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, Coro::EV, Coro::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 |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
21 | $w->broadcast; # wake up current and all future wait's |
21 | $w->broadcast; # wake up current and all future wait's |
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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 enourmous 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<Coro::EV>, L<Coro::Event>, 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 | |
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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 filehandle 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> the 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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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 occurances 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 guarenteed 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 | AnyEvent::detect; # force event module to be initialised |
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285 | |
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286 | my $pid = fork or exit 5; |
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287 | |
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288 | my $w = AnyEvent->child ( |
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289 | pid => $pid, |
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290 | cb => sub { |
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291 | my ($pid, $status) = @_; |
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292 | warn "pid $pid exited with status $status"; |
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293 | $done->broadcast; |
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294 | }, |
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295 | ); |
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296 | |
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297 | # do something else, then wait for process exit |
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298 | $done->wait; |
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299 | |
116 | =head2 CONDITION WATCHERS |
300 | =head2 CONDITION VARIABLES |
117 | |
301 | |
118 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
302 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
119 | method without any arguments. |
303 | method without any arguments. |
120 | |
304 | |
121 | A condition watcher watches for a condition - precisely that the C<< |
305 | A condition variable waits for a condition - precisely that the C<< |
122 | ->broadcast >> method has been called. |
306 | ->broadcast >> method has been called. |
123 | |
307 | |
124 | The watcher has only two methods: |
308 | They are very useful to signal that a condition has been fulfilled, for |
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309 | example, if you write a module that does asynchronous http requests, |
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310 | then a condition variable would be the ideal candidate to signal the |
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311 | availability of results. |
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312 | |
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313 | You can also use condition variables to block your main program until |
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314 | an event occurs - for example, you could C<< ->wait >> in your main |
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315 | program until the user clicks the Quit button in your app, which would C<< |
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316 | ->broadcast >> the "quit" event. |
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317 | |
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318 | Note that condition variables recurse into the event loop - if you have |
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319 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
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320 | lose. Therefore, condition variables are good to export to your caller, but |
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321 | you should avoid making a blocking wait yourself, at least in callbacks, |
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322 | as this asks for trouble. |
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323 | |
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324 | This object has two methods: |
125 | |
325 | |
126 | =over 4 |
326 | =over 4 |
127 | |
327 | |
128 | =item $cv->wait |
328 | =item $cv->wait |
129 | |
329 | |
130 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
330 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
131 | called on c<$cv>, while servicing other watchers normally. |
331 | called on c<$cv>, while servicing other watchers normally. |
132 | |
332 | |
133 | Not all event models support a blocking wait - some die in that case, so |
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134 | if you are using this from a module, never require a blocking wait, but |
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135 | let the caller decide wether the call will block or not (for example, |
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136 | by coupling condition variables with some kind of request results and |
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137 | supporting callbacks so the caller knows that getting the result will not |
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138 | block, while still suppporting blockign waits if the caller so desires). |
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139 | |
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140 | You can only wait once on a condition - additional calls will return |
333 | You can only wait once on a condition - additional calls will return |
