1 | NAME |
1 | NAME |
2 | AnyEvent - events independent of event loop implementation |
2 | AnyEvent - the DBI of event loop programming |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, |
5 | event loops. |
5 | Qt and POE are various supported event loops/environments. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
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10 | # if you prefer function calls, look at the AE manpage for |
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11 | # an alternative API. |
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12 | |
10 | # file descriptor readable |
13 | # file handle or descriptor readable |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
14 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
12 | |
15 | |
13 | # one-shot or repeating timers |
16 | # one-shot or repeating timers |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
17 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
18 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...); |
16 | |
19 | |
17 | print AnyEvent->now; # prints current event loop time |
20 | print AnyEvent->now; # prints current event loop time |
18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
21 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
19 | |
22 | |
20 | # POSIX signal |
23 | # POSIX signal |
… | |
… | |
39 | This manpage is mainly a reference manual. If you are interested in a |
42 | This manpage is mainly a reference manual. If you are interested in a |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
43 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
41 | manpage. |
44 | manpage. |
42 | |
45 | |
43 | SUPPORT |
46 | SUPPORT |
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47 | An FAQ document is available as AnyEvent::FAQ. |
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48 | |
44 | There is a mailinglist for discussing all things AnyEvent, and an IRC |
49 | There also is a mailinglist for discussing all things AnyEvent, and an |
45 | channel, too. |
50 | IRC channel, too. |
46 | |
51 | |
47 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
52 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
48 | Respository, 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) |
51 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
56 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
52 | nowadays. So what is different about AnyEvent? |
57 | nowadays. So what is different about AnyEvent? |
53 | |
58 | |
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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 + IO::Async? No go. Tk + Event? No go. Again: if your |
81 | module uses one of those, every user of your module has to use it, too. |
86 | module uses one of those, every user of your module has to use it, too. |
82 | But if your module uses AnyEvent, it works transparently with all event |
87 | But if your module uses AnyEvent, it works transparently with all event |
83 | models it supports (including stuff like IO::Async, as long as those use |
88 | models it supports (including stuff like IO::Async, as long as those use |
84 | one of the supported event loops. It is trivial to add new event loops |
89 | one of 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 |
… | |
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100 | Now, if you *do want* lots of policy (this can arguably be somewhat |
105 | Now, if you *do want* lots of policy (this can arguably be somewhat |
101 | useful) and you want to force your users to use the one and only event |
106 | useful) and you want to force your users to use the one and only event |
102 | model, you should *not* use this module. |
107 | model, you should *not* use this module. |
103 | |
108 | |
104 | DESCRIPTION |
109 | DESCRIPTION |
105 | AnyEvent provides an identical interface to multiple event loops. This |
110 | AnyEvent provides a uniform interface to various event loops. This |
106 | allows module authors to utilise an event loop without forcing module |
111 | allows module authors to use event loop functionality without forcing |
107 | users to use the same event loop (as only a single event loop can |
112 | module users to use a specific event loop implementation (since more |
108 | coexist peacefully at any one time). |
113 | than one event loop cannot coexist peacefully). |
109 | |
114 | |
110 | The interface itself is vaguely similar, but not identical to the Event |
115 | The interface itself is vaguely similar, but not identical to the Event |
111 | module. |
116 | module. |
112 | |
117 | |
113 | During the first call of any watcher-creation method, the module tries |
118 | During the first call of any watcher-creation method, the module tries |
114 | to detect the currently loaded event loop by probing whether one of the |
119 | to detect the currently loaded event loop by probing whether one of the |
115 | following modules is already loaded: EV, Event, Glib, |
120 | following modules is already loaded: EV, AnyEvent::Impl::Perl, Event, |
116 | AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found is |
121 | Glib, Tk, Event::Lib, Qt, POE. The first one found is used. If none are |
117 | used. If none are found, the module tries to load these modules |
122 | detected, the module tries to load the first four modules in the order |
118 | (excluding Tk, Event::Lib, Qt and POE as the pure perl adaptor should |
123 | given; but note that if EV is not available, the pure-perl |
119 | always succeed) in the order given. The first one that can be |
124 | AnyEvent::Impl::Perl should always work, so the other two are not |
120 | successfully loaded will be used. If, after this, still none could be |
125 | normally tried. |
121 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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122 | very efficient, but should work everywhere. |
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123 | |
126 | |
124 | Because AnyEvent first checks for modules that are already loaded, |
127 | Because AnyEvent first checks for modules that are already loaded, |
125 | loading an event model explicitly before first using AnyEvent will |
128 | loading an event model explicitly before first using AnyEvent will |
126 | likely make that model the default. For example: |
129 | likely make that model the default. For example: |
127 | |
130 | |
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129 | use AnyEvent; |
132 | use AnyEvent; |
130 | |
133 | |
131 | # .. AnyEvent will likely default to Tk |
134 | # .. AnyEvent will likely default to Tk |
132 | |
135 | |
133 | The *likely* means that, if any module loads another event model and |
136 | The *likely* means that, if any module loads another event model and |
134 | starts using it, all bets are off. Maybe you should tell their authors |
137 | starts using it, all bets are off - this case should be very rare |
135 | to use AnyEvent so their modules work together with others seamlessly... |
138 | though, as very few modules hardcode event loops without announcing this |
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139 | very loudly. |
136 | |
140 | |
137 | The pure-perl implementation of AnyEvent is called |
141 | The pure-perl implementation of AnyEvent is called |
138 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
142 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
139 | explicitly and enjoy the high availability of that event loop :) |
143 | explicitly and enjoy the high availability of that event loop :) |
140 | |
144 | |
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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 | }); |
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173 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
177 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
174 | my variables are only visible after the statement in which they are |
178 | my variables are only visible after the statement in which they are |
175 | declared. |
179 | declared. |
176 | |
180 | |
177 | I/O WATCHERS |
181 | I/O WATCHERS |
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182 | $w = AnyEvent->io ( |
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183 | fh => <filehandle_or_fileno>, |
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184 | poll => <"r" or "w">, |
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185 | cb => <callback>, |
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186 | ); |
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187 | |
178 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
188 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
179 | the following mandatory key-value pairs as arguments: |
189 | the following mandatory key-value pairs as arguments: |
180 | |
190 | |
181 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
191 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
182 | events (AnyEvent might or might not keep a reference to this file |
192 | events (AnyEvent might or might not keep a reference to this file |
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196 | |
206 | |
197 | 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 |
198 | 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 |
199 | the underlying file descriptor. |
209 | the underlying file descriptor. |
200 | |
210 | |
201 | Some event loops issue spurious readyness notifications, so you should |
211 | Some event loops issue spurious readiness notifications, so you should |
202 | 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 |
203 | handles. |
213 | handles. |
204 | |
214 | |
205 | 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 |
206 | watcher. |
216 | watcher. |
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210 | warn "read: $input\n"; |
220 | warn "read: $input\n"; |
211 | undef $w; |
221 | undef $w; |
212 | }); |
222 | }); |
213 | |
223 | |
214 | TIME WATCHERS |
224 | TIME WATCHERS |
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225 | $w = AnyEvent->timer (after => <seconds>, cb => <callback>); |
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226 | |
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227 | $w = AnyEvent->timer ( |
