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 - various supported event loops |
6 | |
6 | |
7 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
8 | |
8 | |
9 | use AnyEvent; |
9 | use AnyEvent; |
10 | |
10 | |
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… | |
14 | |
14 | |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
16 | ... |
16 | ... |
17 | }); |
17 | }); |
18 | |
18 | |
19 | my $w = AnyEvent->condvar; # stores wether a condition was flagged |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
21 | $w->broadcast; # wake up current and all future wait's |
21 | $w->broadcast; # wake up current and all future wait's |
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22 | |
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23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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24 | |
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25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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26 | nowadays. So what is different about AnyEvent? |
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27 | |
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28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
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29 | policy> and AnyEvent is I<small and efficient>. |
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30 | |
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31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
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32 | interfaces to whatever event model the main program happens to use in a |
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33 | pragmatic way. For event models and certain classes of immortals alike, |
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34 | the statement "there can only be one" is a bitter reality: In general, |
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35 | only one event loop can be active at the same time in a process. AnyEvent |
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36 | helps hiding the differences between those event loops. |
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37 | |
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38 | The goal of AnyEvent is to offer module authors the ability to do event |
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39 | programming (waiting for I/O or timer events) without subscribing to a |
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40 | religion, a way of living, and most importantly: without forcing your |
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41 | module users into the same thing by forcing them to use the same event |
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42 | model you use. |
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43 | |
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44 | For modules like POE or IO::Async (which is a total misnomer as it is |
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45 | actually doing all I/O I<synchronously>...), using them in your module is |
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46 | like joining a cult: After you joined, you are dependent on them and you |
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47 | cannot use anything else, as it is simply incompatible to everything that |
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48 | isn't itself. What's worse, all the potential users of your module are |
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49 | I<also> forced to use the same event loop you use. |
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50 | |
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51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
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52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
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53 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if |
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54 | your module uses one of those, every user of your module has to use it, |
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55 | too. But if your module uses AnyEvent, it works transparently with all |
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56 | event models it supports (including stuff like POE and IO::Async, as long |
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57 | as those use one of the supported event loops. It is trivial to add new |
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58 | event loops to AnyEvent, too, so it is future-proof). |
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59 | |
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60 | In addition to being free of having to use I<the one and only true event |
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61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
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62 | modules, you get an enourmous amount of code and strict rules you have to |
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63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
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64 | offering the functionality that is necessary, in as thin as a wrapper as |
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65 | technically possible. |
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66 | |
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67 | Of course, if you want lots of policy (this can arguably be somewhat |
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68 | useful) and you want to force your users to use the one and only event |
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69 | model, you should I<not> use this module. |
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70 | |
22 | |
71 | |
23 | =head1 DESCRIPTION |
72 | =head1 DESCRIPTION |
24 | |
73 | |
25 | L<AnyEvent> provides an identical interface to multiple event loops. This |
74 | L<AnyEvent> provides an identical interface to multiple event loops. This |
26 | allows module authors to utilise an event loop without forcing module |
