1 | NAME |
1 | NAME |
2 | AnyEvent - the DBI of event loop programming |
2 | AnyEvent - the DBI of event loop programming |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, |
5 | Qt and POE are various supported event loops/environments. |
5 | Qt, FLTK and POE are various supported event loops/environments. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
|
|
10 | # if you prefer function calls, look at the AE manpage for |
|
|
11 | # an alternative API. |
|
|
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 |
|
|
47 | An FAQ document is available as AnyEvent::FAQ. |
|
|
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::Loop, Event, Glib, |
116 | AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found is |
121 | 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::Loop should always work, so the other two are not normally |
120 | successfully loaded will be used. If, after this, still none could be |
125 | tried. |
121 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
|
|
122 | very efficient, but should work everywhere. |
|
|
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 |
|
|
139 | very loudly. |
136 | |
140 | |
137 | The pure-perl implementation of AnyEvent is called |
141 | The pure-perl implementation of AnyEvent is called "AnyEvent::Loop". |
138 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
142 | Like other event modules you can load it explicitly and enjoy the high |
139 | explicitly and enjoy the high availability of that event loop :) |
143 | availability of that event loop :) |
140 | |
144 | |
141 | WATCHERS |
145 | WATCHERS |
142 | AnyEvent has the central concept of a *watcher*, which is an object that |
146 | AnyEvent has the central concept of a *watcher*, which is an object that |
143 | stores relevant data for each kind of event you are waiting for, such as |
147 | stores relevant data for each kind of event you are waiting for, such as |
144 | the callback to call, the file handle to watch, etc. |
148 | the callback to call, the file handle to watch, etc. |
… | |
… | |
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 | |
… | |
… | |
343 | can get whatever behaviour you want with any event loop, by taking |
347 | can get whatever behaviour you want with any event loop, by taking |
344 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
348 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
345 | account. |
349 | account. |
346 | |
350 | |
347 | AnyEvent->now_update |
351 | AnyEvent->now_update |
348 | Some event loops (such as EV or AnyEvent::Impl::Perl) cache the |
352 | Some event loops (such as EV or AnyEvent::Loop) cache the current |
349 | current time for each loop iteration (see the discussion of |
353 | time for each loop iteration (see the discussion of AnyEvent->now, |
350 | AnyEvent->now, above). |
354 | above). |
351 | |
355 | |
352 | When a callback runs for a long time (or when the process sleeps), |
356 | When a callback runs for a long time (or when the process sleeps), |
353 | then this "current" time will differ substantially from the real |
357 | then this "current" time will differ substantially from the real |
354 | time, which might affect timers and time-outs. |
358 | time, which might affect timers and time-outs. |
355 | |
359 | |
… | |
… | |
411 | |
415 | |
412 | Signal Races, Delays and Workarounds |
416 | Signal Races, Delays and Workarounds |
413 | 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 |
414 | 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 |
415 | race-free signal handling in perl, requiring C libraries for this. |
419 | race-free signal handling in perl, requiring C libraries for this. |
416 | 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 |
417 | 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 |
418 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
422 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
419 | 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 |
420 | should be left alone otherwise. This variable determines how often |
424 | should be left alone otherwise. This variable determines how often |
421 | 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 |
… | |
… | |
423 | saving. |
427 | saving. |
424 | |
428 | |
425 | All these problems can be avoided by installing the optional |
429 | All these problems can be avoided by installing the optional |
426 | 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 |
427 | 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 |
428 | 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 |
429 | latency). For those, you just have to suffer the delays. |
433 | latency). For those, you just have to suffer the delays. |
430 | |
434 | |
431 | CHILD PROCESS WATCHERS |
435 | CHILD PROCESS WATCHERS |
432 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
436 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
433 | |
437 | |
434 | 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. |
435 | |
439 | |
436 | 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, |
437 | 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). |
438 | 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 |
439 | and an exit status is available, not on any trace events |
443 | and an exit status is available, not on any trace events |
440 | (stopped/continued). |
444 | (stopped/continued). |
441 | |
445 | |
… | |
… | |
462 | This means you cannot create a child watcher as the very first thing in |
466 | This means you cannot create a child watcher as the very first thing in |
463 | an AnyEvent program, you *have* to create at least one watcher before |
467 | an AnyEvent program, you *have* to create at least one watcher before |
464 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
468 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
465 | |
469 | |
466 | As most event loops do not support waiting for child events, they will |
470 | As most event loops do not support waiting for child events, they will |
467 | be emulated by AnyEvent in most cases, in which the latency and race |
471 | be emulated by AnyEvent in most cases, in which case the latency and |
468 | problems mentioned in the description of signal watchers apply. |
472 | race problems mentioned in the description of signal watchers apply. |
469 | |
473 | |
470 | Example: fork a process and wait for it |
474 | Example: fork a process and wait for it |
471 | |
475 | |
472 | my $done = AnyEvent->condvar; |
476 | my $done = AnyEvent->condvar; |
473 | |
477 | |
… | |
… | |
486 | $done->recv; |
490 | $done->recv; |
487 | |
491 | |
488 | IDLE WATCHERS |
492 | IDLE WATCHERS |
489 | $w = AnyEvent->idle (cb => <callback>); |
493 | $w = AnyEvent->idle (cb => <callback>); |
490 | |
494 | |
491 | 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, |
492 | 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. |
493 | "nothing better to do" is usually defined to be "no other events need |
|
|
494 | attention by the event loop". |
|
|
495 | |
497 | |
496 | 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 |
497 | 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 |
498 | Instead of blocking, the idle watcher is invoked. |
500 | invoked only when there is "nothing better to do", which is usually |
|
|
501 | defined as "all outstanding events have been handled and no new events |
|
|
502 | have been detected". That means that idle watchers ideally get invoked |
|
|
503 | when the event loop has just polled for new events but none have been |
|
|
504 | detected. Instead of blocking to wait for more events, the idle watchers |
|
|
505 | will be invoked. |
499 | |
506 | |
500 | Most event loops unfortunately do not really support idle watchers (only |
507 | Unfortunately, most event loops do not really support idle watchers |
501 | 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, |
502 | will simply call the callback "from time to time". |
509 | AnyEvent will simply call the callback "from time to time". |
503 | |
510 | |
504 | 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 |
505 | is otherwise idle: |
512 | is otherwise idle: |
506 | |
513 | |
507 | my @lines; # read data |
514 | my @lines; # read data |
… | |
… | |
533 | |
540 | |
534 | AnyEvent is slightly different: it expects somebody else to run the |
541 | AnyEvent is slightly different: it expects somebody else to run the |
535 | 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 |
536 | user). |
543 | user). |
537 | |
544 | |
538 | 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 |
