… | |
… | |
37 | # CHILD/PID STATUS CHANGES |
37 | # CHILD/PID STATUS CHANGES |
38 | |
38 | |
39 | my $w = EV::child 666, sub { |
39 | my $w = EV::child 666, sub { |
40 | my ($w, $revents) = @_; |
40 | my ($w, $revents) = @_; |
41 | my $status = $w->rstatus; |
41 | my $status = $w->rstatus; |
|
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42 | }; |
|
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43 | |
|
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44 | # STAT CHANGES |
|
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45 | my $w = EV::stat "/etc/passwd", 10, sub { |
|
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46 | my ($w, $revents) = @_; |
|
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47 | warn $w->path, " has changed somehow.\n"; |
42 | }; |
48 | }; |
43 | |
49 | |
44 | # MAINLOOP |
50 | # MAINLOOP |
45 | EV::loop; # loop until EV::unloop is called or all watchers stop |
51 | EV::loop; # loop until EV::unloop is called or all watchers stop |
46 | EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
52 | EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
47 | EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
53 | EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
48 | |
54 | |
49 | DESCRIPTION |
55 | DESCRIPTION |
50 | This module provides an interface to libev |
56 | This module provides an interface to libev |
51 | (<http://software.schmorp.de/pkg/libev.html>). |
57 | (<http://software.schmorp.de/pkg/libev.html>). While the documentation |
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58 | below is comprehensive, one might also consult the documentation of |
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59 | libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle |
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60 | details on watcher semantics or some discussion on the available |
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61 | backends, or how to force a specific backend with "LIBEV_FLAGS", or just |
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62 | about in any case because it has much more detailed information. |
52 | |
63 | |
53 | BASIC INTERFACE |
64 | BASIC INTERFACE |
54 | $EV::DIED |
65 | $EV::DIED |
55 | Must contain a reference to a function that is called when a |
66 | Must contain a reference to a function that is called when a |
56 | callback throws an exception (with $@ containing thr error). The |
67 | callback throws an exception (with $@ containing thr error). The |
… | |
… | |
85 | makes the innermost call to EV::loop return. |
96 | makes the innermost call to EV::loop return. |
86 | |
97 | |
87 | When called with an argument of EV::UNLOOP_ALL, all calls to |
98 | When called with an argument of EV::UNLOOP_ALL, all calls to |
88 | EV::loop will return as fast as possible. |
99 | EV::loop will return as fast as possible. |
89 | |
100 | |
90 | WATCHER |
101 | $count = EV::loop_count |
|
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102 | Return the number of times the event loop has polled for new events. |
|
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103 | Sometiems useful as a generation counter. |
|
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104 | |
|
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105 | EV::once $fh_or_undef, $events, $timeout, $cb->($revents) |
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106 | This function rolls together an I/O and a timer watcher for a single |
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107 | one-shot event without the need for managing a watcher object. |
|
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108 | |
|
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109 | If $fh_or_undef is a filehandle or file descriptor, then $events |
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110 | must be a bitset containing either "EV::READ", "EV::WRITE" or |
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111 | "EV::READ | EV::WRITE", indicating the type of I/O event you want to |
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112 | wait for. If you do not want to wait for some I/O event, specify |
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113 | "undef" for $fh_or_undef and 0 for $events). |
|
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114 | |
|
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115 | If timeout is "undef" or negative, then there will be no timeout. |
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116 | Otherwise a EV::timer with this value will be started. |
|
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117 | |
|
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118 | When an error occurs or either the timeout or I/O watcher triggers, |
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119 | then the callback will be called with the received event set (in |
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120 | general you can expect it to be a combination of "EV:ERROR", |
