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 | |
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14 | |
14 | |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
16 | ... |
16 | ... |
17 | }); |
17 | }); |
18 | |
18 | |
19 | my $w = AnyEvent->condvar; # stores wether a condition was flagged |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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20 | $w->send; # wake up current and all future recv's |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
21 | $w->recv; # enters "main loop" till $condvar gets ->send |
21 | $w->broadcast; # wake up current and all future wait's |
22 | |
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23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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24 | |
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25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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26 | nowadays. So what is different about AnyEvent? |
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27 | |
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28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
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29 | policy> and AnyEvent is I<small and efficient>. |
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30 | |
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31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
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32 | interfaces to whatever event model the main program happens to use in a |
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33 | pragmatic way. For event models and certain classes of immortals alike, |
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34 | the statement "there can only be one" is a bitter reality: In general, |
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35 | only one event loop can be active at the same time in a process. AnyEvent |
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36 | helps hiding the differences between those event loops. |
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37 | |
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38 | The goal of AnyEvent is to offer module authors the ability to do event |
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39 | programming (waiting for I/O or timer events) without subscribing to a |
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40 | religion, a way of living, and most importantly: without forcing your |
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41 | module users into the same thing by forcing them to use the same event |
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42 | model you use. |
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43 | |
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44 | For modules like POE or IO::Async (which is a total misnomer as it is |
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45 | actually doing all I/O I<synchronously>...), using them in your module is |
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46 | like joining a cult: After you joined, you are dependent on them and you |
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47 | cannot use anything else, as it is simply incompatible to everything that |
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48 | isn't itself. What's worse, all the potential users of your module are |
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49 | I<also> forced to use the same event loop you use. |
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50 | |
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51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
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52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
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53 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if |
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54 | your module uses one of those, every user of your module has to use it, |
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55 | too. But if your module uses AnyEvent, it works transparently with all |
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56 | event models it supports (including stuff like POE and IO::Async, as long |
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57 | as those use one of the supported event loops. It is trivial to add new |
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58 | event loops to AnyEvent, too, so it is future-proof). |
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59 | |
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60 | In addition to being free of having to use I<the one and only true event |
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61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
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62 | modules, you get an enormous amount of code and strict rules you have to |
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63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
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64 | offering the functionality that is necessary, in as thin as a wrapper as |
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65 | technically possible. |
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66 | |
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67 | Of course, if you want lots of policy (this can arguably be somewhat |
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68 | useful) and you want to force your users to use the one and only event |
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69 | model, you should I<not> use this module. |
22 | |
70 | |
23 | =head1 DESCRIPTION |
71 | =head1 DESCRIPTION |
24 | |
72 | |
25 | L<AnyEvent> provides an identical interface to multiple event loops. This |
73 | L<AnyEvent> provides an identical interface to multiple event loops. This |
26 | allows module authors to utilise an event loop without forcing module |
74 | allows module authors to utilise an event loop without forcing module |
27 | users to use the same event loop (as only a single event loop can coexist |
75 | users to use the same event loop (as only a single event loop can coexist |
28 | peacefully at any one time). |
76 | peacefully at any one time). |
29 | |
77 | |
30 | The interface itself is vaguely similar but not identical to the Event |
78 | The interface itself is vaguely similar, but not identical to the L<Event> |
31 | module. |
79 | module. |
32 | |
80 | |
33 | On the first call of any method, the module tries to detect the currently |
81 | During the first call of any watcher-creation method, the module tries |
34 | loaded event loop by probing wether any of the following modules is |
82 | to detect the currently loaded event loop by probing whether one of the |
35 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
83 | following modules is already loaded: L<EV>, |
36 | used. If none is found, the module tries to load these modules in the |
84 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
37 | order given. The first one that could be successfully loaded will be |
85 | L<POE>. The first one found is used. If none are found, the module tries |
38 | used. If still none could be found, AnyEvent will fall back to a pure-perl |
86 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
39 | event loop, which is also not very efficient. |
87 | adaptor should always succeed) in the order given. The first one that can |
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88 | be successfully loaded will be used. If, after this, still none could be |
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89 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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90 | very efficient, but should work everywhere. |
40 | |
91 | |
41 | Because AnyEvent first checks for modules that are already loaded, loading |
92 | Because AnyEvent first checks for modules that are already loaded, loading |
42 | an Event model explicitly before first using AnyEvent will likely make |
93 | an event model explicitly before first using AnyEvent will likely make |
43 | that model the default. For example: |
94 | that model the default. For example: |
44 | |
95 | |
45 | use Tk; |
96 | use Tk; |
46 | use AnyEvent; |
97 | use AnyEvent; |
47 | |
98 | |
48 | # .. AnyEvent will likely default to Tk |
99 | # .. AnyEvent will likely default to Tk |
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100 | |
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101 | The I<likely> means that, if any module loads another event model and |
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102 | starts using it, all bets are off. Maybe you should tell their authors to |
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103 | use AnyEvent so their modules work together with others seamlessly... |
49 | |
104 | |
50 | The pure-perl implementation of AnyEvent is called |
105 | The pure-perl implementation of AnyEvent is called |
51 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
106 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
52 | explicitly. |
107 | explicitly. |
53 | |
108 | |
54 | =head1 WATCHERS |
109 | =head1 WATCHERS |
55 | |
110 | |
56 | AnyEvent has the central concept of a I<watcher>, which is an object that |
111 | AnyEvent has the central concept of a I<watcher>, which is an object that |
57 | stores relevant data for each kind of event you are waiting for, such as |
112 | stores relevant data for each kind of event you are waiting for, such as |
58 | the callback to call, the filehandle to watch, etc. |
113 | the callback to call, the file handle to watch, etc. |
59 | |
114 | |
60 | These watchers are normal Perl objects with normal Perl lifetime. After |
115 | These watchers are normal Perl objects with normal Perl lifetime. After |
61 | creating a watcher it will immediately "watch" for events and invoke |
116 | creating a watcher it will immediately "watch" for events and invoke the |
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117 | callback when the event occurs (of course, only when the event model |
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118 | is in control). |
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119 | |
62 | the callback. To disable the watcher you have to destroy it (e.g. by |
120 | To disable the watcher you have to destroy it (e.g. by setting the |
63 | setting the variable that stores it to C<undef> or otherwise deleting all |
121 | variable you store it in to C<undef> or otherwise deleting all references |
64 | references to it). |
122 | to it). |
65 | |
123 | |
66 | All watchers are created by calling a method on the C<AnyEvent> class. |
124 | All watchers are created by calling a method on the C<AnyEvent> class. |
