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 ->send |
21 | $w->broadcast; # wake up current and all future wait's |
21 | $w->send; # wake up current and all future wait's |
22 | |
22 | |
23 | =head1 WHY YOU SHOULD USE THIS MODULE |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
24 | |
24 | |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
26 | nowadays. So what is different about AnyEvent? |
26 | nowadays. So what is different about AnyEvent? |
27 | |
27 | |
28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
29 | policy> and AnyEvent is I<small and efficient>. |
29 | policy> and AnyEvent is I<small and efficient>. |
30 | |
30 | |
31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
32 | interfaces to whatever event model the main program happens to use in a |
32 | interfaces to whatever event model the main program happens to use in a |
33 | pragmatic way. For event models and certain classes of immortals alike, |
33 | pragmatic way. For event models and certain classes of immortals alike, |
34 | the statement "there can only be one" is a bitter reality, and AnyEvent |
34 | the statement "there can only be one" is a bitter reality: In general, |
35 | helps hiding the differences. |
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. |
36 | |
37 | |
37 | The goal of AnyEvent is to offer module authors the ability to do event |
38 | The goal of AnyEvent is to offer module authors the ability to do event |
38 | programming (waiting for I/O or timer events) without subscribing to a |
39 | programming (waiting for I/O or timer events) without subscribing to a |
39 | religion, a way of living, and most importantly: without forcing your |
40 | religion, a way of living, and most importantly: without forcing your |
40 | module users into the same thing by forcing them to use the same event |
41 | module users into the same thing by forcing them to use the same event |
41 | model you use. |
42 | model you use. |
42 | |
43 | |
43 | For modules like POE or IO::Async (which is actually doing all I/O |
44 | For modules like POE or IO::Async (which is a total misnomer as it is |
44 | I<synchronously>...), using them in your module is like joining a |
45 | actually doing all I/O I<synchronously>...), using them in your module is |
45 | cult: After you joined, you are dependent on them and you cannot use |
46 | like joining a cult: After you joined, you are dependent on them and you |
46 | anything else, as it is simply incompatible to everything that isn't |
47 | cannot use anything else, as it is simply incompatible to everything that |
47 | itself. |
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. |
48 | |
50 | |
49 | AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk |
51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
50 | works fine etc. etc. but none of these work together with the rest: POE |
52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
51 | + IO::Async? no go. Tk + Event? no go. If your module uses one of |
53 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if |
52 | those, every user of your module has to use it, too. If your module |
54 | your module uses one of those, every user of your module has to use it, |
53 | uses AnyEvent, it works transparently with all event models it supports |
55 | too. But if your module uses AnyEvent, it works transparently with all |
54 | (including stuff like POE and IO::Async). |
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). |
55 | |
59 | |
56 | In addition of being free of having to use I<the one and only true event |
60 | In addition to being free of having to use I<the one and only true event |
57 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
58 | modules, you get an enourmous amount of code and strict rules you have |
62 | modules, you get an enourmous amount of code and strict rules you have to |
59 | to follow. AnyEvent, on the other hand, is lean and to the point by only |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
60 | offering the functionality that is useful, in as thin as a wrapper as |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
61 | technically possible. |
65 | technically possible. |
62 | |
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. |
63 | |
70 | |
64 | =head1 DESCRIPTION |
71 | =head1 DESCRIPTION |
65 | |
72 | |
66 | L<AnyEvent> provides an identical interface to multiple event loops. This |
73 | L<AnyEvent> provides an identical interface to multiple event loops. This |
67 | allows module authors to utilise an event loop without forcing module |
74 | allows module authors to utilise an event loop without forcing module |
68 | 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 |
69 | peacefully at any one time). |
76 | peacefully at any one time). |
70 | |
77 | |
71 | 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> |
72 | module. |
79 | module. |
73 | |
80 | |
74 | 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 |
75 | 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 |
76 | 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>, |
77 | 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>, |
78 | 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 |
79 | 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 |
80 | 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. |
81 | |
91 | |
82 | Because AnyEvent first checks for modules that are already loaded, loading |
92 | Because AnyEvent first checks for modules that are already loaded, loading |
83 | an Event model explicitly before first using AnyEvent will likely make |
93 | an event model explicitly before first using AnyEvent will likely make |
84 | that model the default. For example: |
94 | that model the default. For example: |
85 | |
95 | |
86 | use Tk; |
96 | use Tk; |
87 | use AnyEvent; |
97 | use AnyEvent; |
88 | |
98 | |
89 | # .. 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... |
90 | |
104 | |
91 | The pure-perl implementation of AnyEvent is called |
105 | The pure-perl implementation of AnyEvent is called |
92 | 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 |
93 | explicitly. |
107 | explicitly. |
94 | |
108 | |
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97 | 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 |
98 | 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 |
99 | the callback to call, the filehandle to watch, etc. |
113 | the callback to call, the filehandle to watch, etc. |
100 | |
114 | |
101 | These watchers are normal Perl objects with normal Perl lifetime. After |
115 | These watchers are normal Perl objects with normal Perl lifetime. After |
102 | 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 | |
103 | 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 |
104 | 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 |
105 | references to it). |
122 | to it). |
106 | |
123 | |
107 | 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. |
108 | |
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 | |
109 | =head2 IO WATCHERS |
140 | =head2 I/O WATCHERS |
110 | |
141 | |
111 | 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 |
112 | the following mandatory arguments: |
143 | with the following mandatory key-value pairs as arguments: |
113 | |
144 | |
114 | 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 |