75 | allows module authors to utilise an event loop without forcing module |
27 | users to use the same event loop (as only a single event loop can coexist |
76 | users to use the same event loop (as only a single event loop can coexist |
28 | peacefully at any one time). |
77 | peacefully at any one time). |
29 | |
78 | |
30 | 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> |
31 | module. |
80 | module. |
32 | |
81 | |
33 | 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 |
34 | 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 |
35 | 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>, |
36 | used. If none is found, the module tries to load these modules in the |
85 | L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found, |
37 | order given. The first one that could be successfully loaded will be |
86 | the module tries to load these modules in the stated order. The first one |
38 | used. If still none could be found, AnyEvent will fall back to a pure-perl |
87 | that can be successfully loaded will be used. If, after this, still none |
39 | event loop, which is also not very efficient. |
88 | could be found, AnyEvent will fall back to a pure-perl event loop, which |
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89 | is not very efficient, but should work everywhere. |
40 | |
90 | |
41 | Because AnyEvent first checks for modules that are already loaded, loading |
91 | Because AnyEvent first checks for modules that are already loaded, loading |
42 | an Event model explicitly before first using AnyEvent will likely make |
92 | an event model explicitly before first using AnyEvent will likely make |
43 | that model the default. For example: |
93 | that model the default. For example: |
44 | |
94 | |
45 | use Tk; |
95 | use Tk; |
46 | use AnyEvent; |
96 | use AnyEvent; |
47 | |
97 | |
48 | # .. AnyEvent will likely default to Tk |
98 | # .. AnyEvent will likely default to Tk |
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99 | |
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100 | The I<likely> means that, if any module loads another event model and |
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101 | starts using it, all bets are off. Maybe you should tell their authors to |
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102 | use AnyEvent so their modules work together with others seamlessly... |
49 | |
103 | |
50 | The pure-perl implementation of AnyEvent is called |
104 | The pure-perl implementation of AnyEvent is called |
51 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
105 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
52 | explicitly. |
106 | explicitly. |
53 | |
107 | |
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56 | AnyEvent has the central concept of a I<watcher>, which is an object that |
110 | AnyEvent has the central concept of a I<watcher>, which is an object that |
57 | stores relevant data for each kind of event you are waiting for, such as |
111 | stores relevant data for each kind of event you are waiting for, such as |
58 | the callback to call, the filehandle to watch, etc. |
112 | the callback to call, the filehandle to watch, etc. |
59 | |
113 | |
60 | These watchers are normal Perl objects with normal Perl lifetime. After |
114 | These watchers are normal Perl objects with normal Perl lifetime. After |
61 | creating a watcher it will immediately "watch" for events and invoke |
115 | creating a watcher it will immediately "watch" for events and invoke the |
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116 | callback when the event occurs (of course, only when the event model |
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117 | is in control). |
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118 | |
62 | the callback. To disable the watcher you have to destroy it (e.g. by |
119 | To disable the watcher you have to destroy it (e.g. by setting the |
63 | setting the variable that stores it to C<undef> or otherwise deleting all |
120 | variable you store it in to C<undef> or otherwise deleting all references |
64 | references to it). |
121 | to it). |
65 | |
122 | |
66 | All watchers are created by calling a method on the C<AnyEvent> class. |
123 | All watchers are created by calling a method on the C<AnyEvent> class. |
67 | |
124 | |
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125 | Many watchers either are used with "recursion" (repeating timers for |
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126 | example), or need to refer to their watcher object in other ways. |
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127 | |
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128 | An any way to achieve that is this pattern: |
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129 | |
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130 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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131 | # you can use $w here, for example to undef it |
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132 | undef $w; |
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133 | }); |
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134 | |
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135 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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136 | my variables are only visible after the statement in which they are |
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137 | declared. |
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138 | |
68 | =head2 IO WATCHERS |
139 | =head2 IO WATCHERS |
69 | |
140 | |
70 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
141 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
71 | the following mandatory arguments: |
142 | with the following mandatory key-value pairs as arguments: |
72 | |
143 | |
73 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
144 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for |
74 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
145 | events. C<poll> must be a string that is either C<r> or C<w>, which |
75 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback |
146 | creates a watcher waiting for "r"eadable or "w"ritable events, |