141 | immediately. |
334 | immediately. |
142 | |
335 | |
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336 | Not all event models support a blocking wait - some die in that case |
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337 | (programs might want to do that to stay interactive), so I<if you are |
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338 | using this from a module, never require a blocking wait>, but let the |
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339 | caller decide whether the call will block or not (for example, by coupling |
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340 | condition variables with some kind of request results and supporting |
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341 | callbacks so the caller knows that getting the result will not block, |
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342 | while still suppporting blocking waits if the caller so desires). |
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343 | |
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344 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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345 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
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346 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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347 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
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348 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
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349 | from different coroutines, however). |
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350 | |
143 | =item $cv->broadcast |
351 | =item $cv->broadcast |
144 | |
352 | |
145 | Flag the condition as ready - a running C<< ->wait >> and all further |
353 | Flag the condition as ready - a running C<< ->wait >> and all further |
146 | calls to C<wait> will return after this method has been called. If nobody |
354 | calls to C<wait> will (eventually) return after this method has been |
147 | is waiting the broadcast will be remembered.. |
355 | called. If nobody is waiting the broadcast will be remembered.. |
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356 | |
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357 | =back |
148 | |
358 | |
149 | Example: |
359 | Example: |
150 | |
360 | |
151 | # wait till the result is ready |
361 | # wait till the result is ready |
152 | my $result_ready = AnyEvent->condvar; |
362 | my $result_ready = AnyEvent->condvar; |
153 | |
363 | |
154 | # do something such as adding a timer |
364 | # do something such as adding a timer |
155 | # or socket watcher the calls $result_ready->broadcast |
365 | # or socket watcher the calls $result_ready->broadcast |
156 | # when the "result" is ready. |
366 | # when the "result" is ready. |
|
|
367 | # in this case, we simply use a timer: |
|
|
368 | my $w = AnyEvent->timer ( |
|
|
369 | after => 1, |
|
|
370 | cb => sub { $result_ready->broadcast }, |
|
|
371 | ); |
157 | |
372 | |
|
|
373 | # this "blocks" (while handling events) till the watcher |
|
|
374 | # calls broadcast |
158 | $result_ready->wait; |
375 | $result_ready->wait; |
159 | |
376 | |
160 | =back |
377 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
161 | |
|
|
162 | =head2 SIGNAL WATCHERS |
|
|
163 | |
|
|
164 | You can listen for signals using a signal watcher, C<signal> is the signal |
|
|
165 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
|
|
166 | together into one callback invocation, and callback invocation might or |
|
|
167 | might not be asynchronous. |
|
|
168 | |
|
|
169 | These watchers might use C<%SIG>, so programs overwriting those signals |
|
|
170 | directly will likely not work correctly. |
|
|
171 | |
|
|
172 | Example: exit on SIGINT |
|
|
173 | |
|
|
174 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
175 | |
|
|
176 | =head2 CHILD PROCESS WATCHERS |
|
|
177 | |
|
|
178 | You can also listen for the status of a child process specified by the |
|
|
179 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
|
|
180 | trigger as often as status change for the child are received. This works |
|
|
181 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
|
|
182 | the pid and exit status (as returned by waitpid). |
|
|
183 | |
|
|
184 | Example: wait for pid 1333 |
|
|
185 | |
|
|
186 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
|
|
187 | |
|
|
188 | =head1 GLOBALS |
|
|
189 | |
378 | |
190 | =over 4 |
379 | =over 4 |
191 | |
380 | |
192 | =item $AnyEvent::MODEL |
381 | =item $AnyEvent::MODEL |
193 | |
382 | |
… | |
… | |
198 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
387 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
199 | |
388 | |
200 | The known classes so far are: |
389 | The known classes so far are: |
201 | |
390 | |
202 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
391 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
|
|
392 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
203 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
393 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
204 | AnyEvent::Impl::Coro based on Coro::Event, second best choice. |
|
|
205 | AnyEvent::Impl::Event based on Event, also second best choice :) |
394 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
395 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
206 | AnyEvent::Impl::Glib based on Glib, second-best choice. |
396 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
207 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
397 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
208 | AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
398 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
399 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
400 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