115 | 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>, |
116 | 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, |
117 | 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. |
118 | |
150 | |
119 | 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 |
120 | 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 |
121 | 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. |
122 | |
154 | |
123 | 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. |
124 | 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. |
125 | |
162 | |
126 | Example: |
163 | Example: |
127 | |
164 | |
128 | # 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 |
129 | 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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135 | =head2 TIME WATCHERS |
172 | =head2 TIME WATCHERS |
136 | |
173 | |
137 | 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 >> |
138 | method with the following mandatory arguments: |
175 | method with the following mandatory arguments: |
139 | |
176 | |
140 | C<after> after how many seconds (fractions are supported) should the timer |
177 | C<after> specifies after how many seconds (fractional values are |
141 | 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. |
142 | |
184 | |
143 | 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 |
144 | 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 |
145 | and Glib). |
187 | and Glib). |
146 | |
188 | |
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152 | }); |
194 | }); |
153 | |
195 | |
154 | # to cancel the timer: |
196 | # to cancel the timer: |
155 | undef $w; |
197 | undef $w; |
156 | |
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->send; |
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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 | |
157 | =head2 CONDITION WATCHERS |
300 | =head2 CONDITION VARIABLES |
158 | |
301 | |
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302 | If you are familiar with some event loops you will know that all of them |
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303 | require you to run some blocking "loop", "run" or similar function that |
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304 | will actively watch for new events and call your callbacks. |
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305 | |
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306 | AnyEvent is different, it expects somebody else to run the event loop and |
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307 | will only block when necessary (usually when told by the user). |
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308 | |
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309 | The instrument to do that is called a "condition variable", so called |
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310 | because they represent a condition that must become true. |
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311 | |
159 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
312 | Condition variables can be created by calling the C<< AnyEvent->condvar |
160 | method without any arguments. |
313 | >> method, usually without arguments. The only argument pair allowed is |
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314 | C<cb>, which specifies a callback to be called when the condition variable |
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315 | becomes true. |
161 | |
316 | |
162 | A condition watcher watches for a condition - precisely that the C<< |
317 | After creation, the conditon variable is "false" until it becomes "true" |
163 | ->broadcast >> method has been called. |
318 | by calling the C<send> method. |
164 | |
319 | |
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320 | Condition variables are similar to callbacks, except that you can |
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321 | optionally wait for them. They can also be called merge points - points |
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322 | in time where multiple outstandign events have been processed. And yet |
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323 | another way to call them is transations - each condition variable can be |
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324 | used to represent a transaction, which finishes at some point and delivers |
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325 | a result. |
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326 | |
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327 | Condition variables are very useful to signal that something has finished, |
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328 | for example, if you write a module that does asynchronous http requests, |
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329 | then a condition variable would be the ideal candidate to signal the |
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330 | availability of results. The user can either act when the callback is |
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331 | called or can synchronously C<< ->wait >> for the results. |
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332 | |
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333 | You can also use them to simulate traditional event loops - for example, |
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334 | you can block your main program until an event occurs - for example, you |
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335 | could C<< ->wait >> in your main program until the user clicks the Quit |
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336 | button of your app, which would C<< ->send >> the "quit" event. |
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337 | |
165 | Note that condition watchers recurse into the event loop - if you have |
338 | Note that condition variables recurse into the event loop - if you have |
166 | two watchers that call C<< ->wait >> in a round-robbin fashion, you |
339 | two pieces of code that call C<< ->wait >> in a round-robbin fashion, you |
167 | lose. Therefore, condition watchers are good to export to your caller, but |
340 | lose. Therefore, condition variables are good to export to your caller, but |
168 | you should avoid making a blocking wait, at least in callbacks, as this |
341 | you should avoid making a blocking wait yourself, at least in callbacks, |
169 | usually asks for trouble. |
342 | as this asks for trouble. |
170 | |
343 | |
171 | The watcher has only two methods: |
344 | Condition variables are represented by hash refs in perl, and the keys |
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345 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
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346 | easy (it is often useful to build your own transaction class on top of |
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347 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
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348 | it's C<new> method in your own C<new> method. |
172 | |
349 | |
173 | =over 4 |
350 | There are two "sides" to a condition variable - the "producer side" which |
174 | |
351 | eventually calls C<< -> send >>, and the "consumer side", which waits |
