1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - the DBI of event loop programming |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, |
5 | 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 | # file descriptor readable |
10 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
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12 | |
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13 | # one-shot or repeating timers |
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14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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16 | |
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17 | print AnyEvent->now; # prints current event loop time |
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18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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19 | |
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20 | # POSIX signal |
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21 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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22 | |
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23 | # child process exit |
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24 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
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25 | my ($pid, $status) = @_; |
11 | ... |
26 | ... |
12 | }); |
27 | }); |
13 | |
28 | |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
29 | # called when event loop idle (if applicable) |
15 | ... |
30 | my $w = AnyEvent->idle (cb => sub { ... }); |
16 | }); |
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17 | |
31 | |
18 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
32 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
19 | $w->send; # wake up current and all future recv's |
33 | $w->send; # wake up current and all future recv's |
20 | $w->recv; # enters "main loop" till $condvar gets ->send |
34 | $w->recv; # enters "main loop" till $condvar gets ->send |
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35 | # use a condvar in callback mode: |
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36 | $w->cb (sub { $_[0]->recv }); |
21 | |
37 | |
22 | INTRODUCTION/TUTORIAL |
38 | INTRODUCTION/TUTORIAL |
23 | This manpage is mainly a reference manual. If you are interested in a |
39 | This manpage is mainly a reference manual. If you are interested in a |
24 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
25 | manpage. |
41 | manpage. |
26 | |
42 | |
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43 | SUPPORT |
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44 | There is a mailinglist for discussing all things AnyEvent, and an IRC |
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45 | channel, too. |
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46 | |
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47 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
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48 | Repository, at <http://anyevent.schmorp.de>, for more info. |
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49 | |
27 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
50 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
28 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
51 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
29 | nowadays. So what is different about AnyEvent? |
52 | nowadays. So what is different about AnyEvent? |
30 | |
53 | |
31 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
54 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
32 | policy* and AnyEvent is *small and efficient*. |
55 | policy* and AnyEvent is *small and efficient*. |
33 | |
56 | |
34 | First and foremost, *AnyEvent is not an event model* itself, it only |
57 | First and foremost, *AnyEvent is not an event model* itself, it only |
35 | interfaces to whatever event model the main program happens to use in a |
58 | interfaces to whatever event model the main program happens to use, in a |
36 | pragmatic way. For event models and certain classes of immortals alike, |
59 | pragmatic way. For event models and certain classes of immortals alike, |
37 | the statement "there can only be one" is a bitter reality: In general, |
60 | the statement "there can only be one" is a bitter reality: In general, |
38 | only one event loop can be active at the same time in a process. |
61 | only one event loop can be active at the same time in a process. |
39 | AnyEvent helps hiding the differences between those event loops. |
62 | AnyEvent cannot change this, but it can hide the differences between |
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63 | those event loops. |
40 | |
64 | |
41 | The goal of AnyEvent is to offer module authors the ability to do event |
65 | The goal of AnyEvent is to offer module authors the ability to do event |
42 | programming (waiting for I/O or timer events) without subscribing to a |
66 | programming (waiting for I/O or timer events) without subscribing to a |
43 | religion, a way of living, and most importantly: without forcing your |
67 | religion, a way of living, and most importantly: without forcing your |
44 | module users into the same thing by forcing them to use the same event |
68 | module users into the same thing by forcing them to use the same event |
45 | model you use. |
69 | model you use. |
46 | |
70 | |
47 | For modules like POE or IO::Async (which is a total misnomer as it is |
71 | For modules like POE or IO::Async (which is a total misnomer as it is |
48 | actually doing all I/O *synchronously*...), using them in your module is |
72 | actually doing all I/O *synchronously*...), using them in your module is |
49 | like joining a cult: After you joined, you are dependent on them and you |
73 | like joining a cult: After you joined, you are dependent on them and you |
50 | cannot use anything else, as it is simply incompatible to everything |
74 | cannot use anything else, as they are simply incompatible to everything |
51 | that isn't itself. What's worse, all the potential users of your module |
75 | that isn't them. What's worse, all the potential users of your module |
52 | are *also* forced to use the same event loop you use. |
76 | are *also* forced to use the same event loop you use. |
53 | |
77 | |
54 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
78 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
55 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
79 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
56 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
80 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
57 | module uses one of those, every user of your module has to use it, too. |
81 | module uses one of those, every user of your module has to use it, too. |
58 | But if your module uses AnyEvent, it works transparently with all event |
82 | But if your module uses AnyEvent, it works transparently with all event |
59 | models it supports (including stuff like POE and IO::Async, as long as |
83 | models it supports (including stuff like IO::Async, as long as those use |
60 | those use one of the supported event loops. It is trivial to add new |
84 | one of the supported event loops. It is trivial to add new event loops |
61 | event loops to AnyEvent, too, so it is future-proof). |
85 | to AnyEvent, too, so it is future-proof). |
62 | |
86 | |
63 | In addition to being free of having to use *the one and only true event |
87 | In addition to being free of having to use *the one and only true event |
64 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
88 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
65 | modules, you get an enormous amount of code and strict rules you have to |
89 | modules, you get an enormous amount of code and strict rules you have to |
66 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
90 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
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122 | These watchers are normal Perl objects with normal Perl lifetime. After |
146 | These watchers are normal Perl objects with normal Perl lifetime. After |
123 | creating a watcher it will immediately "watch" for events and invoke the |
147 | creating a watcher it will immediately "watch" for events and invoke the |
124 | callback when the event occurs (of course, only when the event model is |
148 | callback when the event occurs (of course, only when the event model is |
125 | in control). |
149 | in control). |
126 | |
150 | |
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151 | Note that callbacks must not permanently change global variables |
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152 | potentially in use by the event loop (such as $_ or $[) and that |
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153 | callbacks must not "die". The former is good programming practise in |
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154 | Perl and the latter stems from the fact that exception handling differs |
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155 | widely between event loops. |
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156 | |
127 | To disable the watcher you have to destroy it (e.g. by setting the |
157 | To disable the watcher you have to destroy it (e.g. by setting the |
128 | variable you store it in to "undef" or otherwise deleting all references |
158 | variable you store it in to "undef" or otherwise deleting all references |
129 | to it). |
159 | to it). |
130 | |
160 | |
131 | All watchers are created by calling a method on the "AnyEvent" class. |
161 | All watchers are created by calling a method on the "AnyEvent" class. |
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143 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
173 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
144 | my variables are only visible after the statement in which they are |
174 | my variables are only visible after the statement in which they are |
145 | declared. |
175 | declared. |
146 | |
176 | |
147 | I/O WATCHERS |
177 | I/O WATCHERS |
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178 | $w = AnyEvent->io ( |
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179 | fh => <filehandle_or_fileno>, |
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180 | poll => <"r" or "w">, |
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181 | cb => <callback>, |
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182 | ); |
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183 | |
148 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
184 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
149 | the following mandatory key-value pairs as arguments: |
185 | the following mandatory key-value pairs as arguments: |
150 | |
186 | |
151 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events. |
187 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
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188 | events (AnyEvent might or might not keep a reference to this file |
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189 | handle). Note that only file handles pointing to things for which |
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190 | non-blocking operation makes sense are allowed. This includes sockets, |
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191 | most character devices, pipes, fifos and so on, but not for example |
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192 | files or block devices. |
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193 | |
152 | "poll" must be a string that is either "r" or "w", which creates a |
194 | "poll" must be a string that is either "r" or "w", which creates a |
153 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
195 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
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196 | |
154 | is the callback to invoke each time the file handle becomes ready. |
197 | "cb" is the callback to invoke each time the file handle becomes ready. |
155 | |
198 | |
156 | Although the callback might get passed parameters, their value and |