67 | |
125 | |
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126 | Many watchers either are used with "recursion" (repeating timers for |
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127 | example), or need to refer to their watcher object in other ways. |
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128 | |
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129 | An any way to achieve that is this pattern: |
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130 | |
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131 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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132 | # you can use $w here, for example to undef it |
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133 | undef $w; |
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134 | }); |
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135 | |
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136 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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137 | my variables are only visible after the statement in which they are |
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138 | declared. |
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139 | |
68 | =head2 IO WATCHERS |
140 | =head2 I/O WATCHERS |
69 | |
141 | |
70 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
142 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
71 | the following mandatory arguments: |
143 | with the following mandatory key-value pairs as arguments: |
72 | |
144 | |
73 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
145 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch |
74 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
146 | for events. C<poll> must be a string that is either C<r> or C<w>, |
75 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback |
147 | which creates a watcher waiting for "r"eadable or "w"ritable events, |
76 | to invoke everytime the filehandle becomes ready. |
148 | respectively. C<cb> is the callback to invoke each time the file handle |
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149 | becomes ready. |
77 | |
150 | |
78 | Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
151 | Although the callback might get passed parameters, their value and |
79 | a socket you can have one r + one w, not any more (limitation comes from |
152 | presence is undefined and you cannot rely on them. Portable AnyEvent |
80 | Tk - if you are sure you are not using Tk this limitation is gone). |
153 | callbacks cannot use arguments passed to I/O watcher callbacks. |
81 | |
154 | |
82 | Filehandles will be kept alive, so as long as the watcher exists, the |
155 | The I/O watcher might use the underlying file descriptor or a copy of it. |
83 | filehandle exists, too. |
156 | You must not close a file handle as long as any watcher is active on the |
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157 | underlying file descriptor. |
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158 | |
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159 | Some event loops issue spurious readyness notifications, so you should |
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160 | always use non-blocking calls when reading/writing from/to your file |
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161 | handles. |
84 | |
162 | |
85 | Example: |
163 | Example: |
86 | |
164 | |
87 | # wait for readability of STDIN, then read a line and disable the watcher |
165 | # wait for readability of STDIN, then read a line and disable the watcher |
88 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
166 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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94 | =head2 TIME WATCHERS |
172 | =head2 TIME WATCHERS |
95 | |
173 | |
96 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
174 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
97 | method with the following mandatory arguments: |
175 | method with the following mandatory arguments: |
98 | |
176 | |
99 | C<after> after how many seconds (fractions are supported) should the timer |
177 | C<after> specifies after how many seconds (fractional values are |
100 | activate. C<cb> the callback to invoke. |
178 | supported) the callback should be invoked. C<cb> is the callback to invoke |
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179 | in that case. |
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180 | |
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181 | Although the callback might get passed parameters, their value and |
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182 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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183 | callbacks cannot use arguments passed to time watcher callbacks. |
101 | |
184 | |
102 | The timer callback will be invoked at most once: if you want a repeating |
185 | The timer callback will be invoked at most once: if you want a repeating |
103 | timer you have to create a new watcher (this is a limitation by both Tk |
186 | timer you have to create a new watcher (this is a limitation by both Tk |
104 | and Glib). |
187 | and Glib). |
105 | |
188 | |
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109 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
192 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
110 | warn "timeout\n"; |
193 | warn "timeout\n"; |
111 | }); |
194 | }); |
112 | |
195 | |
113 | # to cancel the timer: |
196 | # to cancel the timer: |
114 | undef $w |
197 | undef $w; |
115 | |
198 | |
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199 | Example 2: |
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200 | |
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201 | # fire an event after 0.5 seconds, then roughly every second |
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202 | my $w; |
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203 | |
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204 | my $cb = sub { |
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205 | # cancel the old timer while creating a new one |
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206 | $w = AnyEvent->timer (after => 1, cb => $cb); |
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207 | }; |
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208 | |
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209 | # start the "loop" by creating the first watcher |
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210 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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211 | |
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212 | =head3 TIMING ISSUES |
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213 | |
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214 | There are two ways to handle timers: based on real time (relative, "fire |
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215 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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216 | o'clock"). |
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217 | |
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218 | While most event loops expect timers to specified in a relative way, they |
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219 | use absolute time internally. This makes a difference when your clock |
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220 | "jumps", for example, when ntp decides to set your clock backwards from |
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221 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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222 | fire "after" a second might actually take six years to finally fire. |
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223 | |
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224 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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225 | about these issues is L<EV>, which offers both relative (ev_timer, based |
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226 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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227 | timers. |
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228 | |
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229 | AnyEvent always prefers relative timers, if available, matching the |
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230 | AnyEvent API. |
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231 | |
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232 | =head2 SIGNAL WATCHERS |
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233 | |
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234 | You can watch for signals using a signal watcher, C<signal> is the signal |
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235 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
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236 | be invoked whenever a signal occurs. |
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237 | |
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238 | Although the callback might get passed parameters, their value and |
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239 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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240 | callbacks cannot use arguments passed to signal watcher callbacks. |
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241 | |
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242 | Multiple signal occurrences can be clumped together into one callback |
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243 | invocation, and callback invocation will be synchronous. Synchronous means |
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244 | that it might take a while until the signal gets handled by the process, |
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245 | but it is guaranteed not to interrupt any other callbacks. |
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246 | |
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247 | The main advantage of using these watchers is that you can share a signal |
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248 | between multiple watchers. |
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249 | |
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250 | This watcher might use C<%SIG>, so programs overwriting those signals |
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251 | directly will likely not work correctly. |
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252 | |
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253 | Example: exit on SIGINT |
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254 | |
