1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | AnyEvent - provide framework for multiple event loops |
3 | AnyEvent - provide framework for multiple event loops |
4 | |
4 | |
5 | EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt - various supported event loops |
5 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
6 | |
6 | |
7 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
8 | |
8 | |
9 | use AnyEvent; |
9 | use AnyEvent; |
10 | |
10 | |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... }); |
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12 | |
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13 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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14 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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15 | |
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16 | print AnyEvent->now; # prints current event loop time |
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17 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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18 | |
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19 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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20 | |
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21 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
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22 | my ($pid, $status) = @_; |
12 | ... |
23 | ... |
13 | }); |
24 | }); |
14 | |
25 | |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
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16 | ... |
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17 | }); |
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18 | |
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19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
26 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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27 | $w->send; # wake up current and all future recv's |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
28 | $w->recv; # enters "main loop" till $condvar gets ->send |
21 | $w->broadcast; # wake up current and all future wait's |
29 | # use a condvar in callback mode: |
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30 | $w->cb (sub { $_[0]->recv }); |
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31 | |
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32 | =head1 INTRODUCTION/TUTORIAL |
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33 | |
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34 | This manpage is mainly a reference manual. If you are interested |
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35 | in a tutorial or some gentle introduction, have a look at the |
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36 | L<AnyEvent::Intro> manpage. |
22 | |
37 | |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
38 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
24 | |
39 | |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
40 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
26 | nowadays. So what is different about AnyEvent? |
41 | nowadays. So what is different about AnyEvent? |
27 | |
42 | |
28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
43 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
29 | policy> and AnyEvent is I<small and efficient>. |
44 | policy> and AnyEvent is I<small and efficient>. |
30 | |
45 | |
31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
46 | First and foremost, I<AnyEvent is not an event model> itself, it only |
32 | interfaces to whatever event model the main program happens to use in a |
47 | interfaces to whatever event model the main program happens to use, in a |
33 | pragmatic way. For event models and certain classes of immortals alike, |
48 | pragmatic way. For event models and certain classes of immortals alike, |
34 | the statement "there can only be one" is a bitter reality: In general, |
49 | the statement "there can only be one" is a bitter reality: In general, |
35 | only one event loop can be active at the same time in a process. AnyEvent |
50 | only one event loop can be active at the same time in a process. AnyEvent |
36 | helps hiding the differences between those event loops. |
51 | cannot change this, but it can hide the differences between those event |
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52 | loops. |
37 | |
53 | |
38 | The goal of AnyEvent is to offer module authors the ability to do event |
54 | The goal of AnyEvent is to offer module authors the ability to do event |
39 | programming (waiting for I/O or timer events) without subscribing to a |
55 | programming (waiting for I/O or timer events) without subscribing to a |
40 | religion, a way of living, and most importantly: without forcing your |
56 | religion, a way of living, and most importantly: without forcing your |
41 | module users into the same thing by forcing them to use the same event |
57 | module users into the same thing by forcing them to use the same event |
42 | model you use. |
58 | model you use. |
43 | |
59 | |
44 | For modules like POE or IO::Async (which is a total misnomer as it is |
60 | For modules like POE or IO::Async (which is a total misnomer as it is |
45 | actually doing all I/O I<synchronously>...), using them in your module is |
61 | actually doing all I/O I<synchronously>...), using them in your module is |
46 | like joining a cult: After you joined, you are dependent on them and you |
62 | like joining a cult: After you joined, you are dependent on them and you |
47 | cannot use anything else, as it is simply incompatible to everything that |
63 | cannot use anything else, as they are simply incompatible to everything |
48 | isn't itself. What's worse, all the potential users of your module are |
64 | that isn't them. What's worse, all the potential users of your |
49 | I<also> forced to use the same event loop you use. |
65 | module are I<also> forced to use the same event loop you use. |
50 | |
66 | |
51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
67 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
68 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
53 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if |
69 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if |
54 | your module uses one of those, every user of your module has to use it, |
70 | your module uses one of those, every user of your module has to use it, |
55 | too. But if your module uses AnyEvent, it works transparently with all |
71 | too. But if your module uses AnyEvent, it works transparently with all |
56 | event models it supports (including stuff like POE and IO::Async, as long |
72 | event models it supports (including stuff like IO::Async, as long as those |
57 | as those use one of the supported event loops. It is trivial to add new |
73 | use one of the supported event loops. It is trivial to add new event loops |
58 | event loops to AnyEvent, too, so it is future-proof). |
74 | to AnyEvent, too, so it is future-proof). |
59 | |
75 | |
60 | In addition to being free of having to use I<the one and only true event |
76 | In addition to being free of having to use I<the one and only true event |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
77 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
62 | modules, you get an enourmous amount of code and strict rules you have to |
78 | modules, you get an enormous amount of code and strict rules you have to |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
79 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
80 | offering the functionality that is necessary, in as thin as a wrapper as |
65 | technically possible. |
81 | technically possible. |
66 | |
82 | |
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83 | Of course, AnyEvent comes with a big (and fully optional!) toolbox |
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84 | of useful functionality, such as an asynchronous DNS resolver, 100% |
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85 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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86 | such as Windows) and lots of real-world knowledge and workarounds for |
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87 | platform bugs and differences. |
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88 | |
67 | Of course, if you want lots of policy (this can arguably be somewhat |
89 | Now, if you I<do want> lots of policy (this can arguably be somewhat |
68 | useful) and you want to force your users to use the one and only event |
90 | useful) and you want to force your users to use the one and only event |
69 | model, you should I<not> use this module. |
91 | model, you should I<not> use this module. |
70 | |
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71 | |
92 | |
72 | =head1 DESCRIPTION |
93 | =head1 DESCRIPTION |
73 | |
94 | |
74 | L<AnyEvent> provides an identical interface to multiple event loops. This |
95 | L<AnyEvent> provides an identical interface to multiple event loops. This |
75 | allows module authors to utilise an event loop without forcing module |
96 | allows module authors to utilise an event loop without forcing module |
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78 | |
99 | |
79 | The interface itself is vaguely similar, but not identical to the L<Event> |
100 | The interface itself is vaguely similar, but not identical to the L<Event> |
80 | module. |
101 | module. |
81 | |
102 | |
82 | During the first call of any watcher-creation method, the module tries |
103 | During the first call of any watcher-creation method, the module tries |
83 | to detect the currently loaded event loop by probing whether one of |
104 | to detect the currently loaded event loop by probing whether one of the |
84 | the following modules is already loaded: L<Coro::EV>, L<Coro::Event>, |
105 | following modules is already loaded: L<EV>, |
85 | L<EV>, L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>. The first one |
106 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
86 | found is used. If none are found, the module tries to load these modules |
107 | L<POE>. The first one found is used. If none are found, the module tries |
87 | (excluding Event::Lib and Qt) in the order given. The first one that can |
108 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
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109 | adaptor should always succeed) in the order given. The first one that can |
88 | be successfully loaded will be used. If, after this, still none could be |
110 | be successfully loaded will be used. If, after this, still none could be |
89 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
111 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
90 | very efficient, but should work everywhere. |
112 | very efficient, but should work everywhere. |
91 | |
113 | |
92 | Because AnyEvent first checks for modules that are already loaded, loading |
114 | Because AnyEvent first checks for modules that are already loaded, loading |
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102 | starts using it, all bets are off. Maybe you should tell their authors to |
124 | starts using it, all bets are off. Maybe you should tell their authors to |
103 | use AnyEvent so their modules work together with others seamlessly... |
125 | use AnyEvent so their modules work together with others seamlessly... |
104 | |
126 | |
105 | The pure-perl implementation of AnyEvent is called |
127 | The pure-perl implementation of AnyEvent is called |
106 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
128 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
107 | explicitly. |
129 | explicitly and enjoy the high availability of that event loop :) |
108 | |
130 | |
109 | =head1 WATCHERS |
131 | =head1 WATCHERS |
110 | |
132 | |
111 | AnyEvent has the central concept of a I<watcher>, which is an object that |
133 | AnyEvent has the central concept of a I<watcher>, which is an object that |
112 | stores relevant data for each kind of event you are waiting for, such as |
134 | stores relevant data for each kind of event you are waiting for, such as |
113 | the callback to call, the filehandle to watch, etc. |
135 | the callback to call, the file handle to watch, etc. |
114 | |
136 | |
115 | These watchers are normal Perl objects with normal Perl lifetime. After |
137 | These watchers are normal Perl objects with normal Perl lifetime. After |
116 | creating a watcher it will immediately "watch" for events and invoke the |
138 | creating a watcher it will immediately "watch" for events and invoke the |
117 | callback when the event occurs (of course, only when the event model |