76 | to invoke everytime the filehandle becomes ready. |
147 | respectively. C<cb> is the callback to invoke each time the file handle |
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148 | becomes ready. |
77 | |
149 | |
78 | Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
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79 | a socket you can have one r + one w, not any more (limitation comes from |
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80 | Tk - if you are sure you are not using Tk this limitation is gone). |
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81 | |
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82 | Filehandles will be kept alive, so as long as the watcher exists, the |
150 | File handles will be kept alive, so as long as the watcher exists, the |
83 | filehandle exists, too. |
151 | file handle exists, too. |
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152 | |
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153 | It is not allowed to close a file handle as long as any watcher is active |
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154 | on the underlying file descriptor. |
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155 | |
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156 | Some event loops issue spurious readyness notifications, so you should |
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157 | always use non-blocking calls when reading/writing from/to your file |
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158 | handles. |
84 | |
159 | |
85 | Example: |
160 | Example: |
86 | |
161 | |
87 | # wait for readability of STDIN, then read a line and disable the watcher |
162 | # wait for readability of STDIN, then read a line and disable the watcher |
88 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
163 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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94 | =head2 TIME WATCHERS |
169 | =head2 TIME WATCHERS |
95 | |
170 | |
96 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
171 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
97 | method with the following mandatory arguments: |
172 | method with the following mandatory arguments: |
98 | |
173 | |
99 | C<after> after how many seconds (fractions are supported) should the timer |
174 | C<after> specifies after how many seconds (fractional values are |
100 | activate. C<cb> the callback to invoke. |
175 | supported) should the timer activate. C<cb> the callback to invoke in that |
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176 | case. |
101 | |
177 | |
102 | The timer callback will be invoked at most once: if you want a repeating |
178 | The timer callback will be invoked at most once: if you want a repeating |
103 | timer you have to create a new watcher (this is a limitation by both Tk |
179 | timer you have to create a new watcher (this is a limitation by both Tk |
104 | and Glib). |
180 | and Glib). |
105 | |
181 | |
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111 | }); |
187 | }); |
112 | |
188 | |
113 | # to cancel the timer: |
189 | # to cancel the timer: |
114 | undef $w; |
190 | undef $w; |
115 | |
191 | |
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192 | Example 2: |
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193 | |
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194 | # fire an event after 0.5 seconds, then roughly every second |
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195 | my $w; |
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196 | |
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197 | my $cb = sub { |
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198 | # cancel the old timer while creating a new one |
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199 | $w = AnyEvent->timer (after => 1, cb => $cb); |
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200 | }; |
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201 | |
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202 | # start the "loop" by creating the first watcher |
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203 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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204 | |
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205 | =head3 TIMING ISSUES |
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206 | |
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207 | There are two ways to handle timers: based on real time (relative, "fire |
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208 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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209 | o'clock"). |
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210 | |
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211 | While most event loops expect timers to specified in a relative way, they use |
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212 | absolute time internally. This makes a difference when your clock "jumps", |
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213 | for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to |
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214 | 2008-01-01, a watcher that you created to fire "after" a second might actually take |
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215 | six years to finally fire. |
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216 | |
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217 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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218 | about these issues is L<EV>, which offers both relative (ev_timer) and |
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219 | absolute (ev_periodic) timers. |
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220 | |
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221 | AnyEvent always prefers relative timers, if available, matching the |
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222 | AnyEvent API. |
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223 | |
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224 | =head2 SIGNAL WATCHERS |
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225 | |