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255 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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256 | |
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257 | =head2 CHILD PROCESS WATCHERS |
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258 | |
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259 | You can also watch on a child process exit and catch its exit status. |
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260 | |
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261 | The child process is specified by the C<pid> argument (if set to C<0>, it |
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262 | watches for any child process exit). The watcher will trigger as often |
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263 | as status change for the child are received. This works by installing a |
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264 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
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265 | and exit status (as returned by waitpid), so unlike other watcher types, |
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266 | you I<can> rely on child watcher callback arguments. |
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267 | |
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268 | There is a slight catch to child watchers, however: you usually start them |
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269 | I<after> the child process was created, and this means the process could |
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270 | have exited already (and no SIGCHLD will be sent anymore). |
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271 | |
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272 | Not all event models handle this correctly (POE doesn't), but even for |
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273 | event models that I<do> handle this correctly, they usually need to be |
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274 | loaded before the process exits (i.e. before you fork in the first place). |
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275 | |
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276 | This means you cannot create a child watcher as the very first thing in an |
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277 | AnyEvent program, you I<have> to create at least one watcher before you |
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278 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
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279 | |
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280 | Example: fork a process and wait for it |
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281 | |
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282 | my $done = AnyEvent->condvar; |
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283 | |
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284 | my $pid = fork or exit 5; |
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285 | |
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286 | my $w = AnyEvent->child ( |
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287 | pid => $pid, |
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288 | cb => sub { |
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289 | my ($pid, $status) = @_; |
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290 | warn "pid $pid exited with status $status"; |
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291 | $done->send; |
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292 | }, |
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293 | ); |
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294 | |
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295 | # do something else, then wait for process exit |
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296 | $done->recv; |
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297 | |
116 | =head2 CONDITION WATCHERS |
298 | =head2 CONDITION VARIABLES |
117 | |
299 | |
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300 | If you are familiar with some event loops you will know that all of them |
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301 | require you to run some blocking "loop", "run" or similar function that |
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302 | will actively watch for new events and call your callbacks. |
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303 | |
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304 | AnyEvent is different, it expects somebody else to run the event loop and |
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305 | will only block when necessary (usually when told by the user). |
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306 | |
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307 | The instrument to do that is called a "condition variable", so called |
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308 | because they represent a condition that must become true. |
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309 | |
118 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
310 | Condition variables can be created by calling the C<< AnyEvent->condvar |
119 | method without any arguments. |
311 | >> method, usually without arguments. The only argument pair allowed is |
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312 | C<cb>, which specifies a callback to be called when the condition variable |
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313 | becomes true. |
120 | |
314 | |
121 | A condition watcher watches for a condition - precisely that the C<< |
315 | After creation, the condition variable is "false" until it becomes "true" |
122 | ->broadcast >> method has been called. |
316 | by calling the C<send> method. |
123 | |
317 | |
124 | The watcher has only two methods: |
318 | Condition variables are similar to callbacks, except that you can |
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319 | optionally wait for them. They can also be called merge points - points |
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320 | in time where multiple outstanding events have been processed. And yet |
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321 | another way to call them is transactions - each condition variable can be |
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322 | used to represent a transaction, which finishes at some point and delivers |
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323 | a result. |
125 | |
324 | |
126 | =over 4 |
325 | Condition variables are very useful to signal that something has finished, |
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326 | for example, if you write a module that does asynchronous http requests, |
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327 | then a condition variable would be the ideal candidate to signal the |
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328 | availability of results. The user can either act when the callback is |
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329 | called or can synchronously C<< ->recv >> for the results. |
127 | |
330 | |
128 | =item $cv->wait |
331 | You can also use them to simulate traditional event loops - for example, |
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332 | you can block your main program until an event occurs - for example, you |
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333 | could C<< ->recv >> in your main program until the user clicks the Quit |
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334 | button of your app, which would C<< ->send >> the "quit" event. |
129 | |
335 | |
130 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
336 | Note that condition variables recurse into the event loop - if you have |
131 | called on c<$cv>, while servicing other watchers normally. |
337 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
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338 | lose. Therefore, condition variables are good to export to your caller, but |
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339 | you should avoid making a blocking wait yourself, at least in callbacks, |
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340 | as this asks for trouble. |
132 | |
341 | |
133 | Not all event models support a blocking wait - some die in that case, so |
342 | Condition variables are represented by hash refs in perl, and the keys |
134 | if you are using this from a module, never require a blocking wait, but |
343 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
135 | let the caller decide wether the call will block or not (for example, |
344 | easy (it is often useful to build your own transaction class on top of |
136 | by coupling condition variables with some kind of request results and |
345 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
137 | supporting callbacks so the caller knows that getting the result will not |
346 | it's C<new> method in your own C<new> method. |
138 | block, while still suppporting blockign waits if the caller so desires). |
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139 | |
347 | |
140 | You can only wait once on a condition - additional calls will return |
348 | There are two "sides" to a condition variable - the "producer side" which |
141 | immediately. |
349 | eventually calls C<< -> send >>, and the "consumer side", which waits |
142 | |
350 | for the send to occur. |
143 | =item $cv->broadcast |
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144 | |
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145 | Flag the condition as ready - a running C<< ->wait >> and all further |
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146 | calls to C<wait> will return after this method has been called. If nobody |
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147 | is waiting the broadcast will be remembered.. |
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148 | |
351 | |
149 | Example: |
352 | Example: |
150 | |
353 | |
151 | # wait till the result is ready |
354 | # wait till the result is ready |
152 | my $result_ready = AnyEvent->condvar; |
355 | my $result_ready = AnyEvent->condvar; |
153 | |
356 | |
154 | # do something such as adding a timer |
357 | # do something such as adding a timer |
155 | # or socket watcher the calls $result_ready->broadcast |
358 | # or socket watcher the calls $result_ready->send |
156 | # when the "result" is ready. |
359 | # when the "result" is ready. |
|
|
360 | # in this case, we simply use a timer: |
|
|
361 | my $w = AnyEvent->timer ( |
|
|
362 | after => 1, |
|
|
363 | cb => sub { $result_ready->send }, |
|
|
364 | ); |
157 | |
365 | |
|
|
366 | # this "blocks" (while handling events) till the callback |
