… | |
… | |
5 | Qt and POE are various supported event loops/environments. |
5 | Qt and POE are various supported event loops/environments. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
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10 | # if you prefer function calls, look at the AE manpage for |
|
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11 | # an alternative API. |
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12 | |
10 | # file descriptor readable |
13 | # file handle or descriptor readable |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
14 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
12 | |
15 | |
13 | # one-shot or repeating timers |
16 | # one-shot or repeating timers |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
17 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
18 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...); |
16 | |
19 | |
17 | print AnyEvent->now; # prints current event loop time |
20 | print AnyEvent->now; # prints current event loop time |
18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
21 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
19 | |
22 | |
20 | # POSIX signal |
23 | # POSIX signal |
… | |
… | |
39 | This manpage is mainly a reference manual. If you are interested in a |
42 | This manpage is mainly a reference manual. If you are interested in a |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
43 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
41 | manpage. |
44 | manpage. |
42 | |
45 | |
43 | SUPPORT |
46 | SUPPORT |
|
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47 | An FAQ document is available as AnyEvent::FAQ. |
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48 | |
44 | There is a mailinglist for discussing all things AnyEvent, and an IRC |
49 | There also is a mailinglist for discussing all things AnyEvent, and an |
45 | channel, too. |
50 | IRC channel, too. |
46 | |
51 | |
47 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
52 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
48 | Repository, at <http://anyevent.schmorp.de>, for more info. |
53 | Repository, at <http://anyevent.schmorp.de>, for more info. |
49 | |
54 | |
50 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
55 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
… | |
… | |
68 | module users into the same thing by forcing them to use the same event |
73 | module users into the same thing by forcing them to use the same event |
69 | model you use. |
74 | model you use. |
70 | |
75 | |
71 | For modules like POE or IO::Async (which is a total misnomer as it is |
76 | For modules like POE or IO::Async (which is a total misnomer as it is |
72 | actually doing all I/O *synchronously*...), using them in your module is |
77 | actually doing all I/O *synchronously*...), using them in your module is |
73 | like joining a cult: After you joined, you are dependent on them and you |
78 | like joining a cult: After you join, you are dependent on them and you |
74 | cannot use anything else, as they are simply incompatible to everything |
79 | cannot use anything else, as they are simply incompatible to everything |
75 | that isn't them. What's worse, all the potential users of your module |
80 | that isn't them. What's worse, all the potential users of your module |
76 | are *also* forced to use the same event loop you use. |
81 | are *also* forced to use the same event loop you use. |
77 | |
82 | |
78 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
83 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
79 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
84 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
80 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
85 | with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module |
81 | module uses one of those, every user of your module has to use it, too. |
86 | uses one of those, every user of your module has to use it, too. But if |
82 | But if your module uses AnyEvent, it works transparently with all event |
87 | your module uses AnyEvent, it works transparently with all event models |
83 | models it supports (including stuff like IO::Async, as long as those use |
88 | it supports (including stuff like IO::Async, as long as those use one of |
84 | one of the supported event loops. It is trivial to add new event loops |
89 | the supported event loops. It is easy to add new event loops to |
85 | to AnyEvent, too, so it is future-proof). |
90 | AnyEvent, too, so it is future-proof). |
86 | |
91 | |
87 | In addition to being free of having to use *the one and only true event |
92 | In addition to being free of having to use *the one and only true event |
88 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
93 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
89 | modules, you get an enormous amount of code and strict rules you have to |
94 | modules, you get an enormous amount of code and strict rules you have to |
90 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
95 | follow. AnyEvent, on the other hand, is lean and to the point, by only |
91 | only offering the functionality that is necessary, in as thin as a |
96 | offering the functionality that is necessary, in as thin as a wrapper as |
92 | wrapper as technically possible. |
97 | technically possible. |
93 | |
98 | |
94 | Of course, AnyEvent comes with a big (and fully optional!) toolbox of |
99 | Of course, AnyEvent comes with a big (and fully optional!) toolbox of |
95 | useful functionality, such as an asynchronous DNS resolver, 100% |
100 | useful functionality, such as an asynchronous DNS resolver, 100% |
96 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
101 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
97 | such as Windows) and lots of real-world knowledge and workarounds for |
102 | such as Windows) and lots of real-world knowledge and workarounds for |
… | |
… | |
100 | Now, if you *do want* lots of policy (this can arguably be somewhat |
105 | Now, if you *do want* lots of policy (this can arguably be somewhat |
101 | useful) and you want to force your users to use the one and only event |
106 | useful) and you want to force your users to use the one and only event |
102 | model, you should *not* use this module. |
107 | model, you should *not* use this module. |
103 | |
108 | |
104 | DESCRIPTION |
109 | DESCRIPTION |
105 | AnyEvent provides an identical interface to multiple event loops. This |
110 | AnyEvent provides a uniform interface to various event loops. This |
106 | allows module authors to utilise an event loop without forcing module |
111 | allows module authors to use event loop functionality without forcing |
107 | users to use the same event loop (as only a single event loop can |
112 | module users to use a specific event loop implementation (since more |
108 | coexist peacefully at any one time). |
113 | than one event loop cannot coexist peacefully). |
109 | |
114 | |
110 | The interface itself is vaguely similar, but not identical to the Event |
115 | The interface itself is vaguely similar, but not identical to the Event |
111 | module. |
116 | module. |
112 | |
117 | |
113 | During the first call of any watcher-creation method, the module tries |
118 | During the first call of any watcher-creation method, the module tries |
114 | to detect the currently loaded event loop by probing whether one of the |
119 | to detect the currently loaded event loop by probing whether one of the |
115 | following modules is already loaded: EV, Event, Glib, |
120 | following modules is already loaded: EV, AnyEvent::Impl::Perl, Event, |
116 | AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found is |
121 | Glib, Tk, Event::Lib, Qt, POE. The first one found is used. If none are |
117 | used. If none are found, the module tries to load these modules |
122 | detected, the module tries to load the first four modules in the order |
118 | (excluding Tk, Event::Lib, Qt and POE as the pure perl adaptor should |
123 | given; but note that if EV is not available, the pure-perl |
119 | always succeed) in the order given. The first one that can be |
124 | AnyEvent::Impl::Perl should always work, so the other two are not |
120 | successfully loaded will be used. If, after this, still none could be |
125 | normally tried. |
121 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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122 | very efficient, but should work everywhere. |
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123 | |
126 | |
124 | Because AnyEvent first checks for modules that are already loaded, |
127 | Because AnyEvent first checks for modules that are already loaded, |
125 | loading an event model explicitly before first using AnyEvent will |
128 | loading an event model explicitly before first using AnyEvent will |
126 | likely make that model the default. For example: |
129 | likely make that model the default. For example: |
127 | |
130 | |
… | |
… | |
129 | use AnyEvent; |
132 | use AnyEvent; |
130 | |
133 | |
131 | # .. AnyEvent will likely default to Tk |
134 | # .. AnyEvent will likely default to Tk |
132 | |
135 | |
133 | The *likely* means that, if any module loads another event model and |
136 | The *likely* means that, if any module loads another event model and |