199 | Although the callback might get passed parameters, their value and |
157 | presence is undefined and you cannot rely on them. Portable AnyEvent |
200 | presence is undefined and you cannot rely on them. Portable AnyEvent |
158 | callbacks cannot use arguments passed to I/O watcher callbacks. |
201 | callbacks cannot use arguments passed to I/O watcher callbacks. |
159 | |
202 | |
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163 | |
206 | |
164 | Some event loops issue spurious readyness notifications, so you should |
207 | Some event loops issue spurious readyness notifications, so you should |
165 | always use non-blocking calls when reading/writing from/to your file |
208 | always use non-blocking calls when reading/writing from/to your file |
166 | handles. |
209 | handles. |
167 | |
210 | |
168 | Example: |
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169 | |
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170 | # wait for readability of STDIN, then read a line and disable the watcher |
211 | Example: wait for readability of STDIN, then read a line and disable the |
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212 | watcher. |
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213 | |
171 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
214 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
172 | chomp (my $input = <STDIN>); |
215 | chomp (my $input = <STDIN>); |
173 | warn "read: $input\n"; |
216 | warn "read: $input\n"; |
174 | undef $w; |
217 | undef $w; |
175 | }); |
218 | }); |
176 | |
219 | |
177 | TIME WATCHERS |
220 | TIME WATCHERS |
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221 | $w = AnyEvent->timer (after => <seconds>, cb => <callback>); |
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222 | |
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223 | $w = AnyEvent->timer ( |
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224 | after => <fractional_seconds>, |
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225 | interval => <fractional_seconds>, |
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226 | cb => <callback>, |
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227 | ); |
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228 | |
178 | You can create a time watcher by calling the "AnyEvent->timer" method |
229 | You can create a time watcher by calling the "AnyEvent->timer" method |
179 | with the following mandatory arguments: |
230 | with the following mandatory arguments: |
180 | |
231 | |
181 | "after" specifies after how many seconds (fractional values are |
232 | "after" specifies after how many seconds (fractional values are |
182 | supported) the callback should be invoked. "cb" is the callback to |
233 | supported) the callback should be invoked. "cb" is the callback to |
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184 | |
235 | |
185 | Although the callback might get passed parameters, their value and |
236 | Although the callback might get passed parameters, their value and |
186 | presence is undefined and you cannot rely on them. Portable AnyEvent |
237 | presence is undefined and you cannot rely on them. Portable AnyEvent |
187 | callbacks cannot use arguments passed to time watcher callbacks. |
238 | callbacks cannot use arguments passed to time watcher callbacks. |
188 | |
239 | |
189 | The timer callback will be invoked at most once: if you want a repeating |
240 | The callback will normally be invoked once only. If you specify another |
190 | timer you have to create a new watcher (this is a limitation by both Tk |
241 | parameter, "interval", as a strictly positive number (> 0), then the |
191 | and Glib). |
242 | callback will be invoked regularly at that interval (in fractional |
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243 | seconds) after the first invocation. If "interval" is specified with a |
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244 | false value, then it is treated as if it were missing. |
192 | |
245 | |
193 | Example: |
246 | The callback will be rescheduled before invoking the callback, but no |
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247 | attempt is done to avoid timer drift in most backends, so the interval |
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248 | is only approximate. |
194 | |
249 | |
195 | # fire an event after 7.7 seconds |
250 | Example: fire an event after 7.7 seconds. |
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251 | |
196 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
252 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
197 | warn "timeout\n"; |
253 | warn "timeout\n"; |
198 | }); |
254 | }); |
199 | |
255 | |
200 | # to cancel the timer: |
256 | # to cancel the timer: |
201 | undef $w; |
257 | undef $w; |
202 | |
258 | |
203 | Example 2: |
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204 | |
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205 | # fire an event after 0.5 seconds, then roughly every second |
259 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
206 | my $w; |
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207 | |
260 | |
208 | my $cb = sub { |
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209 | # cancel the old timer while creating a new one |
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210 | $w = AnyEvent->timer (after => 1, cb => $cb); |
261 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
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262 | warn "timeout\n"; |
211 | }; |
263 | }; |
212 | |
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213 | # start the "loop" by creating the first watcher |
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214 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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215 | |
264 | |
216 | TIMING ISSUES |
265 | TIMING ISSUES |
217 | There are two ways to handle timers: based on real time (relative, "fire |
266 | There are two ways to handle timers: based on real time (relative, "fire |
218 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
267 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
219 | o'clock"). |
268 | o'clock"). |
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293 | In either case, if you care (and in most cases, you don't), then you |
342 | In either case, if you care (and in most cases, you don't), then you |
294 | can get whatever behaviour you want with any event loop, by taking |
343 | can get whatever behaviour you want with any event loop, by taking |
295 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
344 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
296 | account. |
345 | account. |
297 | |
346 | |
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347 | AnyEvent->now_update |
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348 | Some event loops (such as EV or AnyEvent::Impl::Perl) cache the |
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349 | current time for each loop iteration (see the discussion of |
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350 | AnyEvent->now, above). |
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351 | |
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352 | When a callback runs for a long time (or when the process sleeps), |
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353 | then this "current" time will differ substantially from the real |
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354 | time, which might affect timers and time-outs. |
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355 | |
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356 | When this is the case, you can call this method, which will update |
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357 | the event loop's idea of "current time". |
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358 | |
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359 | Note that updating the time *might* cause some events to be handled. |
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360 | |
298 | SIGNAL WATCHERS |
361 | SIGNAL WATCHERS |
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362 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
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363 | |
299 | You can watch for signals using a signal watcher, "signal" is the signal |
364 | You can watch for signals using a signal watcher, "signal" is the signal |
300 | *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked |
365 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
301 | whenever a signal occurs. |
366 | callback to be invoked whenever a signal occurs. |
302 | |
367 | |
303 | Although the callback might get passed parameters, their value and |
368 | Although the callback might get passed parameters, their value and |
304 | presence is undefined and you cannot rely on them. Portable AnyEvent |
369 | presence is undefined and you cannot rely on them. Portable AnyEvent |
305 | callbacks cannot use arguments passed to signal watcher callbacks. |
370 | callbacks cannot use arguments passed to signal watcher callbacks. |
306 | |
371 | |
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308 | invocation, and callback invocation will be synchronous. Synchronous |
373 | invocation, and callback invocation will be synchronous. Synchronous |
309 | means that it might take a while until the signal gets handled by the |
374 | means that it might take a while until the signal gets handled by the |
310 | process, but it is guaranteed not to interrupt any other callbacks. |
375 | process, but it is guaranteed not to interrupt any other callbacks. |
311 | |
376 | |
312 | The main advantage of using these watchers is that you can share a |
377 | The main advantage of using these watchers is that you can share a |
313 | signal between multiple watchers. |
378 | signal between multiple watchers, and AnyEvent will ensure that signals |
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379 | will not interrupt your program at bad times. |
314 | |
380 | |
315 | This watcher might use %SIG, so programs overwriting those signals |
381 | This watcher might use %SIG (depending on the event loop used), so |
316 | directly will likely not work correctly. |
382 | programs overwriting those signals directly will likely not work |
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383 | correctly. |
317 | |
384 | |
318 | Example: exit on SIGINT |
385 | Example: exit on SIGINT |
319 | |
386 | |
320 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
387 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
321 | |
388 | |
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389 | Signal Races, Delays and Workarounds |
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390 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
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391 | callbacks to signals in a generic way, which is a pity, as you cannot do |
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392 | race-free signal handling in perl, requiring C libraries for this. |
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393 | AnyEvent will try to do it's best, which means in some cases, signals |
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394 | will be delayed. The maximum time a signal might be delayed is specified |
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395 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
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396 | can be changed only before the first signal watcher is created, and |
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397 | should be left alone otherwise. This variable determines how often |
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398 | AnyEvent polls for signals (in case a wake-up was missed). Higher values |
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399 | will cause fewer spurious wake-ups, which is better for power and CPU |
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400 | saving. |
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401 | |
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402 | All these problems can be avoided by installing the optional |
