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 | Event, Coro, Glib, Tk, Perl - 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 wether 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, and AnyEvent |
49 | the statement "there can only be one" is a bitter reality: In general, |
35 | helps hiding the differences. |
50 | only one event loop can be active at the same time in a process. AnyEvent |
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51 | cannot change this, but it can hide the differences between those event |
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52 | loops. |
36 | |
53 | |
37 | 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 |
38 | 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 |
39 | religion, a way of living, and most importantly: without forcing your |
56 | religion, a way of living, and most importantly: without forcing your |
40 | 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 |
41 | model you use. |
58 | model you use. |
42 | |
59 | |
43 | For modules like POE or IO::Async (which is actually doing all I/O |
60 | For modules like POE or IO::Async (which is a total misnomer as it is |
44 | I<synchronously>...), using them in your module is like joining a |
61 | actually doing all I/O I<synchronously>...), using them in your module is |
45 | cult: After you joined, you are dependent on them and you cannot use |
62 | like joining a cult: After you joined, you are dependent on them and you |
46 | anything else, as it is simply incompatible to everything that isn't |
63 | cannot use anything else, as they are simply incompatible to everything |
47 | itself. |
64 | that isn't them. What's worse, all the potential users of your |
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65 | module are I<also> forced to use the same event loop you use. |
48 | |
66 | |
49 | AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk |
67 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
50 | works fine etc. etc. but none of these work together with the rest: POE |
68 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
51 | + IO::Async? no go. Tk + Event? no go. If your module uses one of |
69 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if |
52 | those, every user of your module has to use it, too. If your module |
70 | your module uses one of those, every user of your module has to use it, |
53 | uses AnyEvent, it works transparently with all event models it supports |
71 | too. But if your module uses AnyEvent, it works transparently with all |
54 | (including stuff like POE and IO::Async). |
72 | event models it supports (including stuff like IO::Async, as long as those |
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73 | use one of the supported event loops. It is trivial to add new event loops |
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74 | to AnyEvent, too, so it is future-proof). |
55 | |
75 | |
56 | In addition of 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 |
57 | 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 |
58 | modules, you get an enourmous amount of code and strict rules you have |
78 | modules, you get an enormous amount of code and strict rules you have to |
59 | to follow. AnyEvent, on the other hand, is lean and to the point by only |
79 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
60 | offering the functionality that is useful, in as thin as a wrapper as |
80 | offering the functionality that is necessary, in as thin as a wrapper as |
61 | technically possible. |
81 | technically possible. |
62 | |
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 | |
63 | 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 |
64 | 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 |
65 | model, you should I<not> use this module. |
91 | model, you should I<not> use this module. |
66 | |
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67 | |
92 | |
68 | =head1 DESCRIPTION |
93 | =head1 DESCRIPTION |
69 | |
94 | |
70 | L<AnyEvent> provides an identical interface to multiple event loops. This |
95 | L<AnyEvent> provides an identical interface to multiple event loops. This |
71 | allows module authors to utilise an event loop without forcing module |
96 | allows module authors to utilise an event loop without forcing module |
72 | users to use the same event loop (as only a single event loop can coexist |
97 | users to use the same event loop (as only a single event loop can coexist |
73 | peacefully at any one time). |
98 | peacefully at any one time). |
74 | |
99 | |
75 | The interface itself is vaguely similar but not identical to the Event |
100 | The interface itself is vaguely similar, but not identical to the L<Event> |
76 | module. |
101 | module. |
77 | |
102 | |
78 | On the first call of any method, the module tries to detect the currently |
103 | During the first call of any watcher-creation method, the module tries |
79 | loaded event loop by probing wether any of the following modules is |
104 | to detect the currently loaded event loop by probing whether one of the |
80 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
105 | following modules is already loaded: L<EV>, |
81 | used. If none is found, the module tries to load these modules in the |
106 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
82 | order given. The first one that could be successfully loaded will be |
107 | L<POE>. The first one found is used. If none are found, the module tries |
83 | used. If still none could be found, AnyEvent will fall back to a pure-perl |
108 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
84 | event loop, which is also not very efficient. |
109 | adaptor should always succeed) in the order given. The first one that can |
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110 | be successfully loaded will be used. If, after this, still none could be |
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111 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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112 | very efficient, but should work everywhere. |
85 | |
113 | |
86 | Because AnyEvent first checks for modules that are already loaded, loading |
114 | Because AnyEvent first checks for modules that are already loaded, loading |
87 | an Event model explicitly before first using AnyEvent will likely make |
115 | an event model explicitly before first using AnyEvent will likely make |
88 | that model the default. For example: |
116 | that model the default. For example: |
89 | |
117 | |
90 | use Tk; |
118 | use Tk; |
91 | use AnyEvent; |
119 | use AnyEvent; |
92 | |
120 | |
93 | # .. AnyEvent will likely default to Tk |
121 | # .. AnyEvent will likely default to Tk |
94 | |
122 | |
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123 | The I<likely> means that, if any module loads another event model and |
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124 | starts using it, all bets are off. Maybe you should tell their authors to |
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125 | use AnyEvent so their modules work together with others seamlessly... |
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126 | |
95 | The pure-perl implementation of AnyEvent is called |
127 | The pure-perl implementation of AnyEvent is called |
96 | 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 |
97 | explicitly. |
129 | explicitly and enjoy the high availability of that event loop :) |
98 | |
130 | |
99 | =head1 WATCHERS |
131 | =head1 WATCHERS |
100 | |
132 | |
101 | 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 |
102 | 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 |
103 | the callback to call, the filehandle to watch, etc. |
135 | the callback to call, the file handle to watch, etc. |
104 | |
136 | |
105 | These watchers are normal Perl objects with normal Perl lifetime. After |
137 | These watchers are normal Perl objects with normal Perl lifetime. After |
106 | creating a watcher it will immediately "watch" for events and invoke |
138 | creating a watcher it will immediately "watch" for events and invoke the |
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139 | callback when the event occurs (of course, only when the event model |
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140 | is in control). |
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141 | |
107 | the callback. To disable the watcher you have to destroy it (e.g. by |
142 | To disable the watcher you have to destroy it (e.g. by setting the |
108 | setting the variable that stores it to C<undef> or otherwise deleting all |
143 | variable you store it in to C<undef> or otherwise deleting all references |
109 | references to it). |
144 | to it). |
110 | |
145 | |
111 | All watchers are created by calling a method on the C<AnyEvent> class. |
146 | All watchers are created by calling a method on the C<AnyEvent> class. |
112 | |
147 | |
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148 | Many watchers either are used with "recursion" (repeating timers for |
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149 | example), or need to refer to their watcher object in other ways. |
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150 | |
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151 | An any way to achieve that is this pattern: |
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152 | |
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153 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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154 | # you can use $w here, for example to undef it |
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155 | undef $w; |
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156 | }); |
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157 | |
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158 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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159 | my variables are only visible after the statement in which they are |
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160 | declared. |
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161 | |
113 | =head2 IO WATCHERS |
162 | =head2 I/O WATCHERS |
114 | |
163 | |
115 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
164 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
116 | the following mandatory arguments: |
165 | with the following mandatory key-value pairs as arguments: |
117 | |
166 | |
118 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
167 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events |
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168 | (AnyEvent might or might not keep a reference to this file handle). C<poll> |
119 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
169 | must be a string that is either C<r> or C<w>, which creates a watcher |
120 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback |
170 | waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the |
121 | to invoke everytime the filehandle becomes ready. |
171 | callback to invoke each time the file handle becomes ready. |
122 | |
172 | |
123 | Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
173 | Although the callback might get passed parameters, their value and |
124 | a socket you can have one r + one w, not any more (limitation comes from |
174 | presence is undefined and you cannot rely on them. Portable AnyEvent |
125 | Tk - if you are sure you are not using Tk this limitation is gone). |
175 | callbacks cannot use arguments passed to I/O watcher callbacks. |
126 | |
176 | |
