1 | => NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - provide framework for multiple event loops |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
5 | loops |
5 | event loops. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
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10 | # file descriptor readable |
10 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
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12 | |
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13 | # one-shot or repeating timers |
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14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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16 | |
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17 | print AnyEvent->now; # prints current event loop time |
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18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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19 | |
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20 | # POSIX signal |
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21 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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22 | |
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23 | # child process exit |
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24 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
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25 | my ($pid, $status) = @_; |
11 | ... |
26 | ... |
12 | }); |
27 | }); |
13 | |
28 | |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
29 | # called when event loop idle (if applicable) |
15 | ... |
30 | my $w = AnyEvent->idle (cb => sub { ... }); |
16 | }); |
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17 | |
31 | |
18 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
32 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
19 | $w->send; # wake up current and all future recv's |
33 | $w->send; # wake up current and all future recv's |
20 | $w->recv; # enters "main loop" till $condvar gets ->send |
34 | $w->recv; # enters "main loop" till $condvar gets ->send |
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35 | # use a condvar in callback mode: |
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36 | $w->cb (sub { $_[0]->recv }); |
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37 | |
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38 | INTRODUCTION/TUTORIAL |
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39 | This manpage is mainly a reference manual. If you are interested in a |
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40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
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41 | manpage. |
21 | |
42 | |
22 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
43 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
23 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
44 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
24 | nowadays. So what is different about AnyEvent? |
45 | nowadays. So what is different about AnyEvent? |
25 | |
46 | |
26 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
47 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
27 | policy* and AnyEvent is *small and efficient*. |
48 | policy* and AnyEvent is *small and efficient*. |
28 | |
49 | |
29 | First and foremost, *AnyEvent is not an event model* itself, it only |
50 | First and foremost, *AnyEvent is not an event model* itself, it only |
30 | interfaces to whatever event model the main program happens to use in a |
51 | interfaces to whatever event model the main program happens to use, in a |
31 | pragmatic way. For event models and certain classes of immortals alike, |
52 | pragmatic way. For event models and certain classes of immortals alike, |
32 | the statement "there can only be one" is a bitter reality: In general, |
53 | the statement "there can only be one" is a bitter reality: In general, |
33 | only one event loop can be active at the same time in a process. |
54 | only one event loop can be active at the same time in a process. |
34 | AnyEvent helps hiding the differences between those event loops. |
55 | AnyEvent cannot change this, but it can hide the differences between |
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56 | those event loops. |
35 | |
57 | |
36 | The goal of AnyEvent is to offer module authors the ability to do event |
58 | The goal of AnyEvent is to offer module authors the ability to do event |
37 | programming (waiting for I/O or timer events) without subscribing to a |
59 | programming (waiting for I/O or timer events) without subscribing to a |
38 | religion, a way of living, and most importantly: without forcing your |
60 | religion, a way of living, and most importantly: without forcing your |
39 | module users into the same thing by forcing them to use the same event |
61 | module users into the same thing by forcing them to use the same event |
40 | model you use. |
62 | model you use. |
41 | |
63 | |
42 | For modules like POE or IO::Async (which is a total misnomer as it is |
64 | For modules like POE or IO::Async (which is a total misnomer as it is |
43 | actually doing all I/O *synchronously*...), using them in your module is |
65 | actually doing all I/O *synchronously*...), using them in your module is |
44 | like joining a cult: After you joined, you are dependent on them and you |
66 | like joining a cult: After you joined, you are dependent on them and you |
45 | cannot use anything else, as it is simply incompatible to everything |
67 | cannot use anything else, as they are simply incompatible to everything |
46 | that isn't itself. What's worse, all the potential users of your module |
68 | that isn't them. What's worse, all the potential users of your module |
47 | are *also* forced to use the same event loop you use. |
69 | are *also* forced to use the same event loop you use. |
48 | |
70 | |
49 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
71 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
50 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
72 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
51 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if your |
73 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
52 | module uses one of those, every user of your module has to use it, too. |
74 | module uses one of those, every user of your module has to use it, too. |
53 | But if your module uses AnyEvent, it works transparently with all event |
75 | But if your module uses AnyEvent, it works transparently with all event |
54 | models it supports (including stuff like POE and IO::Async, as long as |
76 | models it supports (including stuff like IO::Async, as long as those use |
55 | those use one of the supported event loops. It is trivial to add new |
77 | one of the supported event loops. It is trivial to add new event loops |
56 | event loops to AnyEvent, too, so it is future-proof). |
78 | to AnyEvent, too, so it is future-proof). |
57 | |
79 | |
58 | In addition to being free of having to use *the one and only true event |
80 | In addition to being free of having to use *the one and only true event |
59 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
81 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
60 | modules, you get an enormous amount of code and strict rules you have to |
82 | modules, you get an enormous amount of code and strict rules you have to |
61 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
83 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
62 | only offering the functionality that is necessary, in as thin as a |
84 | only offering the functionality that is necessary, in as thin as a |