401 | |
|
|
402 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
403 | watching file handles. However, you can use WxWidgets through the |
|
|
404 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
405 | second, which was considered to be too horrible to even consider for |
|
|
406 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
407 | it's adaptor. |
|
|
408 | |
|
|
409 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
410 | autodetecting them. |
209 | |
411 | |
210 | =item AnyEvent::detect |
412 | =item AnyEvent::detect |
211 | |
413 | |
212 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
414 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
213 | necessary. You should only call this function right before you would have |
415 | if necessary. You should only call this function right before you would |
214 | created an AnyEvent watcher anyway, that is, very late at runtime. |
416 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
417 | runtime. |
215 | |
418 | |
216 | =back |
419 | =back |
217 | |
420 | |
218 | =head1 WHAT TO DO IN A MODULE |
421 | =head1 WHAT TO DO IN A MODULE |
219 | |
422 | |
220 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
423 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
221 | freely, but you should not load a specific event module or rely on it. |
424 | freely, but you should not load a specific event module or rely on it. |
222 | |
425 | |
223 | Be careful when you create watchers in the module body - Anyevent will |
426 | Be careful when you create watchers in the module body - AnyEvent will |
224 | decide which event module to use as soon as the first method is called, so |
427 | decide which event module to use as soon as the first method is called, so |
225 | by calling AnyEvent in your module body you force the user of your module |
428 | by calling AnyEvent in your module body you force the user of your module |
226 | to load the event module first. |
429 | to load the event module first. |
227 | |
430 | |
|
|
431 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
|
|
432 | the C<< ->broadcast >> method has been called on it already. This is |
|
|
433 | because it will stall the whole program, and the whole point of using |
|
|
434 | events is to stay interactive. |
|
|
435 | |
|
|
436 | It is fine, however, to call C<< ->wait >> when the user of your module |
|
|
437 | requests it (i.e. if you create a http request object ad have a method |
|
|
438 | called C<results> that returns the results, it should call C<< ->wait >> |
|
|
439 | freely, as the user of your module knows what she is doing. always). |
|
|
440 | |
228 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
441 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
229 | |
442 | |
230 | There will always be a single main program - the only place that should |
443 | There will always be a single main program - the only place that should |
231 | dictate which event model to use. |
444 | dictate which event model to use. |
232 | |
445 | |
233 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
446 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
234 | do anything special and let AnyEvent decide which implementation to chose. |
447 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
448 | decide which implementation to chose if some module relies on it. |
235 | |
449 | |
236 | If the main program relies on a specific event model (for example, in Gtk2 |
450 | If the main program relies on a specific event model. For example, in |
237 | programs you have to rely on either Glib or Glib::Event), you should load |
451 | Gtk2 programs you have to rely on the Glib module. You should load the |
238 | it before loading AnyEvent or any module that uses it, generally, as early |
452 | event module before loading AnyEvent or any module that uses it: generally |
239 | as possible. The reason is that modules might create watchers when they |
453 | speaking, you should load it as early as possible. The reason is that |
240 | are loaded, and AnyEvent will decide on the event model to use as soon as |
454 | modules might create watchers when they are loaded, and AnyEvent will |
241 | it creates watchers, and it might chose the wrong one unless you load the |
455 | decide on the event model to use as soon as it creates watchers, and it |
242 | correct one yourself. |
456 | might chose the wrong one unless you load the correct one yourself. |
243 | |
457 | |
244 | You can chose to use a rather inefficient pure-perl implementation by |
458 | You can chose to use a rather inefficient pure-perl implementation by |
245 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
459 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
246 | generally better. |
460 | behaviour everywhere, but letting AnyEvent chose is generally better. |
|
|
461 | |
|
|
462 | =head1 OTHER MODULES |
|
|
463 | |
|
|
464 | The following is a non-exhaustive list of additional modules that use |
|
|
465 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
466 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
467 | available via CPAN. |
|
|
468 | |
|
|
469 | =over 4 |
|
|
470 | |
|
|
471 | =item L<AnyEvent::Util> |
|
|
472 | |
|
|
473 | Contains various utility functions that replace often-used but blocking |
|
|
474 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
475 | |
|
|
476 | =item L<AnyEvent::Handle> |
|
|
477 | |
|
|
478 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
479 | |
|
|
480 | =item L<AnyEvent::Socket> |
|
|
481 | |
|
|
482 | Provides a means to do non-blocking connects, accepts etc. |
|
|
483 | |
|
|
484 | =item L<AnyEvent::HTTPD> |
|
|
485 | |
|
|
486 | Provides a simple web application server framework. |
|
|
487 | |
|
|
488 | =item L<AnyEvent::DNS> |
|
|
489 | |
|
|
490 | Provides asynchronous DNS resolver capabilities, beyond what |
|
|
491 | L<AnyEvent::Util> offers. |
|
|
492 | |
|
|
493 | =item L<AnyEvent::FastPing> |
|
|
494 | |
|
|