175 | =item $cv->wait |
352 | for the send to occur. |
176 | |
|
|
177 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
|
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178 | called on c<$cv>, while servicing other watchers normally. |
|
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179 | |
|
|
180 | Not all event models support a blocking wait - some die in that case, so |
|
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181 | if you are using this from a module, never require a blocking wait, but |
|
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182 | let the caller decide wether the call will block or not (for example, |
|
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183 | by coupling condition variables with some kind of request results and |
|
|
184 | supporting callbacks so the caller knows that getting the result will not |
|
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185 | block, while still suppporting blockign waits if the caller so desires). |
|
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186 | |
|
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187 | You can only wait once on a condition - additional calls will return |
|
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188 | immediately. |
|
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189 | |
|
|
190 | =item $cv->broadcast |
|
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191 | |
|
|
192 | Flag the condition as ready - a running C<< ->wait >> and all further |
|
|
193 | calls to C<wait> will return after this method has been called. If nobody |
|
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194 | is waiting the broadcast will be remembered.. |
|
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195 | |
353 | |
196 | Example: |
354 | Example: |
197 | |
355 | |
198 | # wait till the result is ready |
356 | # wait till the result is ready |
199 | my $result_ready = AnyEvent->condvar; |
357 | my $result_ready = AnyEvent->condvar; |
200 | |
358 | |
201 | # do something such as adding a timer |
359 | # do something such as adding a timer |
202 | # or socket watcher the calls $result_ready->broadcast |
360 | # or socket watcher the calls $result_ready->send |
203 | # when the "result" is ready. |
361 | # when the "result" is ready. |
|
|
362 | # in this case, we simply use a timer: |
|
|
363 | my $w = AnyEvent->timer ( |
|
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364 | after => 1, |
|
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365 | cb => sub { $result_ready->send }, |
|
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366 | ); |
204 | |
367 | |
|
|
368 | # this "blocks" (while handling events) till the callback |
|
|
369 | # calls send |
205 | $result_ready->wait; |
370 | $result_ready->wait; |
206 | |
371 | |
|
|
372 | =head3 METHODS FOR PRODUCERS |
|
|
373 | |
|
|
374 | These methods should only be used by the producing side, i.e. the |
|
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375 | code/module that eventually sends the signal. Note that it is also |
|
|
376 | the producer side which creates the condvar in most cases, but it isn't |
|
|
377 | uncommon for the consumer to create it as well. |
|
|
378 | |
|
|
379 | =over 4 |
|
|
380 | |
|
|
381 | =item $cv->send (...) |
|
|
382 | |
|
|
383 | Flag the condition as ready - a running C<< ->wait >> and all further |
|
|
384 | calls to C<wait> will (eventually) return after this method has been |
|
|
385 | called. If nobody is waiting the send will be remembered. |
|
|
386 | |
|
|
387 | If a callback has been set on the condition variable, it is called |
|
|
388 | immediately from within send. |
|
|
389 | |
|
|
390 | Any arguments passed to the C<send> call will be returned by all |
|
|
391 | future C<< ->wait >> calls. |
|
|
392 | |
|
|
393 | =item $cv->croak ($error) |
|
|
394 | |
|
|
395 | Similar to send, but causes all call's wait C<< ->wait >> to invoke |
|
|
396 | C<Carp::croak> with the given error message/object/scalar. |
|
|
397 | |
|
|
398 | This can be used to signal any errors to the condition variable |
|
|
399 | user/consumer. |
|
|
400 | |
|
|
401 | =item $cv->begin ([group callback]) |
|
|
402 | |
|
|
403 | =item $cv->end |
|
|
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 eahc subrequest you finish, call C<end>. |
|
|
449 | |
207 | =back |
450 | =back |
208 | |
451 | |
209 | =head2 SIGNAL WATCHERS |
452 | =head3 METHODS FOR CONSUMERS |
210 | |
453 | |
211 | 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 |
212 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
455 | code awaits the condition. |
213 | together into one callback invocation, and callback invocation might or |
|
|
214 | might not be asynchronous. |
|
|
215 | |
456 | |
216 | These watchers might use C<%SIG>, so programs overwriting those signals |
457 | =over 4 |
217 | directly will likely not work correctly. |
|
|
218 | |
458 | |
219 | Example: exit on SIGINT |
459 | =item $cv->wait |
220 | |
460 | |
221 | 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. |
222 | |
464 | |
223 | =head2 CHILD PROCESS WATCHERS |
465 | You can only wait once on a condition - additional calls are valid but |
|
|
466 | will return immediately. |
224 | |
467 | |
225 | 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 |
226 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
469 | function will call C<croak>. |
227 | trigger as often as status change for the child are received. This works |
|
|
228 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
|
|
229 | the pid and exit status (as returned by waitpid). |
|
|
230 | |
470 | |
231 | 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. |
232 | |
473 | |
233 | 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 suppporting blocking waits if the caller so desires). |
234 | |
481 | |
235 | =head1 GLOBALS |
482 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
|
|
483 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
|
|
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
|
|
485 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
|
|
486 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
|
|
487 | from different coroutines, however). |
|
|
488 | |
|
|
489 | You can ensure that C<< -wait >> never blocks by setting a callback and |
|
|
490 | only calling C<< ->wait >> from within that callback (or at a later |
|
|
491 | time). This will work even when the event loop does not support blocking |
|
|
492 | waits otherwise. |
|
|
493 | |
|
|
494 | =item $bool = $cv->ready |
|
|
495 | |
|
|
496 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
497 | C<croak> have been called. |
|
|
498 | |
|
|
499 | =item $cb = $cv->cb ([new callback]) |
|
|
500 | |
|
|
501 | This is a mutator function that returns the callback set and optionally |
|
|
502 | replaces it before doing so. |
|
|
503 | |
|
|
504 | The callback will be called when the condition becomes "true", i.e. when |
|
|
505 | C<send> or C<croak> are called. Calling C<wait> inside the callback |
|
|
506 | or at any later time is guaranteed not to block. |
|
|
507 | |
|
|
508 | =back |
|
|
509 | |
|
|
510 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
236 | |
511 | |
237 | =over 4 |
512 | =over 4 |
238 | |
513 | |
239 | =item $AnyEvent::MODEL |
