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 - 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 | |
11 | my $w = AnyEvent->io (fh => ..., poll => "[rw]+", cb => sub { |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
12 | my ($poll_got) = @_; |
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13 | ... |
12 | ... |
14 | }); |
13 | }); |
15 | |
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16 | * only one io watcher per $fh and $poll type is allowed (i.e. on a socket |
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17 | you can have one r + one w or one rw watcher, not any more (limitation by |
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18 | Tk). |
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19 | |
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20 | * the C<$poll_got> passed to the handler needs to be checked by looking |
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21 | for single characters (e.g. with a regex), as it can contain more event |
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22 | types than were requested (e.g. a 'w' watcher might generate 'rw' events, |
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23 | limitation by Glib). |
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24 | |
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25 | * AnyEvent will keep filehandles alive, so as long as the watcher exists, |
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26 | the filehandle exists. |
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27 | |
14 | |
28 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
29 | ... |
16 | ... |
30 | }); |
17 | }); |
31 | |
18 | |
32 | * io and time watchers get canceled whenever $w is destroyed, so keep a copy |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
33 | |
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34 | * timers can only be used once and must be recreated for repeated |
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35 | operation (limitation by Glib and Tk). |
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36 | |
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37 | my $w = AnyEvent->condvar; # kind of main loop replacement |
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38 | $w->wait; # enters main loop till $condvar gets ->broadcast |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
39 | $w->broadcast; # wake up current and all future wait's |
21 | $w->broadcast; # wake up current and all future wait's |
40 | |
22 | |
41 | * condvars are used to give blocking behaviour when neccessary. Create |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
42 | a condvar for any "request" or "event" your module might create, C<< |
24 | |
43 | ->broadcast >> it when the event happens and provide a function that calls |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
44 | C<< ->wait >> for it. See the examples below. |
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 | |
45 | |
71 | |
46 | =head1 DESCRIPTION |
72 | =head1 DESCRIPTION |
47 | |
73 | |
48 | L<AnyEvent> provides an identical interface to multiple event loops. This |
74 | L<AnyEvent> provides an identical interface to multiple event loops. This |
49 | allows module authors to utilizy an event loop without forcing module |
75 | allows module authors to utilise an event loop without forcing module |
50 | 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 |
51 | peacefully at any one time). |
77 | peacefully at any one time). |
52 | |
78 | |
53 | 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> |
54 | module. |
80 | module. |
55 | |
81 | |
56 | 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 |
57 | 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 |
58 | 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>, |
59 | 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>, |
60 | 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 |
61 | used. If still none could be found, it will issue an error. |
87 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
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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. |
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92 | |
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93 | Because AnyEvent first checks for modules that are already loaded, loading |
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94 | an event model explicitly before first using AnyEvent will likely make |
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95 | that model the default. For example: |
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96 | |
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97 | use Tk; |
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98 | use AnyEvent; |
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99 | |
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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... |
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105 | |
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106 | The pure-perl implementation of AnyEvent is called |
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107 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
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108 | explicitly. |
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109 | |
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110 | =head1 WATCHERS |
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111 | |
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112 | AnyEvent has the central concept of a I<watcher>, which is an object that |
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113 | stores relevant data for each kind of event you are waiting for, such as |
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114 | the callback to call, the filehandle to watch, etc. |
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115 | |
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116 | These watchers are normal Perl objects with normal Perl lifetime. After |
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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 | |
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121 | To disable the watcher you have to destroy it (e.g. by setting the |
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122 | variable you store it in to C<undef> or otherwise deleting all references |
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123 | to it). |
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124 | |
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125 | All watchers are created by calling a method on the C<AnyEvent> class. |
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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 | |
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141 | =head2 I/O WATCHERS |
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142 | |
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143 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
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144 | with the following mandatory key-value pairs as arguments: |
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145 | |
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146 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch |
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147 | for events. C<poll> must be a string that is either C<r> or C<w>, |
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148 | which creates a watcher waiting for "r"eadable or "w"ritable events, |
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149 | respectively. C<cb> is the callback to invoke each time the file handle |
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150 | becomes ready. |
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151 | |
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152 | Although the callback might get passed parameters, their value and |
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153 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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154 | callbacks cannot use arguments passed to I/O watcher callbacks. |
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155 | |
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156 | The I/O watcher might use the underlying file descriptor or a copy of it. |
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157 | You must not close a file handle as long as any watcher is active on the |
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158 | underlying file descriptor. |
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159 | |
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160 | Some event loops issue spurious readyness notifications, so you should |
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161 | always use non-blocking calls when reading/writing from/to your file |
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162 | handles. |