495 | The fastest ping in the west. |
|
|
496 | |
|
|
497 | =item L<Net::IRC3> |
|
|
498 | |
|
|
499 | AnyEvent based IRC client module family. |
|
|
500 | |
|
|
501 | =item L<Net::XMPP2> |
|
|
502 | |
|
|
503 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
504 | |
|
|
505 | =item L<Net::FCP> |
|
|
506 | |
|
|
507 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
508 | of AnyEvent. |
|
|
509 | |
|
|
510 | =item L<Event::ExecFlow> |
|
|
511 | |
|
|
512 | High level API for event-based execution flow control. |
|
|
513 | |
|
|
514 | =item L<Coro> |
|
|
515 | |
|
|
516 | Has special support for AnyEvent. |
|
|
517 | |
|
|
518 | =item L<IO::Lambda> |
|
|
519 | |
|
|
520 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
521 | |
|
|
522 | =item L<IO::AIO> |
|
|
523 | |
|
|
524 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
525 | programmer. Can be trivially made to use AnyEvent. |
|
|
526 | |
|
|
527 | =item L<BDB> |
|
|
528 | |
|
|
529 | Truly asynchronous Berkeley DB access. Can be trivially made to use |
|
|
530 | AnyEvent. |
|
|
531 | |
|
|
532 | =back |
247 | |
533 | |
248 | =cut |
534 | =cut |
249 | |
535 | |
250 | package AnyEvent; |
536 | package AnyEvent; |
251 | |
537 | |
252 | no warnings; |
538 | no warnings; |
253 | use strict; |
539 | use strict; |
254 | |
540 | |
255 | use Carp; |
541 | use Carp; |
256 | |
542 | |
257 | our $VERSION = '2.7'; |
543 | our $VERSION = '3.3'; |
258 | our $MODEL; |
544 | our $MODEL; |
259 | |
545 | |
260 | our $AUTOLOAD; |
546 | our $AUTOLOAD; |
261 | our @ISA; |
547 | our @ISA; |
262 | |
548 | |
… | |
… | |
264 | |
550 | |
265 | our @REGISTRY; |
551 | our @REGISTRY; |
266 | |
552 | |
267 | my @models = ( |
553 | my @models = ( |
268 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
554 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
555 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
269 | [EV:: => AnyEvent::Impl::EV::], |
556 | [EV:: => AnyEvent::Impl::EV::], |
270 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
|
|
271 | [Event:: => AnyEvent::Impl::Event::], |
557 | [Event:: => AnyEvent::Impl::Event::], |
|
|
558 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
559 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
560 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
561 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
562 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
272 | [Glib:: => AnyEvent::Impl::Glib::], |
563 | [Glib:: => AnyEvent::Impl::Glib::], |
273 | [Tk:: => AnyEvent::Impl::Tk::], |
564 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
274 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
565 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
566 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
275 | ); |
567 | ); |
276 | |
568 | |
277 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
569 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
278 | |
570 | |
279 | sub detect() { |
571 | sub detect() { |
280 | unless ($MODEL) { |
572 | unless ($MODEL) { |
281 | no strict 'refs'; |
573 | no strict 'refs'; |
282 | |
574 | |
|
|
575 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
576 | my $model = "AnyEvent::Impl::$1"; |
|
|
577 | if (eval "require $model") { |
|
|
578 | $MODEL = $model; |
|
|
579 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
580 | } else { |
|
|
581 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
582 | } |
|
|
583 | } |
|
|
584 | |
283 | # check for already loaded models |
585 | # check for already loaded models |
|
|
586 | unless ($MODEL) { |
284 | for (@REGISTRY, @models) { |
587 | for (@REGISTRY, @models) { |
285 | my ($package, $model) = @$_; |
588 | my ($package, $model) = @$_; |
286 | if (${"$package\::VERSION"} > 0) { |
589 | if (${"$package\::VERSION"} > 0) { |
287 | if (eval "require $model") { |
590 | if (eval "require $model") { |
288 | $MODEL = $model; |
591 | $MODEL = $model; |
289 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
592 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
290 | last; |
593 | last; |
|
|
594 | } |
291 | } |
595 | } |
292 | } |
596 | } |
293 | } |
|
|
294 | |
597 | |
295 | unless ($MODEL) { |
598 | unless ($MODEL) { |
296 | # try to load a model |
599 | # try to load a model |
297 | |
600 | |
298 | for (@REGISTRY, @models) { |
601 | for (@REGISTRY, @models) { |
299 | my ($package, $model) = @$_; |
602 | my ($package, $model) = @$_; |
300 | if (eval "require $package" |
603 | if (eval "require $package" |
301 | and ${"$package\::VERSION"} > 0 |
604 | and ${"$package\::VERSION"} > 0 |
302 | and eval "require $model") { |
605 | and eval "require $model") { |
303 | $MODEL = $model; |
606 | $MODEL = $model; |
304 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
607 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
305 | last; |
608 | last; |
|
|
609 | } |
306 | } |
610 | } |
|
|
611 | |
|
|
612 | $MODEL |
|
|
613 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; |
307 | } |
614 | } |
308 | |
|
|
309 | $MODEL |
|
|
310 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event), Glib or Tk."; |
|
|
311 | } |
615 | } |
312 | |
616 | |
313 | unshift @ISA, $MODEL; |
617 | unshift @ISA, $MODEL; |
314 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
618 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
315 | } |
619 | } |
… | |
… | |
378 | our $CHLD_DELAY_W; |
682 | our $CHLD_DELAY_W; |
379 | our $PID_IDLE; |
683 | our $PID_IDLE; |
380 | our $WNOHANG; |
684 | our $WNOHANG; |
381 | |
685 | |
382 | sub _child_wait { |
686 | sub _child_wait { |
383 | while (0 <= (my $pid = waitpid -1, $WNOHANG)) { |
687 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
384 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
688 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
385 | (values %{ $PID_CB{0} || {} }); |
689 | (values %{ $PID_CB{0} || {} }); |
386 | } |
690 | } |
387 | |
691 | |
388 | undef $PID_IDLE; |
692 | undef $PID_IDLE; |
… | |
… | |
426 | undef $CHLD_W unless keys %PID_CB; |
