev_now (loop) |
358 | =item ev_tstamp ev_now (loop) |
261 | |
359 | |
262 | Returns the current "event loop time", which is the time the event loop |
360 | Returns the current "event loop time", which is the time the event loop |
263 | got events and started processing them. This timestamp does not change |
361 | received events and started processing them. This timestamp does not |
264 | as long as callbacks are being processed, and this is also the base time |
362 | change as long as callbacks are being processed, and this is also the base |
265 | used for relative timers. You can treat it as the timestamp of the event |
363 | time used for relative timers. You can treat it as the timestamp of the |
266 | occuring (or more correctly, the mainloop finding out about it). |
364 | event occuring (or more correctly, libev finding out about it). |
267 | |
365 | |
268 | =item ev_loop (loop, int flags) |
366 | =item ev_loop (loop, int flags) |
269 | |
367 | |
270 | Finally, this is it, the event handler. This function usually is called |
368 | Finally, this is it, the event handler. This function usually is called |
271 | after you initialised all your watchers and you want to start handling |
369 | after you initialised all your watchers and you want to start handling |
272 | events. |
370 | events. |
273 | |
371 | |
274 | If the flags argument is specified as 0, it will not return until either |
372 | If the flags argument is specified as C<0>, it will not return until |
275 | no event watchers are active anymore or C<ev_unloop> was called. |
373 | either no event watchers are active anymore or C<ev_unloop> was called. |
|
|
374 | |
|
|
375 | Please note that an explicit C<ev_unloop> is usually better than |
|
|
376 | relying on all watchers to be stopped when deciding when a program has |
|
|
377 | finished (especially in interactive programs), but having a program that |
|
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378 | automatically loops as long as it has to and no longer by virtue of |
|
|
379 | relying on its watchers stopping correctly is a thing of beauty. |
276 | |
380 | |
277 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
381 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
278 | those events and any outstanding ones, but will not block your process in |
382 | those events and any outstanding ones, but will not block your process in |
279 | case there are no events and will return after one iteration of the loop. |
383 | case there are no events and will return after one iteration of the loop. |
280 | |
384 | |
281 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
385 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
282 | neccessary) and will handle those and any outstanding ones. It will block |
386 | neccessary) and will handle those and any outstanding ones. It will block |
283 | your process until at least one new event arrives, and will return after |
387 | your process until at least one new event arrives, and will return after |
284 | one iteration of the loop. |
388 | one iteration of the loop. This is useful if you are waiting for some |
|
|
389 | external event in conjunction with something not expressible using other |
|
|
390 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
|
|
391 | usually a better approach for this kind of thing. |
285 | |
392 | |
286 | This flags value could be used to implement alternative looping |
|
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287 | constructs, but the C<prepare> and C<check> watchers provide a better and |
|
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288 | more generic mechanism. |
|
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289 | |
|
|
290 | Here are the gory details of what ev_loop does: |
393 | Here are the gory details of what C<ev_loop> does: |
291 | |
394 | |
292 | 1. If there are no active watchers (reference count is zero), return. |
395 | * If there are no active watchers (reference count is zero), return. |
293 | 2. Queue and immediately call all prepare watchers. |
396 | - Queue prepare watchers and then call all outstanding watchers. |
294 | 3. If we have been forked, recreate the kernel state. |
397 | - If we have been forked, recreate the kernel state. |
295 | 4. Update the kernel state with all outstanding changes. |
398 | - Update the kernel state with all outstanding changes. |
296 | 5. Update the "event loop time". |
399 | - Update the "event loop time". |
297 | 6. Calculate for how long to block. |
400 | - Calculate for how long to block. |
298 | 7. Block the process, waiting for events. |
401 | - Block the process, waiting for any events. |
|
|
402 | - Queue all outstanding I/O (fd) events. |
299 | 8. Update the "event loop time" and do time jump handling. |
403 | - Update the "event loop time" and do time jump handling. |
300 | 9. Queue all outstanding timers. |
404 | - Queue all outstanding timers. |
301 | 10. Queue all outstanding periodics. |
405 | - Queue all outstanding periodics. |
302 | 11. If no events are pending now, queue all idle watchers. |
406 | - If no events are pending now, queue all idle watchers. |
303 | 12. Queue all check watchers. |
407 | - Queue all check watchers. |
304 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
408 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
409 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