134 | starts using it, all bets are off. Maybe you should tell their authors |
137 | starts using it, all bets are off - this case should be very rare |
135 | to use AnyEvent so their modules work together with others seamlessly... |
138 | though, as very few modules hardcode event loops without announcing this |
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139 | very loudly. |
136 | |
140 | |
137 | The pure-perl implementation of AnyEvent is called |
141 | The pure-perl implementation of AnyEvent is called |
138 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
142 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
139 | explicitly and enjoy the high availability of that event loop :) |
143 | explicitly and enjoy the high availability of that event loop :) |
140 | |
144 | |
… | |
… | |
148 | callback when the event occurs (of course, only when the event model is |
152 | callback when the event occurs (of course, only when the event model is |
149 | in control). |
153 | in control). |
150 | |
154 | |
151 | Note that callbacks must not permanently change global variables |
155 | Note that callbacks must not permanently change global variables |
152 | potentially in use by the event loop (such as $_ or $[) and that |
156 | potentially in use by the event loop (such as $_ or $[) and that |
153 | callbacks must not "die". The former is good programming practise in |
157 | callbacks must not "die". The former is good programming practice in |
154 | Perl and the latter stems from the fact that exception handling differs |
158 | Perl and the latter stems from the fact that exception handling differs |
155 | widely between event loops. |
159 | widely between event loops. |
156 | |
160 | |
157 | To disable the watcher you have to destroy it (e.g. by setting the |
161 | To disable a watcher you have to destroy it (e.g. by setting the |
158 | variable you store it in to "undef" or otherwise deleting all references |
162 | variable you store it in to "undef" or otherwise deleting all references |
159 | to it). |
163 | to it). |
160 | |
164 | |
161 | All watchers are created by calling a method on the "AnyEvent" class. |
165 | All watchers are created by calling a method on the "AnyEvent" class. |
162 | |
166 | |
163 | Many watchers either are used with "recursion" (repeating timers for |
167 | Many watchers either are used with "recursion" (repeating timers for |
164 | example), or need to refer to their watcher object in other ways. |
168 | example), or need to refer to their watcher object in other ways. |
165 | |
169 | |
166 | An any way to achieve that is this pattern: |
170 | One way to achieve that is this pattern: |
167 | |
171 | |
168 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
172 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
169 | # you can use $w here, for example to undef it |
173 | # you can use $w here, for example to undef it |
170 | undef $w; |
174 | undef $w; |
171 | }); |
175 | }); |
… | |
… | |
202 | |
206 | |
203 | The I/O watcher might use the underlying file descriptor or a copy of |
207 | The I/O watcher might use the underlying file descriptor or a copy of |
204 | it. You must not close a file handle as long as any watcher is active on |
208 | it. You must not close a file handle as long as any watcher is active on |
205 | the underlying file descriptor. |
209 | the underlying file descriptor. |
206 | |
210 | |
207 | Some event loops issue spurious readyness notifications, so you should |
211 | Some event loops issue spurious readiness notifications, so you should |
208 | always use non-blocking calls when reading/writing from/to your file |
212 | always use non-blocking calls when reading/writing from/to your file |
209 | handles. |
213 | handles. |
210 | |
214 | |
211 | Example: wait for readability of STDIN, then read a line and disable the |
215 | Example: wait for readability of STDIN, then read a line and disable the |
212 | watcher. |
216 | watcher. |
… | |
… | |
235 | |
239 | |
236 | Although the callback might get passed parameters, their value and |
240 | Although the callback might get passed parameters, their value and |
237 | presence is undefined and you cannot rely on them. Portable AnyEvent |
241 | presence is undefined and you cannot rely on them. Portable AnyEvent |
238 | callbacks cannot use arguments passed to time watcher callbacks. |
242 | callbacks cannot use arguments passed to time watcher callbacks. |
239 | |
243 | |
240 | The callback will normally be invoked once only. If you specify another |
244 | The callback will normally be invoked only once. If you specify another |
241 | parameter, "interval", as a strictly positive number (> 0), then the |
245 | parameter, "interval", as a strictly positive number (> 0), then the |
242 | callback will be invoked regularly at that interval (in fractional |
246 | callback will be invoked regularly at that interval (in fractional |
243 | seconds) after the first invocation. If "interval" is specified with a |
247 | seconds) after the first invocation. If "interval" is specified with a |
244 | false value, then it is treated as if it were missing. |
248 | false value, then it is treated as if it were not specified at all. |
245 | |
249 | |
246 | The callback will be rescheduled before invoking the callback, but no |
250 | The callback will be rescheduled before invoking the callback, but no |
247 | attempt is done to avoid timer drift in most backends, so the interval |
251 | attempt is made to avoid timer drift in most backends, so the interval |
248 | is only approximate. |
252 | is only approximate. |
249 | |
253 | |
250 | Example: fire an event after 7.7 seconds. |
254 | Example: fire an event after 7.7 seconds. |
251 | |
255 | |
252 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
256 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
… | |
… | |
269 | |
273 | |
270 | While most event loops expect timers to specified in a relative way, |
274 | While most event loops expect timers to specified in a relative way, |
271 | they use absolute time internally. This makes a difference when your |
275 | they use absolute time internally. This makes a difference when your |
272 | clock "jumps", for example, when ntp decides to set your clock backwards |
276 | clock "jumps", for example, when ntp decides to set your clock backwards |
273 | from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is |
277 | from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is |
274 | supposed to fire "after" a second might actually take six years to |
278 | supposed to fire "after a second" might actually take six years to |
275 | finally fire. |
279 | finally fire. |
276 | |
280 | |
277 | AnyEvent cannot compensate for this. The only event loop that is |
281 | AnyEvent cannot compensate for this. The only event loop that is |
278 | conscious about these issues is EV, which offers both relative |
282 | conscious of these issues is EV, which offers both relative (ev_timer, |
279 | (ev_timer, based on true relative time) and absolute (ev_periodic, based |
283 | based on true relative time) and absolute (ev_periodic, based on |
280 | on wallclock time) timers. |
284 | wallclock time) timers. |
281 | |
285 | |
282 | AnyEvent always prefers relative timers, if available, matching the |
286 | AnyEvent always prefers relative timers, if available, matching the |
283 | AnyEvent API. |
287 | AnyEvent API. |
284 | |
288 | |
285 | AnyEvent has two additional methods that return the "current time": |
289 | AnyEvent has two additional methods that return the "current time": |
… | |
… | |
304 | *In almost all cases (in all cases if you don't care), this is the |
308 | *In almost all cases (in all cases if you don't care), this is the |
305 | function to call when you want to know the current time.* |
309 | function to call when you want to know the current time.* |
306 | |
310 | |
307 | This function is also often faster then "AnyEvent->time", and thus |
311 | This function is also often faster then "AnyEvent->time", and thus |
308 | the preferred method if you want some timestamp (for example, |
312 | the preferred method if you want some timestamp (for example, |
309 | AnyEvent::Handle uses this to update it's activity timeouts). |
313 | AnyEvent::Handle uses this to update its activity timeouts). |
310 | |
314 | |
311 | The rest of this section is only of relevance if you try to be very |
315 | The rest of this section is only of relevance if you try to be very |
312 | exact with your timing, you can skip it without bad conscience. |
316 | exact with your timing; you can skip it without a bad conscience. |
313 | |
317 | |
314 | For a practical example of when these times differ, consider |
318 | For a practical example of when these times differ, consider |
315 | Event::Lib and EV and the following set-up: |
319 | Event::Lib and EV and the following set-up: |
316 | |
320 | |
317 | The event loop is running and has just invoked one of your callback |
321 | The event loop is running and has just invoked one of your callbacks |
318 | at time=500 (assume no other callbacks delay processing). In your |
322 | at time=500 (assume no other callbacks delay processing). In your |
319 | callback, you wait a second by executing "sleep 1" (blocking the |
