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* (or a naked 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 | |
263 | Not all event models handle this correctly (POE doesn't), but even for |
385 | Not all event models handle this correctly (neither POE nor IO::Async |
|
|
386 | do, see their AnyEvent::Impl manpages for details), but even for event |
264 | event models that *do* handle this correctly, they usually need to be |
387 | models that *do* handle this correctly, they usually need to be loaded |
265 | loaded before the process exits (i.e. before you fork in the first |
388 | before the process exits (i.e. before you fork in the first place). |
266 | place). |
389 | AnyEvent's pure perl event loop handles all cases correctly regardless |
|
|
390 | of when you start the watcher. |
267 | |
391 | |
268 | This means you cannot create a child watcher as the very first thing in |
392 | This means you cannot create a child watcher as the very first thing in |
269 | an AnyEvent program, you *have* to create at least one watcher before |
393 | an AnyEvent program, you *have* to create at least one watcher before |
270 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
394 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
271 | |
395 | |
272 | Example: fork a process and wait for it |
396 | Example: fork a process and wait for it |
273 | |
397 | |
274 | my $done = AnyEvent->condvar; |
398 | my $done = AnyEvent->condvar; |
275 | |
399 | |
276 | my $pid = fork or exit 5; |
400 | my $pid = fork or exit 5; |
277 | |
401 | |
278 | my $w = AnyEvent->child ( |
402 | my $w = AnyEvent->child ( |
279 | pid => $pid, |
403 | pid => $pid, |
280 | cb => sub { |
404 | cb => sub { |
281 | my ($pid, $status) = @_; |
405 | my ($pid, $status) = @_; |
282 | warn "pid $pid exited with status $status"; |
406 | warn "pid $pid exited with status $status"; |
283 | $done->send; |
407 | $done->send; |
284 | }, |
408 | }, |
285 | ); |
409 | ); |
286 | |
410 | |
287 | # do something else, then wait for process exit |
411 | # do something else, then wait for process exit |
288 | $done->recv; |
412 | $done->recv; |
|
|
413 | |
|
|
414 | IDLE WATCHERS |
|
|
415 | Sometimes there is a need to do something, but it is not so important to |
|
|
416 | do it instantly, but only when there is nothing better to do. This |
|
|
417 | "nothing better to do" is usually defined to be "no other events need |
|
|
418 | attention by the event loop". |
|
|
419 | |
|
|
420 | Idle watchers ideally get invoked when the event loop has nothing better |
|
|
421 | to do, just before it would block the process to wait for new events. |
|
|
422 | Instead of blocking, the idle watcher is invoked. |
|
|
423 | |
|
|
424 | Most event loops unfortunately do not really support idle watchers (only |
|
|
425 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
|
|
426 | will simply call the callback "from time to time". |
|
|
427 | |
|
|
428 | Example: read lines from STDIN, but only process them when the program |
|
|
429 | is otherwise idle: |
|
|
430 | |
|
|
431 | my @lines; # read data |
|
|
432 | my $idle_w; |
|
|
433 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
|
|
434 | push @lines, scalar <STDIN>; |
|
|
435 | |
|
|
436 | # start an idle watcher, if not already done |
|
|
437 | $idle_w ||= AnyEvent->idle (cb => sub { |
|
|
438 | # handle only one line, when there are lines left |
|
|
439 | if (my $line = shift @lines) { |
|
|
440 | print "handled when idle: $line"; |
|
|
441 | } else { |
|
|
442 | # otherwise disable the idle watcher again |
|
|
443 | undef $idle_w; |
|
|
444 | } |
|
|
445 | }); |
|
|
446 | }); |
289 | |
447 | |
290 | CONDITION VARIABLES |
448 | CONDITION VARIABLES |
291 | If you are familiar with some event loops you will know that all of them |
449 | 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 |
450 | require you to run some blocking "loop", "run" or similar function that |
293 | will actively watch for new events and call your callbacks. |
451 | will actively watch for new events and call your callbacks. |
… | |
… | |
298 | The instrument to do that is called a "condition variable", so called |
456 | The instrument to do that is called a "condition variable", so called |
299 | because they represent a condition that must become true. |
457 | because they represent a condition that must become true. |
300 | |
458 | |
301 | Condition variables can be created by calling the "AnyEvent->condvar" |
459 | Condition variables can be created by calling the "AnyEvent->condvar" |
302 | method, usually without arguments. The only argument pair allowed is |
460 | method, usually without arguments. The only argument pair allowed is |
|
|
461 | |
303 | "cb", which specifies a callback to be called when the condition |
462 | "cb", which specifies a callback to be called when the condition |
304 | variable becomes true. |
463 | variable becomes true, with the condition variable as the first argument |
|
|
464 | (but not the results). |
305 | |
465 | |
306 | After creation, the condition variable is "false" until it becomes |
466 | After creation, the condition variable is "false" until it becomes |
307 | "true" by calling the "send" method (or calling the condition variable |
467 | "true" by calling the "send" method (or calling the condition variable |
308 | as if it were a callback). |
468 | as if it were a callback, read about the caveats in the description for |
|
|
469 | the "->send" method). |
309 | |
470 | |
310 | Condition variables are similar to callbacks, except that you can |
471 | Condition variables are similar to callbacks, except that you can |
311 | optionally wait for them. They can also be called merge points - points |
472 | optionally wait for them. They can also be called merge points - points |
312 | in time where multiple outstanding events have been processed. And yet |
473 | in time where multiple outstanding events have been processed. And yet |
313 | another way to call them is transactions - each condition variable can |
474 | another way to call them is transactions - each condition variable can |
… | |
… | |
364 | |
525 | |
365 | my $done = AnyEvent->condvar; |
526 | my $done = AnyEvent->condvar; |
366 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
527 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
367 | $done->recv; |
528 | $done->recv; |
368 | |
529 | |
|
|
530 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
531 | callbacks. This is how you make a synchronous call, for example from the |
|
|
532 | main program: |
|
|
533 | |
|
|
534 | use AnyEvent::CouchDB; |
|
|
535 | |
|
|
536 | ... |
|
|
537 | |
|
|
538 | my @info = $couchdb->info->recv; |
|
|
539 | |
|
|
540 | And this is how you would just ste a callback to be called whenever the |
|
|
541 | results are available: |
|
|
542 | |
|
|
543 | $couchdb->info->cb (sub { |
|
|
544 | my @info = $_[0]->recv; |
|
|
545 | }); |
|
|
546 | |
369 | METHODS FOR PRODUCERS |
547 | METHODS FOR PRODUCERS |
370 | These methods should only be used by the producing side, i.e. the |
548 | These methods should only be used by the producing side, i.e. the |