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121 | "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). |
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122 | |
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123 | EV::once doesn't return anything: the watchers stay active till |
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124 | either of them triggers, then they will be stopped and freed, and |
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125 | the callback invoked. |
|
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126 | |
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127 | WATCHER OBJECTS |
91 | A watcher is an object that gets created to record your interest in some |
128 | A watcher is an object that gets created to record your interest in some |
92 | event. For instance, if you want to wait for STDIN to become readable, |
129 | event. For instance, if you want to wait for STDIN to become readable, |
93 | you would create an EV::io watcher for that: |
130 | you would create an EV::io watcher for that: |
94 | |
131 | |
95 | my $watcher = EV::io *STDIN, EV::READ, sub { |
132 | my $watcher = EV::io *STDIN, EV::READ, sub { |
… | |
… | |
103 | received events. |
140 | received events. |
104 | |
141 | |
105 | Each watcher type has its associated bit in revents, so you can use the |
142 | Each watcher type has its associated bit in revents, so you can use the |
106 | same callback for multiple watchers. The event mask is named after the |
143 | same callback for multiple watchers. The event mask is named after the |
107 | type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
144 | type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
108 | EV::periodic sets EV::PERIODIC and so on, with the exception of IO |
145 | EV::periodic sets EV::PERIODIC and so on, with the exception of I/O |
109 | events (which can set both EV::READ and EV::WRITE bits), and EV::timer |
146 | events (which can set both EV::READ and EV::WRITE bits), and EV::timer |
110 | (which uses EV::TIMEOUT). |
147 | (which uses EV::TIMEOUT). |
111 | |
148 | |
112 | In the rare case where one wants to create a watcher but not start it at |
149 | In the rare case where one wants to create a watcher but not start it at |
113 | the same time, each constructor has a variant with a trailing "_ns" in |
150 | the same time, each constructor has a variant with a trailing "_ns" in |
… | |
… | |
119 | |
156 | |
120 | Also, all methods changing some aspect of a watcher (->set, ->priority, |
157 | Also, all methods changing some aspect of a watcher (->set, ->priority, |
121 | ->fh and so on) automatically stop and start it again if it is active, |
158 | ->fh and so on) automatically stop and start it again if it is active, |
122 | which means pending events get lost. |
159 | which means pending events get lost. |
123 | |
160 | |
124 | WATCHER TYPES |
161 | COMMON WATCHER METHODS |
125 | Now lets move to the existing watcher types and asociated methods. |
162 | This section lists methods common to all watchers. |
126 | |
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127 | The following methods are available for all watchers. Then followes a |
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128 | description of each watcher constructor (EV::io, EV::timer, |
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129 | EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and |
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130 | EV::check), followed by any type-specific methods (if any). |
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131 | |
163 | |
132 | $w->start |
164 | $w->start |
133 | Starts a watcher if it isn't active already. Does nothing to an |
165 | Starts a watcher if it isn't active already. Does nothing to an |
134 | already active watcher. By default, all watchers start out in the |
166 | already active watcher. By default, all watchers start out in the |
135 | active state (see the description of the "_ns" variants if you need |
167 | active state (see the description of the "_ns" variants if you need |
136 | stopped watchers). |
168 | stopped watchers). |
137 | |
169 | |
138 | $w->stop |
170 | $w->stop |
139 | Stop a watcher if it is active. Also clear any pending events |
171 | Stop a watcher if it is active. Also clear any pending events |
140 | (events that have been received but that didn't yet result in a |
172 | (events that have been received but that didn't yet result in a |
141 | callback invocation), regardless of wether the watcher was active or |
173 | callback invocation), regardless of whether the watcher was active |
142 | not. |
174 | or not. |
143 | |
175 | |
144 | $bool = $w->is_active |
176 | $bool = $w->is_active |
145 | Returns true if the watcher is active, false otherwise. |
177 | Returns true if the watcher is active, false otherwise. |
146 | |
178 | |
147 | $current_data = $w->data |
179 | $current_data = $w->data |
… | |
… | |
165 | Pending watchers with higher priority will be invoked first. The |
197 | Pending watchers with higher priority will be invoked first. The |
