1 | => NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - provide framework for multiple event loops |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
5 | loops |
5 | event loops. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
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10 | # file descriptor readable |
10 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
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12 | |
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13 | # one-shot or repeating timers |
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14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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16 | |
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17 | print AnyEvent->now; # prints current event loop time |
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18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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19 | |
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20 | # POSIX signal |
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21 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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22 | |
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23 | # child process exit |
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24 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
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25 | my ($pid, $status) = @_; |
11 | ... |
26 | ... |
12 | }); |
27 | }); |
13 | |
28 | |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
29 | # called when event loop idle (if applicable) |
15 | ... |
30 | my $w = AnyEvent->idle (cb => sub { ... }); |
16 | }); |
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17 | |
31 | |
18 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
32 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
19 | $w->send; # wake up current and all future recv's |
33 | $w->send; # wake up current and all future recv's |
20 | $w->recv; # enters "main loop" till $condvar gets ->send |
34 | $w->recv; # enters "main loop" till $condvar gets ->send |
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35 | # use a condvar in callback mode: |
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36 | $w->cb (sub { $_[0]->recv }); |
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37 | |
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38 | INTRODUCTION/TUTORIAL |
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39 | This manpage is mainly a reference manual. If you are interested in a |
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40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
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41 | manpage. |
21 | |
42 | |
22 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
43 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
23 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
44 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
24 | nowadays. So what is different about AnyEvent? |
45 | nowadays. So what is different about AnyEvent? |
25 | |
46 | |
26 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
47 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
27 | policy* and AnyEvent is *small and efficient*. |
48 | policy* and AnyEvent is *small and efficient*. |
28 | |
49 | |
29 | First and foremost, *AnyEvent is not an event model* itself, it only |
50 | First and foremost, *AnyEvent is not an event model* itself, it only |
30 | interfaces to whatever event model the main program happens to use in a |
51 | interfaces to whatever event model the main program happens to use, in a |
31 | pragmatic way. For event models and certain classes of immortals alike, |
52 | pragmatic way. For event models and certain classes of immortals alike, |
32 | the statement "there can only be one" is a bitter reality: In general, |
53 | the statement "there can only be one" is a bitter reality: In general, |
33 | only one event loop can be active at the same time in a process. |
54 | only one event loop can be active at the same time in a process. |
34 | AnyEvent helps hiding the differences between those event loops. |
55 | AnyEvent cannot change this, but it can hide the differences between |
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56 | those event loops. |
35 | |
57 | |
36 | The goal of AnyEvent is to offer module authors the ability to do event |
58 | The goal of AnyEvent is to offer module authors the ability to do event |
37 | programming (waiting for I/O or timer events) without subscribing to a |
59 | programming (waiting for I/O or timer events) without subscribing to a |
38 | religion, a way of living, and most importantly: without forcing your |
60 | religion, a way of living, and most importantly: without forcing your |
39 | module users into the same thing by forcing them to use the same event |
61 | module users into the same thing by forcing them to use the same event |
40 | model you use. |
62 | model you use. |
41 | |
63 | |
42 | For modules like POE or IO::Async (which is a total misnomer as it is |
64 | For modules like POE or IO::Async (which is a total misnomer as it is |
43 | actually doing all I/O *synchronously*...), using them in your module is |
65 | actually doing all I/O *synchronously*...), using them in your module is |
44 | like joining a cult: After you joined, you are dependent on them and you |
66 | like joining a cult: After you joined, you are dependent on them and you |
45 | cannot use anything else, as it is simply incompatible to everything |
67 | cannot use anything else, as they are simply incompatible to everything |
46 | that isn't itself. What's worse, all the potential users of your module |
68 | that isn't them. What's worse, all the potential users of your module |
47 | are *also* forced to use the same event loop you use. |
69 | are *also* forced to use the same event loop you use. |
48 | |
70 | |
49 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
71 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
50 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
72 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
51 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
73 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
52 | module uses one of those, every user of your module has to use it, too. |
74 | module uses one of those, every user of your module has to use it, too. |
53 | But if your module uses AnyEvent, it works transparently with all event |
75 | But if your module uses AnyEvent, it works transparently with all event |
54 | models it supports (including stuff like POE and IO::Async, as long as |
76 | models it supports (including stuff like IO::Async, as long as those use |
55 | those use one of the supported event loops. It is trivial to add new |
77 | one of the supported event loops. It is trivial to add new event loops |
56 | event loops to AnyEvent, too, so it is future-proof). |
78 | to AnyEvent, too, so it is future-proof). |
57 | |
79 | |
58 | In addition to being free of having to use *the one and only true event |
80 | In addition to being free of having to use *the one and only true event |
59 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
81 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
60 | modules, you get an enormous amount of code and strict rules you have to |
82 | modules, you get an enormous amount of code and strict rules you have to |
61 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
83 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
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117 | These watchers are normal Perl objects with normal Perl lifetime. After |
139 | These watchers are normal Perl objects with normal Perl lifetime. After |
118 | creating a watcher it will immediately "watch" for events and invoke the |
140 | creating a watcher it will immediately "watch" for events and invoke the |
119 | callback when the event occurs (of course, only when the event model is |
141 | callback when the event occurs (of course, only when the event model is |
120 | in control). |
142 | in control). |
121 | |
143 | |
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144 | Note that callbacks must not permanently change global variables |