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228 | after => <fractional_seconds>, |
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229 | interval => <fractional_seconds>, |
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230 | cb => <callback>, |
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231 | ); |
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232 | |
215 | You can create a time watcher by calling the "AnyEvent->timer" method |
233 | You can create a time watcher by calling the "AnyEvent->timer" method |
216 | with the following mandatory arguments: |
234 | with the following mandatory arguments: |
217 | |
235 | |
218 | "after" specifies after how many seconds (fractional values are |
236 | "after" specifies after how many seconds (fractional values are |
219 | supported) the callback should be invoked. "cb" is the callback to |
237 | supported) the callback should be invoked. "cb" is the callback to |
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221 | |
239 | |
222 | Although the callback might get passed parameters, their value and |
240 | Although the callback might get passed parameters, their value and |
223 | presence is undefined and you cannot rely on them. Portable AnyEvent |
241 | presence is undefined and you cannot rely on them. Portable AnyEvent |
224 | callbacks cannot use arguments passed to time watcher callbacks. |
242 | callbacks cannot use arguments passed to time watcher callbacks. |
225 | |
243 | |
226 | 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 |
227 | parameter, "interval", as a strictly positive number (> 0), then the |
245 | parameter, "interval", as a strictly positive number (> 0), then the |
228 | callback will be invoked regularly at that interval (in fractional |
246 | callback will be invoked regularly at that interval (in fractional |
229 | seconds) after the first invocation. If "interval" is specified with a |
247 | seconds) after the first invocation. If "interval" is specified with a |
230 | 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. |
231 | |
249 | |
232 | The callback will be rescheduled before invoking the callback, but no |
250 | The callback will be rescheduled before invoking the callback, but no |
233 | 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 |
234 | is only approximate. |
252 | is only approximate. |
235 | |
253 | |
236 | Example: fire an event after 7.7 seconds. |
254 | Example: fire an event after 7.7 seconds. |
237 | |
255 | |
238 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
256 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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255 | |
273 | |
256 | 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, |
257 | they use absolute time internally. This makes a difference when your |
275 | they use absolute time internally. This makes a difference when your |
258 | 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 |
259 | 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 |
260 | 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 |
261 | finally fire. |
279 | finally fire. |
262 | |
280 | |
263 | AnyEvent cannot compensate for this. The only event loop that is |
281 | AnyEvent cannot compensate for this. The only event loop that is |
264 | conscious about these issues is EV, which offers both relative |
282 | conscious of these issues is EV, which offers both relative (ev_timer, |
265 | (ev_timer, based on true relative time) and absolute (ev_periodic, based |
283 | based on true relative time) and absolute (ev_periodic, based on |
266 | on wallclock time) timers. |
284 | wallclock time) timers. |
267 | |
285 | |
268 | AnyEvent always prefers relative timers, if available, matching the |
286 | AnyEvent always prefers relative timers, if available, matching the |
269 | AnyEvent API. |
287 | AnyEvent API. |
270 | |
288 | |
271 | AnyEvent has two additional methods that return the "current time": |
289 | AnyEvent has two additional methods that return the "current time": |
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290 | *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 |
291 | function to call when you want to know the current time.* |
309 | function to call when you want to know the current time.* |
292 | |
310 | |
293 | This function is also often faster then "AnyEvent->time", and thus |
311 | This function is also often faster then "AnyEvent->time", and thus |
294 | the preferred method if you want some timestamp (for example, |
312 | the preferred method if you want some timestamp (for example, |
295 | AnyEvent::Handle uses this to update it's activity timeouts). |
313 | AnyEvent::Handle uses this to update its activity timeouts). |
296 | |
314 | |
297 | 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 |
298 | exact with your timing, you can skip it without bad conscience. |
316 | exact with your timing; you can skip it without a bad conscience. |
299 | |
317 | |
300 | For a practical example of when these times differ, consider |
318 | For a practical example of when these times differ, consider |
301 | Event::Lib and EV and the following set-up: |
319 | Event::Lib and EV and the following set-up: |
302 | |
320 | |
303 | 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 |
304 | at time=500 (assume no other callbacks delay processing). In your |
322 | at time=500 (assume no other callbacks delay processing). In your |
305 | callback, you wait a second by executing "sleep 1" (blocking the |
323 | callback, you wait a second by executing "sleep 1" (blocking the |
306 | 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 |
307 | timer that fires after three seconds. |
325 | timer that fires after three seconds. |
308 | |
326 | |
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340 | time, which might affect timers and time-outs. |
358 | time, which might affect timers and time-outs. |
341 | |
359 | |
342 | When this is the case, you can call this method, which will update |
360 | When this is the case, you can call this method, which will update |
343 | the event loop's idea of "current time". |
361 | the event loop's idea of "current time". |
344 | |
362 | |
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363 | A typical example would be a script in a web server (e.g. |
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364 | "mod_perl") - when mod_perl executes the script, then the event loop |
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365 | will have the wrong idea about the "current time" (being potentially |
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366 | far in the past, when the script ran the last time). In that case |
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367 | you should arrange a call to "AnyEvent->now_update" each time the |
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368 | web server process wakes up again (e.g. at the start of your script, |
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369 | or in a handler). |
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370 | |
345 | Note that updating the time *might* cause some events to be handled. |
371 | Note that updating the time *might* cause some events to be handled. |
346 | |
372 | |
347 | SIGNAL WATCHERS |
373 | SIGNAL WATCHERS |
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374 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
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375 | |
348 | You can watch for signals using a signal watcher, "signal" is the signal |
376 | You can watch for signals using a signal watcher, "signal" is the signal |
349 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
377 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
350 | callback to be invoked whenever a signal occurs. |
378 | callback to be invoked whenever a signal occurs. |
351 | |
379 | |
352 | Although the callback might get passed parameters, their value and |
380 | Although the callback might get passed parameters, their value and |
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368 | |
396 | |
369 | Example: exit on SIGINT |
397 | Example: exit on SIGINT |
370 | |
398 | |
371 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
399 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
372 | |
400 | |
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401 | Restart Behaviour |
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402 | While restart behaviour is up to the event loop implementation, most |
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403 | will not restart syscalls (that includes Async::Interrupt and AnyEvent's |
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404 | pure perl implementation). |
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405 | |
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406 | Safe/Unsafe Signals |
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407 | Perl signals can be either "safe" (synchronous to opcode handling) or |
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408 | "unsafe" (asynchronous) - the former might get delayed indefinitely, the |
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409 | latter might corrupt your memory. |
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410 | |
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411 | AnyEvent signal handlers are, in addition, synchronous to the event |
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412 | loop, i.e. they will not interrupt your running perl program but will |
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413 | only be called as part of the normal event handling (just like timer, |
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414 | I/O etc. callbacks, too). |
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415 | |
373 | Signal Races, Delays and Workarounds |
416 | Signal Races, Delays and Workarounds |
374 | 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 |
375 | 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 |
376 | race-free signal handling in perl. AnyEvent will try to do it's best, |
419 | race-free signal handling in perl, requiring C libraries for this. |
377 | but in some cases, signals will be delayed. The maximum time a signal |