371 | code/module that eventually sends the signal. Note that it is also the |
549 | code/module that eventually sends the signal. Note that it is also the |
372 | producer side which creates the condvar in most cases, but it isn't |
550 | producer side which creates the condvar in most cases, but it isn't |
373 | uncommon for the consumer to create it as well. |
551 | uncommon for the consumer to create it as well. |
… | |
… | |
383 | Any arguments passed to the "send" call will be returned by all |
561 | Any arguments passed to the "send" call will be returned by all |
384 | future "->recv" calls. |
562 | future "->recv" calls. |
385 | |
563 | |
386 | Condition variables are overloaded so one can call them directly (as |
564 | Condition variables are overloaded so one can call them directly (as |
387 | a code reference). Calling them directly is the same as calling |
565 | a code reference). Calling them directly is the same as calling |
388 | "send". |
566 | "send". Note, however, that many C-based event loops do not handle |
|
|
567 | overloading, so as tempting as it may be, passing a condition |
|
|
568 | variable instead of a callback does not work. Both the pure perl and |
|
|
569 | EV loops support overloading, however, as well as all functions that |
|
|
570 | use perl to invoke a callback (as in AnyEvent::Socket and |
|
|
571 | AnyEvent::DNS for example). |
389 | |
572 | |
390 | $cv->croak ($error) |
573 | $cv->croak ($error) |
391 | Similar to send, but causes all call's to "->recv" to invoke |
574 | Similar to send, but causes all call's to "->recv" to invoke |
392 | "Carp::croak" with the given error message/object/scalar. |
575 | "Carp::croak" with the given error message/object/scalar. |
393 | |
576 | |
394 | This can be used to signal any errors to the condition variable |
577 | This can be used to signal any errors to the condition variable |
395 | user/consumer. |
578 | user/consumer. |
396 | |
579 | |
397 | $cv->begin ([group callback]) |
580 | $cv->begin ([group callback]) |
398 | $cv->end |
581 | $cv->end |
399 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
400 | |
|
|
401 | These two methods can be used to combine many transactions/events |
582 | These two methods can be used to combine many transactions/events |
402 | into one. For example, a function that pings many hosts in parallel |
583 | into one. For example, a function that pings many hosts in parallel |
403 | might want to use a condition variable for the whole process. |
584 | might want to use a condition variable for the whole process. |
404 | |
585 | |
405 | Every call to "->begin" will increment a counter, and every call to |
586 | Every call to "->begin" will increment a counter, and every call to |
406 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
587 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
407 | (last) callback passed to "begin" will be executed. That callback is |
588 | (last) callback passed to "begin" will be executed. That callback is |
408 | *supposed* to call "->send", but that is not required. If no |
589 | *supposed* to call "->send", but that is not required. If no |
409 | callback was set, "send" will be called without any arguments. |
590 | callback was set, "send" will be called without any arguments. |
410 | |
591 | |
411 | Let's clarify this with the ping example: |
592 | You can think of "$cv->send" giving you an OR condition (one call |
|
|
593 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
|
|
594 | condition (all "begin" calls must be "end"'ed before the condvar |
|
|
595 | sends). |
|
|
596 | |
|
|
597 | Let's start with a simple example: you have two I/O watchers (for |
|
|
598 | example, STDOUT and STDERR for a program), and you want to wait for |
|
|
599 | both streams to close before activating a condvar: |
|
|
600 | |
|
|
601 | my $cv = AnyEvent->condvar; |
|
|
602 | |
|
|
603 | $cv->begin; # first watcher |
|
|
604 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
|
|
605 | defined sysread $fh1, my $buf, 4096 |
|
|
606 | or $cv->end; |
|
|
607 | }); |
|
|
608 | |
|
|
609 | $cv->begin; # second watcher |
|
|
610 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
|
|
611 | defined sysread $fh2, my $buf, 4096 |
|
|
612 | or $cv->end; |
|
|
613 | }); |
|
|
614 | |
|
|
615 | $cv->recv; |
|
|
616 | |
|
|
617 | This works because for every event source (EOF on file handle), |
|
|
618 | there is one call to "begin", so the condvar waits for all calls to |
|
|
619 | "end" before sending. |
|
|
620 | |
|
|
621 | The ping example mentioned above is slightly more complicated, as |
|
|
622 | the there are results to be passwd back, and the number of tasks |
|
|
623 | that are begung can potentially be zero: |
412 | |
624 | |
413 | my $cv = AnyEvent->condvar; |
625 | my $cv = AnyEvent->condvar; |
414 | |
626 | |
415 | my %result; |
627 | my %result; |
416 | $cv->begin (sub { $cv->send (\%result) }); |
628 | $cv->begin (sub { $cv->send (\%result) }); |
… | |
… | |
436 | the loop, which serves two important purposes: first, it sets the |
648 | the loop, which serves two important purposes: first, it sets the |
437 | callback to be called once the counter reaches 0, and second, it |
649 | callback to be called once the counter reaches 0, and second, it |
438 | ensures that "send" is called even when "no" hosts are being pinged |
650 | ensures that "send" is called even when "no" hosts are being pinged |
439 | (the loop doesn't execute once). |
651 | (the loop doesn't execute once). |
440 | |
652 | |
441 | This is the general pattern when you "fan out" into multiple |
653 | This is the general pattern when you "fan out" into multiple (but |
442 | subrequests: use an outer "begin"/"end" pair to set the callback and |
654 | potentially none) subrequests: use an outer "begin"/"end" pair to |
443 | ensure "end" is called at least once, and then, for each subrequest |
655 | set the callback and ensure "end" is called at least once, and then, |
444 | you start, call "begin" and for each subrequest you finish, call |
656 | for each subrequest you start, call "begin" and for each subrequest |
445 | "end". |
657 | you finish, call "end". |
446 | |
658 | |
447 | METHODS FOR CONSUMERS |
659 | METHODS FOR CONSUMERS |
448 | These methods should only be used by the consuming side, i.e. the code |
660 | These methods should only be used by the consuming side, i.e. the code |
449 | awaits the condition. |
661 | awaits the condition. |
450 | |
662 | |
… | |
… | |
488 | |
700 | |
489 | $bool = $cv->ready |
701 | $bool = $cv->ready |
490 | Returns true when the condition is "true", i.e. whether "send" or |
702 | Returns true when the condition is "true", i.e. whether "send" or |
491 | "croak" have been called. |
703 | "croak" have been called. |
492 | |
704 | |
493 | $cb = $cv->cb ([new callback]) |
705 | $cb = $cv->cb ($cb->($cv)) |
494 | This is a mutator function that returns the callback set and |
706 | This is a mutator function that returns the callback set and |
495 | optionally replaces it before doing so. |
707 | optionally replaces it before doing so. |
496 | |
708 | |
497 | The callback will be called when the condition becomes "true", i.e. |