323 | callback, you wait a second by executing "sleep 1" (blocking the |
320 | process for a second) and then (at time=501) you create a relative |
324 | process for a second) and then (at time=501) you create a relative |
321 | timer that fires after three seconds. |
325 | timer that fires after three seconds. |
322 | |
326 | |
… | |
… | |
354 | time, which might affect timers and time-outs. |
358 | time, which might affect timers and time-outs. |
355 | |
359 | |
356 | When this is the case, you can call this method, which will update |
360 | When this is the case, you can call this method, which will update |
357 | the event loop's idea of "current time". |
361 | the event loop's idea of "current time". |
358 | |
362 | |
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363 | A typical example would be a script in a web server (e.g. |
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364 | "mod_perl") - when mod_perl executes the script, then the event loop |
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365 | will have the wrong idea about the "current time" (being potentially |
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366 | far in the past, when the script ran the last time). In that case |
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367 | you should arrange a call to "AnyEvent->now_update" each time the |
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368 | web server process wakes up again (e.g. at the start of your script, |
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369 | or in a handler). |
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370 | |
359 | Note that updating the time *might* cause some events to be handled. |
371 | Note that updating the time *might* cause some events to be handled. |
360 | |
372 | |
361 | SIGNAL WATCHERS |
373 | SIGNAL WATCHERS |
362 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
374 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
363 | |
375 | |
… | |
… | |
384 | |
396 | |
385 | Example: exit on SIGINT |
397 | Example: exit on SIGINT |
386 | |
398 | |
387 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
399 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
388 | |
400 | |
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401 | Restart Behaviour |
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402 | While restart behaviour is up to the event loop implementation, most |
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403 | will not restart syscalls (that includes Async::Interrupt and AnyEvent's |
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404 | pure perl implementation). |
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405 | |
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406 | Safe/Unsafe Signals |
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407 | Perl signals can be either "safe" (synchronous to opcode handling) or |
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408 | "unsafe" (asynchronous) - the former might get delayed indefinitely, the |
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409 | latter might corrupt your memory. |
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410 | |
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411 | AnyEvent signal handlers are, in addition, synchronous to the event |
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412 | loop, i.e. they will not interrupt your running perl program but will |
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413 | only be called as part of the normal event handling (just like timer, |
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414 | I/O etc. callbacks, too). |
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415 | |
389 | Signal Races, Delays and Workarounds |
416 | Signal Races, Delays and Workarounds |
390 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
417 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
391 | callbacks to signals in a generic way, which is a pity, as you cannot do |
418 | callbacks to signals in a generic way, which is a pity, as you cannot do |
392 | race-free signal handling in perl, requiring C libraries for this. |
419 | race-free signal handling in perl, requiring C libraries for this. |
393 | AnyEvent will try to do it's best, which means in some cases, signals |
420 | AnyEvent will try to do its best, which means in some cases, signals |
394 | will be delayed. The maximum time a signal might be delayed is specified |
421 | will be delayed. The maximum time a signal might be delayed is specified |
395 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
422 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
396 | can be changed only before the first signal watcher is created, and |
423 | can be changed only before the first signal watcher is created, and |
397 | should be left alone otherwise. This variable determines how often |
424 | should be left alone otherwise. This variable determines how often |
398 | AnyEvent polls for signals (in case a wake-up was missed). Higher values |
425 | AnyEvent polls for signals (in case a wake-up was missed). Higher values |
… | |
… | |
400 | saving. |
427 | saving. |
401 | |
428 | |
402 | All these problems can be avoided by installing the optional |
429 | All these problems can be avoided by installing the optional |
403 | Async::Interrupt module, which works with most event loops. It will not |
430 | Async::Interrupt module, which works with most event loops. It will not |
404 | work with inherently broken event loops such as Event or Event::Lib (and |
431 | work with inherently broken event loops such as Event or Event::Lib (and |
405 | not with POE currently, as POE does it's own workaround with one-second |
432 | not with POE currently, as POE does its own workaround with one-second |
406 | latency). For those, you just have to suffer the delays. |
433 | latency). For those, you just have to suffer the delays. |
407 | |
434 | |
408 | CHILD PROCESS WATCHERS |
435 | CHILD PROCESS WATCHERS |
409 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
436 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
410 | |
437 | |
411 | You can also watch on a child process exit and catch its exit status. |
438 | You can also watch for a child process exit and catch its exit status. |
412 | |
439 | |
413 | The child process is specified by the "pid" argument (one some backends, |
440 | The child process is specified by the "pid" argument (on some backends, |
414 | using 0 watches for any child process exit, on others this will croak). |
441 | using 0 watches for any child process exit, on others this will croak). |
415 | The watcher will be triggered only when the child process has finished |
442 | The watcher will be triggered only when the child process has finished |
416 | and an exit status is available, not on any trace events |
443 | and an exit status is available, not on any trace events |
417 | (stopped/continued). |
444 | (stopped/continued). |
418 | |
445 | |
… | |
… | |
463 | $done->recv; |
490 | $done->recv; |
464 | |
491 | |
465 | IDLE WATCHERS |
492 | IDLE WATCHERS |
466 | $w = AnyEvent->idle (cb => <callback>); |
493 | $w = AnyEvent->idle (cb => <callback>); |
467 | |
494 | |
468 | Sometimes there is a need to do something, but it is not so important to |
495 | This will repeatedly invoke the callback after the process becomes idle, |
469 | do it instantly, but only when there is nothing better to do. This |
496 | until either the watcher is destroyed or new events have been detected. |
470 | "nothing better to do" is usually defined to be "no other events need |
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471 | attention by the event loop". |
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472 | |
497 | |
473 | Idle watchers ideally get invoked when the event loop has nothing better |
498 | Idle watchers are useful when there is a need to do something, but it is |
474 | to do, just before it would block the process to wait for new events. |
499 | not so important (or wise) to do it instantly. The callback will be |
475 | Instead of blocking, the idle watcher is invoked. |
500 | invoked only when there is "nothing better to do", which is usually |
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501 | defined as "all outstanding events have been handled and no new events |
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502 | have been detected". That means that idle watchers ideally get invoked |
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503 | when the event loop has just polled for new events but none have been |
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504 | detected. Instead of blocking to wait for more events, the idle watchers |
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505 | will be invoked. |
476 | |
506 | |
477 | Most event loops unfortunately do not really support idle watchers (only |
507 | Unfortunately, most event loops do not really support idle watchers |
478 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
508 | (only EV, Event and Glib do it in a usable fashion) - for the rest, |
479 | will simply call the callback "from time to time". |
509 | AnyEvent will simply call the callback "from time to time". |
480 | |
510 | |