139 | callback when the event occurs (of course, only when the event model |
118 | is in control). |
140 | is in control). |
119 | |
141 | |
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142 | Note that B<callbacks must not permanently change global variables> |
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143 | potentially in use by the event loop (such as C<$_> or C<$[>) and that B<< |
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144 | callbacks must not C<die> >>. The former is good programming practise in |
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145 | Perl and the latter stems from the fact that exception handling differs |
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146 | widely between event loops. |
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147 | |
120 | To disable the watcher you have to destroy it (e.g. by setting the |
148 | To disable the watcher you have to destroy it (e.g. by setting the |
121 | variable you store it in to C<undef> or otherwise deleting all references |
149 | variable you store it in to C<undef> or otherwise deleting all references |
122 | to it). |
150 | to it). |
123 | |
151 | |
124 | All watchers are created by calling a method on the C<AnyEvent> class. |
152 | All watchers are created by calling a method on the C<AnyEvent> class. |
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126 | Many watchers either are used with "recursion" (repeating timers for |
154 | Many watchers either are used with "recursion" (repeating timers for |
127 | example), or need to refer to their watcher object in other ways. |
155 | example), or need to refer to their watcher object in other ways. |
128 | |
156 | |
129 | An any way to achieve that is this pattern: |
157 | An any way to achieve that is this pattern: |
130 | |
158 | |
131 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
159 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
132 | # you can use $w here, for example to undef it |
160 | # you can use $w here, for example to undef it |
133 | undef $w; |
161 | undef $w; |
134 | }); |
162 | }); |
135 | |
163 | |
136 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
164 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
137 | my variables are only visible after the statement in which they are |
165 | my variables are only visible after the statement in which they are |
138 | declared. |
166 | declared. |
139 | |
167 | |
140 | =head2 IO WATCHERS |
168 | =head2 I/O WATCHERS |
141 | |
169 | |
142 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
170 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
143 | with the following mandatory key-value pairs as arguments: |
171 | with the following mandatory key-value pairs as arguments: |
144 | |
172 | |
145 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for |
173 | C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch |
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174 | for events (AnyEvent might or might not keep a reference to this file |
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175 | handle). Note that only file handles pointing to things for which |
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176 | non-blocking operation makes sense are allowed. This includes sockets, |
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177 | most character devices, pipes, fifos and so on, but not for example files |
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178 | or block devices. |
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179 | |
146 | events. C<poll> must be a string that is either C<r> or C<w>, which |
180 | C<poll> must be a string that is either C<r> or C<w>, which creates a |
147 | creates a watcher waiting for "r"eadable or "w"ritable events, |
181 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
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182 | |
148 | respectively. C<cb> is the callback to invoke each time the file handle |
183 | C<cb> is the callback to invoke each time the file handle becomes ready. |
149 | becomes ready. |
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150 | |
184 | |
151 | As long as the I/O watcher exists it will keep the file descriptor or a |
185 | Although the callback might get passed parameters, their value and |
152 | copy of it alive/open. |
186 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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187 | callbacks cannot use arguments passed to I/O watcher callbacks. |
153 | |
188 | |
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189 | The I/O watcher might use the underlying file descriptor or a copy of it. |
154 | It is not allowed to close a file handle as long as any watcher is active |
190 | You must not close a file handle as long as any watcher is active on the |
155 | on the underlying file descriptor. |
191 | underlying file descriptor. |
156 | |
192 | |
157 | Some event loops issue spurious readyness notifications, so you should |
193 | Some event loops issue spurious readyness notifications, so you should |
158 | always use non-blocking calls when reading/writing from/to your file |
194 | always use non-blocking calls when reading/writing from/to your file |
159 | handles. |
195 | handles. |
160 | |
196 | |
161 | Example: |
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162 | |
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163 | # wait for readability of STDIN, then read a line and disable the watcher |
197 | Example: wait for readability of STDIN, then read a line and disable the |
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198 | watcher. |
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199 | |
164 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
200 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
165 | chomp (my $input = <STDIN>); |
201 | chomp (my $input = <STDIN>); |
166 | warn "read: $input\n"; |
202 | warn "read: $input\n"; |
167 | undef $w; |
203 | undef $w; |
168 | }); |
204 | }); |
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171 | |
207 | |
172 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
208 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
173 | method with the following mandatory arguments: |
209 | method with the following mandatory arguments: |
174 | |
210 | |
175 | C<after> specifies after how many seconds (fractional values are |
211 | C<after> specifies after how many seconds (fractional values are |
176 | supported) should the timer activate. C<cb> the callback to invoke in that |
212 | supported) the callback should be invoked. C<cb> is the callback to invoke |
177 | case. |
213 | in that case. |
178 | |
214 | |
179 | The timer callback will be invoked at most once: if you want a repeating |
215 | Although the callback might get passed parameters, their value and |
180 | timer you have to create a new watcher (this is a limitation by both Tk |
216 | presence is undefined and you cannot rely on them. Portable AnyEvent |
181 | and Glib). |
217 | callbacks cannot use arguments passed to time watcher callbacks. |
182 | |
218 | |
183 | Example: |
219 | The callback will normally be invoked once only. If you specify another |
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220 | parameter, C<interval>, as a strictly positive number (> 0), then the |
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221 | callback will be invoked regularly at that interval (in fractional |
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222 | seconds) after the first invocation. If C<interval> is specified with a |
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223 | false value, then it is treated as if it were missing. |
184 | |
224 | |
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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 is |
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227 | only approximate. |
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228 | |
185 | # fire an event after 7.7 seconds |
229 | Example: fire an event after 7.7 seconds. |
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230 | |
186 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
231 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
187 | warn "timeout\n"; |
232 | warn "timeout\n"; |
188 | }); |
233 | }); |
189 | |
234 | |
190 | # to cancel the timer: |
235 | # to cancel the timer: |
191 | undef $w; |
236 | undef $w; |
192 | |
237 | |
193 | Example 2: |
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194 | |
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195 | # 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. |
196 | my $w; |
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197 | |
239 | |
198 | my $cb = sub { |
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199 | # cancel the old timer while creating a new one |
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200 | $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"; |
201 | }; |
242 | }; |
202 | |
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203 | # start the "loop" by creating the first watcher |
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204 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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205 | |
243 | |
206 | =head3 TIMING ISSUES |
244 | =head3 TIMING ISSUES |
207 | |
245 | |
208 | There are two ways to handle timers: based on real time (relative, "fire |
246 | There are two ways to handle timers: based on real time (relative, "fire |
209 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
247 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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221 | timers. |
259 | timers. |
222 | |
260 | |
223 | AnyEvent always prefers relative timers, if available, matching the |
261 | AnyEvent always prefers relative timers, if available, matching the |
224 | AnyEvent API. |
262 | AnyEvent API. |
225 | |
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 | =over 4 |
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267 | |
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268 | =item AnyEvent->time |
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269 | |
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270 | This returns the "current wallclock time" as a fractional number of |
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271 | seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time> |
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272 | return, and the result is guaranteed to be compatible with those). |
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273 | |
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274 | It progresses independently of any event loop processing, i.e. each call |
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275 | will check the system clock, which usually gets updated frequently. |
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276 | |
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277 | =item AnyEvent->now |
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278 | |
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279 | This also returns the "current wallclock time", but unlike C<time>, above, |
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280 | this value might change only once per event loop iteration, depending on |
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281 | the event loop (most return the same time as C<time>, above). This is the |
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282 | time that AnyEvent's timers get scheduled against. |
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283 | |
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284 | I<In almost all cases (in all cases if you don't care), this is the |
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285 | function to call when you want to know the current time.> |
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286 | |
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287 | This function is also often faster then C<< AnyEvent->time >>, and |
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288 | thus the preferred method if you want some timestamp (for example, |
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289 | L<AnyEvent::Handle> uses this to update it's activity timeouts). |
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290 | |
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291 | The rest of this section is only of relevance if you try to be very exact |
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292 | with your timing, you can skip it without bad conscience. |
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293 | |