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163 | |
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164 | Example: |
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165 | |
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166 | # wait for readability of STDIN, then read a line and disable the watcher |
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167 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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168 | chomp (my $input = <STDIN>); |
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169 | warn "read: $input\n"; |
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170 | undef $w; |
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171 | }); |
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172 | |
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173 | =head2 TIME WATCHERS |
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174 | |
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175 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
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176 | method with the following mandatory arguments: |
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177 | |
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178 | C<after> specifies after how many seconds (fractional values are |
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179 | supported) the callback should be invoked. C<cb> is the callback to invoke |
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180 | in that case. |
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181 | |
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182 | Although the callback might get passed parameters, their value and |
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183 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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184 | callbacks cannot use arguments passed to time watcher callbacks. |
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185 | |
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186 | The timer callback will be invoked at most once: if you want a repeating |
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187 | timer you have to create a new watcher (this is a limitation by both Tk |
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188 | and Glib). |
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189 | |
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190 | Example: |
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191 | |
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192 | # fire an event after 7.7 seconds |
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193 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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194 | warn "timeout\n"; |
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195 | }); |
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196 | |
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197 | # to cancel the timer: |
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198 | undef $w; |
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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 | Although the callback might get passed parameters, their value and |
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240 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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241 | callbacks cannot use arguments passed to signal watcher callbacks. |
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242 | |
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243 | Multiple signal occurances can be clumped together into one callback |
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244 | invocation, and callback invocation will be synchronous. synchronous means |
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245 | that it might take a while until the signal gets handled by the process, |
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246 | but it is guarenteed not to interrupt any other callbacks. |
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247 | |
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248 | The main advantage of using these watchers is that you can share a signal |
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249 | between multiple watchers. |
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250 | |
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251 | This watcher might use C<%SIG>, so programs overwriting those signals |
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252 | directly will likely not work correctly. |
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253 | |
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254 | Example: exit on SIGINT |
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255 | |
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256 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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257 | |
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258 | =head2 CHILD PROCESS WATCHERS |
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259 | |
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260 | You can also watch on a child process exit and catch its exit status. |
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261 | |
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262 | The child process is specified by the C<pid> argument (if set to C<0>, it |
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263 | watches for any child process exit). The watcher will trigger as often |
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264 | as status change for the child are received. This works by installing a |
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265 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
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266 | and exit status (as returned by waitpid), so unlike other watcher types, |
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267 | you I<can> rely on child watcher callback arguments. |
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268 | |
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269 | There is a slight catch to child watchers, however: you usually start them |
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270 | I<after> the child process was created, and this means the process could |
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271 | have exited already (and no SIGCHLD will be sent anymore). |
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272 | |
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273 | Not all event models handle this correctly (POE doesn't), but even for |
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274 | event models that I<do> handle this correctly, they usually need to be |
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275 | loaded before the process exits (i.e. before you fork in the first place). |
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276 | |
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277 | This means you cannot create a child watcher as the very first thing in an |
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278 | AnyEvent program, you I<have> to create at least one watcher before you |
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279 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
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280 | |
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281 | Example: fork a process and wait for it |
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282 | |
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283 | my $done = AnyEvent->condvar; |
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284 | |
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285 | AnyEvent::detect; # force event module to be initialised |
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286 | |
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287 | my $pid = fork or exit 5; |
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288 | |
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289 | my $w = AnyEvent->child ( |
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290 | pid => $pid, |
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291 | cb => sub { |
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292 | my ($pid, $status) = @_; |
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293 | warn "pid $pid exited with status $status"; |
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294 | $done->broadcast; |
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295 | }, |
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296 | ); |
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297 | |
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298 | # do something else, then wait for process exit |
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299 | $done->wait; |