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145 | potentially in use by the event loop (such as $_ or $[) and that |
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146 | callbacks must not "die". The former is good programming practise in |
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147 | Perl and the latter stems from the fact that exception handling differs |
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148 | widely between event loops. |
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149 | |
122 | To disable the watcher you have to destroy it (e.g. by setting the |
150 | To disable the watcher you have to destroy it (e.g. by setting the |
123 | variable you store it in to "undef" or otherwise deleting all references |
151 | variable you store it in to "undef" or otherwise deleting all references |
124 | to it). |
152 | to it). |
125 | |
153 | |
126 | All watchers are created by calling a method on the "AnyEvent" class. |
154 | All watchers are created by calling a method on the "AnyEvent" class. |
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128 | Many watchers either are used with "recursion" (repeating timers for |
156 | Many watchers either are used with "recursion" (repeating timers for |
129 | example), or need to refer to their watcher object in other ways. |
157 | example), or need to refer to their watcher object in other ways. |
130 | |
158 | |
131 | An any way to achieve that is this pattern: |
159 | An any way to achieve that is this pattern: |
132 | |
160 | |
133 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
161 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
134 | # you can use $w here, for example to undef it |
162 | # you can use $w here, for example to undef it |
135 | undef $w; |
163 | undef $w; |
136 | }); |
164 | }); |
137 | |
165 | |
138 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
166 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
139 | my variables are only visible after the statement in which they are |
167 | my variables are only visible after the statement in which they are |
140 | declared. |
168 | declared. |
141 | |
169 | |
142 | I/O WATCHERS |
170 | I/O WATCHERS |
143 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
171 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
144 | the following mandatory key-value pairs as arguments: |
172 | the following mandatory key-value pairs as arguments: |
145 | |
173 | |
146 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events. |
174 | "fh" is the Perl *file handle* (*not* file descriptor) to watch for |
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175 | events (AnyEvent might or might not keep a reference to this file |
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176 | handle). Note that only file handles pointing to things for which |
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177 | non-blocking operation makes sense are allowed. This includes sockets, |
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178 | most character devices, pipes, fifos and so on, but not for example |
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179 | files or block devices. |
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180 | |
147 | "poll" must be a string that is either "r" or "w", which creates a |
181 | "poll" must be a string that is either "r" or "w", which creates a |
148 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
182 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
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183 | |
149 | is the callback to invoke each time the file handle becomes ready. |
184 | "cb" is the callback to invoke each time the file handle becomes ready. |
150 | |
185 | |
151 | Although the callback might get passed parameters, their value and |
186 | Although the callback might get passed parameters, their value and |
152 | presence is undefined and you cannot rely on them. Portable AnyEvent |
187 | presence is undefined and you cannot rely on them. Portable AnyEvent |
153 | callbacks cannot use arguments passed to I/O watcher callbacks. |
188 | callbacks cannot use arguments passed to I/O watcher callbacks. |
154 | |
189 | |
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158 | |
193 | |
159 | Some event loops issue spurious readyness notifications, so you should |
194 | Some event loops issue spurious readyness notifications, so you should |
160 | always use non-blocking calls when reading/writing from/to your file |
195 | always use non-blocking calls when reading/writing from/to your file |
161 | handles. |
196 | handles. |
162 | |
197 | |
163 | Example: |
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164 | |
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165 | # wait for readability of STDIN, then read a line and disable the watcher |
198 | Example: wait for readability of STDIN, then read a line and disable the |
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199 | watcher. |
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200 | |
166 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
201 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
167 | chomp (my $input = <STDIN>); |
202 | chomp (my $input = <STDIN>); |
168 | warn "read: $input\n"; |
203 | warn "read: $input\n"; |
169 | undef $w; |
204 | undef $w; |
170 | }); |
205 | }); |
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179 | |
214 | |
180 | Although the callback might get passed parameters, their value and |
215 | Although the callback might get passed parameters, their value and |
181 | presence is undefined and you cannot rely on them. Portable AnyEvent |
216 | presence is undefined and you cannot rely on them. Portable AnyEvent |
182 | callbacks cannot use arguments passed to time watcher callbacks. |
217 | callbacks cannot use arguments passed to time watcher callbacks. |
183 | |
218 | |
184 | The timer callback will be invoked at most once: if you want a repeating |
219 | The callback will normally be invoked once only. If you specify another |
185 | timer you have to create a new watcher (this is a limitation by both Tk |
220 | parameter, "interval", as a strictly positive number (> 0), then the |
186 | and Glib). |
221 | callback will be invoked regularly at that interval (in fractional |
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222 | seconds) after the first invocation. If "interval" is specified with a |
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223 | false value, then it is treated as if it were missing. |
187 | |
224 | |
188 | Example: |
225 | The callback will be rescheduled before invoking the callback, but no |
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226 | attempt is done to avoid timer drift in most backends, so the interval |
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227 | is only approximate. |
189 | |
228 | |
190 | # fire an event after 7.7 seconds |
229 | Example: fire an event after 7.7 seconds. |
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230 | |
191 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
231 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
192 | warn "timeout\n"; |
232 | warn "timeout\n"; |
193 | }); |
233 | }); |
194 | |
234 | |
195 | # to cancel the timer: |
235 | # to cancel the timer: |
196 | undef $w; |
236 | undef $w; |
197 | |
237 | |
198 | Example 2: |
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199 | |
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200 | # fire an event after 0.5 seconds, then roughly every second |
238 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
201 | my $w; |
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202 | |
239 | |
203 | my $cb = sub { |
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204 | # cancel the old timer while creating a new one |
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205 | $w = AnyEvent->timer (after => 1, cb => $cb); |
240 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
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241 | warn "timeout\n"; |
206 | }; |
242 | }; |
207 | |
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208 | # start the "loop" by creating the first watcher |