420 | AnyEvent will try to do its best, which means in some cases, signals |
378 | might be delayed is specified in $AnyEvent::MAX_SIGNAL_LATENCY (default: |
421 | will be delayed. The maximum time a signal might be delayed is specified |
379 | 10 seconds). This variable can be changed only before the first signal |
422 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
380 | watcher is created, and should be left alone otherwise. Higher values |
423 | can be changed only before the first signal watcher is created, and |
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424 | should be left alone otherwise. This variable determines how often |
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425 | AnyEvent polls for signals (in case a wake-up was missed). Higher values |
381 | will cause fewer spurious wake-ups, which is better for power and CPU |
426 | will cause fewer spurious wake-ups, which is better for power and CPU |
|
|
427 | saving. |
|
|
428 | |
382 | saving. All these problems can be avoided by installing the optional |
429 | All these problems can be avoided by installing the optional |
383 | Async::Interrupt module. This will not work with inherently broken event |
430 | Async::Interrupt module, which works with most event loops. It will not |
384 | loops such as Event or Event::Lib (and not with POE currently, as POE |
431 | work with inherently broken event loops such as Event or Event::Lib (and |
385 | does it's own workaround with one-second latency). With those, you just |
432 | not with POE currently, as POE does its own workaround with one-second |
386 | have to suffer the delays. |
433 | latency). For those, you just have to suffer the delays. |
387 | |
434 | |
388 | CHILD PROCESS WATCHERS |
435 | CHILD PROCESS WATCHERS |
|
|
436 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
|
|
437 | |
389 | 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. |
390 | |
439 | |
391 | The child process is specified by the "pid" argument (if set to 0, it |
440 | The child process is specified by the "pid" argument (on some backends, |
392 | watches for any child process exit). The watcher will triggered only |
441 | using 0 watches for any child process exit, on others this will croak). |
393 | when the child process has finished and an exit status is available, not |
442 | The watcher will be triggered only when the child process has finished |
394 | on any trace events (stopped/continued). |
443 | and an exit status is available, not on any trace events |
|
|
444 | (stopped/continued). |
395 | |
445 | |
396 | The callback will be called with the pid and exit status (as returned by |
446 | The callback will be called with the pid and exit status (as returned by |
397 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
447 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
398 | callback arguments. |
448 | callback arguments. |
399 | |
449 | |
… | |
… | |
438 | |
488 | |
439 | # do something else, then wait for process exit |
489 | # do something else, then wait for process exit |
440 | $done->recv; |
490 | $done->recv; |
441 | |
491 | |
442 | IDLE WATCHERS |
492 | IDLE WATCHERS |
443 | Sometimes there is a need to do something, but it is not so important to |
493 | $w = AnyEvent->idle (cb => <callback>); |
444 | do it instantly, but only when there is nothing better to do. This |
|
|
445 | "nothing better to do" is usually defined to be "no other events need |
|
|
446 | attention by the event loop". |
|
|
447 | |
494 | |
448 | Idle watchers ideally get invoked when the event loop has nothing better |
495 | This will repeatedly invoke the callback after the process becomes idle, |
449 | to do, just before it would block the process to wait for new events. |
496 | until either the watcher is destroyed or new events have been detected. |
450 | Instead of blocking, the idle watcher is invoked. |
|
|
451 | |
497 | |
452 | Most event loops unfortunately do not really support idle watchers (only |
498 | Idle watchers are useful when there is a need to do something, but it is |
|
|
499 | not so important (or wise) to do it instantly. The callback will be |
|
|
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. |
|
|
506 | |
|
|
507 | Unfortunately, most event loops do not really support idle watchers |
453 | 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, |
454 | will simply call the callback "from time to time". |
509 | AnyEvent will simply call the callback "from time to time". |
455 | |
510 | |
456 | 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 |
457 | is otherwise idle: |
512 | is otherwise idle: |
458 | |
513 | |
459 | my @lines; # read data |
514 | my @lines; # read data |
… | |
… | |
472 | } |
527 | } |
473 | }); |
528 | }); |
474 | }); |
529 | }); |
475 | |
530 | |
476 | CONDITION VARIABLES |
531 | CONDITION VARIABLES |
|
|
532 | $cv = AnyEvent->condvar; |
|
|
533 | |
|
|
534 | $cv->send (<list>); |
|
|
535 | my @res = $cv->recv; |
|
|
536 | |
477 | If you are familiar with some event loops you will know that all of them |
537 | If you are familiar with some event loops you will know that all of them |
478 | require you to run some blocking "loop", "run" or similar function that |
538 | require you to run some blocking "loop", "run" or similar function that |
479 | will actively watch for new events and call your callbacks. |
539 | will actively watch for new events and call your callbacks. |
480 | |
540 | |
481 | AnyEvent is slightly different: it expects somebody else to run the |
541 | AnyEvent is slightly different: it expects somebody else to run the |
482 | 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 |
483 | user). |
543 | user). |
484 | |
544 | |
485 | 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 |
486 | because they represent a condition that must become true. |
546 | they represent a condition that must become true. |
487 | |
547 | |
488 | 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. |
489 | |
549 | |
490 | Condition variables can be created by calling the "AnyEvent->condvar" |
550 | Condition variables can be created by calling the "AnyEvent->condvar" |
491 | method, usually without arguments. The only argument pair allowed is |
551 | method, usually without arguments. The only argument pair allowed is |
… | |
… | |
496 | After creation, the condition variable is "false" until it becomes |
556 | After creation, the condition variable is "false" until it becomes |
497 | "true" by calling the "send" method (or calling the condition variable |
557 | "true" by calling the "send" method (or calling the condition variable |
498 | 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 |
499 | the "->send" method). |
559 | the "->send" method). |
500 | |
560 | |
501 | Condition variables are similar to callbacks, except that you can |
561 | Since condition variables are the most complex part of the AnyEvent API, |
502 | 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 |
503 | in time where multiple outstanding events have been processed. And yet |
563 | you can connect to: |
504 | another way to call them is transactions - each condition variable can |
564 | |
505 | be used to represent a transaction, which finishes at some point and |
565 | * Condition variables are like callbacks - you can call them (and pass |
506 | delivers a result. And yet some people know them as "futures" - a |
566 | them instead of callbacks). Unlike callbacks however, you can also |
507 | 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. |
508 | |
582 | |
509 | Condition variables are very useful to signal that something has |
583 | Condition variables are very useful to signal that something has |
510 | 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 |
511 | requests, then a condition variable would be the ideal candidate to |
585 | requests, then a condition variable would be the ideal candidate to |
512 | 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 |
… | |
… | |
525 | |
599 | |
526 | 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 |
527 | 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 |
528 | (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 |
529 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
603 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
530 | it's "new" method in your own "new" method. |
604 | its "new" method in your own "new" method. |
531 | |
605 | |
532 | There are two "sides" to a condition variable - the "producer side" |
606 | There are two "sides" to a condition variable - the "producer side" |
533 | which eventually calls "-> send", and the "consumer side", which waits |
607 | which eventually calls "-> send", and the "consumer side", which waits |
534 | for the send to occur. |
608 | for the send to occur. |
535 | |
609 | |
536 | Example: wait for a timer. |
610 | Example: wait for a timer. |
537 | |
611 | |
538 | # wait till the result is ready |
612 | # condition: "wait till the timer is fired" |
539 | my $result_ready = AnyEvent->condvar; |
613 | my $timer_fired = AnyEvent->condvar; |
540 | |
614 | |
541 | # do something such as adding a timer |
615 | # create the timer - we could wait for, say |
542 | # or socket watcher the calls $result_ready->send |
616 | # a handle becomign ready, or even an |
543 | # when the "result" is ready. |
617 | # AnyEvent::HTTP request to finish, but |
544 | # in this case, we simply use a timer: |
618 | # in this case, we simply use a timer: |
545 | my $w = AnyEvent->timer ( |
619 | my $w = AnyEvent->timer ( |
546 | after => 1, |
620 | after => 1, |
547 | cb => sub { $result_ready->send }, |
621 | cb => sub { $timer_fired->send }, |
548 | ); |
622 | ); |
549 | |
623 | |
550 | # this "blocks" (while handling events) till the callback |
624 | # this "blocks" (while handling events) till the callback |
551 | # calls -<send |
625 | # calls ->send |
552 | $result_ready->recv; |
626 | $timer_fired->recv; |
553 | |
627 | |
554 | 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 |
555 | variables are also callable directly. |
629 | variables are also callable directly. |
556 | |
630 | |
557 | my $done = AnyEvent->condvar; |
631 | my $done = AnyEvent->condvar; |
… | |
… | |
595 | Condition variables are overloaded so one can call them directly (as |