127 | Filehandles will be kept alive, so as long as the watcher exists, the |
177 | The I/O watcher might use the underlying file descriptor or a copy of it. |
128 | filehandle exists, too. |
178 | You must not close a file handle as long as any watcher is active on the |
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179 | underlying file descriptor. |
129 | |
180 | |
130 | Example: |
181 | Some event loops issue spurious readyness notifications, so you should |
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182 | always use non-blocking calls when reading/writing from/to your file |
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183 | handles. |
131 | |
184 | |
132 | # wait for readability of STDIN, then read a line and disable the watcher |
185 | Example: wait for readability of STDIN, then read a line and disable the |
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186 | watcher. |
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187 | |
133 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
188 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
134 | chomp (my $input = <STDIN>); |
189 | chomp (my $input = <STDIN>); |
135 | warn "read: $input\n"; |
190 | warn "read: $input\n"; |
136 | undef $w; |
191 | undef $w; |
137 | }); |
192 | }); |
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… | |
139 | =head2 TIME WATCHERS |
194 | =head2 TIME WATCHERS |
140 | |
195 | |
141 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
196 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
142 | method with the following mandatory arguments: |
197 | method with the following mandatory arguments: |
143 | |
198 | |
144 | C<after> after how many seconds (fractions are supported) should the timer |
199 | C<after> specifies after how many seconds (fractional values are |
145 | activate. C<cb> the callback to invoke. |
200 | supported) the callback should be invoked. C<cb> is the callback to invoke |
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201 | in that case. |
146 | |
202 | |
147 | The timer callback will be invoked at most once: if you want a repeating |
203 | Although the callback might get passed parameters, their value and |
148 | timer you have to create a new watcher (this is a limitation by both Tk |
204 | presence is undefined and you cannot rely on them. Portable AnyEvent |
149 | and Glib). |
205 | callbacks cannot use arguments passed to time watcher callbacks. |
150 | |
206 | |
151 | Example: |
207 | The callback will normally be invoked once only. If you specify another |
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208 | parameter, C<interval>, as a strictly positive number (> 0), then the |
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209 | callback will be invoked regularly at that interval (in fractional |
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210 | seconds) after the first invocation. If C<interval> is specified with a |
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211 | false value, then it is treated as if it were missing. |
152 | |
212 | |
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213 | The callback will be rescheduled before invoking the callback, but no |
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214 | attempt is done to avoid timer drift in most backends, so the interval is |
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215 | only approximate. |
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216 | |
153 | # fire an event after 7.7 seconds |
217 | Example: fire an event after 7.7 seconds. |
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218 | |
154 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
219 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
155 | warn "timeout\n"; |
220 | warn "timeout\n"; |
156 | }); |
221 | }); |
157 | |
222 | |
158 | # to cancel the timer: |
223 | # to cancel the timer: |
159 | undef $w; |
224 | undef $w; |
160 | |
225 | |
161 | =head2 CONDITION WATCHERS |
226 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
162 | |
227 | |
163 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
228 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
164 | method without any arguments. |
229 | warn "timeout\n"; |
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230 | }; |
165 | |
231 | |
166 | A condition watcher watches for a condition - precisely that the C<< |
232 | =head3 TIMING ISSUES |
167 | ->broadcast >> method has been called. |
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168 | |
233 | |
169 | Note that condition watchers recurse into the event loop - if you have |
234 | There are two ways to handle timers: based on real time (relative, "fire |
170 | two watchers that call C<< ->wait >> in a round-robbin fashion, you |
235 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
171 | lose. Therefore, condition watchers are good to export to your caller, but |
236 | o'clock"). |
172 | you should avoid making a blocking wait, at least in callbacks, as this |
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173 | usually asks for trouble. |
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174 | |
237 | |
175 | The watcher has only two methods: |
238 | While most event loops expect timers to specified in a relative way, they |
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239 | use absolute time internally. This makes a difference when your clock |
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240 | "jumps", for example, when ntp decides to set your clock backwards from |
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241 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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242 | fire "after" a second might actually take six years to finally fire. |
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243 | |
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244 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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245 | about these issues is L<EV>, which offers both relative (ev_timer, based |
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246 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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247 | timers. |
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248 | |
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249 | AnyEvent always prefers relative timers, if available, matching the |
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250 | AnyEvent API. |
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251 | |
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252 | AnyEvent has two additional methods that return the "current time": |
176 | |
253 | |
177 | =over 4 |
254 | =over 4 |
178 | |
255 | |
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256 | =item AnyEvent->time |
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257 | |
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258 | This returns the "current wallclock time" as a fractional number of |
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259 | seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time> |
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260 | return, and the result is guaranteed to be compatible with those). |
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261 | |
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262 | It progresses independently of any event loop processing, i.e. each call |
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263 | will check the system clock, which usually gets updated frequently. |
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264 | |
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265 | =item AnyEvent->now |
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266 | |
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267 | This also returns the "current wallclock time", but unlike C<time>, above, |
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268 | this value might change only once per event loop iteration, depending on |
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269 | the event loop (most return the same time as C<time>, above). This is the |
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270 | time that AnyEvent's timers get scheduled against. |
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271 | |
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272 | I<In almost all cases (in all cases if you don't care), this is the |
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273 | function to call when you want to know the current time.> |
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274 | |
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275 | This function is also often faster then C<< AnyEvent->time >>, and |
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276 | thus the preferred method if you want some timestamp (for example, |
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277 | L<AnyEvent::Handle> uses this to update it's activity timeouts). |
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278 | |
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279 | The rest of this section is only of relevance if you try to be very exact |
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280 | with your timing, you can skip it without bad conscience. |
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281 | |
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282 | For a practical example of when these times differ, consider L<Event::Lib> |
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283 | and L<EV> and the following set-up: |
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284 | |
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285 | The event loop is running and has just invoked one of your callback at |
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286 | time=500 (assume no other callbacks delay processing). In your callback, |
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287 | you wait a second by executing C<sleep 1> (blocking the process for a |
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288 | second) and then (at time=501) you create a relative timer that fires |
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289 | after three seconds. |
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290 | |
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291 | With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will |
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292 | both return C<501>, because that is the current time, and the timer will |
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293 | be scheduled to fire at time=504 (C<501> + C<3>). |
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294 | |
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295 | With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current |
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296 | time), but C<< AnyEvent->now >> returns C<500>, as that is the time the |
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297 | last event processing phase started. With L<EV>, your timer gets scheduled |
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298 | to run at time=503 (C<500> + C<3>). |
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299 | |
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300 | In one sense, L<Event::Lib> is more exact, as it uses the current time |
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301 | regardless of any delays introduced by event processing. However, most |