410 | be handled here by queueing them when their watcher gets executed. |
305 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
411 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
306 | was used, return, otherwise continue with step #1. |
412 | were used, return, otherwise continue with step *. |
|
|
413 | |
|
|
414 | Example: queue some jobs and then loop until no events are outsanding |
|
|
415 | anymore. |
|
|
416 | |
|
|
417 | ... queue jobs here, make sure they register event watchers as long |
|
|
418 | ... as they still have work to do (even an idle watcher will do..) |
|
|
419 | ev_loop (my_loop, 0); |
|
|
420 | ... jobs done. yeah! |
307 | |
421 | |
308 | =item ev_unloop (loop, how) |
422 | =item ev_unloop (loop, how) |
309 | |
423 | |
310 | Can be used to make a call to C<ev_loop> return early (but only after it |
424 | Can be used to make a call to C<ev_loop> return early (but only after it |
311 | has processed all outstanding events). The C<how> argument must be either |
425 | has processed all outstanding events). The C<how> argument must be either |
… | |
… | |
325 | visible to the libev user and should not keep C<ev_loop> from exiting if |
439 | visible to the libev user and should not keep C<ev_loop> from exiting if |
326 | no event watchers registered by it are active. It is also an excellent |
440 | no event watchers registered by it are active. It is also an excellent |
327 | way to do this for generic recurring timers or from within third-party |
441 | way to do this for generic recurring timers or from within third-party |
328 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
442 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
329 | |
443 | |
|
|
444 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
|
|
445 | running when nothing else is active. |
|
|
446 | |
|
|
447 | struct dv_signal exitsig; |
|
|
448 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
449 | ev_signal_start (myloop, &exitsig); |
|
|
450 | evf_unref (myloop); |
|
|
451 | |
|
|
452 | Example: for some weird reason, unregister the above signal handler again. |
|
|
453 | |
|
|
454 | ev_ref (myloop); |
|
|
455 | ev_signal_stop (myloop, &exitsig); |
|
|
456 | |
330 | =back |
457 | =back |
331 | |
458 | |
332 | =head1 ANATOMY OF A WATCHER |
459 | =head1 ANATOMY OF A WATCHER |
333 | |
460 | |
334 | A watcher is a structure that you create and register to record your |
461 | A watcher is a structure that you create and register to record your |
… | |
… | |
368 | *) >>), and you can stop watching for events at any time by calling the |
495 | *) >>), and you can stop watching for events at any time by calling the |
369 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
496 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
370 | |
497 | |
371 | As long as your watcher is active (has been started but not stopped) you |
498 | As long as your watcher is active (has been started but not stopped) you |
372 | must not touch the values stored in it. Most specifically you must never |
499 | must not touch the values stored in it. Most specifically you must never |
373 | reinitialise it or call its set method. |
500 | reinitialise it or call its set macro. |
374 | |
501 | |
375 | You can check whether an event is active by calling the C<ev_is_active |
502 | You can check whether an event is active by calling the C<ev_is_active |
376 | (watcher *)> macro. To see whether an event is outstanding (but the |
503 | (watcher *)> macro. To see whether an event is outstanding (but the |
377 | callback for it has not been called yet) you can use the C<ev_is_pending |
504 | callback for it has not been called yet) you can use the C<ev_is_pending |
378 | (watcher *)> macro. |
505 | (watcher *)> macro. |
… | |
… | |
475 | =head1 WATCHER TYPES |
602 | =head1 WATCHER TYPES |
476 | |
603 | |
477 | This section describes each watcher in detail, but will not repeat |
604 | This section describes each watcher in detail, but will not repeat |
478 | information given in the last section. |
605 | information given in the last section. |
479 | |
606 | |
|
|
607 | |
480 | =head2 C<ev_io> - is this file descriptor readable or writable |
608 | =head2 C<ev_io> - is this file descriptor readable or writable |
481 | |
609 | |
482 | I/O watchers check whether a file descriptor is readable or writable |
610 | I/O watchers check whether a file descriptor is readable or writable |
483 | in each iteration of the event loop (This behaviour is called |
611 | in each iteration of the event loop (This behaviour is called |
484 | level-triggering because you keep receiving events as long as the |
612 | level-triggering because you keep receiving events as long as the |
… | |
… | |
495 | descriptors correctly if you register interest in two or more fds pointing |
623 | descriptors correctly if you register interest in two or more fds pointing |
496 | to the same underlying file/socket etc. description (that is, they share |
624 | to the same underlying file/socket etc. description (that is, they share |
497 | the same underlying "file open"). |
625 | the same underlying "file open"). |
498 | |
626 | |
499 | If you must do this, then force the use of a known-to-be-good backend |
627 | If you must do this, then force the use of a known-to-be-good backend |
500 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
628 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