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209 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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210 | |
243 | |
211 | TIMING ISSUES |
244 | TIMING ISSUES |
212 | There are two ways to handle timers: based on real time (relative, "fire |
245 | There are two ways to handle timers: based on real time (relative, "fire |
213 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
246 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
214 | o'clock"). |
247 | o'clock"). |
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288 | In either case, if you care (and in most cases, you don't), then you |
321 | In either case, if you care (and in most cases, you don't), then you |
289 | can get whatever behaviour you want with any event loop, by taking |
322 | can get whatever behaviour you want with any event loop, by taking |
290 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
323 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
291 | account. |
324 | account. |
292 | |
325 | |
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326 | AnyEvent->now_update |
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327 | Some event loops (such as EV or AnyEvent::Impl::Perl) cache the |
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328 | current time for each loop iteration (see the discussion of |
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329 | AnyEvent->now, above). |
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330 | |
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331 | When a callback runs for a long time (or when the process sleeps), |
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332 | then this "current" time will differ substantially from the real |
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333 | time, which might affect timers and time-outs. |
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334 | |
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335 | When this is the case, you can call this method, which will update |
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336 | the event loop's idea of "current time". |
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337 | |
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338 | Note that updating the time *might* cause some events to be handled. |
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339 | |
293 | SIGNAL WATCHERS |
340 | SIGNAL WATCHERS |
294 | You can watch for signals using a signal watcher, "signal" is the signal |
341 | You can watch for signals using a signal watcher, "signal" is the signal |
295 | *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked |
342 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
296 | whenever a signal occurs. |
343 | callback to be invoked whenever a signal occurs. |
297 | |
344 | |
298 | Although the callback might get passed parameters, their value and |
345 | Although the callback might get passed parameters, their value and |
299 | presence is undefined and you cannot rely on them. Portable AnyEvent |
346 | presence is undefined and you cannot rely on them. Portable AnyEvent |
300 | callbacks cannot use arguments passed to signal watcher callbacks. |
347 | callbacks cannot use arguments passed to signal watcher callbacks. |
301 | |
348 | |
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316 | |
363 | |
317 | CHILD PROCESS WATCHERS |
364 | CHILD PROCESS WATCHERS |
318 | You can also watch on a child process exit and catch its exit status. |
365 | You can also watch on a child process exit and catch its exit status. |
319 | |
366 | |
320 | The child process is specified by the "pid" argument (if set to 0, it |
367 | The child process is specified by the "pid" argument (if set to 0, it |
321 | watches for any child process exit). The watcher will trigger as often |
368 | watches for any child process exit). The watcher will triggered only |
322 | as status change for the child are received. This works by installing a |
369 | when the child process has finished and an exit status is available, not |
323 | signal handler for "SIGCHLD". The callback will be called with the pid |
370 | on any trace events (stopped/continued). |
324 | and exit status (as returned by waitpid), so unlike other watcher types, |
371 | |
325 | you *can* rely on child watcher callback arguments. |
372 | The callback will be called with the pid and exit status (as returned by |
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373 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
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374 | callback arguments. |
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375 | |
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376 | This watcher type works by installing a signal handler for "SIGCHLD", |
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377 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
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378 | random child processes (waiting for specific child processes, e.g. |
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379 | inside "system", is just fine). |
326 | |
380 | |
327 | There is a slight catch to child watchers, however: you usually start |
381 | There is a slight catch to child watchers, however: you usually start |
328 | them *after* the child process was created, and this means the process |
382 | them *after* the child process was created, and this means the process |
329 | could have exited already (and no SIGCHLD will be sent anymore). |
383 | could have exited already (and no SIGCHLD will be sent anymore). |
330 | |
384 | |
331 | Not all event models handle this correctly (POE doesn't), but even for |
385 | Not all event models handle this correctly (neither POE nor IO::Async |
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386 | do, see their AnyEvent::Impl manpages for details), but even for event |
332 | event models that *do* handle this correctly, they usually need to be |
387 | models that *do* handle this correctly, they usually need to be loaded |
333 | loaded before the process exits (i.e. before you fork in the first |
388 | before the process exits (i.e. before you fork in the first place). |
334 | place). |
389 | AnyEvent's pure perl event loop handles all cases correctly regardless |
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390 | of when you start the watcher. |
335 | |
391 | |
336 | This means you cannot create a child watcher as the very first thing in |
392 | This means you cannot create a child watcher as the very first thing in |
337 | an AnyEvent program, you *have* to create at least one watcher before |
393 | an AnyEvent program, you *have* to create at least one watcher before |
338 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
394 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
339 | |
395 | |
340 | Example: fork a process and wait for it |
396 | Example: fork a process and wait for it |
341 | |
397 | |
342 | my $done = AnyEvent->condvar; |
398 | my $done = AnyEvent->condvar; |
343 | |
399 | |
344 | my $pid = fork or exit 5; |
400 | my $pid = fork or exit 5; |
345 | |
401 | |
346 | my $w = AnyEvent->child ( |
402 | my $w = AnyEvent->child ( |
347 | pid => $pid, |
403 | pid => $pid, |
348 | cb => sub { |
404 | cb => sub { |
349 | my ($pid, $status) = @_; |
405 | my ($pid, $status) = @_; |
350 | warn "pid $pid exited with status $status"; |
406 | warn "pid $pid exited with status $status"; |
351 | $done->send; |
407 | $done->send; |
352 | }, |
408 | }, |
353 | ); |
409 | ); |
354 | |
410 | |
355 | # do something else, then wait for process exit |
411 | # do something else, then wait for process exit |
356 | $done->recv; |
412 | $done->recv; |
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413 | |
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414 | IDLE WATCHERS |
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415 | Sometimes there is a need to do something, but it is not so important to |
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416 | do it instantly, but only when there is nothing better to do. This |
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417 | "nothing better to do" is usually defined to be "no other events need |