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294 | For a practical example of when these times differ, consider L<Event::Lib> |
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295 | and L<EV> and the following set-up: |
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296 | |
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297 | The event loop is running and has just invoked one of your callback at |
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298 | time=500 (assume no other callbacks delay processing). In your callback, |
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299 | you wait a second by executing C<sleep 1> (blocking the process for a |
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300 | second) and then (at time=501) you create a relative timer that fires |
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301 | after three seconds. |
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302 | |
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303 | With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will |
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304 | both return C<501>, because that is the current time, and the timer will |
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305 | be scheduled to fire at time=504 (C<501> + C<3>). |
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306 | |
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307 | With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current |
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308 | time), but C<< AnyEvent->now >> returns C<500>, as that is the time the |
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309 | last event processing phase started. With L<EV>, your timer gets scheduled |
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310 | to run at time=503 (C<500> + C<3>). |
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311 | |
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312 | In one sense, L<Event::Lib> is more exact, as it uses the current time |
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313 | regardless of any delays introduced by event processing. However, most |
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314 | callbacks do not expect large delays in processing, so this causes a |
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315 | higher drift (and a lot more system calls to get the current time). |
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316 | |
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317 | In another sense, L<EV> is more exact, as your timer will be scheduled at |
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318 | the same time, regardless of how long event processing actually took. |
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319 | |
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320 | In either case, if you care (and in most cases, you don't), then you |
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321 | can get whatever behaviour you want with any event loop, by taking the |
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322 | difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into |
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323 | account. |
|
|
324 | |
|
|
325 | =back |
|
|
326 | |
226 | =head2 SIGNAL WATCHERS |
327 | =head2 SIGNAL WATCHERS |
227 | |
328 | |
228 | You can watch for signals using a signal watcher, C<signal> is the signal |
329 | You can watch for signals using a signal watcher, C<signal> is the signal |
229 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
330 | I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl |
230 | be invoked whenever a signal occurs. |
331 | callback to be invoked whenever a signal occurs. |
231 | |
332 | |
|
|
333 | Although the callback might get passed parameters, their value and |
|
|
334 | presence is undefined and you cannot rely on them. Portable AnyEvent |
|
|
335 | callbacks cannot use arguments passed to signal watcher callbacks. |
|
|
336 | |
232 | Multiple signal occurances can be clumped together into one callback |
337 | Multiple signal occurrences can be clumped together into one callback |
233 | invocation, and callback invocation will be synchronous. synchronous means |
338 | invocation, and callback invocation will be synchronous. Synchronous means |
234 | that it might take a while until the signal gets handled by the process, |
339 | that it might take a while until the signal gets handled by the process, |
235 | but it is guarenteed not to interrupt any other callbacks. |
340 | but it is guaranteed not to interrupt any other callbacks. |
236 | |
341 | |
237 | The main advantage of using these watchers is that you can share a signal |
342 | The main advantage of using these watchers is that you can share a signal |
238 | between multiple watchers. |
343 | between multiple watchers. |
239 | |
344 | |
240 | This watcher might use C<%SIG>, so programs overwriting those signals |
345 | This watcher might use C<%SIG>, so programs overwriting those signals |
… | |
… | |
247 | =head2 CHILD PROCESS WATCHERS |
352 | =head2 CHILD PROCESS WATCHERS |
248 | |
353 | |
249 | You can also watch on a child process exit and catch its exit status. |
354 | You can also watch on a child process exit and catch its exit status. |
250 | |
355 | |
251 | The child process is specified by the C<pid> argument (if set to C<0>, it |
356 | The child process is specified by the C<pid> argument (if set to C<0>, it |
252 | watches for any child process exit). The watcher will trigger as often |
357 | watches for any child process exit). The watcher will triggered only when |
253 | as status change for the child are received. This works by installing a |
358 | the child process has finished and an exit status is available, not on |
254 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
359 | any trace events (stopped/continued). |
255 | and exit status (as returned by waitpid). |
|
|
256 | |
360 | |
257 | Example: wait for pid 1333 |
361 | The callback will be called with the pid and exit status (as returned by |
|
|
362 | waitpid), so unlike other watcher types, you I<can> rely on child watcher |
|
|
363 | callback arguments. |
258 | |
364 | |
|
|
365 | This watcher type works by installing a signal handler for C<SIGCHLD>, |
|
|
366 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
|
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367 | random child processes (waiting for specific child processes, e.g. inside |
|
|
368 | C<system>, is just fine). |
|
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369 | |
|
|
370 | There is a slight catch to child watchers, however: you usually start them |
|
|
371 | I<after> the child process was created, and this means the process could |
|
|
372 | have exited already (and no SIGCHLD will be sent anymore). |
|
|
373 | |
|
|
374 | Not all event models handle this correctly (POE doesn't), but even for |
|
|
375 | event models that I<do> handle this correctly, they usually need to be |
|
|
376 | loaded before the process exits (i.e. before you fork in the first place). |
|
|
377 | |
|
|
378 | This means you cannot create a child watcher as the very first thing in an |
|
|
379 | AnyEvent program, you I<have> to create at least one watcher before you |
|
|
380 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
|
|
381 | |
|
|
382 | Example: fork a process and wait for it |
|
|
383 | |
|
|
384 | my $done = AnyEvent->condvar; |
|
|
385 | |
|
|
386 | my $pid = fork or exit 5; |
|
|
387 | |
259 | my $w = AnyEvent->child ( |
388 | my $w = AnyEvent->child ( |
260 | pid => 1333, |
389 | pid => $pid, |
261 | cb => sub { |
390 | cb => sub { |
262 | my ($pid, $status) = @_; |
391 | my ($pid, $status) = @_; |
263 | warn "pid $pid exited with status $status"; |
392 | warn "pid $pid exited with status $status"; |
|
|
393 | $done->send; |
264 | }, |
394 | }, |
265 | ); |
395 | ); |
|
|
396 | |
|
|
397 | # do something else, then wait for process exit |
|
|
398 | $done->recv; |
266 | |
399 | |
267 | =head2 CONDITION VARIABLES |
400 | =head2 CONDITION VARIABLES |
268 | |
401 | |
|
|
402 | If you are familiar with some event loops you will know that all of them |
|
|
403 | require you to run some blocking "loop", "run" or similar function that |
|
|
404 | will actively watch for new events and call your callbacks. |
|
|
405 | |
|
|
406 | AnyEvent is different, it expects somebody else to run the event loop and |
|
|
407 | will only block when necessary (usually when told by the user). |
|
|
408 | |
|
|
409 | The instrument to do that is called a "condition variable", so called |
|
|
410 | because they represent a condition that must become true. |
|
|
411 | |
269 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
412 | Condition variables can be created by calling the C<< AnyEvent->condvar |
270 | method without any arguments. |
413 | >> method, usually without arguments. The only argument pair allowed is |
271 | |
414 | |
272 | A condition variable waits for a condition - precisely that the C<< |
415 | C<cb>, which specifies a callback to be called when the condition variable |
273 | ->broadcast >> method has been called. |
416 | becomes true, with the condition variable as the first argument (but not |
|
|
417 | the results). |
274 | |
418 | |
275 | They are very useful to signal that a condition has been fulfilled, for |
419 | After creation, the condition variable is "false" until it becomes "true" |
|
|
420 | by calling the C<send> method (or calling the condition variable as if it |
|
|
421 | were a callback, read about the caveats in the description for the C<< |
|
|
422 | ->send >> method). |
|
|
423 | |
|
|
424 | Condition variables are similar to callbacks, except that you can |
|
|
425 | optionally wait for them. They can also be called merge points - points |
|
|
426 | in time where multiple outstanding events have been processed. And yet |
|
|
427 | another way to call them is transactions - each condition variable can be |
|
|
428 | used to represent a transaction, which finishes at some point and delivers |
|
|
429 | a result. |
|
|
430 | |
|
|
431 | Condition variables are very useful to signal that something has finished, |
276 | example, if you write a module that does asynchronous http requests, |
432 | for example, if you write a module that does asynchronous http requests, |
277 | then a condition variable would be the ideal candidate to signal the |
433 | then a condition variable would be the ideal candidate to signal the |
278 | availability of results. |
434 | availability of results. The user can either act when the callback is |
|
|
435 | called or can synchronously C<< ->recv >> for the results. |
279 | |
436 | |
280 | You can also use condition variables to block your main program until |
437 | You can also use them to simulate traditional event loops - for example, |
281 | an event occurs - for example, you could C<< ->wait >> in your main |
438 | you can block your main program until an event occurs - for example, you |
282 | program until the user clicks the Quit button in your app, which would C<< |
439 | could C<< ->recv >> in your main program until the user clicks the Quit |
283 | ->broadcast >> the "quit" event. |
440 | button of your app, which would C<< ->send >> the "quit" event. |
284 | |
441 | |
285 | Note that condition variables recurse into the event loop - if you have |
442 | Note that condition variables recurse into the event loop - if you have |
286 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
443 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
287 | lose. Therefore, condition variables are good to export to your caller, but |
444 | lose. Therefore, condition variables are good to export to your caller, but |
288 | you should avoid making a blocking wait yourself, at least in callbacks, |
445 | you should avoid making a blocking wait yourself, at least in callbacks, |
289 | as this asks for trouble. |
446 | as this asks for trouble. |
290 | |
447 | |
291 | This object has two methods: |
448 | Condition variables are represented by hash refs in perl, and the keys |
|
|
449 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
|
|
450 | easy (it is often useful to build your own transaction class on top of |
|
|
451 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
|
|
452 | it's C<new> method in your own C<new> method. |
|
|
453 | |
|
|
454 | There are two "sides" to a condition variable - the "producer side" which |
|
|
455 | eventually calls C<< -> send >>, and the "consumer side", which waits |
|
|
456 | for the send to occur. |
|
|
457 | |
|
|
458 | Example: wait for a timer. |
|
|
459 | |
|
|
460 | # wait till the result is ready |
|
|
461 | my $result_ready = AnyEvent->condvar; |
|
|
462 | |
|
|
463 | # do something such as adding a timer |
|
|