481 | Example: read lines from STDIN, but only process them when the program |
511 | Example: read lines from STDIN, but only process them when the program |
482 | is otherwise idle: |
512 | is otherwise idle: |
483 | |
513 | |
484 | my @lines; # read data |
514 | my @lines; # read data |
… | |
… | |
510 | |
540 | |
511 | AnyEvent is slightly different: it expects somebody else to run the |
541 | AnyEvent is slightly different: it expects somebody else to run the |
512 | event loop and will only block when necessary (usually when told by the |
542 | event loop and will only block when necessary (usually when told by the |
513 | user). |
543 | user). |
514 | |
544 | |
515 | The instrument to do that is called a "condition variable", so called |
545 | The tool to do that is called a "condition variable", so called because |
516 | because they represent a condition that must become true. |
546 | they represent a condition that must become true. |
517 | |
547 | |
518 | Now is probably a good time to look at the examples further below. |
548 | Now is probably a good time to look at the examples further below. |
519 | |
549 | |
520 | Condition variables can be created by calling the "AnyEvent->condvar" |
550 | Condition variables can be created by calling the "AnyEvent->condvar" |
521 | method, usually without arguments. The only argument pair allowed is |
551 | method, usually without arguments. The only argument pair allowed is |
… | |
… | |
526 | After creation, the condition variable is "false" until it becomes |
556 | After creation, the condition variable is "false" until it becomes |
527 | "true" by calling the "send" method (or calling the condition variable |
557 | "true" by calling the "send" method (or calling the condition variable |
528 | as if it were a callback, read about the caveats in the description for |
558 | as if it were a callback, read about the caveats in the description for |
529 | the "->send" method). |
559 | the "->send" method). |
530 | |
560 | |
531 | Condition variables are similar to callbacks, except that you can |
561 | Since condition variables are the most complex part of the AnyEvent API, |
532 | optionally wait for them. They can also be called merge points - points |
562 | here are some different mental models of what they are - pick the ones |
533 | in time where multiple outstanding events have been processed. And yet |
563 | you can connect to: |
534 | another way to call them is transactions - each condition variable can |
564 | |
535 | be used to represent a transaction, which finishes at some point and |
565 | * Condition variables are like callbacks - you can call them (and pass |
536 | delivers a result. And yet some people know them as "futures" - a |
566 | them instead of callbacks). Unlike callbacks however, you can also |
537 | promise to compute/deliver something that you can wait for. |
567 | wait for them to be called. |
|
|
568 | |
|
|
569 | * Condition variables are signals - one side can emit or send them, |
|
|
570 | the other side can wait for them, or install a handler that is |
|
|
571 | called when the signal fires. |
|
|
572 | |
|
|
573 | * Condition variables are like "Merge Points" - points in your program |
|
|
574 | where you merge multiple independent results/control flows into one. |
|
|
575 | |
|
|
576 | * Condition variables represent a transaction - functions that start |
|
|
577 | some kind of transaction can return them, leaving the caller the |
|
|
578 | choice between waiting in a blocking fashion, or setting a callback. |
|
|
579 | |
|
|
580 | * Condition variables represent future values, or promises to deliver |
|
|
581 | some result, long before the result is available. |
538 | |
582 | |
539 | Condition variables are very useful to signal that something has |
583 | Condition variables are very useful to signal that something has |
540 | finished, for example, if you write a module that does asynchronous http |
584 | finished, for example, if you write a module that does asynchronous http |
541 | requests, then a condition variable would be the ideal candidate to |
585 | requests, then a condition variable would be the ideal candidate to |
542 | signal the availability of results. The user can either act when the |
586 | signal the availability of results. The user can either act when the |
… | |
… | |
555 | |
599 | |
556 | Condition variables are represented by hash refs in perl, and the keys |
600 | Condition variables are represented by hash refs in perl, and the keys |
557 | used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy |
601 | used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy |
558 | (it is often useful to build your own transaction class on top of |
602 | (it is often useful to build your own transaction class on top of |
559 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
603 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
560 | it's "new" method in your own "new" method. |
604 | its "new" method in your own "new" method. |
561 | |
605 | |
562 | There are two "sides" to a condition variable - the "producer side" |
606 | There are two "sides" to a condition variable - the "producer side" |
563 | which eventually calls "-> send", and the "consumer side", which waits |
607 | which eventually calls "-> send", and the "consumer side", which waits |
564 | for the send to occur. |
608 | for the send to occur. |
565 | |
609 | |
566 | Example: wait for a timer. |
610 | Example: wait for a timer. |
567 | |
611 | |
568 | # wait till the result is ready |
612 | # condition: "wait till the timer is fired" |
569 | my $result_ready = AnyEvent->condvar; |
613 | my $timer_fired = AnyEvent->condvar; |
570 | |
614 | |
571 | # do something such as adding a timer |
615 | # create the timer - we could wait for, say |
572 | # or socket watcher the calls $result_ready->send |
616 | # a handle becomign ready, or even an |
573 | # when the "result" is ready. |
617 | # AnyEvent::HTTP request to finish, but |
574 | # in this case, we simply use a timer: |
618 | # in this case, we simply use a timer: |
575 | my $w = AnyEvent->timer ( |
619 | my $w = AnyEvent->timer ( |
576 | after => 1, |
620 | after => 1, |
577 | cb => sub { $result_ready->send }, |
621 | cb => sub { $timer_fired->send }, |
578 | ); |
622 | ); |
579 | |
623 | |
580 | # this "blocks" (while handling events) till the callback |
624 | # this "blocks" (while handling events) till the callback |
581 | # calls ->send |
625 | # calls ->send |
582 | $result_ready->recv; |
626 | $timer_fired->recv; |
583 | |
627 | |
584 | Example: wait for a timer, but take advantage of the fact that condition |
628 | Example: wait for a timer, but take advantage of the fact that condition |
585 | variables are also callable directly. |
629 | variables are also callable directly. |
586 | |
630 | |
587 | my $done = AnyEvent->condvar; |
631 | my $done = AnyEvent->condvar; |
… | |
… | |
625 | Condition variables are overloaded so one can call them directly (as |
669 | Condition variables are overloaded so one can call them directly (as |
626 | if they were a code reference). Calling them directly is the same as |
670 | if they were a code reference). Calling them directly is the same as |
627 | calling "send". |
671 | calling "send". |
628 | |
672 | |
629 | $cv->croak ($error) |
673 | $cv->croak ($error) |
630 | Similar to send, but causes all call's to "->recv" to invoke |
674 | Similar to send, but causes all calls to "->recv" to invoke |
631 | "Carp::croak" with the given error message/object/scalar. |
675 | "Carp::croak" with the given error message/object/scalar. |
632 | |
676 | |
633 | This can be used to signal any errors to the condition variable |
677 | This can be used to signal any errors to the condition variable |
634 | user/consumer. Doing it this way instead of calling "croak" directly |
678 | user/consumer. Doing it this way instead of calling "croak" directly |
635 | delays the error detetcion, but has the overwhelmign advantage that |
679 | delays the error detection, but has the overwhelming advantage that |
636 | it diagnoses the error at the place where the result is expected, |
680 | it diagnoses the error at the place where the result is expected, |
637 | and not deep in some event clalback without connection to the actual |
681 | and not deep in some event callback with no connection to the actual |
638 | code causing the problem. |
682 | code causing the problem. |
639 | |
683 | |
640 | $cv->begin ([group callback]) |
684 | $cv->begin ([group callback]) |
641 | $cv->end |
685 | $cv->end |
642 | These two methods can be used to combine many transactions/events |
686 | These two methods can be used to combine many transactions/events |
… | |
… | |
679 | there is one call to "begin", so the condvar waits for all calls to |
723 | there is one call to "begin", so the condvar waits for all calls to |
680 | "end" before sending. |
724 | "end" before sending. |
681 | |
725 | |
682 | The ping example mentioned above is slightly more complicated, as |
726 | The ping example mentioned above is slightly more complicated, as |
683 | the there are results to be passwd back, and the number of tasks |
727 | the there are results to be passwd back, and the number of tasks |
684 | that are begung can potentially be zero: |
