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 |
22 | |
22 | |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
24 | |
24 | |
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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 | |
63 | Of course, if you want lots of policy (this can arguably be somewhat |
67 | Of course, if you want lots of policy (this can arguably be somewhat |
64 | useful) and you want to force your users to use the one and only event |
68 | useful) and you want to force your users to use the one and only event |
65 | model, you should I<not> use this module. |
69 | model, you should I<not> use this module. |
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70 | L<AnyEvent> provides an identical interface to multiple event loops. This |
74 | L<AnyEvent> provides an identical interface to multiple event loops. This |
71 | allows module authors to utilise an event loop without forcing module |
75 | allows module authors to utilise an event loop without forcing module |
72 | users to use the same event loop (as only a single event loop can coexist |
76 | users to use the same event loop (as only a single event loop can coexist |
73 | peacefully at any one time). |
77 | peacefully at any one time). |
74 | |
78 | |
75 | The interface itself is vaguely similar but not identical to the Event |
79 | The interface itself is vaguely similar, but not identical to the L<Event> |
76 | module. |
80 | module. |
77 | |
81 | |
78 | On the first call of any method, the module tries to detect the currently |
82 | During the first call of any watcher-creation method, the module tries |
79 | loaded event loop by probing wether any of the following modules is |
83 | to detect the currently loaded event loop by probing whether one of the |
80 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
84 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
81 | used. If none is found, the module tries to load these modules in the |
85 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
82 | order given. The first one that could be successfully loaded will be |
86 | L<POE>. The first one found is used. If none are found, the module tries |
83 | used. If still none could be found, AnyEvent will fall back to a pure-perl |
87 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
84 | event loop, which is also not very efficient. |
88 | adaptor should always succeed) in the order given. The first one that can |
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89 | be successfully loaded will be used. If, after this, still none could be |
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90 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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91 | very efficient, but should work everywhere. |
85 | |
92 | |
86 | Because AnyEvent first checks for modules that are already loaded, loading |
93 | Because AnyEvent first checks for modules that are already loaded, loading |
87 | an Event model explicitly before first using AnyEvent will likely make |
94 | an event model explicitly before first using AnyEvent will likely make |
88 | that model the default. For example: |
95 | that model the default. For example: |
89 | |
96 | |
90 | use Tk; |
97 | use Tk; |
91 | use AnyEvent; |
98 | use AnyEvent; |
92 | |
99 | |
93 | # .. AnyEvent will likely default to Tk |
100 | # .. AnyEvent will likely default to Tk |
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101 | |
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102 | The I<likely> means that, if any module loads another event model and |
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103 | starts using it, all bets are off. Maybe you should tell their authors to |
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104 | use AnyEvent so their modules work together with others seamlessly... |
94 | |
105 | |
95 | The pure-perl implementation of AnyEvent is called |
106 | The pure-perl implementation of AnyEvent is called |
96 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
107 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
97 | explicitly. |
108 | explicitly. |
98 | |
109 | |
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101 | AnyEvent has the central concept of a I<watcher>, which is an object that |
112 | AnyEvent has the central concept of a I<watcher>, which is an object that |
102 | stores relevant data for each kind of event you are waiting for, such as |
113 | stores relevant data for each kind of event you are waiting for, such as |
103 | the callback to call, the filehandle to watch, etc. |
114 | the callback to call, the filehandle to watch, etc. |
104 | |
115 | |
105 | These watchers are normal Perl objects with normal Perl lifetime. After |
116 | These watchers are normal Perl objects with normal Perl lifetime. After |
106 | creating a watcher it will immediately "watch" for events and invoke |
117 | creating a watcher it will immediately "watch" for events and invoke the |
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118 | callback when the event occurs (of course, only when the event model |
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119 | is in control). |
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120 | |
107 | the callback. To disable the watcher you have to destroy it (e.g. by |
121 | To disable the watcher you have to destroy it (e.g. by setting the |
108 | setting the variable that stores it to C<undef> or otherwise deleting all |
122 | variable you store it in to C<undef> or otherwise deleting all references |
109 | references to it). |
123 | to it). |
110 | |
124 | |
111 | All watchers are created by calling a method on the C<AnyEvent> class. |
125 | All watchers are created by calling a method on the C<AnyEvent> class. |
112 | |
126 | |
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127 | Many watchers either are used with "recursion" (repeating timers for |
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128 | example), or need to refer to their watcher object in other ways. |
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129 | |
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130 | An any way to achieve that is this pattern: |
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131 | |
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132 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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133 | # you can use $w here, for example to undef it |
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134 | undef $w; |
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135 | }); |
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136 | |
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137 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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138 | my variables are only visible after the statement in which they are |