709 | The callback will be called when the condition becomes "true", i.e. |
498 | when "send" or "croak" are called. Calling "recv" inside the |
710 | when "send" or "croak" are called, with the only argument being the |
|
|
711 | condition variable itself. Calling "recv" inside the callback or at |
499 | callback or at any later time is guaranteed not to block. |
712 | any later time is guaranteed not to block. |
|
|
713 | |
|
|
714 | SUPPORTED EVENT LOOPS/BACKENDS |
|
|
715 | The available backend classes are (every class has its own manpage): |
|
|
716 | |
|
|
717 | Backends that are autoprobed when no other event loop can be found. |
|
|
718 | EV is the preferred backend when no other event loop seems to be in |
|
|
719 | use. If EV is not installed, then AnyEvent will try Event, and, |
|
|
720 | failing that, will fall back to its own pure-perl implementation, |
|
|
721 | which is available everywhere as it comes with AnyEvent itself. |
|
|
722 | |
|
|
723 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
|
|
724 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
725 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
726 | |
|
|
727 | Backends that are transparently being picked up when they are used. |
|
|
728 | These will be used when they are currently loaded when the first |
|
|
729 | watcher is created, in which case it is assumed that the application |
|
|
730 | is using them. This means that AnyEvent will automatically pick the |
|
|
731 | right backend when the main program loads an event module before |
|
|
732 | anything starts to create watchers. Nothing special needs to be done |
|
|
733 | by the main program. |
|
|
734 | |
|
|
735 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
|
|
736 | AnyEvent::Impl::Tk based on Tk, very broken. |
|
|
737 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
738 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
739 | |
|
|
740 | Backends with special needs. |
|
|
741 | Qt requires the Qt::Application to be instantiated first, but will |
|
|
742 | otherwise be picked up automatically. As long as the main program |
|
|
743 | instantiates the application before any AnyEvent watchers are |
|
|
744 | created, everything should just work. |
|
|
745 | |
|
|
746 | AnyEvent::Impl::Qt based on Qt. |
|
|
747 | |
|
|
748 | Support for IO::Async can only be partial, as it is too broken and |
|
|
749 | architecturally limited to even support the AnyEvent API. It also is |
|
|
750 | the only event loop that needs the loop to be set explicitly, so it |
|
|
751 | can only be used by a main program knowing about AnyEvent. See |
|
|
752 | AnyEvent::Impl::Async for the gory details. |
|
|
753 | |
|
|
754 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
755 | |
|
|
756 | Event loops that are indirectly supported via other backends. |
|
|
757 | Some event loops can be supported via other modules: |
|
|
758 | |
|
|
759 | There is no direct support for WxWidgets (Wx) or Prima. |
|
|
760 | |
|
|
761 | WxWidgets has no support for watching file handles. However, you can |
|
|
762 | use WxWidgets through the POE adaptor, as POE has a Wx backend that |
|
|
763 | simply polls 20 times per second, which was considered to be too |
|
|
764 | horrible to even consider for AnyEvent. |
|
|
765 | |
|
|
766 | Prima is not supported as nobody seems to be using it, but it has a |
|
|
767 | POE backend, so it can be supported through POE. |
|
|
768 | |
|
|
769 | AnyEvent knows about both Prima and Wx, however, and will try to |
|
|
770 | load POE when detecting them, in the hope that POE will pick them |
|
|
771 | up, in which case everything will be automatic. |
500 | |
772 | |
501 | GLOBAL VARIABLES AND FUNCTIONS |
773 | GLOBAL VARIABLES AND FUNCTIONS |
|
|
774 | These are not normally required to use AnyEvent, but can be useful to |
|
|
775 | write AnyEvent extension modules. |
|
|
776 | |
502 | $AnyEvent::MODEL |
777 | $AnyEvent::MODEL |
503 | Contains "undef" until the first watcher is being created. Then it |
778 | Contains "undef" until the first watcher is being created, before |
|
|
779 | the backend has been autodetected. |
|
|
780 | |
504 | contains the event model that is being used, which is the name of |
781 | Afterwards it contains the event model that is being used, which is |
505 | the Perl class implementing the model. This class is usually one of |
782 | the name of the Perl class implementing the model. This class is |
506 | the "AnyEvent::Impl:xxx" modules, but can be any other class in the |
783 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
507 | case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). |
784 | other class in the case AnyEvent has been extended at runtime (e.g. |
508 | |
785 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
509 | The known classes so far are: |
|
|
510 | |
|
|
511 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
|
|
512 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
513 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
514 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
515 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
|
|
516 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
517 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
518 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
519 | |
|
|
520 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
521 | watching file handles. However, you can use WxWidgets through the |
|
|
522 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
523 | second, which was considered to be too horrible to even consider for |
|
|
524 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by |
|
|
525 | using it's adaptor. |
|
|
526 | |
|
|
527 | AnyEvent knows about Prima and Wx and will try to use POE when |
|
|
528 | autodetecting them. |
|
|
529 | |
786 | |
530 | AnyEvent::detect |
787 | AnyEvent::detect |
531 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
788 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
532 | if necessary. You should only call this function right before you |
789 | if necessary. You should only call this function right before you |
533 | would have created an AnyEvent watcher anyway, that is, as late as |
790 | would have created an AnyEvent watcher anyway, that is, as late as |
534 | possible at runtime. |
791 | possible at runtime, and not e.g. while initialising of your module. |
|
|
792 | |
|
|
793 | If you need to do some initialisation before AnyEvent watchers are |
|
|
794 | created, use "post_detect". |
535 | |
795 | |
536 | $guard = AnyEvent::post_detect { BLOCK } |
796 | $guard = AnyEvent::post_detect { BLOCK } |
537 | Arranges for the code block to be executed as soon as the event |
797 | Arranges for the code block to be executed as soon as the event |
538 | model is autodetected (or immediately if this has already happened). |
798 | model is autodetected (or immediately if this has already happened). |
|
|
799 | |
|
|
800 | The block will be executed *after* the actual backend has been |
|
|
801 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
|
|
802 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
|
|