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418 | attention by the event loop". |
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419 | |
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420 | Idle watchers ideally get invoked when the event loop has nothing better |
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421 | to do, just before it would block the process to wait for new events. |
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422 | Instead of blocking, the idle watcher is invoked. |
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423 | |
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424 | Most event loops unfortunately do not really support idle watchers (only |
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425 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
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426 | will simply call the callback "from time to time". |
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427 | |
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428 | Example: read lines from STDIN, but only process them when the program |
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429 | is otherwise idle: |
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430 | |
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431 | my @lines; # read data |
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432 | my $idle_w; |
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433 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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434 | push @lines, scalar <STDIN>; |
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435 | |
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436 | # start an idle watcher, if not already done |
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437 | $idle_w ||= AnyEvent->idle (cb => sub { |
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438 | # handle only one line, when there are lines left |
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439 | if (my $line = shift @lines) { |
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440 | print "handled when idle: $line"; |
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441 | } else { |
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442 | # otherwise disable the idle watcher again |
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443 | undef $idle_w; |
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444 | } |
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445 | }); |
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446 | }); |
357 | |
447 | |
358 | CONDITION VARIABLES |
448 | CONDITION VARIABLES |
359 | If you are familiar with some event loops you will know that all of them |
449 | If you are familiar with some event loops you will know that all of them |
360 | require you to run some blocking "loop", "run" or similar function that |
450 | require you to run some blocking "loop", "run" or similar function that |
361 | will actively watch for new events and call your callbacks. |
451 | will actively watch for new events and call your callbacks. |
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366 | The instrument to do that is called a "condition variable", so called |
456 | The instrument to do that is called a "condition variable", so called |
367 | because they represent a condition that must become true. |
457 | because they represent a condition that must become true. |
368 | |
458 | |
369 | Condition variables can be created by calling the "AnyEvent->condvar" |
459 | Condition variables can be created by calling the "AnyEvent->condvar" |
370 | method, usually without arguments. The only argument pair allowed is |
460 | method, usually without arguments. The only argument pair allowed is |
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461 | |
371 | "cb", which specifies a callback to be called when the condition |
462 | "cb", which specifies a callback to be called when the condition |
372 | variable becomes true. |
463 | variable becomes true, with the condition variable as the first argument |
|
|
464 | (but not the results). |
373 | |
465 | |
374 | After creation, the condition variable is "false" until it becomes |
466 | After creation, the condition variable is "false" until it becomes |
375 | "true" by calling the "send" method (or calling the condition variable |
467 | "true" by calling the "send" method (or calling the condition variable |
376 | as if it were a callback, read about the caveats in the description for |
468 | as if it were a callback, read about the caveats in the description for |
377 | the "->send" method). |
469 | the "->send" method). |
… | |
… | |
433 | |
525 | |
434 | my $done = AnyEvent->condvar; |
526 | my $done = AnyEvent->condvar; |
435 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
527 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
436 | $done->recv; |
528 | $done->recv; |
437 | |
529 | |
|
|
530 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
531 | callbacks. This is how you make a synchronous call, for example from the |
|
|
532 | main program: |
|
|
533 | |
|
|
534 | use AnyEvent::CouchDB; |
|
|
535 | |
|
|
536 | ... |
|
|
537 | |
|
|
538 | my @info = $couchdb->info->recv; |
|
|
539 | |
|
|
540 | And this is how you would just ste a callback to be called whenever the |
|
|
541 | results are available: |
|
|
542 | |
|
|
543 | $couchdb->info->cb (sub { |
|
|
544 | my @info = $_[0]->recv; |
|
|
545 | }); |
|
|
546 | |
438 | METHODS FOR PRODUCERS |
547 | METHODS FOR PRODUCERS |
439 | These methods should only be used by the producing side, i.e. the |
548 | These methods should only be used by the producing side, i.e. the |
440 | code/module that eventually sends the signal. Note that it is also the |
549 | code/module that eventually sends the signal. Note that it is also the |
441 | producer side which creates the condvar in most cases, but it isn't |
550 | producer side which creates the condvar in most cases, but it isn't |
442 | uncommon for the consumer to create it as well. |
551 | uncommon for the consumer to create it as well. |
… | |
… | |
468 | This can be used to signal any errors to the condition variable |
577 | This can be used to signal any errors to the condition variable |
469 | user/consumer. |
578 | user/consumer. |
470 | |
579 | |
471 | $cv->begin ([group callback]) |
580 | $cv->begin ([group callback]) |
472 | $cv->end |
581 | $cv->end |
473 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
474 | |
|
|
475 | These two methods can be used to combine many transactions/events |
582 | These two methods can be used to combine many transactions/events |
476 | into one. For example, a function that pings many hosts in parallel |
583 | into one. For example, a function that pings many hosts in parallel |
477 | might want to use a condition variable for the whole process. |
584 | might want to use a condition variable for the whole process. |
478 | |
585 | |
479 | Every call to "->begin" will increment a counter, and every call to |
586 | Every call to "->begin" will increment a counter, and every call to |
480 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
587 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
481 | (last) callback passed to "begin" will be executed. That callback is |
588 | (last) callback passed to "begin" will be executed. That callback is |
482 | *supposed* to call "->send", but that is not required. If no |
589 | *supposed* to call "->send", but that is not required. If no |
483 | callback was set, "send" will be called without any arguments. |
590 | callback was set, "send" will be called without any arguments. |
484 | |
591 | |
485 | Let's clarify this with the ping example: |
592 | You can think of "$cv->send" giving you an OR condition (one call |
|
|
593 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
|
|
594 | condition (all "begin" calls must be "end"'ed before the condvar |
|
|
595 | sends). |
|
|
596 | |
|
|
597 | Let's start with a simple example: you have two I/O watchers (for |
|
|
598 | example, STDOUT and STDERR for a program), and you want to wait for |
|
|
599 | both streams to close before activating a condvar: |
|
|
600 | |
|
|
601 | my $cv = AnyEvent->condvar; |
|
|
602 | |
|
|
603 | $cv->begin; # first watcher |