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226 | You can watch for signals using a signal watcher, C<signal> is the signal |
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227 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
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228 | be invoked whenever a signal occurs. |
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229 | |
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230 | Multiple signals occurances can be clumped together into one callback |
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231 | invocation, and callback invocation will be synchronous. synchronous means |
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232 | that it might take a while until the signal gets handled by the process, |
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233 | but it is guarenteed not to interrupt any other callbacks. |
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234 | |
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235 | The main advantage of using these watchers is that you can share a signal |
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236 | between multiple watchers. |
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237 | |
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238 | This watcher might use C<%SIG>, so programs overwriting those signals |
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239 | directly will likely not work correctly. |
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240 | |
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241 | Example: exit on SIGINT |
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242 | |
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243 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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244 | |
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245 | =head2 CHILD PROCESS WATCHERS |
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246 | |
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247 | You can also watch on a child process exit and catch its exit status. |
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248 | |
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249 | The child process is specified by the C<pid> argument (if set to C<0>, it |
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250 | watches for any child process exit). The watcher will trigger as often |
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251 | as status change for the child are received. This works by installing a |
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252 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
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253 | and exit status (as returned by waitpid). |
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254 | |
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255 | Example: wait for pid 1333 |
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256 | |
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257 | my $w = AnyEvent->child ( |
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258 | pid => 1333, |
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259 | cb => sub { |
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260 | my ($pid, $status) = @_; |
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261 | warn "pid $pid exited with status $status"; |
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262 | }, |
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263 | ); |
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264 | |
116 | =head2 CONDITION WATCHERS |
265 | =head2 CONDITION VARIABLES |
117 | |
266 | |
118 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
267 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
119 | method without any arguments. |
268 | method without any arguments. |
120 | |
269 | |
121 | A condition watcher watches for a condition - precisely that the C<< |
270 | A condition variable waits for a condition - precisely that the C<< |
122 | ->broadcast >> method has been called. |
271 | ->broadcast >> method has been called. |
123 | |
272 | |
124 | The watcher has only two methods: |
273 | They are very useful to signal that a condition has been fulfilled, for |
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274 | example, if you write a module that does asynchronous http requests, |
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275 | then a condition variable would be the ideal candidate to signal the |
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276 | availability of results. |
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277 | |
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278 | You can also use condition variables to block your main program until |
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279 | an event occurs - for example, you could C<< ->wait >> in your main |
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280 | program until the user clicks the Quit button in your app, which would C<< |
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281 | ->broadcast >> the "quit" event. |
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282 | |
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283 | Note that condition variables recurse into the event loop - if you have |
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284 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
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285 | lose. Therefore, condition variables are good to export to your caller, but |
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286 | you should avoid making a blocking wait yourself, at least in callbacks, |
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287 | as this asks for trouble. |
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288 | |
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289 | This object has two methods: |
125 | |
290 | |
126 | =over 4 |
291 | =over 4 |
127 | |
292 | |
128 | =item $cv->wait |
293 | =item $cv->wait |
129 | |
294 | |
130 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