803 | other initialisations - see the sources of AnyEvent::Strict or |
|
|
804 | AnyEvent::AIO to see how this is used. |
|
|
805 | |
|
|
806 | The most common usage is to create some global watchers, without |
|
|
807 | forcing event module detection too early, for example, AnyEvent::AIO |
|
|
808 | creates and installs the global IO::AIO watcher in a "post_detect" |
|
|
809 | block to avoid autodetecting the event module at load time. |
539 | |
810 | |
540 | If called in scalar or list context, then it creates and returns an |
811 | If called in scalar or list context, then it creates and returns an |
541 | object that automatically removes the callback again when it is |
812 | object that automatically removes the callback again when it is |
542 | destroyed. See Coro::BDB for a case where this is useful. |
813 | destroyed. See Coro::BDB for a case where this is useful. |
543 | |
814 | |
… | |
… | |
545 | If there are any code references in this array (you can "push" to it |
816 | If there are any code references in this array (you can "push" to it |
546 | before or after loading AnyEvent), then they will called directly |
817 | before or after loading AnyEvent), then they will called directly |
547 | after the event loop has been chosen. |
818 | after the event loop has been chosen. |
548 | |
819 | |
549 | You should check $AnyEvent::MODEL before adding to this array, |
820 | You should check $AnyEvent::MODEL before adding to this array, |
550 | though: if it contains a true value then the event loop has already |
821 | though: if it is defined then the event loop has already been |
551 | been detected, and the array will be ignored. |
822 | detected, and the array will be ignored. |
552 | |
823 | |
553 | Best use "AnyEvent::post_detect { BLOCK }" instead. |
824 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
|
|
825 | allows it,as it takes care of these details. |
|
|
826 | |
|
|
827 | This variable is mainly useful for modules that can do something |
|
|
828 | useful when AnyEvent is used and thus want to know when it is |
|
|
829 | initialised, but do not need to even load it by default. This array |
|
|
830 | provides the means to hook into AnyEvent passively, without loading |
|
|
831 | it. |
554 | |
832 | |
555 | WHAT TO DO IN A MODULE |
833 | WHAT TO DO IN A MODULE |
556 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
834 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
557 | freely, but you should not load a specific event module or rely on it. |
835 | freely, but you should not load a specific event module or rely on it. |
558 | |
836 | |
… | |
… | |
578 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
856 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
579 | do anything special (it does not need to be event-based) and let |
857 | do anything special (it does not need to be event-based) and let |
580 | AnyEvent decide which implementation to chose if some module relies on |
858 | AnyEvent decide which implementation to chose if some module relies on |
581 | it. |
859 | it. |
582 | |
860 | |
583 | If the main program relies on a specific event model. For example, in |
861 | If the main program relies on a specific event model - for example, in |
584 | Gtk2 programs you have to rely on the Glib module. You should load the |
862 | Gtk2 programs you have to rely on the Glib module - you should load the |
585 | event module before loading AnyEvent or any module that uses it: |
863 | event module before loading AnyEvent or any module that uses it: |
586 | generally speaking, you should load it as early as possible. The reason |
864 | generally speaking, you should load it as early as possible. The reason |
587 | is that modules might create watchers when they are loaded, and AnyEvent |
865 | is that modules might create watchers when they are loaded, and AnyEvent |
588 | will decide on the event model to use as soon as it creates watchers, |
866 | will decide on the event model to use as soon as it creates watchers, |
589 | and it might chose the wrong one unless you load the correct one |
867 | and it might chose the wrong one unless you load the correct one |
590 | yourself. |
868 | yourself. |
591 | |
869 | |
592 | You can chose to use a rather inefficient pure-perl implementation by |
870 | You can chose to use a pure-perl implementation by loading the |
593 | loading the "AnyEvent::Impl::Perl" module, which gives you similar |
871 | "AnyEvent::Impl::Perl" module, which gives you similar behaviour |
594 | behaviour everywhere, but letting AnyEvent chose is generally better. |
872 | everywhere, but letting AnyEvent chose the model is generally better. |
|
|
873 | |
|
|
874 | MAINLOOP EMULATION |
|
|
875 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
876 | only want to use AnyEvent), you do not want to run a specific event |
|
|
877 | loop. |
|
|
878 | |
|
|
879 | In that case, you can use a condition variable like this: |
|
|
880 | |
|
|
881 | AnyEvent->condvar->recv; |
|
|
882 | |
|
|
883 | This has the effect of entering the event loop and looping forever. |
|
|
884 | |
|
|
885 | Note that usually your program has some exit condition, in which case it |
|
|
886 | is better to use the "traditional" approach of storing a condition |
|
|
887 | variable somewhere, waiting for it, and sending it when the program |
|
|
888 | should exit cleanly. |
595 | |
889 | |
596 | OTHER MODULES |
890 | OTHER MODULES |
597 | The following is a non-exhaustive list of additional modules that use |
891 | The following is a non-exhaustive list of additional modules that use |
598 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
892 | AnyEvent as a client and can therefore be mixed easily with other |
599 | in the same program. Some of the modules come with AnyEvent, some are |
893 | AnyEvent modules and other event loops in the same program. Some of the |
600 | available via CPAN. |
894 | modules come with AnyEvent, most are available via CPAN. |
601 | |
895 | |
602 | AnyEvent::Util |
896 | AnyEvent::Util |
603 | Contains various utility functions that replace often-used but |
897 | Contains various utility functions that replace often-used but |
604 | blocking functions such as "inet_aton" by event-/callback-based |
898 | blocking functions such as "inet_aton" by event-/callback-based |
605 | versions. |
899 | versions. |
606 | |
|
|
607 | AnyEvent::Handle |
|
|
608 | Provide read and write buffers and manages watchers for reads and |
|
|
609 | writes. |
|
|
610 | |
900 | |
611 | AnyEvent::Socket |
901 | AnyEvent::Socket |
612 | Provides various utility functions for (internet protocol) sockets, |
902 | Provides various utility functions for (internet protocol) sockets, |
613 | addresses and name resolution. Also functions to create non-blocking |
903 | addresses and name resolution. Also functions to create non-blocking |
614 | tcp connections or tcp servers, with IPv6 and SRV record support and |
904 | tcp connections or tcp servers, with IPv6 and SRV record support and |
615 | more. |
905 | more. |
616 | |
906 | |
|
|
907 | AnyEvent::Handle |
|
|
908 | Provide read and write buffers, manages watchers for reads and |
|
|