63 | wrapper as technically possible. |
85 | wrapper as technically possible. |
64 | |
86 | |
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87 | Of course, AnyEvent comes with a big (and fully optional!) toolbox of |
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88 | useful functionality, such as an asynchronous DNS resolver, 100% |
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89 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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90 | such as Windows) and lots of real-world knowledge and workarounds for |
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91 | platform bugs and differences. |
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92 | |
65 | Of course, if you want lots of policy (this can arguably be somewhat |
93 | Now, if you *do want* lots of policy (this can arguably be somewhat |
66 | useful) and you want to force your users to use the one and only event |
94 | useful) and you want to force your users to use the one and only event |
67 | model, you should *not* use this module. |
95 | model, you should *not* use this module. |
68 | |
96 | |
69 | DESCRIPTION |
97 | DESCRIPTION |
70 | AnyEvent provides an identical interface to multiple event loops. This |
98 | AnyEvent provides an identical interface to multiple event loops. This |
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99 | starts using it, all bets are off. Maybe you should tell their authors |
127 | starts using it, all bets are off. Maybe you should tell their authors |
100 | to use AnyEvent so their modules work together with others seamlessly... |
128 | to use AnyEvent so their modules work together with others seamlessly... |
101 | |
129 | |
102 | The pure-perl implementation of AnyEvent is called |
130 | The pure-perl implementation of AnyEvent is called |
103 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
131 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
104 | explicitly. |
132 | explicitly and enjoy the high availability of that event loop :) |
105 | |
133 | |
106 | WATCHERS |
134 | WATCHERS |
107 | AnyEvent has the central concept of a *watcher*, which is an object that |
135 | AnyEvent has the central concept of a *watcher*, which is an object that |
108 | stores relevant data for each kind of event you are waiting for, such as |
136 | stores relevant data for each kind of event you are waiting for, such as |
109 | the callback to call, the file handle to watch, etc. |
137 | the callback to call, the file handle to watch, etc. |
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111 | These watchers are normal Perl objects with normal Perl lifetime. After |
139 | These watchers are normal Perl objects with normal Perl lifetime. After |
112 | creating a watcher it will immediately "watch" for events and invoke the |
140 | creating a watcher it will immediately "watch" for events and invoke the |
113 | callback when the event occurs (of course, only when the event model is |
141 | callback when the event occurs (of course, only when the event model is |
114 | in control). |
142 | in control). |
115 | |
143 | |
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144 | Note that callbacks must not permanently change global variables |
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145 | potentially in use by the event loop (such as $_ or $[) and that |
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146 | callbacks must not "die". The former is good programming practise in |
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147 | Perl and the latter stems from the fact that exception handling differs |
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148 | widely between event loops. |
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149 | |
116 | To disable the watcher you have to destroy it (e.g. by setting the |
150 | To disable the watcher you have to destroy it (e.g. by setting the |
117 | variable you store it in to "undef" or otherwise deleting all references |
151 | variable you store it in to "undef" or otherwise deleting all references |
118 | to it). |
152 | to it). |
119 | |
153 | |
120 | All watchers are created by calling a method on the "AnyEvent" class. |
154 | All watchers are created by calling a method on the "AnyEvent" class. |
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122 | Many watchers either are used with "recursion" (repeating timers for |
156 | Many watchers either are used with "recursion" (repeating timers for |
123 | example), or need to refer to their watcher object in other ways. |
157 | example), or need to refer to their watcher object in other ways. |
124 | |
158 | |
125 | An any way to achieve that is this pattern: |
159 | An any way to achieve that is this pattern: |
126 | |
160 | |
127 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
161 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
128 | # you can use $w here, for example to undef it |
162 | # you can use $w here, for example to undef it |
129 | undef $w; |
163 | undef $w; |
130 | }); |
164 | }); |
131 | |
165 | |
132 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
166 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
133 | my variables are only visible after the statement in which they are |
167 | my variables are only visible after the statement in which they are |
134 | declared. |
168 | declared. |
135 | |
169 | |
136 | I/O WATCHERS |
170 | I/O WATCHERS |
137 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
171 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
138 | the following mandatory key-value pairs as arguments: |
172 | the following mandatory key-value pairs as arguments: |
139 | |
173 | |
140 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events. |
174 | "fh" is the Perl *file handle* (*not* file descriptor) to watch for |
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175 | events (AnyEvent might or might not keep a reference to this file |
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176 | handle). Note that only file handles pointing to things for which |
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177 | non-blocking operation makes sense are allowed. This includes sockets, |
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178 | most character devices, pipes, fifos and so on, but not for example |
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179 | files or block devices. |
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180 | |
141 | "poll" must be a string that is either "r" or "w", which creates a |
181 | "poll" must be a string that is either "r" or "w", which creates a |
142 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
182 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
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183 | |
143 | is the callback to invoke each time the file handle becomes ready. |
184 | "cb" is the callback to invoke each time the file handle becomes ready. |
144 | |
185 | |
145 | Although the callback might get passed parameters, their value and |
186 | Although the callback might get passed parameters, their value and |
146 | presence is undefined and you cannot rely on them. Portable AnyEvent |
187 | presence is undefined and you cannot rely on them. Portable AnyEvent |
147 | callbacks cannot use arguments passed to I/O watcher callbacks. |
188 | callbacks cannot use arguments passed to I/O watcher callbacks. |
148 | |
189 | |
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152 | |
193 | |
153 | Some event loops issue spurious readyness notifications, so you should |
194 | Some event loops issue spurious readyness notifications, so you should |
154 | always use non-blocking calls when reading/writing from/to your file |