464 | # or socket watcher the calls $result_ready->send |
|
|
465 | # when the "result" is ready. |
|
|
466 | # in this case, we simply use a timer: |
|
|
467 | my $w = AnyEvent->timer ( |
|
|
468 | after => 1, |
|
|
469 | cb => sub { $result_ready->send }, |
|
|
470 | ); |
|
|
471 | |
|
|
472 | # this "blocks" (while handling events) till the callback |
|
|
473 | # calls send |
|
|
474 | $result_ready->recv; |
|
|
475 | |
|
|
476 | Example: wait for a timer, but take advantage of the fact that |
|
|
477 | condition variables are also code references. |
|
|
478 | |
|
|
479 | my $done = AnyEvent->condvar; |
|
|
480 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
|
|
481 | $done->recv; |
|
|
482 | |
|
|
483 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
484 | callbacks. This is how you make a synchronous call, for example from |
|
|
485 | the main program: |
|
|
486 | |
|
|
487 | use AnyEvent::CouchDB; |
|
|
488 | |
|
|
489 | ... |
|
|
490 | |
|
|
491 | my @info = $couchdb->info->recv; |
|
|
492 | |
|
|
493 | And this is how you would just ste a callback to be called whenever the |
|
|
494 | results are available: |
|
|
495 | |
|
|
496 | $couchdb->info->cb (sub { |
|
|
497 | my @info = $_[0]->recv; |
|
|
498 | }); |
|
|
499 | |
|
|
500 | =head3 METHODS FOR PRODUCERS |
|
|
501 | |
|
|
502 | These methods should only be used by the producing side, i.e. the |
|
|
503 | code/module that eventually sends the signal. Note that it is also |
|
|
504 | the producer side which creates the condvar in most cases, but it isn't |
|
|
505 | uncommon for the consumer to create it as well. |
292 | |
506 | |
293 | =over 4 |
507 | =over 4 |
294 | |
508 | |
|
|
509 | =item $cv->send (...) |
|
|
510 | |
|
|
511 | Flag the condition as ready - a running C<< ->recv >> and all further |
|
|
512 | calls to C<recv> will (eventually) return after this method has been |
|
|
513 | called. If nobody is waiting the send will be remembered. |
|
|
514 | |
|
|
515 | If a callback has been set on the condition variable, it is called |
|
|
516 | immediately from within send. |
|
|
517 | |
|
|
518 | Any arguments passed to the C<send> call will be returned by all |
|
|
519 | future C<< ->recv >> calls. |
|
|
520 | |
|
|
521 | Condition variables are overloaded so one can call them directly |
|
|
522 | (as a code reference). Calling them directly is the same as calling |
|
|
523 | C<send>. Note, however, that many C-based event loops do not handle |
|
|
524 | overloading, so as tempting as it may be, passing a condition variable |
|
|
525 | instead of a callback does not work. Both the pure perl and EV loops |
|
|
526 | support overloading, however, as well as all functions that use perl to |
|
|
527 | invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for |
|
|
528 | example). |
|
|
529 | |
|
|
530 | =item $cv->croak ($error) |
|
|
531 | |
|
|
532 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
|
|
533 | C<Carp::croak> with the given error message/object/scalar. |
|
|
534 | |
|
|
535 | This can be used to signal any errors to the condition variable |
|
|
536 | user/consumer. |
|
|
537 | |
|
|
538 | =item $cv->begin ([group callback]) |
|
|
539 | |
295 | =item $cv->wait |
540 | =item $cv->end |
296 | |
541 | |
297 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
542 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
543 | |
|
|
544 | These two methods can be used to combine many transactions/events into |
|
|
545 | one. For example, a function that pings many hosts in parallel might want |
|
|
546 | to use a condition variable for the whole process. |
|
|
547 | |
|
|
548 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
549 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
550 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
551 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
552 | callback was set, C<send> will be called without any arguments. |
|
|
553 | |
|
|
554 | Let's clarify this with the ping example: |
|
|
555 | |
|
|
556 | my $cv = AnyEvent->condvar; |
|
|
557 | |
|
|
558 | my %result; |
|
|
559 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
560 | |
|
|
561 | for my $host (@list_of_hosts) { |
|
|
562 | $cv->begin; |
|
|
563 | ping_host_then_call_callback $host, sub { |
|
|
564 | $result{$host} = ...; |
|
|
565 | $cv->end; |
|
|
566 | }; |
|
|
567 | } |
|
|
568 | |
|
|
569 | $cv->end; |
|
|
570 | |
|
|
571 | This code fragment supposedly pings a number of hosts and calls |
|
|
572 | C<send> after results for all then have have been gathered - in any |
|
|
573 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
574 | each ping request and calls C<end> when it has received some result for |
|
|
575 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
576 | results arrive is not relevant. |
|
|
577 | |
|
|
578 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
579 | loop, which serves two important purposes: first, it sets the callback |
|
|
580 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
581 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
582 | doesn't execute once). |
|
|
583 | |
|
|
584 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
585 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
586 | is called at least once, and then, for each subrequest you start, call |
|
|
587 | C<begin> and for each subrequest you finish, call C<end>. |
|
|
588 | |
|
|
589 | =back |
|
|
590 | |
|
|
591 | =head3 METHODS FOR CONSUMERS |
|
|
592 | |
|
|
593 | These methods should only be used by the consuming side, i.e. the |
|
|
594 | code awaits the condition. |
|
|
595 | |
|
|
596 | =over 4 |
|
|
597 | |
|
|
598 | =item $cv->recv |
|
|
599 | |
|
|
600 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
298 | called on c<$cv>, while servicing other watchers normally. |
601 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
602 | normally. |
299 | |
603 | |
300 | You can only wait once on a condition - additional calls will return |
604 | You can only wait once on a condition - additional calls are valid but |
301 | immediately. |
605 | will return immediately. |
|
|
606 | |
|
|
607 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
608 | function will call C<croak>. |
|
|
609 | |
|
|
610 | In list context, all parameters passed to C<send> will be returned, |
|
|
611 | in scalar context only the first one will be returned. |
302 | |
612 | |
303 | Not all event models support a blocking wait - some die in that case |
613 | Not all event models support a blocking wait - some die in that case |
304 | (programs might want to do that to stay interactive), so I<if you are |
614 | (programs might want to do that to stay interactive), so I<if you are |
305 | using this from a module, never require a blocking wait>, but let the |
615 | using this from a module, never require a blocking wait>, but let the |
306 | caller decide whether the call will block or not (for example, by coupling |
616 | caller decide whether the call will block or not (for example, by coupling |
307 | condition variables with some kind of request results and supporting |
617 | condition variables with some kind of request results and supporting |
308 | callbacks so the caller knows that getting the result will not block, |
618 | callbacks so the caller knows that getting the result will not block, |
309 | while still suppporting blocking waits if the caller so desires). |
619 | while still supporting blocking waits if the caller so desires). |
310 | |
620 | |
311 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
621 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
312 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
622 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
313 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
623 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
314 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
624 | can supply. |
315 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
|
|
316 | from different coroutines, however). |
|
|
317 | |
625 | |
318 | =item $cv->broadcast |
626 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
627 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
628 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
629 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
630 | coroutine (one that doesn't run the event loop). |
319 | |
631 | |
320 | Flag the condition as ready - a running C<< ->wait >> and all further |
632 | You can ensure that C<< -recv >> never blocks by setting a callback and |
321 | calls to C<wait> will (eventually) return after this method has been |
633 | only calling C<< ->recv >> from within that callback (or at a later |
322 | called. If nobody is waiting the broadcast will be remembered.. |
634 | time). This will work even when the event loop does not support blocking |
|
|
635 | waits otherwise. |
|
|
636 | |
|
|
637 | =item $bool = $cv->ready |
|
|
638 | |
|
|
639 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
640 | C<croak> have been called. |
|
|
641 | |
|
|
642 | =item $cb = $cv->cb ($cb->($cv)) |
|
|
643 | |
|
|
644 | This is a mutator function that returns the callback set and optionally |
|
|
645 | replaces it before doing so. |
|
|
646 | |
|
|
647 | The callback will be called when the condition becomes "true", i.e. when |
|
|
648 | C<send> or C<croak> are called, with the only argument being the condition |
|
|
649 | variable itself. Calling C<recv> inside the callback or at any later time |
|
|
650 | is guaranteed not to block. |
323 | |
651 | |
324 | =back |
652 | =back |
325 | |
|
|
326 | Example: |
|
|
327 | |
|
|
328 | # wait till the result is ready |
|
|
329 | my $result_ready = AnyEvent->condvar; |
|
|
330 | |
|
|
331 | # do something such as adding a timer |
|
|
332 | # or socket watcher the calls $result_ready->broadcast |
|
|
333 | # when the "result" is ready. |
|
|
334 | # in this case, we simply use a timer: |
|
|
335 | my $w = AnyEvent->timer ( |
|
|
336 | after => 1, |
|
|
337 | cb => sub { $result_ready->broadcast }, |
|
|
338 | ); |
|
|
339 | |
|
|
340 | # this "blocks" (while handling events) till the watcher |
|
|
341 | # calls broadcast |
|
|
342 | $result_ready->wait; |
|
|
343 | |
653 | |
344 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
654 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
345 | |
655 | |
346 | =over 4 |
656 | =over 4 |
347 | |
657 | |
… | |
… | |
353 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
663 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
354 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
664 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
355 | |
665 | |
356 | The known classes so far are: |
666 | The known classes so far are: |
357 | |
667 | |
358 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
|
|
359 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
|
|
360 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
668 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
361 | AnyEvent::Impl::Event based on Event, second best choice. |
669 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
670 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
362 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
671 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
363 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
672 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
364 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
|
|
365 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
673 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
366 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
674 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
675 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
676 | |
|
|
677 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
678 | watching file handles. However, you can use WxWidgets through the |
|
|
679 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
680 | second, which was considered to be too horrible to even consider for |
|
|
681 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
682 | it's adaptor. |
|
|
683 | |
|
|
684 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
685 | autodetecting them. |
367 | |
686 | |
368 | =item AnyEvent::detect |
687 | =item AnyEvent::detect |
369 | |
688 | |
370 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
689 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
371 | if necessary. You should only call this function right before you would |
690 | if necessary. You should only call this function right before you would |
372 | have created an AnyEvent watcher anyway, that is, as late as possible at |
691 | have created an AnyEvent watcher anyway, that is, as late as possible at |
373 | runtime. |
692 | runtime. |
374 | |
693 | |
|
|
694 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