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139 | declared. |
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140 | |
113 | =head2 IO WATCHERS |
141 | =head2 I/O WATCHERS |
114 | |
142 | |
115 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
143 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
116 | the following mandatory arguments: |
144 | with the following mandatory key-value pairs as arguments: |
117 | |
145 | |
118 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
146 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for |
119 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
147 | events. C<poll> must be a string that is either C<r> or C<w>, which |
120 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback |
148 | creates a watcher waiting for "r"eadable or "w"ritable events, |
121 | to invoke everytime the filehandle becomes ready. |
149 | respectively. C<cb> is the callback to invoke each time the file handle |
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150 | becomes ready. |
122 | |
151 | |
123 | Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
152 | The I/O watcher might use the underlying file descriptor or a copy of it. |
124 | a socket you can have one r + one w, not any more (limitation comes from |
153 | You must not close a file handle as long as any watcher is active on the |
125 | Tk - if you are sure you are not using Tk this limitation is gone). |
154 | underlying file descriptor. |
126 | |
155 | |
127 | Filehandles will be kept alive, so as long as the watcher exists, the |
156 | Some event loops issue spurious readyness notifications, so you should |
128 | filehandle exists, too. |
157 | always use non-blocking calls when reading/writing from/to your file |
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158 | handles. |
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159 | |
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160 | Although the callback might get passed parameters, their value and |
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161 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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162 | callbacks cannot use arguments passed to I/O watcher callbacks. |
129 | |
163 | |
130 | Example: |
164 | Example: |
131 | |
165 | |
132 | # wait for readability of STDIN, then read a line and disable the watcher |
166 | # wait for readability of STDIN, then read a line and disable the watcher |
133 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
167 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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139 | =head2 TIME WATCHERS |
173 | =head2 TIME WATCHERS |
140 | |
174 | |
141 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
175 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
142 | method with the following mandatory arguments: |
176 | method with the following mandatory arguments: |
143 | |
177 | |
144 | C<after> after how many seconds (fractions are supported) should the timer |
178 | C<after> specifies after how many seconds (fractional values are |
145 | activate. C<cb> the callback to invoke. |
179 | supported) should the timer activate. C<cb> the callback to invoke in that |
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180 | case. |
146 | |
181 | |
147 | The timer callback will be invoked at most once: if you want a repeating |
182 | The timer callback will be invoked at most once: if you want a repeating |
148 | timer you have to create a new watcher (this is a limitation by both Tk |
183 | timer you have to create a new watcher (this is a limitation by both Tk |
149 | and Glib). |
184 | and Glib). |
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185 | |
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186 | Although the callback might get passed parameters, their value and |
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187 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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188 | callbacks cannot use arguments passed to time watcher callbacks. |
150 | |
189 | |
151 | Example: |
190 | Example: |
152 | |
191 | |
153 | # fire an event after 7.7 seconds |
192 | # fire an event after 7.7 seconds |
154 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
193 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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156 | }); |
195 | }); |
157 | |
196 | |
158 | # to cancel the timer: |
197 | # to cancel the timer: |
159 | undef $w; |
198 | undef $w; |
160 | |
199 | |
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200 | Example 2: |
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201 | |
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202 | # fire an event after 0.5 seconds, then roughly every second |
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203 | my $w; |
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204 | |
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205 | my $cb = sub { |
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206 | # cancel the old timer while creating a new one |
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207 | $w = AnyEvent->timer (after => 1, cb => $cb); |
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208 | }; |
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209 | |
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210 | # start the "loop" by creating the first watcher |
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211 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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212 | |
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213 | =head3 TIMING ISSUES |
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214 | |
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215 | There are two ways to handle timers: based on real time (relative, "fire |
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216 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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217 | o'clock"). |
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218 | |
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219 | While most event loops expect timers to specified in a relative way, they |
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220 | use absolute time internally. This makes a difference when your clock |
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221 | "jumps", for example, when ntp decides to set your clock backwards from |
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222 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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223 | fire "after" a second might actually take six years to finally fire. |
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224 | |