501 | EVMETHOD_POLL). |
629 | C<EVBACKEND_POLL>). |
502 | |
630 | |
503 | =over 4 |
631 | =over 4 |
504 | |
632 | |
505 | =item ev_io_init (ev_io *, callback, int fd, int events) |
633 | =item ev_io_init (ev_io *, callback, int fd, int events) |
506 | |
634 | |
… | |
… | |
508 | |
636 | |
509 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
637 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
510 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
638 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
511 | EV_WRITE> to receive the given events. |
639 | EV_WRITE> to receive the given events. |
512 | |
640 | |
|
|
641 | Please note that most of the more scalable backend mechanisms (for example |
|
|
642 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
643 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
644 | treat callback invocation as hint only), or retest separately with a safe |
|
|
645 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
646 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
|
|
647 | problem. Also note that it is quite easy to have your callback invoked |
|
|
648 | when the readyness condition is no longer valid even when employing |
|
|
649 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
650 | I/O unconditionally. |
|
|
651 | |
513 | =back |
652 | =back |
|
|
653 | |
|
|
654 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
|
|
655 | readable, but only once. Since it is likely line-buffered, you could |
|
|
656 | attempt to read a whole line in the callback: |
|
|
657 | |
|
|
658 | static void |
|
|
659 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
660 | { |
|
|
661 | ev_io_stop (loop, w); |
|
|
662 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
663 | } |
|
|
664 | |
|
|
665 | ... |
|
|
666 | struct ev_loop *loop = ev_default_init (0); |
|
|
667 | struct ev_io stdin_readable; |
|
|
668 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
669 | ev_io_start (loop, &stdin_readable); |
|
|
670 | ev_loop (loop, 0); |
|
|
671 | |
514 | |
672 | |
515 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
673 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
516 | |
674 | |
517 | Timer watchers are simple relative timers that generate an event after a |
675 | Timer watchers are simple relative timers that generate an event after a |
518 | given time, and optionally repeating in regular intervals after that. |
676 | given time, and optionally repeating in regular intervals after that. |
… | |
… | |
571 | state where you do not expect data to travel on the socket, you can stop |
729 | state where you do not expect data to travel on the socket, you can stop |
572 | the timer, and again will automatically restart it if need be. |
730 | the timer, and again will automatically restart it if need be. |
573 | |
731 | |
574 | =back |
732 | =back |
575 | |
733 | |
|
|
734 | Example: create a timer that fires after 60 seconds. |
|
|
735 | |
|
|
736 | static void |
|
|
737 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
738 | { |
|
|
739 | .. one minute over, w is actually stopped right here |
|
|
740 | } |
|
|
741 | |
|
|
742 | struct ev_timer mytimer; |
|
|
743 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
744 | ev_timer_start (loop, &mytimer); |
|
|
745 | |
|
|
746 | Example: create a timeout timer that times out after 10 seconds of |
|
|
747 | inactivity. |
|
|
748 | |
|
|
749 | static void |
|
|
750 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
751 | { |
|
|
752 | .. ten seconds without any activity |
|
|
753 | } |
|
|
754 | |
|
|
755 | struct ev_timer mytimer; |
|
|
756 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
757 | ev_timer_again (&mytimer); /* start timer */ |
|
|
758 | ev_loop (loop, 0); |
|
|
759 | |
|
|
760 | // and in some piece of code that gets executed on any "activity": |
|
|
761 | // reset the timeout to start ticking again at 10 seconds |
|
|
762 | ev_timer_again (&mytimer); |
|
|
763 | |
|
|
764 | |
576 | =head2 C<ev_periodic> - to cron or not to cron |
765 | =head2 C<ev_periodic> - to cron or not to cron |
577 | |
766 | |
578 | Periodic watchers are also timers of a kind, but they are very versatile |
767 | Periodic watchers are also timers of a kind, but they are very versatile |
579 | (and unfortunately a bit complex). |
768 | (and unfortunately a bit complex). |
580 | |
769 | |
… | |
… | |
675 | a different time than the last time it was called (e.g. in a crond like |
864 | a different time than the last time it was called (e.g. in a crond like |
676 | program when the crontabs have changed). |
865 | program when the crontabs have changed). |
677 | |
866 | |
678 | =back |
867 | =back |
679 | |
868 | |
|
|
869 | Example: call a callback every hour, or, more precisely, whenever the |
|
|
870 | system clock is divisible by 3600. The callback invocation times have |
|
|
871 | potentially a lot of jittering, but good long-term stability. |
|
|
872 | |
|
|
873 | static void |
|
|
874 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
875 | { |
|
|
876 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
877 | } |
|
|
878 | |
|
|
879 | struct ev_periodic hourly_tick; |
|
|
880 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
881 | ev_periodic_start (loop, &hourly_tick); |
|
|
882 | |
|
|
883 | Example: the same as above, but use a reschedule callback to do it: |
|
|