695 | |
|
|
696 | Arranges for the code block to be executed as soon as the event model is |
|
|
697 | autodetected (or immediately if this has already happened). |
|
|
698 | |
|
|
699 | If called in scalar or list context, then it creates and returns an object |
|
|
700 | that automatically removes the callback again when it is destroyed. See |
|
|
701 | L<Coro::BDB> for a case where this is useful. |
|
|
702 | |
|
|
703 | =item @AnyEvent::post_detect |
|
|
704 | |
|
|
705 | If there are any code references in this array (you can C<push> to it |
|
|
706 | before or after loading AnyEvent), then they will called directly after |
|
|
707 | the event loop has been chosen. |
|
|
708 | |
|
|
709 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
710 | if it contains a true value then the event loop has already been detected, |
|
|
711 | and the array will be ignored. |
|
|
712 | |
|
|
713 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
|
|
714 | |
375 | =back |
715 | =back |
376 | |
716 | |
377 | =head1 WHAT TO DO IN A MODULE |
717 | =head1 WHAT TO DO IN A MODULE |
378 | |
718 | |
379 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
719 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
… | |
… | |
382 | Be careful when you create watchers in the module body - AnyEvent will |
722 | Be careful when you create watchers in the module body - AnyEvent will |
383 | decide which event module to use as soon as the first method is called, so |
723 | decide which event module to use as soon as the first method is called, so |
384 | by calling AnyEvent in your module body you force the user of your module |
724 | by calling AnyEvent in your module body you force the user of your module |
385 | to load the event module first. |
725 | to load the event module first. |
386 | |
726 | |
387 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
727 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
388 | the C<< ->broadcast >> method has been called on it already. This is |
728 | the C<< ->send >> method has been called on it already. This is |
389 | because it will stall the whole program, and the whole point of using |
729 | because it will stall the whole program, and the whole point of using |
390 | events is to stay interactive. |
730 | events is to stay interactive. |
391 | |
731 | |
392 | It is fine, however, to call C<< ->wait >> when the user of your module |
732 | It is fine, however, to call C<< ->recv >> when the user of your module |
393 | requests it (i.e. if you create a http request object ad have a method |
733 | requests it (i.e. if you create a http request object ad have a method |
394 | called C<results> that returns the results, it should call C<< ->wait >> |
734 | called C<results> that returns the results, it should call C<< ->recv >> |
395 | freely, as the user of your module knows what she is doing. always). |
735 | freely, as the user of your module knows what she is doing. always). |
396 | |
736 | |
397 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
737 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
398 | |
738 | |
399 | There will always be a single main program - the only place that should |
739 | There will always be a single main program - the only place that should |
… | |
… | |
401 | |
741 | |
402 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
742 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
403 | do anything special (it does not need to be event-based) and let AnyEvent |
743 | do anything special (it does not need to be event-based) and let AnyEvent |
404 | decide which implementation to chose if some module relies on it. |
744 | decide which implementation to chose if some module relies on it. |
405 | |
745 | |
406 | If the main program relies on a specific event model. For example, in |
746 | If the main program relies on a specific event model - for example, in |
407 | Gtk2 programs you have to rely on the Glib module. You should load the |
747 | Gtk2 programs you have to rely on the Glib module - you should load the |
408 | event module before loading AnyEvent or any module that uses it: generally |
748 | event module before loading AnyEvent or any module that uses it: generally |
409 | speaking, you should load it as early as possible. The reason is that |
749 | speaking, you should load it as early as possible. The reason is that |
410 | modules might create watchers when they are loaded, and AnyEvent will |
750 | modules might create watchers when they are loaded, and AnyEvent will |
411 | decide on the event model to use as soon as it creates watchers, and it |
751 | decide on the event model to use as soon as it creates watchers, and it |
412 | might chose the wrong one unless you load the correct one yourself. |
752 | might chose the wrong one unless you load the correct one yourself. |
413 | |
753 | |
414 | You can chose to use a rather inefficient pure-perl implementation by |
754 | You can chose to use a pure-perl implementation by loading the |
415 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
755 | C<AnyEvent::Impl::Perl> module, which gives you similar behaviour |
416 | behaviour everywhere, but letting AnyEvent chose is generally better. |
756 | everywhere, but letting AnyEvent chose the model is generally better. |
|
|
757 | |
|
|
758 | =head2 MAINLOOP EMULATION |
|
|
759 | |
|
|
760 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
761 | only want to use AnyEvent), you do not want to run a specific event loop. |
|
|
762 | |
|
|
763 | In that case, you can use a condition variable like this: |
|
|
764 | |
|
|
765 | AnyEvent->condvar->recv; |
|
|
766 | |
|
|
767 | This has the effect of entering the event loop and looping forever. |
|
|
768 | |
|
|
769 | Note that usually your program has some exit condition, in which case |
|
|
770 | it is better to use the "traditional" approach of storing a condition |
|
|
771 | variable somewhere, waiting for it, and sending it when the program should |
|
|
772 | exit cleanly. |
|
|
773 | |
|
|
774 | |
|
|
775 | =head1 OTHER MODULES |
|
|
776 | |
|
|
777 | The following is a non-exhaustive list of additional modules that use |
|
|
778 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
779 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
780 | available via CPAN. |
|
|
781 | |
|
|
782 | =over 4 |
|
|
783 | |
|
|
784 | =item L<AnyEvent::Util> |
|
|
785 | |
|
|
786 | Contains various utility functions that replace often-used but blocking |
|
|
787 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
788 | |
|
|
789 | =item L<AnyEvent::Socket> |
|
|
790 | |
|
|
791 | Provides various utility functions for (internet protocol) sockets, |
|
|
792 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
793 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
794 | |
|
|
795 | =item L<AnyEvent::Handle> |
|
|
796 | |
|
|
797 | Provide read and write buffers, manages watchers for reads and writes, |
|
|
798 | supports raw and formatted I/O, I/O queued and fully transparent and |
|
|
799 | non-blocking SSL/TLS. |
|
|
800 | |
|
|
801 | =item L<AnyEvent::DNS> |
|
|
802 | |
|
|
803 | Provides rich asynchronous DNS resolver capabilities. |
|
|
804 | |
|
|
805 | =item L<AnyEvent::HTTP> |
|
|
806 | |
|
|
807 | A simple-to-use HTTP library that is capable of making a lot of concurrent |
|
|
808 | HTTP requests. |
|
|
809 | |
|
|
810 | =item L<AnyEvent::HTTPD> |
|
|
811 | |
|
|
812 | Provides a simple web application server framework. |
|
|
813 | |
|
|
814 | =item L<AnyEvent::FastPing> |
|
|
815 | |
|
|
816 | The fastest ping in the west. |
|
|
817 | |
|
|
818 | =item L<AnyEvent::DBI> |
|
|
819 | |
|
|
820 | Executes L<DBI> requests asynchronously in a proxy process. |
|
|
821 | |
|
|
822 | =item L<AnyEvent::AIO> |
|
|
823 | |
|
|
824 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
825 | programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent |
|
|
826 | together. |
|
|
827 | |
|
|
828 | =item L<AnyEvent::BDB> |
|
|
829 | |
|
|
830 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses |
|
|
831 | L<BDB> and AnyEvent together. |
|
|
832 | |
|
|
833 | =item L<AnyEvent::GPSD> |
|
|
834 | |
|
|
835 | A non-blocking interface to gpsd, a daemon delivering GPS information. |
|
|
836 | |
|
|
837 | =item L<AnyEvent::IGS> |
|
|
838 | |
|
|
839 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
840 | L<App::IGS>). |
|
|
841 | |
|
|
842 | =item L<AnyEvent::IRC> |
|
|
843 | |
|
|
844 | AnyEvent based IRC client module family (replacing the older Net::IRC3). |
|
|
845 | |
|
|
846 | =item L<Net::XMPP2> |
|
|
847 | |
|
|
848 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
849 | |
|
|
850 | =item L<Net::FCP> |
|
|
851 | |
|
|
852 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
853 | of AnyEvent. |
|
|
854 | |
|
|
855 | =item L<Event::ExecFlow> |
|
|
856 | |
|
|
857 | High level API for event-based execution flow control. |
|
|
858 | |
|
|
859 | =item L<Coro> |
|
|
860 | |
|
|
861 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
862 | |
|
|
863 | =item L<IO::Lambda> |
|
|
864 | |
|
|
865 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
866 | |
|
|
867 | =back |
417 | |
868 | |
418 | =cut |
869 | =cut |
419 | |
870 | |
420 | package AnyEvent; |
871 | package AnyEvent; |
421 | |
872 | |
422 | no warnings; |
873 | no warnings; |
423 | use strict; |
874 | use strict qw(vars subs); |
424 | |
875 | |
425 | use Carp; |
876 | use Carp; |
426 | |
877 | |
427 | our $VERSION = '3.2'; |
878 | our $VERSION = 4.35; |
428 | our $MODEL; |
879 | our $MODEL; |
429 | |
880 | |
430 | our $AUTOLOAD; |
881 | our $AUTOLOAD; |
431 | our @ISA; |
882 | our @ISA; |
432 | |
883 | |
|
|
884 | our @REGISTRY; |
|
|
885 | |
|
|
886 | our $WIN32; |
|
|
887 | |
|
|
888 | BEGIN { |
|
|
889 | my $win32 = ! ! ($^O =~ /mswin32/i); |
|
|
890 | eval "sub WIN32(){ $win32 }"; |
|
|
891 | } |
|
|
892 | |
433 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
893 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
434 | |
894 | |
435 | our @REGISTRY; |
895 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
|
|
896 | |
|
|
897 | { |
|
|
898 | my $idx; |
|
|
899 | $PROTOCOL{$_} = ++$idx |
|
|
900 | for reverse split /\s*,\s*/, |
|
|
901 | $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
902 | } |
436 | |
903 | |
437 | my @models = ( |
904 | my @models = ( |
438 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
439 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
440 | [EV:: => AnyEvent::Impl::EV::], |
905 | [EV:: => AnyEvent::Impl::EV::], |
441 | [Event:: => AnyEvent::Impl::Event::], |
906 | [Event:: => AnyEvent::Impl::Event::], |
442 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
443 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
444 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
907 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
908 | # everything below here will not be autoprobed |
|
|
909 | # as the pureperl backend should work everywhere |
|
|
910 | # and is usually faster |
|
|
911 | [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles |
|
|
912 | [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers |
|
|
913 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
914 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
915 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
|
|
916 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
917 | [Prima:: => AnyEvent::Impl::POE::], |
445 | ); |
918 | ); |
446 | my @models_detect = ( |
|
|
447 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
448 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
449 | ); |
|
|
450 | |
919 | |
451 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
920 | our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); |
|
|
921 | |
|
|
922 | our @post_detect; |
|
|
923 | |
|
|
924 | sub post_detect(&) { |
|
|
925 | my ($cb) = @_; |
|
|
926 | |
|
|
927 | if ($MODEL) { |
|
|
928 | $cb->(); |
|
|
929 | |
|
|
930 | 1 |
|
|
931 | } else { |
|
|
932 | push @post_detect, $cb; |
|
|
933 | |
|
|
934 | defined wantarray |
|
|
935 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
936 | : () |
|
|
937 | } |
|
|
938 | } |
|
|
939 | |
|
|
940 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
941 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
942 | } |
452 | |
943 | |
453 | sub detect() { |
944 | sub detect() { |
454 | unless ($MODEL) { |
945 | unless ($MODEL) { |
455 | no strict 'refs'; |
946 | no strict 'refs'; |
|
|
947 | local $SIG{__DIE__}; |
456 | |
948 | |
457 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
949 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
458 | my $model = "AnyEvent::Impl::$1"; |
950 | my $model = "AnyEvent::Impl::$1"; |
459 | if (eval "require $model") { |
951 | if (eval "require $model") { |
460 | $MODEL = $model; |
952 | $MODEL = $model; |