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225 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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226 | about these issues is L<EV>, which offers both relative (ev_timer, based |
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227 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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228 | timers. |
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229 | |
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230 | AnyEvent always prefers relative timers, if available, matching the |
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231 | AnyEvent API. |
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232 | |
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233 | =head2 SIGNAL WATCHERS |
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234 | |
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235 | You can watch for signals using a signal watcher, C<signal> is the signal |
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236 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
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237 | be invoked whenever a signal occurs. |
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238 | |
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239 | Multiple signal occurances can be clumped together into one callback |
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240 | invocation, and callback invocation will be synchronous. synchronous means |
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241 | that it might take a while until the signal gets handled by the process, |
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242 | but it is guarenteed not to interrupt any other callbacks. |
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243 | |
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244 | The main advantage of using these watchers is that you can share a signal |
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245 | between multiple watchers. |
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246 | |
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247 | This watcher might use C<%SIG>, so programs overwriting those signals |
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248 | directly will likely not work correctly. |
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249 | |
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250 | Example: exit on SIGINT |
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251 | |
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252 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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253 | |
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254 | =head2 CHILD PROCESS WATCHERS |
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255 | |
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256 | You can also watch on a child process exit and catch its exit status. |
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257 | |
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258 | The child process is specified by the C<pid> argument (if set to C<0>, it |
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259 | watches for any child process exit). The watcher will trigger as often |
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260 | as status change for the child are received. This works by installing a |
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261 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
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262 | and exit status (as returned by waitpid). |
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263 | |
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264 | There is a slight catch to child watchers, however: you usually start them |
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265 | I<after> the child process was created, and this means the process could |
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266 | have exited already (and no SIGCHLD will be sent anymore). |
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267 | |
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268 | Not all event models handle this correctly (POE doesn't), but even for |
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269 | event models that I<do> handle this correctly, they usually need to be |
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270 | loaded before the process exits (i.e. before you fork in the first place). |
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271 | |
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272 | This means you cannot create a child watcher as the very first thing in an |
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273 | AnyEvent program, you I<have> to create at least one watcher before you |
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274 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
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275 | |
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276 | Example: fork a process and wait for it |
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277 | |
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278 | my $done = AnyEvent->condvar; |
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279 | |
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280 | AnyEvent::detect; # force event module to be initialised |
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281 | |
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282 | my $pid = fork or exit 5; |
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283 | |
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284 | my $w = AnyEvent->child ( |
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285 | pid => $pid, |
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286 | cb => sub { |
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287 | my ($pid, $status) = @_; |
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288 | warn "pid $pid exited with status $status"; |
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289 | $done->broadcast; |
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290 | }, |
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291 | ); |
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292 | |
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293 | # do something else, then wait for process exit |
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294 | $done->wait; |
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295 | |
161 | =head2 CONDITION WATCHERS |
296 | =head2 CONDITION VARIABLES |
162 | |
297 | |
163 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
298 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
164 | method without any arguments. |