195 | always use non-blocking calls when reading/writing from/to your file |
155 | handles. |
196 | handles. |
156 | |
197 | |
157 | Example: |
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158 | |
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159 | # wait for readability of STDIN, then read a line and disable the watcher |
198 | Example: wait for readability of STDIN, then read a line and disable the |
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199 | watcher. |
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200 | |
160 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
201 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
161 | chomp (my $input = <STDIN>); |
202 | chomp (my $input = <STDIN>); |
162 | warn "read: $input\n"; |
203 | warn "read: $input\n"; |
163 | undef $w; |
204 | undef $w; |
164 | }); |
205 | }); |
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173 | |
214 | |
174 | Although the callback might get passed parameters, their value and |
215 | Although the callback might get passed parameters, their value and |
175 | presence is undefined and you cannot rely on them. Portable AnyEvent |
216 | presence is undefined and you cannot rely on them. Portable AnyEvent |
176 | callbacks cannot use arguments passed to time watcher callbacks. |
217 | callbacks cannot use arguments passed to time watcher callbacks. |
177 | |
218 | |
178 | The timer callback will be invoked at most once: if you want a repeating |
219 | The callback will normally be invoked once only. If you specify another |
179 | timer you have to create a new watcher (this is a limitation by both Tk |
220 | parameter, "interval", as a strictly positive number (> 0), then the |
180 | and Glib). |
221 | callback will be invoked regularly at that interval (in fractional |
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222 | seconds) after the first invocation. If "interval" is specified with a |
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223 | false value, then it is treated as if it were missing. |
181 | |
224 | |
182 | Example: |
225 | The callback will be rescheduled before invoking the callback, but no |
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226 | attempt is done to avoid timer drift in most backends, so the interval |
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227 | is only approximate. |
183 | |
228 | |
184 | # fire an event after 7.7 seconds |
229 | Example: fire an event after 7.7 seconds. |
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230 | |
185 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
231 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
186 | warn "timeout\n"; |
232 | warn "timeout\n"; |
187 | }); |
233 | }); |
188 | |
234 | |
189 | # to cancel the timer: |
235 | # to cancel the timer: |
190 | undef $w; |
236 | undef $w; |
191 | |
237 | |
192 | Example 2: |
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193 | |
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194 | # fire an event after 0.5 seconds, then roughly every second |
238 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
195 | my $w; |
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196 | |
239 | |
197 | my $cb = sub { |
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198 | # cancel the old timer while creating a new one |
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199 | $w = AnyEvent->timer (after => 1, cb => $cb); |
240 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
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241 | warn "timeout\n"; |
200 | }; |
242 | }; |
201 | |
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202 | # start the "loop" by creating the first watcher |
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203 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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204 | |
243 | |
205 | TIMING ISSUES |
244 | TIMING ISSUES |
206 | There are two ways to handle timers: based on real time (relative, "fire |
245 | There are two ways to handle timers: based on real time (relative, "fire |
207 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
246 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
208 | o'clock"). |
247 | o'clock"). |
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220 | on wallclock time) timers. |
259 | on wallclock time) timers. |
221 | |
260 | |
222 | AnyEvent always prefers relative timers, if available, matching the |
261 | AnyEvent always prefers relative timers, if available, matching the |
223 | AnyEvent API. |
262 | AnyEvent API. |
224 | |
263 | |
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264 | AnyEvent has two additional methods that return the "current time": |
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265 | |
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266 | AnyEvent->time |
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267 | This returns the "current wallclock time" as a fractional number of |
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268 | seconds since the Epoch (the same thing as "time" or |
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269 | "Time::HiRes::time" return, and the result is guaranteed to be |
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270 | compatible with those). |
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271 | |
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272 | It progresses independently of any event loop processing, i.e. each |
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273 | call will check the system clock, which usually gets updated |
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274 | frequently. |
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275 | |
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276 | AnyEvent->now |
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277 | This also returns the "current wallclock time", but unlike "time", |
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278 | above, this value might change only once per event loop iteration, |
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279 | depending on the event loop (most return the same time as "time", |
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280 | above). This is the time that AnyEvent's timers get scheduled |
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281 | against. |
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282 | |
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283 | *In almost all cases (in all cases if you don't care), this is the |
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284 | function to call when you want to know the current time.* |
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285 | |
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286 | This function is also often faster then "AnyEvent->time", and thus |
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287 | the preferred method if you want some timestamp (for example, |
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288 | AnyEvent::Handle uses this to update it's activity timeouts). |
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289 | |
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290 | The rest of this section is only of relevance if you try to be very |
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291 | exact with your timing, you can skip it without bad conscience. |
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292 | |
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293 | For a practical example of when these times differ, consider |
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294 | Event::Lib and EV and the following set-up: |