539 | because they represent a condition that must become true. |
546 | they represent a condition that must become true. |
540 | |
547 | |
541 | 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. |
542 | |
549 | |
543 | Condition variables can be created by calling the "AnyEvent->condvar" |
550 | Condition variables can be created by calling the "AnyEvent->condvar" |
544 | method, usually without arguments. The only argument pair allowed is |
551 | method, usually without arguments. The only argument pair allowed is |
… | |
… | |
549 | After creation, the condition variable is "false" until it becomes |
556 | After creation, the condition variable is "false" until it becomes |
550 | "true" by calling the "send" method (or calling the condition variable |
557 | "true" by calling the "send" method (or calling the condition variable |
551 | 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 |
552 | the "->send" method). |
559 | the "->send" method). |
553 | |
560 | |
554 | Condition variables are similar to callbacks, except that you can |
561 | Since condition variables are the most complex part of the AnyEvent API, |
555 | 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 |
556 | in time where multiple outstanding events have been processed. And yet |
563 | you can connect to: |
557 | another way to call them is transactions - each condition variable can |
564 | |
558 | be used to represent a transaction, which finishes at some point and |
565 | * Condition variables are like callbacks - you can call them (and pass |
559 | delivers a result. And yet some people know them as "futures" - a |
566 | them instead of callbacks). Unlike callbacks however, you can also |
560 | 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. |
561 | |
582 | |
562 | Condition variables are very useful to signal that something has |
583 | Condition variables are very useful to signal that something has |
563 | 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 |
564 | requests, then a condition variable would be the ideal candidate to |
585 | requests, then a condition variable would be the ideal candidate to |
565 | 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 |
… | |
… | |
578 | |
599 | |
579 | 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 |
580 | 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 |
581 | (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 |
582 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
603 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
583 | it's "new" method in your own "new" method. |
604 | its "new" method in your own "new" method. |
584 | |
605 | |
585 | There are two "sides" to a condition variable - the "producer side" |
606 | There are two "sides" to a condition variable - the "producer side" |
586 | which eventually calls "-> send", and the "consumer side", which waits |
607 | which eventually calls "-> send", and the "consumer side", which waits |
587 | for the send to occur. |
608 | for the send to occur. |
588 | |
609 | |
589 | Example: wait for a timer. |
610 | Example: wait for a timer. |
590 | |
611 | |
591 | # wait till the result is ready |
612 | # condition: "wait till the timer is fired" |
592 | my $result_ready = AnyEvent->condvar; |
613 | my $timer_fired = AnyEvent->condvar; |
593 | |
614 | |
594 | # do something such as adding a timer |
615 | # create the timer - we could wait for, say |
595 | # or socket watcher the calls $result_ready->send |
616 | # a handle becomign ready, or even an |
596 | # when the "result" is ready. |
617 | # AnyEvent::HTTP request to finish, but |
597 | # in this case, we simply use a timer: |
618 | # in this case, we simply use a timer: |
598 | my $w = AnyEvent->timer ( |
619 | my $w = AnyEvent->timer ( |
599 | after => 1, |
620 | after => 1, |
600 | cb => sub { $result_ready->send }, |
621 | cb => sub { $timer_fired->send }, |
601 | ); |
622 | ); |
602 | |
623 | |
603 | # this "blocks" (while handling events) till the callback |
624 | # this "blocks" (while handling events) till the callback |
604 | # calls ->send |
625 | # calls ->send |
605 | $result_ready->recv; |
626 | $timer_fired->recv; |
606 | |
627 | |
607 | 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 |
608 | variables are also callable directly. |
629 | variables are also callable directly. |
609 | |
630 | |
610 | my $done = AnyEvent->condvar; |
631 | my $done = AnyEvent->condvar; |
… | |
… | |
648 | Condition variables are overloaded so one can call them directly (as |
669 | Condition variables are overloaded so one can call them directly (as |
649 | 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 |
650 | calling "send". |
671 | calling "send". |
651 | |
672 | |
652 | $cv->croak ($error) |
673 | $cv->croak ($error) |
653 | Similar to send, but causes all call's to "->recv" to invoke |
674 | Similar to send, but causes all calls to "->recv" to invoke |
654 | "Carp::croak" with the given error message/object/scalar. |
675 | "Carp::croak" with the given error message/object/scalar. |
655 | |
676 | |
656 | 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 |
657 | user/consumer. Doing it this way instead of calling "croak" directly |
678 | user/consumer. Doing it this way instead of calling "croak" directly |
658 | delays the error detetcion, but has the overwhelmign advantage that |
679 | delays the error detection, but has the overwhelming advantage that |
659 | 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, |
660 | 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 |
661 | code causing the problem. |
682 | code causing the problem. |
662 | |
683 | |
663 | $cv->begin ([group callback]) |
684 | $cv->begin ([group callback]) |
664 | $cv->end |
685 | $cv->end |
665 | These two methods can be used to combine many transactions/events |
686 | These two methods can be used to combine many transactions/events |
… | |
… | |
702 | 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 |
703 | "end" before sending. |
724 | "end" before sending. |
704 | |
725 | |
705 | The ping example mentioned above is slightly more complicated, as |
726 | The ping example mentioned above is slightly more complicated, as |
706 | 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 |
707 | that are begung can potentially be zero: |
728 | that are begun can potentially be zero: |
708 | |
729 | |
709 | my $cv = AnyEvent->condvar; |
730 | my $cv = AnyEvent->condvar; |
710 | |
731 | |
711 | my %result; |
732 | my %result; |
712 | $cv->begin (sub { shift->send (\%result) }); |
733 | $cv->begin (sub { shift->send (\%result) }); |
… | |
… | |
733 | 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 |
734 | 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 |
735 | (the loop doesn't execute once). |
756 | (the loop doesn't execute once). |
736 | |
757 | |
737 | 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 |
738 | potentially none) subrequests: use an outer "begin"/"end" pair to |
759 | potentially zero) subrequests: use an outer "begin"/"end" pair to |
739 | 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, |
740 | for each subrequest you start, call "begin" and for each subrequest |
761 | for each subrequest you start, call "begin" and for each subrequest |
741 | you finish, call "end". |
762 | you finish, call "end". |
742 | |
763 | |
743 | METHODS FOR CONSUMERS |
764 | METHODS FOR CONSUMERS |
744 | 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 |
745 | awaits the condition. |
766 | awaits the condition. |
746 | |
767 | |
747 | $cv->recv |
768 | $cv->recv |
748 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
769 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
749 | have been called on c<$cv>, while servicing other watchers normally. |
770 | have been called on $cv, while servicing other watchers normally. |
750 | |
771 | |
751 | 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 |
752 | but will return immediately. |
773 | but will return immediately. |
753 | |
774 | |
754 | 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 |
… | |
… | |
771 | example, by coupling condition variables with some kind of request |
792 | example, by coupling condition variables with some kind of request |
772 | results and supporting callbacks so the caller knows that getting |
793 | results and supporting callbacks so the caller knows that getting |
773 | the result will not block, while still supporting blocking waits if |
794 | the result will not block, while still supporting blocking waits if |