|
|
367 | # calls send |
158 | $result_ready->wait; |
368 | $result_ready->recv; |
|
|
369 | |
|
|
370 | =head3 METHODS FOR PRODUCERS |
|
|
371 | |
|
|
372 | These methods should only be used by the producing side, i.e. the |
|
|
373 | code/module that eventually sends the signal. Note that it is also |
|
|
374 | the producer side which creates the condvar in most cases, but it isn't |
|
|
375 | uncommon for the consumer to create it as well. |
|
|
376 | |
|
|
377 | =over 4 |
|
|
378 | |
|
|
379 | =item $cv->send (...) |
|
|
380 | |
|
|
381 | Flag the condition as ready - a running C<< ->recv >> and all further |
|
|
382 | calls to C<recv> will (eventually) return after this method has been |
|
|
383 | called. If nobody is waiting the send will be remembered. |
|
|
384 | |
|
|
385 | If a callback has been set on the condition variable, it is called |
|
|
386 | immediately from within send. |
|
|
387 | |
|
|
388 | Any arguments passed to the C<send> call will be returned by all |
|
|
389 | future C<< ->recv >> calls. |
|
|
390 | |
|
|
391 | =item $cv->croak ($error) |
|
|
392 | |
|
|
393 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
|
|
394 | C<Carp::croak> with the given error message/object/scalar. |
|
|
395 | |
|
|
396 | This can be used to signal any errors to the condition variable |
|
|
397 | user/consumer. |
|
|
398 | |
|
|
399 | =item $cv->begin ([group callback]) |
|
|
400 | |
|
|
401 | =item $cv->end |
|
|
402 | |
|
|
403 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
404 | |
|
|
405 | These two methods can be used to combine many transactions/events into |
|
|
406 | one. For example, a function that pings many hosts in parallel might want |
|
|
407 | to use a condition variable for the whole process. |
|
|
408 | |
|
|
409 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
410 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
411 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
412 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
413 | callback was set, C<send> will be called without any arguments. |
|
|
414 | |
|
|
415 | Let's clarify this with the ping example: |
|
|
416 | |
|
|
417 | my $cv = AnyEvent->condvar; |
|
|
418 | |
|
|
419 | my %result; |
|
|
420 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
421 | |
|
|
422 | for my $host (@list_of_hosts) { |
|
|
423 | $cv->begin; |
|
|
424 | ping_host_then_call_callback $host, sub { |
|
|
425 | $result{$host} = ...; |
|
|
426 | $cv->end; |
|
|
427 | }; |
|
|
428 | } |
|
|
429 | |
|
|
430 | $cv->end; |
|
|
431 | |
|
|
432 | This code fragment supposedly pings a number of hosts and calls |
|
|
433 | C<send> after results for all then have have been gathered - in any |
|
|
434 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
435 | each ping request and calls C<end> when it has received some result for |
|
|
436 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
437 | results arrive is not relevant. |
|
|
438 | |
|
|
439 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
440 | loop, which serves two important purposes: first, it sets the callback |
|
|
441 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
442 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
443 | doesn't execute once). |
|
|
444 | |
|
|
445 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
446 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
447 | is called at least once, and then, for each subrequest you start, call |
|
|
448 | C<begin> and for each subrequest you finish, call C<end>. |
159 | |
449 | |
160 | =back |
450 | =back |
161 | |
451 | |
162 | =head2 SIGNAL WATCHERS |
452 | =head3 METHODS FOR CONSUMERS |
163 | |
453 | |
164 | You can listen for signals using a signal watcher, C<signal> is the signal |
454 | These methods should only be used by the consuming side, i.e. the |
165 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
455 | code awaits the condition. |
166 | together into one callback invocation, and callback invocation might or |
|
|
167 | might not be asynchronous. |
|
|
168 | |
456 | |
169 | These watchers might use C<%SIG>, so programs overwriting those signals |
457 | =over 4 |
170 | directly will likely not work correctly. |
|
|
171 | |
458 | |
172 | Example: exit on SIGINT |
459 | =item $cv->recv |
173 | |
460 | |
174 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
461 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
|
|
462 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
463 | normally. |
175 | |
464 | |
176 | =head2 CHILD PROCESS WATCHERS |
465 | You can only wait once on a condition - additional calls are valid but |
|
|
466 | will return immediately. |
177 | |
467 | |
178 | You can also listen for the status of a child process specified by the |
468 | If an error condition has been set by calling C<< ->croak >>, then this |
179 | C<pid> argument. The watcher will only trigger once. This works by |
469 | function will call C<croak>. |
180 | installing a signal handler for C<SIGCHLD>. |
|
|
181 | |
470 | |
182 | Example: wait for pid 1333 |
471 | In list context, all parameters passed to C<send> will be returned, |
|
|
472 | in scalar context only the first one will be returned. |
183 | |
473 | |
184 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
474 | Not all event models support a blocking wait - some die in that case |
|
|
475 | (programs might want to do that to stay interactive), so I<if you are |
|
|
476 | using this from a module, never require a blocking wait>, but let the |
|
|
477 | caller decide whether the call will block or not (for example, by coupling |
|
|
478 | condition variables with some kind of request results and supporting |
|
|
479 | callbacks so the caller knows that getting the result will not block, |
|
|
480 | while still supporting blocking waits if the caller so desires). |
185 | |
481 | |
186 | =head1 GLOBALS |
482 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
|
|
483 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
|
|
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
|
|
485 | can supply. |
|
|
486 | |
|
|
487 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
488 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
489 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
490 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
491 | coroutine (one that doesn't run the event loop). |
|
|
492 | |
|
|
493 | You can ensure that C<< -recv >> never blocks by setting a callback and |
|
|
494 | only calling C<< ->recv >> from within that callback (or at a later |
|
|
495 | time). This will work even when the event loop does not support blocking |
|
|
496 | waits otherwise. |
|
|
497 | |
|
|
498 | =item $bool = $cv->ready |
|
|
499 | |
|
|
500 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
501 | C<croak> have been called. |
|
|
502 | |
|
|
503 | =item $cb = $cv->cb ([new callback]) |
|
|
504 | |
|
|
505 | This is a mutator function that returns the callback set and optionally |
|
|
506 | replaces it before doing so. |
|
|
507 | |
|
|
508 | The callback will be called when the condition becomes "true", i.e. when |
|
|
509 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
|
|
510 | or at any later time is guaranteed not to block. |
|
|
511 | |
|
|
512 | =back |
|
|
513 | |
|
|
514 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
187 | |
515 | |
188 | =over 4 |
516 | =over 4 |
189 | |
517 | |
190 | =item $AnyEvent::MODEL |
518 | =item $AnyEvent::MODEL |
191 | |
519 | |
… | |
… | |
195 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
523 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
196 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
524 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
197 | |
525 | |
198 | The known classes so far are: |
526 | The known classes so far are: |
199 | |
527 | |
200 | AnyEvent::Impl::Coro based on Coro::Event, best choise. |
528 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
201 | AnyEvent::Impl::Event based on Event, also best choice :) |
529 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
530 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
202 | AnyEvent::Impl::Glib based on Glib, second-best choice. |
531 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
203 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
532 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
204 | AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
533 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
534 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
535 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
536 | |
|
|
537 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
538 | watching file handles. However, you can use WxWidgets through the |
|
|
539 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
540 | second, which was considered to be too horrible to even consider for |
|
|
541 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
542 | it's adaptor. |
|
|
543 | |
|
|
544 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
545 | autodetecting them. |
205 | |
546 | |
206 | =item AnyEvent::detect |
547 | =item AnyEvent::detect |
207 | |
548 | |
208 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
549 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
209 | necessary. You should only call this function right before you would have |
550 | if necessary. You should only call this function right before you would |
210 | created an AnyEvent watcher anyway, that is, very late at runtime. |
551 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
552 | runtime. |
|
|
553 | |
|
|
554 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
555 | |
|
|
556 | Arranges for the code block to be executed as soon as the event model is |
|
|
557 | autodetected (or immediately if this has already happened). |
|
|
558 | |
|
|
559 | If called in scalar or list context, then it creates and returns an object |
|
|
560 | that automatically removes the callback again when it is destroyed. See |
|
|
561 | L<Coro::BDB> for a case where this is useful. |
|
|
562 | |
|
|
563 | =item @AnyEvent::post_detect |
|
|
564 | |
|
|
565 | If there are any code references in this array (you can C<push> to it |
|
|
566 | before or after loading AnyEvent), then they will called directly after |
|
|
567 | the event loop has been chosen. |
|
|
568 | |
|
|
569 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
570 | if it contains a true value then the event loop has already been detected, |
|
|
571 | and the array will be ignored. |
|
|
572 | |
|
|
573 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
211 | |
574 | |
212 | =back |
575 | =back |
213 | |
576 | |
214 | =head1 WHAT TO DO IN A MODULE |
577 | =head1 WHAT TO DO IN A MODULE |
215 | |
578 | |
216 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
579 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
217 | freely, but you should not load a specific event module or rely on it. |