728 | that are begun can potentially be zero: |
685 | |
729 | |
686 | my $cv = AnyEvent->condvar; |
730 | my $cv = AnyEvent->condvar; |
687 | |
731 | |
688 | my %result; |
732 | my %result; |
689 | $cv->begin (sub { shift->send (\%result) }); |
733 | $cv->begin (sub { shift->send (\%result) }); |
… | |
… | |
710 | callback to be called once the counter reaches 0, and second, it |
754 | callback to be called once the counter reaches 0, and second, it |
711 | ensures that "send" is called even when "no" hosts are being pinged |
755 | ensures that "send" is called even when "no" hosts are being pinged |
712 | (the loop doesn't execute once). |
756 | (the loop doesn't execute once). |
713 | |
757 | |
714 | This is the general pattern when you "fan out" into multiple (but |
758 | This is the general pattern when you "fan out" into multiple (but |
715 | potentially none) subrequests: use an outer "begin"/"end" pair to |
759 | potentially zero) subrequests: use an outer "begin"/"end" pair to |
716 | set the callback and ensure "end" is called at least once, and then, |
760 | set the callback and ensure "end" is called at least once, and then, |
717 | for each subrequest you start, call "begin" and for each subrequest |
761 | for each subrequest you start, call "begin" and for each subrequest |
718 | you finish, call "end". |
762 | you finish, call "end". |
719 | |
763 | |
720 | METHODS FOR CONSUMERS |
764 | METHODS FOR CONSUMERS |
721 | These methods should only be used by the consuming side, i.e. the code |
765 | These methods should only be used by the consuming side, i.e. the code |
722 | awaits the condition. |
766 | awaits the condition. |
723 | |
767 | |
724 | $cv->recv |
768 | $cv->recv |
725 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
769 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
726 | have been called on c<$cv>, while servicing other watchers normally. |
770 | have been called on $cv, while servicing other watchers normally. |
727 | |
771 | |
728 | You can only wait once on a condition - additional calls are valid |
772 | You can only wait once on a condition - additional calls are valid |
729 | but will return immediately. |
773 | but will return immediately. |
730 | |
774 | |
731 | If an error condition has been set by calling "->croak", then this |
775 | If an error condition has been set by calling "->croak", then this |
… | |
… | |
748 | example, by coupling condition variables with some kind of request |
792 | example, by coupling condition variables with some kind of request |
749 | results and supporting callbacks so the caller knows that getting |
793 | results and supporting callbacks so the caller knows that getting |
750 | the result will not block, while still supporting blocking waits if |
794 | the result will not block, while still supporting blocking waits if |
751 | the caller so desires). |
795 | the caller so desires). |
752 | |
796 | |
753 | You can ensure that "-recv" never blocks by setting a callback and |
797 | You can ensure that "->recv" never blocks by setting a callback and |
754 | only calling "->recv" from within that callback (or at a later |
798 | only calling "->recv" from within that callback (or at a later |
755 | time). This will work even when the event loop does not support |
799 | time). This will work even when the event loop does not support |
756 | blocking waits otherwise. |
800 | blocking waits otherwise. |
757 | |
801 | |
758 | $bool = $cv->ready |
802 | $bool = $cv->ready |
… | |
… | |
761 | |
805 | |
762 | $cb = $cv->cb ($cb->($cv)) |
806 | $cb = $cv->cb ($cb->($cv)) |
763 | This is a mutator function that returns the callback set and |
807 | This is a mutator function that returns the callback set and |
764 | optionally replaces it before doing so. |
808 | optionally replaces it before doing so. |
765 | |
809 | |
766 | The callback will be called when the condition becomes (or already |
810 | The callback will be called when the condition becomes "true", i.e. |
767 | was) "true", i.e. when "send" or "croak" are called (or were |
811 | when "send" or "croak" are called, with the only argument being the |
768 | called), with the only argument being the condition variable itself. |
812 | condition variable itself. If the condition is already true, the |
769 | Calling "recv" inside the callback or at any later time is |
813 | callback is called immediately when it is set. Calling "recv" inside |
770 | guaranteed not to block. |
814 | the callback or at any later time is guaranteed not to block. |
771 | |
815 | |
772 | SUPPORTED EVENT LOOPS/BACKENDS |
816 | SUPPORTED EVENT LOOPS/BACKENDS |
773 | The available backend classes are (every class has its own manpage): |
817 | The available backend classes are (every class has its own manpage): |
774 | |
818 | |
775 | Backends that are autoprobed when no other event loop can be found. |
819 | Backends that are autoprobed when no other event loop can be found. |
… | |
… | |
780 | |
824 | |
781 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
825 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
782 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
826 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
783 | |
827 | |
784 | Backends that are transparently being picked up when they are used. |
828 | Backends that are transparently being picked up when they are used. |
785 | These will be used when they are currently loaded when the first |
829 | These will be used if they are already loaded when the first watcher |
786 | watcher is created, in which case it is assumed that the application |
830 | is created, in which case it is assumed that the application is |
787 | is using them. This means that AnyEvent will automatically pick the |
831 | using them. This means that AnyEvent will automatically pick the |
788 | right backend when the main program loads an event module before |
832 | right backend when the main program loads an event module before |
789 | anything starts to create watchers. Nothing special needs to be done |
833 | anything starts to create watchers. Nothing special needs to be done |
790 | by the main program. |
834 | by the main program. |
791 | |
835 | |
792 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
836 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
793 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
837 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
794 | AnyEvent::Impl::Tk based on Tk, very broken. |
838 | AnyEvent::Impl::Tk based on Tk, very broken. |
795 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
839 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
796 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
840 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
797 | AnyEvent::Impl::Irssi used when running within irssi. |
841 | AnyEvent::Impl::Irssi used when running within irssi. |
|
|
842 | AnyEvent::Impl::IOAsync based on IO::Async. |
|
|
843 | AnyEvent::Impl::Cocoa based on Cocoa::EventLoop. |
798 | |
844 | |
799 | Backends with special needs. |
845 | Backends with special needs. |
800 | Qt requires the Qt::Application to be instantiated first, but will |
846 | Qt requires the Qt::Application to be instantiated first, but will |
801 | otherwise be picked up automatically. As long as the main program |
847 | otherwise be picked up automatically. As long as the main program |
802 | instantiates the application before any AnyEvent watchers are |
848 | instantiates the application before any AnyEvent watchers are |
803 | created, everything should just work. |
849 | created, everything should just work. |
804 | |
850 | |
805 | AnyEvent::Impl::Qt based on Qt. |
851 | AnyEvent::Impl::Qt based on Qt. |
806 | |
852 | |
807 | Support for IO::Async can only be partial, as it is too broken and |
|
|
808 | architecturally limited to even support the AnyEvent API. It also is |
|
|
809 | the only event loop that needs the loop to be set explicitly, so it |
|
|
810 | can only be used by a main program knowing about AnyEvent. See |
|
|
811 | AnyEvent::Impl::Async for the gory details. |
|
|
812 | |
|
|
813 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
814 | |
|
|
815 | Event loops that are indirectly supported via other backends. |
853 | Event loops that are indirectly supported via other backends. |
816 | Some event loops can be supported via other modules: |
854 | Some event loops can be supported via other modules: |
817 | |
855 | |
818 | There is no direct support for WxWidgets (Wx) or Prima. |
856 | There is no direct support for WxWidgets (Wx) or Prima. |
819 | |
857 | |
… | |
… | |
837 | Contains "undef" until the first watcher is being created, before |
875 | Contains "undef" until the first watcher is being created, before |
838 | the backend has been autodetected. |
876 | the backend has been autodetected. |
839 | |
877 | |
840 | Afterwards it contains the event model that is being used, which is |
878 | Afterwards it contains the event model that is being used, which is |
841 | the name of the Perl class implementing the model. This class is |
879 | the name of the Perl class implementing the model. This class is |
842 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
880 | usually one of the "AnyEvent::Impl::xxx" modules, but can be any |