461 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
953 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
954 | } else { |
|
|
955 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
462 | } |
956 | } |
463 | } |
957 | } |
464 | |
958 | |
465 | # check for already loaded models |
959 | # check for already loaded models |
466 | unless ($MODEL) { |
960 | unless ($MODEL) { |
467 | for (@REGISTRY, @models, @models_detect) { |
961 | for (@REGISTRY, @models) { |
468 | my ($package, $model) = @$_; |
962 | my ($package, $model) = @$_; |
469 | if (${"$package\::VERSION"} > 0) { |
963 | if (${"$package\::VERSION"} > 0) { |
470 | if (eval "require $model") { |
964 | if (eval "require $model") { |
471 | $MODEL = $model; |
965 | $MODEL = $model; |
472 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
966 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
… | |
… | |
488 | last; |
982 | last; |
489 | } |
983 | } |
490 | } |
984 | } |
491 | |
985 | |
492 | $MODEL |
986 | $MODEL |
493 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; |
987 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
494 | } |
988 | } |
495 | } |
989 | } |
496 | |
990 | |
|
|
991 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
|
|
992 | |
497 | unshift @ISA, $MODEL; |
993 | unshift @ISA, $MODEL; |
498 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
994 | |
|
|
995 | require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT}; |
|
|
996 | |
|
|
997 | (shift @post_detect)->() while @post_detect; |
499 | } |
998 | } |
500 | |
999 | |
501 | $MODEL |
1000 | $MODEL |
502 | } |
1001 | } |
503 | |
1002 | |
… | |
… | |
511 | |
1010 | |
512 | my $class = shift; |
1011 | my $class = shift; |
513 | $class->$func (@_); |
1012 | $class->$func (@_); |
514 | } |
1013 | } |
515 | |
1014 | |
|
|
1015 | # utility function to dup a filehandle. this is used by many backends |
|
|
1016 | # to support binding more than one watcher per filehandle (they usually |
|
|
1017 | # allow only one watcher per fd, so we dup it to get a different one). |
|
|
1018 | sub _dupfh($$$$) { |
|
|
1019 | my ($poll, $fh, $r, $w) = @_; |
|
|
1020 | |
|
|
1021 | # cygwin requires the fh mode to be matching, unix doesn't |
|
|
1022 | my ($rw, $mode) = $poll eq "r" ? ($r, "<") |
|
|
1023 | : $poll eq "w" ? ($w, ">") |
|
|
1024 | : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'"; |
|
|
1025 | |
|
|
1026 | open my $fh2, "$mode&" . fileno $fh |
|
|
1027 | or die "cannot dup() filehandle: $!"; |
|
|
1028 | |
|
|
1029 | # we assume CLOEXEC is already set by perl in all important cases |
|
|
1030 | |
|
|
1031 | ($fh2, $rw) |
|
|
1032 | } |
|
|
1033 | |
516 | package AnyEvent::Base; |
1034 | package AnyEvent::Base; |
517 | |
1035 | |
|
|
1036 | # default implementation for now and time |
|
|
1037 | |
|
|
1038 | BEGIN { |
|
|
1039 | if (eval "use Time::HiRes (); time (); 1") { |
|
|
1040 | *_time = \&Time::HiRes::time; |
|
|
1041 | # if (eval "use POSIX (); (POSIX::times())... |
|
|
1042 | } else { |
|
|
1043 | *_time = sub { time }; # epic fail |
|
|
1044 | } |
|
|
1045 | } |
|
|
1046 | |
|
|
1047 | sub time { _time } |
|
|
1048 | sub now { _time } |
|
|
1049 | |
518 | # default implementation for ->condvar, ->wait, ->broadcast |
1050 | # default implementation for ->condvar |
519 | |
1051 | |
520 | sub condvar { |
1052 | sub condvar { |
521 | bless \my $flag, "AnyEvent::Base::CondVar" |
1053 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
522 | } |
|
|
523 | |
|
|
524 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
525 | ${$_[0]}++; |
|
|
526 | } |
|
|
527 | |
|
|
528 | sub AnyEvent::Base::CondVar::wait { |
|
|
529 | AnyEvent->one_event while !${$_[0]}; |
|
|
530 | } |
1054 | } |
531 | |
1055 | |
532 | # default implementation for ->signal |
1056 | # default implementation for ->signal |
533 | |
1057 | |
534 | our %SIG_CB; |
1058 | our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); |
|
|
1059 | |
|
|
1060 | sub _signal_exec { |
|
|
1061 | sysread $SIGPIPE_R, my $dummy, 4; |
|
|
1062 | |
|
|
1063 | while (%SIG_EV) { |
|
|
1064 | for (keys %SIG_EV) { |
|
|
1065 | delete $SIG_EV{$_}; |
|
|
1066 | $_->() for values %{ $SIG_CB{$_} || {} }; |
|
|
1067 | } |
|
|
1068 | } |
|
|
1069 | } |
535 | |
1070 | |
536 | sub signal { |
1071 | sub signal { |
537 | my (undef, %arg) = @_; |
1072 | my (undef, %arg) = @_; |
538 | |
1073 | |
|
|
1074 | unless ($SIGPIPE_R) { |
|
|
1075 | require Fcntl; |
|
|
1076 | |
|
|
1077 | if (AnyEvent::WIN32) { |
|
|
1078 | require AnyEvent::Util; |
|
|
1079 | |
|
|
1080 | ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe (); |
|
|
1081 | AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R; |
|
|
1082 | AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case |
|
|
1083 | } else { |
|
|
1084 | pipe $SIGPIPE_R, $SIGPIPE_W; |
|
|
1085 | fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R; |
|
|
1086 | fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case |
|
|
1087 | } |
|
|
1088 | |
|
|
1089 | $SIGPIPE_R |
|
|
1090 | or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; |
|
|
1091 | |
|
|
1092 | fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; |
|
|
1093 | fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; |
|
|
1094 | |
|
|
1095 | $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec); |
|
|
1096 | } |
|
|
1097 | |
539 | my $signal = uc $arg{signal} |
1098 | my $signal = uc $arg{signal} |
540 | or Carp::croak "required option 'signal' is missing"; |
1099 | or Carp::croak "required option 'signal' is missing"; |
541 | |
1100 | |
542 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
1101 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
543 | $SIG{$signal} ||= sub { |
1102 | $SIG{$signal} ||= sub { |
544 | $_->() for values %{ $SIG_CB{$signal} || {} }; |
1103 | syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV; |
|
|
1104 | undef $SIG_EV{$signal}; |
545 | }; |
1105 | }; |
546 | |
1106 | |
547 | bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
1107 | bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
548 | } |
1108 | } |
549 | |
1109 | |
550 | sub AnyEvent::Base::Signal::DESTROY { |
1110 | sub AnyEvent::Base::Signal::DESTROY { |
551 | my ($signal, $cb) = @{$_[0]}; |
1111 | my ($signal, $cb) = @{$_[0]}; |
552 | |
1112 | |
553 | delete $SIG_CB{$signal}{$cb}; |
1113 | delete $SIG_CB{$signal}{$cb}; |
554 | |
1114 | |
555 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
1115 | delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; |
556 | } |
1116 | } |
557 | |
1117 | |
558 | # default implementation for ->child |
1118 | # default implementation for ->child |
559 | |
1119 | |
560 | our %PID_CB; |
1120 | our %PID_CB; |
… | |
… | |
587 | or Carp::croak "required option 'pid' is missing"; |
1147 | or Carp::croak "required option 'pid' is missing"; |
588 | |
1148 | |
589 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
1149 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
590 | |
1150 | |
591 | unless ($WNOHANG) { |
1151 | unless ($WNOHANG) { |
592 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
1152 | $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; |
593 | } |
1153 | } |
594 | |
1154 | |
595 | unless ($CHLD_W) { |
1155 | unless ($CHLD_W) { |
596 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
1156 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
597 | # child could be a zombie already, so make at least one round |
1157 | # child could be a zombie already, so make at least one round |
… | |
… | |
607 | delete $PID_CB{$pid}{$cb}; |
1167 | delete $PID_CB{$pid}{$cb}; |
608 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
1168 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
609 | |
1169 | |
610 | undef $CHLD_W unless keys %PID_CB; |
1170 | undef $CHLD_W unless keys %PID_CB; |
611 | } |
1171 | } |
|
|
1172 | |
|
|
1173 | package AnyEvent::CondVar; |
|
|
1174 | |
|
|
1175 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
1176 | |
|
|
1177 | package AnyEvent::CondVar::Base; |
|
|
1178 | |
|
|
1179 | use overload |
|
|
1180 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
1181 | fallback => 1; |
|
|
1182 | |
|
|
1183 | sub _send { |
|
|
1184 | # nop |
|
|
1185 | } |
|
|
1186 | |
|
|
1187 | sub send { |
|
|
1188 | my $cv = shift; |
|
|
1189 | $cv->{_ae_sent} = [@_]; |
|
|
1190 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
1191 | $cv->_send; |
|
|
1192 | } |
|
|
1193 | |
|
|
1194 | sub croak { |
|
|
1195 | $_[0]{_ae_croak} = $_[1]; |
|
|
1196 | $_[0]->send; |
|
|
1197 | } |
|
|
1198 | |
|
|
1199 | sub ready { |
|
|
1200 | $_[0]{_ae_sent} |
|
|
1201 | } |
|
|
1202 | |
|
|
1203 | sub _wait { |
|
|
1204 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
1205 | } |
|
|
1206 | |
|
|
1207 | sub recv { |
|
|
1208 | $_[0]->_wait; |
|
|
1209 | |
|
|
1210 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
1211 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
1212 | } |
|
|
1213 | |
|
|
1214 | sub cb { |
|
|
1215 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
1216 | $_[0]{_ae_cb} |
|
|
1217 | } |
|
|
1218 | |
|
|
1219 | sub begin { |
|
|
1220 | ++$_[0]{_ae_counter}; |
|
|
1221 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
1222 | } |
|
|
1223 | |
|
|
1224 | sub end { |
|
|
1225 | return if --$_[0]{_ae_counter}; |
|
|
1226 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
1227 | } |
|
|
1228 | |
|
|
1229 | # undocumented/compatibility with pre-3.4 |
|
|
1230 | *broadcast = \&send; |
|
|
1231 | *wait = \&_wait; |
|
|
1232 | |
|
|
1233 | =head1 ERROR AND EXCEPTION HANDLING |
|
|
1234 | |
|
|
1235 | In general, AnyEvent does not do any error handling - it relies on the |
|
|
1236 | caller to do that if required. The L<AnyEvent::Strict> module (see also |
|
|
1237 | the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict |
|
|
1238 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
1239 | development. |
|
|
1240 | |
|
|
1241 | As for exception handling (i.e. runtime errors and exceptions thrown while |
|
|
1242 | executing a callback), this is not only highly event-loop specific, but |
|
|
1243 | also not in any way wrapped by this module, as this is the job of the main |
|
|
1244 | program. |
|
|
1245 | |
|
|
1246 | The pure perl event loop simply re-throws the exception (usually |
|
|
1247 | within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<< |
|
|
1248 | $Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and |
|
|
1249 | so on. |
|
|
1250 | |
|
|
1251 | =head1 ENVIRONMENT VARIABLES |
|
|
1252 | |
|
|
1253 | The following environment variables are used by this module or its |
|
|
1254 | submodules: |
|
|
1255 | |
|
|
1256 | =over 4 |
|
|
1257 | |
|
|
1258 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1259 | |
|
|
1260 | By default, AnyEvent will be completely silent except in fatal |
|
|
1261 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1262 | talkative. |
|
|
1263 | |
|
|
1264 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1265 | conditions, such as not being able to load the event model specified by |
|
|
1266 | C<PERL_ANYEVENT_MODEL>. |
|
|
1267 | |
|
|
1268 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1269 | model it chooses. |
|
|
1270 | |
|
|
1271 | =item C<PERL_ANYEVENT_STRICT> |
|
|
1272 | |
|
|
1273 | AnyEvent does not do much argument checking by default, as thorough |
|
|
1274 | argument checking is very costly. Setting this variable to a true value |
|
|
1275 | will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly |
|
|
1276 | check the arguments passed to most method calls. If it finds any problems |
|
|
1277 | it will croak. |
|
|
1278 | |
|
|
1279 | In other words, enables "strict" mode. |
|
|
1280 | |
|
|
1281 | Unlike C<use strict>, it is definitely recommended ot keep it off in |
|
|
1282 | production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while |
|
|
1283 | developing programs can be very useful, however. |
|
|
1284 | |
|
|
1285 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1286 | |
|
|
1287 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1288 | auto detection and -probing kicks in. It must be a string consisting |
|
|
1289 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1290 | and the resulting module name is loaded and if the load was successful, |
|
|
1291 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1292 | auto detection and -probing. |
|
|
1293 | |
|
|
1294 | This functionality might change in future versions. |
|
|
1295 | |
|
|
1296 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1297 | could start your program like this: |
|
|
1298 | |
|
|
1299 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1300 | |
|
|
1301 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1302 | |
|
|
1303 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1304 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1305 | of auto probing). |
|
|
1306 | |
|
|