166 | valid range of priorities lies between EV::MAXPRI (default 2) and |
198 | valid range of priorities lies between EV::MAXPRI (default 2) and |
167 | EV::MINPRI (default -2). If the priority is outside this range it |
199 | EV::MINPRI (default -2). If the priority is outside this range it |
168 | will automatically be normalised to the nearest valid priority. |
200 | will automatically be normalised to the nearest valid priority. |
169 | |
201 | |
170 | The default priority of any newly-created weatcher is 0. |
202 | The default priority of any newly-created watcher is 0. |
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203 | |
|
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204 | Note that the priority semantics have not yet been fleshed out and |
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205 | are subject to almost certain change. |
171 | |
206 | |
172 | $w->trigger ($revents) |
207 | $w->trigger ($revents) |
173 | Call the callback *now* with the given event mask. |
208 | Call the callback *now* with the given event mask. |
174 | |
209 | |
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210 | $previous_state = $w->keepalive ($bool) |
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211 | Normally, "EV::loop" will return when there are no active watchers |
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212 | (which is a "deadlock" because no progress can be made anymore). |
|
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213 | This is convinient because it allows you to start your watchers (and |
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214 | your jobs), call "EV::loop" once and when it returns you know that |
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215 | all your jobs are finished (or they forgot to register some watchers |
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216 | for their task :). |
|
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217 | |
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218 | Sometimes, however, this gets in your way, for example when you the |
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219 | module that calls "EV::loop" (usually the main program) is not the |
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220 | same module as a long-living watcher (for example a DNS client |
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221 | module written by somebody else even). Then you might want any |
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222 | outstanding requests to be handled, but you would not want to keep |
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223 | "EV::loop" from returning just because you happen to have this |
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224 | long-running UDP port watcher. |
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225 | |
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226 | In this case you can clear the keepalive status, which means that |
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227 | even though your watcher is active, it won't keep "EV::loop" from |
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228 | returning. |
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229 | |
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230 | The initial value for keepalive is true (enabled), and you cna |
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231 | change it any time. |
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232 | |
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233 | Example: Register an I/O watcher for some UDP socket but do not keep |
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234 | the event loop from running just because of that watcher. |
|
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235 | |
|
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236 | my $udp_socket = ... |
|
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237 | my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; |
|
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238 | $udp_watcher->keepalive (0); |
|
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239 | |
|
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240 | WATCHER TYPES |
|
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241 | Each of the following subsections describes a single watcher type. |
|
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242 | |
|
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243 | I/O WATCHERS - is this file descriptor readable or writable? |
175 | $w = EV::io $fileno_or_fh, $eventmask, $callback |
244 | $w = EV::io $fileno_or_fh, $eventmask, $callback |
176 | $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
245 | $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
177 | As long as the returned watcher object is alive, call the $callback |
246 | As long as the returned watcher object is alive, call the $callback |
178 | when the events specified in $eventmask. |
247 | when at least one of events specified in $eventmask occurs. |
179 | |
248 | |