843 | other class in the case AnyEvent has been extended at runtime (e.g. |
881 | other class in the case AnyEvent has been extended at runtime (e.g. |
844 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
882 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
845 | |
883 | |
846 | AnyEvent::detect |
884 | AnyEvent::detect |
847 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
885 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
848 | if necessary. You should only call this function right before you |
886 | if necessary. You should only call this function right before you |
849 | would have created an AnyEvent watcher anyway, that is, as late as |
887 | would have created an AnyEvent watcher anyway, that is, as late as |
850 | possible at runtime, and not e.g. while initialising of your module. |
888 | possible at runtime, and not e.g. during initialisation of your |
|
|
889 | module. |
851 | |
890 | |
852 | If you need to do some initialisation before AnyEvent watchers are |
891 | If you need to do some initialisation before AnyEvent watchers are |
853 | created, use "post_detect". |
892 | created, use "post_detect". |
854 | |
893 | |
855 | $guard = AnyEvent::post_detect { BLOCK } |
894 | $guard = AnyEvent::post_detect { BLOCK } |
856 | Arranges for the code block to be executed as soon as the event |
895 | Arranges for the code block to be executed as soon as the event |
857 | model is autodetected (or immediately if this has already happened). |
896 | model is autodetected (or immediately if that has already happened). |
858 | |
897 | |
859 | The block will be executed *after* the actual backend has been |
898 | The block will be executed *after* the actual backend has been |
860 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
899 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
861 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
900 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
862 | other initialisations - see the sources of AnyEvent::Strict or |
901 | other initialisations - see the sources of AnyEvent::Strict or |
… | |
… | |
871 | object that automatically removes the callback again when it is |
910 | object that automatically removes the callback again when it is |
872 | destroyed (or "undef" when the hook was immediately executed). See |
911 | destroyed (or "undef" when the hook was immediately executed). See |
873 | AnyEvent::AIO for a case where this is useful. |
912 | AnyEvent::AIO for a case where this is useful. |
874 | |
913 | |
875 | Example: Create a watcher for the IO::AIO module and store it in |
914 | Example: Create a watcher for the IO::AIO module and store it in |
876 | $WATCHER. Only do so after the event loop is initialised, though. |
915 | $WATCHER, but do so only do so after the event loop is initialised. |
877 | |
916 | |
878 | our WATCHER; |
917 | our WATCHER; |
879 | |
918 | |
880 | my $guard = AnyEvent::post_detect { |
919 | my $guard = AnyEvent::post_detect { |
881 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
920 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
… | |
… | |
888 | |
927 | |
889 | $WATCHER ||= $guard; |
928 | $WATCHER ||= $guard; |
890 | |
929 | |
891 | @AnyEvent::post_detect |
930 | @AnyEvent::post_detect |
892 | If there are any code references in this array (you can "push" to it |
931 | If there are any code references in this array (you can "push" to it |
893 | before or after loading AnyEvent), then they will called directly |
932 | before or after loading AnyEvent), then they will be called directly |
894 | after the event loop has been chosen. |
933 | after the event loop has been chosen. |
895 | |
934 | |
896 | You should check $AnyEvent::MODEL before adding to this array, |
935 | You should check $AnyEvent::MODEL before adding to this array, |
897 | though: if it is defined then the event loop has already been |
936 | though: if it is defined then the event loop has already been |
898 | detected, and the array will be ignored. |
937 | detected, and the array will be ignored. |
899 | |
938 | |
900 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
939 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
901 | allows it,as it takes care of these details. |
940 | allows it, as it takes care of these details. |
902 | |
941 | |
903 | This variable is mainly useful for modules that can do something |
942 | This variable is mainly useful for modules that can do something |
904 | useful when AnyEvent is used and thus want to know when it is |
943 | useful when AnyEvent is used and thus want to know when it is |
905 | initialised, but do not need to even load it by default. This array |
944 | initialised, but do not need to even load it by default. This array |
906 | provides the means to hook into AnyEvent passively, without loading |
945 | provides the means to hook into AnyEvent passively, without loading |
907 | it. |
946 | it. |
908 | |
947 | |
|
|
948 | Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used |
|
|
949 | together, you could put this into Coro (this is the actual code used |
|
|
950 | by Coro to accomplish this): |
|
|
951 | |
|
|
952 | if (defined $AnyEvent::MODEL) { |
|
|
953 | # AnyEvent already initialised, so load Coro::AnyEvent |
|
|
954 | require Coro::AnyEvent; |
|
|
955 | } else { |
|
|
956 | # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent |
|
|
957 | # as soon as it is |
|
|
958 | push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; |
|
|
959 | } |
|
|
960 | |
909 | WHAT TO DO IN A MODULE |
961 | WHAT TO DO IN A MODULE |
910 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
962 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
911 | freely, but you should not load a specific event module or rely on it. |
963 | freely, but you should not load a specific event module or rely on it. |
912 | |
964 | |
913 | Be careful when you create watchers in the module body - AnyEvent will |
965 | Be careful when you create watchers in the module body - AnyEvent will |
… | |
… | |
920 | stall the whole program, and the whole point of using events is to stay |
972 | stall the whole program, and the whole point of using events is to stay |
921 | interactive. |
973 | interactive. |
922 | |
974 | |
923 | It is fine, however, to call "->recv" when the user of your module |
975 | It is fine, however, to call "->recv" when the user of your module |
924 | requests it (i.e. if you create a http request object ad have a method |
976 | requests it (i.e. if you create a http request object ad have a method |
925 | called "results" that returns the results, it should call "->recv" |
977 | called "results" that returns the results, it may call "->recv" freely, |
926 | freely, as the user of your module knows what she is doing. always). |
978 | as the user of your module knows what she is doing. Always). |
927 | |
979 | |
928 | WHAT TO DO IN THE MAIN PROGRAM |
980 | WHAT TO DO IN THE MAIN PROGRAM |
929 | There will always be a single main program - the only place that should |
981 | There will always be a single main program - the only place that should |
930 | dictate which event model to use. |
982 | dictate which event model to use. |
931 | |
983 | |
932 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
984 | If the program is not event-based, it need not do anything special, even |
933 | do anything special (it does not need to be event-based) and let |
985 | when it depends on a module that uses an AnyEvent. If the program itself |
934 | AnyEvent decide which implementation to chose if some module relies on |
986 | uses AnyEvent, but does not care which event loop is used, all it needs |
935 | it. |
987 | to do is "use AnyEvent". In either case, AnyEvent will choose the best |
|
|
988 | available loop implementation. |
936 | |
989 | |
937 | If the main program relies on a specific event model - for example, in |
990 | If the main program relies on a specific event model - for example, in |
938 | Gtk2 programs you have to rely on the Glib module - you should load the |
991 | Gtk2 programs you have to rely on the Glib module - you should load the |
939 | event module before loading AnyEvent or any module that uses it: |
992 | event module before loading AnyEvent or any module that uses it: |
940 | generally speaking, you should load it as early as possible. The reason |
993 | generally speaking, you should load it as early as possible. The reason |
941 | is that modules might create watchers when they are loaded, and AnyEvent |
994 | is that modules might create watchers when they are loaded, and AnyEvent |
942 | will decide on the event model to use as soon as it creates watchers, |
995 | will decide on the event model to use as soon as it creates watchers, |
943 | and it might chose the wrong one unless you load the correct one |
996 | and it might choose the wrong one unless you load the correct one |
944 | yourself. |
997 | yourself. |
945 | |
998 | |
946 | You can chose to use a pure-perl implementation by loading the |
999 | You can chose to use a pure-perl implementation by loading the |
947 | "AnyEvent::Impl::Perl" module, which gives you similar behaviour |
1000 | "AnyEvent::Impl::Perl" module, which gives you similar behaviour |
948 | everywhere, but letting AnyEvent chose the model is generally better. |