774 | the caller so desires). |
795 | the caller so desires). |
775 | |
796 | |
776 | 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 |
777 | only calling "->recv" from within that callback (or at a later |
798 | only calling "->recv" from within that callback (or at a later |
778 | 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 |
779 | blocking waits otherwise. |
800 | blocking waits otherwise. |
780 | |
801 | |
781 | $bool = $cv->ready |
802 | $bool = $cv->ready |
… | |
… | |
784 | |
805 | |
785 | $cb = $cv->cb ($cb->($cv)) |
806 | $cb = $cv->cb ($cb->($cv)) |
786 | This is a mutator function that returns the callback set and |
807 | This is a mutator function that returns the callback set and |
787 | optionally replaces it before doing so. |
808 | optionally replaces it before doing so. |
788 | |
809 | |
789 | The callback will be called when the condition becomes (or already |
810 | The callback will be called when the condition becomes "true", i.e. |
790 | 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 |
791 | called), with the only argument being the condition variable itself. |
812 | condition variable itself. If the condition is already true, the |
792 | Calling "recv" inside the callback or at any later time is |
813 | callback is called immediately when it is set. Calling "recv" inside |
793 | guaranteed not to block. |
814 | the callback or at any later time is guaranteed not to block. |
794 | |
815 | |
795 | SUPPORTED EVENT LOOPS/BACKENDS |
816 | SUPPORTED EVENT LOOPS/BACKENDS |
796 | The available backend classes are (every class has its own manpage): |
817 | The available backend classes are (every class has its own manpage): |
797 | |
818 | |
798 | 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. |
… | |
… | |
800 | use. If EV is not installed, then AnyEvent will fall back to its own |
821 | use. If EV is not installed, then AnyEvent will fall back to its own |
801 | pure-perl implementation, which is available everywhere as it comes |
822 | pure-perl implementation, which is available everywhere as it comes |
802 | with AnyEvent itself. |
823 | with AnyEvent itself. |
803 | |
824 | |
804 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
825 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
805 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
826 | AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable. |
806 | |
827 | |
807 | Backends that are transparently being picked up when they are used. |
828 | Backends that are transparently being picked up when they are used. |
808 | 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 |
809 | 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 |
810 | is using them. This means that AnyEvent will automatically pick the |
831 | using them. This means that AnyEvent will automatically pick the |
811 | right backend when the main program loads an event module before |
832 | right backend when the main program loads an event module before |
812 | anything starts to create watchers. Nothing special needs to be done |
833 | anything starts to create watchers. Nothing special needs to be done |
813 | by the main program. |
834 | by the main program. |
814 | |
835 | |
815 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
836 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
816 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
837 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
817 | AnyEvent::Impl::Tk based on Tk, very broken. |
838 | AnyEvent::Impl::Tk based on Tk, very broken. |
818 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
839 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
819 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
840 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
820 | 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. |
|
|
844 | AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding). |
821 | |
845 | |
822 | Backends with special needs. |
846 | Backends with special needs. |
823 | Qt requires the Qt::Application to be instantiated first, but will |
847 | Qt requires the Qt::Application to be instantiated first, but will |
824 | otherwise be picked up automatically. As long as the main program |
848 | otherwise be picked up automatically. As long as the main program |
825 | instantiates the application before any AnyEvent watchers are |
849 | instantiates the application before any AnyEvent watchers are |
826 | created, everything should just work. |
850 | created, everything should just work. |
827 | |
851 | |
828 | AnyEvent::Impl::Qt based on Qt. |
852 | AnyEvent::Impl::Qt based on Qt. |
829 | |
853 | |
830 | Support for IO::Async can only be partial, as it is too broken and |
|
|
831 | architecturally limited to even support the AnyEvent API. It also is |
|
|
832 | the only event loop that needs the loop to be set explicitly, so it |
|
|
833 | can only be used by a main program knowing about AnyEvent. See |
|
|
834 | AnyEvent::Impl::Async for the gory details. |
|
|
835 | |
|
|
836 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
837 | |
|
|
838 | Event loops that are indirectly supported via other backends. |
854 | Event loops that are indirectly supported via other backends. |
839 | Some event loops can be supported via other modules: |
855 | Some event loops can be supported via other modules: |
840 | |
856 | |
841 | There is no direct support for WxWidgets (Wx) or Prima. |
857 | There is no direct support for WxWidgets (Wx) or Prima. |
842 | |
858 | |
… | |
… | |
860 | Contains "undef" until the first watcher is being created, before |
876 | Contains "undef" until the first watcher is being created, before |
861 | the backend has been autodetected. |
877 | the backend has been autodetected. |
862 | |
878 | |
863 | Afterwards it contains the event model that is being used, which is |
879 | Afterwards it contains the event model that is being used, which is |
864 | the name of the Perl class implementing the model. This class is |
880 | the name of the Perl class implementing the model. This class is |
865 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
881 | usually one of the "AnyEvent::Impl::xxx" modules, but can be any |
866 | other class in the case AnyEvent has been extended at runtime (e.g. |
882 | other class in the case AnyEvent has been extended at runtime (e.g. |
867 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
883 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
868 | |
884 | |
869 | AnyEvent::detect |
885 | AnyEvent::detect |
870 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
886 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
871 | if necessary. You should only call this function right before you |
887 | if necessary. You should only call this function right before you |
872 | would have created an AnyEvent watcher anyway, that is, as late as |
888 | would have created an AnyEvent watcher anyway, that is, as late as |
873 | possible at runtime, and not e.g. while initialising of your module. |
889 | possible at runtime, and not e.g. during initialisation of your |
|
|
890 | module. |
|
|
891 | |
|
|
892 | The effect of calling this function is as if a watcher had been |
|
|
893 | created (specifically, actions that happen "when the first watcher |
|
|
894 | is created" happen when calling detetc as well). |
874 | |
895 | |
875 | If you need to do some initialisation before AnyEvent watchers are |
896 | If you need to do some initialisation before AnyEvent watchers are |
876 | created, use "post_detect". |
897 | created, use "post_detect". |
877 | |
898 | |
878 | $guard = AnyEvent::post_detect { BLOCK } |
899 | $guard = AnyEvent::post_detect { BLOCK } |
879 | Arranges for the code block to be executed as soon as the event |
900 | Arranges for the code block to be executed as soon as the event |
880 | model is autodetected (or immediately if this has already happened). |
901 | model is autodetected (or immediately if that has already happened). |
881 | |
902 | |
882 | The block will be executed *after* the actual backend has been |
903 | The block will be executed *after* the actual backend has been |
883 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
904 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
884 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
905 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
885 | other initialisations - see the sources of AnyEvent::Strict or |
906 | other initialisations - see the sources of AnyEvent::Strict or |
… | |
… | |