180 | The $eventmask can be one or more of these constants ORed together: |
249 | The $eventmask can be one or more of these constants ORed together: |
181 | |
250 | |
182 | EV::READ wait until read() wouldn't block anymore |
251 | EV::READ wait until read() wouldn't block anymore |
183 | EV::WRITE wait until write() wouldn't block anymore |
252 | EV::WRITE wait until write() wouldn't block anymore |
… | |
… | |
195 | |
264 | |
196 | $current_eventmask = $w->events |
265 | $current_eventmask = $w->events |
197 | $old_eventmask = $w->events ($new_eventmask) |
266 | $old_eventmask = $w->events ($new_eventmask) |
198 | Returns the previously set event mask and optionally set a new one. |
267 | Returns the previously set event mask and optionally set a new one. |
199 | |
268 | |
|
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269 | TIMER WATCHERS - relative and optionally repeating timeouts |
200 | $w = EV::timer $after, $repeat, $callback |
270 | $w = EV::timer $after, $repeat, $callback |
201 | $w = EV::timer_ns $after, $repeat, $callback |
271 | $w = EV::timer_ns $after, $repeat, $callback |
202 | Calls the callback after $after seconds. If $repeat is non-zero, the |
272 | Calls the callback after $after seconds (which may be fractional). |
203 | timer will be restarted (with the $repeat value as $after) after the |
273 | If $repeat is non-zero, the timer will be restarted (with the |
204 | callback returns. |
274 | $repeat value as $after) after the callback returns. |
205 | |
275 | |
206 | This means that the callback would be called roughly after $after |
276 | This means that the callback would be called roughly after $after |
207 | seconds, and then every $repeat seconds. The timer does his best not |
277 | seconds, and then every $repeat seconds. The timer does his best not |
208 | to drift, but it will not invoke the timer more often then once per |
278 | to drift, but it will not invoke the timer more often then once per |
209 | event loop iteration, and might drift in other cases. If that isn't |
279 | event loop iteration, and might drift in other cases. If that isn't |
… | |
… | |
218 | The "timer_ns" variant doesn't start (activate) the newly created |
288 | The "timer_ns" variant doesn't start (activate) the newly created |
219 | watcher. |
289 | watcher. |
220 | |
290 | |
221 | $w->set ($after, $repeat) |
291 | $w->set ($after, $repeat) |
222 | Reconfigures the watcher, see the constructor above for details. Can |
292 | Reconfigures the watcher, see the constructor above for details. Can |
223 | be at any time. |
293 | be called at any time. |
224 | |
294 | |
225 | $w->again |
295 | $w->again |
226 | Similar to the "start" method, but has special semantics for |
296 | Similar to the "start" method, but has special semantics for |
227 | repeating timers: |
297 | repeating timers: |
228 | |
298 | |
… | |
… | |
239 | This behaviour is useful when you have a timeout for some IO |
309 | This behaviour is useful when you have a timeout for some IO |
240 | operation. You create a timer object with the same value for $after |
310 | operation. You create a timer object with the same value for $after |
241 | and $repeat, and then, in the read/write watcher, run the "again" |
311 | and $repeat, and then, in the read/write watcher, run the "again" |
242 | method on the timeout. |
312 | method on the timeout. |
243 | |
313 | |
|
|
314 | PERIODIC WATCHERS - to cron or not to cron? |
244 | $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
315 | $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
245 | $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
316 | $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
246 | Similar to EV::timer, but is not based on relative timeouts but on |
317 | Similar to EV::timer, but is not based on relative timeouts but on |
247 | absolute times. Apart from creating "simple" timers that trigger |
318 | absolute times. Apart from creating "simple" timers that trigger |
248 | "at" the specified time, it can also be used for non-drifting |
319 | "at" the specified time, it can also be used for non-drifting |
… | |
… | |
313 | The "periodic_ns" variant doesn't start (activate) the newly created |
384 | The "periodic_ns" variant doesn't start (activate) the newly created |
314 | watcher. |
385 | watcher. |
315 | |
386 | |
316 | $w->set ($at, $interval, $reschedule_cb) |
387 | $w->set ($at, $interval, $reschedule_cb) |
317 | Reconfigures the watcher, see the constructor above for details. Can |
388 | Reconfigures the watcher, see the constructor above for details. Can |
318 | be at any time. |
389 | be called at any time. |
319 | |
390 | |
320 | $w->again |
391 | $w->again |
321 | Simply stops and starts the watcher again. |
392 | Simply stops and starts the watcher again. |
322 | |
393 | |
|
|
394 | SIGNAL WATCHERS - signal me when a signal gets signalled! |
323 | $w = EV::signal $signal, $callback |
395 | $w = EV::signal $signal, $callback |
324 | $w = EV::signal_ns $signal, $callback |
396 | $w = EV::signal_ns $signal, $callback |
325 | Call the callback when $signal is received (the signal can be |