514 | =item $AnyEvent::MODEL |
240 | |
515 | |
… | |
… | |
245 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
520 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
246 | |
521 | |
247 | The known classes so far are: |
522 | The known classes so far are: |
248 | |
523 | |
249 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
524 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
250 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
|
|
251 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
525 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
|
|
526 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
252 | AnyEvent::Impl::Event based on Event, also second best choice :) |
527 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
528 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
253 | AnyEvent::Impl::Glib based on Glib, second-best choice. |
529 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
254 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
530 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
255 | AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
531 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
532 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
533 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
534 | |
|
|
535 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
536 | watching file handles. However, you can use WxWidgets through the |
|
|
537 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
538 | second, which was considered to be too horrible to even consider for |
|
|
539 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
540 | it's adaptor. |
|
|
541 | |
|
|
542 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
543 | autodetecting them. |
256 | |
544 | |
257 | =item AnyEvent::detect |
545 | =item AnyEvent::detect |
258 | |
546 | |
259 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
547 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
260 | necessary. You should only call this function right before you would have |
548 | if necessary. You should only call this function right before you would |
261 | created an AnyEvent watcher anyway, that is, very late at runtime. |
549 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
550 | runtime. |
262 | |
551 | |
263 | =back |
552 | =back |
264 | |
553 | |
265 | =head1 WHAT TO DO IN A MODULE |
554 | =head1 WHAT TO DO IN A MODULE |
266 | |
555 | |
267 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
556 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
268 | freely, but you should not load a specific event module or rely on it. |
557 | freely, but you should not load a specific event module or rely on it. |
269 | |
558 | |
270 | Be careful when you create watchers in the module body - Anyevent will |
559 | Be careful when you create watchers in the module body - AnyEvent will |
271 | decide which event module to use as soon as the first method is called, so |
560 | decide which event module to use as soon as the first method is called, so |
272 | by calling AnyEvent in your module body you force the user of your module |
561 | by calling AnyEvent in your module body you force the user of your module |
273 | to load the event module first. |
562 | to load the event module first. |
274 | |
563 | |
|
|
564 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
|
|
565 | the C<< ->send >> method has been called on it already. This is |
|
|
566 | because it will stall the whole program, and the whole point of using |
|
|
567 | events is to stay interactive. |
|
|
568 | |
|
|
569 | It is fine, however, to call C<< ->wait >> when the user of your module |
|
|
570 | requests it (i.e. if you create a http request object ad have a method |
|
|
571 | called C<results> that returns the results, it should call C<< ->wait >> |
|
|
572 | freely, as the user of your module knows what she is doing. always). |
|
|
573 | |
275 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
574 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
276 | |
575 | |
277 | There will always be a single main program - the only place that should |
576 | There will always be a single main program - the only place that should |
278 | dictate which event model to use. |
577 | dictate which event model to use. |
279 | |
578 | |
280 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
579 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
281 | do anything special and let AnyEvent decide which implementation to chose. |
580 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
581 | decide which implementation to chose if some module relies on it. |
282 | |
582 | |
283 | If the main program relies on a specific event model (for example, in Gtk2 |
583 | If the main program relies on a specific event model. For example, in |
284 | programs you have to rely on either Glib or Glib::Event), you should load |
584 | Gtk2 programs you have to rely on the Glib module. You should load the |
285 | it before loading AnyEvent or any module that uses it, generally, as early |
585 | event module before loading AnyEvent or any module that uses it: generally |
286 | as possible. The reason is that modules might create watchers when they |
586 | speaking, you should load it as early as possible. The reason is that |
287 | are loaded, and AnyEvent will decide on the event model to use as soon as |
587 | modules might create watchers when they are loaded, and AnyEvent will |
288 | it creates watchers, and it might chose the wrong one unless you load the |
588 | decide on the event model to use as soon as it creates watchers, and it |
289 | correct one yourself. |
589 | might chose the wrong one unless you load the correct one yourself. |
290 | |
590 | |
291 | You can chose to use a rather inefficient pure-perl implementation by |
591 | You can chose to use a rather inefficient pure-perl implementation by |
292 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
592 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
293 | generally better. |
593 | behaviour everywhere, but letting AnyEvent chose is generally better. |
|
|
594 | |
|
|
595 | =head1 OTHER MODULES |
|
|
596 | |
|
|
597 | The following is a non-exhaustive list of additional modules that use |
|
|
598 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
599 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
600 | available via CPAN. |
|
|
601 | |
|
|
602 | =over 4 |
|
|
603 | |
|
|
604 | =item L<AnyEvent::Util> |
|
|
605 | |
|
|
606 | Contains various utility functions that replace often-used but blocking |
|
|
607 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
608 | |
|
|
609 | =item L<AnyEvent::Handle> |
|
|
610 | |
|
|
611 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
612 | |
|
|
613 | =item L<AnyEvent::Socket> |
|
|
614 | |
|
|
615 | Provides a means to do non-blocking connects, accepts etc. |
|
|
616 | |
|
|
617 | =item L<AnyEvent::HTTPD> |
|
|
618 | |
|
|
619 | Provides a simple web application server framework. |
|
|
620 | |
|
|
621 | =item L<AnyEvent::DNS> |
|
|
622 | |
|
|
623 | Provides asynchronous DNS resolver capabilities, beyond what |
|
|
624 | L<AnyEvent::Util> offers. |
|
|
625 | |
|
|
626 | =item L<AnyEvent::FastPing> |
|
|
627 | |
|
|
628 | The fastest ping in the west. |
|
|
629 | |
|
|