894 | object that automatically removes the callback again when it is |
915 | object that automatically removes the callback again when it is |
895 | destroyed (or "undef" when the hook was immediately executed). See |
916 | destroyed (or "undef" when the hook was immediately executed). See |
896 | AnyEvent::AIO for a case where this is useful. |
917 | AnyEvent::AIO for a case where this is useful. |
897 | |
918 | |
898 | Example: Create a watcher for the IO::AIO module and store it in |
919 | Example: Create a watcher for the IO::AIO module and store it in |
899 | $WATCHER. Only do so after the event loop is initialised, though. |
920 | $WATCHER, but do so only do so after the event loop is initialised. |
900 | |
921 | |
901 | our WATCHER; |
922 | our WATCHER; |
902 | |
923 | |
903 | my $guard = AnyEvent::post_detect { |
924 | my $guard = AnyEvent::post_detect { |
904 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
925 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
… | |
… | |
911 | |
932 | |
912 | $WATCHER ||= $guard; |
933 | $WATCHER ||= $guard; |
913 | |
934 | |
914 | @AnyEvent::post_detect |
935 | @AnyEvent::post_detect |
915 | If there are any code references in this array (you can "push" to it |
936 | If there are any code references in this array (you can "push" to it |
916 | before or after loading AnyEvent), then they will called directly |
937 | before or after loading AnyEvent), then they will be called directly |
917 | after the event loop has been chosen. |
938 | after the event loop has been chosen. |
918 | |
939 | |
919 | You should check $AnyEvent::MODEL before adding to this array, |
940 | You should check $AnyEvent::MODEL before adding to this array, |
920 | though: if it is defined then the event loop has already been |
941 | though: if it is defined then the event loop has already been |
921 | detected, and the array will be ignored. |
942 | detected, and the array will be ignored. |
922 | |
943 | |
923 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
944 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
924 | allows it,as it takes care of these details. |
945 | allows it, as it takes care of these details. |
925 | |
946 | |
926 | This variable is mainly useful for modules that can do something |
947 | This variable is mainly useful for modules that can do something |
927 | useful when AnyEvent is used and thus want to know when it is |
948 | useful when AnyEvent is used and thus want to know when it is |
928 | initialised, but do not need to even load it by default. This array |
949 | initialised, but do not need to even load it by default. This array |
929 | provides the means to hook into AnyEvent passively, without loading |
950 | provides the means to hook into AnyEvent passively, without loading |
930 | it. |
951 | it. |
931 | |
952 | |
|
|
953 | Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used |
|
|
954 | together, you could put this into Coro (this is the actual code used |
|
|
955 | by Coro to accomplish this): |
|
|
956 | |
|
|
957 | if (defined $AnyEvent::MODEL) { |
|
|
958 | # AnyEvent already initialised, so load Coro::AnyEvent |
|
|
959 | require Coro::AnyEvent; |
|
|
960 | } else { |
|
|
961 | # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent |
|
|
962 | # as soon as it is |
|
|
963 | push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; |
|
|
964 | } |
|
|
965 | |
|
|
966 | AnyEvent::postpone { BLOCK } |
|
|
967 | Arranges for the block to be executed as soon as possible, but not |
|
|
968 | before the call itself returns. In practise, the block will be |
|
|
969 | executed just before the event loop polls for new events, or shortly |
|
|
970 | afterwards. |
|
|
971 | |
|
|
972 | This function never returns anything (to make the "return postpone { |
|
|
973 | ... }" idiom more useful. |
|
|
974 | |
|
|
975 | To understand the usefulness of this function, consider a function |
|
|
976 | that asynchronously does something for you and returns some |
|
|
977 | transaction object or guard to let you cancel the operation. For |
|
|
978 | example, "AnyEvent::Socket::tcp_connect": |
|
|
979 | |
|
|
980 | # start a conenction attempt unless one is active |
|
|
981 | $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub { |
|
|
982 | delete $self->{connect_guard}; |
|
|
983 | ... |
|
|
984 | }; |
|
|
985 | |
|
|
986 | Imagine that this function could instantly call the callback, for |
|
|
987 | example, because it detects an obvious error such as a negative port |
|
|
988 | number. Invoking the callback before the function returns causes |
|
|
989 | problems however: the callback will be called and will try to delete |
|
|
990 | the guard object. But since the function hasn't returned yet, there |
|
|
991 | is nothing to delete. When the function eventually returns it will |
|
|
992 | assign the guard object to "$self->{connect_guard}", where it will |
|
|
993 | likely never be deleted, so the program thinks it is still trying to |
|
|
994 | connect. |
|
|
995 | |
|
|
996 | This is where "AnyEvent::postpone" should be used. Instead of |
|
|
997 | calling the callback directly on error: |
|
|
998 | |
|
|
999 | $cb->(undef), return # signal error to callback, BAD! |
|
|
1000 | if $some_error_condition; |
|
|
1001 | |
|
|
1002 | It should use "postpone": |
|
|
1003 | |
|
|
1004 | AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later |
|
|
1005 | if $some_error_condition; |
|
|
1006 | |
|
|
1007 | AnyEvent::log $level, $msg[, @args] |
|
|
1008 | Log the given $msg at the given $level. |
|
|
1009 | |
|
|
1010 | If AnyEvent::Log is not loaded then this function makes a simple |
|
|
1011 | test to see whether the message will be logged. If the test succeeds |
|
|
1012 | it will load AnyEvent::Log and call "AnyEvent::Log::log" - |
|
|
1013 | consequently, look at the AnyEvent::Log documentation for details. |
|
|
1014 | |
|
|
1015 | If the test fails it will simply return. |
|
|
1016 | |
|
|
1017 | If you want to sprinkle loads of logging calls around your code, |
|
|
1018 | consider creating a logger callback with the "AnyEvent::Log::logger" |
|
|
1019 | function, which can reduce typing, codesize and can reduce the |
|
|
1020 | logging overhead enourmously. |
|
|
1021 | |
932 | WHAT TO DO IN A MODULE |
1022 | WHAT TO DO IN A MODULE |
933 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
1023 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
934 | freely, but you should not load a specific event module or rely on it. |
1024 | freely, but you should not load a specific event module or rely on it. |
935 | |
1025 | |
936 | Be careful when you create watchers in the module body - AnyEvent will |
1026 | Be careful when you create watchers in the module body - AnyEvent will |
… | |
… | |
943 | stall the whole program, and the whole point of using events is to stay |
1033 | stall the whole program, and the whole point of using events is to stay |
944 | interactive. |
1034 | interactive. |
945 | |
1035 | |
946 | It is fine, however, to call "->recv" when the user of your module |
1036 | It is fine, however, to call "->recv" when the user of your module |
947 | requests it (i.e. if you create a http request object ad have a method |
1037 | requests it (i.e. if you create a http request object ad have a method |
948 | called "results" that returns the results, it should call "->recv" |
1038 | called "results" that returns the results, it may call "->recv" freely, |
949 | freely, as the user of your module knows what she is doing. always). |
1039 | as the user of your module knows what she is doing. Always). |
950 | |
1040 | |
951 | WHAT TO DO IN THE MAIN PROGRAM |
1041 | WHAT TO DO IN THE MAIN PROGRAM |
952 | There will always be a single main program - the only place that should |
1042 | There will always be a single main program - the only place that should |
953 | dictate which event model to use. |
1043 | dictate which event model to use. |
954 | |
1044 | |
955 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
1045 | If the program is not event-based, it need not do anything special, even |
956 | do anything special (it does not need to be event-based) and let |
1046 | when it depends on a module that uses an AnyEvent. If the program itself |
957 | AnyEvent decide which implementation to chose if some module relies on |
1047 | uses AnyEvent, but does not care which event loop is used, all it needs |
958 | it. |
1048 | to do is "use AnyEvent". In either case, AnyEvent will choose the best |
|
|
1049 | available loop implementation. |