397 | Call the callback when $signal is received (the signal can be |
326 | specified by number or by name, just as with kill or %SIG). |
398 | specified by number or by name, just as with "kill" or %SIG). |
327 | |
399 | |
328 | EV will grab the signal for the process (the kernel only allows one |
400 | EV will grab the signal for the process (the kernel only allows one |
329 | component to receive a signal at a time) when you start a signal |
401 | component to receive a signal at a time) when you start a signal |
330 | watcher, and removes it again when you stop it. Perl does the same |
402 | watcher, and removes it again when you stop it. Perl does the same |
331 | when you add/remove callbacks to %SIG, so watch out. |
403 | when you add/remove callbacks to %SIG, so watch out. |
… | |
… | |
335 | The "signal_ns" variant doesn't start (activate) the newly created |
407 | The "signal_ns" variant doesn't start (activate) the newly created |
336 | watcher. |
408 | watcher. |
337 | |
409 | |
338 | $w->set ($signal) |
410 | $w->set ($signal) |
339 | Reconfigures the watcher, see the constructor above for details. Can |
411 | Reconfigures the watcher, see the constructor above for details. Can |
340 | be at any time. |
412 | be called at any time. |
341 | |
413 | |
342 | $current_signum = $w->signal |
414 | $current_signum = $w->signal |
343 | $old_signum = $w->signal ($new_signal) |
415 | $old_signum = $w->signal ($new_signal) |
344 | Returns the previously set signal (always as a number not name) and |
416 | Returns the previously set signal (always as a number not name) and |
345 | optionally set a new one. |
417 | optionally set a new one. |
346 | |
418 | |
|
|
419 | CHILD WATCHERS - watch out for process status changes |
347 | $w = EV::child $pid, $callback |
420 | $w = EV::child $pid, $callback |
348 | $w = EV::child_ns $pid, $callback |
421 | $w = EV::child_ns $pid, $callback |
349 | Call the callback when a status change for pid $pid (or any pid if |
422 | Call the callback when a status change for pid $pid (or any pid if |
350 | $pid is 0) has been received. More precisely: when the process |
423 | $pid is 0) has been received. More precisely: when the process |
351 | receives a SIGCHLD, EV will fetch the outstanding exit/wait status |
424 | receives a "SIGCHLD", EV will fetch the outstanding exit/wait status |
352 | for all changed/zombie children and call the callback. |
425 | for all changed/zombie children and call the callback. |
353 | |
426 | |
354 | You can access both status and pid by using the "rstatus" and "rpid" |
427 | It is valid (and fully supported) to install a child watcher after a |
|
|
428 | child has exited but before the event loop has started its next |
|
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429 | iteration (for example, first you "fork", then the new child process |
|
|
430 | might exit, and only then do you install a child watcher in the |
|
|
431 | parent for the new pid). |
|
|
432 | |
|
|
433 | You can access both exit (or tracing) status and pid by using the |
355 | methods on the watcher object. |
434 | "rstatus" and "rpid" methods on the watcher object. |
356 | |
435 | |
357 | You can have as many pid watchers per pid as you want. |
436 | You can have as many pid watchers per pid as you want, they will all |
|
|
437 | be called. |
358 | |
438 | |
359 | The "child_ns" variant doesn't start (activate) the newly created |
439 | The "child_ns" variant doesn't start (activate) the newly created |
360 | watcher. |
440 | watcher. |
361 | |
441 | |
362 | $w->set ($pid) |
442 | $w->set ($pid) |
363 | Reconfigures the watcher, see the constructor above for details. Can |
443 | Reconfigures the watcher, see the constructor above for details. Can |
364 | be at any time. |
444 | be called at any time. |
365 | |
445 | |
366 | $current_pid = $w->pid |
446 | $current_pid = $w->pid |
367 | $old_pid = $w->pid ($new_pid) |
447 | $old_pid = $w->pid ($new_pid) |
368 | Returns the previously set process id and optionally set a new one. |
448 | Returns the previously set process id and optionally set a new one. |
369 | |
449 | |
… | |
… | |
373 | |
453 | |
374 | $pid = $w->rpid |
454 | $pid = $w->rpid |
375 | Return the pid of the awaited child (useful when you have installed |
455 | Return the pid of the awaited child (useful when you have installed |
376 | a watcher for all pids). |
456 | a watcher for all pids). |
377 | |
457 | |
|
|
458 | STAT WATCHERS - did the file attributes just change? |
|
|
459 | $w = EV::stat $path, $interval, $callback |
|
|
460 | $w = EV::stat_ns $path, $interval, $callback |
|
|
461 | Call the callback when a file status change has been detected on |
|
|
462 | $path. The $path does not need to exist, changing from "path exists" |
|
|
463 | to "path does not exist" is a status change like any other. |
|
|
464 | |
|
|
465 | The $interval is a recommended polling interval for systems where |
|
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466 | OS-supported change notifications don't exist or are not supported. |
|
|