580 | freely, but you should not load a specific event module or rely on it. |
218 | |
581 | |
219 | Be careful when you create watchers in the module body - Anyevent will |
582 | Be careful when you create watchers in the module body - AnyEvent will |
220 | decide which event module to use as soon as the first method is called, so |
583 | decide which event module to use as soon as the first method is called, so |
221 | by calling AnyEvent in your module body you force the user of your module |
584 | by calling AnyEvent in your module body you force the user of your module |
222 | to load the event module first. |
585 | to load the event module first. |
223 | |
586 | |
|
|
587 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
|
|
588 | the C<< ->send >> method has been called on it already. This is |
|
|
589 | because it will stall the whole program, and the whole point of using |
|
|
590 | events is to stay interactive. |
|
|
591 | |
|
|
592 | It is fine, however, to call C<< ->recv >> when the user of your module |
|
|
593 | requests it (i.e. if you create a http request object ad have a method |
|
|
594 | called C<results> that returns the results, it should call C<< ->recv >> |
|
|
595 | freely, as the user of your module knows what she is doing. always). |
|
|
596 | |
224 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
597 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
225 | |
598 | |
226 | There will always be a single main program - the only place that should |
599 | There will always be a single main program - the only place that should |
227 | dictate which event model to use. |
600 | dictate which event model to use. |
228 | |
601 | |
229 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
602 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
230 | do anything special and let AnyEvent decide which implementation to chose. |
603 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
604 | decide which implementation to chose if some module relies on it. |
231 | |
605 | |
232 | If the main program relies on a specific event model (for example, in Gtk2 |
606 | If the main program relies on a specific event model. For example, in |
233 | programs you have to rely on either Glib or Glib::Event), you should load |
607 | Gtk2 programs you have to rely on the Glib module. You should load the |
234 | it before loading AnyEvent or any module that uses it, generally, as early |
608 | event module before loading AnyEvent or any module that uses it: generally |
235 | as possible. The reason is that modules might create watchers when they |
609 | speaking, you should load it as early as possible. The reason is that |
236 | are loaded, and AnyEvent will decide on the event model to use as soon as |
610 | modules might create watchers when they are loaded, and AnyEvent will |
237 | it creates watchers, and it might chose the wrong one unless you load the |
611 | decide on the event model to use as soon as it creates watchers, and it |
238 | correct one yourself. |
612 | might chose the wrong one unless you load the correct one yourself. |
239 | |
613 | |
240 | You can chose to use a rather inefficient pure-perl implementation by |
614 | You can chose to use a rather inefficient pure-perl implementation by |
241 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
615 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
242 | generally better. |
616 | behaviour everywhere, but letting AnyEvent chose is generally better. |
|
|
617 | |
|
|
618 | =head1 OTHER MODULES |
|
|
619 | |
|
|
620 | The following is a non-exhaustive list of additional modules that use |
|
|
621 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
622 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
623 | available via CPAN. |
|
|
624 | |
|
|
625 | =over 4 |
|
|
626 | |
|
|
627 | =item L<AnyEvent::Util> |
|
|
628 | |
|
|
629 | Contains various utility functions that replace often-used but blocking |
|
|
630 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
631 | |
|
|
632 | =item L<AnyEvent::Handle> |
|
|
633 | |
|
|
634 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
635 | |
|
|
636 | =item L<AnyEvent::Socket> |
|
|
637 | |
|
|
638 | Provides various utility functions for (internet protocol) sockets, |
|
|
639 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
640 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
641 | |
|
|
642 | =item L<AnyEvent::HTTPD> |
|
|
643 | |
|
|
644 | Provides a simple web application server framework. |
|
|
645 | |
|
|
646 | =item L<AnyEvent::DNS> |
|
|
647 | |
|
|
648 | Provides rich asynchronous DNS resolver capabilities. |
|
|
649 | |
|
|
650 | =item L<AnyEvent::FastPing> |
|
|
651 | |
|
|
652 | The fastest ping in the west. |
|
|
653 | |
|
|
654 | =item L<Net::IRC3> |
|
|
655 | |
|
|
656 | AnyEvent based IRC client module family. |
|
|
657 | |
|
|
658 | =item L<Net::XMPP2> |
|
|
659 | |
|
|
660 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
661 | |
|
|
662 | =item L<Net::FCP> |
|
|
663 | |
|
|
664 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
665 | of AnyEvent. |
|
|
666 | |
|
|
667 | =item L<Event::ExecFlow> |
|
|
668 | |
|
|
669 | High level API for event-based execution flow control. |
|
|
670 | |
|
|
671 | =item L<Coro> |
|
|
672 | |
|
|
673 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
674 | |
|
|
675 | =item L<AnyEvent::AIO>, L<IO::AIO> |
|
|
676 | |
|
|
677 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
678 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
679 | together. |
|
|
680 | |
|
|
681 | =item L<AnyEvent::BDB>, L<BDB> |
|
|
682 | |
|
|
683 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses |
|
|
684 | IO::AIO and AnyEvent together. |
|
|
685 | |
|
|
686 | =item L<IO::Lambda> |
|
|
687 | |
|
|
688 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
689 | |
|
|
690 | =back |
243 | |
691 | |
244 | =cut |
692 | =cut |
245 | |
693 | |
246 | package AnyEvent; |
694 | package AnyEvent; |
247 | |
695 | |
248 | no warnings; |
696 | no warnings; |
249 | use strict; |
697 | use strict; |
|
|
698 | |
250 | use Carp; |
699 | use Carp; |
251 | |
700 | |
252 | our $VERSION = '2.52'; |
701 | our $VERSION = '3.6'; |
253 | our $MODEL; |
702 | our $MODEL; |
254 | |
703 | |
255 | our $AUTOLOAD; |
704 | our $AUTOLOAD; |
256 | our @ISA; |
705 | our @ISA; |
257 | |
706 | |
258 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
707 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
259 | |
708 | |
260 | our @REGISTRY; |
709 | our @REGISTRY; |
261 | |
710 | |
|
|
711 | our %PROTOCOL; # (ipv4|ipv6) => (1|2) |
|
|
712 | |
|
|
713 | { |
|
|
714 | my $idx; |
|
|
715 | $PROTOCOL{$_} = ++$idx |
|
|
716 | for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
717 | } |
|
|
718 | |
262 | my @models = ( |
719 | my @models = ( |
263 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
720 | [EV:: => AnyEvent::Impl::EV::], |
264 | [Event:: => AnyEvent::Impl::Event::], |
721 | [Event:: => AnyEvent::Impl::Event::], |
|
|
722 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
723 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
724 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
725 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
726 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
265 | [Glib:: => AnyEvent::Impl::Glib::], |
727 | [Glib:: => AnyEvent::Impl::Glib::], |
266 | [Tk:: => AnyEvent::Impl::Tk::], |
728 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
267 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
729 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
730 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
268 | ); |
731 | ); |
269 | |
732 | |
270 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
733 | our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); |
|
|
734 | |
|
|
735 | our @post_detect; |
|
|
736 | |
|
|
737 | sub post_detect(&) { |
|
|
738 | my ($cb) = @_; |
|
|
739 | |
|
|
740 | if ($MODEL) { |
|
|
741 | $cb->(); |
|
|
742 | |
|
|
743 | 1 |
|
|
744 | } else { |
|
|
745 | push @post_detect, $cb; |
|
|
746 | |
|
|
747 | defined wantarray |
|
|
748 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
749 | : () |
|
|
750 | } |
|
|
751 | } |
|
|
752 | |
|
|
753 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
754 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
755 | } |
271 | |
756 | |
272 | sub detect() { |
757 | sub detect() { |
273 | unless ($MODEL) { |
758 | unless ($MODEL) { |
274 | no strict 'refs'; |
759 | no strict 'refs'; |
275 | |
760 | |
|
|
761 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
762 | my $model = "AnyEvent::Impl::$1"; |
|
|
763 | if (eval "require $model") { |
|
|
764 | $MODEL = $model; |
|
|
765 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
766 | } else { |
|
|
767 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
768 | } |
|
|
769 | } |
|
|
770 | |
276 | # check for already loaded models |
771 | # check for already loaded models |
|
|
772 | unless ($MODEL) { |
277 | for (@REGISTRY, @models) { |
773 | for (@REGISTRY, @models) { |
278 | my ($package, $model) = @$_; |
774 | my ($package, $model) = @$_; |
279 | if (${"$package\::VERSION"} > 0) { |
775 | if (${"$package\::VERSION"} > 0) { |
280 | if (eval "require $model") { |
776 | if (eval "require $model") { |
281 | $MODEL = $model; |
777 | $MODEL = $model; |
282 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
778 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
283 | last; |
779 | last; |
|
|
780 | } |
284 | } |
781 | } |
285 | } |
782 | } |
286 | } |
|
|
287 | |
783 | |
288 | unless ($MODEL) { |
784 | unless ($MODEL) { |
289 | # try to load a model |
785 | # try to load a model |
290 | |
786 | |
291 | for (@REGISTRY, @models) { |
787 | for (@REGISTRY, @models) { |
292 | my ($package, $model) = @$_; |
788 | my ($package, $model) = @$_; |
293 | if (eval "require $package" |
789 | if (eval "require $package" |
294 | and ${"$package\::VERSION"} > 0 |
790 | and ${"$package\::VERSION"} > 0 |
295 | and eval "require $model") { |
791 | and eval "require $model") { |
296 | $MODEL = $model; |
792 | $MODEL = $model; |
297 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
793 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
298 | last; |
794 | last; |
|
|
795 | } |
299 | } |
796 | } |
|
|
797 | |
|
|
798 | $MODEL |
|
|
799 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
300 | } |
800 | } |
301 | |
|
|
302 | $MODEL |
|
|
303 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk."; |
|
|
304 | } |
801 | } |
305 | |
802 | |
306 | unshift @ISA, $MODEL; |
803 | unshift @ISA, $MODEL; |
307 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
804 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
|
|
805 | |
|
|
806 | (shift @post_detect)->() while @post_detect; |
308 | } |
807 | } |
309 | |
808 | |
310 | $MODEL |
809 | $MODEL |
311 | } |
810 | } |
312 | |
811 | |
… | |
… | |
322 | $class->$func (@_); |