630 | =item L<Net::IRC3> |
|
|
631 | |
|
|
632 | AnyEvent based IRC client module family. |
|
|
633 | |
|
|
634 | =item L<Net::XMPP2> |
|
|
635 | |
|
|
636 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
637 | |
|
|
638 | =item L<Net::FCP> |
|
|
639 | |
|
|
640 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
641 | of AnyEvent. |
|
|
642 | |
|
|
643 | =item L<Event::ExecFlow> |
|
|
644 | |
|
|
645 | High level API for event-based execution flow control. |
|
|
646 | |
|
|
647 | =item L<Coro> |
|
|
648 | |
|
|
649 | Has special support for AnyEvent. |
|
|
650 | |
|
|
651 | =item L<IO::Lambda> |
|
|
652 | |
|
|
653 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
654 | |
|
|
655 | =item L<IO::AIO> |
|
|
656 | |
|
|
657 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
658 | programmer. Can be trivially made to use AnyEvent. |
|
|
659 | |
|
|
660 | =item L<BDB> |
|
|
661 | |
|
|
662 | Truly asynchronous Berkeley DB access. Can be trivially made to use |
|
|
663 | AnyEvent. |
|
|
664 | |
|
|
665 | =back |
294 | |
666 | |
295 | =cut |
667 | =cut |
296 | |
668 | |
297 | package AnyEvent; |
669 | package AnyEvent; |
298 | |
670 | |
299 | no warnings; |
671 | no warnings; |
300 | use strict; |
672 | use strict; |
301 | |
673 | |
302 | use Carp; |
674 | use Carp; |
303 | |
675 | |
304 | our $VERSION = '3.0'; |
676 | our $VERSION = '3.3'; |
305 | our $MODEL; |
677 | our $MODEL; |
306 | |
678 | |
307 | our $AUTOLOAD; |
679 | our $AUTOLOAD; |
308 | our @ISA; |
680 | our @ISA; |
309 | |
681 | |
… | |
… | |
311 | |
683 | |
312 | our @REGISTRY; |
684 | our @REGISTRY; |
313 | |
685 | |
314 | my @models = ( |
686 | my @models = ( |
315 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
687 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
688 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
316 | [EV:: => AnyEvent::Impl::EV::], |
689 | [EV:: => AnyEvent::Impl::EV::], |
317 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
318 | [Event:: => AnyEvent::Impl::Event::], |
690 | [Event:: => AnyEvent::Impl::Event::], |
|
|
691 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
692 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
693 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
694 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
695 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
319 | [Glib:: => AnyEvent::Impl::Glib::], |
696 | [Glib:: => AnyEvent::Impl::Glib::], |
320 | [Tk:: => AnyEvent::Impl::Tk::], |
697 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
321 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
698 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
699 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
322 | ); |
700 | ); |
323 | |
701 | |
324 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
702 | our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); |
325 | |
703 | |
326 | sub detect() { |
704 | sub detect() { |
327 | unless ($MODEL) { |
705 | unless ($MODEL) { |
328 | no strict 'refs'; |
706 | no strict 'refs'; |
329 | |
707 | |
|
|
708 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
709 | my $model = "AnyEvent::Impl::$1"; |
|
|
710 | if (eval "require $model") { |
|
|
711 | $MODEL = $model; |
|
|
712 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
713 | } else { |
|
|
714 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
715 | } |
|
|
716 | } |
|
|
717 | |
330 | # check for already loaded models |
718 | # check for already loaded models |
|
|
719 | unless ($MODEL) { |
331 | for (@REGISTRY, @models) { |
720 | for (@REGISTRY, @models) { |
332 | my ($package, $model) = @$_; |
721 | my ($package, $model) = @$_; |
333 | if (${"$package\::VERSION"} > 0) { |
722 | if (${"$package\::VERSION"} > 0) { |
334 | if (eval "require $model") { |
723 | if (eval "require $model") { |
335 | $MODEL = $model; |
724 | $MODEL = $model; |
336 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
725 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
337 | last; |
726 | last; |
|
|
727 | } |
338 | } |
728 | } |
339 | } |
729 | } |
340 | } |
|
|
341 | |
730 | |
342 | unless ($MODEL) { |
731 | unless ($MODEL) { |
343 | # try to load a model |
732 | # try to load a model |
344 | |
733 | |
345 | for (@REGISTRY, @models) { |
734 | for (@REGISTRY, @models) { |
346 | my ($package, $model) = @$_; |
735 | my ($package, $model) = @$_; |
347 | if (eval "require $package" |
736 | if (eval "require $package" |
348 | and ${"$package\::VERSION"} > 0 |
737 | and ${"$package\::VERSION"} > 0 |
349 | and eval "require $model") { |
738 | and eval "require $model") { |
350 | $MODEL = $model; |
739 | $MODEL = $model; |
351 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
740 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
352 | last; |
741 | last; |
|
|
742 | } |
353 | } |
743 | } |
|
|
744 | |
|
|
745 | $MODEL |
|
|
746 | 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."; |
354 | } |
747 | } |
355 | |
|
|
356 | $MODEL |
|
|
357 | 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."; |
|
|
358 | } |
748 | } |
359 | |
749 | |
360 | unshift @ISA, $MODEL; |
750 | unshift @ISA, $MODEL; |
361 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
751 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
362 | } |
752 | } |
… | |
… | |
473 | undef $CHLD_W unless keys %PID_CB; |
863 | undef $CHLD_W unless keys %PID_CB; |
474 | } |
864 | } |
475 | |
865 | |
476 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
866 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
477 | |
867 | |
|
|
868 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
869 | a module. This section is only of use to event loop authors who want to |
|
|
870 | provide AnyEvent compatibility. |
|
|
871 | |
478 | If you need to support another event library which isn't directly |
872 | If you need to support another event library which isn't directly |
479 | supported by AnyEvent, you can supply your own interface to it by |
873 | supported by AnyEvent, you can supply your own interface to it by |
480 | pushing, before the first watcher gets created, the package name of |
874 | pushing, before the first watcher gets created, the package name of |
481 | the event module and the package name of the interface to use onto |
875 | the event module and the package name of the interface to use onto |
482 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
876 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
483 | AnyEvent. |
877 | AnyEvent, so it is reasonably cheap. |
484 | |
878 | |
485 | Example: |
879 | Example: |
486 | |
880 | |
487 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
881 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
488 | |
882 | |
489 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
883 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
490 | package/class when it finds the C<urxvt> package/module is loaded. When |
884 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
885 | |
491 | AnyEvent is loaded and asked to find a suitable event model, it will |
886 | When AnyEvent is loaded and asked to find a suitable event model, it |
492 | first check for the presence of urxvt. |
887 | will first check for the presence of urxvt by trying to C<use> the |
|
|
888 | C<urxvt::anyevent> module. |
493 | |
889 | |