295 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
131 | called on c<$cv>, while servicing other watchers normally. |
296 | called on c<$cv>, while servicing other watchers normally. |
132 | |
297 | |
133 | Not all event models support a blocking wait - some die in that case, so |
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134 | if you are using this from a module, never require a blocking wait, but |
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135 | let the caller decide wether the call will block or not (for example, |
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136 | by coupling condition variables with some kind of request results and |
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137 | supporting callbacks so the caller knows that getting the result will not |
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138 | block, while still suppporting blockign waits if the caller so desires). |
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139 | |
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140 | You can only wait once on a condition - additional calls will return |
298 | You can only wait once on a condition - additional calls will return |
141 | immediately. |
299 | immediately. |
142 | |
300 | |
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301 | Not all event models support a blocking wait - some die in that case |
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302 | (programs might want to do that to stay interactive), so I<if you are |
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303 | using this from a module, never require a blocking wait>, but let the |
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304 | caller decide whether the call will block or not (for example, by coupling |
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305 | condition variables with some kind of request results and supporting |
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306 | callbacks so the caller knows that getting the result will not block, |
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307 | while still suppporting blocking waits if the caller so desires). |
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308 | |
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309 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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310 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
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311 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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312 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
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313 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
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314 | from different coroutines, however). |
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315 | |
143 | =item $cv->broadcast |
316 | =item $cv->broadcast |
144 | |
317 | |
145 | Flag the condition as ready - a running C<< ->wait >> and all further |
318 | Flag the condition as ready - a running C<< ->wait >> and all further |
146 | calls to C<wait> will return after this method has been called. If nobody |
319 | calls to C<wait> will (eventually) return after this method has been |
147 | is waiting the broadcast will be remembered.. |
320 | called. If nobody is waiting the broadcast will be remembered.. |
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321 | |
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322 | =back |
148 | |
323 | |
149 | Example: |
324 | Example: |
150 | |
325 | |
151 | # wait till the result is ready |
326 | # wait till the result is ready |
152 | my $result_ready = AnyEvent->condvar; |
327 | my $result_ready = AnyEvent->condvar; |
153 | |
328 | |
154 | # do something such as adding a timer |
329 | # do something such as adding a timer |
155 | # or socket watcher the calls $result_ready->broadcast |
330 | # or socket watcher the calls $result_ready->broadcast |
156 | # when the "result" is ready. |
331 | # when the "result" is ready. |
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332 | # in this case, we simply use a timer: |
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333 | my $w = AnyEvent->timer ( |
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334 | after => 1, |
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335 | cb => sub { $result_ready->broadcast }, |
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336 | ); |
157 | |
337 | |
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338 | # this "blocks" (while handling events) till the watcher |
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339 | # calls broadcast |
158 | $result_ready->wait; |
340 | $result_ready->wait; |
159 | |
341 | |
160 | =back |
342 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
161 | |
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162 | =head2 SIGNAL WATCHERS |
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163 | |
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164 | You can listen for signals using a signal watcher, C<signal> is the signal |
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165 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
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166 | together into one callback invocation, and callback invocation might or |
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167 | might not be asynchronous. |
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168 | |
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169 | These watchers might use C<%SIG>, so programs overwriting those signals |
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170 | directly will likely not work correctly. |
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171 | |
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172 | Example: exit on SIGINT |
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173 | |
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174 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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175 | |
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176 | =head2 CHILD PROCESS WATCHERS |