730 | undef $CHLD_W unless keys %PID_CB; |
427 | } |
731 | } |
428 | |
732 | |
429 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
733 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
430 | |
734 | |
|
|
735 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
736 | a module. This section is only of use to event loop authors who want to |
|
|
737 | provide AnyEvent compatibility. |
|
|
738 | |
431 | If you need to support another event library which isn't directly |
739 | If you need to support another event library which isn't directly |
432 | supported by AnyEvent, you can supply your own interface to it by |
740 | supported by AnyEvent, you can supply your own interface to it by |
433 | pushing, before the first watcher gets created, the package name of |
741 | pushing, before the first watcher gets created, the package name of |
434 | the event module and the package name of the interface to use onto |
742 | the event module and the package name of the interface to use onto |
435 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
743 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
436 | AnyEvent. |
744 | AnyEvent, so it is reasonably cheap. |
437 | |
745 | |
438 | Example: |
746 | Example: |
439 | |
747 | |
440 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
748 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
441 | |
749 | |
442 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
750 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
443 | package/class when it finds the C<urxvt> package/module is loaded. When |
751 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
752 | |
444 | AnyEvent is loaded and asked to find a suitable event model, it will |
753 | When AnyEvent is loaded and asked to find a suitable event model, it |
445 | first check for the presence of urxvt. |
754 | will first check for the presence of urxvt by trying to C<use> the |
|
|
755 | C<urxvt::anyevent> module. |
446 | |
756 | |
447 | The class should provide implementations for all watcher types (see |
757 | The class should provide implementations for all watcher types. See |
448 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
758 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
449 | (Source code) and so on for actual examples, use C<perldoc -m |
759 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
450 | AnyEvent::Impl::Glib> to see the sources). |
760 | see the sources. |
451 | |
761 | |
|
|
762 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
763 | provide suitable (hopefully) replacements. |
|
|
764 | |
452 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
765 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
453 | uses the above line as-is. An interface isn't included in AnyEvent |
766 | terminal emulator uses the above line as-is. An interface isn't included |
454 | because it doesn't make sense outside the embedded interpreter inside |
767 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
455 | I<rxvt-unicode>, and it is updated and maintained as part of the |
768 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
456 | I<rxvt-unicode> distribution. |
769 | I<rxvt-unicode> distribution. |
457 | |
770 | |
458 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
771 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
459 | condition variables: code blocking while waiting for a condition will |
772 | condition variables: code blocking while waiting for a condition will |
460 | C<die>. This still works with most modules/usages, and blocking calls must |
773 | C<die>. This still works with most modules/usages, and blocking calls must |
461 | not be in an interactive application, so it makes sense. |
774 | not be done in an interactive application, so it makes sense. |
462 | |
775 | |
463 | =head1 ENVIRONMENT VARIABLES |
776 | =head1 ENVIRONMENT VARIABLES |
464 | |
777 | |
465 | The following environment variables are used by this module: |
778 | The following environment variables are used by this module: |
466 | |
779 | |
467 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
780 | =over 4 |
468 | model gets used. |
|
|
469 | |
781 | |
|
|
782 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
783 | |
|
|
784 | By default, AnyEvent will be completely silent except in fatal |
|
|
785 | conditions. You can set this environment variable to make AnyEvent more |
|
|
786 | talkative. |
|
|
787 | |
|
|
788 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
789 | conditions, such as not being able to load the event model specified by |
|
|
790 | C<PERL_ANYEVENT_MODEL>. |
|
|
791 | |
|
|
792 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
793 | model it chooses. |
|
|
794 | |
|
|
795 | =item C<PERL_ANYEVENT_MODEL> |
|
|
796 | |
|
|
797 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
798 | autodetection and -probing kicks in. It must be a string consisting |
|
|
799 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
800 | and the resulting module name is loaded and if the load was successful, |
|
|
801 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
802 | autodetection and -probing. |
|
|
803 | |
|
|
804 | This functionality might change in future versions. |
|
|
805 | |
|
|
806 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
807 | could start your program like this: |
|
|
808 | |
|
|
809 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
810 | |
|
|
811 | =back |
|
|
812 | |
470 | =head1 EXAMPLE |
813 | =head1 EXAMPLE PROGRAM |
471 | |
814 | |
472 | The following program uses an io watcher to read data from stdin, a timer |
815 | The following program uses an I/O watcher to read data from STDIN, a timer |
473 | to display a message once per second, and a condvar to exit the program |
816 | to display a message once per second, and a condition variable to quit the |
474 | when the user enters quit: |
817 | program when the user enters quit: |
475 | |
818 | |
476 | use AnyEvent; |