821 | $class->$func (@_); |
323 | } |
822 | } |
324 | |
823 | |
325 | package AnyEvent::Base; |
824 | package AnyEvent::Base; |
326 | |
825 | |
327 | # default implementation for ->condvar, ->wait, ->broadcast |
826 | # default implementation for ->condvar |
328 | |
827 | |
329 | sub condvar { |
828 | sub condvar { |
330 | bless \my $flag, "AnyEvent::Base::CondVar" |
829 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
331 | } |
|
|
332 | |
|
|
333 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
334 | ${$_[0]}++; |
|
|
335 | } |
|
|
336 | |
|
|
337 | sub AnyEvent::Base::CondVar::wait { |
|
|
338 | AnyEvent->one_event while !${$_[0]}; |
|
|
339 | } |
830 | } |
340 | |
831 | |
341 | # default implementation for ->signal |
832 | # default implementation for ->signal |
342 | |
833 | |
343 | our %SIG_CB; |
834 | our %SIG_CB; |
… | |
… | |
366 | |
857 | |
367 | # default implementation for ->child |
858 | # default implementation for ->child |
368 | |
859 | |
369 | our %PID_CB; |
860 | our %PID_CB; |
370 | our $CHLD_W; |
861 | our $CHLD_W; |
|
|
862 | our $CHLD_DELAY_W; |
371 | our $PID_IDLE; |
863 | our $PID_IDLE; |
372 | our $WNOHANG; |
864 | our $WNOHANG; |
373 | |
865 | |
374 | sub _child_wait { |
866 | sub _child_wait { |
375 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
867 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
376 | $_->() for values %{ (delete $PID_CB{$pid}) || {} }; |
868 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
|
|
869 | (values %{ $PID_CB{0} || {} }); |
377 | } |
870 | } |
378 | |
871 | |
379 | undef $PID_IDLE; |
872 | undef $PID_IDLE; |
|
|
873 | } |
|
|
874 | |
|
|
875 | sub _sigchld { |
|
|
876 | # make sure we deliver these changes "synchronous" with the event loop. |
|
|
877 | $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
|
|
878 | undef $CHLD_DELAY_W; |
|
|
879 | &_child_wait; |
|
|
880 | }); |
380 | } |
881 | } |
381 | |
882 | |
382 | sub child { |
883 | sub child { |
383 | my (undef, %arg) = @_; |
884 | my (undef, %arg) = @_; |
384 | |
885 | |
385 | my $pid = uc $arg{pid} |
886 | defined (my $pid = $arg{pid} + 0) |
386 | or Carp::croak "required option 'pid' is missing"; |
887 | or Carp::croak "required option 'pid' is missing"; |
387 | |
888 | |
388 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
889 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
389 | |
890 | |
390 | unless ($WNOHANG) { |
891 | unless ($WNOHANG) { |
391 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
892 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
392 | } |
893 | } |
393 | |
894 | |
394 | unless ($CHLD_W) { |
895 | unless ($CHLD_W) { |
395 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait); |
896 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
396 | # child could be a zombie already |
897 | # child could be a zombie already, so make at least one round |
397 | $PID_IDLE ||= AnyEvent->timer (after => 0, cb => \&_child_wait); |
898 | &_sigchld; |
398 | } |
899 | } |
399 | |
900 | |
400 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
901 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
401 | } |
902 | } |
402 | |
903 | |
… | |
… | |
407 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
908 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
408 | |
909 | |
409 | undef $CHLD_W unless keys %PID_CB; |
910 | undef $CHLD_W unless keys %PID_CB; |
410 | } |
911 | } |
411 | |
912 | |
|
|
913 | package AnyEvent::CondVar; |
|
|
914 | |
|
|
915 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
916 | |
|
|
917 | package AnyEvent::CondVar::Base; |
|
|
918 | |
|
|
919 | sub _send { |
|
|
920 | # nop |
|
|
921 | } |
|
|
922 | |
|
|
923 | sub send { |
|
|
924 | my $cv = shift; |
|
|
925 | $cv->{_ae_sent} = [@_]; |
|
|
926 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
927 | $cv->_send; |
|
|
928 | } |
|
|
929 | |
|
|
930 | sub croak { |
|
|
931 | $_[0]{_ae_croak} = $_[1]; |
|
|
932 | $_[0]->send; |
|
|
933 | } |
|
|
934 | |
|
|
935 | sub ready { |
|
|
936 | $_[0]{_ae_sent} |
|
|
937 | } |
|
|
938 | |
|
|
939 | sub _wait { |
|
|
940 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
941 | } |
|
|
942 | |
|
|
943 | sub recv { |
|
|
944 | $_[0]->_wait; |
|
|
945 | |
|
|
946 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
947 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
948 | } |
|
|
949 | |
|
|
950 | sub cb { |
|
|
951 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
952 | $_[0]{_ae_cb} |
|
|
953 | } |
|
|
954 | |
|
|
955 | sub begin { |
|
|
956 | ++$_[0]{_ae_counter}; |
|
|
957 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
958 | } |
|
|
959 | |
|
|
960 | sub end { |
|
|
961 | return if --$_[0]{_ae_counter}; |
|
|
962 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
963 | } |
|
|
964 | |
|
|
965 | # undocumented/compatibility with pre-3.4 |
|
|
966 | *broadcast = \&send; |
|
|
967 | *wait = \&_wait; |
|
|
968 | |
412 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
969 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
970 | |
|
|
971 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
972 | a module. This section is only of use to event loop authors who want to |
|
|
973 | provide AnyEvent compatibility. |
413 | |
974 | |
414 | If you need to support another event library which isn't directly |
975 | If you need to support another event library which isn't directly |
415 | supported by AnyEvent, you can supply your own interface to it by |
976 | supported by AnyEvent, you can supply your own interface to it by |
416 | pushing, before the first watcher gets created, the package name of |
977 | pushing, before the first watcher gets created, the package name of |
417 | the event module and the package name of the interface to use onto |
978 | the event module and the package name of the interface to use onto |
418 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
979 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
419 | AnyEvent. |
980 | AnyEvent, so it is reasonably cheap. |
420 | |
981 | |
421 | Example: |
982 | Example: |
422 | |
983 | |
423 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
984 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
424 | |
985 | |
425 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
986 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
426 | package/class when it finds the C<urxvt> package/module is loaded. When |
987 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
988 | |
427 | AnyEvent is loaded and asked to find a suitable event model, it will |
989 | When AnyEvent is loaded and asked to find a suitable event model, it |
428 | first check for the presence of urxvt. |
990 | will first check for the presence of urxvt by trying to C<use> the |
|
|
991 | C<urxvt::anyevent> module. |
429 | |
992 | |
430 | The class should provide implementations for all watcher types (see |
993 | The class should provide implementations for all watcher types. See |
431 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
994 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
432 | (Source code) and so on for actual examples, use C<perldoc -m |
995 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
433 | AnyEvent::Impl::Glib> to see the sources). |
996 | see the sources. |
434 | |
997 | |
|
|
998 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
999 | provide suitable (hopefully) replacements. |
|
|
1000 | |
435 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
1001 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
436 | uses the above line as-is. An interface isn't included in AnyEvent |
1002 | terminal emulator uses the above line as-is. An interface isn't included |
437 | because it doesn't make sense outside the embedded interpreter inside |
1003 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
438 | I<rxvt-unicode>, and it is updated and maintained as part of the |
1004 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
439 | I<rxvt-unicode> distribution. |
1005 | I<rxvt-unicode> distribution. |
440 | |
1006 | |
441 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
1007 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
442 | condition variables: code blocking while waiting for a condition will |
1008 | condition variables: code blocking while waiting for a condition will |
443 | C<die>. This still works with most modules/usages, and blocking calls must |
1009 | C<die>. This still works with most modules/usages, and blocking calls must |
444 | not be in an interactive appliation, so it makes sense. |
1010 | not be done in an interactive application, so it makes sense. |
445 | |
1011 | |
446 | =head1 ENVIRONMENT VARIABLES |
1012 | =head1 ENVIRONMENT VARIABLES |
447 | |
1013 | |
448 | The following environment variables are used by this module: |
1014 | The following environment variables are used by this module: |
449 | |
1015 | |
450 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
1016 | =over 4 |
451 | model gets used. |
|
|
452 | |
1017 | |
|
|
1018 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1019 | |
|
|
1020 | By default, AnyEvent will be completely silent except in fatal |
|
|
1021 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1022 | talkative. |
|
|
1023 | |
|
|
1024 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1025 | conditions, such as not being able to load the event model specified by |
|
|
1026 | C<PERL_ANYEVENT_MODEL>. |
|
|
1027 | |
|
|
1028 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1029 | model it chooses. |
|
|
1030 | |
|
|
1031 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1032 | |
|
|
1033 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1034 | auto detection and -probing kicks in. It must be a string consisting |
|
|
1035 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1036 | and the resulting module name is loaded and if the load was successful, |
|
|
1037 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1038 | auto detection and -probing. |
|
|
1039 | |
|
|
1040 | This functionality might change in future versions. |
|
|
1041 | |
|
|
1042 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1043 | could start your program like this: |
|
|
1044 | |
|
|
1045 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1046 | |
|
|
1047 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1048 | |
|
|
1049 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1050 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1051 | of auto probing). |
|
|
1052 | |
|
|
1053 | Must be set to a comma-separated list of protocols or address families, |
|
|
1054 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1055 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1056 | list. |
|
|
1057 | |
|
|
1058 | This variable can effectively be used for denial-of-service attacks |
|
|
1059 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1060 | small, as the program has to handle connection errors already- |
|
|
1061 | |
|