299 | method without any arguments. |
165 | |
300 | |
166 | A condition watcher watches for a condition - precisely that the C<< |
301 | A condition variable waits for a condition - precisely that the C<< |
167 | ->broadcast >> method has been called. |
302 | ->broadcast >> method has been called. |
168 | |
303 | |
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304 | They are very useful to signal that a condition has been fulfilled, for |
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305 | example, if you write a module that does asynchronous http requests, |
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306 | then a condition variable would be the ideal candidate to signal the |
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307 | availability of results. |
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308 | |
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309 | You can also use condition variables to block your main program until |
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310 | an event occurs - for example, you could C<< ->wait >> in your main |
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311 | program until the user clicks the Quit button in your app, which would C<< |
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312 | ->broadcast >> the "quit" event. |
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313 | |
169 | Note that condition watchers recurse into the event loop - if you have |
314 | Note that condition variables recurse into the event loop - if you have |
170 | two watchers that call C<< ->wait >> in a round-robbin fashion, you |
315 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
171 | lose. Therefore, condition watchers are good to export to your caller, but |
316 | lose. Therefore, condition variables are good to export to your caller, but |
172 | you should avoid making a blocking wait, at least in callbacks, as this |
317 | you should avoid making a blocking wait yourself, at least in callbacks, |
173 | usually asks for trouble. |
318 | as this asks for trouble. |
174 | |
319 | |
175 | The watcher has only two methods: |
320 | This object has two methods: |
176 | |
321 | |
177 | =over 4 |
322 | =over 4 |
178 | |
323 | |
179 | =item $cv->wait |
324 | =item $cv->wait |
180 | |
325 | |
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183 | |
328 | |
184 | You can only wait once on a condition - additional calls will return |
329 | You can only wait once on a condition - additional calls will return |
185 | immediately. |
330 | immediately. |
186 | |
331 | |
187 | Not all event models support a blocking wait - some die in that case |
332 | Not all event models support a blocking wait - some die in that case |
188 | (programs might want to do that so they stay interactive), so I<if you |
333 | (programs might want to do that to stay interactive), so I<if you are |
189 | are using this from a module, never require a blocking wait>, but let the |
334 | using this from a module, never require a blocking wait>, but let the |
190 | caller decide wether the call will block or not (for example, by coupling |
335 | caller decide whether the call will block or not (for example, by coupling |
191 | condition variables with some kind of request results and supporting |
336 | condition variables with some kind of request results and supporting |
192 | callbacks so the caller knows that getting the result will not block, |
337 | callbacks so the caller knows that getting the result will not block, |
193 | while still suppporting blocking waits if the caller so desires). |
338 | while still suppporting blocking waits if the caller so desires). |
194 | |
339 | |
195 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
340 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
196 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
341 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
197 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
342 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
198 | can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event> |
343 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
199 | explicitly support concurrent C<< ->wait >>'s from different coroutines, |
344 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
200 | however). |
345 | from different coroutines, however). |
201 | |
346 | |
202 | =item $cv->broadcast |
347 | =item $cv->broadcast |
203 | |
348 | |
204 | Flag the condition as ready - a running C<< ->wait >> and all further |
349 | Flag the condition as ready - a running C<< ->wait >> and all further |
205 | calls to C<wait> will return after this method has been called. If nobody |
350 | calls to C<wait> will (eventually) return after this method has been |
206 | is waiting the broadcast will be remembered.. |
351 | called. If nobody is waiting the broadcast will be remembered.. |
|
|
352 | |
|
|
353 | =back |
207 | |
354 | |
208 | Example: |
355 | Example: |
209 | |
356 | |
210 | # wait till the result is ready |
357 | # wait till the result is ready |
211 | my $result_ready = AnyEvent->condvar; |
358 | my $result_ready = AnyEvent->condvar; |
212 | |
359 | |
213 | # do something such as adding a timer |
360 | # do something such as adding a timer |
214 | # or socket watcher the calls $result_ready->broadcast |
361 | # or socket watcher the calls $result_ready->broadcast |
215 | # when the "result" is ready. |
362 | # when the "result" is ready. |
|
|
363 | # in this case, we simply use a timer: |
|
|
364 | my $w = AnyEvent->timer ( |
|
|
365 | after => 1, |
|
|
366 | cb => sub { $result_ready->broadcast }, |
|
|
367 | ); |
216 | |
368 | |
|
|
369 | # this "blocks" (while handling events) till the watcher |
|
|
370 | # calls broadcast |
217 | $result_ready->wait; |
371 | $result_ready->wait; |
218 | |
372 | |
219 | =back |
373 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
220 | |
|
|
221 | =head2 SIGNAL WATCHERS |
|
|
222 | |
|
|
223 | You can listen for signals using a signal watcher, C<signal> is the signal |
|
|
224 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
|
|
225 | together into one callback invocation, and callback invocation might or |
|
|
226 | might not be asynchronous. |
|
|
227 | |
|
|
228 | These watchers might use C<%SIG>, so programs overwriting those signals |
|
|
229 | directly will likely not work correctly. |
|
|
230 | |
|
|
231 | Example: exit on SIGINT |
|
|
232 | |
|
|
233 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
234 | |
|
|
235 | =head2 CHILD PROCESS WATCHERS |
|
|
236 | |
|
|
237 | You can also listen for the status of a child process specified by the |
|
|
238 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
|
|
239 | trigger as often as status change for the child are received. This works |
|
|
240 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
|
|
241 | the pid and exit status (as returned by waitpid). |