819 | use AnyEvent; |
477 | |
820 | |
478 | my $cv = AnyEvent->condvar; |
821 | my $cv = AnyEvent->condvar; |
479 | |
822 | |
480 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
823 | my $io_watcher = AnyEvent->io ( |
|
|
824 | fh => \*STDIN, |
|
|
825 | poll => 'r', |
|
|
826 | cb => sub { |
481 | warn "io event <$_[0]>\n"; # will always output <r> |
827 | warn "io event <$_[0]>\n"; # will always output <r> |
482 | chomp (my $input = <STDIN>); # read a line |
828 | chomp (my $input = <STDIN>); # read a line |
483 | warn "read: $input\n"; # output what has been read |
829 | warn "read: $input\n"; # output what has been read |
484 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
830 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
|
|
831 | }, |
485 | }); |
832 | ); |
486 | |
833 | |
487 | my $time_watcher; # can only be used once |
834 | my $time_watcher; # can only be used once |
488 | |
835 | |
489 | sub new_timer { |
836 | sub new_timer { |
490 | $timer = AnyEvent->timer (after => 1, cb => sub { |
837 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
572 | $txn->{finished}->wait; |
919 | $txn->{finished}->wait; |
573 | return $txn->{result}; |
920 | return $txn->{result}; |
574 | |
921 | |
575 | The actual code goes further and collects all errors (C<die>s, exceptions) |
922 | The actual code goes further and collects all errors (C<die>s, exceptions) |
576 | that occured during request processing. The C<result> method detects |
923 | that occured during request processing. The C<result> method detects |
577 | wether an exception as thrown (it is stored inside the $txn object) |
924 | whether an exception as thrown (it is stored inside the $txn object) |
578 | and just throws the exception, which means connection errors and other |
925 | and just throws the exception, which means connection errors and other |
579 | problems get reported tot he code that tries to use the result, not in a |
926 | problems get reported tot he code that tries to use the result, not in a |
580 | random callback. |
927 | random callback. |
581 | |
928 | |
582 | All of this enables the following usage styles: |
929 | All of this enables the following usage styles: |
583 | |
930 | |
584 | 1. Blocking: |
931 | 1. Blocking: |
585 | |
932 | |
586 | my $data = $fcp->client_get ($url); |
933 | my $data = $fcp->client_get ($url); |
587 | |
934 | |
588 | 2. Blocking, but parallelizing: |
935 | 2. Blocking, but running in parallel: |
589 | |
936 | |
590 | my @datas = map $_->result, |
937 | my @datas = map $_->result, |
591 | map $fcp->txn_client_get ($_), |
938 | map $fcp->txn_client_get ($_), |
592 | @urls; |
939 | @urls; |
593 | |
940 | |
594 | Both blocking examples work without the module user having to know |
941 | Both blocking examples work without the module user having to know |
595 | anything about events. |
942 | anything about events. |
596 | |
943 | |
597 | 3a. Event-based in a main program, using any support Event module: |
944 | 3a. Event-based in a main program, using any supported event module: |
598 | |
945 | |
599 | use Event; |
946 | use EV; |
600 | |
947 | |
601 | $fcp->txn_client_get ($url)->cb (sub { |
948 | $fcp->txn_client_get ($url)->cb (sub { |
602 | my $txn = shift; |
949 | my $txn = shift; |
603 | my $data = $txn->result; |
950 | my $data = $txn->result; |
604 | ... |
951 | ... |
605 | }); |
952 | }); |
606 | |
953 | |
607 | Event::loop; |
954 | EV::loop; |
608 | |
955 | |
609 | 3b. The module user could use AnyEvent, too: |
956 | 3b. The module user could use AnyEvent, too: |
610 | |
957 | |
611 | use AnyEvent; |
958 | use AnyEvent; |
612 | |
959 | |
… | |
… | |
617 | $quit->broadcast; |
964 | $quit->broadcast; |
618 | }); |
965 | }); |
619 | |
966 | |
620 | $quit->wait; |
967 | $quit->wait; |
621 | |
968 | |
|
|
969 | |
|
|
970 | =head1 BENCHMARKS |
|
|
971 | |
|
|
972 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
973 | over the event loops themselves and to give you an impression of the speed |
|
|
974 | of various event loops I prepared some benchmarks. |
|
|
975 | |
|
|
976 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
977 | |
|
|
978 | Here is a benchmark of various supported event models used natively and |
|
|
979 | through anyevent. The benchmark creates a lot of timers (with a zero |
|
|
980 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
981 | which it is), lets them fire exactly once and destroys them again. |
|
|
982 | |
|
|
983 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
984 | distribution. |
|
|
985 | |
|
|
986 | =head3 Explanation of the columns |
|
|
987 | |
|
|
988 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
989 | different event models feature vastly different performances, each event |
|
|
990 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
991 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
992 | would probably take thousands of years if asked to process the same number |
|
|
993 | of watchers as EV in this benchmark. |
|
|
994 | |
|
|
995 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
996 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
997 | and Perl-based overheads. |
|
|
998 | |
|
|
999 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1000 | takes to create a single watcher. The callback is a closure shared between |
|
|
1001 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1002 | and memory usage is not included in the figures. |
|
|
1003 | |
|
|
1004 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1005 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1006 | invoked "watcher" times, it would C<< ->broadcast >> a condvar once to |
|
|
1007 | signal the end of this phase. |
|
|
1008 | |
|
|
1009 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1010 | watcher. |
|
|
1011 | |
|
|
1012 | =head3 Results |
|
|
1013 | |
|
|
1014 | name watchers bytes create invoke destroy comment |
|
|