1307 | Must be set to a comma-separated list of protocols or address families, |
|
|
1308 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1309 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1310 | list. |
|
|
1311 | |
|
|
1312 | This variable can effectively be used for denial-of-service attacks |
|
|
1313 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1314 | small, as the program has to handle conenction and other failures anyways. |
|
|
1315 | |
|
|
1316 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1317 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1318 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1319 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1320 | IPv6, but prefer IPv6 over IPv4. |
|
|
1321 | |
|
|
1322 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1323 | |
|
|
1324 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1325 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1326 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1327 | default. |
|
|
1328 | |
|
|
1329 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1330 | EDNS0 in its DNS requests. |
|
|
1331 | |
|
|
1332 | =item C<PERL_ANYEVENT_MAX_FORKS> |
|
|
1333 | |
|
|
1334 | The maximum number of child processes that C<AnyEvent::Util::fork_call> |
|
|
1335 | will create in parallel. |
|
|
1336 | |
|
|
1337 | =back |
612 | |
1338 | |
613 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1339 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
614 | |
1340 | |
615 | This is an advanced topic that you do not normally need to use AnyEvent in |
1341 | This is an advanced topic that you do not normally need to use AnyEvent in |
616 | a module. This section is only of use to event loop authors who want to |
1342 | a module. This section is only of use to event loop authors who want to |
… | |
… | |
651 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
1377 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
652 | condition variables: code blocking while waiting for a condition will |
1378 | condition variables: code blocking while waiting for a condition will |
653 | C<die>. This still works with most modules/usages, and blocking calls must |
1379 | C<die>. This still works with most modules/usages, and blocking calls must |
654 | not be done in an interactive application, so it makes sense. |
1380 | not be done in an interactive application, so it makes sense. |
655 | |
1381 | |
656 | =head1 ENVIRONMENT VARIABLES |
|
|
657 | |
|
|
658 | The following environment variables are used by this module: |
|
|
659 | |
|
|
660 | =over 4 |
|
|
661 | |
|
|
662 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
663 | |
|
|
664 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
665 | model it chooses. |
|
|
666 | |
|
|
667 | =item C<PERL_ANYEVENT_MODEL> |
|
|
668 | |
|
|
669 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
670 | autodetection and -probing kicks in. It must be a string consisting |
|
|
671 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
672 | and the resulting module name is loaded and if the load was successful, |
|
|
673 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
674 | autodetection and -probing. |
|
|
675 | |
|
|
676 | This functionality might change in future versions. |
|
|
677 | |
|
|
678 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
679 | could start your program like this: |
|
|
680 | |
|
|
681 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
682 | |
|
|
683 | =back |
|
|
684 | |
|
|
685 | =head1 EXAMPLE PROGRAM |
1382 | =head1 EXAMPLE PROGRAM |
686 | |
1383 | |
687 | The following program uses an IO watcher to read data from STDIN, a timer |
1384 | The following program uses an I/O watcher to read data from STDIN, a timer |
688 | to display a message once per second, and a condition variable to quit the |
1385 | to display a message once per second, and a condition variable to quit the |
689 | program when the user enters quit: |
1386 | program when the user enters quit: |
690 | |
1387 | |
691 | use AnyEvent; |
1388 | use AnyEvent; |
692 | |
1389 | |
… | |
… | |
697 | poll => 'r', |
1394 | poll => 'r', |
698 | cb => sub { |
1395 | cb => sub { |
699 | warn "io event <$_[0]>\n"; # will always output <r> |
1396 | warn "io event <$_[0]>\n"; # will always output <r> |
700 | chomp (my $input = <STDIN>); # read a line |
1397 | chomp (my $input = <STDIN>); # read a line |
701 | warn "read: $input\n"; # output what has been read |
1398 | warn "read: $input\n"; # output what has been read |
702 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1399 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
703 | }, |
1400 | }, |
704 | ); |
1401 | ); |
705 | |
1402 | |
706 | my $time_watcher; # can only be used once |
1403 | my $time_watcher; # can only be used once |
707 | |
1404 | |
… | |
… | |
712 | }); |
1409 | }); |
713 | } |
1410 | } |
714 | |
1411 | |
715 | new_timer; # create first timer |
1412 | new_timer; # create first timer |
716 | |
1413 | |
717 | $cv->wait; # wait until user enters /^q/i |
1414 | $cv->recv; # wait until user enters /^q/i |
718 | |
1415 | |
719 | =head1 REAL-WORLD EXAMPLE |
1416 | =head1 REAL-WORLD EXAMPLE |
720 | |
1417 | |
721 | Consider the L<Net::FCP> module. It features (among others) the following |
1418 | Consider the L<Net::FCP> module. It features (among others) the following |
722 | API calls, which are to freenet what HTTP GET requests are to http: |
1419 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
772 | syswrite $txn->{fh}, $txn->{request} |
1469 | syswrite $txn->{fh}, $txn->{request} |
773 | or die "connection or write error"; |
1470 | or die "connection or write error"; |
774 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1471 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
775 | |
1472 | |
776 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1473 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
777 | result and signals any possible waiters that the request ahs finished: |
1474 | result and signals any possible waiters that the request has finished: |
778 | |
1475 | |
779 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1476 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
780 | |
1477 | |
781 | if (end-of-file or data complete) { |
1478 | if (end-of-file or data complete) { |
782 | $txn->{result} = $txn->{buf}; |
1479 | $txn->{result} = $txn->{buf}; |
783 | $txn->{finished}->broadcast; |
1480 | $txn->{finished}->send; |
784 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1481 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
785 | } |
1482 | } |
786 | |
1483 | |
787 | The C<result> method, finally, just waits for the finished signal (if the |
1484 | The C<result> method, finally, just waits for the finished signal (if the |
788 | request was already finished, it doesn't wait, of course, and returns the |
1485 | request was already finished, it doesn't wait, of course, and returns the |
789 | data: |
1486 | data: |
790 | |
1487 | |
791 | $txn->{finished}->wait; |
1488 | $txn->{finished}->recv; |
792 | return $txn->{result}; |
1489 | return $txn->{result}; |
793 | |
1490 | |
794 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1491 | The actual code goes further and collects all errors (C<die>s, exceptions) |
795 | that occured during request processing. The C<result> method detects |
1492 | that occurred during request processing. The C<result> method detects |
796 | whether an exception as thrown (it is stored inside the $txn object) |
1493 | whether an exception as thrown (it is stored inside the $txn object) |
797 | and just throws the exception, which means connection errors and other |
1494 | and just throws the exception, which means connection errors and other |
798 | problems get reported tot he code that tries to use the result, not in a |
1495 | problems get reported tot he code that tries to use the result, not in a |
799 | random callback. |
1496 | random callback. |
800 | |
1497 | |
… | |
… | |
831 | |
1528 | |
832 | my $quit = AnyEvent->condvar; |
1529 | my $quit = AnyEvent->condvar; |
833 | |
1530 | |
834 | $fcp->txn_client_get ($url)->cb (sub { |
1531 | $fcp->txn_client_get ($url)->cb (sub { |
835 | ... |
1532 | ... |
836 | $quit->broadcast; |
1533 | $quit->send; |
837 | }); |
1534 | }); |
838 | |
1535 | |
839 | $quit->wait; |
1536 | $quit->recv; |
|
|
1537 | |
|
|
1538 | |
|
|
1539 | =head1 BENCHMARKS |
|
|
1540 | |
|
|
1541 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1542 | over the event loops themselves and to give you an impression of the speed |
|
|
1543 | of various event loops I prepared some benchmarks. |
|
|
1544 | |
|
|
1545 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1546 | |
|
|
1547 | Here is a benchmark of various supported event models used natively and |
|
|
1548 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1549 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1550 | which it is), lets them fire exactly once and destroys them again. |
|
|
1551 | |
|
|
1552 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1553 | distribution. |
|
|
1554 | |
|
|
1555 | =head3 Explanation of the columns |
|
|
1556 | |
|
|
1557 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1558 | different event models feature vastly different performances, each event |
|
|
1559 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1560 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1561 | would probably take thousands of years if asked to process the same number |
|
|
1562 | of watchers as EV in this benchmark. |
|
|
1563 | |
|
|
1564 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1565 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1566 | and Perl-based overheads. |
|
|
1567 | |
|
|
1568 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1569 | takes to create a single watcher. The callback is a closure shared between |
|
|
1570 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1571 | and memory usage is not included in the figures. |
|
|
1572 | |
|
|
1573 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1574 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1575 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1576 | signal the end of this phase. |
|
|
1577 | |
|
|
1578 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1579 | watcher. |
|
|
1580 | |
|
|
1581 | =head3 Results |
|
|
1582 | |
|
|
1583 | name watchers bytes create invoke destroy comment |
|
|
1584 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
|
|
1585 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
|
|
1586 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
|
|
1587 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
|
|
1588 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
|
|
1589 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1590 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
|
|
1591 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
|
|
1592 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
|
|
1593 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
|
|
1594 | |
|
|
1595 | =head3 Discussion |
|
|
1596 | |
|
|
1597 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1598 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1599 | can never compete with an event loop that uses epoll when the number of |
|
|
1600 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1601 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1602 | boost. |
|
|
1603 | |
|
|
1604 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1605 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1606 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1607 | higher number of watchers at a disadvantage. |
|
|
1608 | |
|
|
1609 | To put the range of results into perspective, consider that on the |
|
|
1610 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1611 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1612 | cycles with POE. |
|
|
1613 | |
|
|
1614 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1615 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1616 | far less memory than any other event loop and is still faster than Event |
|
|
1617 | natively. |
|
|
1618 | |
|
|
1619 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1620 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1621 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1622 | adds very little overhead in itself. Like any select-based backend its |
|
|
1623 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1624 | them active), of course, but this was not subject of this benchmark. |
|
|
1625 | |
|
|
1626 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1627 | cost, but overall scores in on the third place. |
|
|
1628 | |
|
|
1629 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1630 | faster callback invocation and overall ends up in the same class as |