|
|
604 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
|
|
605 | defined sysread $fh1, my $buf, 4096 |
|
|
606 | or $cv->end; |
|
|
607 | }); |
|
|
608 | |
|
|
609 | $cv->begin; # second watcher |
|
|
610 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
|
|
611 | defined sysread $fh2, my $buf, 4096 |
|
|
612 | or $cv->end; |
|
|
613 | }); |
|
|
614 | |
|
|
615 | $cv->recv; |
|
|
616 | |
|
|
617 | This works because for every event source (EOF on file handle), |
|
|
618 | there is one call to "begin", so the condvar waits for all calls to |
|
|
619 | "end" before sending. |
|
|
620 | |
|
|
621 | The ping example mentioned above is slightly more complicated, as |
|
|
622 | the there are results to be passwd back, and the number of tasks |
|
|
623 | that are begung can potentially be zero: |
486 | |
624 | |
487 | my $cv = AnyEvent->condvar; |
625 | my $cv = AnyEvent->condvar; |
488 | |
626 | |
489 | my %result; |
627 | my %result; |
490 | $cv->begin (sub { $cv->send (\%result) }); |
628 | $cv->begin (sub { $cv->send (\%result) }); |
… | |
… | |
510 | the loop, which serves two important purposes: first, it sets the |
648 | the loop, which serves two important purposes: first, it sets the |
511 | callback to be called once the counter reaches 0, and second, it |
649 | callback to be called once the counter reaches 0, and second, it |
512 | ensures that "send" is called even when "no" hosts are being pinged |
650 | ensures that "send" is called even when "no" hosts are being pinged |
513 | (the loop doesn't execute once). |
651 | (the loop doesn't execute once). |
514 | |
652 | |
515 | This is the general pattern when you "fan out" into multiple |
653 | This is the general pattern when you "fan out" into multiple (but |
516 | subrequests: use an outer "begin"/"end" pair to set the callback and |
654 | potentially none) subrequests: use an outer "begin"/"end" pair to |
517 | ensure "end" is called at least once, and then, for each subrequest |
655 | set the callback and ensure "end" is called at least once, and then, |
518 | you start, call "begin" and for each subrequest you finish, call |
656 | for each subrequest you start, call "begin" and for each subrequest |
519 | "end". |
657 | you finish, call "end". |
520 | |
658 | |
521 | METHODS FOR CONSUMERS |
659 | METHODS FOR CONSUMERS |
522 | These methods should only be used by the consuming side, i.e. the code |
660 | These methods should only be used by the consuming side, i.e. the code |
523 | awaits the condition. |
661 | awaits the condition. |
524 | |
662 | |
… | |
… | |
562 | |
700 | |
563 | $bool = $cv->ready |
701 | $bool = $cv->ready |
564 | Returns true when the condition is "true", i.e. whether "send" or |
702 | Returns true when the condition is "true", i.e. whether "send" or |
565 | "croak" have been called. |
703 | "croak" have been called. |
566 | |
704 | |
567 | $cb = $cv->cb ([new callback]) |
705 | $cb = $cv->cb ($cb->($cv)) |
568 | This is a mutator function that returns the callback set and |
706 | This is a mutator function that returns the callback set and |
569 | optionally replaces it before doing so. |
707 | optionally replaces it before doing so. |
570 | |
708 | |
571 | The callback will be called when the condition becomes "true", i.e. |
709 | The callback will be called when the condition becomes "true", i.e. |
572 | when "send" or "croak" are called. Calling "recv" inside the |
710 | when "send" or "croak" are called, with the only argument being the |
|
|
711 | condition variable itself. Calling "recv" inside the callback or at |
573 | callback or at any later time is guaranteed not to block. |
712 | any later time is guaranteed not to block. |
574 | |
713 | |
575 | GLOBAL VARIABLES AND FUNCTIONS |
714 | GLOBAL VARIABLES AND FUNCTIONS |
576 | $AnyEvent::MODEL |
715 | $AnyEvent::MODEL |
577 | Contains "undef" until the first watcher is being created. Then it |
716 | Contains "undef" until the first watcher is being created. Then it |
578 | contains the event model that is being used, which is the name of |
717 | contains the event model that is being used, which is the name of |
… | |
… | |
589 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
728 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
590 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
729 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
591 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
730 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
592 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
731 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
593 | |
732 | |
|
|
733 | # warning, support for IO::Async is only partial, as it is too broken |
|
|
734 | # and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async. |
|
|
735 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs). |
|
|
736 | |
594 | There is no support for WxWidgets, as WxWidgets has no support for |
737 | There is no support for WxWidgets, as WxWidgets has no support for |
595 | watching file handles. However, you can use WxWidgets through the |
738 | watching file handles. However, you can use WxWidgets through the |
596 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
739 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
597 | second, which was considered to be too horrible to even consider for |
740 | second, which was considered to be too horrible to even consider for |
598 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by |
741 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by |
… | |
… | |
692 | AnyEvent::Util |
835 | AnyEvent::Util |
693 | Contains various utility functions that replace often-used but |
836 | Contains various utility functions that replace often-used but |
694 | blocking functions such as "inet_aton" by event-/callback-based |
837 | blocking functions such as "inet_aton" by event-/callback-based |
695 | versions. |
838 | versions. |
696 | |
839 | |
697 | AnyEvent::Handle |
|
|
698 | Provide read and write buffers and manages watchers for reads and |
|
|
699 | writes. |
|
|
700 | |
|
|
701 | AnyEvent::Socket |
840 | AnyEvent::Socket |
702 | Provides various utility functions for (internet protocol) sockets, |
841 | Provides various utility functions for (internet protocol) sockets, |
703 | addresses and name resolution. Also functions to create non-blocking |
842 | addresses and name resolution. Also functions to create non-blocking |
704 | tcp connections or tcp servers, with IPv6 and SRV record support and |
843 | tcp connections or tcp servers, with IPv6 and SRV record support and |
705 | more. |
844 | more. |
706 | |
845 | |
|
|
846 | AnyEvent::Handle |
|
|
847 | Provide read and write buffers, manages watchers for reads and |
|
|
848 | writes, supports raw and formatted I/O, I/O queued and fully |
|
|
849 | transparent and non-blocking SSL/TLS. |
|
|
850 | |
707 | AnyEvent::DNS |
851 | AnyEvent::DNS |
708 | Provides rich asynchronous DNS resolver capabilities. |
852 | Provides rich asynchronous DNS resolver capabilities. |
709 | |
853 | |
|
|
854 | AnyEvent::HTTP |
|
|
855 | A simple-to-use HTTP library that is capable of making a lot of |
|
|
856 | concurrent HTTP requests. |
|
|
857 | |
710 | AnyEvent::HTTPD |
858 | AnyEvent::HTTPD |
711 | Provides a simple web application server framework. |
859 | Provides a simple web application server framework. |
712 | |
860 | |
713 | AnyEvent::FastPing |
861 | AnyEvent::FastPing |
714 | The fastest ping in the west. |
862 | The fastest ping in the west. |
715 | |
863 | |
|
|
864 | AnyEvent::DBI |
|
|
865 | Executes DBI requests asynchronously in a proxy process. |
|
|
866 | |
|
|
867 | AnyEvent::AIO |
|
|
868 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
869 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
870 | together. |
|
|
871 | |
|
|
872 | AnyEvent::BDB |
|
|
873 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
874 | fuses BDB and AnyEvent together. |
|
|
875 | |
|
|
876 | AnyEvent::GPSD |
|
|
877 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
878 | information. |
|
|
879 | |
|
|
880 | AnyEvent::IGS |
|
|
881 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
882 | App::IGS). |
|
|
883 | |
|
|
884 | AnyEvent::IRC |
|
|
885 | AnyEvent based IRC client module family (replacing the older |