669 | Condition variables are overloaded so one can call them directly (as |
596 | 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 |
597 | calling "send". |
671 | calling "send". |
598 | |
672 | |
599 | $cv->croak ($error) |
673 | $cv->croak ($error) |
600 | Similar to send, but causes all call's to "->recv" to invoke |
674 | Similar to send, but causes all calls to "->recv" to invoke |
601 | "Carp::croak" with the given error message/object/scalar. |
675 | "Carp::croak" with the given error message/object/scalar. |
602 | |
676 | |
603 | 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 |
604 | user/consumer. Doing it this way instead of calling "croak" directly |
678 | user/consumer. Doing it this way instead of calling "croak" directly |
605 | delays the error detetcion, but has the overwhelmign advantage that |
679 | delays the error detection, but has the overwhelming advantage that |
606 | 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, |
607 | 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 |
608 | code causing the problem. |
682 | code causing the problem. |
609 | |
683 | |
610 | $cv->begin ([group callback]) |
684 | $cv->begin ([group callback]) |
611 | $cv->end |
685 | $cv->end |
612 | These two methods can be used to combine many transactions/events |
686 | These two methods can be used to combine many transactions/events |
613 | into one. For example, a function that pings many hosts in parallel |
687 | into one. For example, a function that pings many hosts in parallel |
614 | might want to use a condition variable for the whole process. |
688 | might want to use a condition variable for the whole process. |
615 | |
689 | |
616 | Every call to "->begin" will increment a counter, and every call to |
690 | Every call to "->begin" will increment a counter, and every call to |
617 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
691 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
618 | (last) callback passed to "begin" will be executed. That callback is |
692 | (last) callback passed to "begin" will be executed, passing the |
619 | *supposed* to call "->send", but that is not required. If no |
693 | condvar as first argument. That callback is *supposed* to call |
|
|
694 | "->send", but that is not required. If no group callback was set, |
620 | callback was set, "send" will be called without any arguments. |
695 | "send" will be called without any arguments. |
621 | |
696 | |
622 | You can think of "$cv->send" giving you an OR condition (one call |
697 | You can think of "$cv->send" giving you an OR condition (one call |
623 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
698 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
624 | condition (all "begin" calls must be "end"'ed before the condvar |
699 | condition (all "begin" calls must be "end"'ed before the condvar |
625 | sends). |
700 | sends). |
… | |
… | |
648 | 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 |
649 | "end" before sending. |
724 | "end" before sending. |
650 | |
725 | |
651 | The ping example mentioned above is slightly more complicated, as |
726 | The ping example mentioned above is slightly more complicated, as |
652 | 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 |
653 | that are begung can potentially be zero: |
728 | that are begun can potentially be zero: |
654 | |
729 | |
655 | my $cv = AnyEvent->condvar; |
730 | my $cv = AnyEvent->condvar; |
656 | |
731 | |
657 | my %result; |
732 | my %result; |
658 | $cv->begin (sub { $cv->send (\%result) }); |
733 | $cv->begin (sub { shift->send (\%result) }); |
659 | |
734 | |
660 | for my $host (@list_of_hosts) { |
735 | for my $host (@list_of_hosts) { |
661 | $cv->begin; |
736 | $cv->begin; |
662 | ping_host_then_call_callback $host, sub { |
737 | ping_host_then_call_callback $host, sub { |
663 | $result{$host} = ...; |
738 | $result{$host} = ...; |
… | |
… | |
679 | 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 |
680 | 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 |
681 | (the loop doesn't execute once). |
756 | (the loop doesn't execute once). |
682 | |
757 | |
683 | 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 |
684 | potentially none) subrequests: use an outer "begin"/"end" pair to |
759 | potentially zero) subrequests: use an outer "begin"/"end" pair to |
685 | 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, |
686 | for each subrequest you start, call "begin" and for each subrequest |
761 | for each subrequest you start, call "begin" and for each subrequest |
687 | you finish, call "end". |
762 | you finish, call "end". |
688 | |
763 | |
689 | METHODS FOR CONSUMERS |
764 | METHODS FOR CONSUMERS |
690 | 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 |
691 | awaits the condition. |
766 | awaits the condition. |
692 | |
767 | |
693 | $cv->recv |
768 | $cv->recv |
694 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
769 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
695 | have been called on c<$cv>, while servicing other watchers normally. |
770 | have been called on $cv, while servicing other watchers normally. |
696 | |
771 | |
697 | 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 |
698 | but will return immediately. |
773 | but will return immediately. |
699 | |
774 | |
700 | 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 |
… | |
… | |
717 | example, by coupling condition variables with some kind of request |
792 | example, by coupling condition variables with some kind of request |
718 | results and supporting callbacks so the caller knows that getting |
793 | results and supporting callbacks so the caller knows that getting |
719 | the result will not block, while still supporting blocking waits if |
794 | the result will not block, while still supporting blocking waits if |
720 | the caller so desires). |
795 | the caller so desires). |
721 | |
796 | |
722 | 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 |
723 | only calling "->recv" from within that callback (or at a later |
798 | only calling "->recv" from within that callback (or at a later |
724 | 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 |
725 | blocking waits otherwise. |
800 | blocking waits otherwise. |
726 | |
801 | |
727 | $bool = $cv->ready |
802 | $bool = $cv->ready |
… | |
… | |
732 | This is a mutator function that returns the callback set and |
807 | This is a mutator function that returns the callback set and |
733 | optionally replaces it before doing so. |
808 | optionally replaces it before doing so. |
734 | |
809 | |
735 | The callback will be called when the condition becomes "true", i.e. |
810 | The callback will be called when the condition becomes "true", i.e. |
736 | when "send" or "croak" are called, with the only argument being the |
811 | when "send" or "croak" are called, with the only argument being the |
737 | condition variable itself. Calling "recv" inside the callback or at |
812 | condition variable itself. If the condition is already true, the |
|
|
813 | callback is called immediately when it is set. Calling "recv" inside |
738 | any later time is guaranteed not to block. |
814 | the callback or at any later time is guaranteed not to block. |
739 | |
815 | |
740 | SUPPORTED EVENT LOOPS/BACKENDS |
816 | SUPPORTED EVENT LOOPS/BACKENDS |
741 | The available backend classes are (every class has its own manpage): |
817 | The available backend classes are (every class has its own manpage): |
742 | |
818 | |
743 | 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. |
744 | EV is the preferred backend when no other event loop seems to be in |
820 | EV is the preferred backend when no other event loop seems to be in |
745 | use. If EV is not installed, then AnyEvent will try Event, and, |
821 | use. If EV is not installed, then AnyEvent will fall back to its own |
746 | failing that, will fall back to its own pure-perl implementation, |
822 | pure-perl implementation, which is available everywhere as it comes |
747 | which is available everywhere as it comes with AnyEvent itself. |
823 | with AnyEvent itself. |
748 | |
824 | |
749 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
825 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
750 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
751 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
826 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
752 | |
827 | |
753 | Backends that are transparently being picked up when they are used. |
828 | Backends that are transparently being picked up when they are used. |
754 | 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 |
755 | 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 |
756 | is using them. This means that AnyEvent will automatically pick the |
831 | using them. This means that AnyEvent will automatically pick the |
757 | right backend when the main program loads an event module before |
832 | right backend when the main program loads an event module before |
758 | anything starts to create watchers. Nothing special needs to be done |
833 | anything starts to create watchers. Nothing special needs to be done |
759 | by the main program. |
834 | by the main program. |
760 | |
835 | |
|
|
836 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
761 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
837 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
762 | AnyEvent::Impl::Tk based on Tk, very broken. |
838 | AnyEvent::Impl::Tk based on Tk, very broken. |
763 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
839 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
764 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
840 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
841 | AnyEvent::Impl::Irssi used when running within irssi. |
765 | |
842 | |
766 | Backends with special needs. |
843 | Backends with special needs. |
767 | Qt requires the Qt::Application to be instantiated first, but will |
844 | Qt requires the Qt::Application to be instantiated first, but will |
768 | otherwise be picked up automatically. As long as the main program |
845 | otherwise be picked up automatically. As long as the main program |
769 | instantiates the application before any AnyEvent watchers are |