|
|
242 | |
|
|
243 | Example: wait for pid 1333 |
|
|
244 | |
|
|
245 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
|
|
246 | |
|
|
247 | =head1 GLOBALS |
|
|
248 | |
374 | |
249 | =over 4 |
375 | =over 4 |
250 | |
376 | |
251 | =item $AnyEvent::MODEL |
377 | =item $AnyEvent::MODEL |
252 | |
378 | |
… | |
… | |
257 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
383 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
258 | |
384 | |
259 | The known classes so far are: |
385 | The known classes so far are: |
260 | |
386 | |
261 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
387 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
262 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
|
|
263 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
388 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
|
|
389 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
264 | AnyEvent::Impl::Event based on Event, also second best choice :) |
390 | AnyEvent::Impl::Event based on Event, second best choice. |
265 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
391 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
392 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
266 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
393 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
267 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
394 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
395 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
396 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
397 | |
|
|
398 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
399 | watching file handles. However, you can use WxWidgets through the |
|
|
400 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
401 | second, which was considered to be too horrible to even consider for |
|
|
402 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
403 | it's adaptor. |
|
|
404 | |
|
|
405 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
406 | autodetecting them. |
268 | |
407 | |
269 | =item AnyEvent::detect |
408 | =item AnyEvent::detect |
270 | |
409 | |
271 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
410 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
272 | necessary. You should only call this function right before you would have |
411 | if necessary. You should only call this function right before you would |
273 | created an AnyEvent watcher anyway, that is, very late at runtime. |
412 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
413 | runtime. |
274 | |
414 | |
275 | =back |
415 | =back |
276 | |
416 | |
277 | =head1 WHAT TO DO IN A MODULE |
417 | =head1 WHAT TO DO IN A MODULE |
278 | |
418 | |
279 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
419 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
280 | freely, but you should not load a specific event module or rely on it. |
420 | freely, but you should not load a specific event module or rely on it. |
281 | |
421 | |
282 | Be careful when you create watchers in the module body - Anyevent will |
422 | Be careful when you create watchers in the module body - AnyEvent will |
283 | decide which event module to use as soon as the first method is called, so |
423 | decide which event module to use as soon as the first method is called, so |
284 | by calling AnyEvent in your module body you force the user of your module |
424 | by calling AnyEvent in your module body you force the user of your module |
285 | to load the event module first. |
425 | to load the event module first. |
286 | |
426 | |
|
|
427 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
|
|
428 | the C<< ->broadcast >> method has been called on it already. This is |
|
|
429 | because it will stall the whole program, and the whole point of using |
|
|
430 | events is to stay interactive. |
|
|
431 | |
|
|
432 | It is fine, however, to call C<< ->wait >> when the user of your module |
|
|
433 | requests it (i.e. if you create a http request object ad have a method |
|
|
434 | called C<results> that returns the results, it should call C<< ->wait >> |
|
|
435 | freely, as the user of your module knows what she is doing. always). |
|
|
436 | |
287 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
437 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
288 | |
438 | |
289 | There will always be a single main program - the only place that should |
439 | There will always be a single main program - the only place that should |
290 | dictate which event model to use. |
440 | dictate which event model to use. |
291 | |
441 | |
292 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
442 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
293 | do anything special and let AnyEvent decide which implementation to chose. |
443 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
444 | decide which implementation to chose if some module relies on it. |
294 | |
445 | |
295 | If the main program relies on a specific event model (for example, in Gtk2 |
446 | If the main program relies on a specific event model. For example, in |
296 | programs you have to rely on either Glib or Glib::Event), you should load |
447 | Gtk2 programs you have to rely on the Glib module. You should load the |
297 | it before loading AnyEvent or any module that uses it, generally, as early |
448 | event module before loading AnyEvent or any module that uses it: generally |
298 | as possible. The reason is that modules might create watchers when they |
449 | speaking, you should load it as early as possible. The reason is that |
299 | are loaded, and AnyEvent will decide on the event model to use as soon as |
450 | modules might create watchers when they are loaded, and AnyEvent will |
300 | it creates watchers, and it might chose the wrong one unless you load the |
451 | decide on the event model to use as soon as it creates watchers, and it |
301 | correct one yourself. |
452 | might chose the wrong one unless you load the correct one yourself. |
302 | |
453 | |
303 | You can chose to use a rather inefficient pure-perl implementation by |
454 | You can chose to use a rather inefficient pure-perl implementation by |
304 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
455 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
305 | generally better. |
456 | behaviour everywhere, but letting AnyEvent chose is generally better. |
306 | |
457 | |
307 | =cut |
458 | =cut |
308 | |
459 | |
309 | package AnyEvent; |
460 | package AnyEvent; |
310 | |
461 | |
311 | no warnings; |
462 | no warnings; |
312 | use strict; |
463 | use strict; |
313 | |
464 | |
314 | use Carp; |
465 | use Carp; |
315 | |
466 | |
316 | our $VERSION = '3.0'; |
467 | our $VERSION = '3.3'; |
317 | our $MODEL; |
468 | our $MODEL; |
318 | |
469 | |
319 | our $AUTOLOAD; |
470 | our $AUTOLOAD; |
320 | our @ISA; |
471 | our @ISA; |
321 | |
472 | |
… | |
… | |
323 | |