716 | Net::IRC3 |
886 | Net::IRC3). |
717 | AnyEvent based IRC client module family. |
|
|
718 | |
887 | |
719 | Net::XMPP2 |
888 | Net::XMPP2 |
720 | AnyEvent based XMPP (Jabber protocol) module family. |
889 | AnyEvent based XMPP (Jabber protocol) module family. |
721 | |
890 | |
722 | Net::FCP |
891 | Net::FCP |
… | |
… | |
727 | High level API for event-based execution flow control. |
896 | High level API for event-based execution flow control. |
728 | |
897 | |
729 | Coro |
898 | Coro |
730 | Has special support for AnyEvent via Coro::AnyEvent. |
899 | Has special support for AnyEvent via Coro::AnyEvent. |
731 | |
900 | |
732 | AnyEvent::AIO, IO::AIO |
|
|
733 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
734 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
735 | together. |
|
|
736 | |
|
|
737 | AnyEvent::BDB, BDB |
|
|
738 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently |
|
|
739 | fuses IO::AIO and AnyEvent together. |
|
|
740 | |
|
|
741 | IO::Lambda |
901 | IO::Lambda |
742 | The lambda approach to I/O - don't ask, look there. Can use |
902 | The lambda approach to I/O - don't ask, look there. Can use |
743 | AnyEvent. |
903 | AnyEvent. |
744 | |
904 | |
745 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
905 | ERROR AND EXCEPTION HANDLING |
746 | This is an advanced topic that you do not normally need to use AnyEvent |
906 | In general, AnyEvent does not do any error handling - it relies on the |
747 | in a module. This section is only of use to event loop authors who want |
907 | caller to do that if required. The AnyEvent::Strict module (see also the |
748 | to provide AnyEvent compatibility. |
908 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
|
|
909 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
910 | development. |
749 | |
911 | |
750 | If you need to support another event library which isn't directly |
912 | As for exception handling (i.e. runtime errors and exceptions thrown |
751 | supported by AnyEvent, you can supply your own interface to it by |
913 | while executing a callback), this is not only highly event-loop |
752 | pushing, before the first watcher gets created, the package name of the |
914 | specific, but also not in any way wrapped by this module, as this is the |
753 | event module and the package name of the interface to use onto |
915 | job of the main program. |
754 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
755 | AnyEvent, so it is reasonably cheap. |
|
|
756 | |
916 | |
757 | Example: |
917 | The pure perl event loop simply re-throws the exception (usually within |
758 | |
918 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
759 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
919 | Glib uses "install_exception_handler" and so on. |
760 | |
|
|
761 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
762 | package/class when it finds the "urxvt" package/module is already |
|
|
763 | loaded. |
|
|
764 | |
|
|
765 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
766 | will first check for the presence of urxvt by trying to "use" the |
|
|
767 | "urxvt::anyevent" module. |
|
|
768 | |
|
|
769 | The class should provide implementations for all watcher types. See |
|
|
770 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
771 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
772 | the sources. |
|
|
773 | |
|
|
774 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
775 | provide suitable (hopefully) replacements. |
|
|
776 | |
|
|
777 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
778 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
779 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
780 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
781 | part of the *rxvt-unicode* distribution. |
|
|
782 | |
|
|
783 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
784 | condition variables: code blocking while waiting for a condition will |
|
|
785 | "die". This still works with most modules/usages, and blocking calls |
|
|
786 | must not be done in an interactive application, so it makes sense. |
|
|
787 | |
920 | |
788 | ENVIRONMENT VARIABLES |
921 | ENVIRONMENT VARIABLES |
789 | The following environment variables are used by this module: |
922 | The following environment variables are used by this module or its |
|
|
923 | submodules. |
|
|
924 | |
|
|
925 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
926 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
927 | enabled. |
790 | |
928 | |
791 | "PERL_ANYEVENT_VERBOSE" |
929 | "PERL_ANYEVENT_VERBOSE" |
792 | By default, AnyEvent will be completely silent except in fatal |
930 | By default, AnyEvent will be completely silent except in fatal |
793 | conditions. You can set this environment variable to make AnyEvent |
931 | conditions. You can set this environment variable to make AnyEvent |
794 | more talkative. |
932 | more talkative. |
… | |
… | |
797 | conditions, such as not being able to load the event model specified |
935 | conditions, such as not being able to load the event model specified |
798 | by "PERL_ANYEVENT_MODEL". |
936 | by "PERL_ANYEVENT_MODEL". |
799 | |
937 | |
800 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
938 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
801 | event model it chooses. |
939 | event model it chooses. |
|
|
940 | |
|
|
941 | "PERL_ANYEVENT_STRICT" |
|
|
942 | AnyEvent does not do much argument checking by default, as thorough |
|
|
943 | argument checking is very costly. Setting this variable to a true |
|
|
944 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
|
|
945 | thoroughly check the arguments passed to most method calls. If it |
|
|
946 | finds any problems, it will croak. |
|
|
947 | |
|
|
948 | In other words, enables "strict" mode. |
|
|
949 | |
|
|
950 | Unlike "use strict", it is definitely recommended to keep it off in |
|
|
951 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
|
|
952 | while developing programs can be very useful, however. |
802 | |
953 | |
803 | "PERL_ANYEVENT_MODEL" |
954 | "PERL_ANYEVENT_MODEL" |
804 | This can be used to specify the event model to be used by AnyEvent, |
955 | This can be used to specify the event model to be used by AnyEvent, |
805 | before auto detection and -probing kicks in. It must be a string |
956 | before auto detection and -probing kicks in. It must be a string |
806 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
957 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
811 | This functionality might change in future versions. |
962 | This functionality might change in future versions. |
812 | |
963 | |
813 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
964 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
814 | could start your program like this: |
965 | could start your program like this: |
815 | |
966 | |
816 | PERL_ANYEVENT_MODEL=Perl perl ... |
967 | PERL_ANYEVENT_MODEL=Perl perl ... |
817 | |
968 | |
818 | "PERL_ANYEVENT_PROTOCOLS" |
969 | "PERL_ANYEVENT_PROTOCOLS" |
819 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
970 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
820 | preferences for IPv4 or IPv6. The default is unspecified (and might |
971 | preferences for IPv4 or IPv6. The default is unspecified (and might |
821 | change, or be the result of auto probing). |
972 | change, or be the result of auto probing). |
… | |
… | |
825 | mentioned will be used, and preference will be given to protocols |
976 | mentioned will be used, and preference will be given to protocols |
826 | mentioned earlier in the list. |
977 | mentioned earlier in the list. |
827 | |
978 | |
828 | This variable can effectively be used for denial-of-service attacks |
979 | This variable can effectively be used for denial-of-service attacks |
829 | against local programs (e.g. when setuid), although the impact is |
980 | against local programs (e.g. when setuid), although the impact is |
830 | likely small, as the program has to handle connection errors |
981 | likely small, as the program has to handle conenction and other |
831 | already- |
982 | failures anyways. |
832 | |
983 | |
833 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
984 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
834 | IPv6, but support both and try to use both. |