1015 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1016 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1017 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1018 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1019 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1020 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1021 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1022 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1023 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1024 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1025 | |
|
|
1026 | =head3 Discussion |
|
|
1027 | |
|
|
1028 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1029 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1030 | can never compete with an event loop that uses epoll when the number of |
|
|
1031 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1032 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1033 | boost. |
|
|
1034 | |
|
|
1035 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1036 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1037 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1038 | higher number of watchers at a disadvantage. |
|
|
1039 | |
|
|
1040 | To put the range of results into perspective, consider that on the |
|
|
1041 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1042 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1043 | cycles with POE. |
|
|
1044 | |
|
|
1045 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1046 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1047 | far less memory than any other event loop and is still faster than Event |
|
|
1048 | natively. |
|
|
1049 | |
|
|
1050 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1051 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1052 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1053 | adds very little overhead in itself. Like any select-based backend its |
|
|
1054 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1055 | them active), of course, but this was not subject of this benchmark. |
|
|
1056 | |
|
|
1057 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1058 | cost, but overall scores in on the third place. |
|
|
1059 | |
|
|
1060 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1061 | faster callback invocation and overall ends up in the same class as |
|
|
1062 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1063 | watchers increases the processing time by more than a factor of four, |
|
|
1064 | making it completely unusable when using larger numbers of watchers |
|
|
1065 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1066 | inefficiencies of C<poll> do not account for this). |
|
|
1067 | |
|
|
1068 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1069 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1070 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1071 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1072 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1073 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1074 | above). |
|
|
1075 | |
|
|
1076 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1077 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1078 | be tested because it wasn't working) shows abysmal performance and |
|
|
1079 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1080 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1081 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1082 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1083 | implementation. |
|
|
1084 | |
|
|
1085 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1086 | for the performance issues, though, as session creation overhead is |
|
|
1087 | small compared to execution of the state machine, which is coded pretty |
|
|
1088 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1089 | using multiple sessions is not a good approach, especially regarding |
|
|
1090 | memory usage, even the author of POE could not come up with a faster |
|
|
1091 | design). |
|
|
1092 | |
|
|
1093 | =head3 Summary |
|
|
1094 | |
|
|
1095 | =over 4 |
|
|
1096 | |
|
|
1097 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1098 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1099 | performance with or without AnyEvent. |
|
|
1100 | |
|
|
1101 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1102 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1103 | adds AnyEvent significant overhead. |
|
|
1104 | |
|
|
1105 | =item * You should avoid POE like the plague if you want performance or |
|
|
1106 | reasonable memory usage. |
|
|
1107 | |
|
|
1108 | =back |
|
|
1109 | |
|
|
1110 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1111 | |
|
|
1112 | This benchmark atcually benchmarks the event loop itself. It works by |
|
|
1113 | creating a number of "servers": each server consists of a socketpair, a |
|
|
1114 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1115 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1116 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1117 | |
|
|
1118 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1119 | are active at any one point (so there is a constant number of active |
|
|
1120 | fds for each loop iterstaion, but which fds these are is random). The |
|
|
1121 | timeout is reset each time something is read because that reflects how |
|
|
1122 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1123 | |
|
|
1124 | In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 |
|
|
1125 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1126 | connections, most of which are idle at any one point in time. |
|
|
1127 | |
|
|
1128 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1129 | distribution. |
|
|
1130 | |
|
|
1131 | =head3 Explanation of the columns |
|
|
1132 | |
|
|
1133 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1134 | each server has a read and write socket end). |
|
|
1135 | |
|
|
1136 | I<create> is the time it takes to create a socketpair (which is |
|
|