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177 | |
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178 | You can also listen for the status of a child process specified by the |
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179 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
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180 | trigger as often as status change for the child are received. This works |
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181 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
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182 | the pid and exit status (as returned by waitpid). |
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183 | |
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184 | Example: wait for pid 1333 |
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185 | |
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186 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
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187 | |
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188 | =head1 GLOBALS |
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189 | |
343 | |
190 | =over 4 |
344 | =over 4 |
191 | |
345 | |
192 | =item $AnyEvent::MODEL |
346 | =item $AnyEvent::MODEL |
193 | |
347 | |
… | |
… | |
198 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
352 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
199 | |
353 | |
200 | The known classes so far are: |
354 | The known classes so far are: |
201 | |
355 | |
202 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
356 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
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357 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
203 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
358 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
204 | AnyEvent::Impl::Coro based on Coro::Event, second best choice. |
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205 | AnyEvent::Impl::Event based on Event, also second best choice :) |
359 | AnyEvent::Impl::Event based on Event, also second best choice :) |
206 | AnyEvent::Impl::Glib based on Glib, second-best choice. |
360 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
207 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
361 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
208 | AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
362 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
209 | |
363 | |
210 | =item AnyEvent::detect |
364 | =item AnyEvent::detect |
211 | |
365 | |
212 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
366 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
213 | necessary. You should only call this function right before you would have |
367 | if necessary. You should only call this function right before you would |
214 | created an AnyEvent watcher anyway, that is, very late at runtime. |
368 | have created an AnyEvent watcher anyway, that is, as late as possible at |
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369 | runtime. |
215 | |
370 | |
216 | =back |
371 | =back |
217 | |
372 | |
218 | =head1 WHAT TO DO IN A MODULE |
373 | =head1 WHAT TO DO IN A MODULE |
219 | |
374 | |
220 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
375 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
221 | freely, but you should not load a specific event module or rely on it. |
376 | freely, but you should not load a specific event module or rely on it. |
222 | |
377 | |
223 | Be careful when you create watchers in the module body - Anyevent will |
378 | Be careful when you create watchers in the module body - AnyEvent will |
224 | decide which event module to use as soon as the first method is called, so |
379 | decide which event module to use as soon as the first method is called, so |
225 | by calling AnyEvent in your module body you force the user of your module |
380 | by calling AnyEvent in your module body you force the user of your module |
226 | to load the event module first. |
381 | to load the event module first. |
227 | |
382 | |
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383 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
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384 | the C<< ->broadcast >> method has been called on it already. This is |
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385 | because it will stall the whole program, and the whole point of using |
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386 | events is to stay interactive. |
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387 | |
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388 | It is fine, however, to call C<< ->wait >> when the user of your module |
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389 | requests it (i.e. if you create a http request object ad have a method |
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390 | called C<results> that returns the results, it should call C<< ->wait >> |
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391 | freely, as the user of your module knows what she is doing. always). |
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392 | |
228 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
393 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
229 | |
394 | |
230 | There will always be a single main program - the only place that should |
395 | There will always be a single main program - the only place that should |
231 | dictate which event model to use. |
396 | dictate which event model to use. |
232 | |
397 | |
233 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
398 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
234 | do anything special and let AnyEvent decide which implementation to chose. |
399 | do anything special (it does not need to be event-based) and let AnyEvent |
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400 | decide which implementation to chose if some module relies on it. |
235 | |
401 | |
236 | If the main program relies on a specific event model (for example, in Gtk2 |
402 | If the main program relies on a specific event model. For example, in |