884 | |
|
|
885 | #include <math.h> |
|
|
886 | |
|
|
887 | static ev_tstamp |
|
|
888 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
889 | { |
|
|
890 | return fmod (now, 3600.) + 3600.; |
|
|
891 | } |
|
|
892 | |
|
|
893 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
894 | |
|
|
895 | Example: call a callback every hour, starting now: |
|
|
896 | |
|
|
897 | struct ev_periodic hourly_tick; |
|
|
898 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
899 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
900 | ev_periodic_start (loop, &hourly_tick); |
|
|
901 | |
|
|
902 | |
680 | =head2 C<ev_signal> - signal me when a signal gets signalled |
903 | =head2 C<ev_signal> - signal me when a signal gets signalled |
681 | |
904 | |
682 | Signal watchers will trigger an event when the process receives a specific |
905 | Signal watchers will trigger an event when the process receives a specific |
683 | signal one or more times. Even though signals are very asynchronous, libev |
906 | signal one or more times. Even though signals are very asynchronous, libev |
684 | will try it's best to deliver signals synchronously, i.e. as part of the |
907 | will try it's best to deliver signals synchronously, i.e. as part of the |
… | |
… | |
719 | the status word (use the macros from C<sys/wait.h> and see your systems |
942 | the status word (use the macros from C<sys/wait.h> and see your systems |
720 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
943 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
721 | process causing the status change. |
944 | process causing the status change. |
722 | |
945 | |
723 | =back |
946 | =back |
|
|
947 | |
|
|
948 | Example: try to exit cleanly on SIGINT and SIGTERM. |
|
|
949 | |
|
|
950 | static void |
|
|
951 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
952 | { |
|
|
953 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
954 | } |
|
|
955 | |
|
|
956 | struct ev_signal signal_watcher; |
|
|
957 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
958 | ev_signal_start (loop, &sigint_cb); |
|
|
959 | |
724 | |
960 | |
725 | =head2 C<ev_idle> - when you've got nothing better to do |
961 | =head2 C<ev_idle> - when you've got nothing better to do |
726 | |
962 | |
727 | Idle watchers trigger events when there are no other events are pending |
963 | Idle watchers trigger events when there are no other events are pending |
728 | (prepare, check and other idle watchers do not count). That is, as long |
964 | (prepare, check and other idle watchers do not count). That is, as long |
… | |
… | |
747 | Initialises and configures the idle watcher - it has no parameters of any |
983 | Initialises and configures the idle watcher - it has no parameters of any |
748 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
984 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
749 | believe me. |
985 | believe me. |
750 | |
986 | |
751 | =back |
987 | =back |
|
|
988 | |
|
|
989 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
|
|
990 | callback, free it. Alos, use no error checking, as usual. |
|
|
991 | |
|
|
992 | static void |
|
|
993 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
994 | { |
|
|
995 | free (w); |
|
|
996 | // now do something you wanted to do when the program has |
|
|
997 | // no longer asnything immediate to do. |
|
|
998 | } |
|
|
999 | |
|
|
1000 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1001 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1002 | ev_idle_start (loop, idle_cb); |
|
|
1003 | |
752 | |
1004 | |
753 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1005 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
754 | |
1006 | |
755 | Prepare and check watchers are usually (but not always) used in tandem: |
1007 | Prepare and check watchers are usually (but not always) used in tandem: |
756 | prepare watchers get invoked before the process blocks and check watchers |
1008 | prepare watchers get invoked before the process blocks and check watchers |
… | |
… | |
788 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1040 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
789 | macros, but using them is utterly, utterly and completely pointless. |
1041 | macros, but using them is utterly, utterly and completely pointless. |
790 | |
1042 | |
791 | =back |
1043 | =back |
792 | |
1044 | |
|
|
1045 | Example: *TODO*. |
|
|
1046 | |
|
|
1047 | |
793 | =head1 OTHER FUNCTIONS |
1048 | =head1 OTHER FUNCTIONS |
794 | |
1049 | |
795 | There are some other functions of possible interest. Described. Here. Now. |
1050 | There are some other functions of possible interest. Described. Here. Now. |
796 | |
1051 | |
797 | =over 4 |
1052 | =over 4 |
… | |
… | |
843 | |
1098 | |
844 | Feed an event as if the given signal occured (loop must be the default loop!). |
1099 | Feed an event as if the given signal occured (loop must be the default loop!). |
845 | |
1100 | |
846 | =back |
1101 | =back |
847 | |
1102 | |
|
|
1103 | |
848 | =head1 LIBEVENT EMULATION |
1104 | =head1 LIBEVENT EMULATION |
849 | |
1105 | |
850 | Libev offers a compatibility emulation layer for libevent. It cannot |
1106 | Libev offers a compatibility emulation layer for libevent. It cannot |
851 | emulate the internals of libevent, so here are some usage hints: |
1107 | emulate the internals of libevent, so here are some usage hints: |
852 | |
1108 | |