|
1062 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1063 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1064 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1065 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1066 | IPv6, but prefer IPv6 over IPv4. |
|
|
1067 | |
|
|
1068 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1069 | |
|
|
1070 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1071 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1072 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1073 | default. |
|
|
1074 | |
|
|
1075 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1076 | EDNS0 in its DNS requests. |
|
|
1077 | |
|
|
1078 | =back |
|
|
1079 | |
453 | =head1 EXAMPLE |
1080 | =head1 EXAMPLE PROGRAM |
454 | |
1081 | |
455 | The following program uses an io watcher to read data from stdin, a timer |
1082 | The following program uses an I/O watcher to read data from STDIN, a timer |
456 | to display a message once per second, and a condvar to exit the program |
1083 | to display a message once per second, and a condition variable to quit the |
457 | when the user enters quit: |
1084 | program when the user enters quit: |
458 | |
1085 | |
459 | use AnyEvent; |
1086 | use AnyEvent; |
460 | |
1087 | |
461 | my $cv = AnyEvent->condvar; |
1088 | my $cv = AnyEvent->condvar; |
462 | |
1089 | |
463 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
1090 | my $io_watcher = AnyEvent->io ( |
|
|
1091 | fh => \*STDIN, |
|
|
1092 | poll => 'r', |
|
|
1093 | cb => sub { |
464 | warn "io event <$_[0]>\n"; # will always output <r> |
1094 | warn "io event <$_[0]>\n"; # will always output <r> |
465 | chomp (my $input = <STDIN>); # read a line |
1095 | chomp (my $input = <STDIN>); # read a line |
466 | warn "read: $input\n"; # output what has been read |
1096 | warn "read: $input\n"; # output what has been read |
467 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1097 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
|
|
1098 | }, |
468 | }); |
1099 | ); |
469 | |
1100 | |
470 | my $time_watcher; # can only be used once |
1101 | my $time_watcher; # can only be used once |
471 | |
1102 | |
472 | sub new_timer { |
1103 | sub new_timer { |
473 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1104 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
476 | }); |
1107 | }); |
477 | } |
1108 | } |
478 | |
1109 | |
479 | new_timer; # create first timer |
1110 | new_timer; # create first timer |
480 | |
1111 | |
481 | $cv->wait; # wait until user enters /^q/i |
1112 | $cv->recv; # wait until user enters /^q/i |
482 | |
1113 | |
483 | =head1 REAL-WORLD EXAMPLE |
1114 | =head1 REAL-WORLD EXAMPLE |
484 | |
1115 | |
485 | Consider the L<Net::FCP> module. It features (among others) the following |
1116 | Consider the L<Net::FCP> module. It features (among others) the following |
486 | API calls, which are to freenet what HTTP GET requests are to http: |
1117 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
536 | syswrite $txn->{fh}, $txn->{request} |
1167 | syswrite $txn->{fh}, $txn->{request} |
537 | or die "connection or write error"; |
1168 | or die "connection or write error"; |
538 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1169 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
539 | |
1170 | |
540 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1171 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
541 | result and signals any possible waiters that the request ahs finished: |
1172 | result and signals any possible waiters that the request has finished: |
542 | |
1173 | |
543 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1174 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
544 | |
1175 | |
545 | if (end-of-file or data complete) { |
1176 | if (end-of-file or data complete) { |
546 | $txn->{result} = $txn->{buf}; |
1177 | $txn->{result} = $txn->{buf}; |
547 | $txn->{finished}->broadcast; |
1178 | $txn->{finished}->send; |
548 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1179 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
549 | } |
1180 | } |
550 | |
1181 | |
551 | The C<result> method, finally, just waits for the finished signal (if the |
1182 | The C<result> method, finally, just waits for the finished signal (if the |
552 | request was already finished, it doesn't wait, of course, and returns the |
1183 | request was already finished, it doesn't wait, of course, and returns the |
553 | data: |
1184 | data: |
554 | |
1185 | |
555 | $txn->{finished}->wait; |
1186 | $txn->{finished}->recv; |
556 | return $txn->{result}; |
1187 | return $txn->{result}; |
557 | |
1188 | |
558 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1189 | The actual code goes further and collects all errors (C<die>s, exceptions) |
559 | that occured during request processing. The C<result> method detects |
1190 | that occurred during request processing. The C<result> method detects |
560 | wether an exception as thrown (it is stored inside the $txn object) |
1191 | whether an exception as thrown (it is stored inside the $txn object) |
561 | and just throws the exception, which means connection errors and other |
1192 | and just throws the exception, which means connection errors and other |
562 | problems get reported tot he code that tries to use the result, not in a |
1193 | problems get reported tot he code that tries to use the result, not in a |
563 | random callback. |
1194 | random callback. |
564 | |
1195 | |
565 | All of this enables the following usage styles: |
1196 | All of this enables the following usage styles: |
566 | |
1197 | |
567 | 1. Blocking: |
1198 | 1. Blocking: |
568 | |
1199 | |
569 | my $data = $fcp->client_get ($url); |
1200 | my $data = $fcp->client_get ($url); |
570 | |
1201 | |
571 | 2. Blocking, but parallelizing: |
1202 | 2. Blocking, but running in parallel: |
572 | |
1203 | |
573 | my @datas = map $_->result, |
1204 | my @datas = map $_->result, |
574 | map $fcp->txn_client_get ($_), |
1205 | map $fcp->txn_client_get ($_), |
575 | @urls; |
1206 | @urls; |
576 | |
1207 | |
577 | Both blocking examples work without the module user having to know |
1208 | Both blocking examples work without the module user having to know |
578 | anything about events. |
1209 | anything about events. |
579 | |
1210 | |
580 | 3a. Event-based in a main program, using any support Event module: |
1211 | 3a. Event-based in a main program, using any supported event module: |
581 | |
1212 | |
582 | use Event; |
1213 | use EV; |
583 | |
1214 | |
584 | $fcp->txn_client_get ($url)->cb (sub { |
1215 | $fcp->txn_client_get ($url)->cb (sub { |
585 | my $txn = shift; |
1216 | my $txn = shift; |
586 | my $data = $txn->result; |
1217 | my $data = $txn->result; |
587 | ... |
1218 | ... |
588 | }); |
1219 | }); |
589 | |
1220 | |
590 | Event::loop; |
1221 | EV::loop; |
591 | |
1222 | |
592 | 3b. The module user could use AnyEvent, too: |
1223 | 3b. The module user could use AnyEvent, too: |
593 | |
1224 | |
594 | use AnyEvent; |
1225 | use AnyEvent; |
595 | |
1226 | |
596 | my $quit = AnyEvent->condvar; |
1227 | my $quit = AnyEvent->condvar; |
597 | |
1228 | |
598 | $fcp->txn_client_get ($url)->cb (sub { |
1229 | $fcp->txn_client_get ($url)->cb (sub { |
599 | ... |
1230 | ... |
600 | $quit->broadcast; |
1231 | $quit->send; |
601 | }); |
1232 | }); |
602 | |
1233 | |
603 | $quit->wait; |
1234 | $quit->recv; |
|
|
1235 | |
|
|
1236 | |
|
|
1237 | =head1 BENCHMARKS |
|
|
1238 | |
|
|
1239 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1240 | over the event loops themselves and to give you an impression of the speed |
|
|
1241 | of various event loops I prepared some benchmarks. |
|
|
1242 | |
|
|
1243 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1244 | |
|
|
1245 | Here is a benchmark of various supported event models used natively and |
|
|
1246 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1247 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1248 | which it is), lets them fire exactly once and destroys them again. |
|
|
1249 | |
|
|
1250 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1251 | distribution. |
|
|
1252 | |
|
|
1253 | =head3 Explanation of the columns |
|
|
1254 | |
|
|
1255 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1256 | different event models feature vastly different performances, each event |
|
|
1257 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1258 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1259 | would probably take thousands of years if asked to process the same number |
|
|
1260 | of watchers as EV in this benchmark. |
|
|
1261 | |
|
|
1262 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1263 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1264 | and Perl-based overheads. |
|
|
1265 | |
|
|
1266 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1267 | takes to create a single watcher. The callback is a closure shared between |
|
|
1268 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1269 | and memory usage is not included in the figures. |
|
|
1270 | |
|
|
1271 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1272 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1273 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1274 | signal the end of this phase. |
|
|
1275 | |
|
|
1276 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1277 | watcher. |
|
|
1278 | |
|
|
1279 | =head3 Results |
|
|
1280 | |
|
|
1281 | name watchers bytes create invoke destroy comment |
|
|
1282 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1283 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1284 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1285 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1286 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1287 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1288 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1289 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1290 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1291 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1292 | |
|
|
1293 | =head3 Discussion |
|
|
1294 | |
|
|
1295 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1296 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1297 | can never compete with an event loop that uses epoll when the number of |
|
|
1298 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1299 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1300 | boost. |
|
|
1301 | |
|
|
1302 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1303 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1304 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1305 | higher number of watchers at a disadvantage. |
|
|
1306 | |
|
|
1307 | To put the range of results into perspective, consider that on the |
|
|
1308 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1309 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1310 | cycles with POE. |
|
|
1311 | |
|
|