909 | writes, supports raw and formatted I/O, I/O queued and fully |
|
|
910 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
|
|
911 | |
|
|
912 | AnyEvent::DNS |
|
|
913 | Provides rich asynchronous DNS resolver capabilities. |
|
|
914 | |
|
|
915 | AnyEvent::HTTP |
|
|
916 | A simple-to-use HTTP library that is capable of making a lot of |
|
|
917 | concurrent HTTP requests. |
|
|
918 | |
617 | AnyEvent::HTTPD |
919 | AnyEvent::HTTPD |
618 | Provides a simple web application server framework. |
920 | Provides a simple web application server framework. |
619 | |
921 | |
620 | AnyEvent::DNS |
|
|
621 | Provides rich asynchronous DNS resolver capabilities. |
|
|
622 | |
|
|
623 | AnyEvent::FastPing |
922 | AnyEvent::FastPing |
624 | The fastest ping in the west. |
923 | The fastest ping in the west. |
625 | |
924 | |
|
|
925 | AnyEvent::DBI |
|
|
926 | Executes DBI requests asynchronously in a proxy process. |
|
|
927 | |
|
|
928 | AnyEvent::AIO |
|
|
929 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
930 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
931 | together. |
|
|
932 | |
|
|
933 | AnyEvent::BDB |
|
|
934 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
935 | fuses BDB and AnyEvent together. |
|
|
936 | |
|
|
937 | AnyEvent::GPSD |
|
|
938 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
939 | information. |
|
|
940 | |
|
|
941 | AnyEvent::IRC |
|
|
942 | AnyEvent based IRC client module family (replacing the older |
626 | Net::IRC3 |
943 | Net::IRC3). |
627 | AnyEvent based IRC client module family. |
|
|
628 | |
944 | |
629 | Net::XMPP2 |
945 | AnyEvent::XMPP |
630 | AnyEvent based XMPP (Jabber protocol) module family. |
946 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
947 | older Net::XMPP2>. |
|
|
948 | |
|
|
949 | AnyEvent::IGS |
|
|
950 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
951 | App::IGS). |
631 | |
952 | |
632 | Net::FCP |
953 | Net::FCP |
633 | AnyEvent-based implementation of the Freenet Client Protocol, |
954 | AnyEvent-based implementation of the Freenet Client Protocol, |
634 | birthplace of AnyEvent. |
955 | birthplace of AnyEvent. |
635 | |
956 | |
… | |
… | |
637 | High level API for event-based execution flow control. |
958 | High level API for event-based execution flow control. |
638 | |
959 | |
639 | Coro |
960 | Coro |
640 | Has special support for AnyEvent via Coro::AnyEvent. |
961 | Has special support for AnyEvent via Coro::AnyEvent. |
641 | |
962 | |
642 | AnyEvent::AIO, IO::AIO |
963 | ERROR AND EXCEPTION HANDLING |
643 | Truly asynchronous I/O, should be in the toolbox of every event |
964 | In general, AnyEvent does not do any error handling - it relies on the |
644 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
965 | caller to do that if required. The AnyEvent::Strict module (see also the |
645 | together. |
966 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
|
|
967 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
968 | development. |
646 | |
969 | |
647 | AnyEvent::BDB, BDB |
970 | As for exception handling (i.e. runtime errors and exceptions thrown |
648 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently |
971 | while executing a callback), this is not only highly event-loop |
649 | fuses IO::AIO and AnyEvent together. |
972 | specific, but also not in any way wrapped by this module, as this is the |
|
|
973 | job of the main program. |
650 | |
974 | |
651 | IO::Lambda |
975 | The pure perl event loop simply re-throws the exception (usually within |
652 | The lambda approach to I/O - don't ask, look there. Can use |
976 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
653 | AnyEvent. |
977 | Glib uses "install_exception_handler" and so on. |
654 | |
|
|
655 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
656 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
657 | in a module. This section is only of use to event loop authors who want |
|
|
658 | to provide AnyEvent compatibility. |
|
|
659 | |
|
|
660 | If you need to support another event library which isn't directly |
|
|
661 | supported by AnyEvent, you can supply your own interface to it by |
|
|
662 | pushing, before the first watcher gets created, the package name of the |
|
|
663 | event module and the package name of the interface to use onto |
|
|
664 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
665 | AnyEvent, so it is reasonably cheap. |
|
|
666 | |
|
|
667 | Example: |
|
|
668 | |
|
|
669 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
670 | |
|
|
671 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
672 | package/class when it finds the "urxvt" package/module is already |
|
|
673 | loaded. |
|
|
674 | |
|
|
675 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
676 | will first check for the presence of urxvt by trying to "use" the |
|
|
677 | "urxvt::anyevent" module. |
|
|
678 | |
|
|
679 | The class should provide implementations for all watcher types. See |
|
|
680 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
681 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
682 | the sources. |
|
|
683 | |
|
|
684 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
685 | provide suitable (hopefully) replacements. |
|
|
686 | |
|
|
687 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
688 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
689 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
690 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
691 | part of the *rxvt-unicode* distribution. |
|
|
692 | |
|
|
693 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
694 | condition variables: code blocking while waiting for a condition will |
|
|
695 | "die". This still works with most modules/usages, and blocking calls |
|
|
696 | must not be done in an interactive application, so it makes sense. |
|
|
697 | |
978 | |
698 | ENVIRONMENT VARIABLES |
979 | ENVIRONMENT VARIABLES |
699 | The following environment variables are used by this module: |
980 | The following environment variables are used by this module or its |
|
|
981 | submodules. |
|
|
982 | |
|
|
983 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
984 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
985 | enabled. |
700 | |
986 | |
701 | "PERL_ANYEVENT_VERBOSE" |
987 | "PERL_ANYEVENT_VERBOSE" |
702 | By default, AnyEvent will be completely silent except in fatal |
988 | By default, AnyEvent will be completely silent except in fatal |
703 | conditions. You can set this environment variable to make AnyEvent |
989 | conditions. You can set this environment variable to make AnyEvent |
704 | more talkative. |
990 | more talkative. |
… | |
… | |
707 | conditions, such as not being able to load the event model specified |
993 | conditions, such as not being able to load the event model specified |
708 | by "PERL_ANYEVENT_MODEL". |
994 | by "PERL_ANYEVENT_MODEL". |
709 | |
995 | |
710 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
996 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
711 | event model it chooses. |
997 | event model it chooses. |
|
|
998 | |
|
|
999 | "PERL_ANYEVENT_STRICT" |
|
|
1000 | AnyEvent does not do much argument checking by default, as thorough |