959 | |
1050 | |
960 | If the main program relies on a specific event model - for example, in |
1051 | If the main program relies on a specific event model - for example, in |
961 | Gtk2 programs you have to rely on the Glib module - you should load the |
1052 | Gtk2 programs you have to rely on the Glib module - you should load the |
962 | event module before loading AnyEvent or any module that uses it: |
1053 | event module before loading AnyEvent or any module that uses it: |
963 | generally speaking, you should load it as early as possible. The reason |
1054 | generally speaking, you should load it as early as possible. The reason |
964 | is that modules might create watchers when they are loaded, and AnyEvent |
1055 | is that modules might create watchers when they are loaded, and AnyEvent |
965 | will decide on the event model to use as soon as it creates watchers, |
1056 | will decide on the event model to use as soon as it creates watchers, |
966 | and it might chose the wrong one unless you load the correct one |
1057 | and it might choose the wrong one unless you load the correct one |
967 | yourself. |
1058 | yourself. |
968 | |
1059 | |
969 | You can chose to use a pure-perl implementation by loading the |
1060 | You can chose to use a pure-perl implementation by loading the |
970 | "AnyEvent::Impl::Perl" module, which gives you similar behaviour |
1061 | "AnyEvent::Loop" module, which gives you similar behaviour everywhere, |
971 | everywhere, but letting AnyEvent chose the model is generally better. |
1062 | but letting AnyEvent chose the model is generally better. |
972 | |
1063 | |
973 | MAINLOOP EMULATION |
1064 | MAINLOOP EMULATION |
974 | Sometimes (often for short test scripts, or even standalone programs who |
1065 | Sometimes (often for short test scripts, or even standalone programs who |
975 | only want to use AnyEvent), you do not want to run a specific event |
1066 | only want to use AnyEvent), you do not want to run a specific event |
976 | loop. |
1067 | loop. |
… | |
… | |
988 | |
1079 | |
989 | OTHER MODULES |
1080 | OTHER MODULES |
990 | The following is a non-exhaustive list of additional modules that use |
1081 | The following is a non-exhaustive list of additional modules that use |
991 | AnyEvent as a client and can therefore be mixed easily with other |
1082 | AnyEvent as a client and can therefore be mixed easily with other |
992 | AnyEvent modules and other event loops in the same program. Some of the |
1083 | AnyEvent modules and other event loops in the same program. Some of the |
993 | modules come with AnyEvent, most are available via CPAN. |
1084 | modules come as part of AnyEvent, the others are available via CPAN (see |
|
|
1085 | <http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for a longer |
|
|
1086 | non-exhaustive list), and the list is heavily biased towards modules of |
|
|
1087 | the AnyEvent author himself :) |
994 | |
1088 | |
995 | AnyEvent::Util |
1089 | AnyEvent::Util |
996 | Contains various utility functions that replace often-used but |
1090 | Contains various utility functions that replace often-used blocking |
997 | blocking functions such as "inet_aton" by event-/callback-based |
1091 | functions such as "inet_aton" with event/callback-based versions. |
998 | versions. |
|
|
999 | |
1092 | |
1000 | AnyEvent::Socket |
1093 | AnyEvent::Socket |
1001 | Provides various utility functions for (internet protocol) sockets, |
1094 | Provides various utility functions for (internet protocol) sockets, |
1002 | addresses and name resolution. Also functions to create non-blocking |
1095 | addresses and name resolution. Also functions to create non-blocking |
1003 | tcp connections or tcp servers, with IPv6 and SRV record support and |
1096 | tcp connections or tcp servers, with IPv6 and SRV record support and |
1004 | more. |
1097 | more. |
1005 | |
1098 | |
1006 | AnyEvent::Handle |
1099 | AnyEvent::Handle |
1007 | Provide read and write buffers, manages watchers for reads and |
1100 | Provide read and write buffers, manages watchers for reads and |
1008 | writes, supports raw and formatted I/O, I/O queued and fully |
1101 | writes, supports raw and formatted I/O, I/O queued and fully |
1009 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
1102 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS). |
1010 | |
1103 | |
1011 | AnyEvent::DNS |
1104 | AnyEvent::DNS |
1012 | Provides rich asynchronous DNS resolver capabilities. |
1105 | Provides rich asynchronous DNS resolver capabilities. |
1013 | |
1106 | |
|
|
1107 | AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, |
|
|
1108 | AnyEvent::IGS, AnyEvent::FCP |
|
|
1109 | Implement event-based interfaces to the protocols of the same name |
|
|
1110 | (for the curious, IGS is the International Go Server and FCP is the |
|
|
1111 | Freenet Client Protocol). |
|
|
1112 | |
1014 | AnyEvent::HTTP |
1113 | AnyEvent::AIO |
1015 | A simple-to-use HTTP library that is capable of making a lot of |
1114 | Truly asynchronous (as opposed to non-blocking) I/O, should be in |
1016 | concurrent HTTP requests. |
1115 | the toolbox of every event programmer. AnyEvent::AIO transparently |
|
|
1116 | fuses IO::AIO and AnyEvent together, giving AnyEvent access to |
|
|
1117 | event-based file I/O, and much more. |
|
|
1118 | |
|
|
1119 | AnyEvent::Filesys::Notify |
|
|
1120 | AnyEvent is good for non-blocking stuff, but it can't detect file or |
|
|
1121 | path changes (e.g. "watch this directory for new files", "watch this |
|
|
1122 | file for changes"). The AnyEvent::Filesys::Notify module promises to |
|
|
1123 | do just that in a portbale fashion, supporting inotify on GNU/Linux |
|
|
1124 | and some weird, without doubt broken, stuff on OS X to monitor |
|
|
1125 | files. It can fall back to blocking scans at regular intervals |
|
|
1126 | transparently on other platforms, so it's about as portable as it |
|
|
1127 | gets. |
|
|
1128 | |
|
|
1129 | (I haven't used it myself, but I haven't heard anybody complaining |
|
|
1130 | about it yet). |
|
|
1131 | |
|
|
1132 | AnyEvent::DBI |
|
|
1133 | Executes DBI requests asynchronously in a proxy process for you, |
|
|
1134 | notifying you in an event-based way when the operation is finished. |
1017 | |
1135 | |
1018 | AnyEvent::HTTPD |
1136 | AnyEvent::HTTPD |
1019 | Provides a simple web application server framework. |
1137 | A simple embedded webserver. |
1020 | |
1138 | |
1021 | AnyEvent::FastPing |
1139 | AnyEvent::FastPing |
1022 | The fastest ping in the west. |
1140 | The fastest ping in the west. |
1023 | |
1141 | |
1024 | AnyEvent::DBI |
|
|
1025 | Executes DBI requests asynchronously in a proxy process. |
|
|
1026 | |
|
|
1027 | AnyEvent::AIO |
|
|
1028 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
1029 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
1030 | together. |
|
|
1031 | |
|
|
1032 | AnyEvent::BDB |
|
|
1033 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
1034 | fuses BDB and AnyEvent together. |
|
|
1035 | |
|
|
1036 | AnyEvent::GPSD |
|
|
1037 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
1038 | information. |
|
|
1039 | |
|
|
1040 | AnyEvent::IRC |
|
|
1041 | AnyEvent based IRC client module family (replacing the older |
|
|
1042 | Net::IRC3). |
|
|
1043 | |
|
|
1044 | AnyEvent::XMPP |
|
|
1045 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
1046 | older Net::XMPP2>. |
|
|
1047 | |
|
|
1048 | AnyEvent::IGS |
|
|
1049 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
1050 | App::IGS). |
|
|
1051 | |
|
|
1052 | Net::FCP |
|
|
1053 | AnyEvent-based implementation of the Freenet Client Protocol, |
|
|
1054 | birthplace of AnyEvent. |
|
|
1055 | |
|
|
1056 | Event::ExecFlow |
|
|
1057 | High level API for event-based execution flow control. |
|
|
1058 | |
|
|
1059 | Coro |
1142 | Coro |
1060 | Has special support for AnyEvent via Coro::AnyEvent. |
1143 | Has special support for AnyEvent via Coro::AnyEvent, which allows |
|
|
1144 | you to simply invert the flow control - don't call us, we will call |
|
|
1145 | you: |
|
|
1146 | |
|
|
1147 | async { |
|
|
1148 | Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it |
|
|
1149 | print "5 seconds later!\n"; |
|
|
1150 | |
|
|
1151 | Coro::AnyEvent::readable *STDIN; # uses an I/O watcher |
|
|
1152 | my $line = <STDIN>; # works for ttys |
|
|
1153 | |
|
|
1154 | AnyEvent::HTTP::http_get "url", Coro::rouse_cb; |
|
|
1155 | my ($body, $hdr) = Coro::rouse_wait; |
|
|
1156 | }; |
1061 | |
1157 | |
1062 | SIMPLIFIED AE API |