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403 | Async::Interrupt module, which works with most event loops. It will not |
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404 | work with inherently broken event loops such as Event or Event::Lib (and |
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405 | not with POE currently, as POE does it's own workaround with one-second |
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406 | latency). For those, you just have to suffer the delays. |
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407 | |
322 | CHILD PROCESS WATCHERS |
408 | CHILD PROCESS WATCHERS |
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409 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
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410 | |
323 | You can also watch on a child process exit and catch its exit status. |
411 | You can also watch on a child process exit and catch its exit status. |
324 | |
412 | |
325 | The child process is specified by the "pid" argument (if set to 0, it |
413 | The child process is specified by the "pid" argument (one some backends, |
326 | watches for any child process exit). The watcher will trigger as often |
414 | using 0 watches for any child process exit, on others this will croak). |
327 | as status change for the child are received. This works by installing a |
415 | The watcher will be triggered only when the child process has finished |
328 | signal handler for "SIGCHLD". The callback will be called with the pid |
416 | and an exit status is available, not on any trace events |
329 | and exit status (as returned by waitpid), so unlike other watcher types, |
417 | (stopped/continued). |
330 | you *can* rely on child watcher callback arguments. |
418 | |
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419 | The callback will be called with the pid and exit status (as returned by |
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420 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
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421 | callback arguments. |
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422 | |
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423 | This watcher type works by installing a signal handler for "SIGCHLD", |
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424 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
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425 | random child processes (waiting for specific child processes, e.g. |
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426 | inside "system", is just fine). |
331 | |
427 | |
332 | There is a slight catch to child watchers, however: you usually start |
428 | There is a slight catch to child watchers, however: you usually start |
333 | them *after* the child process was created, and this means the process |
429 | them *after* the child process was created, and this means the process |
334 | could have exited already (and no SIGCHLD will be sent anymore). |
430 | could have exited already (and no SIGCHLD will be sent anymore). |
335 | |
431 | |
336 | Not all event models handle this correctly (POE doesn't), but even for |
432 | Not all event models handle this correctly (neither POE nor IO::Async |
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433 | do, see their AnyEvent::Impl manpages for details), but even for event |
337 | event models that *do* handle this correctly, they usually need to be |
434 | models that *do* handle this correctly, they usually need to be loaded |
338 | loaded before the process exits (i.e. before you fork in the first |
435 | before the process exits (i.e. before you fork in the first place). |
339 | place). |
436 | AnyEvent's pure perl event loop handles all cases correctly regardless |
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437 | of when you start the watcher. |
340 | |
438 | |
341 | This means you cannot create a child watcher as the very first thing in |
439 | This means you cannot create a child watcher as the very first thing in |
342 | an AnyEvent program, you *have* to create at least one watcher before |
440 | an AnyEvent program, you *have* to create at least one watcher before |
343 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
441 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
344 | |
442 | |
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443 | As most event loops do not support waiting for child events, they will |
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444 | be emulated by AnyEvent in most cases, in which the latency and race |
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445 | problems mentioned in the description of signal watchers apply. |
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446 | |
345 | Example: fork a process and wait for it |
447 | Example: fork a process and wait for it |
346 | |
448 | |
347 | my $done = AnyEvent->condvar; |
449 | my $done = AnyEvent->condvar; |
348 | |
450 | |
349 | my $pid = fork or exit 5; |
451 | my $pid = fork or exit 5; |
350 | |
452 | |
351 | my $w = AnyEvent->child ( |
453 | my $w = AnyEvent->child ( |
352 | pid => $pid, |
454 | pid => $pid, |
353 | cb => sub { |
455 | cb => sub { |
354 | my ($pid, $status) = @_; |
456 | my ($pid, $status) = @_; |
355 | warn "pid $pid exited with status $status"; |
457 | warn "pid $pid exited with status $status"; |
356 | $done->send; |
458 | $done->send; |
357 | }, |
459 | }, |
358 | ); |
460 | ); |
359 | |
461 | |
360 | # do something else, then wait for process exit |
462 | # do something else, then wait for process exit |
361 | $done->recv; |
463 | $done->recv; |
362 | |
464 | |
|
|
465 | IDLE WATCHERS |
|
|
466 | $w = AnyEvent->idle (cb => <callback>); |
|
|
467 | |
|
|
468 | Sometimes there is a need to do something, but it is not so important to |
|
|
469 | do it instantly, but only when there is nothing better to do. This |
|
|
470 | "nothing better to do" is usually defined to be "no other events need |
|
|
471 | attention by the event loop". |
|
|
472 | |
|
|
473 | Idle watchers ideally get invoked when the event loop has nothing better |
|
|
474 | to do, just before it would block the process to wait for new events. |
|
|
475 | Instead of blocking, the idle watcher is invoked. |
|
|
476 | |
|
|
477 | Most event loops unfortunately do not really support idle watchers (only |
|
|
478 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
|
|
479 | will simply call the callback "from time to time". |
|
|
480 | |
|
|
481 | Example: read lines from STDIN, but only process them when the program |
|
|
482 | is otherwise idle: |
|
|
483 | |
|
|
484 | my @lines; # read data |
|
|
485 | my $idle_w; |
|
|
486 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
|
|
487 | push @lines, scalar <STDIN>; |
|
|
488 | |
|
|
489 | # start an idle watcher, if not already done |
|
|
490 | $idle_w ||= AnyEvent->idle (cb => sub { |
|
|
491 | # handle only one line, when there are lines left |
|
|
492 | if (my $line = shift @lines) { |
|
|
493 | print "handled when idle: $line"; |
|
|
494 | } else { |
|
|
495 | # otherwise disable the idle watcher again |
|
|
496 | undef $idle_w; |
|
|
497 | } |
|
|
498 | }); |
|
|
499 | }); |
|
|
500 | |
363 | CONDITION VARIABLES |
501 | CONDITION VARIABLES |
|
|
502 | $cv = AnyEvent->condvar; |
|
|
503 | |
|
|
504 | $cv->send (<list>); |
|
|
505 | my @res = $cv->recv; |
|
|
506 | |
364 | If you are familiar with some event loops you will know that all of them |
507 | If you are familiar with some event loops you will know that all of them |
365 | require you to run some blocking "loop", "run" or similar function that |
508 | require you to run some blocking "loop", "run" or similar function that |
366 | will actively watch for new events and call your callbacks. |
509 | will actively watch for new events and call your callbacks. |
367 | |
510 | |
368 | AnyEvent is different, it expects somebody else to run the event loop |
511 | AnyEvent is slightly different: it expects somebody else to run the |
369 | and will only block when necessary (usually when told by the user). |
512 | event loop and will only block when necessary (usually when told by the |
|
|
513 | user). |
370 | |
514 | |
371 | The instrument to do that is called a "condition variable", so called |
515 | The instrument to do that is called a "condition variable", so called |
372 | because they represent a condition that must become true. |
516 | because they represent a condition that must become true. |
|
|
517 | |
|
|
518 | Now is probably a good time to look at the examples further below. |
373 | |
519 | |
374 | Condition variables can be created by calling the "AnyEvent->condvar" |
520 | Condition variables can be created by calling the "AnyEvent->condvar" |
375 | method, usually without arguments. The only argument pair allowed is |
521 | method, usually without arguments. The only argument pair allowed is |
376 | "cb", which specifies a callback to be called when the condition |
522 | "cb", which specifies a callback to be called when the condition |
377 | variable becomes true. |
523 | variable becomes true, with the condition variable as the first argument |
|
|
524 | (but not the results). |
378 | |
525 | |
379 | After creation, the condition variable is "false" until it becomes |
526 | After creation, the condition variable is "false" until it becomes |
380 | "true" by calling the "send" method (or calling the condition variable |
527 | "true" by calling the "send" method (or calling the condition variable |
381 | as if it were a callback, read about the caveats in the description for |
528 | as if it were a callback, read about the caveats in the description for |
382 | the "->send" method). |
529 | the "->send" method). |
… | |
… | |
384 | Condition variables are similar to callbacks, except that you can |
531 | Condition variables are similar to callbacks, except that you can |
385 | optionally wait for them. They can also be called merge points - points |
532 | optionally wait for them. They can also be called merge points - points |
386 | in time where multiple outstanding events have been processed. And yet |
533 | in time where multiple outstanding events have been processed. And yet |
387 | another way to call them is transactions - each condition variable can |
534 | another way to call them is transactions - each condition variable can |
388 | be used to represent a transaction, which finishes at some point and |
535 | be used to represent a transaction, which finishes at some point and |
389 | delivers a result. |
536 | delivers a result. And yet some people know them as "futures" - a |
|
|
537 | promise to compute/deliver something that you can wait for. |
390 | |
538 | |
391 | Condition variables are very useful to signal that something has |
539 | Condition variables are very useful to signal that something has |
392 | finished, for example, if you write a module that does asynchronous http |
540 | finished, for example, if you write a module that does asynchronous http |
393 | requests, then a condition variable would be the ideal candidate to |
541 | requests, then a condition variable would be the ideal candidate to |
394 | signal the availability of results. The user can either act when the |
542 | signal the availability of results. The user can either act when the |
… | |
… | |
428 | after => 1, |
576 | after => 1, |
429 | cb => sub { $result_ready->send }, |
577 | cb => sub { $result_ready->send }, |
430 | ); |
578 | ); |
431 | |
579 | |
432 | # this "blocks" (while handling events) till the callback |
580 | # this "blocks" (while handling events) till the callback |
433 | # calls send |
581 | # calls ->send |
434 | $result_ready->recv; |
582 | $result_ready->recv; |
435 | |
583 | |
436 | Example: wait for a timer, but take advantage of the fact that condition |
584 | Example: wait for a timer, but take advantage of the fact that condition |
437 | variables are also code references. |
585 | variables are also callable directly. |
438 | |
586 | |
439 | my $done = AnyEvent->condvar; |
587 | my $done = AnyEvent->condvar; |
440 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