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302 | callbacks do not expect large delays in processing, so this causes a |
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303 | higher drift (and a lot more system calls to get the current time). |
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304 | |
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305 | In another sense, L<EV> is more exact, as your timer will be scheduled at |
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306 | the same time, regardless of how long event processing actually took. |
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307 | |
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308 | In either case, if you care (and in most cases, you don't), then you |
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309 | can get whatever behaviour you want with any event loop, by taking the |
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310 | difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into |
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311 | account. |
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312 | |
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313 | =back |
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314 | |
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315 | =head2 SIGNAL WATCHERS |
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316 | |
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317 | You can watch for signals using a signal watcher, C<signal> is the signal |
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318 | I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl |
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319 | callback to be invoked whenever a signal occurs. |
|
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320 | |
|
|
321 | Although the callback might get passed parameters, their value and |
|
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322 | presence is undefined and you cannot rely on them. Portable AnyEvent |
|
|
323 | callbacks cannot use arguments passed to signal watcher callbacks. |
|
|
324 | |
|
|
325 | Multiple signal occurrences can be clumped together into one callback |
|
|
326 | invocation, and callback invocation will be synchronous. Synchronous means |
|
|
327 | that it might take a while until the signal gets handled by the process, |
|
|
328 | but it is guaranteed not to interrupt any other callbacks. |
|
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329 | |
|
|
330 | The main advantage of using these watchers is that you can share a signal |
|
|
331 | between multiple watchers. |
|
|
332 | |
|
|
333 | This watcher might use C<%SIG>, so programs overwriting those signals |
|
|
334 | directly will likely not work correctly. |
|
|
335 | |
|
|
336 | Example: exit on SIGINT |
|
|
337 | |
|
|
338 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
339 | |
|
|
340 | =head2 CHILD PROCESS WATCHERS |
|
|
341 | |
|
|
342 | You can also watch on a child process exit and catch its exit status. |
|
|
343 | |
|
|
344 | The child process is specified by the C<pid> argument (if set to C<0>, it |
|
|
345 | watches for any child process exit). The watcher will trigger as often |
|
|
346 | as status change for the child are received. This works by installing a |
|
|
347 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
|
|
348 | and exit status (as returned by waitpid), so unlike other watcher types, |
|
|
349 | you I<can> rely on child watcher callback arguments. |
|
|
350 | |
|
|
351 | There is a slight catch to child watchers, however: you usually start them |
|
|
352 | I<after> the child process was created, and this means the process could |
|
|
353 | have exited already (and no SIGCHLD will be sent anymore). |
|
|
354 | |
|
|
355 | Not all event models handle this correctly (POE doesn't), but even for |
|
|
356 | event models that I<do> handle this correctly, they usually need to be |
|
|
357 | loaded before the process exits (i.e. before you fork in the first place). |
|
|
358 | |
|
|
359 | This means you cannot create a child watcher as the very first thing in an |
|
|
360 | AnyEvent program, you I<have> to create at least one watcher before you |
|
|
361 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
|
|
362 | |
|
|
363 | Example: fork a process and wait for it |
|
|
364 | |
|
|
365 | my $done = AnyEvent->condvar; |
|
|
366 | |
|
|
367 | my $pid = fork or exit 5; |
|
|
368 | |
|
|
369 | my $w = AnyEvent->child ( |
|
|
370 | pid => $pid, |
|
|
371 | cb => sub { |
|
|
372 | my ($pid, $status) = @_; |
|
|
373 | warn "pid $pid exited with status $status"; |
|
|
374 | $done->send; |
|
|
375 | }, |
|
|
376 | ); |
|
|
377 | |
|
|
378 | # do something else, then wait for process exit |
|
|
379 | $done->recv; |
|
|
380 | |
|
|
381 | =head2 CONDITION VARIABLES |
|
|
382 | |
|
|
383 | If you are familiar with some event loops you will know that all of them |
|
|
384 | require you to run some blocking "loop", "run" or similar function that |
|
|
385 | will actively watch for new events and call your callbacks. |
|
|
386 | |
|
|
387 | AnyEvent is different, it expects somebody else to run the event loop and |
|
|
388 | will only block when necessary (usually when told by the user). |
|
|
389 | |
|
|
390 | The instrument to do that is called a "condition variable", so called |
|
|
391 | because they represent a condition that must become true. |
|
|
392 | |
|
|
393 | Condition variables can be created by calling the C<< AnyEvent->condvar |
|
|
394 | |
|
|
395 | >> method, usually without arguments. The only argument pair allowed is |
|
|
396 | |
|
|
397 | C<cb>, which specifies a callback to be called when the condition variable |
|
|
398 | becomes true, with the condition variable as the first argument (but not |
|
|
399 | the results). |
|
|
400 | |
|
|
401 | After creation, the condition variable is "false" until it becomes "true" |
|
|
402 | by calling the C<send> method (or calling the condition variable as if it |
|
|
403 | were a callback, read about the caveats in the description for the C<< |
|
|
404 | ->send >> method). |
|
|
405 | |
|
|
406 | Condition variables are similar to callbacks, except that you can |
|
|
407 | optionally wait for them. They can also be called merge points - points |
|
|
408 | in time where multiple outstanding events have been processed. And yet |
|
|
409 | another way to call them is transactions - each condition variable can be |
|
|
410 | used to represent a transaction, which finishes at some point and delivers |
|
|
411 | a result. |
|
|
412 | |
|
|
413 | Condition variables are very useful to signal that something has finished, |
|
|
414 | for example, if you write a module that does asynchronous http requests, |
|
|
415 | then a condition variable would be the ideal candidate to signal the |
|
|
416 | availability of results. The user can either act when the callback is |
|
|
417 | called or can synchronously C<< ->recv >> for the results. |
|
|
418 | |
|
|
419 | You can also use them to simulate traditional event loops - for example, |
|
|
420 | you can block your main program until an event occurs - for example, you |
|
|
421 | could C<< ->recv >> in your main program until the user clicks the Quit |
|
|
422 | button of your app, which would C<< ->send >> the "quit" event. |
|
|
423 | |
|
|
424 | Note that condition variables recurse into the event loop - if you have |
|
|
425 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
|
|
426 | lose. Therefore, condition variables are good to export to your caller, but |
|
|
427 | you should avoid making a blocking wait yourself, at least in callbacks, |
|
|
428 | as this asks for trouble. |
|
|
429 | |
|
|
430 | Condition variables are represented by hash refs in perl, and the keys |
|
|
431 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
|
|
432 | easy (it is often useful to build your own transaction class on top of |
|
|
433 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
|
|
434 | it's C<new> method in your own C<new> method. |
|
|
435 | |
|
|
436 | There are two "sides" to a condition variable - the "producer side" which |
|
|
437 | eventually calls C<< -> send >>, and the "consumer side", which waits |
|
|
438 | for the send to occur. |
|
|
439 | |
|
|
440 | Example: wait for a timer. |
|
|
441 | |
|
|
442 | # wait till the result is ready |
|
|
443 | my $result_ready = AnyEvent->condvar; |
|
|
444 | |
|
|
445 | # do something such as adding a timer |
|
|
446 | # or socket watcher the calls $result_ready->send |
|
|
447 | # when the "result" is ready. |
|
|
448 | # in this case, we simply use a timer: |
|
|
449 | my $w = AnyEvent->timer ( |
|
|
450 | after => 1, |
|
|
451 | cb => sub { $result_ready->send }, |
|
|
452 | ); |
|
|
453 | |
|
|
454 | # this "blocks" (while handling events) till the callback |
|
|
455 | # calls send |
|
|
456 | $result_ready->recv; |
|
|
457 | |
|
|
458 | Example: wait for a timer, but take advantage of the fact that |
|
|
459 | condition variables are also code references. |
|
|
460 | |
|
|
461 | my $done = AnyEvent->condvar; |
|
|
462 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
|
|
463 | $done->recv; |
|
|
464 | |
|
|
465 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
466 | callbacks. This is how you make a synchronous call, for example from |
|
|
467 | the main program: |
|
|
468 | |
|
|
469 | use AnyEvent::CouchDB; |
|
|
470 | |
|
|
471 | ... |
|
|
472 | |
|
|
473 | my @info = $couchdb->info->recv; |
|
|
474 | |
|
|
475 | And this is how you would just ste a callback to be called whenever the |
|
|
476 | results are available: |
|
|
477 | |
|
|
478 | $couchdb->info->cb (sub { |
|
|
479 | my @info = $_[0]->recv; |
|
|
480 | }); |
|
|
481 | |
|
|
482 | =head3 METHODS FOR PRODUCERS |
|
|
483 | |
|
|
484 | These methods should only be used by the producing side, i.e. the |
|
|
485 | code/module that eventually sends the signal. Note that it is also |
|
|
486 | the producer side which creates the condvar in most cases, but it isn't |
|
|
487 | uncommon for the consumer to create it as well. |
|
|
488 | |
|
|
489 | =over 4 |
|
|
490 | |
|
|
491 | =item $cv->send (...) |
|
|
492 | |
|
|
493 | Flag the condition as ready - a running C<< ->recv >> and all further |
|
|
494 | calls to C<recv> will (eventually) return after this method has been |
|
|
495 | called. If nobody is waiting the send will be remembered. |
|
|
496 | |
|
|
497 | If a callback has been set on the condition variable, it is called |
|
|
498 | immediately from within send. |
|
|
499 | |
|
|
500 | Any arguments passed to the C<send> call will be returned by all |
|
|
501 | future C<< ->recv >> calls. |
|
|
502 | |
|
|
503 | Condition variables are overloaded so one can call them directly |
|
|
504 | (as a code reference). Calling them directly is the same as calling |
|
|
505 | C<send>. Note, however, that many C-based event loops do not handle |
|
|
506 | overloading, so as tempting as it may be, passing a condition variable |
|
|
507 | instead of a callback does not work. Both the pure perl and EV loops |
|
|
508 | support overloading, however, as well as all functions that use perl to |
|
|
509 | invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for |
|
|
510 | example). |
|
|
511 | |
|
|
512 | =item $cv->croak ($error) |
|
|
513 | |
|
|
514 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
|
|
515 | C<Carp::croak> with the given error message/object/scalar. |
|
|
516 | |
|
|
517 | This can be used to signal any errors to the condition variable |
|
|
518 | user/consumer. |
|
|
519 | |