985 | IPv6, but support both and try to use both. |
835 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
986 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
836 | resolve or contact IPv6 addresses. |
987 | resolve or contact IPv6 addresses. |
… | |
… | |
847 | EDNS0 in its DNS requests. |
998 | EDNS0 in its DNS requests. |
848 | |
999 | |
849 | "PERL_ANYEVENT_MAX_FORKS" |
1000 | "PERL_ANYEVENT_MAX_FORKS" |
850 | The maximum number of child processes that |
1001 | The maximum number of child processes that |
851 | "AnyEvent::Util::fork_call" will create in parallel. |
1002 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
1003 | |
|
|
1004 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1005 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
1006 | in a module. This section is only of use to event loop authors who want |
|
|
1007 | to provide AnyEvent compatibility. |
|
|
1008 | |
|
|
1009 | If you need to support another event library which isn't directly |
|
|
1010 | supported by AnyEvent, you can supply your own interface to it by |
|
|
1011 | pushing, before the first watcher gets created, the package name of the |
|
|
1012 | event module and the package name of the interface to use onto |
|
|
1013 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
1014 | AnyEvent, so it is reasonably cheap. |
|
|
1015 | |
|
|
1016 | Example: |
|
|
1017 | |
|
|
1018 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
1019 | |
|
|
1020 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
1021 | package/class when it finds the "urxvt" package/module is already |
|
|
1022 | loaded. |
|
|
1023 | |
|
|
1024 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
1025 | will first check for the presence of urxvt by trying to "use" the |
|
|
1026 | "urxvt::anyevent" module. |
|
|
1027 | |
|
|
1028 | The class should provide implementations for all watcher types. See |
|
|
1029 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
1030 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
1031 | the sources. |
|
|
1032 | |
|
|
1033 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
1034 | provide suitable (hopefully) replacements. |
|
|
1035 | |
|
|
1036 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
1037 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
1038 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
1039 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
1040 | part of the *rxvt-unicode* distribution. |
|
|
1041 | |
|
|
1042 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
1043 | condition variables: code blocking while waiting for a condition will |
|
|
1044 | "die". This still works with most modules/usages, and blocking calls |
|
|
1045 | must not be done in an interactive application, so it makes sense. |
852 | |
1046 | |
853 | EXAMPLE PROGRAM |
1047 | EXAMPLE PROGRAM |
854 | The following program uses an I/O watcher to read data from STDIN, a |
1048 | The following program uses an I/O watcher to read data from STDIN, a |
855 | timer to display a message once per second, and a condition variable to |
1049 | timer to display a message once per second, and a condition variable to |
856 | quit the program when the user enters quit: |
1050 | quit the program when the user enters quit: |
… | |
… | |
1043 | *destroy* is the time, in microseconds, that it takes to destroy a |
1237 | *destroy* is the time, in microseconds, that it takes to destroy a |
1044 | single watcher. |
1238 | single watcher. |
1045 | |
1239 | |
1046 | Results |
1240 | Results |
1047 | name watchers bytes create invoke destroy comment |
1241 | name watchers bytes create invoke destroy comment |
1048 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1242 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
1049 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1243 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1050 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1244 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1051 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1245 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1052 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1246 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1053 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
1247 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1248 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
|
|
1249 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
1054 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1250 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1055 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1251 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1056 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1252 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1057 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1253 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1058 | |
1254 | |
1059 | Discussion |
1255 | Discussion |
1060 | The benchmark does *not* measure scalability of the event loop very |
1256 | The benchmark does *not* measure scalability of the event loop very |
1061 | well. For example, a select-based event loop (such as the pure perl one) |
1257 | well. For example, a select-based event loop (such as the pure perl one) |
1062 | can never compete with an event loop that uses epoll when the number of |
1258 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1087 | few of them active), of course, but this was not subject of this |
1283 | few of them active), of course, but this was not subject of this |
1088 | benchmark. |
1284 | benchmark. |
1089 | |
1285 | |
1090 | The "Event" module has a relatively high setup and callback invocation |
1286 | The "Event" module has a relatively high setup and callback invocation |
1091 | cost, but overall scores in on the third place. |
1287 | cost, but overall scores in on the third place. |
|
|
1288 | |
|
|
1289 | "IO::Async" performs admirably well, about on par with "Event", even |
|
|
1290 | when using its pure perl backend. |
1092 | |
1291 | |
1093 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1292 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1094 | callback invocation and overall ends up in the same class as "Event". |
1293 | callback invocation and overall ends up in the same class as "Event". |
1095 | However, Glib scales extremely badly, doubling the number of watchers |
1294 | However, Glib scales extremely badly, doubling the number of watchers |
1096 | increases the processing time by more than a factor of four, making it |
1295 | increases the processing time by more than a factor of four, making it |
… | |
… | |
1167 | single "request", that is, reading the token from the pipe and |
1366 | single "request", that is, reading the token from the pipe and |
1168 | forwarding it to another server. This includes deleting the old timeout |
1367 | forwarding it to another server. This includes deleting the old timeout |
1169 | and creating a new one that moves the timeout into the future. |
1368 | and creating a new one that moves the timeout into the future. |
1170 | |
1369 | |
1171 | Results |
1370 | Results |
1172 | name sockets create request |
1371 | name sockets create request |
1173 | EV 20000 69.01 11.16 |
1372 | EV 20000 69.01 11.16 |
1174 | Perl 20000 73.32 35.87 |
1373 | Perl 20000 73.32 35.87 |
|
|
1374 | IOAsync 20000 157.00 98.14 epoll |
|
|
1375 | IOAsync 20000 159.31 616.06 poll |
1175 | Event 20000 212.62 257.32 |
1376 | Event 20000 212.62 257.32 |
1176 | Glib 20000 651.16 1896.30 |
1377 | Glib 20000 651.16 1896.30 |
1177 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1378 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1178 | |
1379 | |
1179 | Discussion |
1380 | Discussion |
1180 | This benchmark *does* measure scalability and overall performance of the |
1381 | This benchmark *does* measure scalability and overall performance of the |
1181 | particular event loop. |
1382 | particular event loop. |
1182 | |
1383 | |
1183 | EV is again fastest. Since it is using epoll on my system, the setup |
1384 | EV is again fastest. Since it is using epoll on my system, the setup |
1184 | time is relatively high, though. |
1385 | time is relatively high, though. |
1185 | |
1386 | |