1312 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1313 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1314 | far less memory than any other event loop and is still faster than Event |
|
|
1315 | natively. |
|
|
1316 | |
|
|
1317 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1318 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1319 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1320 | adds very little overhead in itself. Like any select-based backend its |
|
|
1321 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1322 | them active), of course, but this was not subject of this benchmark. |
|
|
1323 | |
|
|
1324 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1325 | cost, but overall scores in on the third place. |
|
|
1326 | |
|
|
1327 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1328 | faster callback invocation and overall ends up in the same class as |
|
|
1329 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1330 | watchers increases the processing time by more than a factor of four, |
|
|
1331 | making it completely unusable when using larger numbers of watchers |
|
|
1332 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1333 | inefficiencies of C<poll> do not account for this). |
|
|
1334 | |
|
|
1335 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1336 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1337 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1338 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1339 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1340 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1341 | above). |
|
|
1342 | |
|
|
1343 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1344 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1345 | be tested because it wasn't working) shows abysmal performance and |
|
|
1346 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1347 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1348 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1349 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1350 | implementation. |
|
|
1351 | |
|
|
1352 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1353 | for the performance issues, though, as session creation overhead is |
|
|
1354 | small compared to execution of the state machine, which is coded pretty |
|
|
1355 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1356 | using multiple sessions is not a good approach, especially regarding |
|
|
1357 | memory usage, even the author of POE could not come up with a faster |
|
|
1358 | design). |
|
|
1359 | |
|
|
1360 | =head3 Summary |
|
|
1361 | |
|
|
1362 | =over 4 |
|
|
1363 | |
|
|
1364 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1365 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1366 | performance with or without AnyEvent. |
|
|
1367 | |
|
|
1368 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1369 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1370 | adds AnyEvent significant overhead. |
|
|
1371 | |
|
|
1372 | =item * You should avoid POE like the plague if you want performance or |
|
|
1373 | reasonable memory usage. |
|
|
1374 | |
|
|
1375 | =back |
|
|
1376 | |
|
|
1377 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1378 | |
|
|
1379 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1380 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1381 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1382 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1383 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1384 | |
|
|
1385 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1386 | are active at any one point (so there is a constant number of active |
|
|
1387 | fds for each loop iteration, but which fds these are is random). The |
|
|
1388 | timeout is reset each time something is read because that reflects how |
|
|
1389 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1390 | |
|
|
1391 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1392 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1393 | connections, most of which are idle at any one point in time. |
|
|
1394 | |
|
|
1395 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1396 | distribution. |
|
|
1397 | |
|
|
1398 | =head3 Explanation of the columns |
|
|
1399 | |
|
|
1400 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1401 | each server has a read and write socket end). |
|
|
1402 | |
|
|
1403 | I<create> is the time it takes to create a socket pair (which is |
|
|
1404 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1405 | |
|
|
1406 | I<request>, the most important value, is the time it takes to handle a |
|
|
1407 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1408 | it to another server. This includes deleting the old timeout and creating |
|
|
1409 | a new one that moves the timeout into the future. |
|
|
1410 | |
|
|
1411 | =head3 Results |
|
|
1412 | |
|
|
1413 | name sockets create request |
|
|
1414 | EV 20000 69.01 11.16 |
|
|
1415 | Perl 20000 73.32 35.87 |
|
|
1416 | Event 20000 212.62 257.32 |
|
|
1417 | Glib 20000 651.16 1896.30 |
|
|
1418 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1419 | |
|
|
1420 | =head3 Discussion |
|
|
1421 | |
|
|
1422 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1423 | particular event loop. |
|
|
1424 | |
|
|
1425 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1426 | is relatively high, though. |
|
|
1427 | |
|
|
1428 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1429 | loops Event and Glib. |
|
|
1430 | |
|
|
1431 | Event suffers from high setup time as well (look at its code and you will |
|
|
1432 | understand why). Callback invocation also has a high overhead compared to |
|
|
1433 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1434 | uses select or poll in basically all documented configurations. |
|
|
1435 | |
|
|
1436 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1437 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1438 | |
|
|
1439 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1440 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1441 | it uses a C-based event loop in this case. |
|
|
1442 | |
|
|
1443 | =head3 Summary |
|
|
1444 | |
|
|
1445 | =over 4 |
|
|
1446 | |
|
|
1447 | =item * The pure perl implementation performs extremely well. |
|
|
1448 | |
|
|
1449 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1450 | |
|
|
1451 | =back |
|
|
1452 | |
|
|
1453 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1454 | |
|
|
1455 | While event loops should scale (and select-based ones do not...) even to |
|
|
1456 | large servers, most programs we (or I :) actually write have only a few |
|
|
1457 | I/O watchers. |
|
|
1458 | |
|
|
1459 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1460 | case, but it uses only eight "servers", of which three are active at any |
|
|
1461 | one time. This should reflect performance for a small server relatively |
|
|
1462 | well. |
|
|
1463 | |
|
|
1464 | The columns are identical to the previous table. |
|
|
1465 | |
|
|
1466 | =head3 Results |
|
|
1467 | |
|
|
1468 | name sockets create request |
|
|
1469 | EV 16 20.00 6.54 |
|
|
1470 | Perl 16 25.75 12.62 |
|
|
1471 | Event 16 81.27 35.86 |
|
|
1472 | Glib 16 32.63 15.48 |
|
|
1473 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1474 | |
|
|
1475 | =head3 Discussion |
|
|
1476 | |
|
|
1477 | The benchmark tries to test the performance of a typical small |
|
|
1478 | server. While knowing how various event loops perform is interesting, keep |
|
|
1479 | in mind that their overhead in this case is usually not as important, due |
|
|
1480 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1481 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1482 | them). |
|
|
1483 | |
|
|
1484 | EV is again fastest. |
|
|
1485 | |
|
|
1486 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1487 | loops Event and Glib, although the difference is too small to really |
|
|
1488 | matter. |
|
|
1489 | |
|
|
1490 | POE also performs much better in this case, but is is still far behind the |
|
|
1491 | others. |
|
|
1492 | |
|
|
1493 | =head3 Summary |
|
|
1494 | |
|
|
1495 | =over 4 |
|
|
1496 | |
|
|
1497 | =item * C-based event loops perform very well with small number of |
|
|
1498 | watchers, as the management overhead dominates. |
|
|
1499 | |
|
|
1500 | =back |
|
|
1501 | |
|
|
1502 | |
|
|
1503 | =head1 FORK |
|
|
1504 | |
|
|
1505 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1506 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1507 | calls. Only L<EV> is fully fork-aware. |
|
|
1508 | |
|
|
1509 | If you have to fork, you must either do so I<before> creating your first |
|
|
1510 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1511 | |
|
|
1512 | |
|
|
1513 | =head1 SECURITY CONSIDERATIONS |
|
|
1514 | |
|
|
1515 | AnyEvent can be forced to load any event model via |
|
|
1516 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1517 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1518 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1519 | will not be active when the program uses a different event model than |
|
|
1520 | specified in the variable. |
|
|
1521 | |
|
|
1522 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1523 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1524 | |
|
|
1525 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1526 | |
|
|
1527 | use AnyEvent; |
|
|
1528 | |
|
|
1529 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1530 | be used to probe what backend is used and gain other information (which is |
|
|
1531 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
|
|
1532 | |
604 | |
1533 | |
605 | =head1 SEE ALSO |
1534 | =head1 SEE ALSO |
606 | |
1535 | |
607 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
1536 | Utility functions: L<AnyEvent::Util>. |
608 | |
1537 | |
609 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
1538 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
|
|
1539 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
610 | |
1540 | |
611 | Nontrivial usage example: L<Net::FCP>. |
1541 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
|
|
1542 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
1543 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
1544 | L<AnyEvent::Impl::POE>. |
612 | |
1545 | |
613 | =head1 |
1546 | Non-blocking file handles, sockets, TCP clients and |
|
|
1547 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1548 | |
|
|
1549 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1550 | |
|
|
1551 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1552 | |
|
|
1553 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
|
|
1554 | |
|
|
1555 | |
|
|
1556 | =head1 AUTHOR |
|
|
1557 | |
|
|
1558 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1559 | http://home.schmorp.de/ |
614 | |
1560 | |
615 | =cut |
1561 | =cut |
616 | |
1562 | |
617 | 1 |
1563 | 1 |
618 | |
1564 | |