|
|
520 | =item $cv->begin ([group callback]) |
|
|
521 | |
179 | =item $cv->wait |
522 | =item $cv->end |
180 | |
523 | |
181 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
524 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
525 | |
|
|
526 | These two methods can be used to combine many transactions/events into |
|
|
527 | one. For example, a function that pings many hosts in parallel might want |
|
|
528 | to use a condition variable for the whole process. |
|
|
529 | |
|
|
530 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
531 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
532 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
533 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
534 | callback was set, C<send> will be called without any arguments. |
|
|
535 | |
|
|
536 | Let's clarify this with the ping example: |
|
|
537 | |
|
|
538 | my $cv = AnyEvent->condvar; |
|
|
539 | |
|
|
540 | my %result; |
|
|
541 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
542 | |
|
|
543 | for my $host (@list_of_hosts) { |
|
|
544 | $cv->begin; |
|
|
545 | ping_host_then_call_callback $host, sub { |
|
|
546 | $result{$host} = ...; |
|
|
547 | $cv->end; |
|
|
548 | }; |
|
|
549 | } |
|
|
550 | |
|
|
551 | $cv->end; |
|
|
552 | |
|
|
553 | This code fragment supposedly pings a number of hosts and calls |
|
|
554 | C<send> after results for all then have have been gathered - in any |
|
|
555 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
556 | each ping request and calls C<end> when it has received some result for |
|
|
557 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
558 | results arrive is not relevant. |
|
|
559 | |
|
|
560 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
561 | loop, which serves two important purposes: first, it sets the callback |
|
|
562 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
563 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
564 | doesn't execute once). |
|
|
565 | |
|
|
566 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
567 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
568 | is called at least once, and then, for each subrequest you start, call |
|
|
569 | C<begin> and for each subrequest you finish, call C<end>. |
|
|
570 | |
|
|
571 | =back |
|
|
572 | |
|
|
573 | =head3 METHODS FOR CONSUMERS |
|
|
574 | |
|
|
575 | These methods should only be used by the consuming side, i.e. the |
|
|
576 | code awaits the condition. |
|
|
577 | |
|
|
578 | =over 4 |
|
|
579 | |
|
|
580 | =item $cv->recv |
|
|
581 | |
|
|
582 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
182 | called on c<$cv>, while servicing other watchers normally. |
583 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
584 | normally. |
183 | |
585 | |
184 | You can only wait once on a condition - additional calls will return |
586 | You can only wait once on a condition - additional calls are valid but |
185 | immediately. |
587 | will return immediately. |
|
|
588 | |
|
|
589 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
590 | function will call C<croak>. |
|
|
591 | |
|
|
592 | In list context, all parameters passed to C<send> will be returned, |
|
|
593 | in scalar context only the first one will be returned. |
186 | |
594 | |
187 | Not all event models support a blocking wait - some die in that case |
595 | Not all event models support a blocking wait - some die in that case |
188 | (programs might want to do that so they stay interactive), so I<if you |
596 | (programs might want to do that to stay interactive), so I<if you are |
189 | are using this from a module, never require a blocking wait>, but let the |
597 | using this from a module, never require a blocking wait>, but let the |
190 | caller decide wether the call will block or not (for example, by coupling |
598 | caller decide whether the call will block or not (for example, by coupling |
191 | condition variables with some kind of request results and supporting |
599 | condition variables with some kind of request results and supporting |
192 | callbacks so the caller knows that getting the result will not block, |
600 | callbacks so the caller knows that getting the result will not block, |
193 | while still suppporting blocking waits if the caller so desires). |
601 | while still supporting blocking waits if the caller so desires). |
194 | |
602 | |
195 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
603 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
196 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
604 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
197 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
605 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
198 | can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event> |
606 | can supply. |
199 | explicitly support concurrent C<< ->wait >>'s from different coroutines, |
|
|
200 | however). |
|
|
201 | |
607 | |
202 | =item $cv->broadcast |
608 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
609 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
610 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
611 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
612 | coroutine (one that doesn't run the event loop). |
203 | |
613 | |
204 | Flag the condition as ready - a running C<< ->wait >> and all further |
614 | You can ensure that C<< -recv >> never blocks by setting a callback and |
205 | calls to C<wait> will return after this method has been called. If nobody |
615 | only calling C<< ->recv >> from within that callback (or at a later |
206 | is waiting the broadcast will be remembered.. |
616 | time). This will work even when the event loop does not support blocking |
|
|
617 | waits otherwise. |
207 | |
618 | |
208 | Example: |
619 | =item $bool = $cv->ready |
209 | |
620 | |
210 | # wait till the result is ready |
621 | Returns true when the condition is "true", i.e. whether C<send> or |
211 | my $result_ready = AnyEvent->condvar; |
622 | C<croak> have been called. |
212 | |
623 | |
213 | # do something such as adding a timer |
624 | =item $cb = $cv->cb ($cb->($cv)) |
214 | # or socket watcher the calls $result_ready->broadcast |
|
|
215 | # when the "result" is ready. |
|
|
216 | |
625 | |
217 | $result_ready->wait; |
626 | This is a mutator function that returns the callback set and optionally |
|
|
627 | replaces it before doing so. |
|
|
628 | |
|
|
629 | The callback will be called when the condition becomes "true", i.e. when |
|
|
630 | C<send> or C<croak> are called, with the only argument being the condition |
|
|
631 | variable itself. Calling C<recv> inside the callback or at any later time |
|
|
632 | is guaranteed not to block. |
218 | |
633 | |
219 | =back |
634 | =back |
220 | |
635 | |
221 | =head2 SIGNAL WATCHERS |
636 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
222 | |
|
|
223 | You can listen for signals using a signal watcher, C<signal> is the signal |
|
|
224 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
|
|
225 | together into one callback invocation, and callback invocation might or |
|
|
226 | might not be asynchronous. |
|
|
227 | |
|
|
228 | These watchers might use C<%SIG>, so programs overwriting those signals |
|
|
229 | directly will likely not work correctly. |
|
|
230 | |
|
|
231 | Example: exit on SIGINT |
|
|
232 | |
|
|
233 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
234 | |
|
|
235 | =head2 CHILD PROCESS WATCHERS |
|
|
236 | |
|
|
237 | You can also listen for the status of a child process specified by the |
|
|
238 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
|
|
239 | trigger as often as status change for the child are received. This works |
|
|
240 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
|
|
241 | the pid and exit status (as returned by waitpid). |
|
|
242 | |
|
|
243 | Example: wait for pid 1333 |
|
|
244 | |
|
|
245 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
|
|
246 | |
|
|
247 | =head1 GLOBALS |
|
|
248 | |
637 | |
249 | =over 4 |
638 | =over 4 |
250 | |
639 | |
251 | =item $AnyEvent::MODEL |
640 | =item $AnyEvent::MODEL |
252 | |
641 | |
… | |
… | |
256 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
645 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
257 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
646 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
258 | |
647 | |
259 | The known classes so far are: |
648 | The known classes so far are: |
260 | |
649 | |
261 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
|
|
262 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
650 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
263 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
|
|
264 | AnyEvent::Impl::Event based on Event, also second best choice :) |
651 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
652 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
265 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
653 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
266 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
654 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
267 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
655 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
656 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
657 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
658 | |
|
|
659 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
660 | watching file handles. However, you can use WxWidgets through the |
|
|
661 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
662 | second, which was considered to be too horrible to even consider for |
|
|
663 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
664 | it's adaptor. |
|
|
665 | |
|
|
666 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
667 | autodetecting them. |
268 | |
668 | |
269 | =item AnyEvent::detect |
669 | =item AnyEvent::detect |
270 | |
670 | |
271 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
671 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
272 | necessary. You should only call this function right before you would have |
672 | if necessary. You should only call this function right before you would |
273 | created an AnyEvent watcher anyway, that is, very late at runtime. |
673 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
674 | runtime. |
|
|
675 | |
|
|
676 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
677 | |
|
|
678 | Arranges for the code block to be executed as soon as the event model is |
|
|
679 | autodetected (or immediately if this has already happened). |
|
|
680 | |
|
|
681 | If called in scalar or list context, then it creates and returns an object |
|
|
682 | that automatically removes the callback again when it is destroyed. See |
|
|
683 | L<Coro::BDB> for a case where this is useful. |
|
|
684 | |
|
|
685 | =item @AnyEvent::post_detect |
|
|
686 | |
|
|
687 | If there are any code references in this array (you can C<push> to it |
|
|
688 | before or after loading AnyEvent), then they will called directly after |
|
|
689 | the event loop has been chosen. |
|
|
690 | |
|
|
691 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
692 | if it contains a true value then the event loop has already been detected, |
|
|
693 | and the array will be ignored. |
|
|
694 | |
|
|
695 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
274 | |
696 | |
275 | =back |
697 | =back |
276 | |
698 | |
277 | =head1 WHAT TO DO IN A MODULE |
699 | =head1 WHAT TO DO IN A MODULE |
278 | |
700 | |
279 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
701 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