|
|
1631 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1632 | watchers increases the processing time by more than a factor of four, |
|
|
1633 | making it completely unusable when using larger numbers of watchers |
|
|
1634 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1635 | inefficiencies of C<poll> do not account for this). |
|
|
1636 | |
|
|
1637 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1638 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1639 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1640 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1641 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1642 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1643 | above). |
|
|
1644 | |
|
|
1645 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1646 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1647 | be tested because it wasn't working) shows abysmal performance and |
|
|
1648 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1649 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1650 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1651 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1652 | implementation. |
|
|
1653 | |
|
|
1654 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1655 | for the performance issues, though, as session creation overhead is |
|
|
1656 | small compared to execution of the state machine, which is coded pretty |
|
|
1657 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1658 | using multiple sessions is not a good approach, especially regarding |
|
|
1659 | memory usage, even the author of POE could not come up with a faster |
|
|
1660 | design). |
|
|
1661 | |
|
|
1662 | =head3 Summary |
|
|
1663 | |
|
|
1664 | =over 4 |
|
|
1665 | |
|
|
1666 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1667 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1668 | performance with or without AnyEvent. |
|
|
1669 | |
|
|
1670 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1671 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1672 | adds AnyEvent significant overhead. |
|
|
1673 | |
|
|
1674 | =item * You should avoid POE like the plague if you want performance or |
|
|
1675 | reasonable memory usage. |
|
|
1676 | |
|
|
1677 | =back |
|
|
1678 | |
|
|
1679 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1680 | |
|
|
1681 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1682 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1683 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1684 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1685 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1686 | |
|
|
1687 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1688 | are active at any one point (so there is a constant number of active |
|
|
1689 | fds for each loop iteration, but which fds these are is random). The |
|
|
1690 | timeout is reset each time something is read because that reflects how |
|
|
1691 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1692 | |
|
|
1693 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1694 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1695 | connections, most of which are idle at any one point in time. |
|
|
1696 | |
|
|
1697 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1698 | distribution. |
|
|
1699 | |
|
|
1700 | =head3 Explanation of the columns |
|
|
1701 | |
|
|
1702 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1703 | each server has a read and write socket end). |
|
|
1704 | |
|
|
1705 | I<create> is the time it takes to create a socket pair (which is |
|
|
1706 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1707 | |
|
|
1708 | I<request>, the most important value, is the time it takes to handle a |
|
|
1709 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1710 | it to another server. This includes deleting the old timeout and creating |
|
|
1711 | a new one that moves the timeout into the future. |
|
|
1712 | |
|
|
1713 | =head3 Results |
|
|
1714 | |
|
|
1715 | name sockets create request |
|
|
1716 | EV 20000 69.01 11.16 |
|
|
1717 | Perl 20000 73.32 35.87 |
|
|
1718 | Event 20000 212.62 257.32 |
|
|
1719 | Glib 20000 651.16 1896.30 |
|
|
1720 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1721 | |
|
|
1722 | =head3 Discussion |
|
|
1723 | |
|
|
1724 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1725 | particular event loop. |
|
|
1726 | |
|
|
1727 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1728 | is relatively high, though. |
|
|
1729 | |
|
|
1730 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1731 | loops Event and Glib. |
|
|
1732 | |
|
|
1733 | Event suffers from high setup time as well (look at its code and you will |
|
|
1734 | understand why). Callback invocation also has a high overhead compared to |
|
|
1735 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1736 | uses select or poll in basically all documented configurations. |
|
|
1737 | |
|
|
1738 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1739 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1740 | |
|
|
1741 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1742 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1743 | it uses a C-based event loop in this case. |
|
|
1744 | |
|
|
1745 | =head3 Summary |
|
|
1746 | |
|
|
1747 | =over 4 |
|
|
1748 | |
|
|
1749 | =item * The pure perl implementation performs extremely well. |
|
|
1750 | |
|
|
1751 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1752 | |
|
|
1753 | =back |
|
|
1754 | |
|
|
1755 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1756 | |
|
|
1757 | While event loops should scale (and select-based ones do not...) even to |
|
|
1758 | large servers, most programs we (or I :) actually write have only a few |
|
|
1759 | I/O watchers. |
|
|
1760 | |
|
|
1761 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1762 | case, but it uses only eight "servers", of which three are active at any |
|
|
1763 | one time. This should reflect performance for a small server relatively |
|
|
1764 | well. |
|
|
1765 | |
|
|
1766 | The columns are identical to the previous table. |
|
|
1767 | |
|
|
1768 | =head3 Results |
|
|
1769 | |
|
|
1770 | name sockets create request |
|
|
1771 | EV 16 20.00 6.54 |
|
|
1772 | Perl 16 25.75 12.62 |
|
|
1773 | Event 16 81.27 35.86 |
|
|
1774 | Glib 16 32.63 15.48 |
|
|
1775 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1776 | |
|
|
1777 | =head3 Discussion |
|
|
1778 | |
|
|
1779 | The benchmark tries to test the performance of a typical small |
|
|
1780 | server. While knowing how various event loops perform is interesting, keep |
|
|
1781 | in mind that their overhead in this case is usually not as important, due |
|
|
1782 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1783 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1784 | them). |
|
|
1785 | |
|
|
1786 | EV is again fastest. |
|
|
1787 | |
|
|
1788 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1789 | loops Event and Glib, although the difference is too small to really |
|
|
1790 | matter. |
|
|
1791 | |
|
|
1792 | POE also performs much better in this case, but is is still far behind the |
|
|
1793 | others. |
|
|
1794 | |
|
|
1795 | =head3 Summary |
|
|
1796 | |
|
|
1797 | =over 4 |
|
|
1798 | |
|
|
1799 | =item * C-based event loops perform very well with small number of |
|
|
1800 | watchers, as the management overhead dominates. |
|
|
1801 | |
|
|
1802 | =back |
|
|
1803 | |
|
|
1804 | |
|
|
1805 | =head1 SIGNALS |
|
|
1806 | |
|
|
1807 | AnyEvent currently installs handlers for these signals: |
|
|
1808 | |
|
|
1809 | =over 4 |
|
|
1810 | |
|
|
1811 | =item SIGCHLD |
|
|
1812 | |
|
|
1813 | A handler for C<SIGCHLD> is installed by AnyEvent's child watcher |
|
|
1814 | emulation for event loops that do not support them natively. Also, some |
|
|
1815 | event loops install a similar handler. |
|
|
1816 | |
|
|
1817 | =item SIGPIPE |
|
|
1818 | |
|
|
1819 | A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> |
|
|
1820 | when AnyEvent gets loaded. |
|
|
1821 | |
|
|
1822 | The rationale for this is that AnyEvent users usually do not really depend |
|
|
1823 | on SIGPIPE delivery (which is purely an optimisation for shell use, or |
|
|
1824 | badly-written programs), but C<SIGPIPE> can cause spurious and rare |
|
|
1825 | program exits as a lot of people do not expect C<SIGPIPE> when writing to |
|
|
1826 | some random socket. |
|
|
1827 | |
|
|
1828 | The rationale for installing a no-op handler as opposed to ignoring it is |
|
|
1829 | that this way, the handler will be restored to defaults on exec. |
|
|
1830 | |
|
|
1831 | Feel free to install your own handler, or reset it to defaults. |
|
|
1832 | |
|
|
1833 | =back |
|
|
1834 | |
|
|
1835 | =cut |
|
|
1836 | |
|
|
1837 | $SIG{PIPE} = sub { } |
|
|
1838 | unless defined $SIG{PIPE}; |
|
|
1839 | |
840 | |
1840 | |
841 | =head1 FORK |
1841 | =head1 FORK |
842 | |
1842 | |
843 | Most event libraries are not fork-safe. The ones who are usually are |
1843 | Most event libraries are not fork-safe. The ones who are usually are |
844 | because they are so inefficient. Only L<EV> is fully fork-aware. |
1844 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1845 | calls. Only L<EV> is fully fork-aware. |
845 | |
1846 | |
846 | If you have to fork, you must either do so I<before> creating your first |
1847 | If you have to fork, you must either do so I<before> creating your first |
847 | watcher OR you must not use AnyEvent at all in the child. |
1848 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1849 | |
848 | |
1850 | |
849 | =head1 SECURITY CONSIDERATIONS |
1851 | =head1 SECURITY CONSIDERATIONS |
850 | |
1852 | |
851 | AnyEvent can be forced to load any event model via |
1853 | AnyEvent can be forced to load any event model via |
852 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
1854 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
… | |
… | |
856 | specified in the variable. |
1858 | specified in the variable. |
857 | |
1859 | |
858 | You can make AnyEvent completely ignore this variable by deleting it |
1860 | You can make AnyEvent completely ignore this variable by deleting it |
859 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
1861 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
860 | |
1862 | |
861 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1863 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
862 | |
1864 | |
863 | use AnyEvent; |
1865 | use AnyEvent; |
|
|
1866 | |
|
|
1867 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1868 | be used to probe what backend is used and gain other information (which is |
|
|
1869 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and |
|
|
1870 | $ENV{PERL_ANYEGENT_STRICT}. |
|
|
1871 | |
|
|
1872 | |
|
|
1873 | =head1 BUGS |
|
|
1874 | |
|
|
1875 | Perl 5.8 has numerous memleaks that sometimes hit this module and are hard |
|
|
1876 | to work around. If you suffer from memleaks, first upgrade to Perl 5.10 |
|
|
1877 | and check wether the leaks still show up. (Perl 5.10.0 has other annoying |
|
|
1878 | memleaks, such as leaking on C<map> and C<grep> but it is usually not as |
|
|
1879 | pronounced). |
|
|
1880 | |
864 | |
1881 | |
865 | =head1 SEE ALSO |
1882 | =head1 SEE ALSO |
866 | |
1883 | |
867 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1884 | Utility functions: L<AnyEvent::Util>. |
868 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
|
|
869 | L<Event::Lib>, L<Qt>. |
|
|
870 | |
1885 | |
871 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
1886 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
872 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
1887 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
873 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
1888 | |
|
|
1889 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
|
|
1890 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
1891 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
874 | L<AnyEvent::Impl::Qt>. |
1892 | L<AnyEvent::Impl::POE>. |
875 | |
1893 | |
|
|
1894 | Non-blocking file handles, sockets, TCP clients and |
|
|
1895 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1896 | |
|
|
1897 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1898 | |
|
|
1899 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1900 | |
876 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
1901 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
|
|
1902 | |
877 | |
1903 | |
878 | =head1 AUTHOR |
1904 | =head1 AUTHOR |
879 | |
1905 | |
880 | Marc Lehmann <schmorp@schmorp.de> |
1906 | Marc Lehmann <schmorp@schmorp.de> |
881 | http://home.schmorp.de/ |
1907 | http://home.schmorp.de/ |
882 | |
1908 | |
883 | =cut |
1909 | =cut |
884 | |
1910 | |
885 | 1 |
1911 | 1 |
886 | |
1912 | |