|
|
1001 | argument checking is very costly. Setting this variable to a true |
|
|
1002 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
|
|
1003 | thoroughly check the arguments passed to most method calls. If it |
|
|
1004 | finds any problems, it will croak. |
|
|
1005 | |
|
|
1006 | In other words, enables "strict" mode. |
|
|
1007 | |
|
|
1008 | Unlike "use strict", it is definitely recommended to keep it off in |
|
|
1009 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
|
|
1010 | while developing programs can be very useful, however. |
712 | |
1011 | |
713 | "PERL_ANYEVENT_MODEL" |
1012 | "PERL_ANYEVENT_MODEL" |
714 | This can be used to specify the event model to be used by AnyEvent, |
1013 | This can be used to specify the event model to be used by AnyEvent, |
715 | before auto detection and -probing kicks in. It must be a string |
1014 | before auto detection and -probing kicks in. It must be a string |
716 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1015 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
721 | This functionality might change in future versions. |
1020 | This functionality might change in future versions. |
722 | |
1021 | |
723 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
1022 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
724 | could start your program like this: |
1023 | could start your program like this: |
725 | |
1024 | |
726 | PERL_ANYEVENT_MODEL=Perl perl ... |
1025 | PERL_ANYEVENT_MODEL=Perl perl ... |
727 | |
1026 | |
728 | "PERL_ANYEVENT_PROTOCOLS" |
1027 | "PERL_ANYEVENT_PROTOCOLS" |
729 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
1028 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
730 | preferences for IPv4 or IPv6. The default is unspecified (and might |
1029 | preferences for IPv4 or IPv6. The default is unspecified (and might |
731 | change, or be the result of auto probing). |
1030 | change, or be the result of auto probing). |
… | |
… | |
735 | mentioned will be used, and preference will be given to protocols |
1034 | mentioned will be used, and preference will be given to protocols |
736 | mentioned earlier in the list. |
1035 | mentioned earlier in the list. |
737 | |
1036 | |
738 | This variable can effectively be used for denial-of-service attacks |
1037 | This variable can effectively be used for denial-of-service attacks |
739 | against local programs (e.g. when setuid), although the impact is |
1038 | against local programs (e.g. when setuid), although the impact is |
740 | likely small, as the program has to handle connection errors |
1039 | likely small, as the program has to handle conenction and other |
741 | already- |
1040 | failures anyways. |
742 | |
1041 | |
743 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
1042 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
744 | IPv6, but support both and try to use both. |
1043 | IPv6, but support both and try to use both. |
745 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1044 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
746 | resolve or contact IPv6 addresses. |
1045 | resolve or contact IPv6 addresses. |
… | |
… | |
753 | but some (broken) firewalls drop such DNS packets, which is why it |
1052 | but some (broken) firewalls drop such DNS packets, which is why it |
754 | is off by default. |
1053 | is off by default. |
755 | |
1054 | |
756 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
1055 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
757 | EDNS0 in its DNS requests. |
1056 | EDNS0 in its DNS requests. |
|
|
1057 | |
|
|
1058 | "PERL_ANYEVENT_MAX_FORKS" |
|
|
1059 | The maximum number of child processes that |
|
|
1060 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
1061 | |
|
|
1062 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
|
|
1063 | The default value for the "max_outstanding" parameter for the |
|
|
1064 | default DNS resolver - this is the maximum number of parallel DNS |
|
|
1065 | requests that are sent to the DNS server. |
|
|
1066 | |
|
|
1067 | "PERL_ANYEVENT_RESOLV_CONF" |
|
|
1068 | The file to use instead of /etc/resolv.conf (or OS-specific |
|
|
1069 | configuration) in the default resolver. When set to the empty |
|
|
1070 | string, no default config will be used. |
|
|
1071 | |
|
|
1072 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
|
|
1073 | When neither "ca_file" nor "ca_path" was specified during |
|
|
1074 | AnyEvent::TLS context creation, and either of these environment |
|
|
1075 | variables exist, they will be used to specify CA certificate |
|
|
1076 | locations instead of a system-dependent default. |
|
|
1077 | |
|
|
1078 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1079 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
1080 | in a module. This section is only of use to event loop authors who want |
|
|
1081 | to provide AnyEvent compatibility. |
|
|
1082 | |
|
|
1083 | If you need to support another event library which isn't directly |
|
|
1084 | supported by AnyEvent, you can supply your own interface to it by |
|
|
1085 | pushing, before the first watcher gets created, the package name of the |
|
|
1086 | event module and the package name of the interface to use onto |
|
|
1087 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
1088 | AnyEvent, so it is reasonably cheap. |
|
|
1089 | |
|
|
1090 | Example: |
|
|
1091 | |
|
|
1092 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
1093 | |
|
|
1094 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
1095 | package/class when it finds the "urxvt" package/module is already |
|
|
1096 | loaded. |
|
|
1097 | |
|
|
1098 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
1099 | will first check for the presence of urxvt by trying to "use" the |
|
|
1100 | "urxvt::anyevent" module. |
|
|
1101 | |
|
|
1102 | The class should provide implementations for all watcher types. See |
|
|
1103 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
1104 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
1105 | the sources. |
|
|
1106 | |
|
|
1107 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
1108 | provide suitable (hopefully) replacements. |
|
|
1109 | |
|
|
1110 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
1111 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
1112 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
1113 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
1114 | part of the *rxvt-unicode* distribution. |
|
|
1115 | |
|
|
1116 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
1117 | condition variables: code blocking while waiting for a condition will |
|
|
1118 | "die". This still works with most modules/usages, and blocking calls |
|
|
1119 | must not be done in an interactive application, so it makes sense. |
758 | |
1120 | |
759 | EXAMPLE PROGRAM |
1121 | EXAMPLE PROGRAM |
760 | The following program uses an I/O watcher to read data from STDIN, a |
1122 | The following program uses an I/O watcher to read data from STDIN, a |
761 | timer to display a message once per second, and a condition variable to |
1123 | timer to display a message once per second, and a condition variable to |