280 | freely, but you should not load a specific event module or rely on it. |
702 | freely, but you should not load a specific event module or rely on it. |
281 | |
703 | |
282 | Be careful when you create watchers in the module body - Anyevent will |
704 | Be careful when you create watchers in the module body - AnyEvent will |
283 | decide which event module to use as soon as the first method is called, so |
705 | decide which event module to use as soon as the first method is called, so |
284 | by calling AnyEvent in your module body you force the user of your module |
706 | by calling AnyEvent in your module body you force the user of your module |
285 | to load the event module first. |
707 | to load the event module first. |
286 | |
708 | |
|
|
709 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
|
|
710 | the C<< ->send >> method has been called on it already. This is |
|
|
711 | because it will stall the whole program, and the whole point of using |
|
|
712 | events is to stay interactive. |
|
|
713 | |
|
|
714 | It is fine, however, to call C<< ->recv >> when the user of your module |
|
|
715 | requests it (i.e. if you create a http request object ad have a method |
|
|
716 | called C<results> that returns the results, it should call C<< ->recv >> |
|
|
717 | freely, as the user of your module knows what she is doing. always). |
|
|
718 | |
287 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
719 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
288 | |
720 | |
289 | There will always be a single main program - the only place that should |
721 | There will always be a single main program - the only place that should |
290 | dictate which event model to use. |
722 | dictate which event model to use. |
291 | |
723 | |
292 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
724 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
293 | do anything special and let AnyEvent decide which implementation to chose. |
725 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
726 | decide which implementation to chose if some module relies on it. |
294 | |
727 | |
295 | If the main program relies on a specific event model (for example, in Gtk2 |
728 | If the main program relies on a specific event model - for example, in |
296 | programs you have to rely on either Glib or Glib::Event), you should load |
729 | Gtk2 programs you have to rely on the Glib module - you should load the |
297 | it before loading AnyEvent or any module that uses it, generally, as early |
730 | event module before loading AnyEvent or any module that uses it: generally |
298 | as possible. The reason is that modules might create watchers when they |
731 | speaking, you should load it as early as possible. The reason is that |
299 | are loaded, and AnyEvent will decide on the event model to use as soon as |
732 | modules might create watchers when they are loaded, and AnyEvent will |
300 | it creates watchers, and it might chose the wrong one unless you load the |
733 | decide on the event model to use as soon as it creates watchers, and it |
301 | correct one yourself. |
734 | might chose the wrong one unless you load the correct one yourself. |
302 | |
735 | |
303 | You can chose to use a rather inefficient pure-perl implementation by |
736 | You can chose to use a pure-perl implementation by loading the |
304 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
737 | C<AnyEvent::Impl::Perl> module, which gives you similar behaviour |
305 | generally better. |
738 | everywhere, but letting AnyEvent chose the model is generally better. |
|
|
739 | |
|
|
740 | =head2 MAINLOOP EMULATION |
|
|
741 | |
|
|
742 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
743 | only want to use AnyEvent), you do not want to run a specific event loop. |
|
|
744 | |
|
|
745 | In that case, you can use a condition variable like this: |
|
|
746 | |
|
|
747 | AnyEvent->condvar->recv; |
|
|
748 | |
|
|
749 | This has the effect of entering the event loop and looping forever. |
|
|
750 | |
|
|
751 | Note that usually your program has some exit condition, in which case |
|
|
752 | it is better to use the "traditional" approach of storing a condition |
|
|
753 | variable somewhere, waiting for it, and sending it when the program should |
|
|
754 | exit cleanly. |
|
|
755 | |
|
|
756 | |
|
|
757 | =head1 OTHER MODULES |
|
|
758 | |
|
|
759 | The following is a non-exhaustive list of additional modules that use |
|
|
760 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
761 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
762 | available via CPAN. |
|
|
763 | |
|
|
764 | =over 4 |
|
|
765 | |
|
|
766 | =item L<AnyEvent::Util> |
|
|
767 | |
|
|
768 | Contains various utility functions that replace often-used but blocking |
|
|
769 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
770 | |
|
|
771 | =item L<AnyEvent::Socket> |
|
|
772 | |
|
|
773 | Provides various utility functions for (internet protocol) sockets, |
|
|
774 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
775 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
776 | |
|
|
777 | =item L<AnyEvent::Handle> |
|
|
778 | |
|
|
779 | Provide read and write buffers, manages watchers for reads and writes, |
|
|
780 | supports raw and formatted I/O, I/O queued and fully transparent and |
|
|
781 | non-blocking SSL/TLS. |
|
|
782 | |
|
|
783 | =item L<AnyEvent::DNS> |
|
|
784 | |
|
|
785 | Provides rich asynchronous DNS resolver capabilities. |
|
|
786 | |
|
|
787 | =item L<AnyEvent::HTTP> |
|
|
788 | |
|
|
789 | A simple-to-use HTTP library that is capable of making a lot of concurrent |
|
|
790 | HTTP requests. |
|
|
791 | |
|
|
792 | =item L<AnyEvent::HTTPD> |
|
|
793 | |
|
|
794 | Provides a simple web application server framework. |
|
|
795 | |
|
|
796 | =item L<AnyEvent::FastPing> |
|
|
797 | |
|
|
798 | The fastest ping in the west. |
|
|
799 | |
|
|
800 | =item L<AnyEvent::DBI> |
|
|
801 | |
|
|
802 | Executes L<DBI> requests asynchronously in a proxy process. |
|
|
803 | |
|
|
804 | =item L<AnyEvent::AIO> |
|
|
805 | |
|
|
806 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
807 | programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent |
|
|
808 | together. |
|
|
809 | |
|
|
810 | =item L<AnyEvent::BDB> |
|
|
811 | |
|
|
812 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses |
|
|
813 | L<BDB> and AnyEvent together. |
|
|
814 | |
|
|
815 | =item L<AnyEvent::GPSD> |
|
|
816 | |
|
|
817 | A non-blocking interface to gpsd, a daemon delivering GPS information. |
|
|
818 | |
|
|
819 | =item L<AnyEvent::IGS> |
|
|
820 | |
|
|
821 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
822 | L<App::IGS>). |
|
|
823 | |
|
|
824 | =item L<Net::IRC3> |
|
|
825 | |
|
|
826 | AnyEvent based IRC client module family. |
|
|
827 | |
|
|
828 | =item L<Net::XMPP2> |
|
|
829 | |
|
|
830 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
831 | |
|
|
832 | =item L<Net::FCP> |
|
|
833 | |
|
|
834 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
835 | of AnyEvent. |
|
|
836 | |
|
|
837 | =item L<Event::ExecFlow> |
|
|
838 | |
|
|
839 | High level API for event-based execution flow control. |
|
|
840 | |
|
|
841 | =item L<Coro> |
|
|
842 | |
|
|
843 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
844 | |
|
|
845 | =item L<IO::Lambda> |
|
|
846 | |
|
|
847 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
848 | |
|
|
849 | =back |
306 | |
850 | |
307 | =cut |
851 | =cut |
308 | |
852 | |
309 | package AnyEvent; |
853 | package AnyEvent; |
310 | |
854 | |
311 | no warnings; |
855 | no warnings; |
312 | use strict; |
856 | use strict; |
313 | |
857 | |
314 | use Carp; |
858 | use Carp; |
315 | |
859 | |
316 | our $VERSION = '3.0'; |
860 | our $VERSION = 4.22; |
317 | our $MODEL; |
861 | our $MODEL; |
318 | |
862 | |
319 | our $AUTOLOAD; |
863 | our $AUTOLOAD; |
320 | our @ISA; |
864 | our @ISA; |
321 | |
865 | |
|
|
866 | our @REGISTRY; |
|
|
867 | |
|
|
868 | our $WIN32; |
|
|
869 | |
|
|
870 | BEGIN { |
|
|
871 | my $win32 = ! ! ($^O =~ /mswin32/i); |
|
|
872 | eval "sub WIN32(){ $win32 }"; |
|
|
873 | } |
|
|
874 | |
322 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
875 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
323 | |
876 | |
324 | our @REGISTRY; |
877 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
|
|
878 | |
|
|
879 | { |
|
|
880 | my $idx; |
|
|
881 | $PROTOCOL{$_} = ++$idx |
|
|
882 | for reverse split /\s*,\s*/, |
|
|
883 | $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
884 | } |
325 | |
885 | |
326 | my @models = ( |
886 | my @models = ( |
327 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
328 | [EV:: => AnyEvent::Impl::EV::], |
887 | [EV:: => AnyEvent::Impl::EV::], |
329 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
330 | [Event:: => AnyEvent::Impl::Event::], |
888 | [Event:: => AnyEvent::Impl::Event::], |
331 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
332 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
333 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
889 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
890 | # everything below here will not be autoprobed |
|
|
891 | # as the pureperl backend should work everywhere |
|
|
892 | # and is usually faster |
|
|
893 | [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles |
|
|
894 | [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers |
|
|
895 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
896 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
897 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
|
|
898 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
899 | [Prima:: => AnyEvent::Impl::POE::], |
334 | ); |
900 | ); |
335 | |
901 | |
336 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
902 | our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); |
|
|
903 | |
|
|
904 | our @post_detect; |
|
|
905 | |
|
|
906 | sub post_detect(&) { |
|
|
907 | my ($cb) = @_; |
|
|
908 | |
|
|
909 | if ($MODEL) { |
|
|
910 | $cb->(); |
|
|
911 | |
|
|
912 | 1 |
|
|
913 | } else { |
|
|
914 | push @post_detect, $cb; |
|
|
915 | |
|
|
916 | defined wantarray |
|
|
917 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
918 | : () |
|
|
919 | } |
|
|
920 | } |
|
|
921 | |
|
|
922 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
923 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
924 | } |
337 | |
925 | |
338 | sub detect() { |
926 | sub detect() { |
339 | unless ($MODEL) { |
927 | unless ($MODEL) { |
340 | no strict 'refs'; |
928 | no strict 'refs'; |
|
|
929 | local $SIG{__DIE__}; |
|
|
930 | |
|
|
931 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
932 | my $model = "AnyEvent::Impl::$1"; |
|
|
933 | if (eval "require $model") { |
|
|
934 | $MODEL = $model; |
|
|
935 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
936 | } else { |
|
|
937 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
938 | } |
|
|
939 | } |
341 | |
940 | |
342 | # check for already loaded models |
941 | # check for already loaded models |
|
|
942 | unless ($MODEL) { |
343 | for (@REGISTRY, @models) { |
943 | for (@REGISTRY, @models) { |
344 | my ($package, $model) = @$_; |
944 | my ($package, $model) = @$_; |
345 | if (${"$package\::VERSION"} > 0) { |
945 | if (${"$package\::VERSION"} > 0) { |
346 | if (eval "require $model") { |
946 | if (eval "require $model") { |
347 | $MODEL = $model; |
947 | $MODEL = $model; |
348 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
948 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
349 | last; |
949 | last; |
|
|
950 | } |
350 | } |
951 | } |
351 | } |
952 | } |
|
|
953 | |
|
|
954 | unless ($MODEL) { |
|
|