237 | programs you have to rely on either Glib or Glib::Event), you should load |
403 | Gtk2 programs you have to rely on the Glib module. You should load the |
238 | it before loading AnyEvent or any module that uses it, generally, as early |
404 | event module before loading AnyEvent or any module that uses it: generally |
239 | as possible. The reason is that modules might create watchers when they |
405 | speaking, you should load it as early as possible. The reason is that |
240 | are loaded, and AnyEvent will decide on the event model to use as soon as |
406 | modules might create watchers when they are loaded, and AnyEvent will |
241 | it creates watchers, and it might chose the wrong one unless you load the |
407 | decide on the event model to use as soon as it creates watchers, and it |
242 | correct one yourself. |
408 | might chose the wrong one unless you load the correct one yourself. |
243 | |
409 | |
244 | You can chose to use a rather inefficient pure-perl implementation by |
410 | You can chose to use a rather inefficient pure-perl implementation by |
245 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
411 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
246 | generally better. |
412 | behaviour everywhere, but letting AnyEvent chose is generally better. |
247 | |
413 | |
248 | =cut |
414 | =cut |
249 | |
415 | |
250 | package AnyEvent; |
416 | package AnyEvent; |
251 | |
417 | |
252 | no warnings; |
418 | no warnings; |
253 | use strict; |
419 | use strict; |
254 | |
420 | |
255 | use Carp; |
421 | use Carp; |
256 | |
422 | |
257 | our $VERSION = '2.8'; |
423 | our $VERSION = '3.11'; |
258 | our $MODEL; |
424 | our $MODEL; |
259 | |
425 | |
260 | our $AUTOLOAD; |
426 | our $AUTOLOAD; |
261 | our @ISA; |
427 | our @ISA; |
262 | |
428 | |
… | |
… | |
264 | |
430 | |
265 | our @REGISTRY; |
431 | our @REGISTRY; |
266 | |
432 | |
267 | my @models = ( |
433 | my @models = ( |
268 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
434 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
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435 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
269 | [EV:: => AnyEvent::Impl::EV::], |
436 | [EV:: => AnyEvent::Impl::EV::], |
270 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
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271 | [Event:: => AnyEvent::Impl::Event::], |
437 | [Event:: => AnyEvent::Impl::Event::], |
272 | [Glib:: => AnyEvent::Impl::Glib::], |
438 | [Glib:: => AnyEvent::Impl::Glib::], |
273 | [Tk:: => AnyEvent::Impl::Tk::], |
439 | [Tk:: => AnyEvent::Impl::Tk::], |
274 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
440 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
275 | ); |
441 | ); |
… | |
… | |
426 | undef $CHLD_W unless keys %PID_CB; |
592 | undef $CHLD_W unless keys %PID_CB; |
427 | } |
593 | } |
428 | |
594 | |
429 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
595 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
430 | |
596 | |
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597 | This is an advanced topic that you do not normally need to use AnyEvent in |
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598 | a module. This section is only of use to event loop authors who want to |
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599 | provide AnyEvent compatibility. |
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|
600 | |
431 | If you need to support another event library which isn't directly |
601 | If you need to support another event library which isn't directly |
432 | supported by AnyEvent, you can supply your own interface to it by |
602 | supported by AnyEvent, you can supply your own interface to it by |
433 | pushing, before the first watcher gets created, the package name of |
603 | pushing, before the first watcher gets created, the package name of |
434 | the event module and the package name of the interface to use onto |
604 | the event module and the package name of the interface to use onto |
435 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
605 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
436 | AnyEvent. |
606 | AnyEvent, so it is reasonably cheap. |
437 | |
607 | |
438 | Example: |
608 | Example: |
439 | |
609 | |
440 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
610 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
441 | |
611 | |
442 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
612 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
443 | package/class when it finds the C<urxvt> package/module is loaded. When |
613 | package/class when it finds the C<urxvt> package/module is already loaded. |
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|
614 | |
444 | AnyEvent is loaded and asked to find a suitable event model, it will |
615 | When AnyEvent is loaded and asked to find a suitable event model, it |
445 | first check for the presence of urxvt. |
616 | will first check for the presence of urxvt by trying to C<use> the |
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|
617 | C<urxvt::anyevent> module. |
446 | |
618 | |
447 | The class should provide implementations for all watcher types (see |
619 | The class should provide implementations for all watcher types. See |
448 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
620 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
449 | (Source code) and so on for actual examples, use C<perldoc -m |
621 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
450 | AnyEvent::Impl::Glib> to see the sources). |
622 | see the sources. |
451 | |
623 | |
|
|
624 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
625 | provide suitable (hopefully) replacements. |
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|
626 | |
452 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
627 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
453 | uses the above line as-is. An interface isn't included in AnyEvent |
628 | terminal emulator uses the above line as-is. An interface isn't included |
454 | because it doesn't make sense outside the embedded interpreter inside |
629 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
455 | I<rxvt-unicode>, and it is updated and maintained as part of the |
630 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