1158 | SIMPLIFIED AE API |
1063 | Starting with version 5.0, AnyEvent officially supports a second, much |
1159 | Starting with version 5.0, AnyEvent officially supports a second, much |
1064 | simpler, API that is designed to reduce the calling, typing and memory |
1160 | simpler, API that is designed to reduce the calling, typing and memory |
1065 | overhead. |
1161 | overhead by using function call syntax and a fixed number of parameters. |
1066 | |
1162 | |
1067 | See the AE manpage for details. |
1163 | See the AE manpage for details. |
1068 | |
1164 | |
1069 | ERROR AND EXCEPTION HANDLING |
1165 | ERROR AND EXCEPTION HANDLING |
1070 | In general, AnyEvent does not do any error handling - it relies on the |
1166 | In general, AnyEvent does not do any error handling - it relies on the |
… | |
… | |
1081 | The pure perl event loop simply re-throws the exception (usually within |
1177 | The pure perl event loop simply re-throws the exception (usually within |
1082 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
1178 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
1083 | Glib uses "install_exception_handler" and so on. |
1179 | Glib uses "install_exception_handler" and so on. |
1084 | |
1180 | |
1085 | ENVIRONMENT VARIABLES |
1181 | ENVIRONMENT VARIABLES |
1086 | The following environment variables are used by this module or its |
1182 | AnyEvent supports a number of environment variables that tune the |
1087 | submodules. |
1183 | runtime behaviour. They are usually evaluated when AnyEvent is loaded, |
|
|
1184 | initialised, or a submodule that uses them is loaded. Many of them also |
|
|
1185 | cause AnyEvent to load additional modules - for example, |
|
|
1186 | "PERL_ANYEVENT_DEBUG_WRAP" causes the AnyEvent::Debug module to be |
|
|
1187 | loaded. |
1088 | |
1188 | |
1089 | Note that AnyEvent will remove *all* environment variables starting with |
1189 | All the environment variables documented here start with |
1090 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
1190 | "PERL_ANYEVENT_", which is what AnyEvent considers its own namespace. |
1091 | enabled. |
1191 | Other modules are encouraged (but by no means required) to use |
|
|
1192 | "PERL_ANYEVENT_SUBMODULE" if they have registered the |
|
|
1193 | AnyEvent::Submodule namespace on CPAN, for any submodule. For example, |
|
|
1194 | AnyEvent::HTTP could be expected to use "PERL_ANYEVENT_HTTP_PROXY" (it |
|
|
1195 | should not access env variables starting with "AE_", see below). |
|
|
1196 | |
|
|
1197 | All variables can also be set via the "AE_" prefix, that is, instead of |
|
|
1198 | setting "PERL_ANYEVENT_VERBOSE" you can also set "AE_VERBOSE". In case |
|
|
1199 | there is a clash btween anyevent and another program that uses |
|
|
1200 | "AE_something" you can set the corresponding "PERL_ANYEVENT_something" |
|
|
1201 | variable to the empty string, as those variables take precedence. |
|
|
1202 | |
|
|
1203 | When AnyEvent is first loaded, it copies all "AE_xxx" env variables to |
|
|
1204 | their "PERL_ANYEVENT_xxx" counterpart unless that variable already |
|
|
1205 | exists. If taint mode is on, then AnyEvent will remove *all* environment |
|
|
1206 | variables starting with "PERL_ANYEVENT_" from %ENV (or replace them with |
|
|
1207 | "undef" or the empty string, if the corresaponding "AE_" variable is |
|
|
1208 | set). |
|
|
1209 | |
|
|
1210 | The exact algorithm is currently: |
|
|
1211 | |
|
|
1212 | 1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV |
|
|
1213 | 2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists |
|
|
1214 | 3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef. |
|
|
1215 | |
|
|
1216 | This ensures that child processes will not see the "AE_" variables. |
|
|
1217 | |
|
|
1218 | The following environment variables are currently known to AnyEvent: |
1092 | |
1219 | |
1093 | "PERL_ANYEVENT_VERBOSE" |
1220 | "PERL_ANYEVENT_VERBOSE" |
1094 | By default, AnyEvent will be completely silent except in fatal |
1221 | By default, AnyEvent will be completely silent except in fatal |
1095 | conditions. You can set this environment variable to make AnyEvent |
1222 | conditions. You can set this environment variable to make AnyEvent |
1096 | more talkative. |
1223 | more talkative. If you want to do more than just set the global |
|
|
1224 | logging level you should have a look at "PERL_ANYEVENT_LOG", which |
|
|
1225 | allows much more complex specifications. |
1097 | |
1226 | |
1098 | When set to 1 or higher, causes AnyEvent to warn about unexpected |
1227 | When set to 5 or higher (warn), causes AnyEvent to warn about |
1099 | conditions, such as not being able to load the event model specified |
1228 | unexpected conditions, such as not being able to load the event |
1100 | by "PERL_ANYEVENT_MODEL". |
1229 | model specified by "PERL_ANYEVENT_MODEL", or a guard callback |
|
|
1230 | throwing an exception - this is the minimum recommended level. |
1101 | |
1231 | |
1102 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
1232 | When set to 7 or higher (info), cause AnyEvent to report which event |
1103 | event model it chooses. |
1233 | model it chooses. |
1104 | |
1234 | |
1105 | When set to 8 or higher, then AnyEvent will report extra information |
1235 | When set to 8 or higher (debug), then AnyEvent will report extra |
1106 | on which optional modules it loads and how it implements certain |
1236 | information on which optional modules it loads and how it implements |
1107 | features. |
1237 | certain features. |
|
|
1238 | |
|
|
1239 | "PERL_ANYEVENT_LOG" |
|
|
1240 | Accepts rather complex logging specifications. For example, you |
|
|
1241 | could log all "debug" messages of some module to stderr, warnings |
|
|
1242 | and above to stderr, and errors and above to syslog, with: |
|
|
1243 | |
|
|
1244 | PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog |
|
|
1245 | |
|
|
1246 | For the rather extensive details, see AnyEvent::Log. |
|
|
1247 | |
|
|
1248 | This variable is evaluated when AnyEvent (or AnyEvent::Log) is |
|
|
1249 | loaded, so will take effect even before AnyEvent has initialised |
|
|
1250 | itself. |
|
|
1251 | |
|
|
1252 | Note that specifying this environment variable causes the |
|
|
1253 | AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE" |
|
|
1254 | does not, so only using the latter saves a few hundred kB of memory |
|
|
1255 | until the first message is being logged. |
1108 | |
1256 | |
1109 | "PERL_ANYEVENT_STRICT" |
1257 | "PERL_ANYEVENT_STRICT" |
1110 | AnyEvent does not do much argument checking by default, as thorough |
1258 | AnyEvent does not do much argument checking by default, as thorough |
1111 | argument checking is very costly. Setting this variable to a true |
1259 | argument checking is very costly. Setting this variable to a true |
1112 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1260 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1113 | thoroughly check the arguments passed to most method calls. If it |
1261 | thoroughly check the arguments passed to most method calls. If it |
1114 | finds any problems, it will croak. |
1262 | finds any problems, it will croak. |
1115 | |
1263 | |
1116 | In other words, enables "strict" mode. |
1264 | In other words, enables "strict" mode. |
1117 | |
1265 | |
1118 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
1266 | Unlike "use strict" (or its modern cousin, "use common::sense", it |
1119 | is definitely recommended to keep it off in production. Keeping |
1267 | is definitely recommended to keep it off in production. Keeping |
1120 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1268 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1121 | programs can be very useful, however. |
1269 | programs can be very useful, however. |
1122 | |
1270 | |
|
|
1271 | "PERL_ANYEVENT_DEBUG_SHELL" |
|
|
1272 | If this env variable is set, then its contents will be interpreted |
|
|
1273 | by "AnyEvent::Socket::parse_hostport" (after replacing every |
|
|
1274 | occurance of $$ by the process pid) and an "AnyEvent::Debug::shell" |
|
|
1275 | is bound on that port. The shell object is saved in |
|
|
1276 | $AnyEvent::Debug::SHELL. |
|
|
1277 | |
|
|
1278 | This happens when the first watcher is created. |
|
|
1279 | |
|
|
1280 | For example, to bind a debug shell on a unix domain socket in |
|
|
1281 | /tmp/debug<pid>.sock, you could use this: |
|
|
1282 | |
|
|
1283 | PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog |
|
|
1284 | |
|
|
1285 | Note that creating sockets in /tmp is very unsafe on multiuser |