494 | The class should provide implementations for all watcher types (see |
890 | The class should provide implementations for all watcher types. See |
495 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
891 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
496 | (Source code) and so on for actual examples, use C<perldoc -m |
892 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
497 | AnyEvent::Impl::Glib> to see the sources). |
893 | see the sources. |
498 | |
894 | |
|
|
895 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
896 | provide suitable (hopefully) replacements. |
|
|
897 | |
499 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
898 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
500 | uses the above line as-is. An interface isn't included in AnyEvent |
899 | terminal emulator uses the above line as-is. An interface isn't included |
501 | because it doesn't make sense outside the embedded interpreter inside |
900 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
502 | I<rxvt-unicode>, and it is updated and maintained as part of the |
901 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
503 | I<rxvt-unicode> distribution. |
902 | I<rxvt-unicode> distribution. |
504 | |
903 | |
505 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
904 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
506 | condition variables: code blocking while waiting for a condition will |
905 | condition variables: code blocking while waiting for a condition will |
507 | C<die>. This still works with most modules/usages, and blocking calls must |
906 | C<die>. This still works with most modules/usages, and blocking calls must |
508 | not be in an interactive application, so it makes sense. |
907 | not be done in an interactive application, so it makes sense. |
509 | |
908 | |
510 | =head1 ENVIRONMENT VARIABLES |
909 | =head1 ENVIRONMENT VARIABLES |
511 | |
910 | |
512 | The following environment variables are used by this module: |
911 | The following environment variables are used by this module: |
513 | |
912 | |
514 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
913 | =over 4 |
515 | model gets used. |
|
|
516 | |
914 | |
|
|
915 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
916 | |
|
|
917 | By default, AnyEvent will be completely silent except in fatal |
|
|
918 | conditions. You can set this environment variable to make AnyEvent more |
|
|
919 | talkative. |
|
|
920 | |
|
|
921 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
922 | conditions, such as not being able to load the event model specified by |
|
|
923 | C<PERL_ANYEVENT_MODEL>. |
|
|
924 | |
|
|
925 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
926 | model it chooses. |
|
|
927 | |
|
|
928 | =item C<PERL_ANYEVENT_MODEL> |
|
|
929 | |
|
|
930 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
931 | autodetection and -probing kicks in. It must be a string consisting |
|
|
932 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
933 | and the resulting module name is loaded and if the load was successful, |
|
|
934 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
935 | autodetection and -probing. |
|
|
936 | |
|
|
937 | This functionality might change in future versions. |
|
|
938 | |
|
|
939 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
940 | could start your program like this: |
|
|
941 | |
|
|
942 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
943 | |
|
|
944 | =back |
|
|
945 | |
517 | =head1 EXAMPLE |
946 | =head1 EXAMPLE PROGRAM |
518 | |
947 | |
519 | The following program uses an io watcher to read data from stdin, a timer |
948 | The following program uses an I/O watcher to read data from STDIN, a timer |
520 | to display a message once per second, and a condvar to exit the program |
949 | to display a message once per second, and a condition variable to quit the |
521 | when the user enters quit: |
950 | program when the user enters quit: |
522 | |
951 | |
523 | use AnyEvent; |
952 | use AnyEvent; |
524 | |
953 | |
525 | my $cv = AnyEvent->condvar; |
954 | my $cv = AnyEvent->condvar; |
526 | |
955 | |
527 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
956 | my $io_watcher = AnyEvent->io ( |
|
|
957 | fh => \*STDIN, |
|
|
958 | poll => 'r', |
|
|
959 | cb => sub { |
528 | warn "io event <$_[0]>\n"; # will always output <r> |
960 | warn "io event <$_[0]>\n"; # will always output <r> |
529 | chomp (my $input = <STDIN>); # read a line |
961 | chomp (my $input = <STDIN>); # read a line |
530 | warn "read: $input\n"; # output what has been read |
962 | warn "read: $input\n"; # output what has been read |
531 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
963 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
|
|
964 | }, |
532 | }); |
965 | ); |
533 | |
966 | |
534 | my $time_watcher; # can only be used once |
967 | my $time_watcher; # can only be used once |
535 | |
968 | |
536 | sub new_timer { |
969 | sub new_timer { |
537 | $timer = AnyEvent->timer (after => 1, cb => sub { |
970 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
619 | $txn->{finished}->wait; |
1052 | $txn->{finished}->wait; |
620 | return $txn->{result}; |
1053 | return $txn->{result}; |
621 | |
1054 | |
622 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1055 | The actual code goes further and collects all errors (C<die>s, exceptions) |
623 | that occured during request processing. The C<result> method detects |
1056 | that occured during request processing. The C<result> method detects |
624 | wether an exception as thrown (it is stored inside the $txn object) |
1057 | whether an exception as thrown (it is stored inside the $txn object) |
625 | and just throws the exception, which means connection errors and other |
1058 | and just throws the exception, which means connection errors and other |
626 | problems get reported tot he code that tries to use the result, not in a |
1059 | problems get reported tot he code that tries to use the result, not in a |
627 | random callback. |
1060 | random callback. |
628 | |
1061 | |
629 | All of this enables the following usage styles: |
1062 | All of this enables the following usage styles: |
630 | |
1063 | |
631 | 1. Blocking: |
1064 | 1. Blocking: |
632 | |
1065 | |
633 | my $data = $fcp->client_get ($url); |
1066 | my $data = $fcp->client_get ($url); |
634 | |
1067 | |
635 | 2. Blocking, but parallelizing: |
1068 | 2. Blocking, but running in parallel: |
636 | |
1069 | |
637 | my @datas = map $_->result, |
1070 | my @datas = map $_->result, |
638 | map $fcp->txn_client_get ($_), |
1071 | map $fcp->txn_client_get ($_), |
639 | @urls; |
1072 | @urls; |
640 | |
1073 | |
641 | Both blocking examples work without the module user having to know |
1074 | Both blocking examples work without the module user having to know |
642 | anything about events. |
1075 | anything about events. |
643 | |
1076 | |
644 | 3a. Event-based in a main program, using any support Event module: |
1077 | 3a. Event-based in a main program, using any supported event module: |
645 | |
1078 | |
646 | use Event; |
1079 | use EV; |
647 | |
1080 | |
648 | $fcp->txn_client_get ($url)->cb (sub { |
1081 | $fcp->txn_client_get ($url)->cb (sub { |
649 | my $txn = shift; |
1082 | my $txn = shift; |
650 | my $data = $txn->result; |
1083 | my $data = $txn->result; |
651 | ... |
1084 | ... |