1137 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1138 | |
|
|
1139 | I<request>, the most important value, is the time it takes to handle a |
|
|
1140 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1141 | it to another server. This includes deleting the old timeout and creating |
|
|
1142 | a new one that moves the timeout into the future. |
|
|
1143 | |
|
|
1144 | =head3 Results |
|
|
1145 | |
|
|
1146 | name sockets create request |
|
|
1147 | EV 20000 69.01 11.16 |
|
|
1148 | Perl 20000 73.32 35.87 |
|
|
1149 | Event 20000 212.62 257.32 |
|
|
1150 | Glib 20000 651.16 1896.30 |
|
|
1151 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1152 | |
|
|
1153 | =head3 Discussion |
|
|
1154 | |
|
|
1155 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1156 | particular event loop. |
|
|
1157 | |
|
|
1158 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1159 | is relatively high, though. |
|
|
1160 | |
|
|
1161 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1162 | loops Event and Glib. |
|
|
1163 | |
|
|
1164 | Event suffers from high setup time as well (look at its code and you will |
|
|
1165 | understand why). Callback invocation also has a high overhead compared to |
|
|
1166 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1167 | uses select or poll in basically all documented configurations. |
|
|
1168 | |
|
|
1169 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1170 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1171 | |
|
|
1172 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1173 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1174 | it uses a C-based event loop in this case. |
|
|
1175 | |
|
|
1176 | =head3 Summary |
|
|
1177 | |
|
|
1178 | =over 4 |
|
|
1179 | |
|
|
1180 | =item * The pure perl implementation performs extremely well. |
|
|
1181 | |
|
|
1182 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1183 | |
|
|
1184 | =back |
|
|
1185 | |
|
|
1186 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1187 | |
|
|
1188 | While event loops should scale (and select-based ones do not...) even to |
|
|
1189 | large servers, most programs we (or I :) actually write have only a few |
|
|
1190 | I/O watchers. |
|
|
1191 | |
|
|
1192 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1193 | case, but it uses only eight "servers", of which three are active at any |
|
|
1194 | one time. This should reflect performance for a small server relatively |
|
|
1195 | well. |
|
|
1196 | |
|
|
1197 | The columns are identical to the previous table. |
|
|
1198 | |
|
|
1199 | =head3 Results |
|
|
1200 | |
|
|
1201 | name sockets create request |
|
|
1202 | EV 16 20.00 6.54 |
|
|
1203 | Perl 16 25.75 12.62 |
|
|
1204 | Event 16 81.27 35.86 |
|
|
1205 | Glib 16 32.63 15.48 |
|
|
1206 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1207 | |
|
|
1208 | =head3 Discussion |
|
|
1209 | |
|
|
1210 | The benchmark tries to test the performance of a typical small |
|
|
1211 | server. While knowing how various event loops perform is interesting, keep |
|
|
1212 | in mind that their overhead in this case is usually not as important, due |
|
|
1213 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1214 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1215 | them). |
|
|
1216 | |
|
|
1217 | EV is again fastest. |
|
|
1218 | |
|
|
1219 | Perl again comes second. It is noticably faster than the C-based event |
|
|
1220 | loops Event and Glib, although the difference is too small to really |
|
|
1221 | matter. |
|
|
1222 | |
|
|
1223 | POE also performs much better in this case, but is is still far behind the |
|
|
1224 | others. |
|
|
1225 | |
|
|
1226 | =head3 Summary |
|
|
1227 | |
|
|
1228 | =over 4 |
|
|
1229 | |
|
|
1230 | =item * C-based event loops perform very well with small number of |
|
|
1231 | watchers, as the management overhead dominates. |
|
|
1232 | |
|
|
1233 | =back |
|
|
1234 | |
|
|
1235 | |
|
|
1236 | =head1 FORK |
|
|
1237 | |
|
|
1238 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1239 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1240 | calls. Only L<EV> is fully fork-aware. |
|
|
1241 | |
|
|
1242 | If you have to fork, you must either do so I<before> creating your first |
|
|
1243 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1244 | |
|
|
1245 | |
|
|
1246 | =head1 SECURITY CONSIDERATIONS |
|
|
1247 | |
|
|
1248 | AnyEvent can be forced to load any event model via |
|
|
1249 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1250 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1251 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1252 | will not be active when the program uses a different event model than |
|
|
1253 | specified in the variable. |
|
|
1254 | |
|
|
1255 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1256 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1257 | |
|
|
1258 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1259 | |
|
|
1260 | use AnyEvent; |
|
|
1261 | |
|
|
1262 | |
622 | =head1 SEE ALSO |
1263 | =head1 SEE ALSO |
623 | |
1264 | |
624 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
1265 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
|
|
1266 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
|
|
1267 | L<Event::Lib>, L<Qt>, L<POE>. |
625 | |
1268 | |
|
|
1269 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
626 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
1270 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
|
|
1271 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
|
|
1272 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
627 | |
1273 | |
628 | Nontrivial usage example: L<Net::FCP>. |
1274 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
629 | |
1275 | |
630 | =head1 |
1276 | |
|
|
1277 | =head1 AUTHOR |
|
|
1278 | |
|
|
1279 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1280 | http://home.schmorp.de/ |
631 | |
1281 | |
632 | =cut |
1282 | =cut |
633 | |
1283 | |
634 | 1 |
1284 | 1 |
635 | |
1285 | |