846 | instantiates the application before any AnyEvent watchers are |
… | |
… | |
773 | |
850 | |
774 | Support for IO::Async can only be partial, as it is too broken and |
851 | Support for IO::Async can only be partial, as it is too broken and |
775 | architecturally limited to even support the AnyEvent API. It also is |
852 | architecturally limited to even support the AnyEvent API. It also is |
776 | the only event loop that needs the loop to be set explicitly, so it |
853 | the only event loop that needs the loop to be set explicitly, so it |
777 | can only be used by a main program knowing about AnyEvent. See |
854 | can only be used by a main program knowing about AnyEvent. See |
778 | AnyEvent::Impl::Async for the gory details. |
855 | AnyEvent::Impl::IOAsync for the gory details. |
779 | |
856 | |
780 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
857 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
781 | |
858 | |
782 | Event loops that are indirectly supported via other backends. |
859 | Event loops that are indirectly supported via other backends. |
783 | Some event loops can be supported via other modules: |
860 | Some event loops can be supported via other modules: |
… | |
… | |
804 | Contains "undef" until the first watcher is being created, before |
881 | Contains "undef" until the first watcher is being created, before |
805 | the backend has been autodetected. |
882 | the backend has been autodetected. |
806 | |
883 | |
807 | Afterwards it contains the event model that is being used, which is |
884 | Afterwards it contains the event model that is being used, which is |
808 | the name of the Perl class implementing the model. This class is |
885 | the name of the Perl class implementing the model. This class is |
809 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
886 | usually one of the "AnyEvent::Impl::xxx" modules, but can be any |
810 | other class in the case AnyEvent has been extended at runtime (e.g. |
887 | other class in the case AnyEvent has been extended at runtime (e.g. |
811 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
888 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
812 | |
889 | |
813 | AnyEvent::detect |
890 | AnyEvent::detect |
814 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
891 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
815 | if necessary. You should only call this function right before you |
892 | if necessary. You should only call this function right before you |
816 | would have created an AnyEvent watcher anyway, that is, as late as |
893 | would have created an AnyEvent watcher anyway, that is, as late as |
817 | possible at runtime, and not e.g. while initialising of your module. |
894 | possible at runtime, and not e.g. during initialisation of your |
|
|
895 | module. |
818 | |
896 | |
819 | If you need to do some initialisation before AnyEvent watchers are |
897 | If you need to do some initialisation before AnyEvent watchers are |
820 | created, use "post_detect". |
898 | created, use "post_detect". |
821 | |
899 | |
822 | $guard = AnyEvent::post_detect { BLOCK } |
900 | $guard = AnyEvent::post_detect { BLOCK } |
823 | Arranges for the code block to be executed as soon as the event |
901 | Arranges for the code block to be executed as soon as the event |
824 | model is autodetected (or immediately if this has already happened). |
902 | model is autodetected (or immediately if that has already happened). |
825 | |
903 | |
826 | The block will be executed *after* the actual backend has been |
904 | The block will be executed *after* the actual backend has been |
827 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
905 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
828 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
906 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
829 | other initialisations - see the sources of AnyEvent::Strict or |
907 | other initialisations - see the sources of AnyEvent::Strict or |
… | |
… | |
834 | creates and installs the global IO::AIO watcher in a "post_detect" |
912 | creates and installs the global IO::AIO watcher in a "post_detect" |
835 | block to avoid autodetecting the event module at load time. |
913 | block to avoid autodetecting the event module at load time. |
836 | |
914 | |
837 | If called in scalar or list context, then it creates and returns an |
915 | If called in scalar or list context, then it creates and returns an |
838 | object that automatically removes the callback again when it is |
916 | object that automatically removes the callback again when it is |
|
|
917 | destroyed (or "undef" when the hook was immediately executed). See |
839 | destroyed. See Coro::BDB for a case where this is useful. |
918 | AnyEvent::AIO for a case where this is useful. |
|
|
919 | |
|
|
920 | Example: Create a watcher for the IO::AIO module and store it in |
|
|
921 | $WATCHER, but do so only do so after the event loop is initialised. |
|
|
922 | |
|
|
923 | our WATCHER; |
|
|
924 | |
|
|
925 | my $guard = AnyEvent::post_detect { |
|
|
926 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
|
|
927 | }; |
|
|
928 | |
|
|
929 | # the ||= is important in case post_detect immediately runs the block, |
|
|
930 | # as to not clobber the newly-created watcher. assigning both watcher and |
|
|
931 | # post_detect guard to the same variable has the advantage of users being |
|
|
932 | # able to just C<undef $WATCHER> if the watcher causes them grief. |
|
|
933 | |
|
|
934 | $WATCHER ||= $guard; |
840 | |
935 | |
841 | @AnyEvent::post_detect |
936 | @AnyEvent::post_detect |
842 | If there are any code references in this array (you can "push" to it |
937 | If there are any code references in this array (you can "push" to it |
843 | before or after loading AnyEvent), then they will called directly |
938 | before or after loading AnyEvent), then they will be called directly |
844 | after the event loop has been chosen. |
939 | after the event loop has been chosen. |
845 | |
940 | |
846 | You should check $AnyEvent::MODEL before adding to this array, |
941 | You should check $AnyEvent::MODEL before adding to this array, |
847 | though: if it is defined then the event loop has already been |
942 | though: if it is defined then the event loop has already been |
848 | detected, and the array will be ignored. |
943 | detected, and the array will be ignored. |
849 | |
944 | |
850 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
945 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
851 | allows it,as it takes care of these details. |
946 | allows it, as it takes care of these details. |
852 | |
947 | |
853 | This variable is mainly useful for modules that can do something |
948 | This variable is mainly useful for modules that can do something |
854 | useful when AnyEvent is used and thus want to know when it is |
949 | useful when AnyEvent is used and thus want to know when it is |
855 | initialised, but do not need to even load it by default. This array |
950 | initialised, but do not need to even load it by default. This array |
856 | provides the means to hook into AnyEvent passively, without loading |
951 | provides the means to hook into AnyEvent passively, without loading |
857 | it. |
952 | it. |
858 | |
953 | |
|
|
954 | Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used |
|
|
955 | together, you could put this into Coro (this is the actual code used |
|
|
956 | by Coro to accomplish this): |
|
|
957 | |
|
|
958 | if (defined $AnyEvent::MODEL) { |
|
|
959 | # AnyEvent already initialised, so load Coro::AnyEvent |
|
|
960 | require Coro::AnyEvent; |
|
|
961 | } else { |
|
|
962 | # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent |
|
|
963 | # as soon as it is |
|
|
964 | push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; |
|
|
965 | } |
|
|
966 | |
859 | WHAT TO DO IN A MODULE |
967 | WHAT TO DO IN A MODULE |
860 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
968 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
861 | freely, but you should not load a specific event module or rely on it. |
969 | freely, but you should not load a specific event module or rely on it. |
862 | |
970 | |
863 | Be careful when you create watchers in the module body - AnyEvent will |
971 | Be careful when you create watchers in the module body - AnyEvent will |
… | |
… | |
870 | stall the whole program, and the whole point of using events is to stay |
978 | stall the whole program, and the whole point of using events is to stay |
871 | interactive. |
979 | interactive. |
872 | |
980 | |
873 | It is fine, however, to call "->recv" when the user of your module |
981 | It is fine, however, to call "->recv" when the user of your module |
874 | requests it (i.e. if you create a http request object ad have a method |
982 | requests it (i.e. if you create a http request object ad have a method |
875 | called "results" that returns the results, it should call "->recv" |
983 | called "results" that returns the results, it may call "->recv" freely, |
876 | freely, as the user of your module knows what she is doing. always). |
984 | as the user of your module knows what she is doing. Always). |
877 | |
985 | |
878 | WHAT TO DO IN THE MAIN PROGRAM |
986 | WHAT TO DO IN THE MAIN PROGRAM |
879 | There will always be a single main program - the only place that should |
987 | There will always be a single main program - the only place that should |
880 | dictate which event model to use. |
988 | dictate which event model to use. |
881 | |
989 | |
882 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
990 | If the program is not event-based, it need not do anything special, even |
883 | do anything special (it does not need to be event-based) and let |
991 | when it depends on a module that uses an AnyEvent. If the program itself |
884 | AnyEvent decide which implementation to chose if some module relies on |
992 | uses AnyEvent, but does not care which event loop is used, all it needs |
885 | it. |
993 | to do is "use AnyEvent". In either case, AnyEvent will choose the best |
|
|
994 | available loop implementation. |
886 | |
995 | |
887 | If the main program relies on a specific event model - for example, in |
996 | If the main program relies on a specific event model - for example, in |