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295 | |
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296 | The event loop is running and has just invoked one of your callback |
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297 | at time=500 (assume no other callbacks delay processing). In your |
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298 | callback, you wait a second by executing "sleep 1" (blocking the |
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299 | process for a second) and then (at time=501) you create a relative |
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300 | timer that fires after three seconds. |
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301 | |
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302 | With Event::Lib, "AnyEvent->time" and "AnyEvent->now" will both |
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303 | return 501, because that is the current time, and the timer will be |
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304 | scheduled to fire at time=504 (501 + 3). |
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305 | |
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306 | With EV, "AnyEvent->time" returns 501 (as that is the current time), |
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307 | but "AnyEvent->now" returns 500, as that is the time the last event |
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308 | processing phase started. With EV, your timer gets scheduled to run |
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309 | at time=503 (500 + 3). |
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310 | |
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311 | In one sense, Event::Lib is more exact, as it uses the current time |
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312 | regardless of any delays introduced by event processing. However, |
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313 | most callbacks do not expect large delays in processing, so this |
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314 | causes a higher drift (and a lot more system calls to get the |
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315 | current time). |
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316 | |
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317 | In another sense, EV is more exact, as your timer will be scheduled |
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318 | at the same time, regardless of how long event processing actually |
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319 | took. |
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320 | |
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321 | In either case, if you care (and in most cases, you don't), then you |
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322 | can get whatever behaviour you want with any event loop, by taking |
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323 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
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324 | account. |
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325 | |
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326 | AnyEvent->now_update |
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327 | Some event loops (such as EV or AnyEvent::Impl::Perl) cache the |
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328 | current time for each loop iteration (see the discussion of |
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329 | AnyEvent->now, above). |
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330 | |
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331 | When a callback runs for a long time (or when the process sleeps), |
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332 | then this "current" time will differ substantially from the real |
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333 | time, which might affect timers and time-outs. |
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334 | |
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335 | When this is the case, you can call this method, which will update |
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336 | the event loop's idea of "current time". |
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337 | |
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338 | Note that updating the time *might* cause some events to be handled. |
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339 | |
225 | SIGNAL WATCHERS |
340 | SIGNAL WATCHERS |
226 | You can watch for signals using a signal watcher, "signal" is the signal |
341 | You can watch for signals using a signal watcher, "signal" is the signal |
227 | *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked |
342 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
228 | whenever a signal occurs. |
343 | callback to be invoked whenever a signal occurs. |
229 | |
344 | |
230 | Although the callback might get passed parameters, their value and |
345 | Although the callback might get passed parameters, their value and |
231 | presence is undefined and you cannot rely on them. Portable AnyEvent |
346 | presence is undefined and you cannot rely on them. Portable AnyEvent |
232 | callbacks cannot use arguments passed to signal watcher callbacks. |
347 | callbacks cannot use arguments passed to signal watcher callbacks. |
233 | |
348 | |
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248 | |
363 | |
249 | CHILD PROCESS WATCHERS |
364 | CHILD PROCESS WATCHERS |
250 | You can also watch on a child process exit and catch its exit status. |
365 | You can also watch on a child process exit and catch its exit status. |
251 | |
366 | |
252 | The child process is specified by the "pid" argument (if set to 0, it |
367 | The child process is specified by the "pid" argument (if set to 0, it |
253 | watches for any child process exit). The watcher will trigger as often |
368 | watches for any child process exit). The watcher will triggered only |
254 | as status change for the child are received. This works by installing a |
369 | when the child process has finished and an exit status is available, not |
255 | signal handler for "SIGCHLD". The callback will be called with the pid |
370 | on any trace events (stopped/continued). |
256 | and exit status (as returned by waitpid), so unlike other watcher types, |
371 | |
257 | you *can* rely on child watcher callback arguments. |
372 | The callback will be called with the pid and exit status (as returned by |
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373 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
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374 | callback arguments. |
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375 | |
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376 | This watcher type works by installing a signal handler for "SIGCHLD", |
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377 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
|
|
378 | random child processes (waiting for specific child processes, e.g. |
|
|
379 | inside "system", is just fine). |
258 | |
380 | |
259 | There is a slight catch to child watchers, however: you usually start |
381 | There is a slight catch to child watchers, however: you usually start |
260 | them *after* the child process was created, and this means the process |
382 | them *after* the child process was created, and this means the process |
261 | could have exited already (and no SIGCHLD will be sent anymore). |
383 | could have exited already (and no SIGCHLD will be sent anymore). |
262 | |
384 | |
… | |
… | |
269 | an AnyEvent program, you *have* to create at least one watcher before |