588 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
441 | $done->recv; |
589 | $done->recv; |
|
|
590 | |
|
|
591 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
592 | callbacks. This is how you make a synchronous call, for example from the |
|
|
593 | main program: |
|
|
594 | |
|
|
595 | use AnyEvent::CouchDB; |
|
|
596 | |
|
|
597 | ... |
|
|
598 | |
|
|
599 | my @info = $couchdb->info->recv; |
|
|
600 | |
|
|
601 | And this is how you would just set a callback to be called whenever the |
|
|
602 | results are available: |
|
|
603 | |
|
|
604 | $couchdb->info->cb (sub { |
|
|
605 | my @info = $_[0]->recv; |
|
|
606 | }); |
442 | |
607 | |
443 | METHODS FOR PRODUCERS |
608 | METHODS FOR PRODUCERS |
444 | These methods should only be used by the producing side, i.e. the |
609 | These methods should only be used by the producing side, i.e. the |
445 | code/module that eventually sends the signal. Note that it is also the |
610 | code/module that eventually sends the signal. Note that it is also the |
446 | producer side which creates the condvar in most cases, but it isn't |
611 | producer side which creates the condvar in most cases, but it isn't |
… | |
… | |
456 | |
621 | |
457 | Any arguments passed to the "send" call will be returned by all |
622 | Any arguments passed to the "send" call will be returned by all |
458 | future "->recv" calls. |
623 | future "->recv" calls. |
459 | |
624 | |
460 | Condition variables are overloaded so one can call them directly (as |
625 | Condition variables are overloaded so one can call them directly (as |
461 | a code reference). Calling them directly is the same as calling |
626 | if they were a code reference). Calling them directly is the same as |
462 | "send". Note, however, that many C-based event loops do not handle |
627 | calling "send". |
463 | overloading, so as tempting as it may be, passing a condition |
|
|
464 | variable instead of a callback does not work. Both the pure perl and |
|
|
465 | EV loops support overloading, however, as well as all functions that |
|
|
466 | use perl to invoke a callback (as in AnyEvent::Socket and |
|
|
467 | AnyEvent::DNS for example). |
|
|
468 | |
628 | |
469 | $cv->croak ($error) |
629 | $cv->croak ($error) |
470 | Similar to send, but causes all call's to "->recv" to invoke |
630 | Similar to send, but causes all call's to "->recv" to invoke |
471 | "Carp::croak" with the given error message/object/scalar. |
631 | "Carp::croak" with the given error message/object/scalar. |
472 | |
632 | |
473 | This can be used to signal any errors to the condition variable |
633 | This can be used to signal any errors to the condition variable |
474 | user/consumer. |
634 | user/consumer. Doing it this way instead of calling "croak" directly |
|
|
635 | delays the error detetcion, but has the overwhelmign advantage that |
|
|
636 | it diagnoses the error at the place where the result is expected, |
|
|
637 | and not deep in some event clalback without connection to the actual |
|
|
638 | code causing the problem. |
475 | |
639 | |
476 | $cv->begin ([group callback]) |
640 | $cv->begin ([group callback]) |
477 | $cv->end |
641 | $cv->end |
478 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
479 | |
|
|
480 | These two methods can be used to combine many transactions/events |
642 | These two methods can be used to combine many transactions/events |
481 | into one. For example, a function that pings many hosts in parallel |
643 | into one. For example, a function that pings many hosts in parallel |
482 | might want to use a condition variable for the whole process. |
644 | might want to use a condition variable for the whole process. |
483 | |
645 | |
484 | Every call to "->begin" will increment a counter, and every call to |
646 | Every call to "->begin" will increment a counter, and every call to |
485 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
647 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
486 | (last) callback passed to "begin" will be executed. That callback is |
648 | (last) callback passed to "begin" will be executed, passing the |
487 | *supposed* to call "->send", but that is not required. If no |
649 | condvar as first argument. That callback is *supposed* to call |
|
|
650 | "->send", but that is not required. If no group callback was set, |
488 | callback was set, "send" will be called without any arguments. |
651 | "send" will be called without any arguments. |
489 | |
652 | |
490 | Let's clarify this with the ping example: |
653 | You can think of "$cv->send" giving you an OR condition (one call |
|
|
654 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
|
|
655 | condition (all "begin" calls must be "end"'ed before the condvar |
|
|
656 | sends). |
|
|
657 | |
|
|
658 | Let's start with a simple example: you have two I/O watchers (for |
|
|
659 | example, STDOUT and STDERR for a program), and you want to wait for |
|
|
660 | both streams to close before activating a condvar: |
491 | |
661 | |
492 | my $cv = AnyEvent->condvar; |
662 | my $cv = AnyEvent->condvar; |
493 | |
663 | |
|
|
664 | $cv->begin; # first watcher |
|
|
665 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
|
|
666 | defined sysread $fh1, my $buf, 4096 |
|
|
667 | or $cv->end; |
|
|
668 | }); |
|
|
669 | |
|
|
670 | $cv->begin; # second watcher |
|
|
671 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
|
|
672 | defined sysread $fh2, my $buf, 4096 |
|
|
673 | or $cv->end; |
|
|
674 | }); |
|
|
675 | |
|
|
676 | $cv->recv; |
|
|
677 | |
|
|
678 | This works because for every event source (EOF on file handle), |
|
|
679 | there is one call to "begin", so the condvar waits for all calls to |
|
|
680 | "end" before sending. |
|
|
681 | |
|
|
682 | The ping example mentioned above is slightly more complicated, as |
|
|
683 | the there are results to be passwd back, and the number of tasks |
|
|
684 | that are begung can potentially be zero: |
|
|
685 | |
|
|
686 | my $cv = AnyEvent->condvar; |
|
|
687 | |
494 | my %result; |
688 | my %result; |
495 | $cv->begin (sub { $cv->send (\%result) }); |
689 | $cv->begin (sub { shift->send (\%result) }); |
496 | |
690 | |
497 | for my $host (@list_of_hosts) { |
691 | for my $host (@list_of_hosts) { |
498 | $cv->begin; |
692 | $cv->begin; |
499 | ping_host_then_call_callback $host, sub { |
693 | ping_host_then_call_callback $host, sub { |
500 | $result{$host} = ...; |
694 | $result{$host} = ...; |
… | |
… | |
515 | the loop, which serves two important purposes: first, it sets the |
709 | the loop, which serves two important purposes: first, it sets the |
516 | callback to be called once the counter reaches 0, and second, it |
710 | callback to be called once the counter reaches 0, and second, it |
517 | ensures that "send" is called even when "no" hosts are being pinged |
711 | ensures that "send" is called even when "no" hosts are being pinged |
518 | (the loop doesn't execute once). |
712 | (the loop doesn't execute once). |
519 | |
713 | |
520 | This is the general pattern when you "fan out" into multiple |
714 | This is the general pattern when you "fan out" into multiple (but |
521 | subrequests: use an outer "begin"/"end" pair to set the callback and |
715 | potentially none) subrequests: use an outer "begin"/"end" pair to |
522 | ensure "end" is called at least once, and then, for each subrequest |
716 | set the callback and ensure "end" is called at least once, and then, |
523 | you start, call "begin" and for each subrequest you finish, call |
717 | for each subrequest you start, call "begin" and for each subrequest |
524 | "end". |
718 | you finish, call "end". |
525 | |
719 | |
526 | METHODS FOR CONSUMERS |
720 | METHODS FOR CONSUMERS |
527 | These methods should only be used by the consuming side, i.e. the code |
721 | These methods should only be used by the consuming side, i.e. the code |
528 | awaits the condition. |
722 | awaits the condition. |
529 | |
723 | |
… | |
… | |
538 | function will call "croak". |
732 | function will call "croak". |
539 | |
733 | |
540 | In list context, all parameters passed to "send" will be returned, |
734 | In list context, all parameters passed to "send" will be returned, |
541 | in scalar context only the first one will be returned. |
735 | in scalar context only the first one will be returned. |
542 | |
736 | |
|
|
737 | Note that doing a blocking wait in a callback is not supported by |
|
|
738 | any event loop, that is, recursive invocation of a blocking "->recv" |
|
|
739 | is not allowed, and the "recv" call will "croak" if such a condition |
|
|
740 | is detected. This condition can be slightly loosened by using |
|
|
741 | Coro::AnyEvent, which allows you to do a blocking "->recv" from any |
|
|
742 | thread that doesn't run the event loop itself. |
|
|
743 | |
543 | Not all event models support a blocking wait - some die in that case |
744 | Not all event models support a blocking wait - some die in that case |
544 | (programs might want to do that to stay interactive), so *if you are |
745 | (programs might want to do that to stay interactive), so *if you are |
545 | using this from a module, never require a blocking wait*, but let |
746 | using this from a module, never require a blocking wait*. Instead, |
546 | the caller decide whether the call will block or not (for example, |
747 | let the caller decide whether the call will block or not (for |
547 | by coupling condition variables with some kind of request results |
748 | example, by coupling condition variables with some kind of request |
548 | and supporting callbacks so the caller knows that getting the result |
749 | results and supporting callbacks so the caller knows that getting |
549 | will not block, while still supporting blocking waits if the caller |
750 | the result will not block, while still supporting blocking waits if |
550 | so desires). |
751 | the caller so desires). |
551 | |
|
|
552 | Another reason *never* to "->recv" in a module is that you cannot |
|
|
553 | sensibly have two "->recv"'s in parallel, as that would require |
|
|
554 | multiple interpreters or coroutines/threads, none of which |
|
|
555 | "AnyEvent" can supply. |
|
|
556 | |
|
|
557 | The Coro module, however, *can* and *does* supply coroutines and, in |
|
|
558 | fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe |
|
|
559 | versions and also integrates coroutines into AnyEvent, making |
|
|
560 | blocking "->recv" calls perfectly safe as long as they are done from |
|
|
561 | another coroutine (one that doesn't run the event loop). |
|
|
562 | |
752 | |
563 | You can ensure that "-recv" never blocks by setting a callback and |
753 | You can ensure that "-recv" never blocks by setting a callback and |
564 | only calling "->recv" from within that callback (or at a later |
754 | only calling "->recv" from within that callback (or at a later |
565 | time). This will work even when the event loop does not support |
755 | time). This will work even when the event loop does not support |
566 | blocking waits otherwise. |
756 | blocking waits otherwise. |
567 | |
757 | |
568 | $bool = $cv->ready |
758 | $bool = $cv->ready |
569 | Returns true when the condition is "true", i.e. whether "send" or |
759 | Returns true when the condition is "true", i.e. whether "send" or |
570 | "croak" have been called. |
760 | "croak" have been called. |
571 | |
761 | |
572 | $cb = $cv->cb ([new callback]) |
762 | $cb = $cv->cb ($cb->($cv)) |
573 | This is a mutator function that returns the callback set and |
763 | This is a mutator function that returns the callback set and |
574 | optionally replaces it before doing so. |
764 | optionally replaces it before doing so. |
575 | |
765 | |
576 | The callback will be called when the condition becomes "true", i.e. |
766 | The callback will be called when the condition becomes (or already |
577 | when "send" or "croak" are called, with the only argument being the |
767 | was) "true", i.e. when "send" or "croak" are called (or were |
578 | condition variable itself. Calling "recv" inside the callback or at |
768 | called), with the only argument being the condition variable itself. |
|
|
769 | Calling "recv" inside the callback or at any later time is |
579 | any later time is guaranteed not to block. |