1001 | everywhere, but letting AnyEvent chose the model is generally better. |
… | |
… | |
965 | |
1018 | |
966 | OTHER MODULES |
1019 | OTHER MODULES |
967 | The following is a non-exhaustive list of additional modules that use |
1020 | The following is a non-exhaustive list of additional modules that use |
968 | AnyEvent as a client and can therefore be mixed easily with other |
1021 | AnyEvent as a client and can therefore be mixed easily with other |
969 | AnyEvent modules and other event loops in the same program. Some of the |
1022 | AnyEvent modules and other event loops in the same program. Some of the |
970 | modules come with AnyEvent, most are available via CPAN. |
1023 | modules come as part of AnyEvent, the others are available via CPAN. |
971 | |
1024 | |
972 | AnyEvent::Util |
1025 | AnyEvent::Util |
973 | Contains various utility functions that replace often-used but |
1026 | Contains various utility functions that replace often-used blocking |
974 | blocking functions such as "inet_aton" by event-/callback-based |
1027 | functions such as "inet_aton" with event/callback-based versions. |
975 | versions. |
|
|
976 | |
1028 | |
977 | AnyEvent::Socket |
1029 | AnyEvent::Socket |
978 | Provides various utility functions for (internet protocol) sockets, |
1030 | Provides various utility functions for (internet protocol) sockets, |
979 | addresses and name resolution. Also functions to create non-blocking |
1031 | addresses and name resolution. Also functions to create non-blocking |
980 | tcp connections or tcp servers, with IPv6 and SRV record support and |
1032 | tcp connections or tcp servers, with IPv6 and SRV record support and |
981 | more. |
1033 | more. |
982 | |
1034 | |
983 | AnyEvent::Handle |
1035 | AnyEvent::Handle |
984 | Provide read and write buffers, manages watchers for reads and |
1036 | Provide read and write buffers, manages watchers for reads and |
985 | writes, supports raw and formatted I/O, I/O queued and fully |
1037 | writes, supports raw and formatted I/O, I/O queued and fully |
986 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
1038 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS). |
987 | |
1039 | |
988 | AnyEvent::DNS |
1040 | AnyEvent::DNS |
989 | Provides rich asynchronous DNS resolver capabilities. |
1041 | Provides rich asynchronous DNS resolver capabilities. |
990 | |
1042 | |
|
|
1043 | AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, |
|
|
1044 | AnyEvent::IGS, AnyEvent::FCP |
|
|
1045 | Implement event-based interfaces to the protocols of the same name |
|
|
1046 | (for the curious, IGS is the International Go Server and FCP is the |
|
|
1047 | Freenet Client Protocol). |
|
|
1048 | |
|
|
1049 | AnyEvent::Handle::UDP |
|
|
1050 | Here be danger! |
|
|
1051 | |
|
|
1052 | As Pauli would put it, "Not only is it not right, it's not even |
|
|
1053 | wrong!" - there are so many things wrong with AnyEvent::Handle::UDP, |
|
|
1054 | most notably its use of a stream-based API with a protocol that |
|
|
1055 | isn't streamable, that the only way to improve it is to delete it. |
|
|
1056 | |
|
|
1057 | It features data corruption (but typically only under load) and |
|
|
1058 | general confusion. On top, the author is not only clueless about UDP |
|
|
1059 | but also fact-resistant - some gems of his understanding: "connect |
|
|
1060 | doesn't work with UDP", "UDP packets are not IP packets", "UDP only |
|
|
1061 | has datagrams, not packets", "I don't need to implement proper error |
|
|
1062 | checking as UDP doesn't support error checking" and so on - he |
|
|
1063 | doesn't even understand what's wrong with his module when it is |
|
|
1064 | explained to him. |
|
|
1065 | |
991 | AnyEvent::HTTP |
1066 | AnyEvent::DBI |
992 | A simple-to-use HTTP library that is capable of making a lot of |
1067 | Executes DBI requests asynchronously in a proxy process for you, |
993 | concurrent HTTP requests. |
1068 | notifying you in an event-based way when the operation is finished. |
|
|
1069 | |
|
|
1070 | AnyEvent::AIO |
|
|
1071 | Truly asynchronous (as opposed to non-blocking) I/O, should be in |
|
|
1072 | the toolbox of every event programmer. AnyEvent::AIO transparently |
|
|
1073 | fuses IO::AIO and AnyEvent together, giving AnyEvent access to |
|
|
1074 | event-based file I/O, and much more. |
994 | |
1075 | |
995 | AnyEvent::HTTPD |
1076 | AnyEvent::HTTPD |
996 | Provides a simple web application server framework. |
1077 | A simple embedded webserver. |
997 | |
1078 | |
998 | AnyEvent::FastPing |
1079 | AnyEvent::FastPing |
999 | The fastest ping in the west. |
1080 | The fastest ping in the west. |
1000 | |
|
|
1001 | AnyEvent::DBI |
|
|
1002 | Executes DBI requests asynchronously in a proxy process. |
|
|
1003 | |
|
|
1004 | AnyEvent::AIO |
|
|
1005 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
1006 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
1007 | together. |
|
|
1008 | |
|
|
1009 | AnyEvent::BDB |
|
|
1010 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
1011 | fuses BDB and AnyEvent together. |
|
|
1012 | |
|
|
1013 | AnyEvent::GPSD |
|
|
1014 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
1015 | information. |
|
|
1016 | |
|
|
1017 | AnyEvent::IRC |
|
|
1018 | AnyEvent based IRC client module family (replacing the older |
|
|
1019 | Net::IRC3). |
|
|
1020 | |
|
|
1021 | AnyEvent::XMPP |
|
|
1022 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
1023 | older Net::XMPP2>. |
|
|
1024 | |
|
|
1025 | AnyEvent::IGS |
|
|
1026 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
1027 | App::IGS). |
|
|
1028 | |
|
|
1029 | Net::FCP |
|
|
1030 | AnyEvent-based implementation of the Freenet Client Protocol, |
|
|
1031 | birthplace of AnyEvent. |
|
|
1032 | |
|
|
1033 | Event::ExecFlow |
|
|
1034 | High level API for event-based execution flow control. |
|
|
1035 | |
1081 | |
1036 | Coro |
1082 | Coro |
1037 | Has special support for AnyEvent via Coro::AnyEvent. |
1083 | Has special support for AnyEvent via Coro::AnyEvent. |
1038 | |
1084 | |
1039 | SIMPLIFIED AE API |
1085 | SIMPLIFIED AE API |
1040 | Starting with version 5.0, AnyEvent officially supports a second, much |
1086 | Starting with version 5.0, AnyEvent officially supports a second, much |
1041 | simpler, API that is designed to reduce the calling, typing and memory |
1087 | simpler, API that is designed to reduce the calling, typing and memory |
1042 | overhead. |
1088 | overhead by using function call syntax and a fixed number of parameters. |
1043 | |
1089 | |
1044 | See the AE manpage for details. |
1090 | See the AE manpage for details. |
1045 | |
1091 | |
1046 | ERROR AND EXCEPTION HANDLING |
1092 | ERROR AND EXCEPTION HANDLING |
1047 | In general, AnyEvent does not do any error handling - it relies on the |
1093 | In general, AnyEvent does not do any error handling - it relies on the |
… | |
… | |
1090 | thoroughly check the arguments passed to most method calls. If it |
1136 | thoroughly check the arguments passed to most method calls. If it |
1091 | finds any problems, it will croak. |
1137 | finds any problems, it will croak. |
1092 | |
1138 | |
1093 | In other words, enables "strict" mode. |
1139 | In other words, enables "strict" mode. |
1094 | |
1140 | |
1095 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
1141 | Unlike "use strict" (or its modern cousin, "use common::sense", it |
1096 | is definitely recommended to keep it off in production. Keeping |
1142 | is definitely recommended to keep it off in production. Keeping |
1097 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1143 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1098 | programs can be very useful, however. |
1144 | programs can be very useful, however. |
1099 | |
1145 | |
1100 | "PERL_ANYEVENT_MODEL" |
1146 | "PERL_ANYEVENT_MODEL" |
… | |
… | |
1312 | |
1358 | |
1313 | The actual code goes further and collects all errors ("die"s, |
1359 | The actual code goes further and collects all errors ("die"s, |
1314 | exceptions) that occurred during request processing. The "result" method |
1360 | exceptions) that occurred during request processing. The "result" method |
1315 | detects whether an exception as thrown (it is stored inside the $txn |
1361 | detects whether an exception as thrown (it is stored inside the $txn |
1316 | object) and just throws the exception, which means connection errors and |
1362 | object) and just throws the exception, which means connection errors and |
1317 | other problems get reported tot he code that tries to use the result, |
1363 | other problems get reported to the code that tries to use the result, |
1318 | not in a random callback. |
1364 | not in a random callback. |
1319 | |
1365 | |
1320 | All of this enables the following usage styles: |
1366 | All of this enables the following usage styles: |
1321 | |
1367 | |
1322 | 1. Blocking: |
1368 | 1. Blocking: |
… | |
… | |
1696 | |
1742 | |
1697 | Feel free to install your own handler, or reset it to defaults. |
1743 | Feel free to install your own handler, or reset it to defaults. |
1698 | |
1744 | |
1699 | RECOMMENDED/OPTIONAL MODULES |
1745 | RECOMMENDED/OPTIONAL MODULES |
1700 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
1746 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
1701 | it's built-in modules) are required to use it. |