652 | }); |
1085 | }); |
653 | |
1086 | |
654 | Event::loop; |
1087 | EV::loop; |
655 | |
1088 | |
656 | 3b. The module user could use AnyEvent, too: |
1089 | 3b. The module user could use AnyEvent, too: |
657 | |
1090 | |
658 | use AnyEvent; |
1091 | use AnyEvent; |
659 | |
1092 | |
… | |
… | |
664 | $quit->broadcast; |
1097 | $quit->broadcast; |
665 | }); |
1098 | }); |
666 | |
1099 | |
667 | $quit->wait; |
1100 | $quit->wait; |
668 | |
1101 | |
|
|
1102 | |
|
|
1103 | =head1 BENCHMARKS |
|
|
1104 | |
|
|
1105 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1106 | over the event loops themselves and to give you an impression of the speed |
|
|
1107 | of various event loops I prepared some benchmarks. |
|
|
1108 | |
|
|
1109 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1110 | |
|
|
1111 | Here is a benchmark of various supported event models used natively and |
|
|
1112 | through anyevent. The benchmark creates a lot of timers (with a zero |
|
|
1113 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1114 | which it is), lets them fire exactly once and destroys them again. |
|
|
1115 | |
|
|
1116 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1117 | distribution. |
|
|
1118 | |
|
|
1119 | =head3 Explanation of the columns |
|
|
1120 | |
|
|
1121 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1122 | different event models feature vastly different performances, each event |
|
|
1123 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1124 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1125 | would probably take thousands of years if asked to process the same number |
|
|
1126 | of watchers as EV in this benchmark. |
|
|
1127 | |
|
|
1128 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1129 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1130 | and Perl-based overheads. |
|
|
1131 | |
|
|
1132 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1133 | takes to create a single watcher. The callback is a closure shared between |
|
|
1134 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1135 | and memory usage is not included in the figures. |
|
|
1136 | |
|
|
1137 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1138 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1139 | invoked "watcher" times, it would C<< ->broadcast >> a condvar once to |
|
|
1140 | signal the end of this phase. |
|
|
1141 | |
|
|
1142 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1143 | watcher. |
|
|
1144 | |
|
|
1145 | =head3 Results |
|
|
1146 | |
|
|
1147 | name watchers bytes create invoke destroy comment |
|
|
1148 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1149 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1150 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1151 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1152 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1153 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1154 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1155 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1156 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1157 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1158 | |
|
|
1159 | =head3 Discussion |
|
|
1160 | |
|
|
1161 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1162 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1163 | can never compete with an event loop that uses epoll when the number of |
|
|
1164 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1165 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1166 | boost. |
|
|
1167 | |
|
|
1168 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1169 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1170 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1171 | higher number of watchers at a disadvantage. |
|
|
1172 | |
|
|
1173 | To put the range of results into perspective, consider that on the |
|
|
1174 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1175 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1176 | cycles with POE. |
|
|
1177 | |
|
|
1178 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1179 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1180 | far less memory than any other event loop and is still faster than Event |
|
|
1181 | natively. |
|
|
1182 | |
|
|
1183 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1184 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1185 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1186 | adds very little overhead in itself. Like any select-based backend its |
|
|
1187 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1188 | them active), of course, but this was not subject of this benchmark. |
|
|
1189 | |
|
|
1190 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1191 | cost, but overall scores in on the third place. |
|
|
1192 | |
|
|
1193 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1194 | faster callback invocation and overall ends up in the same class as |
|
|
1195 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1196 | watchers increases the processing time by more than a factor of four, |
|
|
1197 | making it completely unusable when using larger numbers of watchers |
|
|
1198 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1199 | inefficiencies of C<poll> do not account for this). |
|
|
1200 | |
|
|
1201 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1202 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1203 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1204 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1205 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1206 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1207 | above). |
|
|
1208 | |
|
|
1209 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1210 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1211 | be tested because it wasn't working) shows abysmal performance and |
|
|
1212 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1213 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1214 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1215 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1216 | implementation. |
|
|
1217 | |
|
|
1218 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1219 | for the performance issues, though, as session creation overhead is |
|
|
1220 | small compared to execution of the state machine, which is coded pretty |
|
|
1221 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1222 | using multiple sessions is not a good approach, especially regarding |
|
|
1223 | memory usage, even the author of POE could not come up with a faster |
|
|
1224 | design). |
|
|
1225 | |
|
|
1226 | =head3 Summary |
|
|
1227 | |
|
|
1228 | =over 4 |
|
|
1229 | |
|
|
1230 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1231 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1232 | performance with or without AnyEvent. |
|
|
1233 | |
|
|
1234 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1235 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1236 | adds AnyEvent significant overhead. |
|
|
1237 | |
|
|
1238 | =item * You should avoid POE like the plague if you want performance or |
|
|
1239 | reasonable memory usage. |
|
|
1240 | |
|
|
1241 | =back |
|
|
1242 | |
|
|
1243 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1244 | |