391 | an AnyEvent program, you *have* to create at least one watcher before |
270 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
392 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
271 | |
393 | |
272 | Example: fork a process and wait for it |
394 | Example: fork a process and wait for it |
273 | |
395 | |
274 | my $done = AnyEvent->condvar; |
396 | my $done = AnyEvent->condvar; |
275 | |
397 | |
276 | my $pid = fork or exit 5; |
398 | my $pid = fork or exit 5; |
277 | |
399 | |
278 | my $w = AnyEvent->child ( |
400 | my $w = AnyEvent->child ( |
279 | pid => $pid, |
401 | pid => $pid, |
280 | cb => sub { |
402 | cb => sub { |
281 | my ($pid, $status) = @_; |
403 | my ($pid, $status) = @_; |
282 | warn "pid $pid exited with status $status"; |
404 | warn "pid $pid exited with status $status"; |
283 | $done->send; |
405 | $done->send; |
284 | }, |
406 | }, |
285 | ); |
407 | ); |
286 | |
408 | |
287 | # do something else, then wait for process exit |
409 | # do something else, then wait for process exit |
288 | $done->recv; |
410 | $done->recv; |
|
|
411 | |
|
|
412 | IDLE WATCHERS |
|
|
413 | Sometimes there is a need to do something, but it is not so important to |
|
|
414 | do it instantly, but only when there is nothing better to do. This |
|
|
415 | "nothing better to do" is usually defined to be "no other events need |
|
|
416 | attention by the event loop". |
|
|
417 | |
|
|
418 | Idle watchers ideally get invoked when the event loop has nothing better |
|
|
419 | to do, just before it would block the process to wait for new events. |
|
|
420 | Instead of blocking, the idle watcher is invoked. |
|
|
421 | |
|
|
422 | Most event loops unfortunately do not really support idle watchers (only |
|
|
423 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
|
|
424 | will simply call the callback "from time to time". |
|
|
425 | |
|
|
426 | Example: read lines from STDIN, but only process them when the program |
|
|
427 | is otherwise idle: |
|
|
428 | |
|
|
429 | my @lines; # read data |
|
|
430 | my $idle_w; |
|
|
431 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
|
|
432 | push @lines, scalar <STDIN>; |
|
|
433 | |
|
|
434 | # start an idle watcher, if not already done |
|
|
435 | $idle_w ||= AnyEvent->idle (cb => sub { |
|
|
436 | # handle only one line, when there are lines left |
|
|
437 | if (my $line = shift @lines) { |
|
|
438 | print "handled when idle: $line"; |
|
|
439 | } else { |
|
|
440 | # otherwise disable the idle watcher again |
|
|
441 | undef $idle_w; |
|
|
442 | } |
|
|
443 | }); |
|
|
444 | }); |
289 | |
445 | |
290 | CONDITION VARIABLES |
446 | CONDITION VARIABLES |
291 | If you are familiar with some event loops you will know that all of them |
447 | If you are familiar with some event loops you will know that all of them |
292 | require you to run some blocking "loop", "run" or similar function that |
448 | require you to run some blocking "loop", "run" or similar function that |
293 | will actively watch for new events and call your callbacks. |
449 | will actively watch for new events and call your callbacks. |
… | |
… | |
298 | The instrument to do that is called a "condition variable", so called |
454 | The instrument to do that is called a "condition variable", so called |
299 | because they represent a condition that must become true. |
455 | because they represent a condition that must become true. |
300 | |
456 | |
301 | Condition variables can be created by calling the "AnyEvent->condvar" |
457 | Condition variables can be created by calling the "AnyEvent->condvar" |
302 | method, usually without arguments. The only argument pair allowed is |
458 | method, usually without arguments. The only argument pair allowed is |
|
|
459 | |
303 | "cb", which specifies a callback to be called when the condition |
460 | "cb", which specifies a callback to be called when the condition |
304 | variable becomes true. |
461 | variable becomes true, with the condition variable as the first argument |
|
|
462 | (but not the results). |
305 | |
463 | |
306 | After creation, the condition variable is "false" until it becomes |
464 | After creation, the condition variable is "false" until it becomes |
307 | "true" by calling the "send" method (or calling the condition variable |
465 | "true" by calling the "send" method (or calling the condition variable |
308 | as if it were a callback, read about the caveats in the description for |
466 | as if it were a callback, read about the caveats in the description for |
309 | the "->send" method). |
467 | the "->send" method). |
… | |
… | |
365 | |
523 | |
366 | my $done = AnyEvent->condvar; |
524 | my $done = AnyEvent->condvar; |
367 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
525 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
368 | $done->recv; |
526 | $done->recv; |
369 | |
527 | |
|
|
528 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
529 | callbacks. This is how you make a synchronous call, for example from the |
|
|
530 | main program: |
|
|
531 | |
|
|
532 | use AnyEvent::CouchDB; |
|
|
533 | |
|
|
534 | ... |
|
|
535 | |
|
|
536 | my @info = $couchdb->info->recv; |
|
|
537 | |
|
|
538 | And this is how you would just ste a callback to be called whenever the |
|
|
539 | results are available: |
|
|
540 | |
|
|
541 | $couchdb->info->cb (sub { |
|
|
542 | my @info = $_[0]->recv; |
|
|
543 | }); |
|
|
544 | |
370 | METHODS FOR PRODUCERS |
545 | METHODS FOR PRODUCERS |
371 | These methods should only be used by the producing side, i.e. the |
546 | These methods should only be used by the producing side, i.e. the |
372 | code/module that eventually sends the signal. Note that it is also the |
547 | code/module that eventually sends the signal. Note that it is also the |
373 | producer side which creates the condvar in most cases, but it isn't |
548 | producer side which creates the condvar in most cases, but it isn't |
374 | uncommon for the consumer to create it as well. |
549 | uncommon for the consumer to create it as well. |
… | |
… | |
494 | |
669 | |
495 | $bool = $cv->ready |
670 | $bool = $cv->ready |
496 | Returns true when the condition is "true", i.e. whether "send" or |
671 | Returns true when the condition is "true", i.e. whether "send" or |
497 | "croak" have been called. |
672 | "croak" have been called. |
498 | |
673 | |
499 | $cb = $cv->cb ([new callback]) |
674 | $cb = $cv->cb ($cb->($cv)) |
500 | This is a mutator function that returns the callback set and |
675 | This is a mutator function that returns the callback set and |
501 | optionally replaces it before doing so. |
676 | optionally replaces it before doing so. |
502 | |
677 | |
503 | The callback will be called when the condition becomes "true", i.e. |
678 | The callback will be called when the condition becomes "true", i.e. |
504 | when "send" or "croak" are called. Calling "recv" inside the |
679 | when "send" or "croak" are called, with the only argument being the |
|
|
680 | condition variable itself. Calling "recv" inside the callback or at |
505 | callback or at any later time is guaranteed not to block. |
681 | any later time is guaranteed not to block. |
506 | |
682 | |
507 | GLOBAL VARIABLES AND FUNCTIONS |
683 | GLOBAL VARIABLES AND FUNCTIONS |
508 | $AnyEvent::MODEL |
684 | $AnyEvent::MODEL |
509 | Contains "undef" until the first watcher is being created. Then it |
685 | Contains "undef" until the first watcher is being created. Then it |
510 | contains the event model that is being used, which is the name of |
686 | contains the event model that is being used, which is the name of |
… | |
… | |
624 | AnyEvent::Util |
800 | AnyEvent::Util |
625 | Contains various utility functions that replace often-used but |
801 | Contains various utility functions that replace often-used but |