770 | guaranteed not to block. |
|
|
771 | |
|
|
772 | SUPPORTED EVENT LOOPS/BACKENDS |
|
|
773 | The available backend classes are (every class has its own manpage): |
|
|
774 | |
|
|
775 | Backends that are autoprobed when no other event loop can be found. |
|
|
776 | EV is the preferred backend when no other event loop seems to be in |
|
|
777 | use. If EV is not installed, then AnyEvent will fall back to its own |
|
|
778 | pure-perl implementation, which is available everywhere as it comes |
|
|
779 | with AnyEvent itself. |
|
|
780 | |
|
|
781 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
|
|
782 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
783 | |
|
|
784 | Backends that are transparently being picked up when they are used. |
|
|
785 | These will be used when they are currently loaded when the first |
|
|
786 | watcher is created, in which case it is assumed that the application |
|
|
787 | is using them. This means that AnyEvent will automatically pick the |
|
|
788 | right backend when the main program loads an event module before |
|
|
789 | anything starts to create watchers. Nothing special needs to be done |
|
|
790 | by the main program. |
|
|
791 | |
|
|
792 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
793 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
|
|
794 | AnyEvent::Impl::Tk based on Tk, very broken. |
|
|
795 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
796 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
797 | AnyEvent::Impl::Irssi used when running within irssi. |
|
|
798 | |
|
|
799 | Backends with special needs. |
|
|
800 | Qt requires the Qt::Application to be instantiated first, but will |
|
|
801 | otherwise be picked up automatically. As long as the main program |
|
|
802 | instantiates the application before any AnyEvent watchers are |
|
|
803 | created, everything should just work. |
|
|
804 | |
|
|
805 | AnyEvent::Impl::Qt based on Qt. |
|
|
806 | |
|
|
807 | Support for IO::Async can only be partial, as it is too broken and |
|
|
808 | architecturally limited to even support the AnyEvent API. It also is |
|
|
809 | the only event loop that needs the loop to be set explicitly, so it |
|
|
810 | can only be used by a main program knowing about AnyEvent. See |
|
|
811 | AnyEvent::Impl::Async for the gory details. |
|
|
812 | |
|
|
813 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
814 | |
|
|
815 | Event loops that are indirectly supported via other backends. |
|
|
816 | Some event loops can be supported via other modules: |
|
|
817 | |
|
|
818 | There is no direct support for WxWidgets (Wx) or Prima. |
|
|
819 | |
|
|
820 | WxWidgets has no support for watching file handles. However, you can |
|
|
821 | use WxWidgets through the POE adaptor, as POE has a Wx backend that |
|
|
822 | simply polls 20 times per second, which was considered to be too |
|
|
823 | horrible to even consider for AnyEvent. |
|
|
824 | |
|
|
825 | Prima is not supported as nobody seems to be using it, but it has a |
|
|
826 | POE backend, so it can be supported through POE. |
|
|
827 | |
|
|
828 | AnyEvent knows about both Prima and Wx, however, and will try to |
|
|
829 | load POE when detecting them, in the hope that POE will pick them |
|
|
830 | up, in which case everything will be automatic. |
580 | |
831 | |
581 | GLOBAL VARIABLES AND FUNCTIONS |
832 | GLOBAL VARIABLES AND FUNCTIONS |
|
|
833 | These are not normally required to use AnyEvent, but can be useful to |
|
|
834 | write AnyEvent extension modules. |
|
|
835 | |
582 | $AnyEvent::MODEL |
836 | $AnyEvent::MODEL |
583 | Contains "undef" until the first watcher is being created. Then it |
837 | Contains "undef" until the first watcher is being created, before |
|
|
838 | the backend has been autodetected. |
|
|
839 | |
584 | contains the event model that is being used, which is the name of |
840 | Afterwards it contains the event model that is being used, which is |
585 | the Perl class implementing the model. This class is usually one of |
841 | the name of the Perl class implementing the model. This class is |
586 | the "AnyEvent::Impl:xxx" modules, but can be any other class in the |
842 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
587 | case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). |
843 | other class in the case AnyEvent has been extended at runtime (e.g. |
588 | |
844 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
589 | The known classes so far are: |
|
|
590 | |
|
|
591 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
|
|
592 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
593 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
594 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
595 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
|
|
596 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
597 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
598 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
599 | |
|
|
600 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
601 | watching file handles. However, you can use WxWidgets through the |
|
|
602 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
603 | second, which was considered to be too horrible to even consider for |
|
|
604 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by |
|
|
605 | using it's adaptor. |
|
|
606 | |
|
|
607 | AnyEvent knows about Prima and Wx and will try to use POE when |
|
|
608 | autodetecting them. |
|
|
609 | |
845 | |
610 | AnyEvent::detect |
846 | AnyEvent::detect |
611 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
847 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
612 | if necessary. You should only call this function right before you |
848 | if necessary. You should only call this function right before you |
613 | would have created an AnyEvent watcher anyway, that is, as late as |
849 | would have created an AnyEvent watcher anyway, that is, as late as |
614 | possible at runtime. |
850 | possible at runtime, and not e.g. while initialising of your module. |
|
|
851 | |
|
|
852 | If you need to do some initialisation before AnyEvent watchers are |
|
|
853 | created, use "post_detect". |
615 | |
854 | |
616 | $guard = AnyEvent::post_detect { BLOCK } |
855 | $guard = AnyEvent::post_detect { BLOCK } |
617 | Arranges for the code block to be executed as soon as the event |
856 | Arranges for the code block to be executed as soon as the event |
618 | model is autodetected (or immediately if this has already happened). |
857 | model is autodetected (or immediately if this has already happened). |
619 | |
858 | |
|
|
859 | The block will be executed *after* the actual backend has been |
|
|
860 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
|
|
861 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
|
|
862 | other initialisations - see the sources of AnyEvent::Strict or |
|
|
863 | AnyEvent::AIO to see how this is used. |
|
|
864 | |
|
|
865 | The most common usage is to create some global watchers, without |
|
|
866 | forcing event module detection too early, for example, AnyEvent::AIO |
|
|
867 | creates and installs the global IO::AIO watcher in a "post_detect" |
|
|
868 | block to avoid autodetecting the event module at load time. |
|
|
869 | |
620 | If called in scalar or list context, then it creates and returns an |
870 | If called in scalar or list context, then it creates and returns an |
621 | object that automatically removes the callback again when it is |
871 | object that automatically removes the callback again when it is |
|
|
872 | destroyed (or "undef" when the hook was immediately executed). See |
622 | destroyed. See Coro::BDB for a case where this is useful. |
873 | AnyEvent::AIO for a case where this is useful. |
|
|
874 | |
|
|
875 | Example: Create a watcher for the IO::AIO module and store it in |
|
|
876 | $WATCHER. Only do so after the event loop is initialised, though. |
|
|
877 | |
|
|
878 | our WATCHER; |
|
|
879 | |
|
|
880 | my $guard = AnyEvent::post_detect { |
|
|
881 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
|
|
882 | }; |
|
|
883 | |
|
|
884 | # the ||= is important in case post_detect immediately runs the block, |
|
|
885 | # as to not clobber the newly-created watcher. assigning both watcher and |
|
|
886 | # post_detect guard to the same variable has the advantage of users being |
|
|
887 | # able to just C<undef $WATCHER> if the watcher causes them grief. |
|
|
888 | |
|
|
889 | $WATCHER ||= $guard; |
623 | |
890 | |
624 | @AnyEvent::post_detect |
891 | @AnyEvent::post_detect |
625 | If there are any code references in this array (you can "push" to it |
892 | If there are any code references in this array (you can "push" to it |
626 | before or after loading AnyEvent), then they will called directly |
893 | before or after loading AnyEvent), then they will called directly |
627 | after the event loop has been chosen. |
894 | after the event loop has been chosen. |
628 | |
895 | |
629 | You should check $AnyEvent::MODEL before adding to this array, |
896 | You should check $AnyEvent::MODEL before adding to this array, |
630 | though: if it contains a true value then the event loop has already |
897 | though: if it is defined then the event loop has already been |
631 | been detected, and the array will be ignored. |
898 | detected, and the array will be ignored. |
632 | |
899 | |
633 | Best use "AnyEvent::post_detect { BLOCK }" instead. |
900 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
|
|
901 | allows it,as it takes care of these details. |
|
|
902 | |
|
|
903 | This variable is mainly useful for modules that can do something |
|
|
904 | useful when AnyEvent is used and thus want to know when it is |
|
|
905 | initialised, but do not need to even load it by default. This array |
|
|
906 | provides the means to hook into AnyEvent passively, without loading |
|
|
907 | it. |
634 | |
908 | |
635 | WHAT TO DO IN A MODULE |
909 | WHAT TO DO IN A MODULE |
636 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
910 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
637 | freely, but you should not load a specific event module or rely on it. |
911 | freely, but you should not load a specific event module or rely on it. |
638 | |
912 | |
… | |
… | |
689 | variable somewhere, waiting for it, and sending it when the program |
963 | variable somewhere, waiting for it, and sending it when the program |
690 | should exit cleanly. |
964 | should exit cleanly. |
691 | |
965 | |
692 | OTHER MODULES |
966 | OTHER MODULES |
693 | The following is a non-exhaustive list of additional modules that use |
967 | The following is a non-exhaustive list of additional modules that use |
694 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
968 | AnyEvent as a client and can therefore be mixed easily with other |
695 | in the same program. Some of the modules come with AnyEvent, some are |
969 | AnyEvent modules and other event loops in the same program. Some of the |
696 | available via CPAN. |
970 | modules come with AnyEvent, most are available via CPAN. |
697 | |
971 | |
698 | AnyEvent::Util |
972 | AnyEvent::Util |
699 | Contains various utility functions that replace often-used but |
973 | Contains various utility functions that replace often-used but |
700 | blocking functions such as "inet_aton" by event-/callback-based |
974 | blocking functions such as "inet_aton" by event-/callback-based |
701 | versions. |
975 | versions. |
702 | |
|
|
703 | AnyEvent::Handle |
|
|
704 | Provide read and write buffers and manages watchers for reads and |
|
|
705 | writes. |
|
|
706 | |
976 | |
707 | AnyEvent::Socket |
977 | AnyEvent::Socket |
708 | Provides various utility functions for (internet protocol) sockets, |
978 | Provides various utility functions for (internet protocol) sockets, |
709 | addresses and name resolution. Also functions to create non-blocking |
979 | addresses and name resolution. Also functions to create non-blocking |
710 | tcp connections or tcp servers, with IPv6 and SRV record support and |
980 | tcp connections or tcp servers, with IPv6 and SRV record support and |
711 | more. |
981 | more. |
712 | |
982 | |
|
|
983 | AnyEvent::Handle |
|
|
984 | Provide read and write buffers, manages watchers for reads and |
|
|