1747 | its built-in modules) are required to use it. |
1702 | |
1748 | |
1703 | That does not mean that AnyEvent won't take advantage of some additional |
1749 | That does not mean that AnyEvent won't take advantage of some additional |
1704 | modules if they are installed. |
1750 | modules if they are installed. |
1705 | |
1751 | |
1706 | This section epxlains which additional modules will be used, and how |
1752 | This section explains which additional modules will be used, and how |
1707 | they affect AnyEvent's operetion. |
1753 | they affect AnyEvent's operation. |
1708 | |
1754 | |
1709 | Async::Interrupt |
1755 | Async::Interrupt |
1710 | This slightly arcane module is used to implement fast signal |
1756 | This slightly arcane module is used to implement fast signal |
1711 | handling: To my knowledge, there is no way to do completely |
1757 | handling: To my knowledge, there is no way to do completely |
1712 | race-free and quick signal handling in pure perl. To ensure that |
1758 | race-free and quick signal handling in pure perl. To ensure that |
… | |
… | |
1715 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
1761 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
1716 | |
1762 | |
1717 | If this module is available, then it will be used to implement |
1763 | If this module is available, then it will be used to implement |
1718 | signal catching, which means that signals will not be delayed, and |
1764 | signal catching, which means that signals will not be delayed, and |
1719 | the event loop will not be interrupted regularly, which is more |
1765 | the event loop will not be interrupted regularly, which is more |
1720 | efficient (And good for battery life on laptops). |
1766 | efficient (and good for battery life on laptops). |
1721 | |
1767 | |
1722 | This affects not just the pure-perl event loop, but also other event |
1768 | This affects not just the pure-perl event loop, but also other event |
1723 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
1769 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
1724 | |
1770 | |
1725 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
1771 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
… | |
… | |
1735 | clock is available, can take avdantage of advanced kernel interfaces |
1781 | clock is available, can take avdantage of advanced kernel interfaces |
1736 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
1782 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
1737 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
1783 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
1738 | Glib::EV). |
1784 | Glib::EV). |
1739 | |
1785 | |
|
|
1786 | If you only use backends that rely on another event loop (e.g. |
|
|
1787 | "Tk"), then this module will do nothing for you. |
|
|
1788 | |
1740 | Guard |
1789 | Guard |
1741 | The guard module, when used, will be used to implement |
1790 | The guard module, when used, will be used to implement |
1742 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
1791 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
1743 | uses a lot less memory), but otherwise doesn't affect guard |
1792 | uses a lot less memory), but otherwise doesn't affect guard |
1744 | operation much. It is purely used for performance. |
1793 | operation much. It is purely used for performance. |
1745 | |
1794 | |
1746 | JSON and JSON::XS |
1795 | JSON and JSON::XS |
1747 | This module is required when you want to read or write JSON data via |
1796 | One of these modules is required when you want to read or write JSON |
1748 | AnyEvent::Handle. It is also written in pure-perl, but can take |
1797 | data via AnyEvent::Handle. JSON is also written in pure-perl, but |
1749 | advantage of the ultra-high-speed JSON::XS module when it is |
1798 | can take advantage of the ultra-high-speed JSON::XS module when it |
1750 | installed. |
1799 | is installed. |
1751 | |
|
|
1752 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1753 | installed. |
|
|
1754 | |
1800 | |
1755 | Net::SSLeay |
1801 | Net::SSLeay |
1756 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
1802 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
1757 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
1803 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
1758 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
1804 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
1759 | |
1805 | |
1760 | Time::HiRes |
1806 | Time::HiRes |
1761 | This module is part of perl since release 5.008. It will be used |
1807 | This module is part of perl since release 5.008. It will be used |
1762 | when the chosen event library does not come with a timing source on |
1808 | when the chosen event library does not come with a timing source of |
1763 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
1809 | its own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
1764 | additionally use it to try to use a monotonic clock for timing |
1810 | additionally use it to try to use a monotonic clock for timing |
1765 | stability. |
1811 | stability. |
1766 | |
1812 | |
1767 | FORK |
1813 | FORK |
1768 | Most event libraries are not fork-safe. The ones who are usually are |
1814 | Most event libraries are not fork-safe. The ones who are usually are |
1769 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1815 | because they rely on inefficient but fork-safe "select" or "poll" calls |
1770 | Only EV is fully fork-aware. |
1816 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
|
|
1817 | epoll are usually badly thought-out hacks that are incompatible with |
|
|
1818 | fork in one way or another. Only EV is fully fork-aware and ensures that |
|
|
1819 | you continue event-processing in both parent and child (or both, if you |
|
|
1820 | know what you are doing). |
|
|
1821 | |
|
|
1822 | This means that, in general, you cannot fork and do event processing in |
|
|
1823 | the child if the event library was initialised before the fork (which |
|
|
1824 | usually happens when the first AnyEvent watcher is created, or the |
|
|
1825 | library is loaded). |
1771 | |
1826 | |
1772 | If you have to fork, you must either do so *before* creating your first |
1827 | If you have to fork, you must either do so *before* creating your first |
1773 | watcher OR you must not use AnyEvent at all in the child OR you must do |
1828 | watcher OR you must not use AnyEvent at all in the child OR you must do |
1774 | something completely out of the scope of AnyEvent. |
1829 | something completely out of the scope of AnyEvent. |
|
|
1830 | |
|
|
1831 | The problem of doing event processing in the parent *and* the child is |
|
|
1832 | much more complicated: even for backends that *are* fork-aware or |
|
|
1833 | fork-safe, their behaviour is not usually what you want: fork clones all |
|
|
1834 | watchers, that means all timers, I/O watchers etc. are active in both |
|
|
1835 | parent and child, which is almost never what you want. USing "exec" to |
|
|
1836 | start worker children from some kind of manage rprocess is usually |
|
|
1837 | preferred, because it is much easier and cleaner, at the expense of |
|
|
1838 | having to have another binary. |
1775 | |
1839 | |
1776 | SECURITY CONSIDERATIONS |
1840 | SECURITY CONSIDERATIONS |
1777 | AnyEvent can be forced to load any event model via |
1841 | AnyEvent can be forced to load any event model via |
1778 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1842 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1779 | to execute arbitrary code or directly gain access, it can easily be used |
1843 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1803 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1867 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1804 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1868 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1805 | not as pronounced). |
1869 | not as pronounced). |
1806 | |
1870 | |
1807 | SEE ALSO |
1871 | SEE ALSO |
|
|
1872 | Tutorial/Introduction: AnyEvent::Intro. |
|
|
1873 | |
|
|
1874 | FAQ: AnyEvent::FAQ. |
|
|
1875 | |
1808 | Utility functions: AnyEvent::Util. |
1876 | Utility functions: AnyEvent::Util. |
1809 | |
1877 | |
1810 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1878 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1811 | Event::Lib, Qt, POE. |
1879 | Event::Lib, Qt, POE. |
1812 | |
1880 | |
… | |
… | |
1818 | Non-blocking file handles, sockets, TCP clients and servers: |
1886 | Non-blocking file handles, sockets, TCP clients and servers: |
1819 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1887 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1820 | |
1888 | |
1821 | Asynchronous DNS: AnyEvent::DNS. |
1889 | Asynchronous DNS: AnyEvent::DNS. |
1822 | |
1890 | |
1823 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1891 | Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. |
1824 | |
1892 | |
1825 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
1893 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, |
1826 | AnyEvent::HTTP. |
1894 | AnyEvent::HTTP. |
1827 | |
1895 | |
1828 | AUTHOR |
1896 | AUTHOR |
1829 | Marc Lehmann <schmorp@schmorp.de> |
1897 | Marc Lehmann <schmorp@schmorp.de> |
1830 | http://home.schmorp.de/ |
1898 | http://home.schmorp.de/ |