626 | blocking functions such as "inet_aton" by event-/callback-based |
802 | blocking functions such as "inet_aton" by event-/callback-based |
627 | versions. |
803 | versions. |
628 | |
804 | |
629 | AnyEvent::Handle |
|
|
630 | Provide read and write buffers and manages watchers for reads and |
|
|
631 | writes. |
|
|
632 | |
|
|
633 | AnyEvent::Socket |
805 | AnyEvent::Socket |
634 | Provides various utility functions for (internet protocol) sockets, |
806 | Provides various utility functions for (internet protocol) sockets, |
635 | addresses and name resolution. Also functions to create non-blocking |
807 | addresses and name resolution. Also functions to create non-blocking |
636 | tcp connections or tcp servers, with IPv6 and SRV record support and |
808 | tcp connections or tcp servers, with IPv6 and SRV record support and |
637 | more. |
809 | more. |
638 | |
810 | |
|
|
811 | AnyEvent::Handle |
|
|
812 | Provide read and write buffers, manages watchers for reads and |
|
|
813 | writes, supports raw and formatted I/O, I/O queued and fully |
|
|
814 | transparent and non-blocking SSL/TLS. |
|
|
815 | |
639 | AnyEvent::DNS |
816 | AnyEvent::DNS |
640 | Provides rich asynchronous DNS resolver capabilities. |
817 | Provides rich asynchronous DNS resolver capabilities. |
641 | |
818 | |
|
|
819 | AnyEvent::HTTP |
|
|
820 | A simple-to-use HTTP library that is capable of making a lot of |
|
|
821 | concurrent HTTP requests. |
|
|
822 | |
642 | AnyEvent::HTTPD |
823 | AnyEvent::HTTPD |
643 | Provides a simple web application server framework. |
824 | Provides a simple web application server framework. |
644 | |
825 | |
645 | AnyEvent::FastPing |
826 | AnyEvent::FastPing |
646 | The fastest ping in the west. |
827 | The fastest ping in the west. |
647 | |
828 | |
|
|
829 | AnyEvent::DBI |
|
|
830 | Executes DBI requests asynchronously in a proxy process. |
|
|
831 | |
|
|
832 | AnyEvent::AIO |
|
|
833 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
834 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
835 | together. |
|
|
836 | |
|
|
837 | AnyEvent::BDB |
|
|
838 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
839 | fuses BDB and AnyEvent together. |
|
|
840 | |
|
|
841 | AnyEvent::GPSD |
|
|
842 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
843 | information. |
|
|
844 | |
|
|
845 | AnyEvent::IGS |
|
|
846 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
847 | App::IGS). |
|
|
848 | |
|
|
849 | AnyEvent::IRC |
|
|
850 | AnyEvent based IRC client module family (replacing the older |
648 | Net::IRC3 |
851 | Net::IRC3). |
649 | AnyEvent based IRC client module family. |
|
|
650 | |
852 | |
651 | Net::XMPP2 |
853 | Net::XMPP2 |
652 | AnyEvent based XMPP (Jabber protocol) module family. |
854 | AnyEvent based XMPP (Jabber protocol) module family. |
653 | |
855 | |
654 | Net::FCP |
856 | Net::FCP |
… | |
… | |
659 | High level API for event-based execution flow control. |
861 | High level API for event-based execution flow control. |
660 | |
862 | |
661 | Coro |
863 | Coro |
662 | Has special support for AnyEvent via Coro::AnyEvent. |
864 | Has special support for AnyEvent via Coro::AnyEvent. |
663 | |
865 | |
664 | AnyEvent::AIO, IO::AIO |
|
|
665 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
666 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
667 | together. |
|
|
668 | |
|
|
669 | AnyEvent::BDB, BDB |
|
|
670 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently |
|
|
671 | fuses IO::AIO and AnyEvent together. |
|
|
672 | |
|
|
673 | IO::Lambda |
866 | IO::Lambda |
674 | The lambda approach to I/O - don't ask, look there. Can use |
867 | The lambda approach to I/O - don't ask, look there. Can use |
675 | AnyEvent. |
868 | AnyEvent. |
676 | |
869 | |
677 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
870 | ERROR AND EXCEPTION HANDLING |
678 | This is an advanced topic that you do not normally need to use AnyEvent |
871 | In general, AnyEvent does not do any error handling - it relies on the |
679 | in a module. This section is only of use to event loop authors who want |
872 | caller to do that if required. The AnyEvent::Strict module (see also the |
680 | to provide AnyEvent compatibility. |
873 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
|
|
874 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
875 | development. |
681 | |
876 | |
682 | If you need to support another event library which isn't directly |
877 | As for exception handling (i.e. runtime errors and exceptions thrown |
683 | supported by AnyEvent, you can supply your own interface to it by |
878 | while executing a callback), this is not only highly event-loop |
684 | pushing, before the first watcher gets created, the package name of the |
879 | specific, but also not in any way wrapped by this module, as this is the |
685 | event module and the package name of the interface to use onto |
880 | job of the main program. |
686 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
687 | AnyEvent, so it is reasonably cheap. |
|
|
688 | |
881 | |
689 | Example: |
882 | The pure perl event loop simply re-throws the exception (usually within |
690 | |
883 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
691 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
884 | Glib uses "install_exception_handler" and so on. |
692 | |
|
|
693 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
694 | package/class when it finds the "urxvt" package/module is already |
|
|
695 | loaded. |
|
|
696 | |
|
|
697 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
698 | will first check for the presence of urxvt by trying to "use" the |
|
|
699 | "urxvt::anyevent" module. |
|
|
700 | |
|
|
701 | The class should provide implementations for all watcher types. See |
|
|
702 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
703 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
704 | the sources. |
|
|
705 | |
|
|
706 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
707 | provide suitable (hopefully) replacements. |
|
|
708 | |
|
|
709 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
710 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
711 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
712 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
713 | part of the *rxvt-unicode* distribution. |
|
|
714 | |
|
|
715 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
716 | condition variables: code blocking while waiting for a condition will |
|
|
717 | "die". This still works with most modules/usages, and blocking calls |
|
|
718 | must not be done in an interactive application, so it makes sense. |
|
|
719 | |
885 | |
720 | ENVIRONMENT VARIABLES |
886 | ENVIRONMENT VARIABLES |
721 | The following environment variables are used by this module: |
887 | The following environment variables are used by this module or its |
|
|
888 | submodules. |
|
|
889 | |
|
|
890 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
891 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
892 | enabled. |
722 | |
893 | |
723 | "PERL_ANYEVENT_VERBOSE" |
894 | "PERL_ANYEVENT_VERBOSE" |
724 | By default, AnyEvent will be completely silent except in fatal |
895 | By default, AnyEvent will be completely silent except in fatal |
725 | conditions. You can set this environment variable to make AnyEvent |
896 | conditions. You can set this environment variable to make AnyEvent |
726 | more talkative. |
897 | more talkative. |
… | |
… | |
729 | conditions, such as not being able to load the event model specified |
900 | conditions, such as not being able to load the event model specified |
730 | by "PERL_ANYEVENT_MODEL". |
901 | by "PERL_ANYEVENT_MODEL". |
731 | |
902 | |
732 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
903 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