762 | quit the program when the user enters quit: |
1124 | quit the program when the user enters quit: |
… | |
… | |
949 | *destroy* is the time, in microseconds, that it takes to destroy a |
1311 | *destroy* is the time, in microseconds, that it takes to destroy a |
950 | single watcher. |
1312 | single watcher. |
951 | |
1313 | |
952 | Results |
1314 | Results |
953 | name watchers bytes create invoke destroy comment |
1315 | name watchers bytes create invoke destroy comment |
954 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1316 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
955 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1317 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
956 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1318 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
957 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1319 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
958 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1320 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
959 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
1321 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1322 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
|
|
1323 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
960 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1324 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
961 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1325 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
962 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1326 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
963 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1327 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
964 | |
1328 | |
965 | Discussion |
1329 | Discussion |
966 | The benchmark does *not* measure scalability of the event loop very |
1330 | The benchmark does *not* measure scalability of the event loop very |
967 | well. For example, a select-based event loop (such as the pure perl one) |
1331 | well. For example, a select-based event loop (such as the pure perl one) |
968 | can never compete with an event loop that uses epoll when the number of |
1332 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
993 | few of them active), of course, but this was not subject of this |
1357 | few of them active), of course, but this was not subject of this |
994 | benchmark. |
1358 | benchmark. |
995 | |
1359 | |
996 | The "Event" module has a relatively high setup and callback invocation |
1360 | The "Event" module has a relatively high setup and callback invocation |
997 | cost, but overall scores in on the third place. |
1361 | cost, but overall scores in on the third place. |
|
|
1362 | |
|
|
1363 | "IO::Async" performs admirably well, about on par with "Event", even |
|
|
1364 | when using its pure perl backend. |
998 | |
1365 | |
999 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1366 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1000 | callback invocation and overall ends up in the same class as "Event". |
1367 | callback invocation and overall ends up in the same class as "Event". |
1001 | However, Glib scales extremely badly, doubling the number of watchers |
1368 | However, Glib scales extremely badly, doubling the number of watchers |
1002 | increases the processing time by more than a factor of four, making it |
1369 | increases the processing time by more than a factor of four, making it |
… | |
… | |
1073 | single "request", that is, reading the token from the pipe and |
1440 | single "request", that is, reading the token from the pipe and |
1074 | forwarding it to another server. This includes deleting the old timeout |
1441 | forwarding it to another server. This includes deleting the old timeout |
1075 | and creating a new one that moves the timeout into the future. |
1442 | and creating a new one that moves the timeout into the future. |
1076 | |
1443 | |
1077 | Results |
1444 | Results |
1078 | name sockets create request |
1445 | name sockets create request |
1079 | EV 20000 69.01 11.16 |
1446 | EV 20000 69.01 11.16 |
1080 | Perl 20000 73.32 35.87 |
1447 | Perl 20000 73.32 35.87 |
|
|
1448 | IOAsync 20000 157.00 98.14 epoll |
|
|
1449 | IOAsync 20000 159.31 616.06 poll |
1081 | Event 20000 212.62 257.32 |
1450 | Event 20000 212.62 257.32 |
1082 | Glib 20000 651.16 1896.30 |
1451 | Glib 20000 651.16 1896.30 |
1083 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1452 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1084 | |
1453 | |
1085 | Discussion |
1454 | Discussion |
1086 | This benchmark *does* measure scalability and overall performance of the |
1455 | This benchmark *does* measure scalability and overall performance of the |
1087 | particular event loop. |
1456 | particular event loop. |
1088 | |
1457 | |
1089 | EV is again fastest. Since it is using epoll on my system, the setup |
1458 | EV is again fastest. Since it is using epoll on my system, the setup |
1090 | time is relatively high, though. |
1459 | time is relatively high, though. |
1091 | |
1460 | |
1092 | Perl surprisingly comes second. It is much faster than the C-based event |
1461 | Perl surprisingly comes second. It is much faster than the C-based event |
1093 | loops Event and Glib. |
1462 | loops Event and Glib. |
|
|
1463 | |
|
|
1464 | IO::Async performs very well when using its epoll backend, and still |
|
|
1465 | quite good compared to Glib when using its pure perl backend. |
1094 | |
1466 | |
1095 | Event suffers from high setup time as well (look at its code and you |
1467 | Event suffers from high setup time as well (look at its code and you |
1096 | will understand why). Callback invocation also has a high overhead |
1468 | will understand why). Callback invocation also has a high overhead |
1097 | compared to the "$_->() for .."-style loop that the Perl event loop |
1469 | compared to the "$_->() for .."-style loop that the Perl event loop |
1098 | uses. Event uses select or poll in basically all documented |
1470 | uses. Event uses select or poll in basically all documented |
… | |
… | |
1149 | |
1521 | |
1150 | Summary |
1522 | Summary |
1151 | * C-based event loops perform very well with small number of watchers, |
1523 | * C-based event loops perform very well with small number of watchers, |
1152 | as the management overhead dominates. |
1524 | as the management overhead dominates. |
1153 | |
1525 | |
|
|
1526 | THE IO::Lambda BENCHMARK |
|
|
1527 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
1528 | could be misinterpreted to make AnyEvent look bad. In fact, the |
|
|
1529 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
|
|
1530 | better (which shouldn't come as a surprise to anybody). As such, the |
|
|
1531 | benchmark is fine, and mostly shows that the AnyEvent backend from |
|
|
1532 | IO::Lambda isn't very optimal. But how would AnyEvent compare when used |
|
|
1533 | without the extra baggage? To explore this, I wrote the equivalent |
|
|
1534 | benchmark for AnyEvent. |
|
|
1535 | |
|
|
1536 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