474 | |
324 | our @REGISTRY; |
475 | our @REGISTRY; |
325 | |
476 | |
326 | my @models = ( |
477 | my @models = ( |
327 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
478 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
479 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
328 | [EV:: => AnyEvent::Impl::EV::], |
480 | [EV:: => AnyEvent::Impl::EV::], |
329 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
330 | [Event:: => AnyEvent::Impl::Event::], |
481 | [Event:: => AnyEvent::Impl::Event::], |
331 | [Glib:: => AnyEvent::Impl::Glib::], |
482 | [Glib:: => AnyEvent::Impl::Glib::], |
332 | [Tk:: => AnyEvent::Impl::Tk::], |
483 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
484 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
485 | [Prima:: => AnyEvent::Impl::POE::], |
333 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
486 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
487 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
|
|
488 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
489 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
490 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
334 | ); |
491 | ); |
335 | |
492 | |
336 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
493 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
337 | |
494 | |
338 | sub detect() { |
495 | sub detect() { |
339 | unless ($MODEL) { |
496 | unless ($MODEL) { |
340 | no strict 'refs'; |
497 | no strict 'refs'; |
341 | |
498 | |
|
|
499 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
500 | my $model = "AnyEvent::Impl::$1"; |
|
|
501 | if (eval "require $model") { |
|
|
502 | $MODEL = $model; |
|
|
503 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
504 | } else { |
|
|
505 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
506 | } |
|
|
507 | } |
|
|
508 | |
342 | # check for already loaded models |
509 | # check for already loaded models |
|
|
510 | unless ($MODEL) { |
343 | for (@REGISTRY, @models) { |
511 | for (@REGISTRY, @models) { |
344 | my ($package, $model) = @$_; |
512 | my ($package, $model) = @$_; |
345 | if (${"$package\::VERSION"} > 0) { |
513 | if (${"$package\::VERSION"} > 0) { |
346 | if (eval "require $model") { |
514 | if (eval "require $model") { |
347 | $MODEL = $model; |
515 | $MODEL = $model; |
348 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
516 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
349 | last; |
517 | last; |
|
|
518 | } |
350 | } |
519 | } |
351 | } |
520 | } |
352 | } |
|
|
353 | |
521 | |
354 | unless ($MODEL) { |
522 | unless ($MODEL) { |
355 | # try to load a model |
523 | # try to load a model |
356 | |
524 | |
357 | for (@REGISTRY, @models) { |
525 | for (@REGISTRY, @models) { |
358 | my ($package, $model) = @$_; |
526 | my ($package, $model) = @$_; |
359 | if (eval "require $package" |
527 | if (eval "require $package" |
360 | and ${"$package\::VERSION"} > 0 |
528 | and ${"$package\::VERSION"} > 0 |
361 | and eval "require $model") { |
529 | and eval "require $model") { |
362 | $MODEL = $model; |
530 | $MODEL = $model; |
363 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
531 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
364 | last; |
532 | last; |
|
|
533 | } |
365 | } |
534 | } |
|
|
535 | |
|
|
536 | $MODEL |
|
|
537 | 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."; |
366 | } |
538 | } |
367 | |
|
|
368 | $MODEL |
|
|
369 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event), Glib or Tk."; |
|
|
370 | } |
539 | } |
371 | |
540 | |
372 | unshift @ISA, $MODEL; |
541 | unshift @ISA, $MODEL; |
373 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
542 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
374 | } |
543 | } |
… | |
… | |
485 | undef $CHLD_W unless keys %PID_CB; |
654 | undef $CHLD_W unless keys %PID_CB; |
486 | } |
655 | } |
487 | |
656 | |
488 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
657 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
489 | |
658 | |
|
|
659 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
660 | a module. This section is only of use to event loop authors who want to |
|
|
661 | provide AnyEvent compatibility. |
|
|
662 | |
490 | If you need to support another event library which isn't directly |
663 | If you need to support another event library which isn't directly |
491 | supported by AnyEvent, you can supply your own interface to it by |
664 | supported by AnyEvent, you can supply your own interface to it by |
492 | pushing, before the first watcher gets created, the package name of |
665 | pushing, before the first watcher gets created, the package name of |
493 | the event module and the package name of the interface to use onto |
666 | the event module and the package name of the interface to use onto |
494 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
667 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
495 | AnyEvent. |
668 | AnyEvent, so it is reasonably cheap. |
496 | |
669 | |
497 | Example: |
670 | Example: |
498 | |
671 | |
499 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
672 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
500 | |
673 | |
501 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
674 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
502 | package/class when it finds the C<urxvt> package/module is loaded. When |
675 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
676 | |
503 | AnyEvent is loaded and asked to find a suitable event model, it will |
677 | When AnyEvent is loaded and asked to find a suitable event model, it |
504 | first check for the presence of urxvt. |
678 | will first check for the presence of urxvt by trying to C<use> the |
|
|
679 | C<urxvt::anyevent> module. |
505 | |
680 | |
506 | The class should provide implementations for all watcher types (see |
681 | The class should provide implementations for all watcher types. See |
507 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
682 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
508 | (Source code) and so on for actual examples, use C<perldoc -m |
683 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
509 | AnyEvent::Impl::Glib> to see the sources). |
684 | see the sources. |
510 | |
685 | |
|
|
686 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
687 | provide suitable (hopefully) replacements. |
|
|
688 | |
511 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
689 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
512 | uses the above line as-is. An interface isn't included in AnyEvent |
690 | terminal emulator uses the above line as-is. An interface isn't included |
513 | because it doesn't make sense outside the embedded interpreter inside |
691 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
514 | I<rxvt-unicode>, and it is updated and maintained as part of the |
692 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
515 | I<rxvt-unicode> distribution. |