985 | writes, supports raw and formatted I/O, I/O queued and fully |
|
|
986 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
|
|
987 | |
713 | AnyEvent::DNS |
988 | AnyEvent::DNS |
714 | Provides rich asynchronous DNS resolver capabilities. |
989 | Provides rich asynchronous DNS resolver capabilities. |
715 | |
990 | |
|
|
991 | AnyEvent::HTTP |
|
|
992 | A simple-to-use HTTP library that is capable of making a lot of |
|
|
993 | concurrent HTTP requests. |
|
|
994 | |
716 | AnyEvent::HTTPD |
995 | AnyEvent::HTTPD |
717 | Provides a simple web application server framework. |
996 | Provides a simple web application server framework. |
718 | |
997 | |
719 | AnyEvent::FastPing |
998 | AnyEvent::FastPing |
720 | The fastest ping in the west. |
999 | The fastest ping in the west. |
721 | |
1000 | |
|
|
1001 | AnyEvent::DBI |
|
|
1002 | Executes DBI requests asynchronously in a proxy process. |
|
|
1003 | |
|
|
1004 | AnyEvent::AIO |
|
|
1005 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
1006 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
1007 | together. |
|
|
1008 | |
|
|
1009 | AnyEvent::BDB |
|
|
1010 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
1011 | fuses BDB and AnyEvent together. |
|
|
1012 | |
|
|
1013 | AnyEvent::GPSD |
|
|
1014 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
1015 | information. |
|
|
1016 | |
|
|
1017 | AnyEvent::IRC |
|
|
1018 | AnyEvent based IRC client module family (replacing the older |
722 | Net::IRC3 |
1019 | Net::IRC3). |
723 | AnyEvent based IRC client module family. |
|
|
724 | |
1020 | |
725 | Net::XMPP2 |
1021 | AnyEvent::XMPP |
726 | AnyEvent based XMPP (Jabber protocol) module family. |
1022 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
1023 | older Net::XMPP2>. |
|
|
1024 | |
|
|
1025 | AnyEvent::IGS |
|
|
1026 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
1027 | App::IGS). |
727 | |
1028 | |
728 | Net::FCP |
1029 | Net::FCP |
729 | AnyEvent-based implementation of the Freenet Client Protocol, |
1030 | AnyEvent-based implementation of the Freenet Client Protocol, |
730 | birthplace of AnyEvent. |
1031 | birthplace of AnyEvent. |
731 | |
1032 | |
… | |
… | |
733 | High level API for event-based execution flow control. |
1034 | High level API for event-based execution flow control. |
734 | |
1035 | |
735 | Coro |
1036 | Coro |
736 | Has special support for AnyEvent via Coro::AnyEvent. |
1037 | Has special support for AnyEvent via Coro::AnyEvent. |
737 | |
1038 | |
738 | AnyEvent::AIO, IO::AIO |
1039 | SIMPLIFIED AE API |
739 | Truly asynchronous I/O, should be in the toolbox of every event |
1040 | Starting with version 5.0, AnyEvent officially supports a second, much |
740 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
1041 | simpler, API that is designed to reduce the calling, typing and memory |
741 | together. |
1042 | overhead. |
742 | |
1043 | |
743 | AnyEvent::BDB, BDB |
1044 | See the AE manpage for details. |
744 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently |
|
|
745 | fuses IO::AIO and AnyEvent together. |
|
|
746 | |
1045 | |
747 | IO::Lambda |
1046 | ERROR AND EXCEPTION HANDLING |
748 | The lambda approach to I/O - don't ask, look there. Can use |
1047 | In general, AnyEvent does not do any error handling - it relies on the |
749 | AnyEvent. |
1048 | caller to do that if required. The AnyEvent::Strict module (see also the |
|
|
1049 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
|
|
1050 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
1051 | development. |
750 | |
1052 | |
751 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1053 | As for exception handling (i.e. runtime errors and exceptions thrown |
752 | This is an advanced topic that you do not normally need to use AnyEvent |
1054 | while executing a callback), this is not only highly event-loop |
753 | in a module. This section is only of use to event loop authors who want |
1055 | specific, but also not in any way wrapped by this module, as this is the |
754 | to provide AnyEvent compatibility. |
1056 | job of the main program. |
755 | |
1057 | |
756 | If you need to support another event library which isn't directly |
1058 | The pure perl event loop simply re-throws the exception (usually within |
757 | supported by AnyEvent, you can supply your own interface to it by |
1059 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
758 | pushing, before the first watcher gets created, the package name of the |
1060 | Glib uses "install_exception_handler" and so on. |
759 | event module and the package name of the interface to use onto |
|
|
760 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
761 | AnyEvent, so it is reasonably cheap. |
|
|
762 | |
|
|
763 | Example: |
|
|
764 | |
|
|
765 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
766 | |
|
|
767 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
768 | package/class when it finds the "urxvt" package/module is already |
|
|
769 | loaded. |
|
|
770 | |
|
|
771 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
772 | will first check for the presence of urxvt by trying to "use" the |
|
|
773 | "urxvt::anyevent" module. |
|
|
774 | |
|
|
775 | The class should provide implementations for all watcher types. See |
|
|
776 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
777 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
778 | the sources. |
|
|
779 | |
|
|
780 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
781 | provide suitable (hopefully) replacements. |
|
|
782 | |
|
|
783 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
784 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
785 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
786 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
787 | part of the *rxvt-unicode* distribution. |
|
|
788 | |
|
|
789 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
790 | condition variables: code blocking while waiting for a condition will |
|
|
791 | "die". This still works with most modules/usages, and blocking calls |
|
|
792 | must not be done in an interactive application, so it makes sense. |
|
|
793 | |
1061 | |
794 | ENVIRONMENT VARIABLES |
1062 | ENVIRONMENT VARIABLES |
795 | The following environment variables are used by this module: |
1063 | The following environment variables are used by this module or its |
|
|
1064 | submodules. |
|
|
1065 | |
|
|
1066 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1067 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1068 | enabled. |
796 | |
1069 | |
797 | "PERL_ANYEVENT_VERBOSE" |
1070 | "PERL_ANYEVENT_VERBOSE" |
798 | By default, AnyEvent will be completely silent except in fatal |
1071 | By default, AnyEvent will be completely silent except in fatal |
799 | conditions. You can set this environment variable to make AnyEvent |
1072 | conditions. You can set this environment variable to make AnyEvent |
800 | more talkative. |
1073 | more talkative. |
… | |
… | |
803 | conditions, such as not being able to load the event model specified |
1076 | conditions, such as not being able to load the event model specified |
804 | by "PERL_ANYEVENT_MODEL". |
1077 | by "PERL_ANYEVENT_MODEL". |
805 | |
1078 | |
806 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
1079 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
807 | event model it chooses. |
1080 | event model it chooses. |
|
|
1081 | |
|
|
1082 | When set to 8 or higher, then AnyEvent will report extra information |
|
|
1083 | on which optional modules it loads and how it implements certain |
|
|
1084 | features. |
|
|
1085 | |
|
|
1086 | "PERL_ANYEVENT_STRICT" |
|
|
1087 | AnyEvent does not do much argument checking by default, as thorough |
|
|
1088 | argument checking is very costly. Setting this variable to a true |
|
|
1089 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
|
|
1090 | thoroughly check the arguments passed to most method calls. If it |
|
|
1091 | finds any problems, it will croak. |
|
|
1092 | |
|
|
1093 | In other words, enables "strict" mode. |
|
|
1094 | |
|
|
1095 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
|
|
1096 | is definitely recommended to keep it off in production. Keeping |
|
|
1097 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
|
|
1098 | programs can be very useful, however. |
808 | |
1099 | |
809 | "PERL_ANYEVENT_MODEL" |
1100 | "PERL_ANYEVENT_MODEL" |
810 | This can be used to specify the event model to be used by AnyEvent, |
1101 | This can be used to specify the event model to be used by AnyEvent, |
811 | before auto detection and -probing kicks in. It must be a string |
1102 | before auto detection and -probing kicks in. It must be a string |
812 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1103 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
831 | mentioned will be used, and preference will be given to protocols |
1122 | mentioned will be used, and preference will be given to protocols |
832 | mentioned earlier in the list. |
1123 | mentioned earlier in the list. |
833 | |
1124 | |
834 | This variable can effectively be used for denial-of-service attacks |
1125 | This variable can effectively be used for denial-of-service attacks |
835 | against local programs (e.g. when setuid), although the impact is |
1126 | against local programs (e.g. when setuid), although the impact is |
836 | likely small, as the program has to handle connection errors |
1127 | likely small, as the program has to handle conenction and other |
837 | already- |
1128 | failures anyways. |
838 | |
1129 | |
839 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
1130 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
840 | IPv6, but support both and try to use both. |
1131 | IPv6, but support both and try to use both. |
841 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1132 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
842 | resolve or contact IPv6 addresses. |
1133 | resolve or contact IPv6 addresses. |
… | |
… | |
853 | EDNS0 in its DNS requests. |
1144 | EDNS0 in its DNS requests. |
854 | |
1145 | |
855 | "PERL_ANYEVENT_MAX_FORKS" |
1146 | "PERL_ANYEVENT_MAX_FORKS" |
856 | The maximum number of child processes that |
1147 | The maximum number of child processes that |
857 | "AnyEvent::Util::fork_call" will create in parallel. |
1148 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
1149 | |
|
|
1150 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
|
|
1151 | The default value for the "max_outstanding" parameter for the |
|
|
1152 | default DNS resolver - this is the maximum number of parallel DNS |
|
|
1153 | requests that are sent to the DNS server. |
|
|
1154 | |
|
|
1155 | "PERL_ANYEVENT_RESOLV_CONF" |
|
|
1156 | The file to use instead of /etc/resolv.conf (or OS-specific |
|
|
1157 | configuration) in the default resolver. When set to the empty |
|
|
1158 | string, no default config will be used. |
|
|
1159 | |
|
|
1160 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
|
|
1161 | When neither "ca_file" nor "ca_path" was specified during |
|
|
1162 | AnyEvent::TLS context creation, and either of these environment |
|
|
1163 | variables exist, they will be used to specify CA certificate |
|
|
1164 | locations instead of a system-dependent default. |
|
|
1165 | |
|
|
1166 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
|
|
1167 | When these are set to 1, then the respective modules are not loaded. |
|
|
1168 | Mostly good for testing AnyEvent itself. |
|
|
1169 | |
|
|
1170 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1171 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
1172 | in a module. This section is only of use to event loop authors who want |
|
|
1173 | to provide AnyEvent compatibility. |
|
|
1174 | |
|
|
1175 | If you need to support another event library which isn't directly |
|
|
1176 | supported by AnyEvent, you can supply your own interface to it by |
|
|
1177 | pushing, before the first watcher gets created, the package name of the |
|
|
1178 | event module and the package name of the interface to use onto |
|
|
1179 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
1180 | AnyEvent, so it is reasonably cheap. |
|
|
1181 | |
|
|
1182 | Example: |
|
|
1183 | |
|
|
1184 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