|
|
1245 | This benchmark atcually benchmarks the event loop itself. It works by |
|
|
1246 | creating a number of "servers": each server consists of a socketpair, a |
|
|
1247 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1248 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1249 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1250 | |
|
|
1251 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1252 | are active at any one point (so there is a constant number of active |
|
|
1253 | fds for each loop iterstaion, but which fds these are is random). The |
|
|
1254 | timeout is reset each time something is read because that reflects how |
|
|
1255 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1256 | |
|
|
1257 | In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 |
|
|
1258 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1259 | connections, most of which are idle at any one point in time. |
|
|
1260 | |
|
|
1261 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1262 | distribution. |
|
|
1263 | |
|
|
1264 | =head3 Explanation of the columns |
|
|
1265 | |
|
|
1266 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1267 | each server has a read and write socket end). |
|
|
1268 | |
|
|
1269 | I<create> is the time it takes to create a socketpair (which is |
|
|
1270 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1271 | |
|
|
1272 | I<request>, the most important value, is the time it takes to handle a |
|
|
1273 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1274 | it to another server. This includes deleting the old timeout and creating |
|
|
1275 | a new one that moves the timeout into the future. |
|
|
1276 | |
|
|
1277 | =head3 Results |
|
|
1278 | |
|
|
1279 | name sockets create request |
|
|
1280 | EV 20000 69.01 11.16 |
|
|
1281 | Perl 20000 73.32 35.87 |
|
|
1282 | Event 20000 212.62 257.32 |
|
|
1283 | Glib 20000 651.16 1896.30 |
|
|
1284 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1285 | |
|
|
1286 | =head3 Discussion |
|
|
1287 | |
|
|
1288 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1289 | particular event loop. |
|
|
1290 | |
|
|
1291 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1292 | is relatively high, though. |
|
|
1293 | |
|
|
1294 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1295 | loops Event and Glib. |
|
|
1296 | |
|
|
1297 | Event suffers from high setup time as well (look at its code and you will |
|
|
1298 | understand why). Callback invocation also has a high overhead compared to |
|
|
1299 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1300 | uses select or poll in basically all documented configurations. |
|
|
1301 | |
|
|
1302 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1303 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1304 | |
|
|
1305 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1306 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1307 | it uses a C-based event loop in this case. |
|
|
1308 | |
|
|
1309 | =head3 Summary |
|
|
1310 | |
|
|
1311 | =over 4 |
|
|
1312 | |
|
|
1313 | =item * The pure perl implementation performs extremely well. |
|
|
1314 | |
|
|
1315 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1316 | |
|
|
1317 | =back |
|
|
1318 | |
|
|
1319 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1320 | |
|
|
1321 | While event loops should scale (and select-based ones do not...) even to |
|
|
1322 | large servers, most programs we (or I :) actually write have only a few |
|
|
1323 | I/O watchers. |
|
|
1324 | |
|
|
1325 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1326 | case, but it uses only eight "servers", of which three are active at any |
|
|
1327 | one time. This should reflect performance for a small server relatively |
|
|
1328 | well. |
|
|
1329 | |
|
|
1330 | The columns are identical to the previous table. |
|
|
1331 | |
|
|
1332 | =head3 Results |
|
|
1333 | |
|
|
1334 | name sockets create request |
|
|
1335 | EV 16 20.00 6.54 |
|
|
1336 | Perl 16 25.75 12.62 |
|
|
1337 | Event 16 81.27 35.86 |
|
|
1338 | Glib 16 32.63 15.48 |
|
|
1339 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1340 | |
|
|
1341 | =head3 Discussion |
|
|
1342 | |
|
|
1343 | The benchmark tries to test the performance of a typical small |
|
|
1344 | server. While knowing how various event loops perform is interesting, keep |
|
|
1345 | in mind that their overhead in this case is usually not as important, due |
|
|
1346 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1347 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1348 | them). |
|
|
1349 | |
|
|
1350 | EV is again fastest. |
|
|
1351 | |
|
|
1352 | Perl again comes second. It is noticably faster than the C-based event |
|
|
1353 | loops Event and Glib, although the difference is too small to really |
|
|
1354 | matter. |
|
|
1355 | |
|
|
1356 | POE also performs much better in this case, but is is still far behind the |
|
|
1357 | others. |
|
|
1358 | |
|
|
1359 | =head3 Summary |
|
|
1360 | |
|
|
1361 | =over 4 |
|
|
1362 | |
|
|
1363 | =item * C-based event loops perform very well with small number of |
|
|
1364 | watchers, as the management overhead dominates. |
|
|
1365 | |
|
|
1366 | =back |
|
|
1367 | |
|
|
1368 | |
|
|
1369 | =head1 FORK |
|
|
1370 | |
|
|
1371 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1372 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1373 | calls. Only L<EV> is fully fork-aware. |
|
|
1374 | |
|
|
1375 | If you have to fork, you must either do so I<before> creating your first |
|
|
1376 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1377 | |
|
|
1378 | |
|
|
1379 | =head1 SECURITY CONSIDERATIONS |
|
|
1380 | |
|
|
1381 | AnyEvent can be forced to load any event model via |
|
|
1382 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1383 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1384 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1385 | will not be active when the program uses a different event model than |
|
|
1386 | specified in the variable. |
|
|
1387 | |
|
|
1388 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1389 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1390 | |
|
|
1391 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1392 | |
|
|
1393 | use AnyEvent; |
|
|
1394 | |
|
|
1395 | |
669 | =head1 SEE ALSO |
1396 | =head1 SEE ALSO |
670 | |
1397 | |
671 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
1398 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
|
|
1399 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
|
|
1400 | L<Event::Lib>, L<Qt>, L<POE>. |
672 | |
1401 | |
|
|
1402 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
673 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
1403 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
|
|
1404 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
|
|
1405 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
674 | |
1406 | |
675 | Nontrivial usage example: L<Net::FCP>. |
1407 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
676 | |
1408 | |
677 | =head1 |
1409 | |
|
|
1410 | =head1 AUTHOR |
|
|
1411 | |
|
|
1412 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1413 | http://home.schmorp.de/ |
678 | |
1414 | |
679 | =cut |
1415 | =cut |
680 | |
1416 | |
681 | 1 |
1417 | 1 |
682 | |
1418 | |