467 | If you use 0 then an unspecified default is used (which is highly |
|
|
468 | recommended!), which is to be expected to be around five seconds |
|
|
469 | usually. |
|
|
470 | |
|
|
471 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
472 | as even with OS-supported change notifications, this can be |
|
|
473 | resource-intensive. |
|
|
474 | |
|
|
475 | The "stat_ns" variant doesn't start (activate) the newly created |
|
|
476 | watcher. |
|
|
477 | |
|
|
478 | ... = $w->stat |
|
|
479 | This call is very similar to the perl "stat" built-in: It stats |
|
|
480 | (using "lstat") the path specified in the watcher and sets perls |
|
|
481 | stat cache (as well as EV's idea of the current stat values) to the |
|
|
482 | values found. |
|
|
483 | |
|
|
484 | In scalar context, a boolean is return indicating success or failure |
|
|
485 | of the stat. In list context, the same 13-value list as with stat is |
|
|
486 | returned (except that the blksize and blocks fields are not |
|
|
487 | reliable). |
|
|
488 | |
|
|
489 | In the case of an error, errno is set to "ENOENT" (regardless of the |
|
|
490 | actual error value) and the "nlink" value is forced to zero (if the |
|
|
491 | stat was successful then nlink is guaranteed to be non-zero). |
|
|
492 | |
|
|
493 | See also the next two entries for more info. |
|
|
494 | |
|
|
495 | ... = $w->attr |
|
|
496 | Just like "$w->stat", but without the initial stat'ing: this returns |
|
|
497 | the values most recently detected by EV. See the next entry for more |
|
|
498 | info. |
|
|
499 | |
|
|
500 | ... = $w->prev |
|
|
501 | Just like "$w->stat", but without the initial stat'ing: this returns |
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502 | the previous set of values, before the change. |
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503 | |
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504 | That is, when the watcher callback is invoked, "$w->prev" will be |
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505 | set to the values found *before* a change was detected, while |
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506 | "$w->attr" returns the values found leading to the change detection. |
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507 | The difference (if any) between "prev" and "attr" is what triggered |
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508 | the callback. |
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509 | |
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510 | If you did something to the filesystem object and do not want to |
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511 | trigger yet another change, you can call "stat" to update EV's idea |
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512 | of what the current attributes are. |
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513 | |
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514 | $w->set ($path, $interval) |
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515 | Reconfigures the watcher, see the constructor above for details. Can |
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516 | be called at any time. |
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517 | |
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518 | $current_path = $w->path |
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519 | $old_path = $w->path ($new_path) |
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520 | Returns the previously set path and optionally set a new one. |
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521 | |
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522 | $current_interval = $w->interval |
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523 | $old_interval = $w->interval ($new_interval) |
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524 | Returns the previously set interval and optionally set a new one. |
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525 | Can be used to query the actual interval used. |
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526 | |
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527 | IDLE WATCHERS - when you've got nothing better to do... |
378 | $w = EV::idle $callback |
528 | $w = EV::idle $callback |
379 | $w = EV::idle_ns $callback |
529 | $w = EV::idle_ns $callback |
380 | Call the callback when there are no pending io, timer/periodic, |
530 | Call the callback when there are no other pending watchers of the |
381 | signal or child events, i.e. when the process is idle. |
531 | same or higher priority (excluding check, prepare and other idle |
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532 | watchers of the same or lower priority, of course). They are called |
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533 | idle watchers because when the watcher is the highest priority |
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534 | pending event in the process, the process is considered to be idle |
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535 | at that priority. |