1185 | |
|
|
1186 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
1187 | package/class when it finds the "urxvt" package/module is already |
|
|
1188 | loaded. |
|
|
1189 | |
|
|
1190 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
1191 | will first check for the presence of urxvt by trying to "use" the |
|
|
1192 | "urxvt::anyevent" module. |
|
|
1193 | |
|
|
1194 | The class should provide implementations for all watcher types. See |
|
|
1195 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
1196 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
1197 | the sources. |
|
|
1198 | |
|
|
1199 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
1200 | provide suitable (hopefully) replacements. |
|
|
1201 | |
|
|
1202 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
1203 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
1204 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
1205 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
1206 | part of the *rxvt-unicode* distribution. |
|
|
1207 | |
|
|
1208 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
1209 | condition variables: code blocking while waiting for a condition will |
|
|
1210 | "die". This still works with most modules/usages, and blocking calls |
|
|
1211 | must not be done in an interactive application, so it makes sense. |
858 | |
1212 | |
859 | EXAMPLE PROGRAM |
1213 | EXAMPLE PROGRAM |
860 | The following program uses an I/O watcher to read data from STDIN, a |
1214 | The following program uses an I/O watcher to read data from STDIN, a |
861 | timer to display a message once per second, and a condition variable to |
1215 | timer to display a message once per second, and a condition variable to |
862 | quit the program when the user enters quit: |
1216 | quit the program when the user enters quit: |
… | |
… | |
1020 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1374 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1021 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1375 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1022 | which it is), lets them fire exactly once and destroys them again. |
1376 | which it is), lets them fire exactly once and destroys them again. |
1023 | |
1377 | |
1024 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1378 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1025 | distribution. |
1379 | distribution. It uses the AE interface, which makes a real difference |
|
|
1380 | for the EV and Perl backends only. |
1026 | |
1381 | |
1027 | Explanation of the columns |
1382 | Explanation of the columns |
1028 | *watcher* is the number of event watchers created/destroyed. Since |
1383 | *watcher* is the number of event watchers created/destroyed. Since |
1029 | different event models feature vastly different performances, each event |
1384 | different event models feature vastly different performances, each event |
1030 | loop was given a number of watchers so that overall runtime is |
1385 | loop was given a number of watchers so that overall runtime is |
… | |
… | |
1049 | *destroy* is the time, in microseconds, that it takes to destroy a |
1404 | *destroy* is the time, in microseconds, that it takes to destroy a |
1050 | single watcher. |
1405 | single watcher. |
1051 | |
1406 | |
1052 | Results |
1407 | Results |
1053 | name watchers bytes create invoke destroy comment |
1408 | name watchers bytes create invoke destroy comment |
1054 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1409 | EV/EV 100000 223 0.47 0.43 0.27 EV native interface |
1055 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1410 | EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers |
1056 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1411 | Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal |
1057 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1412 | Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation |
1058 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1413 | Event/Event 16000 516 31.16 31.84 0.82 Event native interface |
1059 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
1414 | Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers |
|
|
1415 | IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll |
|
|
1416 | IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll |
1060 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1417 | Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour |
1061 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1418 | Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers |
1062 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1419 | POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event |
1063 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1420 | POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select |
1064 | |
1421 | |
1065 | Discussion |
1422 | Discussion |
1066 | The benchmark does *not* measure scalability of the event loop very |
1423 | The benchmark does *not* measure scalability of the event loop very |
1067 | well. For example, a select-based event loop (such as the pure perl one) |
1424 | well. For example, a select-based event loop (such as the pure perl one) |
1068 | can never compete with an event loop that uses epoll when the number of |
1425 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1079 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1436 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1080 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
1437 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
1081 | CPU cycles with POE. |
1438 | CPU cycles with POE. |
1082 | |
1439 | |
1083 | "EV" is the sole leader regarding speed and memory use, which are both |
1440 | "EV" is the sole leader regarding speed and memory use, which are both |
1084 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
1441 | maximal/minimal, respectively. When using the AE API there is zero |
|
|
1442 | overhead (when going through the AnyEvent API create is about 5-6 times |
|
|
1443 | slower, with other times being equal, so still uses far less memory than |
1085 | far less memory than any other event loop and is still faster than Event |
1444 | any other event loop and is still faster than Event natively). |
1086 | natively. |
|
|
1087 | |
1445 | |
1088 | The pure perl implementation is hit in a few sweet spots (both the |
1446 | The pure perl implementation is hit in a few sweet spots (both the |
1089 | constant timeout and the use of a single fd hit optimisations in the |
1447 | constant timeout and the use of a single fd hit optimisations in the |
1090 | perl interpreter and the backend itself). Nevertheless this shows that |
1448 | perl interpreter and the backend itself). Nevertheless this shows that |
1091 | it adds very little overhead in itself. Like any select-based backend |
1449 | it adds very little overhead in itself. Like any select-based backend |
… | |
… | |
1093 | few of them active), of course, but this was not subject of this |
1451 | few of them active), of course, but this was not subject of this |
1094 | benchmark. |
1452 | benchmark. |
1095 | |
1453 | |
1096 | The "Event" module has a relatively high setup and callback invocation |
1454 | The "Event" module has a relatively high setup and callback invocation |
1097 | cost, but overall scores in on the third place. |
1455 | cost, but overall scores in on the third place. |
|
|
1456 | |
|
|
1457 | "IO::Async" performs admirably well, about on par with "Event", even |
|
|
1458 | when using its pure perl backend. |
1098 | |
1459 | |
1099 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1460 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1100 | callback invocation and overall ends up in the same class as "Event". |
1461 | callback invocation and overall ends up in the same class as "Event". |
1101 | However, Glib scales extremely badly, doubling the number of watchers |
1462 | However, Glib scales extremely badly, doubling the number of watchers |
1102 | increases the processing time by more than a factor of four, making it |
1463 | increases the processing time by more than a factor of four, making it |
… | |
… | |
1158 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1519 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1159 | 100 (1%) are active. This mirrors the activity of large servers with |
1520 | 100 (1%) are active. This mirrors the activity of large servers with |
1160 | many connections, most of which are idle at any one point in time. |
1521 | many connections, most of which are idle at any one point in time. |
1161 | |
1522 | |
1162 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1523 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1163 | distribution. |
1524 | distribution. It uses the AE interface, which makes a real difference |
|
|
1525 | for the EV and Perl backends only. |
1164 | |
1526 | |
1165 | Explanation of the columns |
1527 | Explanation of the columns |
1166 | *sockets* is the number of sockets, and twice the number of "servers" |
1528 | *sockets* is the number of sockets, and twice the number of "servers" |
1167 | (as each server has a read and write socket end). |
1529 | (as each server has a read and write socket end). |
1168 | |
1530 | |
… | |
… | |
1173 | single "request", that is, reading the token from the pipe and |
1535 | single "request", that is, reading the token from the pipe and |
1174 | forwarding it to another server. This includes deleting the old timeout |
1536 | forwarding it to another server. This includes deleting the old timeout |
1175 | and creating a new one that moves the timeout into the future. |
1537 | and creating a new one that moves the timeout into the future. |
1176 | |
1538 | |
1177 | Results |
1539 | Results |
1178 | name sockets create request |
1540 | name sockets create request |
1179 | EV 20000 69.01 11.16 |
1541 | EV 20000 62.66 7.99 |
1180 | Perl 20000 73.32 35.87 |
1542 | Perl 20000 68.32 32.64 |
1181 | Event 20000 212.62 257.32 |
1543 | IOAsync 20000 174.06 101.15 epoll |
1182 | Glib 20000 651.16 1896.30 |
1544 | IOAsync 20000 174.67 610.84 poll |
|
|
1545 | Event 20000 202.69 242.91 |
|
|
1546 | Glib 20000 557.01 1689.52 |
1183 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1547 | POE 20000 341.54 12086.32 uses POE::Loop::Event |
1184 | |
1548 | |
1185 | Discussion |
1549 | Discussion |
1186 | This benchmark *does* measure scalability and overall performance of the |
1550 | This benchmark *does* measure scalability and overall performance of the |
1187 | particular event loop. |
1551 | particular event loop. |
1188 | |
1552 | |
1189 | EV is again fastest. Since it is using epoll on my system, the setup |
1553 | EV is again fastest. Since it is using epoll on my system, the setup |
1190 | time is relatively high, though. |
1554 | time is relatively high, though. |
1191 | |
1555 | |
1192 | Perl surprisingly comes second. It is much faster than the C-based event |
1556 | Perl surprisingly comes second. It is much faster than the C-based event |
1193 | loops Event and Glib. |
1557 | loops Event and Glib. |
|
|
1558 | |
|
|
1559 | IO::Async performs very well when using its epoll backend, and still |
|
|
1560 | quite good compared to Glib when using its pure perl backend. |
1194 | |
1561 | |
1195 | Event suffers from high setup time as well (look at its code and you |
1562 | Event suffers from high setup time as well (look at its code and you |
1196 | will understand why). Callback invocation also has a high overhead |
1563 | will understand why). Callback invocation also has a high overhead |
1197 | compared to the "$_->() for .."-style loop that the Perl event loop |
1564 | compared to the "$_->() for .."-style loop that the Perl event loop |
1198 | uses. Event uses select or poll in basically all documented |
1565 | uses. Event uses select or poll in basically all documented |
… | |
… | |
1249 | |
1616 | |
1250 | Summary |
1617 | Summary |
1251 | * C-based event loops perform very well with small number of watchers, |
1618 | * C-based event loops perform very well with small number of watchers, |
1252 | as the management overhead dominates. |
1619 | as the management overhead dominates. |
1253 | |
1620 | |
|
|
1621 | THE IO::Lambda BENCHMARK |