733 | event model it chooses. |
904 | event model it chooses. |
|
|
905 | |
|
|
906 | "PERL_ANYEVENT_STRICT" |
|
|
907 | AnyEvent does not do much argument checking by default, as thorough |
|
|
908 | argument checking is very costly. Setting this variable to a true |
|
|
909 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
|
|
910 | thoroughly check the arguments passed to most method calls. If it |
|
|
911 | finds any problems it will croak. |
|
|
912 | |
|
|
913 | In other words, enables "strict" mode. |
|
|
914 | |
|
|
915 | Unlike "use strict", it is definitely recommended ot keep it off in |
|
|
916 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
|
|
917 | while developing programs can be very useful, however. |
734 | |
918 | |
735 | "PERL_ANYEVENT_MODEL" |
919 | "PERL_ANYEVENT_MODEL" |
736 | This can be used to specify the event model to be used by AnyEvent, |
920 | This can be used to specify the event model to be used by AnyEvent, |
737 | before auto detection and -probing kicks in. It must be a string |
921 | before auto detection and -probing kicks in. It must be a string |
738 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
922 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
743 | This functionality might change in future versions. |
927 | This functionality might change in future versions. |
744 | |
928 | |
745 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
929 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
746 | could start your program like this: |
930 | could start your program like this: |
747 | |
931 | |
748 | PERL_ANYEVENT_MODEL=Perl perl ... |
932 | PERL_ANYEVENT_MODEL=Perl perl ... |
749 | |
933 | |
750 | "PERL_ANYEVENT_PROTOCOLS" |
934 | "PERL_ANYEVENT_PROTOCOLS" |
751 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
935 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
752 | preferences for IPv4 or IPv6. The default is unspecified (and might |
936 | preferences for IPv4 or IPv6. The default is unspecified (and might |
753 | change, or be the result of auto probing). |
937 | change, or be the result of auto probing). |
… | |
… | |
757 | mentioned will be used, and preference will be given to protocols |
941 | mentioned will be used, and preference will be given to protocols |
758 | mentioned earlier in the list. |
942 | mentioned earlier in the list. |
759 | |
943 | |
760 | This variable can effectively be used for denial-of-service attacks |
944 | This variable can effectively be used for denial-of-service attacks |
761 | against local programs (e.g. when setuid), although the impact is |
945 | against local programs (e.g. when setuid), although the impact is |
762 | likely small, as the program has to handle connection errors |
946 | likely small, as the program has to handle conenction and other |
763 | already- |
947 | failures anyways. |
764 | |
948 | |
765 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
949 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
766 | IPv6, but support both and try to use both. |
950 | IPv6, but support both and try to use both. |
767 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
951 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
768 | resolve or contact IPv6 addresses. |
952 | resolve or contact IPv6 addresses. |
… | |
… | |
775 | but some (broken) firewalls drop such DNS packets, which is why it |
959 | but some (broken) firewalls drop such DNS packets, which is why it |
776 | is off by default. |
960 | is off by default. |
777 | |
961 | |
778 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
962 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
779 | EDNS0 in its DNS requests. |
963 | EDNS0 in its DNS requests. |
|
|
964 | |
|
|
965 | "PERL_ANYEVENT_MAX_FORKS" |
|
|
966 | The maximum number of child processes that |
|
|
967 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
968 | |
|
|
969 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
970 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
971 | in a module. This section is only of use to event loop authors who want |
|
|
972 | to provide AnyEvent compatibility. |
|
|
973 | |
|
|
974 | If you need to support another event library which isn't directly |
|
|
975 | supported by AnyEvent, you can supply your own interface to it by |
|
|
976 | pushing, before the first watcher gets created, the package name of the |
|
|
977 | event module and the package name of the interface to use onto |
|
|
978 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
979 | AnyEvent, so it is reasonably cheap. |
|
|
980 | |
|
|
981 | Example: |
|
|
982 | |
|
|
983 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
984 | |
|
|
985 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
986 | package/class when it finds the "urxvt" package/module is already |
|
|
987 | loaded. |
|
|
988 | |
|
|
989 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
990 | will first check for the presence of urxvt by trying to "use" the |
|
|
991 | "urxvt::anyevent" module. |
|
|
992 | |
|
|
993 | The class should provide implementations for all watcher types. See |
|
|
994 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
995 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
996 | the sources. |
|
|
997 | |
|
|
998 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
999 | provide suitable (hopefully) replacements. |
|
|
1000 | |
|
|
1001 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
1002 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
1003 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
1004 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
1005 | part of the *rxvt-unicode* distribution. |
|
|
1006 | |
|
|
1007 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
1008 | condition variables: code blocking while waiting for a condition will |
|
|
1009 | "die". This still works with most modules/usages, and blocking calls |
|
|
1010 | must not be done in an interactive application, so it makes sense. |
780 | |
1011 | |
781 | EXAMPLE PROGRAM |
1012 | EXAMPLE PROGRAM |
782 | The following program uses an I/O watcher to read data from STDIN, a |
1013 | The following program uses an I/O watcher to read data from STDIN, a |
783 | timer to display a message once per second, and a condition variable to |
1014 | timer to display a message once per second, and a condition variable to |
784 | quit the program when the user enters quit: |
1015 | quit the program when the user enters quit: |
… | |
… | |
971 | *destroy* is the time, in microseconds, that it takes to destroy a |
1202 | *destroy* is the time, in microseconds, that it takes to destroy a |
972 | single watcher. |
1203 | single watcher. |
973 | |
1204 | |
974 | Results |
1205 | Results |
975 | name watchers bytes create invoke destroy comment |
1206 | name watchers bytes create invoke destroy comment |
976 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1207 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
977 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1208 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
978 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1209 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
979 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1210 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
980 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1211 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
981 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
1212 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
982 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1213 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
983 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1214 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