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536 | |
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537 | If you want a watcher that is only ever called when *no* other |
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538 | events are outstanding you have to set the priority to "EV::MINPRI". |
382 | |
539 | |
383 | The process will not block as long as any idle watchers are active, |
540 | The process will not block as long as any idle watchers are active, |
384 | and they will be called repeatedly until stopped. |
541 | and they will be called repeatedly until stopped. |
385 | |
542 | |
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543 | For example, if you have idle watchers at priority 0 and 1, and an |
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544 | I/O watcher at priority 0, then the idle watcher at priority 1 and |
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545 | the I/O watcher will always run when ready. Only when the idle |
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546 | watcher at priority 1 is stopped and the I/O watcher at priority 0 |
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547 | is not pending with the 0-priority idle watcher be invoked. |
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548 | |
386 | The "idle_ns" variant doesn't start (activate) the newly created |
549 | The "idle_ns" variant doesn't start (activate) the newly created |
387 | watcher. |
550 | watcher. |
388 | |
551 | |
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552 | PREPARE WATCHERS - customise your event loop! |
389 | $w = EV::prepare $callback |
553 | $w = EV::prepare $callback |
390 | $w = EV::prepare_ns $callback |
554 | $w = EV::prepare_ns $callback |
391 | Call the callback just before the process would block. You can still |
555 | Call the callback just before the process would block. You can still |
392 | create/modify any watchers at this point. |
556 | create/modify any watchers at this point. |
393 | |
557 | |
394 | See the EV::check watcher, below, for explanations and an example. |
558 | See the EV::check watcher, below, for explanations and an example. |
395 | |
559 | |
396 | The "prepare_ns" variant doesn't start (activate) the newly created |
560 | The "prepare_ns" variant doesn't start (activate) the newly created |
397 | watcher. |
561 | watcher. |
398 | |
562 | |
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563 | CHECK WATCHERS - customise your event loop even more! |
399 | $w = EV::check $callback |
564 | $w = EV::check $callback |
400 | $w = EV::check_ns $callback |
565 | $w = EV::check_ns $callback |
401 | Call the callback just after the process wakes up again (after it |
566 | Call the callback just after the process wakes up again (after it |
402 | has gathered events), but before any other callbacks have been |
567 | has gathered events), but before any other callbacks have been |
403 | invoked. |
568 | invoked. |
… | |
… | |
414 | # do nothing unless active |
579 | # do nothing unless active |
415 | $dispatcher->{_event_queue_h} |
580 | $dispatcher->{_event_queue_h} |
416 | or return; |
581 | or return; |
417 | |
582 | |
418 | # make the dispatcher handle any outstanding stuff |
583 | # make the dispatcher handle any outstanding stuff |
|
|
584 | ... not shown |
419 | |
585 | |
420 | # create an IO watcher for each and every socket |
586 | # create an I/O watcher for each and every socket |
421 | @snmp_watcher = ( |
587 | @snmp_watcher = ( |
422 | (map { EV::io $_, EV::READ, sub { } } |
588 | (map { EV::io $_, EV::READ, sub { } } |
423 | keys %{ $dispatcher->{_descriptors} }), |
589 | keys %{ $dispatcher->{_descriptors} }), |
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590 | |
|
|
591 | EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] |
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592 | ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0), |
|
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593 | 0, sub { }, |
424 | ); |
594 | ); |
425 | |
|
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426 | # if there are any timeouts, also create a timer |
|
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427 | push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { } |
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428 | if $event->[Net::SNMP::Dispatcher::_ACTIVE]; |
|
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429 | }; |
595 | }; |
430 | |
596 | |
431 | The callbacks are irrelevant, the only purpose of those watchers is |
597 | The callbacks are irrelevant (and are not even being called), the |
432 | to wake up the process as soon as one of those events occurs (socket |
598 | only purpose of those watchers is to wake up the process as soon as |
433 | readable, or timer timed out). The corresponding EV::check watcher |
599 | one of those events occurs (socket readable, or timer timed out). |
434 | will then clean up: |
600 | The corresponding EV::check watcher will then clean up: |
435 | |
601 | |
436 | our $snmp_check = EV::check sub { |