693 | I<rxvt-unicode> distribution. |
516 | |
694 | |
517 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
695 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
518 | condition variables: code blocking while waiting for a condition will |
696 | condition variables: code blocking while waiting for a condition will |
519 | C<die>. This still works with most modules/usages, and blocking calls must |
697 | C<die>. This still works with most modules/usages, and blocking calls must |
520 | not be in an interactive application, so it makes sense. |
698 | not be done in an interactive application, so it makes sense. |
521 | |
699 | |
522 | =head1 ENVIRONMENT VARIABLES |
700 | =head1 ENVIRONMENT VARIABLES |
523 | |
701 | |
524 | The following environment variables are used by this module: |
702 | The following environment variables are used by this module: |
525 | |
703 | |
526 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
704 | =over 4 |
527 | model gets used. |
|
|
528 | |
705 | |
|
|
706 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
707 | |
|
|
708 | By default, AnyEvent will be completely silent except in fatal |
|
|
709 | conditions. You can set this environment variable to make AnyEvent more |
|
|
710 | talkative. |
|
|
711 | |
|
|
712 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
713 | conditions, such as not being able to load the event model specified by |
|
|
714 | C<PERL_ANYEVENT_MODEL>. |
|
|
715 | |
|
|
716 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
717 | model it chooses. |
|
|
718 | |
|
|
719 | =item C<PERL_ANYEVENT_MODEL> |
|
|
720 | |
|
|
721 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
722 | autodetection and -probing kicks in. It must be a string consisting |
|
|
723 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
724 | and the resulting module name is loaded and if the load was successful, |
|
|
725 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
726 | autodetection and -probing. |
|
|
727 | |
|
|
728 | This functionality might change in future versions. |
|
|
729 | |
|
|
730 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
731 | could start your program like this: |
|
|
732 | |
|
|
733 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
734 | |
|
|
735 | =back |
|
|
736 | |
529 | =head1 EXAMPLE |
737 | =head1 EXAMPLE PROGRAM |
530 | |
738 | |
531 | The following program uses an io watcher to read data from stdin, a timer |
739 | The following program uses an I/O watcher to read data from STDIN, a timer |
532 | to display a message once per second, and a condvar to exit the program |
740 | to display a message once per second, and a condition variable to quit the |
533 | when the user enters quit: |
741 | program when the user enters quit: |
534 | |
742 | |
535 | use AnyEvent; |
743 | use AnyEvent; |
536 | |
744 | |
537 | my $cv = AnyEvent->condvar; |
745 | my $cv = AnyEvent->condvar; |
538 | |
746 | |
539 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
747 | my $io_watcher = AnyEvent->io ( |
|
|
748 | fh => \*STDIN, |
|
|
749 | poll => 'r', |
|
|
750 | cb => sub { |
540 | warn "io event <$_[0]>\n"; # will always output <r> |
751 | warn "io event <$_[0]>\n"; # will always output <r> |
541 | chomp (my $input = <STDIN>); # read a line |
752 | chomp (my $input = <STDIN>); # read a line |
542 | warn "read: $input\n"; # output what has been read |
753 | warn "read: $input\n"; # output what has been read |
543 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
754 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
|
|
755 | }, |
544 | }); |
756 | ); |
545 | |
757 | |
546 | my $time_watcher; # can only be used once |
758 | my $time_watcher; # can only be used once |
547 | |
759 | |
548 | sub new_timer { |
760 | sub new_timer { |
549 | $timer = AnyEvent->timer (after => 1, cb => sub { |
761 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
631 | $txn->{finished}->wait; |
843 | $txn->{finished}->wait; |
632 | return $txn->{result}; |
844 | return $txn->{result}; |
633 | |
845 | |
634 | The actual code goes further and collects all errors (C<die>s, exceptions) |
846 | The actual code goes further and collects all errors (C<die>s, exceptions) |
635 | that occured during request processing. The C<result> method detects |
847 | that occured during request processing. The C<result> method detects |
636 | wether an exception as thrown (it is stored inside the $txn object) |
848 | whether an exception as thrown (it is stored inside the $txn object) |
637 | and just throws the exception, which means connection errors and other |
849 | and just throws the exception, which means connection errors and other |
638 | problems get reported tot he code that tries to use the result, not in a |
850 | problems get reported tot he code that tries to use the result, not in a |
639 | random callback. |
851 | random callback. |
640 | |
852 | |
641 | All of this enables the following usage styles: |
853 | All of this enables the following usage styles: |
… | |
… | |
676 | $quit->broadcast; |
888 | $quit->broadcast; |
677 | }); |
889 | }); |
678 | |
890 | |
679 | $quit->wait; |
891 | $quit->wait; |
680 | |
892 | |
|
|
893 | |
|
|
894 | =head1 BENCHMARK |
|
|
895 | |
|
|
896 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
897 | over the event loops themselves (and to give you an impression of the |
|
|
898 | speed of various event loops), here is a benchmark of various supported |
|
|
899 | event models natively and with anyevent. The benchmark creates a lot of |
|
|
900 | timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to |
|
|
901 | become writable, which it is), lets them fire exactly once and destroys |
|
|
902 | them again. |
|
|
903 | |
|
|
904 | Rewriting the benchmark to use many different sockets instead of using |
|
|
905 | the same filehandle for all I/O watchers results in a much longer runtime |
|
|
906 | (socket creation is expensive), but qualitatively the same figures, so it |
|
|
907 | was not used. |
|
|
908 | |
|
|
909 | =head2 Explanation of the columns |
|
|
910 | |
|
|
911 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
912 | different event models feature vastly different performances, each event |
|
|
913 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
914 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
915 | would probably take thousands of years if asked to process the same number |
|
|
916 | of watchers as EV in this benchmark. |
|
|
917 | |
|
|
918 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
919 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
920 | and Perl-based overheads. |
|
|
921 | |
|
|
922 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
923 | takes to create a single watcher. The callback is a closure shared between |
|
|
924 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
925 | and memory usage is not included in the figures. |
|
|
926 | |