|
|
1286 | systems. |
|
|
1287 | |
|
|
1288 | "PERL_ANYEVENT_DEBUG_WRAP" |
|
|
1289 | Can be set to 0, 1 or 2 and enables wrapping of all watchers for |
|
|
1290 | debugging purposes. See "AnyEvent::Debug::wrap" for details. |
|
|
1291 | |
1123 | "PERL_ANYEVENT_MODEL" |
1292 | "PERL_ANYEVENT_MODEL" |
1124 | This can be used to specify the event model to be used by AnyEvent, |
1293 | This can be used to specify the event model to be used by AnyEvent, |
1125 | before auto detection and -probing kicks in. It must be a string |
1294 | before auto detection and -probing kicks in. |
1126 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1295 | |
1127 | gets prepended and the resulting module name is loaded and if the |
1296 | It normally is a string consisting entirely of ASCII letters (e.g. |
1128 | load was successful, used as event model. If it fails to load |
1297 | "EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and |
|
|
1298 | the resulting module name is loaded and - if the load was successful |
|
|
1299 | - used as event model backend. If it fails to load then AnyEvent |
1129 | AnyEvent will proceed with auto detection and -probing. |
1300 | will proceed with auto detection and -probing. |
1130 | |
1301 | |
1131 | This functionality might change in future versions. |
1302 | If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::") |
|
|
1303 | then nothing gets prepended and the module name is used as-is (hint: |
|
|
1304 | "::" at the end of a string designates a module name and quotes it |
|
|
1305 | appropriately). |
1132 | |
1306 | |
1133 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
1307 | For example, to force the pure perl model (AnyEvent::Loop::Perl) you |
1134 | could start your program like this: |
1308 | could start your program like this: |
1135 | |
1309 | |
1136 | PERL_ANYEVENT_MODEL=Perl perl ... |
1310 | PERL_ANYEVENT_MODEL=Perl perl ... |
1137 | |
1311 | |
1138 | "PERL_ANYEVENT_PROTOCOLS" |
1312 | "PERL_ANYEVENT_PROTOCOLS" |
… | |
… | |
1155 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1329 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1156 | resolve or contact IPv6 addresses. |
1330 | resolve or contact IPv6 addresses. |
1157 | "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but |
1331 | "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but |
1158 | prefer IPv6 over IPv4. |
1332 | prefer IPv6 over IPv4. |
1159 | |
1333 | |
|
|
1334 | "PERL_ANYEVENT_HOSTS" |
|
|
1335 | This variable, if specified, overrides the /etc/hosts file used by |
|
|
1336 | AnyEvent::Socket"::resolve_sockaddr", i.e. hosts aliases will be |
|
|
1337 | read from that file instead. |
|
|
1338 | |
1160 | "PERL_ANYEVENT_EDNS0" |
1339 | "PERL_ANYEVENT_EDNS0" |
1161 | Used by AnyEvent::DNS to decide whether to use the EDNS0 extension |
1340 | Used by AnyEvent::DNS to decide whether to use the EDNS0 extension |
1162 | for DNS. This extension is generally useful to reduce DNS traffic, |
1341 | for DNS. This extension is generally useful to reduce DNS traffic, |
1163 | but some (broken) firewalls drop such DNS packets, which is why it |
1342 | especially when DNSSEC is involved, but some (broken) firewalls drop |
1164 | is off by default. |
1343 | such DNS packets, which is why it is off by default. |
1165 | |
1344 | |
1166 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
1345 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
1167 | EDNS0 in its DNS requests. |
1346 | EDNS0 in its DNS requests. |
1168 | |
1347 | |
1169 | "PERL_ANYEVENT_MAX_FORKS" |
1348 | "PERL_ANYEVENT_MAX_FORKS" |
… | |
… | |
1174 | The default value for the "max_outstanding" parameter for the |
1353 | The default value for the "max_outstanding" parameter for the |
1175 | default DNS resolver - this is the maximum number of parallel DNS |
1354 | default DNS resolver - this is the maximum number of parallel DNS |
1176 | requests that are sent to the DNS server. |
1355 | requests that are sent to the DNS server. |
1177 | |
1356 | |
1178 | "PERL_ANYEVENT_RESOLV_CONF" |
1357 | "PERL_ANYEVENT_RESOLV_CONF" |
1179 | The file to use instead of /etc/resolv.conf (or OS-specific |
1358 | The absolute path to a resolv.conf-style file to use instead of |
1180 | configuration) in the default resolver. When set to the empty |
1359 | /etc/resolv.conf (or the OS-specific configuration) in the default |
1181 | string, no default config will be used. |
1360 | resolver, or the empty string to select the default configuration. |
1182 | |
1361 | |
1183 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
1362 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
1184 | When neither "ca_file" nor "ca_path" was specified during |
1363 | When neither "ca_file" nor "ca_path" was specified during |
1185 | AnyEvent::TLS context creation, and either of these environment |
1364 | AnyEvent::TLS context creation, and either of these environment |
1186 | variables exist, they will be used to specify CA certificate |
1365 | variables are nonempty, they will be used to specify CA certificate |
1187 | locations instead of a system-dependent default. |
1366 | locations instead of a system-dependent default. |
1188 | |
1367 | |
1189 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
1368 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
1190 | When these are set to 1, then the respective modules are not loaded. |
1369 | When these are set to 1, then the respective modules are not loaded. |
1191 | Mostly good for testing AnyEvent itself. |
1370 | Mostly good for testing AnyEvent itself. |
… | |
… | |
1335 | |
1514 | |
1336 | The actual code goes further and collects all errors ("die"s, |
1515 | The actual code goes further and collects all errors ("die"s, |
1337 | exceptions) that occurred during request processing. The "result" method |
1516 | exceptions) that occurred during request processing. The "result" method |
1338 | detects whether an exception as thrown (it is stored inside the $txn |
1517 | detects whether an exception as thrown (it is stored inside the $txn |
1339 | object) and just throws the exception, which means connection errors and |
1518 | object) and just throws the exception, which means connection errors and |
1340 | other problems get reported tot he code that tries to use the result, |
1519 | other problems get reported to the code that tries to use the result, |
1341 | not in a random callback. |
1520 | not in a random callback. |
1342 | |
1521 | |
1343 | All of this enables the following usage styles: |
1522 | All of this enables the following usage styles: |
1344 | |
1523 | |
1345 | 1. Blocking: |
1524 | 1. Blocking: |
… | |
… | |
1511 | when used without AnyEvent), but most event loops have acceptable |
1690 | when used without AnyEvent), but most event loops have acceptable |
1512 | performance with or without AnyEvent. |
1691 | performance with or without AnyEvent. |
1513 | |
1692 | |
1514 | * The overhead AnyEvent adds is usually much smaller than the overhead |
1693 | * The overhead AnyEvent adds is usually much smaller than the overhead |
1515 | of the actual event loop, only with extremely fast event loops such |
1694 | of the actual event loop, only with extremely fast event loops such |
1516 | as EV adds AnyEvent significant overhead. |
1695 | as EV does AnyEvent add significant overhead. |
1517 | |
1696 | |
1518 | * You should avoid POE like the plague if you want performance or |
1697 | * You should avoid POE like the plague if you want performance or |
1519 | reasonable memory usage. |
1698 | reasonable memory usage. |
1520 | |
1699 | |
1521 | BENCHMARKING THE LARGE SERVER CASE |
1700 | BENCHMARKING THE LARGE SERVER CASE |
… | |
… | |
1719 | |
1898 | |
1720 | Feel free to install your own handler, or reset it to defaults. |
1899 | Feel free to install your own handler, or reset it to defaults. |
1721 | |
1900 | |
1722 | RECOMMENDED/OPTIONAL MODULES |
1901 | RECOMMENDED/OPTIONAL MODULES |
1723 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
1902 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
1724 | it's built-in modules) are required to use it. |
1903 | its built-in modules) are required to use it. |
1725 | |
1904 | |
1726 | That does not mean that AnyEvent won't take advantage of some additional |
1905 | That does not mean that AnyEvent won't take advantage of some additional |
1727 | modules if they are installed. |
1906 | modules if they are installed. |
1728 | |
1907 | |
1729 | This section explains which additional modules will be used, and how |