888 | Gtk2 programs you have to rely on the Glib module - you should load the |
997 | Gtk2 programs you have to rely on the Glib module - you should load the |
889 | event module before loading AnyEvent or any module that uses it: |
998 | event module before loading AnyEvent or any module that uses it: |
890 | generally speaking, you should load it as early as possible. The reason |
999 | generally speaking, you should load it as early as possible. The reason |
891 | is that modules might create watchers when they are loaded, and AnyEvent |
1000 | is that modules might create watchers when they are loaded, and AnyEvent |
892 | will decide on the event model to use as soon as it creates watchers, |
1001 | will decide on the event model to use as soon as it creates watchers, |
893 | and it might chose the wrong one unless you load the correct one |
1002 | and it might choose the wrong one unless you load the correct one |
894 | yourself. |
1003 | yourself. |
895 | |
1004 | |
896 | You can chose to use a pure-perl implementation by loading the |
1005 | You can chose to use a pure-perl implementation by loading the |
897 | "AnyEvent::Impl::Perl" module, which gives you similar behaviour |
1006 | "AnyEvent::Impl::Perl" module, which gives you similar behaviour |
898 | everywhere, but letting AnyEvent chose the model is generally better. |
1007 | everywhere, but letting AnyEvent chose the model is generally better. |
… | |
… | |
915 | |
1024 | |
916 | OTHER MODULES |
1025 | OTHER MODULES |
917 | The following is a non-exhaustive list of additional modules that use |
1026 | The following is a non-exhaustive list of additional modules that use |
918 | AnyEvent as a client and can therefore be mixed easily with other |
1027 | AnyEvent as a client and can therefore be mixed easily with other |
919 | AnyEvent modules and other event loops in the same program. Some of the |
1028 | AnyEvent modules and other event loops in the same program. Some of the |
920 | modules come with AnyEvent, most are available via CPAN. |
1029 | modules come as part of AnyEvent, the others are available via CPAN. |
921 | |
1030 | |
922 | AnyEvent::Util |
1031 | AnyEvent::Util |
923 | Contains various utility functions that replace often-used but |
1032 | Contains various utility functions that replace often-used blocking |
924 | blocking functions such as "inet_aton" by event-/callback-based |
1033 | functions such as "inet_aton" with event/callback-based versions. |
925 | versions. |
|
|
926 | |
1034 | |
927 | AnyEvent::Socket |
1035 | AnyEvent::Socket |
928 | Provides various utility functions for (internet protocol) sockets, |
1036 | Provides various utility functions for (internet protocol) sockets, |
929 | addresses and name resolution. Also functions to create non-blocking |
1037 | addresses and name resolution. Also functions to create non-blocking |
930 | tcp connections or tcp servers, with IPv6 and SRV record support and |
1038 | tcp connections or tcp servers, with IPv6 and SRV record support and |
931 | more. |
1039 | more. |
932 | |
1040 | |
933 | AnyEvent::Handle |
1041 | AnyEvent::Handle |
934 | Provide read and write buffers, manages watchers for reads and |
1042 | Provide read and write buffers, manages watchers for reads and |
935 | writes, supports raw and formatted I/O, I/O queued and fully |
1043 | writes, supports raw and formatted I/O, I/O queued and fully |
936 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
1044 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS). |
937 | |
1045 | |
938 | AnyEvent::DNS |
1046 | AnyEvent::DNS |
939 | Provides rich asynchronous DNS resolver capabilities. |
1047 | Provides rich asynchronous DNS resolver capabilities. |
940 | |
1048 | |
|
|
1049 | AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, |
|
|
1050 | AnyEvent::IGS, AnyEvent::FCP |
|
|
1051 | Implement event-based interfaces to the protocols of the same name |
|
|
1052 | (for the curious, IGS is the International Go Server and FCP is the |
|
|
1053 | Freenet Client Protocol). |
|
|
1054 | |
|
|
1055 | AnyEvent::Handle::UDP |
|
|
1056 | Here be danger! |
|
|
1057 | |
|
|
1058 | As Pauli would put it, "Not only is it not right, it's not even |
|
|
1059 | wrong!" - there are so many things wrong with AnyEvent::Handle::UDP, |
|
|
1060 | most notably its use of a stream-based API with a protocol that |
|
|
1061 | isn't streamable, that the only way to improve it is to delete it. |
|
|
1062 | |
|
|
1063 | It features data corruption (but typically only under load) and |
|
|
1064 | general confusion. On top, the author is not only clueless about UDP |
|
|
1065 | but also fact-resistant - some gems of his understanding: "connect |
|
|
1066 | doesn't work with UDP", "UDP packets are not IP packets", "UDP only |
|
|
1067 | has datagrams, not packets", "I don't need to implement proper error |
|
|
1068 | checking as UDP doesn't support error checking" and so on - he |
|
|
1069 | doesn't even understand what's wrong with his module when it is |
|
|
1070 | explained to him. |
|
|
1071 | |
941 | AnyEvent::HTTP |
1072 | AnyEvent::DBI |
942 | A simple-to-use HTTP library that is capable of making a lot of |
1073 | Executes DBI requests asynchronously in a proxy process for you, |
943 | concurrent HTTP requests. |
1074 | notifying you in an event-based way when the operation is finished. |
|
|
1075 | |
|
|
1076 | AnyEvent::AIO |
|
|
1077 | Truly asynchronous (as opposed to non-blocking) I/O, should be in |
|
|
1078 | the toolbox of every event programmer. AnyEvent::AIO transparently |
|
|
1079 | fuses IO::AIO and AnyEvent together, giving AnyEvent access to |
|
|
1080 | event-based file I/O, and much more. |
944 | |
1081 | |
945 | AnyEvent::HTTPD |
1082 | AnyEvent::HTTPD |
946 | Provides a simple web application server framework. |
1083 | A simple embedded webserver. |
947 | |
1084 | |
948 | AnyEvent::FastPing |
1085 | AnyEvent::FastPing |
949 | The fastest ping in the west. |
1086 | The fastest ping in the west. |
950 | |
1087 | |
951 | AnyEvent::DBI |
|
|
952 | Executes DBI requests asynchronously in a proxy process. |
|
|
953 | |
|
|
954 | AnyEvent::AIO |
|
|
955 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
956 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
957 | together. |
|
|
958 | |
|
|
959 | AnyEvent::BDB |
|
|
960 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
961 | fuses BDB and AnyEvent together. |
|
|
962 | |
|
|
963 | AnyEvent::GPSD |
|
|
964 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
965 | information. |
|
|
966 | |
|
|
967 | AnyEvent::IRC |
|
|
968 | AnyEvent based IRC client module family (replacing the older |
|
|
969 | Net::IRC3). |
|
|
970 | |
|
|
971 | AnyEvent::XMPP |
|
|
972 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
973 | older Net::XMPP2>. |
|
|
974 | |
|
|
975 | AnyEvent::IGS |
|
|
976 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
977 | App::IGS). |
|
|
978 | |
|
|
979 | Net::FCP |
|
|
980 | AnyEvent-based implementation of the Freenet Client Protocol, |
|
|
981 | birthplace of AnyEvent. |
|
|
982 | |
|
|
983 | Event::ExecFlow |
|
|
984 | High level API for event-based execution flow control. |
|
|
985 | |
|
|
986 | Coro |
1088 | Coro |
987 | Has special support for AnyEvent via Coro::AnyEvent. |
1089 | Has special support for AnyEvent via Coro::AnyEvent. |
|
|
1090 | |
|
|
1091 | SIMPLIFIED AE API |
|
|
1092 | Starting with version 5.0, AnyEvent officially supports a second, much |
|
|
1093 | simpler, API that is designed to reduce the calling, typing and memory |
|
|
1094 | overhead by using function call syntax and a fixed number of parameters. |
|
|
1095 | |
|
|
1096 | See the AE manpage for details. |
988 | |
1097 | |
989 | ERROR AND EXCEPTION HANDLING |
1098 | ERROR AND EXCEPTION HANDLING |
990 | In general, AnyEvent does not do any error handling - it relies on the |
1099 | In general, AnyEvent does not do any error handling - it relies on the |
991 | caller to do that if required. The AnyEvent::Strict module (see also the |
1100 | caller to do that if required. The AnyEvent::Strict module (see also the |
992 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
1101 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
… | |
… | |
1033 | thoroughly check the arguments passed to most method calls. If it |
1142 | thoroughly check the arguments passed to most method calls. If it |
1034 | finds any problems, it will croak. |
1143 | finds any problems, it will croak. |
1035 | |
1144 | |
1036 | In other words, enables "strict" mode. |
1145 | In other words, enables "strict" mode. |
1037 | |
1146 | |
1038 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
1147 | Unlike "use strict" (or its modern cousin, "use common::sense", it |
1039 | is definitely recommended to keep it off in production. Keeping |
1148 | is definitely recommended to keep it off in production. Keeping |
1040 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1149 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1041 | programs can be very useful, however. |
1150 | programs can be very useful, however. |
1042 | |
1151 | |
1043 | "PERL_ANYEVENT_MODEL" |
1152 | "PERL_ANYEVENT_MODEL" |
… | |
… | |
1171 | warn "read: $input\n"; # output what has been read |
1280 | warn "read: $input\n"; # output what has been read |
1172 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
1281 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
1173 | }, |
1282 | }, |
1174 | ); |
1283 | ); |
1175 | |
1284 | |
1176 | my $time_watcher; # can only be used once |
|
|
1177 | |
|
|
1178 | sub new_timer { |
|
|
1179 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1285 | my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub { |
1180 | warn "timeout\n"; # print 'timeout' about every second |
1286 | warn "timeout\n"; # print 'timeout' at most every second |
1181 | &new_timer; # and restart the time |
|
|
1182 | }); |
|
|
1183 | } |
1287 | }); |
1184 | |
|
|
1185 | new_timer; # create first timer |
|
|
1186 | |
1288 | |
1187 | $cv->recv; # wait until user enters /^q/i |
1289 | $cv->recv; # wait until user enters /^q/i |
1188 | |
1290 | |
1189 | REAL-WORLD EXAMPLE |
1291 | REAL-WORLD EXAMPLE |
1190 | Consider the Net::FCP module. It features (among others) the following |