955 | # try to load a model |
|
|
956 | |
|
|
957 | for (@REGISTRY, @models) { |
|
|
958 | my ($package, $model) = @$_; |
|
|
959 | if (eval "require $package" |
|
|
960 | and ${"$package\::VERSION"} > 0 |
|
|
961 | and eval "require $model") { |
|
|
962 | $MODEL = $model; |
|
|
963 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
|
|
964 | last; |
|
|
965 | } |
|
|
966 | } |
|
|
967 | |
|
|
968 | $MODEL |
|
|
969 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
|
|
970 | } |
352 | } |
971 | } |
353 | |
972 | |
354 | unless ($MODEL) { |
973 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
355 | # try to load a model |
|
|
356 | |
|
|
357 | for (@REGISTRY, @models) { |
|
|
358 | my ($package, $model) = @$_; |
|
|
359 | if (eval "require $package" |
|
|
360 | and ${"$package\::VERSION"} > 0 |
|
|
361 | and eval "require $model") { |
|
|
362 | $MODEL = $model; |
|
|
363 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
|
|
364 | last; |
|
|
365 | } |
|
|
366 | } |
|
|
367 | |
|
|
368 | $MODEL |
|
|
369 | 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), Glib or Tk."; |
|
|
370 | } |
|
|
371 | |
974 | |
372 | unshift @ISA, $MODEL; |
975 | unshift @ISA, $MODEL; |
373 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
976 | |
|
|
977 | require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT}; |
|
|
978 | |
|
|
979 | (shift @post_detect)->() while @post_detect; |
374 | } |
980 | } |
375 | |
981 | |
376 | $MODEL |
982 | $MODEL |
377 | } |
983 | } |
378 | |
984 | |
… | |
… | |
386 | |
992 | |
387 | my $class = shift; |
993 | my $class = shift; |
388 | $class->$func (@_); |
994 | $class->$func (@_); |
389 | } |
995 | } |
390 | |
996 | |
|
|
997 | # utility function to dup a filehandle. this is used by many backends |
|
|
998 | # to support binding more than one watcher per filehandle (they usually |
|
|
999 | # allow only one watcher per fd, so we dup it to get a different one). |
|
|
1000 | sub _dupfh($$$$) { |
|
|
1001 | my ($poll, $fh, $r, $w) = @_; |
|
|
1002 | |
|
|
1003 | require Fcntl; |
|
|
1004 | |
|
|
1005 | # cygwin requires the fh mode to be matching, unix doesn't |
|
|
1006 | my ($rw, $mode) = $poll eq "r" ? ($r, "<") |
|
|
1007 | : $poll eq "w" ? ($w, ">") |
|
|
1008 | : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'"; |
|
|
1009 | |
|
|
1010 | open my $fh2, "$mode&" . fileno $fh |
|
|
1011 | or die "cannot dup() filehandle: $!"; |
|
|
1012 | |
|
|
1013 | # we assume CLOEXEC is already set by perl in all important cases |
|
|
1014 | |
|
|
1015 | ($fh2, $rw) |
|
|
1016 | } |
|
|
1017 | |
391 | package AnyEvent::Base; |
1018 | package AnyEvent::Base; |
392 | |
1019 | |
|
|
1020 | # default implementation for now and time |
|
|
1021 | |
|
|
1022 | use Time::HiRes (); |
|
|
1023 | |
|
|
1024 | sub time { Time::HiRes::time } |
|
|
1025 | sub now { Time::HiRes::time } |
|
|
1026 | |
393 | # default implementation for ->condvar, ->wait, ->broadcast |
1027 | # default implementation for ->condvar |
394 | |
1028 | |
395 | sub condvar { |
1029 | sub condvar { |
396 | bless \my $flag, "AnyEvent::Base::CondVar" |
1030 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
397 | } |
|
|
398 | |
|
|
399 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
400 | ${$_[0]}++; |
|
|
401 | } |
|
|
402 | |
|
|
403 | sub AnyEvent::Base::CondVar::wait { |
|
|
404 | AnyEvent->one_event while !${$_[0]}; |
|
|
405 | } |
1031 | } |
406 | |
1032 | |
407 | # default implementation for ->signal |
1033 | # default implementation for ->signal |
408 | |
1034 | |
409 | our %SIG_CB; |
1035 | our %SIG_CB; |
… | |
… | |
425 | sub AnyEvent::Base::Signal::DESTROY { |
1051 | sub AnyEvent::Base::Signal::DESTROY { |
426 | my ($signal, $cb) = @{$_[0]}; |
1052 | my ($signal, $cb) = @{$_[0]}; |
427 | |
1053 | |
428 | delete $SIG_CB{$signal}{$cb}; |
1054 | delete $SIG_CB{$signal}{$cb}; |
429 | |
1055 | |
430 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
1056 | delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; |
431 | } |
1057 | } |
432 | |
1058 | |
433 | # default implementation for ->child |
1059 | # default implementation for ->child |
434 | |
1060 | |
435 | our %PID_CB; |
1061 | our %PID_CB; |
… | |
… | |
462 | or Carp::croak "required option 'pid' is missing"; |
1088 | or Carp::croak "required option 'pid' is missing"; |
463 | |
1089 | |
464 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
1090 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
465 | |
1091 | |
466 | unless ($WNOHANG) { |
1092 | unless ($WNOHANG) { |
467 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
1093 | $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; |
468 | } |
1094 | } |
469 | |
1095 | |
470 | unless ($CHLD_W) { |
1096 | unless ($CHLD_W) { |
471 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
1097 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
472 | # child could be a zombie already, so make at least one round |
1098 | # child could be a zombie already, so make at least one round |
… | |
… | |
483 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
1109 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
484 | |
1110 | |
485 | undef $CHLD_W unless keys %PID_CB; |
1111 | undef $CHLD_W unless keys %PID_CB; |
486 | } |
1112 | } |
487 | |
1113 | |
|
|
1114 | package AnyEvent::CondVar; |
|
|
1115 | |
|
|
1116 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
1117 | |
|
|
1118 | package AnyEvent::CondVar::Base; |
|
|
1119 | |
|
|
1120 | use overload |
|
|
1121 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
1122 | fallback => 1; |
|
|
1123 | |
|
|
1124 | sub _send { |
|
|
1125 | # nop |
|
|
1126 | } |
|
|
1127 | |
|
|
1128 | sub send { |
|
|
1129 | my $cv = shift; |
|
|
1130 | $cv->{_ae_sent} = [@_]; |
|
|
1131 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
1132 | $cv->_send; |
|
|
1133 | } |
|
|
1134 | |
|
|
1135 | sub croak { |
|
|
1136 | $_[0]{_ae_croak} = $_[1]; |
|
|
1137 | $_[0]->send; |
|
|
1138 | } |
|
|
1139 | |
|
|
1140 | sub ready { |
|
|
1141 | $_[0]{_ae_sent} |
|
|
1142 | } |
|
|
1143 | |
|
|
1144 | sub _wait { |
|
|
1145 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
1146 | } |
|
|
1147 | |
|
|
1148 | sub recv { |
|
|
1149 | $_[0]->_wait; |
|
|
1150 | |
|
|
1151 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
1152 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
1153 | } |
|
|
1154 | |
|
|
1155 | sub cb { |
|
|
1156 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
1157 | $_[0]{_ae_cb} |
|
|
1158 | } |
|
|
1159 | |
|
|
1160 | sub begin { |
|
|
1161 | ++$_[0]{_ae_counter}; |
|
|
1162 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
1163 | } |
|
|
1164 | |
|
|
1165 | sub end { |
|
|
1166 | return if --$_[0]{_ae_counter}; |
|
|
1167 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
1168 | } |
|
|
1169 | |
|
|
1170 | # undocumented/compatibility with pre-3.4 |
|
|
1171 | *broadcast = \&send; |
|
|
1172 | *wait = \&_wait; |
|
|
1173 | |
488 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1174 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1175 | |
|
|
1176 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
1177 | a module. This section is only of use to event loop authors who want to |
|
|
1178 | provide AnyEvent compatibility. |
489 | |
1179 | |
490 | If you need to support another event library which isn't directly |
1180 | If you need to support another event library which isn't directly |
491 | supported by AnyEvent, you can supply your own interface to it by |
1181 | supported by AnyEvent, you can supply your own interface to it by |
492 | pushing, before the first watcher gets created, the package name of |
1182 | pushing, before the first watcher gets created, the package name of |
493 | the event module and the package name of the interface to use onto |
1183 | the event module and the package name of the interface to use onto |
494 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
1184 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
495 | AnyEvent. |
1185 | AnyEvent, so it is reasonably cheap. |
496 | |
1186 | |
497 | Example: |
1187 | Example: |
498 | |
1188 | |
499 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
1189 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
500 | |
1190 | |
501 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
1191 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
502 | package/class when it finds the C<urxvt> package/module is loaded. When |
1192 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
1193 | |
503 | AnyEvent is loaded and asked to find a suitable event model, it will |
1194 | When AnyEvent is loaded and asked to find a suitable event model, it |
504 | first check for the presence of urxvt. |
1195 | will first check for the presence of urxvt by trying to C<use> the |
|
|
1196 | C<urxvt::anyevent> module. |
505 | |
1197 | |
506 | The class should provide implementations for all watcher types (see |
1198 | The class should provide implementations for all watcher types. See |
507 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
1199 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
508 | (Source code) and so on for actual examples, use C<perldoc -m |
1200 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
509 | AnyEvent::Impl::Glib> to see the sources). |
1201 | see the sources. |
510 | |
1202 | |
|
|
1203 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
1204 | provide suitable (hopefully) replacements. |
|
|
1205 | |
511 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
1206 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
512 | uses the above line as-is. An interface isn't included in AnyEvent |
1207 | terminal emulator uses the above line as-is. An interface isn't included |
513 | because it doesn't make sense outside the embedded interpreter inside |
1208 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
514 | I<rxvt-unicode>, and it is updated and maintained as part of the |
1209 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
515 | I<rxvt-unicode> distribution. |
1210 | I<rxvt-unicode> distribution. |
516 | |
1211 | |
517 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
1212 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
518 | condition variables: code blocking while waiting for a condition will |
1213 | condition variables: code blocking while waiting for a condition will |
519 | C<die>. This still works with most modules/usages, and blocking calls must |
1214 | C<die>. This still works with most modules/usages, and blocking calls must |
520 | not be in an interactive application, so it makes sense. |
1215 | not be done in an interactive application, so it makes sense. |
521 | |
1216 | |
522 | =head1 ENVIRONMENT VARIABLES |
1217 | =head1 ENVIRONMENT VARIABLES |
523 | |
1218 | |
524 | The following environment variables are used by this module: |
1219 | The following environment variables are used by this module: |
525 | |
1220 | |
526 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
1221 | =over 4 |
527 | model gets used. |
|
|
528 | |
1222 | |
|
|
1223 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1224 | |
|
|
1225 | By default, AnyEvent will be completely silent except in fatal |
|
|
1226 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1227 | talkative. |
|
|
1228 | |
|
|
1229 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1230 | conditions, such as not being able to load the event model specified by |
|
|
1231 | C<PERL_ANYEVENT_MODEL>. |
|
|
1232 | |
|
|
1233 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1234 | model it chooses. |
|
|
1235 | |
|
|
1236 | =item C<PERL_ANYEVENT_STRICT> |
|
|
1237 | |
|
|