1908 | This section explains which additional modules will be used, and how |
… | |
… | |
1758 | clock is available, can take avdantage of advanced kernel interfaces |
1937 | clock is available, can take avdantage of advanced kernel interfaces |
1759 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
1938 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
1760 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
1939 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
1761 | Glib::EV). |
1940 | Glib::EV). |
1762 | |
1941 | |
|
|
1942 | If you only use backends that rely on another event loop (e.g. |
|
|
1943 | "Tk"), then this module will do nothing for you. |
|
|
1944 | |
1763 | Guard |
1945 | Guard |
1764 | The guard module, when used, will be used to implement |
1946 | The guard module, when used, will be used to implement |
1765 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
1947 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
1766 | uses a lot less memory), but otherwise doesn't affect guard |
1948 | uses a lot less memory), but otherwise doesn't affect guard |
1767 | operation much. It is purely used for performance. |
1949 | operation much. It is purely used for performance. |
1768 | |
1950 | |
1769 | JSON and JSON::XS |
1951 | JSON and JSON::XS |
1770 | One of these modules is required when you want to read or write JSON |
1952 | One of these modules is required when you want to read or write JSON |
1771 | data via AnyEvent::Handle. It is also written in pure-perl, but can |
1953 | data via AnyEvent::Handle. JSON is also written in pure-perl, but |
1772 | take advantage of the ultra-high-speed JSON::XS module when it is |
1954 | can take advantage of the ultra-high-speed JSON::XS module when it |
1773 | installed. |
1955 | is installed. |
1774 | |
|
|
1775 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1776 | installed. |
|
|
1777 | |
1956 | |
1778 | Net::SSLeay |
1957 | Net::SSLeay |
1779 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
1958 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
1780 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
1959 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
1781 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
1960 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
1782 | |
1961 | |
1783 | Time::HiRes |
1962 | Time::HiRes |
1784 | This module is part of perl since release 5.008. It will be used |
1963 | This module is part of perl since release 5.008. It will be used |
1785 | when the chosen event library does not come with a timing source on |
1964 | when the chosen event library does not come with a timing source of |
1786 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
1965 | its own. The pure-perl event loop (AnyEvent::Loop) will additionally |
1787 | additionally use it to try to use a monotonic clock for timing |
1966 | load it to try to use a monotonic clock for timing stability. |
1788 | stability. |
|
|
1789 | |
1967 | |
1790 | FORK |
1968 | FORK |
1791 | Most event libraries are not fork-safe. The ones who are usually are |
1969 | Most event libraries are not fork-safe. The ones who are usually are |
1792 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1970 | because they rely on inefficient but fork-safe "select" or "poll" calls |
1793 | Only EV is fully fork-aware. |
1971 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
|
|
1972 | epoll are usually badly thought-out hacks that are incompatible with |
|
|
1973 | fork in one way or another. Only EV is fully fork-aware and ensures that |
|
|
1974 | you continue event-processing in both parent and child (or both, if you |
|
|
1975 | know what you are doing). |
1794 | |
1976 | |
1795 | This means that, in general, you cannot fork and do event processing in |
1977 | This means that, in general, you cannot fork and do event processing in |
1796 | the child if a watcher was created before the fork (which in turn |
1978 | the child if the event library was initialised before the fork (which |
1797 | initialises the event library). |
1979 | usually happens when the first AnyEvent watcher is created, or the |
|
|
1980 | library is loaded). |
1798 | |
1981 | |
1799 | If you have to fork, you must either do so *before* creating your first |
1982 | If you have to fork, you must either do so *before* creating your first |
1800 | watcher OR you must not use AnyEvent at all in the child OR you must do |
1983 | watcher OR you must not use AnyEvent at all in the child OR you must do |
1801 | something completely out of the scope of AnyEvent. |
1984 | something completely out of the scope of AnyEvent. |
1802 | |
1985 | |
1803 | The problem of doing event processing in the parent *and* the child is |
1986 | The problem of doing event processing in the parent *and* the child is |
1804 | much more complicated: even for backends that *are* fork-aware or |
1987 | much more complicated: even for backends that *are* fork-aware or |
1805 | fork-safe, their behaviour is not usually what you want: fork clones all |
1988 | fork-safe, their behaviour is not usually what you want: fork clones all |
1806 | watchers, that means all timers, I/O watchers etc. are active in both |
1989 | watchers, that means all timers, I/O watchers etc. are active in both |
1807 | parent and child, which is almost never what you want. |
1990 | parent and child, which is almost never what you want. USing "exec" to |
|
|
1991 | start worker children from some kind of manage rprocess is usually |
|
|
1992 | preferred, because it is much easier and cleaner, at the expense of |
|
|
1993 | having to have another binary. |
1808 | |
1994 | |
1809 | SECURITY CONSIDERATIONS |
1995 | SECURITY CONSIDERATIONS |
1810 | AnyEvent can be forced to load any event model via |
1996 | AnyEvent can be forced to load any event model via |
1811 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1997 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1812 | to execute arbitrary code or directly gain access, it can easily be used |
1998 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1836 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
2022 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1837 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
2023 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1838 | not as pronounced). |
2024 | not as pronounced). |
1839 | |
2025 | |
1840 | SEE ALSO |
2026 | SEE ALSO |
1841 | Utility functions: AnyEvent::Util. |
2027 | Tutorial/Introduction: AnyEvent::Intro. |
1842 | |
2028 | |
1843 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
2029 | FAQ: AnyEvent::FAQ. |
1844 | Event::Lib, Qt, POE. |
2030 | |
|
|
2031 | Utility functions: AnyEvent::Util (misc. grab-bag), AnyEvent::Log |
|
|
2032 | (simply logging). |
|
|
2033 | |
|
|
2034 | Development/Debugging: AnyEvent::Strict (stricter checking), |
|
|
2035 | AnyEvent::Debug (interactive shell, watcher tracing). |
|
|
2036 | |
|
|
2037 | Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event, |
|
|
2038 | Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK. |
1845 | |
2039 | |
1846 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
2040 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1847 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
2041 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1848 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
2042 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
1849 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. |
2043 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi, AnyEvent::Impl::FLTK. |
1850 | |
2044 | |
1851 | Non-blocking file handles, sockets, TCP clients and servers: |
2045 | Non-blocking handles, pipes, stream sockets, TCP clients and servers: |
1852 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
2046 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1853 | |
2047 | |
1854 | Asynchronous DNS: AnyEvent::DNS. |
2048 | Asynchronous DNS: AnyEvent::DNS. |
1855 | |
2049 | |
1856 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
2050 | Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. |
1857 | |
2051 | |
1858 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
2052 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, |
1859 | AnyEvent::HTTP. |
2053 | AnyEvent::HTTP. |
1860 | |
2054 | |
1861 | AUTHOR |
2055 | AUTHOR |
1862 | Marc Lehmann <schmorp@schmorp.de> |
2056 | Marc Lehmann <schmorp@schmorp.de> |
1863 | http://home.schmorp.de/ |
2057 | http://home.schmorp.de/ |