602 | our $snmp_check = EV::check sub { |
437 | # destroy all watchers |
603 | # destroy all watchers |
438 | @snmp_watcher = (); |
604 | @snmp_watcher = (); |
439 | |
605 | |
440 | # make the dispatcher handle any new stuff |
606 | # make the dispatcher handle any new stuff |
|
|
607 | ... not shown |
441 | }; |
608 | }; |
442 | |
609 | |
443 | The callbacks of the created watchers will not be called as the |
610 | The callbacks of the created watchers will not be called as the |
444 | watchers are destroyed before this cna happen (remember EV::check |
611 | watchers are destroyed before this cna happen (remember EV::check |
445 | gets called first). |
612 | gets called first). |
446 | |
613 | |
447 | The "check_ns" variant doesn't start (activate) the newly created |
614 | The "check_ns" variant doesn't start (activate) the newly created |
448 | watcher. |
615 | watcher. |
449 | |
616 | |
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|
617 | FORK WATCHERS - the audacity to resume the event loop after a fork |
|
|
618 | Fork watchers are called when a "fork ()" was detected. The invocation |
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619 | is done before the event loop blocks next and before "check" watchers |
|
|
620 | are being called, and only in the child after the fork. |
|
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621 | |
|
|
622 | $w = EV::fork $callback |
|
|
623 | $w = EV::fork_ns $callback |
|
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624 | Call the callback before the event loop is resumed in the child |
|
|
625 | process after a fork. |
|
|
626 | |
|
|
627 | The "fork_ns" variant doesn't start (activate) the newly created |
|
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628 | watcher. |
|
|
629 | |
|
|
630 | PERL SIGNALS |
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|
631 | While Perl signal handling (%SIG) is not affected by EV, the behaviour |
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632 | with EV is as the same as any other C library: Perl-signals will only be |
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633 | handled when Perl runs, which means your signal handler might be invoked |
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634 | only the next time an event callback is invoked. |
|
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635 | |
|
|
636 | The solution is to use EV signal watchers (see "EV::signal"), which will |
|
|
637 | ensure proper operations with regards to other event watchers. |
|
|
638 | |
|
|
639 | If you cannot do this for whatever reason, you can also force a watcher |
|
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640 | to be called on every event loop iteration by installing a "EV::check" |
|
|
641 | watcher: |
|
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642 | |
|
|
643 | my $async_check = EV::check sub { }; |
|
|
644 | |
|
|
645 | This ensures that perl shortly gets into control for a short time, and |
|
|
646 | also ensures slower overall operation. |
|
|
647 | |
450 | THREADS |
648 | THREADS |
451 | Threads are not supported by this in any way. Perl pseudo-threads is |
649 | Threads are not supported by this module in any way. Perl pseudo-threads |
452 | evil stuff and must die. |
650 | is evil stuff and must die. As soon as Perl gains real threads I will |
|
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651 | work on thread support for it. |
|
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652 | |
|
|
653 | FORK |
|
|
654 | Most of the "improved" event delivering mechanisms of modern operating |
|
|
655 | systems have quite a few problems with fork(2) (to put it bluntly: it is |
|
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656 | not supported and usually destructive). Libev makes it possible to work |
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657 | around this by having a function that recreates the kernel state after |
|
|
658 | fork in the child. |
|
|
659 | |
|
|
660 | On non-win32 platforms, this module requires the pthread_atfork |
|
|
661 | functionality to do this automatically for you. This function is quite |
|
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662 | buggy on most BSDs, though, so YMMV. The overhead for this is quite |
|
|
663 | negligible, because everything the function currently does is set a flag |
|
|
664 | that is checked only when the event loop gets used the next time, so |
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|
665 | when you do fork but not use EV, the overhead is minimal. |
|
|
666 | |
|
|
667 | On win32, there is no notion of fork so all this doesn't apply, of |
|
|
668 | course. |
453 | |
669 | |
454 | SEE ALSO |
670 | SEE ALSO |
455 | L<EV::DNS>. |
671 | EV::ADNS (asynchronous dns), Glib::EV (makes Glib/Gtk2 use EV as event |
|
|
672 | loop), Coro::EV (efficient coroutines with EV). |
456 | |
673 | |
457 | AUTHOR |
674 | AUTHOR |
458 | Marc Lehmann <schmorp@schmorp.de> |
675 | Marc Lehmann <schmorp@schmorp.de> |
459 | http://home.schmorp.de/ |
676 | http://home.schmorp.de/ |
460 | |
677 | |