1238 | AnyEvent does not do much argument checking by default, as thorough |
|
|
1239 | argument checking is very costly. Setting this variable to a true value |
|
|
1240 | will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly |
|
|
1241 | check the arguments passed to most method calls. If it finds any problems |
|
|
1242 | it will croak. |
|
|
1243 | |
|
|
1244 | In other words, enables "strict" mode. |
|
|
1245 | |
|
|
1246 | Unlike C<use strict> it is definitely recommended ot keep it off in |
|
|
1247 | production. |
|
|
1248 | |
|
|
1249 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1250 | |
|
|
1251 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1252 | auto detection and -probing kicks in. It must be a string consisting |
|
|
1253 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1254 | and the resulting module name is loaded and if the load was successful, |
|
|
1255 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1256 | auto detection and -probing. |
|
|
1257 | |
|
|
1258 | This functionality might change in future versions. |
|
|
1259 | |
|
|
1260 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1261 | could start your program like this: |
|
|
1262 | |
|
|
1263 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1264 | |
|
|
1265 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1266 | |
|
|
1267 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1268 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1269 | of auto probing). |
|
|
1270 | |
|
|
1271 | Must be set to a comma-separated list of protocols or address families, |
|
|
1272 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1273 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1274 | list. |
|
|
1275 | |
|
|
1276 | This variable can effectively be used for denial-of-service attacks |
|
|
1277 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1278 | small, as the program has to handle connection errors already- |
|
|
1279 | |
|
|
1280 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1281 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1282 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1283 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1284 | IPv6, but prefer IPv6 over IPv4. |
|
|
1285 | |
|
|
1286 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1287 | |
|
|
1288 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1289 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1290 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1291 | default. |
|
|
1292 | |
|
|
1293 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1294 | EDNS0 in its DNS requests. |
|
|
1295 | |
|
|
1296 | =item C<PERL_ANYEVENT_MAX_FORKS> |
|
|
1297 | |
|
|
1298 | The maximum number of child processes that C<AnyEvent::Util::fork_call> |
|
|
1299 | will create in parallel. |
|
|
1300 | |
|
|
1301 | =back |
|
|
1302 | |
529 | =head1 EXAMPLE |
1303 | =head1 EXAMPLE PROGRAM |
530 | |
1304 | |
531 | The following program uses an io watcher to read data from stdin, a timer |
1305 | The following program uses an I/O watcher to read data from STDIN, a timer |
532 | to display a message once per second, and a condvar to exit the program |
1306 | to display a message once per second, and a condition variable to quit the |
533 | when the user enters quit: |
1307 | program when the user enters quit: |
534 | |
1308 | |
535 | use AnyEvent; |
1309 | use AnyEvent; |
536 | |
1310 | |
537 | my $cv = AnyEvent->condvar; |
1311 | my $cv = AnyEvent->condvar; |
538 | |
1312 | |
539 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
1313 | my $io_watcher = AnyEvent->io ( |
|
|
1314 | fh => \*STDIN, |
|
|
1315 | poll => 'r', |
|
|
1316 | cb => sub { |
540 | warn "io event <$_[0]>\n"; # will always output <r> |
1317 | warn "io event <$_[0]>\n"; # will always output <r> |
541 | chomp (my $input = <STDIN>); # read a line |
1318 | chomp (my $input = <STDIN>); # read a line |
542 | warn "read: $input\n"; # output what has been read |
1319 | warn "read: $input\n"; # output what has been read |
543 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1320 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
|
|
1321 | }, |
544 | }); |
1322 | ); |
545 | |
1323 | |
546 | my $time_watcher; # can only be used once |
1324 | my $time_watcher; # can only be used once |
547 | |
1325 | |
548 | sub new_timer { |
1326 | sub new_timer { |
549 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1327 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
552 | }); |
1330 | }); |
553 | } |
1331 | } |
554 | |
1332 | |
555 | new_timer; # create first timer |
1333 | new_timer; # create first timer |
556 | |
1334 | |
557 | $cv->wait; # wait until user enters /^q/i |
1335 | $cv->recv; # wait until user enters /^q/i |
558 | |
1336 | |
559 | =head1 REAL-WORLD EXAMPLE |
1337 | =head1 REAL-WORLD EXAMPLE |
560 | |
1338 | |
561 | Consider the L<Net::FCP> module. It features (among others) the following |
1339 | Consider the L<Net::FCP> module. It features (among others) the following |
562 | API calls, which are to freenet what HTTP GET requests are to http: |
1340 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
612 | syswrite $txn->{fh}, $txn->{request} |
1390 | syswrite $txn->{fh}, $txn->{request} |
613 | or die "connection or write error"; |
1391 | or die "connection or write error"; |
614 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1392 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
615 | |
1393 | |
616 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1394 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
617 | result and signals any possible waiters that the request ahs finished: |
1395 | result and signals any possible waiters that the request has finished: |
618 | |
1396 | |
619 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1397 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
620 | |
1398 | |
621 | if (end-of-file or data complete) { |
1399 | if (end-of-file or data complete) { |
622 | $txn->{result} = $txn->{buf}; |
1400 | $txn->{result} = $txn->{buf}; |
623 | $txn->{finished}->broadcast; |
1401 | $txn->{finished}->send; |
624 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1402 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
625 | } |
1403 | } |
626 | |
1404 | |
627 | The C<result> method, finally, just waits for the finished signal (if the |
1405 | The C<result> method, finally, just waits for the finished signal (if the |
628 | request was already finished, it doesn't wait, of course, and returns the |
1406 | request was already finished, it doesn't wait, of course, and returns the |
629 | data: |
1407 | data: |
630 | |
1408 | |
631 | $txn->{finished}->wait; |
1409 | $txn->{finished}->recv; |
632 | return $txn->{result}; |
1410 | return $txn->{result}; |
633 | |
1411 | |
634 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1412 | The actual code goes further and collects all errors (C<die>s, exceptions) |
635 | that occured during request processing. The C<result> method detects |
1413 | that occurred during request processing. The C<result> method detects |
636 | wether an exception as thrown (it is stored inside the $txn object) |
1414 | whether an exception as thrown (it is stored inside the $txn object) |
637 | and just throws the exception, which means connection errors and other |
1415 | and just throws the exception, which means connection errors and other |
638 | problems get reported tot he code that tries to use the result, not in a |
1416 | problems get reported tot he code that tries to use the result, not in a |
639 | random callback. |
1417 | random callback. |
640 | |
1418 | |
641 | All of this enables the following usage styles: |
1419 | All of this enables the following usage styles: |
… | |
… | |
671 | |
1449 | |
672 | my $quit = AnyEvent->condvar; |
1450 | my $quit = AnyEvent->condvar; |
673 | |
1451 | |
674 | $fcp->txn_client_get ($url)->cb (sub { |
1452 | $fcp->txn_client_get ($url)->cb (sub { |
675 | ... |
1453 | ... |
676 | $quit->broadcast; |
1454 | $quit->send; |
677 | }); |
1455 | }); |
678 | |
1456 | |
679 | $quit->wait; |
1457 | $quit->recv; |
|
|
1458 | |
|
|
1459 | |
|
|
1460 | =head1 BENCHMARKS |
|
|
1461 | |
|
|
1462 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1463 | over the event loops themselves and to give you an impression of the speed |
|
|
1464 | of various event loops I prepared some benchmarks. |
|
|
1465 | |
|
|
1466 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1467 | |
|
|
1468 | Here is a benchmark of various supported event models used natively and |
|
|
1469 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1470 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1471 | which it is), lets them fire exactly once and destroys them again. |
|
|
1472 | |
|
|
1473 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1474 | distribution. |
|
|
1475 | |
|
|
1476 | =head3 Explanation of the columns |
|
|
1477 | |
|
|
1478 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1479 | different event models feature vastly different performances, each event |
|
|
1480 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1481 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1482 | would probably take thousands of years if asked to process the same number |
|
|
1483 | of watchers as EV in this benchmark. |
|
|
1484 | |
|
|
1485 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1486 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1487 | and Perl-based overheads. |
|
|
1488 | |
|
|
1489 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1490 | takes to create a single watcher. The callback is a closure shared between |
|
|
1491 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1492 | and memory usage is not included in the figures. |
|
|
1493 | |
|
|
1494 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1495 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1496 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1497 | signal the end of this phase. |
|
|
1498 | |
|
|
1499 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1500 | watcher. |
|
|
1501 | |
|
|
1502 | =head3 Results |
|
|
1503 | |
|
|
1504 | name watchers bytes create invoke destroy comment |
|
|
1505 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1506 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1507 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1508 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1509 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1510 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1511 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1512 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1513 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1514 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1515 | |
|
|
1516 | =head3 Discussion |
|
|
1517 | |
|
|
1518 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1519 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1520 | can never compete with an event loop that uses epoll when the number of |
|
|
1521 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1522 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1523 | boost. |
|
|
1524 | |
|
|
1525 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1526 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1527 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1528 | higher number of watchers at a disadvantage. |
|
|
1529 | |
|
|
1530 | To put the range of results into perspective, consider that on the |
|
|
1531 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1532 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1533 | cycles with POE. |