1537 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
1538 | creates the next connection. This is a rather bad benchmark, as it |
|
|
1539 | doesn't test the efficiency of the framework or much non-blocking I/O, |
|
|
1540 | but it is a benchmark nevertheless. |
|
|
1541 | |
|
|
1542 | name runtime |
|
|
1543 | Lambda/select 0.330 sec |
|
|
1544 | + optimized 0.122 sec |
|
|
1545 | Lambda/AnyEvent 0.327 sec |
|
|
1546 | + optimized 0.138 sec |
|
|
1547 | Raw sockets/select 0.077 sec |
|
|
1548 | POE/select, components 0.662 sec |
|
|
1549 | POE/select, raw sockets 0.226 sec |
|
|
1550 | POE/select, optimized 0.404 sec |
|
|
1551 | |
|
|
1552 | AnyEvent/select/nb 0.085 sec |
|
|
1553 | AnyEvent/EV/nb 0.068 sec |
|
|
1554 | +state machine 0.134 sec |
|
|
1555 | |
|
|
1556 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
|
|
1557 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
1558 | defeating the purpose of an event-based solution. All of the newly |
|
|
1559 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
1560 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
1561 | resolver), so AnyEvent is at a disadvantage here, as non-blocking |
|
|
1562 | connects generally require a lot more bookkeeping and event handling |
|
|
1563 | than blocking connects (which involve a single syscall only). |
|
|
1564 | |
|
|
1565 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
|
|
1566 | offers similar expressive power as POE and IO::Lambda, using |
|
|
1567 | conventional Perl syntax. This means that both the echo server and the |
|
|
1568 | client are 100% non-blocking, further placing it at a disadvantage. |
|
|
1569 | |
|
|
1570 | As you can see, the AnyEvent + EV combination even beats the |
|
|
1571 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
|
|
1572 | backend easily beats IO::Lambda and POE. |
|
|
1573 | |
|
|
1574 | And even the 100% non-blocking version written using the high-level (and |
|
|
1575 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
|
|
1576 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
|
|
1577 | in a non-blocking way. |
|
|
1578 | |
|
|
1579 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
|
|
1580 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
|
|
1581 | part of the IO::lambda distribution and were used without any changes. |
|
|
1582 | |
|
|
1583 | SIGNALS |
|
|
1584 | AnyEvent currently installs handlers for these signals: |
|
|
1585 | |
|
|
1586 | SIGCHLD |
|
|
1587 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
|
|
1588 | emulation for event loops that do not support them natively. Also, |
|
|
1589 | some event loops install a similar handler. |
|
|
1590 | |
|
|
1591 | Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, |
|
|
1592 | then AnyEvent will reset it to default, to avoid losing child exit |
|
|
1593 | statuses. |
|
|
1594 | |
|
|
1595 | SIGPIPE |
|
|
1596 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
|
|
1597 | "undef" when AnyEvent gets loaded. |
|
|
1598 | |
|
|
1599 | The rationale for this is that AnyEvent users usually do not really |
|
|
1600 | depend on SIGPIPE delivery (which is purely an optimisation for |
|
|
1601 | shell use, or badly-written programs), but "SIGPIPE" can cause |
|
|
1602 | spurious and rare program exits as a lot of people do not expect |
|
|
1603 | "SIGPIPE" when writing to some random socket. |
|
|
1604 | |
|
|
1605 | The rationale for installing a no-op handler as opposed to ignoring |
|
|
1606 | it is that this way, the handler will be restored to defaults on |
|
|
1607 | exec. |
|
|
1608 | |
|
|
1609 | Feel free to install your own handler, or reset it to defaults. |
|
|
1610 | |
1154 | FORK |
1611 | FORK |
1155 | Most event libraries are not fork-safe. The ones who are usually are |
1612 | Most event libraries are not fork-safe. The ones who are usually are |
1156 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1613 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1157 | Only EV is fully fork-aware. |
1614 | Only EV is fully fork-aware. |
1158 | |
1615 | |
… | |
… | |
1168 | model than specified in the variable. |
1625 | model than specified in the variable. |
1169 | |
1626 | |
1170 | You can make AnyEvent completely ignore this variable by deleting it |
1627 | You can make AnyEvent completely ignore this variable by deleting it |
1171 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1628 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1172 | |
1629 | |
1173 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1630 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1174 | |
1631 | |
1175 | use AnyEvent; |
1632 | use AnyEvent; |
1176 | |
1633 | |
1177 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1634 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1178 | be used to probe what backend is used and gain other information (which |
1635 | be used to probe what backend is used and gain other information (which |
1179 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
1636 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
|
|
1637 | and $ENV{PERL_ANYEVENT_STRICT}. |
|
|
1638 | |
|
|
1639 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1640 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1641 | enabled. |
|
|
1642 | |
|
|
1643 | BUGS |
|
|
1644 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
|
|
1645 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
|
|
1646 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
|
|
1647 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
|
|
1648 | not as pronounced). |
1180 | |
1649 | |
1181 | SEE ALSO |
1650 | SEE ALSO |
1182 | Utility functions: AnyEvent::Util. |
1651 | Utility functions: AnyEvent::Util. |
1183 | |
1652 | |
1184 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1653 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1185 | Event::Lib, Qt, POE. |
1654 | Event::Lib, Qt, POE. |
1186 | |
1655 | |
1187 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1656 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1188 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1657 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1189 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
1658 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
|
|
1659 | AnyEvent::Impl::IOAsync. |
1190 | |
1660 | |
1191 | Non-blocking file handles, sockets, TCP clients and servers: |
1661 | Non-blocking file handles, sockets, TCP clients and servers: |
1192 | AnyEvent::Handle, AnyEvent::Socket. |
1662 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1193 | |
1663 | |
1194 | Asynchronous DNS: AnyEvent::DNS. |
1664 | Asynchronous DNS: AnyEvent::DNS. |
1195 | |
1665 | |
1196 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1666 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1197 | |
1667 | |
1198 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1668 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
|
|
1669 | AnyEvent::HTTP. |
1199 | |
1670 | |
1200 | AUTHOR |
1671 | AUTHOR |
1201 | Marc Lehmann <schmorp@schmorp.de> |
1672 | Marc Lehmann <schmorp@schmorp.de> |
1202 | http://home.schmorp.de/ |
1673 | http://home.schmorp.de/ |
1203 | |
1674 | |