456 | I<rxvt-unicode> distribution. |
631 | I<rxvt-unicode> distribution. |
457 | |
632 | |
458 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
633 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
459 | condition variables: code blocking while waiting for a condition will |
634 | condition variables: code blocking while waiting for a condition will |
460 | C<die>. This still works with most modules/usages, and blocking calls must |
635 | C<die>. This still works with most modules/usages, and blocking calls must |
461 | not be in an interactive application, so it makes sense. |
636 | not be done in an interactive application, so it makes sense. |
462 | |
637 | |
463 | =head1 ENVIRONMENT VARIABLES |
638 | =head1 ENVIRONMENT VARIABLES |
464 | |
639 | |
465 | The following environment variables are used by this module: |
640 | The following environment variables are used by this module: |
466 | |
641 | |
467 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
642 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, cause AnyEvent to |
468 | model gets used. |
643 | report to STDERR which event model it chooses. |
469 | |
644 | |
470 | =head1 EXAMPLE |
645 | =head1 EXAMPLE PROGRAM |
471 | |
646 | |
472 | The following program uses an io watcher to read data from stdin, a timer |
647 | The following program uses an IO watcher to read data from STDIN, a timer |
473 | to display a message once per second, and a condvar to exit the program |
648 | to display a message once per second, and a condition variable to quit the |
474 | when the user enters quit: |
649 | program when the user enters quit: |
475 | |
650 | |
476 | use AnyEvent; |
651 | use AnyEvent; |
477 | |
652 | |
478 | my $cv = AnyEvent->condvar; |
653 | my $cv = AnyEvent->condvar; |
479 | |
654 | |
480 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
655 | my $io_watcher = AnyEvent->io ( |
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|
656 | fh => \*STDIN, |
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|
657 | poll => 'r', |
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|
658 | cb => sub { |
481 | warn "io event <$_[0]>\n"; # will always output <r> |
659 | warn "io event <$_[0]>\n"; # will always output <r> |
482 | chomp (my $input = <STDIN>); # read a line |
660 | chomp (my $input = <STDIN>); # read a line |
483 | warn "read: $input\n"; # output what has been read |
661 | warn "read: $input\n"; # output what has been read |
484 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
662 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
|
|
663 | }, |
485 | }); |
664 | ); |
486 | |
665 | |
487 | my $time_watcher; # can only be used once |
666 | my $time_watcher; # can only be used once |
488 | |
667 | |
489 | sub new_timer { |
668 | sub new_timer { |
490 | $timer = AnyEvent->timer (after => 1, cb => sub { |
669 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
572 | $txn->{finished}->wait; |
751 | $txn->{finished}->wait; |
573 | return $txn->{result}; |
752 | return $txn->{result}; |
574 | |
753 | |
575 | The actual code goes further and collects all errors (C<die>s, exceptions) |
754 | The actual code goes further and collects all errors (C<die>s, exceptions) |
576 | that occured during request processing. The C<result> method detects |
755 | that occured during request processing. The C<result> method detects |
577 | wether an exception as thrown (it is stored inside the $txn object) |
756 | whether an exception as thrown (it is stored inside the $txn object) |
578 | and just throws the exception, which means connection errors and other |
757 | and just throws the exception, which means connection errors and other |
579 | problems get reported tot he code that tries to use the result, not in a |
758 | problems get reported tot he code that tries to use the result, not in a |
580 | random callback. |
759 | random callback. |
581 | |
760 | |
582 | All of this enables the following usage styles: |
761 | All of this enables the following usage styles: |
583 | |
762 | |
584 | 1. Blocking: |
763 | 1. Blocking: |
585 | |
764 | |
586 | my $data = $fcp->client_get ($url); |
765 | my $data = $fcp->client_get ($url); |
587 | |
766 | |
588 | 2. Blocking, but parallelizing: |
767 | 2. Blocking, but running in parallel: |
589 | |
768 | |
590 | my @datas = map $_->result, |
769 | my @datas = map $_->result, |
591 | map $fcp->txn_client_get ($_), |
770 | map $fcp->txn_client_get ($_), |
592 | @urls; |
771 | @urls; |
593 | |
772 | |
594 | Both blocking examples work without the module user having to know |
773 | Both blocking examples work without the module user having to know |
595 | anything about events. |
774 | anything about events. |
596 | |
775 | |
597 | 3a. Event-based in a main program, using any support Event module: |
776 | 3a. Event-based in a main program, using any supported event module: |
598 | |
777 | |
599 | use Event; |
778 | use EV; |
600 | |
779 | |
601 | $fcp->txn_client_get ($url)->cb (sub { |
780 | $fcp->txn_client_get ($url)->cb (sub { |
602 | my $txn = shift; |
781 | my $txn = shift; |
603 | my $data = $txn->result; |
782 | my $data = $txn->result; |
604 | ... |
783 | ... |
605 | }); |
784 | }); |
606 | |
785 | |
607 | Event::loop; |
786 | EV::loop; |
608 | |
787 | |
609 | 3b. The module user could use AnyEvent, too: |
788 | 3b. The module user could use AnyEvent, too: |
610 | |
789 | |
611 | use AnyEvent; |
790 | use AnyEvent; |
612 | |
791 | |
… | |
… | |
619 | |
798 | |
620 | $quit->wait; |
799 | $quit->wait; |
621 | |
800 | |
622 | =head1 SEE ALSO |
801 | =head1 SEE ALSO |
623 | |
802 | |
624 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
803 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
|
|
804 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
625 | |
805 | |
626 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
806 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
|
|
807 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
|
|
808 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
627 | |
809 | |
628 | Nontrivial usage example: L<Net::FCP>. |
810 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
629 | |
811 | |
630 | =head1 |
812 | =head1 |
631 | |
813 | |
632 | =cut |
814 | =cut |
633 | |
815 | |