|
|
1534 | |
|
|
1535 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1536 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1537 | far less memory than any other event loop and is still faster than Event |
|
|
1538 | natively. |
|
|
1539 | |
|
|
1540 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1541 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1542 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1543 | adds very little overhead in itself. Like any select-based backend its |
|
|
1544 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1545 | them active), of course, but this was not subject of this benchmark. |
|
|
1546 | |
|
|
1547 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1548 | cost, but overall scores in on the third place. |
|
|
1549 | |
|
|
1550 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1551 | faster callback invocation and overall ends up in the same class as |
|
|
1552 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1553 | watchers increases the processing time by more than a factor of four, |
|
|
1554 | making it completely unusable when using larger numbers of watchers |
|
|
1555 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1556 | inefficiencies of C<poll> do not account for this). |
|
|
1557 | |
|
|
1558 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1559 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1560 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1561 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1562 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1563 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1564 | above). |
|
|
1565 | |
|
|
1566 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1567 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1568 | be tested because it wasn't working) shows abysmal performance and |
|
|
1569 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1570 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1571 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1572 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1573 | implementation. |
|
|
1574 | |
|
|
1575 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1576 | for the performance issues, though, as session creation overhead is |
|
|
1577 | small compared to execution of the state machine, which is coded pretty |
|
|
1578 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1579 | using multiple sessions is not a good approach, especially regarding |
|
|
1580 | memory usage, even the author of POE could not come up with a faster |
|
|
1581 | design). |
|
|
1582 | |
|
|
1583 | =head3 Summary |
|
|
1584 | |
|
|
1585 | =over 4 |
|
|
1586 | |
|
|
1587 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1588 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1589 | performance with or without AnyEvent. |
|
|
1590 | |
|
|
1591 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1592 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1593 | adds AnyEvent significant overhead. |
|
|
1594 | |
|
|
1595 | =item * You should avoid POE like the plague if you want performance or |
|
|
1596 | reasonable memory usage. |
|
|
1597 | |
|
|
1598 | =back |
|
|
1599 | |
|
|
1600 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1601 | |
|
|
1602 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1603 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1604 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1605 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1606 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1607 | |
|
|
1608 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1609 | are active at any one point (so there is a constant number of active |
|
|
1610 | fds for each loop iteration, but which fds these are is random). The |
|
|
1611 | timeout is reset each time something is read because that reflects how |
|
|
1612 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1613 | |
|
|
1614 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1615 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1616 | connections, most of which are idle at any one point in time. |
|
|
1617 | |
|
|
1618 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1619 | distribution. |
|
|
1620 | |
|
|
1621 | =head3 Explanation of the columns |
|
|
1622 | |
|
|
1623 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1624 | each server has a read and write socket end). |
|
|
1625 | |
|
|
1626 | I<create> is the time it takes to create a socket pair (which is |
|
|
1627 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1628 | |
|
|
1629 | I<request>, the most important value, is the time it takes to handle a |
|
|
1630 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1631 | it to another server. This includes deleting the old timeout and creating |
|
|
1632 | a new one that moves the timeout into the future. |
|
|
1633 | |
|
|
1634 | =head3 Results |
|
|
1635 | |
|
|
1636 | name sockets create request |
|
|
1637 | EV 20000 69.01 11.16 |
|
|
1638 | Perl 20000 73.32 35.87 |
|
|
1639 | Event 20000 212.62 257.32 |
|
|
1640 | Glib 20000 651.16 1896.30 |
|
|
1641 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1642 | |
|
|
1643 | =head3 Discussion |
|
|
1644 | |
|
|
1645 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1646 | particular event loop. |
|
|
1647 | |
|
|
1648 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1649 | is relatively high, though. |
|
|
1650 | |
|
|
1651 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1652 | loops Event and Glib. |
|
|
1653 | |
|
|
1654 | Event suffers from high setup time as well (look at its code and you will |
|
|
1655 | understand why). Callback invocation also has a high overhead compared to |
|
|
1656 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1657 | uses select or poll in basically all documented configurations. |
|
|
1658 | |
|
|
1659 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1660 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1661 | |
|
|
1662 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1663 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1664 | it uses a C-based event loop in this case. |
|
|
1665 | |
|
|
1666 | =head3 Summary |
|
|
1667 | |
|
|
1668 | =over 4 |
|
|
1669 | |
|
|
1670 | =item * The pure perl implementation performs extremely well. |
|
|
1671 | |
|
|
1672 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1673 | |
|
|
1674 | =back |
|
|
1675 | |
|
|
1676 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1677 | |
|
|
1678 | While event loops should scale (and select-based ones do not...) even to |
|
|
1679 | large servers, most programs we (or I :) actually write have only a few |
|
|
1680 | I/O watchers. |
|
|
1681 | |
|
|
1682 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1683 | case, but it uses only eight "servers", of which three are active at any |
|
|
1684 | one time. This should reflect performance for a small server relatively |
|
|
1685 | well. |
|
|
1686 | |
|
|
1687 | The columns are identical to the previous table. |
|
|
1688 | |
|
|
1689 | =head3 Results |
|
|
1690 | |
|
|
1691 | name sockets create request |
|
|
1692 | EV 16 20.00 6.54 |
|
|
1693 | Perl 16 25.75 12.62 |
|
|
1694 | Event 16 81.27 35.86 |
|
|
1695 | Glib 16 32.63 15.48 |
|
|
1696 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1697 | |
|
|
1698 | =head3 Discussion |
|
|
1699 | |
|
|
1700 | The benchmark tries to test the performance of a typical small |
|
|
1701 | server. While knowing how various event loops perform is interesting, keep |
|
|
1702 | in mind that their overhead in this case is usually not as important, due |
|
|
1703 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1704 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1705 | them). |
|
|
1706 | |
|
|
1707 | EV is again fastest. |
|
|
1708 | |
|
|
1709 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1710 | loops Event and Glib, although the difference is too small to really |
|
|
1711 | matter. |
|
|
1712 | |
|
|
1713 | POE also performs much better in this case, but is is still far behind the |
|
|
1714 | others. |
|
|
1715 | |
|
|
1716 | =head3 Summary |
|
|
1717 | |
|
|
1718 | =over 4 |
|
|
1719 | |
|
|
1720 | =item * C-based event loops perform very well with small number of |
|
|
1721 | watchers, as the management overhead dominates. |
|
|
1722 | |
|
|
1723 | =back |
|
|
1724 | |
|
|
1725 | |
|
|
1726 | =head1 FORK |
|
|
1727 | |
|
|
1728 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1729 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1730 | calls. Only L<EV> is fully fork-aware. |
|
|
1731 | |
|
|
1732 | If you have to fork, you must either do so I<before> creating your first |
|
|
1733 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1734 | |
|
|
1735 | |
|
|
1736 | =head1 SECURITY CONSIDERATIONS |
|
|
1737 | |
|
|
1738 | AnyEvent can be forced to load any event model via |
|
|
1739 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1740 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1741 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1742 | will not be active when the program uses a different event model than |
|
|
1743 | specified in the variable. |
|
|
1744 | |
|
|
1745 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1746 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1747 | |
|
|
1748 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1749 | |
|
|
1750 | use AnyEvent; |
|
|
1751 | |
|
|
1752 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1753 | be used to probe what backend is used and gain other information (which is |
|
|
1754 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and |
|
|
1755 | $ENV{PERL_ANYEGENT_STRICT}. |
|
|
1756 | |
|
|
1757 | |
|
|
1758 | =head1 BUGS |
|
|
1759 | |
|
|
1760 | Perl 5.8 has numerous memleaks that sometimes hit this module and are hard |
|
|
1761 | to work around. If you suffer from memleaks, first upgrade to Perl 5.10 |
|
|
1762 | and check wether the leaks still show up. (Perl 5.10.0 has other annoying |
|
|
1763 | mamleaks, such as leaking on C<map> and C<grep> but it is usually not as |
|
|
1764 | pronounced). |
|
|
1765 | |
680 | |
1766 | |
681 | =head1 SEE ALSO |
1767 | =head1 SEE ALSO |
682 | |
1768 | |
683 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1769 | Utility functions: L<AnyEvent::Util>. |
684 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
|
|
685 | |
1770 | |
686 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
1771 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
|
|
1772 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
|
|
1773 | |
687 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
1774 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
688 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
1775 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
1776 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
1777 | L<AnyEvent::Impl::POE>. |
689 | |
1778 | |
|
|
1779 | Non-blocking file handles, sockets, TCP clients and |
|
|
1780 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1781 | |
|
|
1782 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1783 | |
|
|
1784 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1785 | |
690 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
1786 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
691 | |
1787 | |
692 | =head1 |
1788 | |
|
|
1789 | =head1 AUTHOR |
|
|
1790 | |
|
|
1791 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1792 | http://home.schmorp.de/ |
693 | |
1793 | |
694 | =cut |
1794 | =cut |
695 | |
1795 | |
696 | 1 |
1796 | 1 |
697 | |
1797 | |