1186 | Perl surprisingly comes second. It is much faster than the C-based event |
1387 | Perl surprisingly comes second. It is much faster than the C-based event |
1187 | loops Event and Glib. |
1388 | loops Event and Glib. |
|
|
1389 | |
|
|
1390 | IO::Async performs very well when using its epoll backend, and still |
|
|
1391 | quite good compared to Glib when using its pure perl backend. |
1188 | |
1392 | |
1189 | Event suffers from high setup time as well (look at its code and you |
1393 | Event suffers from high setup time as well (look at its code and you |
1190 | will understand why). Callback invocation also has a high overhead |
1394 | will understand why). Callback invocation also has a high overhead |
1191 | compared to the "$_->() for .."-style loop that the Perl event loop |
1395 | compared to the "$_->() for .."-style loop that the Perl event loop |
1192 | uses. Event uses select or poll in basically all documented |
1396 | uses. Event uses select or poll in basically all documented |
… | |
… | |
1243 | |
1447 | |
1244 | Summary |
1448 | Summary |
1245 | * C-based event loops perform very well with small number of watchers, |
1449 | * C-based event loops perform very well with small number of watchers, |
1246 | as the management overhead dominates. |
1450 | as the management overhead dominates. |
1247 | |
1451 | |
|
|
1452 | THE IO::Lambda BENCHMARK |
|
|
1453 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
1454 | could be misinterpreted to make AnyEvent look bad. In fact, the |
|
|
1455 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
|
|
1456 | better (which shouldn't come as a surprise to anybody). As such, the |
|
|
1457 | benchmark is fine, and mostly shows that the AnyEvent backend from |
|
|
1458 | IO::Lambda isn't very optimal. But how would AnyEvent compare when used |
|
|
1459 | without the extra baggage? To explore this, I wrote the equivalent |
|
|
1460 | benchmark for AnyEvent. |
|
|
1461 | |
|
|
1462 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
1463 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
1464 | creates the next connection. This is a rather bad benchmark, as it |
|
|
1465 | doesn't test the efficiency of the framework or much non-blocking I/O, |
|
|
1466 | but it is a benchmark nevertheless. |
|
|
1467 | |
|
|
1468 | name runtime |
|
|
1469 | Lambda/select 0.330 sec |
|
|
1470 | + optimized 0.122 sec |
|
|
1471 | Lambda/AnyEvent 0.327 sec |
|
|
1472 | + optimized 0.138 sec |
|
|
1473 | Raw sockets/select 0.077 sec |
|
|
1474 | POE/select, components 0.662 sec |
|
|
1475 | POE/select, raw sockets 0.226 sec |
|
|
1476 | POE/select, optimized 0.404 sec |
|
|
1477 | |
|
|
1478 | AnyEvent/select/nb 0.085 sec |
|
|
1479 | AnyEvent/EV/nb 0.068 sec |
|
|
1480 | +state machine 0.134 sec |
|
|
1481 | |
|
|
1482 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
|
|
1483 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
1484 | defeating the purpose of an event-based solution. All of the newly |
|
|
1485 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
1486 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
1487 | resolver), so AnyEvent is at a disadvantage here, as non-blocking |
|
|
1488 | connects generally require a lot more bookkeeping and event handling |
|
|
1489 | than blocking connects (which involve a single syscall only). |
|
|
1490 | |
|
|
1491 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
|
|
1492 | offers similar expressive power as POE and IO::Lambda, using |
|
|
1493 | conventional Perl syntax. This means that both the echo server and the |
|
|
1494 | client are 100% non-blocking, further placing it at a disadvantage. |
|
|
1495 | |
|
|
1496 | As you can see, the AnyEvent + EV combination even beats the |
|
|
1497 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
|
|
1498 | backend easily beats IO::Lambda and POE. |
|
|
1499 | |
|
|
1500 | And even the 100% non-blocking version written using the high-level (and |
|
|
1501 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
|
|
1502 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
|
|
1503 | in a non-blocking way. |
|
|
1504 | |
|
|
1505 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
|
|
1506 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
|
|
1507 | part of the IO::lambda distribution and were used without any changes. |
|
|
1508 | |
|
|
1509 | SIGNALS |
|
|
1510 | AnyEvent currently installs handlers for these signals: |
|
|
1511 | |
|
|
1512 | SIGCHLD |
|
|
1513 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
|
|
1514 | emulation for event loops that do not support them natively. Also, |
|
|
1515 | some event loops install a similar handler. |
|
|
1516 | |
|
|
1517 | If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent |
|
|
1518 | will reset it to default, to avoid losing child exit statuses. |
|
|
1519 | |
|
|
1520 | SIGPIPE |
|
|
1521 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
|
|
1522 | "undef" when AnyEvent gets loaded. |
|
|
1523 | |
|
|
1524 | The rationale for this is that AnyEvent users usually do not really |
|
|
1525 | depend on SIGPIPE delivery (which is purely an optimisation for |
|
|
1526 | shell use, or badly-written programs), but "SIGPIPE" can cause |
|
|
1527 | spurious and rare program exits as a lot of people do not expect |
|
|
1528 | "SIGPIPE" when writing to some random socket. |
|
|
1529 | |
|
|
1530 | The rationale for installing a no-op handler as opposed to ignoring |
|
|
1531 | it is that this way, the handler will be restored to defaults on |
|
|
1532 | exec. |
|
|
1533 | |
|
|
1534 | Feel free to install your own handler, or reset it to defaults. |
|
|
1535 | |
1248 | FORK |
1536 | FORK |
1249 | Most event libraries are not fork-safe. The ones who are usually are |
1537 | Most event libraries are not fork-safe. The ones who are usually are |
1250 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1538 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1251 | Only EV is fully fork-aware. |
1539 | Only EV is fully fork-aware. |
1252 | |
1540 | |
… | |
… | |
1262 | model than specified in the variable. |
1550 | model than specified in the variable. |
1263 | |
1551 | |
1264 | You can make AnyEvent completely ignore this variable by deleting it |
1552 | You can make AnyEvent completely ignore this variable by deleting it |
1265 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1553 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1266 | |
1554 | |
1267 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1555 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1268 | |
1556 | |
1269 | use AnyEvent; |
1557 | use AnyEvent; |
1270 | |
1558 | |
1271 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1559 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1272 | be used to probe what backend is used and gain other information (which |
1560 | be used to probe what backend is used and gain other information (which |
1273 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
1561 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
|
|
1562 | and $ENV{PERL_ANYEVENT_STRICT}. |
|
|
1563 | |
|
|
1564 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1565 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1566 | enabled. |
|
|
1567 | |
|
|
1568 | BUGS |
|
|
1569 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
|
|
1570 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
|
|
1571 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
|
|
1572 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
|
|
1573 | not as pronounced). |
1274 | |
1574 | |
1275 | SEE ALSO |
1575 | SEE ALSO |
1276 | Utility functions: AnyEvent::Util. |
1576 | Utility functions: AnyEvent::Util. |
1277 | |
1577 | |
1278 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1578 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
… | |
… | |
1290 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1590 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1291 | |
1591 | |
1292 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1592 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1293 | |
1593 | |
1294 | AUTHOR |
1594 | AUTHOR |
1295 | Marc Lehmann <schmorp@schmorp.de> |
1595 | Marc Lehmann <schmorp@schmorp.de> |
1296 | http://home.schmorp.de/ |
1596 | http://home.schmorp.de/ |
1297 | |
1597 | |