1292 | Consider the Net::FCP module. It features (among others) the following |
… | |
… | |
1262 | |
1364 | |
1263 | The actual code goes further and collects all errors ("die"s, |
1365 | The actual code goes further and collects all errors ("die"s, |
1264 | exceptions) that occurred during request processing. The "result" method |
1366 | exceptions) that occurred during request processing. The "result" method |
1265 | detects whether an exception as thrown (it is stored inside the $txn |
1367 | detects whether an exception as thrown (it is stored inside the $txn |
1266 | object) and just throws the exception, which means connection errors and |
1368 | object) and just throws the exception, which means connection errors and |
1267 | other problems get reported tot he code that tries to use the result, |
1369 | other problems get reported to the code that tries to use the result, |
1268 | not in a random callback. |
1370 | not in a random callback. |
1269 | |
1371 | |
1270 | All of this enables the following usage styles: |
1372 | All of this enables the following usage styles: |
1271 | |
1373 | |
1272 | 1. Blocking: |
1374 | 1. Blocking: |
… | |
… | |
1317 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1419 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1318 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1420 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1319 | which it is), lets them fire exactly once and destroys them again. |
1421 | which it is), lets them fire exactly once and destroys them again. |
1320 | |
1422 | |
1321 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1423 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1322 | distribution. |
1424 | distribution. It uses the AE interface, which makes a real difference |
|
|
1425 | for the EV and Perl backends only. |
1323 | |
1426 | |
1324 | Explanation of the columns |
1427 | Explanation of the columns |
1325 | *watcher* is the number of event watchers created/destroyed. Since |
1428 | *watcher* is the number of event watchers created/destroyed. Since |
1326 | different event models feature vastly different performances, each event |
1429 | different event models feature vastly different performances, each event |
1327 | loop was given a number of watchers so that overall runtime is |
1430 | loop was given a number of watchers so that overall runtime is |
… | |
… | |
1346 | *destroy* is the time, in microseconds, that it takes to destroy a |
1449 | *destroy* is the time, in microseconds, that it takes to destroy a |
1347 | single watcher. |
1450 | single watcher. |
1348 | |
1451 | |
1349 | Results |
1452 | Results |
1350 | name watchers bytes create invoke destroy comment |
1453 | name watchers bytes create invoke destroy comment |
1351 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
1454 | EV/EV 100000 223 0.47 0.43 0.27 EV native interface |
1352 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1455 | EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers |
1353 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1456 | Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal |
1354 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1457 | Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation |
1355 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1458 | Event/Event 16000 516 31.16 31.84 0.82 Event native interface |
1356 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1459 | Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers |
1357 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
1460 | IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll |
1358 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
1461 | IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll |
1359 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1462 | Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour |
1360 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1463 | Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers |
1361 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1464 | POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event |
1362 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1465 | POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select |
1363 | |
1466 | |
1364 | Discussion |
1467 | Discussion |
1365 | The benchmark does *not* measure scalability of the event loop very |
1468 | The benchmark does *not* measure scalability of the event loop very |
1366 | well. For example, a select-based event loop (such as the pure perl one) |
1469 | well. For example, a select-based event loop (such as the pure perl one) |
1367 | can never compete with an event loop that uses epoll when the number of |
1470 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1378 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1481 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1379 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
1482 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
1380 | CPU cycles with POE. |
1483 | CPU cycles with POE. |
1381 | |
1484 | |
1382 | "EV" is the sole leader regarding speed and memory use, which are both |
1485 | "EV" is the sole leader regarding speed and memory use, which are both |
1383 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
1486 | maximal/minimal, respectively. When using the AE API there is zero |
|
|
1487 | overhead (when going through the AnyEvent API create is about 5-6 times |
|
|
1488 | slower, with other times being equal, so still uses far less memory than |
1384 | far less memory than any other event loop and is still faster than Event |
1489 | any other event loop and is still faster than Event natively). |
1385 | natively. |
|
|
1386 | |
1490 | |
1387 | The pure perl implementation is hit in a few sweet spots (both the |
1491 | The pure perl implementation is hit in a few sweet spots (both the |
1388 | constant timeout and the use of a single fd hit optimisations in the |
1492 | constant timeout and the use of a single fd hit optimisations in the |
1389 | perl interpreter and the backend itself). Nevertheless this shows that |
1493 | perl interpreter and the backend itself). Nevertheless this shows that |
1390 | it adds very little overhead in itself. Like any select-based backend |
1494 | it adds very little overhead in itself. Like any select-based backend |
… | |
… | |
1460 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1564 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1461 | 100 (1%) are active. This mirrors the activity of large servers with |
1565 | 100 (1%) are active. This mirrors the activity of large servers with |
1462 | many connections, most of which are idle at any one point in time. |
1566 | many connections, most of which are idle at any one point in time. |
1463 | |
1567 | |
1464 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1568 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1465 | distribution. |
1569 | distribution. It uses the AE interface, which makes a real difference |
|
|
1570 | for the EV and Perl backends only. |
1466 | |
1571 | |
1467 | Explanation of the columns |
1572 | Explanation of the columns |
1468 | *sockets* is the number of sockets, and twice the number of "servers" |
1573 | *sockets* is the number of sockets, and twice the number of "servers" |
1469 | (as each server has a read and write socket end). |
1574 | (as each server has a read and write socket end). |
1470 | |
1575 | |
… | |
… | |
1476 | forwarding it to another server. This includes deleting the old timeout |
1581 | forwarding it to another server. This includes deleting the old timeout |
1477 | and creating a new one that moves the timeout into the future. |
1582 | and creating a new one that moves the timeout into the future. |
1478 | |
1583 | |
1479 | Results |
1584 | Results |
1480 | name sockets create request |
1585 | name sockets create request |
1481 | EV 20000 69.01 11.16 |
1586 | EV 20000 62.66 7.99 |
1482 | Perl 20000 73.32 35.87 |
1587 | Perl 20000 68.32 32.64 |
1483 | IOAsync 20000 157.00 98.14 epoll |
1588 | IOAsync 20000 174.06 101.15 epoll |
1484 | IOAsync 20000 159.31 616.06 poll |
1589 | IOAsync 20000 174.67 610.84 poll |
1485 | Event 20000 212.62 257.32 |
1590 | Event 20000 202.69 242.91 |
1486 | Glib 20000 651.16 1896.30 |
1591 | Glib 20000 557.01 1689.52 |
1487 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1592 | POE 20000 341.54 12086.32 uses POE::Loop::Event |
1488 | |
1593 | |
1489 | Discussion |
1594 | Discussion |
1490 | This benchmark *does* measure scalability and overall performance of the |
1595 | This benchmark *does* measure scalability and overall performance of the |
1491 | particular event loop. |
1596 | particular event loop. |
1492 | |
1597 | |
… | |
… | |
1605 | As you can see, the AnyEvent + EV combination even beats the |
1710 | As you can see, the AnyEvent + EV combination even beats the |
1606 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
1711 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
1607 | backend easily beats IO::Lambda and POE. |
1712 | backend easily beats IO::Lambda and POE. |
1608 | |
1713 | |
1609 | And even the 100% non-blocking version written using the high-level (and |
1714 | And even the 100% non-blocking version written using the high-level (and |
1610 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
1715 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda |
1611 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
1716 | higher level ("unoptimised") abstractions by a large margin, even though |
1612 | in a non-blocking way. |
1717 | it does all of DNS, tcp-connect and socket I/O in a non-blocking way. |
1613 | |
1718 | |
1614 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
1719 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
1615 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
1720 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
1616 | part of the IO::lambda distribution and were used without any changes. |
1721 | part of the IO::Lambda distribution and were used without any changes. |
1617 | |
1722 | |
1618 | SIGNALS |
1723 | SIGNALS |
1619 | AnyEvent currently installs handlers for these signals: |
1724 | AnyEvent currently installs handlers for these signals: |