|
|
1622 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
1623 | could be misinterpreted to make AnyEvent look bad. In fact, the |
|
|
1624 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
|
|
1625 | better (which shouldn't come as a surprise to anybody). As such, the |
|
|
1626 | benchmark is fine, and mostly shows that the AnyEvent backend from |
|
|
1627 | IO::Lambda isn't very optimal. But how would AnyEvent compare when used |
|
|
1628 | without the extra baggage? To explore this, I wrote the equivalent |
|
|
1629 | benchmark for AnyEvent. |
|
|
1630 | |
|
|
1631 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
1632 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
1633 | creates the next connection. This is a rather bad benchmark, as it |
|
|
1634 | doesn't test the efficiency of the framework or much non-blocking I/O, |
|
|
1635 | but it is a benchmark nevertheless. |
|
|
1636 | |
|
|
1637 | name runtime |
|
|
1638 | Lambda/select 0.330 sec |
|
|
1639 | + optimized 0.122 sec |
|
|
1640 | Lambda/AnyEvent 0.327 sec |
|
|
1641 | + optimized 0.138 sec |
|
|
1642 | Raw sockets/select 0.077 sec |
|
|
1643 | POE/select, components 0.662 sec |
|
|
1644 | POE/select, raw sockets 0.226 sec |
|
|
1645 | POE/select, optimized 0.404 sec |
|
|
1646 | |
|
|
1647 | AnyEvent/select/nb 0.085 sec |
|
|
1648 | AnyEvent/EV/nb 0.068 sec |
|
|
1649 | +state machine 0.134 sec |
|
|
1650 | |
|
|
1651 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
|
|
1652 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
1653 | defeating the purpose of an event-based solution. All of the newly |
|
|
1654 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
1655 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
1656 | resolver), so AnyEvent is at a disadvantage here, as non-blocking |
|
|
1657 | connects generally require a lot more bookkeeping and event handling |
|
|
1658 | than blocking connects (which involve a single syscall only). |
|
|
1659 | |
|
|
1660 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
|
|
1661 | offers similar expressive power as POE and IO::Lambda, using |
|
|
1662 | conventional Perl syntax. This means that both the echo server and the |
|
|
1663 | client are 100% non-blocking, further placing it at a disadvantage. |
|
|
1664 | |
|
|
1665 | As you can see, the AnyEvent + EV combination even beats the |
|
|
1666 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
|
|
1667 | backend easily beats IO::Lambda and POE. |
|
|
1668 | |
|
|
1669 | And even the 100% non-blocking version written using the high-level (and |
|
|
1670 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
|
|
1671 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
|
|
1672 | in a non-blocking way. |
|
|
1673 | |
|
|
1674 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
|
|
1675 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
|
|
1676 | part of the IO::lambda distribution and were used without any changes. |
|
|
1677 | |
|
|
1678 | SIGNALS |
|
|
1679 | AnyEvent currently installs handlers for these signals: |
|
|
1680 | |
|
|
1681 | SIGCHLD |
|
|
1682 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
|
|
1683 | emulation for event loops that do not support them natively. Also, |
|
|
1684 | some event loops install a similar handler. |
|
|
1685 | |
|
|
1686 | Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, |
|
|
1687 | then AnyEvent will reset it to default, to avoid losing child exit |
|
|
1688 | statuses. |
|
|
1689 | |
|
|
1690 | SIGPIPE |
|
|
1691 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
|
|
1692 | "undef" when AnyEvent gets loaded. |
|
|
1693 | |
|
|
1694 | The rationale for this is that AnyEvent users usually do not really |
|
|
1695 | depend on SIGPIPE delivery (which is purely an optimisation for |
|
|
1696 | shell use, or badly-written programs), but "SIGPIPE" can cause |
|
|
1697 | spurious and rare program exits as a lot of people do not expect |
|
|
1698 | "SIGPIPE" when writing to some random socket. |
|
|
1699 | |
|
|
1700 | The rationale for installing a no-op handler as opposed to ignoring |
|
|
1701 | it is that this way, the handler will be restored to defaults on |
|
|
1702 | exec. |
|
|
1703 | |
|
|
1704 | Feel free to install your own handler, or reset it to defaults. |
|
|
1705 | |
|
|
1706 | RECOMMENDED/OPTIONAL MODULES |
|
|
1707 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
|
|
1708 | it's built-in modules) are required to use it. |
|
|
1709 | |
|
|
1710 | That does not mean that AnyEvent won't take advantage of some additional |
|
|
1711 | modules if they are installed. |
|
|
1712 | |
|
|
1713 | This section epxlains which additional modules will be used, and how |
|
|
1714 | they affect AnyEvent's operetion. |
|
|
1715 | |
|
|
1716 | Async::Interrupt |
|
|
1717 | This slightly arcane module is used to implement fast signal |
|
|
1718 | handling: To my knowledge, there is no way to do completely |
|
|
1719 | race-free and quick signal handling in pure perl. To ensure that |
|
|
1720 | signals still get delivered, AnyEvent will start an interval timer |
|
|
1721 | to wake up perl (and catch the signals) with some delay (default is |
|
|
1722 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1723 | |
|
|
1724 | If this module is available, then it will be used to implement |
|
|
1725 | signal catching, which means that signals will not be delayed, and |
|
|
1726 | the event loop will not be interrupted regularly, which is more |
|
|
1727 | efficient (And good for battery life on laptops). |
|
|
1728 | |
|
|
1729 | This affects not just the pure-perl event loop, but also other event |
|
|
1730 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
|
|
1731 | |
|
|
1732 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
|
|
1733 | natively, and either employ their own workarounds (POE) or use |
|
|
1734 | AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1735 | Installing Async::Interrupt does nothing for those backends. |
|
|
1736 | |
|
|
1737 | EV This module isn't really "optional", as it is simply one of the |
|
|
1738 | backend event loops that AnyEvent can use. However, it is simply the |
|
|
1739 | best event loop available in terms of features, speed and stability: |
|
|
1740 | It supports the AnyEvent API optimally, implements all the watcher |
|
|
1741 | types in XS, does automatic timer adjustments even when no monotonic |
|
|
1742 | clock is available, can take avdantage of advanced kernel interfaces |
|
|
1743 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
|
|
1744 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
|
|
1745 | Glib::EV). |
|
|
1746 | |
|
|
1747 | Guard |
|
|
1748 | The guard module, when used, will be used to implement |
|
|
1749 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
|
|
1750 | uses a lot less memory), but otherwise doesn't affect guard |
|
|
1751 | operation much. It is purely used for performance. |
|
|
1752 | |
|
|
1753 | JSON and JSON::XS |
|
|
1754 | This module is required when you want to read or write JSON data via |
|
|
1755 | AnyEvent::Handle. It is also written in pure-perl, but can take |
|
|
1756 | advantage of the ultra-high-speed JSON::XS module when it is |
|
|
1757 | installed. |
|
|
1758 | |
|
|
1759 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1760 | installed. |
|
|
1761 | |
|
|
1762 | Net::SSLeay |
|
|
1763 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
|
|
1764 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
|
|
1765 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
|
|
1766 | |
|
|
1767 | Time::HiRes |
|
|
1768 | This module is part of perl since release 5.008. It will be used |
|
|
1769 | when the chosen event library does not come with a timing source on |
|
|
1770 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
|
|
1771 | additionally use it to try to use a monotonic clock for timing |
|
|
1772 | stability. |
|
|
1773 | |
1254 | FORK |
1774 | FORK |
1255 | Most event libraries are not fork-safe. The ones who are usually are |
1775 | Most event libraries are not fork-safe. The ones who are usually are |
1256 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1776 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1257 | Only EV is fully fork-aware. |
1777 | Only EV is fully fork-aware. |
1258 | |
1778 | |
1259 | If you have to fork, you must either do so *before* creating your first |
1779 | If you have to fork, you must either do so *before* creating your first |
1260 | watcher OR you must not use AnyEvent at all in the child. |
1780 | watcher OR you must not use AnyEvent at all in the child OR you must do |
|
|
1781 | something completely out of the scope of AnyEvent. |
1261 | |
1782 | |
1262 | SECURITY CONSIDERATIONS |
1783 | SECURITY CONSIDERATIONS |
1263 | AnyEvent can be forced to load any event model via |
1784 | AnyEvent can be forced to load any event model via |
1264 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1785 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1265 | to execute arbitrary code or directly gain access, it can easily be used |
1786 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1269 | |
1790 | |
1270 | You can make AnyEvent completely ignore this variable by deleting it |
1791 | You can make AnyEvent completely ignore this variable by deleting it |
1271 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1792 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1272 | |
1793 | |
1273 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1794 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1274 | |
1795 | |
1275 | use AnyEvent; |
1796 | use AnyEvent; |
1276 | |
1797 | |
1277 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1798 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1278 | be used to probe what backend is used and gain other information (which |
1799 | be used to probe what backend is used and gain other information (which |
1279 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
1800 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
|
|
1801 | and $ENV{PERL_ANYEVENT_STRICT}. |
|
|
1802 | |
|
|
1803 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1804 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1805 | enabled. |
|
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1806 | |
|
|
1807 | BUGS |
|
|
1808 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
|
|
1809 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
|
|
1810 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
|
|
1811 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
|
|
1812 | not as pronounced). |
1280 | |
1813 | |
1281 | SEE ALSO |
1814 | SEE ALSO |
1282 | Utility functions: AnyEvent::Util. |
1815 | Utility functions: AnyEvent::Util. |
1283 | |
1816 | |
1284 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1817 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1285 | Event::Lib, Qt, POE. |
1818 | Event::Lib, Qt, POE. |
1286 | |
1819 | |
1287 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1820 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1288 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1821 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1289 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
1822 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
|
|
1823 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. |
1290 | |
1824 | |
1291 | Non-blocking file handles, sockets, TCP clients and servers: |
1825 | Non-blocking file handles, sockets, TCP clients and servers: |
1292 | AnyEvent::Handle, AnyEvent::Socket. |
1826 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1293 | |
1827 | |
1294 | Asynchronous DNS: AnyEvent::DNS. |
1828 | Asynchronous DNS: AnyEvent::DNS. |
1295 | |
1829 | |
1296 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1830 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1297 | |
1831 | |
1298 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1832 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
|
|
1833 | AnyEvent::HTTP. |
1299 | |
1834 | |
1300 | AUTHOR |
1835 | AUTHOR |
1301 | Marc Lehmann <schmorp@schmorp.de> |
1836 | Marc Lehmann <schmorp@schmorp.de> |
1302 | http://home.schmorp.de/ |
1837 | http://home.schmorp.de/ |
1303 | |
1838 | |