984 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1215 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
985 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1216 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
986 | |
1217 | |
987 | Discussion |
1218 | Discussion |
988 | The benchmark does *not* measure scalability of the event loop very |
1219 | The benchmark does *not* measure scalability of the event loop very |
989 | well. For example, a select-based event loop (such as the pure perl one) |
1220 | well. For example, a select-based event loop (such as the pure perl one) |
990 | can never compete with an event loop that uses epoll when the number of |
1221 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1171 | |
1402 | |
1172 | Summary |
1403 | Summary |
1173 | * C-based event loops perform very well with small number of watchers, |
1404 | * C-based event loops perform very well with small number of watchers, |
1174 | as the management overhead dominates. |
1405 | as the management overhead dominates. |
1175 | |
1406 | |
|
|
1407 | THE IO::Lambda BENCHMARK |
|
|
1408 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
1409 | could be misinterpreted to make AnyEvent look bad. In fact, the |
|
|
1410 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
|
|
1411 | better (which shouldn't come as a surprise to anybody). As such, the |
|
|
1412 | benchmark is fine, and shows that the AnyEvent backend from IO::Lambda |
|
|
1413 | isn't very optimal. But how would AnyEvent compare when used without the |
|
|
1414 | extra baggage? To explore this, I wrote the equivalent benchmark for |
|
|
1415 | AnyEvent. |
|
|
1416 | |
|
|
1417 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
1418 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
1419 | creates the next connection. This is a rather bad benchmark, as it |
|
|
1420 | doesn't test the efficiency of the framework, but it is a benchmark |
|
|
1421 | nevertheless. |
|
|
1422 | |
|
|
1423 | name runtime |
|
|
1424 | Lambda/select 0.330 sec |
|
|
1425 | + optimized 0.122 sec |
|
|
1426 | Lambda/AnyEvent 0.327 sec |
|
|
1427 | + optimized 0.138 sec |
|
|
1428 | Raw sockets/select 0.077 sec |
|
|
1429 | POE/select, components 0.662 sec |
|
|
1430 | POE/select, raw sockets 0.226 sec |
|
|
1431 | POE/select, optimized 0.404 sec |
|
|
1432 | |
|
|
1433 | AnyEvent/select/nb 0.085 sec |
|
|
1434 | AnyEvent/EV/nb 0.068 sec |
|
|
1435 | +state machine 0.134 sec |
|
|
1436 | |
|
|
1437 | The benchmark is also a bit unfair (my fault) - the IO::Lambda |
|
|
1438 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
1439 | defeating the purpose of an event-based solution. All of the newly |
|
|
1440 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
1441 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
1442 | resolver), so AnyEvent is at a disadvantage here as non-blocking |
|
|
1443 | connects generally require a lot more bookkeeping and event handling |
|
|
1444 | than blocking connects (which involve a single syscall only). |
|
|
1445 | |
|
|
1446 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
|
|
1447 | offers similar expressive power as POE and IO::Lambda (using |
|
|
1448 | conventional Perl syntax), which means both the echo server and the |
|
|
1449 | client are 100% non-blocking w.r.t. I/O, further placing it at a |
|
|
1450 | disadvantage. |
|
|
1451 | |
|
|
1452 | As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets |
|
|
1453 | benchmark", while AnyEvent + its pure perl backend easily beats |
|
|
1454 | IO::Lambda and POE. |
|
|
1455 | |
|
|
1456 | And even the 100% non-blocking version written using the high-level (and |
|
|
1457 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda, even |
|
|
1458 | thought it does all of DNS, tcp-connect and socket I/O in a non-blocking |
|
|
1459 | way. |
|
|
1460 | |
|
|
1461 | The two AnyEvent benchmarks can be found as eg/ae0.pl and eg/ae2.pl in |
|
|
1462 | the AnyEvent distribution, the remaining benchmarks are part of the |
|
|
1463 | IO::lambda distribution and were used without any changes. |
|
|
1464 | |
|
|
1465 | SIGNALS |
|
|
1466 | AnyEvent currently installs handlers for these signals: |
|
|
1467 | |
|
|
1468 | SIGCHLD |
|
|
1469 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
|
|
1470 | emulation for event loops that do not support them natively. Also, |
|
|
1471 | some event loops install a similar handler. |
|
|
1472 | |
|
|
1473 | SIGPIPE |
|
|
1474 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
|
|
1475 | "undef" when AnyEvent gets loaded. |
|
|
1476 | |
|
|
1477 | The rationale for this is that AnyEvent users usually do not really |
|
|
1478 | depend on SIGPIPE delivery (which is purely an optimisation for |
|
|
1479 | shell use, or badly-written programs), but "SIGPIPE" can cause |
|
|
1480 | spurious and rare program exits as a lot of people do not expect |
|
|
1481 | "SIGPIPE" when writing to some random socket. |
|
|
1482 | |
|
|
1483 | The rationale for installing a no-op handler as opposed to ignoring |
|
|
1484 | it is that this way, the handler will be restored to defaults on |
|
|
1485 | exec. |
|
|
1486 | |
|
|
1487 | Feel free to install your own handler, or reset it to defaults. |
|
|
1488 | |
1176 | FORK |
1489 | FORK |
1177 | Most event libraries are not fork-safe. The ones who are usually are |
1490 | Most event libraries are not fork-safe. The ones who are usually are |
1178 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1491 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1179 | Only EV is fully fork-aware. |
1492 | Only EV is fully fork-aware. |
1180 | |
1493 | |
… | |
… | |
1190 | model than specified in the variable. |
1503 | model than specified in the variable. |
1191 | |
1504 | |
1192 | You can make AnyEvent completely ignore this variable by deleting it |
1505 | You can make AnyEvent completely ignore this variable by deleting it |
1193 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1506 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1194 | |
1507 | |
1195 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1508 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1196 | |
1509 | |
1197 | use AnyEvent; |
1510 | use AnyEvent; |
1198 | |
1511 | |
1199 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1512 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1200 | be used to probe what backend is used and gain other information (which |
1513 | be used to probe what backend is used and gain other information (which |
1201 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
1514 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
|
|
1515 | and $ENV{PERL_ANYEVENT_STRICT}. |
|
|
1516 | |
|
|
1517 | BUGS |
|
|
1518 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
|
|
1519 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
|
|
1520 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
|
|
1521 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
|
|
1522 | not as pronounced). |
1202 | |
1523 | |
1203 | SEE ALSO |
1524 | SEE ALSO |
1204 | Utility functions: AnyEvent::Util. |
1525 | Utility functions: AnyEvent::Util. |
1205 | |
1526 | |
1206 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1527 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
… | |
… | |
1218 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1539 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1219 | |
1540 | |
1220 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1541 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1221 | |
1542 | |
1222 | AUTHOR |
1543 | AUTHOR |
1223 | Marc Lehmann <schmorp@schmorp.de> |
1544 | Marc Lehmann <schmorp@schmorp.de> |
1224 | http://home.schmorp.de/ |
1545 | http://home.schmorp.de/ |
1225 | |
1546 | |