1620 | |
1725 | |
1621 | SIGCHLD |
1726 | SIGCHLD |
… | |
… | |
1643 | |
1748 | |
1644 | Feel free to install your own handler, or reset it to defaults. |
1749 | Feel free to install your own handler, or reset it to defaults. |
1645 | |
1750 | |
1646 | RECOMMENDED/OPTIONAL MODULES |
1751 | RECOMMENDED/OPTIONAL MODULES |
1647 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
1752 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
1648 | it's built-in modules) are required to use it. |
1753 | its built-in modules) are required to use it. |
1649 | |
1754 | |
1650 | That does not mean that AnyEvent won't take advantage of some additional |
1755 | That does not mean that AnyEvent won't take advantage of some additional |
1651 | modules if they are installed. |
1756 | modules if they are installed. |
1652 | |
1757 | |
1653 | This section epxlains which additional modules will be used, and how |
1758 | This section explains which additional modules will be used, and how |
1654 | they affect AnyEvent's operetion. |
1759 | they affect AnyEvent's operation. |
1655 | |
1760 | |
1656 | Async::Interrupt |
1761 | Async::Interrupt |
1657 | This slightly arcane module is used to implement fast signal |
1762 | This slightly arcane module is used to implement fast signal |
1658 | handling: To my knowledge, there is no way to do completely |
1763 | handling: To my knowledge, there is no way to do completely |
1659 | race-free and quick signal handling in pure perl. To ensure that |
1764 | race-free and quick signal handling in pure perl. To ensure that |
… | |
… | |
1662 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
1767 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
1663 | |
1768 | |
1664 | If this module is available, then it will be used to implement |
1769 | If this module is available, then it will be used to implement |
1665 | signal catching, which means that signals will not be delayed, and |
1770 | signal catching, which means that signals will not be delayed, and |
1666 | the event loop will not be interrupted regularly, which is more |
1771 | the event loop will not be interrupted regularly, which is more |
1667 | efficient (And good for battery life on laptops). |
1772 | efficient (and good for battery life on laptops). |
1668 | |
1773 | |
1669 | This affects not just the pure-perl event loop, but also other event |
1774 | This affects not just the pure-perl event loop, but also other event |
1670 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
1775 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
1671 | |
1776 | |
1672 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
1777 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
… | |
… | |
1682 | clock is available, can take avdantage of advanced kernel interfaces |
1787 | clock is available, can take avdantage of advanced kernel interfaces |
1683 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
1788 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
1684 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
1789 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
1685 | Glib::EV). |
1790 | Glib::EV). |
1686 | |
1791 | |
|
|
1792 | If you only use backends that rely on another event loop (e.g. |
|
|
1793 | "Tk"), then this module will do nothing for you. |
|
|
1794 | |
1687 | Guard |
1795 | Guard |
1688 | The guard module, when used, will be used to implement |
1796 | The guard module, when used, will be used to implement |
1689 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
1797 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
1690 | uses a lot less memory), but otherwise doesn't affect guard |
1798 | uses a lot less memory), but otherwise doesn't affect guard |
1691 | operation much. It is purely used for performance. |
1799 | operation much. It is purely used for performance. |
1692 | |
1800 | |
1693 | JSON and JSON::XS |
1801 | JSON and JSON::XS |
1694 | This module is required when you want to read or write JSON data via |
1802 | One of these modules is required when you want to read or write JSON |
1695 | AnyEvent::Handle. It is also written in pure-perl, but can take |
1803 | data via AnyEvent::Handle. JSON is also written in pure-perl, but |
1696 | advantage of the ultra-high-speed JSON::XS module when it is |
1804 | can take advantage of the ultra-high-speed JSON::XS module when it |
1697 | installed. |
1805 | is installed. |
1698 | |
|
|
1699 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1700 | installed. |
|
|
1701 | |
1806 | |
1702 | Net::SSLeay |
1807 | Net::SSLeay |
1703 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
1808 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
1704 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
1809 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
1705 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
1810 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
1706 | |
1811 | |
1707 | Time::HiRes |
1812 | Time::HiRes |
1708 | This module is part of perl since release 5.008. It will be used |
1813 | This module is part of perl since release 5.008. It will be used |
1709 | when the chosen event library does not come with a timing source on |
1814 | when the chosen event library does not come with a timing source of |
1710 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
1815 | its own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
1711 | additionally use it to try to use a monotonic clock for timing |
1816 | additionally use it to try to use a monotonic clock for timing |
1712 | stability. |
1817 | stability. |
1713 | |
1818 | |
1714 | FORK |
1819 | FORK |
1715 | Most event libraries are not fork-safe. The ones who are usually are |
1820 | Most event libraries are not fork-safe. The ones who are usually are |
1716 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1821 | because they rely on inefficient but fork-safe "select" or "poll" calls |
1717 | Only EV is fully fork-aware. |
1822 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
|
|
1823 | epoll are usually badly thought-out hacks that are incompatible with |
|
|
1824 | fork in one way or another. Only EV is fully fork-aware and ensures that |
|
|
1825 | you continue event-processing in both parent and child (or both, if you |
|
|
1826 | know what you are doing). |
|
|
1827 | |
|
|
1828 | This means that, in general, you cannot fork and do event processing in |
|
|
1829 | the child if the event library was initialised before the fork (which |
|
|
1830 | usually happens when the first AnyEvent watcher is created, or the |
|
|
1831 | library is loaded). |
1718 | |
1832 | |
1719 | If you have to fork, you must either do so *before* creating your first |
1833 | If you have to fork, you must either do so *before* creating your first |
1720 | watcher OR you must not use AnyEvent at all in the child OR you must do |
1834 | watcher OR you must not use AnyEvent at all in the child OR you must do |
1721 | something completely out of the scope of AnyEvent. |
1835 | something completely out of the scope of AnyEvent. |
|
|
1836 | |
|
|
1837 | The problem of doing event processing in the parent *and* the child is |
|
|
1838 | much more complicated: even for backends that *are* fork-aware or |
|
|
1839 | fork-safe, their behaviour is not usually what you want: fork clones all |
|
|
1840 | watchers, that means all timers, I/O watchers etc. are active in both |
|
|
1841 | parent and child, which is almost never what you want. USing "exec" to |
|
|
1842 | start worker children from some kind of manage rprocess is usually |
|
|
1843 | preferred, because it is much easier and cleaner, at the expense of |
|
|
1844 | having to have another binary. |
1722 | |
1845 | |
1723 | SECURITY CONSIDERATIONS |
1846 | SECURITY CONSIDERATIONS |
1724 | AnyEvent can be forced to load any event model via |
1847 | AnyEvent can be forced to load any event model via |
1725 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1848 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1726 | to execute arbitrary code or directly gain access, it can easily be used |
1849 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1750 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1873 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1751 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1874 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1752 | not as pronounced). |
1875 | not as pronounced). |
1753 | |
1876 | |
1754 | SEE ALSO |
1877 | SEE ALSO |
|
|
1878 | Tutorial/Introduction: AnyEvent::Intro. |
|
|
1879 | |
|
|
1880 | FAQ: AnyEvent::FAQ. |
|
|
1881 | |
1755 | Utility functions: AnyEvent::Util. |
1882 | Utility functions: AnyEvent::Util. |
1756 | |
1883 | |
1757 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1884 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1758 | Event::Lib, Qt, POE. |
1885 | Event::Lib, Qt, POE. |
1759 | |
1886 | |
1760 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1887 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1761 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1888 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1762 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
1889 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
1763 | AnyEvent::Impl::IOAsync. |
1890 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. |
1764 | |
1891 | |
1765 | Non-blocking file handles, sockets, TCP clients and servers: |
1892 | Non-blocking file handles, sockets, TCP clients and servers: |
1766 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1893 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1767 | |
1894 | |
1768 | Asynchronous DNS: AnyEvent::DNS. |
1895 | Asynchronous DNS: AnyEvent::DNS. |
1769 | |
1896 | |
1770 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1897 | Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. |
1771 | |
1898 | |
1772 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
1899 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, |
1773 | AnyEvent::HTTP. |
1900 | AnyEvent::HTTP. |
1774 | |
1901 | |
1775 | AUTHOR |
1902 | AUTHOR |
1776 | Marc Lehmann <schmorp@schmorp.de> |
1903 | Marc Lehmann <schmorp@schmorp.de> |
1777 | http://home.schmorp.de/ |
1904 | http://home.schmorp.de/ |