|
|
927 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
928 | callback. The callback simply counts down a Perl variable and after it was |
|
|
929 | invoked "watcher" times, it would C<< ->broadcast >> a condvar once to |
|
|
930 | signal the end of this phase. |
|
|
931 | |
|
|
932 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
933 | watcher. |
|
|
934 | |
|
|
935 | =head2 Results |
|
|
936 | |
|
|
937 | name watchers bytes create invoke destroy comment |
|
|
938 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
939 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
940 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
941 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
942 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
943 | Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers |
|
|
944 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
945 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
946 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
947 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
948 | |
|
|
949 | =head2 Discussion |
|
|
950 | |
|
|
951 | The benchmark does I<not> measure scalability of the event loop very |
|
|
952 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
953 | can never compete with an event loop that uses epoll when the number of |
|
|
954 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
955 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
956 | boost. |
|
|
957 | |
|
|
958 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
959 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
960 | far less memory than any other event loop and is still faster than Event |
|
|
961 | natively. |
|
|
962 | |
|
|
963 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
964 | zero timeout and the use of a single fd hit optimisations in the perl |
|
|
965 | interpreter and the backend itself, and all watchers become ready at the |
|
|
966 | same time). Nevertheless this shows that it adds very little overhead in |
|
|
967 | itself. Like any select-based backend its performance becomes really bad |
|
|
968 | with lots of file descriptors (and few of them active), of course, but |
|
|
969 | this was not subject of this benchmark. |
|
|
970 | |
|
|
971 | The C<Event> module has a relatively high setup and callback invocation cost, |
|
|
972 | but overall scores on the third place. |
|
|
973 | |
|
|
974 | C<Glib>'s memory usage is quite a bit bit higher, but it features a |
|
|
975 | faster callback invocation and overall ends up in the same class as |
|
|
976 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
977 | watchers increases the processing time by more than a factor of four, |
|
|
978 | making it completely unusable when using larger numbers of watchers |
|
|
979 | (note that only a single file descriptor was used in the benchmark, so |
|
|
980 | inefficiencies of C<poll> do not account for this). |
|
|
981 | |
|
|
982 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
983 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
984 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
985 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
986 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
987 | hidden memory cost inside the kernel, though, that is not reflected in the |
|
|
988 | figures above). |
|
|
989 | |
|
|
990 | C<POE>, regardless of underlying event loop (wether using its pure perl |
|
|
991 | select-based backend or the Event module) shows abysmal performance and |
|
|
992 | memory usage: Watchers use almost 30 times as much memory as EV watchers, |
|
|
993 | and 10 times as much memory as both Event or EV via AnyEvent. Watcher |
|
|
994 | invocation is almost 900 times slower than with AnyEvent's pure perl |
|
|
995 | implementation. The design of the POE adaptor class in AnyEvent can not |
|
|
996 | really account for this, as session creation overhead is small compared |
|
|
997 | to execution of the state machine, which is coded pretty optimally within |
|
|
998 | L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow. |
|
|
999 | |
|
|
1000 | =head2 Summary |
|
|
1001 | |
|
|
1002 | Using EV through AnyEvent is faster than any other event loop, but most |
|
|
1003 | event loops have acceptable performance with or without AnyEvent. |
|
|
1004 | |
|
|
1005 | The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1006 | the actual event loop, only with extremely fast event loops such as the EV |
|
|
1007 | adds AnyEvent significant overhead. |
|
|
1008 | |
|
|
1009 | And you should simply avoid POE like the plague if you want performance or |
|
|
1010 | reasonable memory usage. |
|
|
1011 | |
|
|
1012 | |
|
|
1013 | =head1 FORK |
|
|
1014 | |
|
|
1015 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1016 | because they are so inefficient. Only L<EV> is fully fork-aware. |
|
|
1017 | |
|
|
1018 | If you have to fork, you must either do so I<before> creating your first |
|
|
1019 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1020 | |
|
|
1021 | |
|
|
1022 | =head1 SECURITY CONSIDERATIONS |
|
|
1023 | |
|
|
1024 | AnyEvent can be forced to load any event model via |
|
|
1025 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1026 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1027 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1028 | will not be active when the program uses a different event model than |
|
|
1029 | specified in the variable. |
|
|
1030 | |
|
|
1031 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1032 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1033 | |
|
|
1034 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1035 | |
|
|
1036 | use AnyEvent; |
|
|
1037 | |
|
|
1038 | |
681 | =head1 SEE ALSO |
1039 | =head1 SEE ALSO |
682 | |
1040 | |
683 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1041 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
684 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
1042 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
|
|
1043 | L<Event::Lib>, L<Qt>, L<POE>. |
685 | |
1044 | |
686 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
1045 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
|
|
1046 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
|
|
1047 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
687 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
1048 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
688 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
|
|
689 | |
1049 | |
690 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
1050 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
691 | |
1051 | |
692 | =head1 |
1052 | |
|
|
1053 | =head1 AUTHOR |
|
|
1054 | |
|
|
1055 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1056 | http://home.schmorp.de/ |
693 | |
1057 | |
694 | =cut |
1058 | =cut |
695 | |
1059 | |
696 | 1 |
1060 | 1 |
697 | |
1061 | |