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300 | |
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301 | =head2 CONDITION VARIABLES |
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302 | |
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303 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
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304 | method without any arguments. |
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305 | |
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306 | A condition variable waits for a condition - precisely that the C<< |
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307 | ->broadcast >> method has been called. |
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308 | |
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309 | They are very useful to signal that a condition has been fulfilled, for |
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310 | example, if you write a module that does asynchronous http requests, |
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311 | then a condition variable would be the ideal candidate to signal the |
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312 | availability of results. |
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313 | |
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314 | You can also use condition variables to block your main program until |
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315 | an event occurs - for example, you could C<< ->wait >> in your main |
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316 | program until the user clicks the Quit button in your app, which would C<< |
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317 | ->broadcast >> the "quit" event. |
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318 | |
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319 | Note that condition variables recurse into the event loop - if you have |
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320 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
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321 | lose. Therefore, condition variables are good to export to your caller, but |
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322 | you should avoid making a blocking wait yourself, at least in callbacks, |
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323 | as this asks for trouble. |
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324 | |
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325 | This object has two methods: |
62 | |
326 | |
63 | =over 4 |
327 | =over 4 |
64 | |
328 | |
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329 | =item $cv->wait |
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330 | |
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331 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
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332 | called on c<$cv>, while servicing other watchers normally. |
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333 | |
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334 | You can only wait once on a condition - additional calls will return |
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335 | immediately. |
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336 | |
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337 | Not all event models support a blocking wait - some die in that case |
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338 | (programs might want to do that to stay interactive), so I<if you are |
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339 | using this from a module, never require a blocking wait>, but let the |
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340 | caller decide whether the call will block or not (for example, by coupling |
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341 | condition variables with some kind of request results and supporting |
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342 | callbacks so the caller knows that getting the result will not block, |
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343 | while still suppporting blocking waits if the caller so desires). |
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344 | |
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345 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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346 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
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347 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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348 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
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349 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
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350 | from different coroutines, however). |
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351 | |
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352 | =item $cv->broadcast |
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353 | |
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354 | Flag the condition as ready - a running C<< ->wait >> and all further |
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355 | calls to C<wait> will (eventually) return after this method has been |
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356 | called. If nobody is waiting the broadcast will be remembered.. |
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357 | |
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358 | =back |
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359 | |
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360 | Example: |
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361 | |
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362 | # wait till the result is ready |
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363 | my $result_ready = AnyEvent->condvar; |
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364 | |
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365 | # do something such as adding a timer |
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366 | # or socket watcher the calls $result_ready->broadcast |
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367 | # when the "result" is ready. |
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368 | # in this case, we simply use a timer: |
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369 | my $w = AnyEvent->timer ( |
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370 | after => 1, |
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371 | cb => sub { $result_ready->broadcast }, |
|
|
372 | ); |
|
|
373 | |
|
|
374 | # this "blocks" (while handling events) till the watcher |
|
|
375 | # calls broadcast |
|
|
376 | $result_ready->wait; |
|
|
377 | |
|
|
378 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
|
|
379 | |
|
|
380 | =over 4 |
|
|
381 | |
|
|
382 | =item $AnyEvent::MODEL |
|
|
383 | |
|
|
384 | Contains C<undef> until the first watcher is being created. Then it |
|
|
385 | contains the event model that is being used, which is the name of the |
|
|
386 | Perl class implementing the model. This class is usually one of the |
|
|
387 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
|
|
388 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
|
|
389 | |
|
|
390 | The known classes so far are: |
|
|
391 | |
|
|
392 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
|
|
393 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
|
|
394 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
|
|
395 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
396 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
397 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
|
|
398 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
|
|
399 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
400 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
401 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
402 | |
|
|
403 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
404 | watching file handles. However, you can use WxWidgets through the |
|
|
405 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
406 | second, which was considered to be too horrible to even consider for |
|
|
407 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
408 | it's adaptor. |
|
|
409 | |
|
|
410 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
411 | autodetecting them. |
|
|
412 | |
|
|
413 | =item AnyEvent::detect |
|
|
414 | |
|
|
415 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
|
|
416 | if necessary. You should only call this function right before you would |
|
|
417 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
418 | runtime. |
|
|
419 | |
|
|
420 | =back |
|
|
421 | |
|
|
422 | =head1 WHAT TO DO IN A MODULE |
|
|
423 | |
|
|
424 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
|
|
425 | freely, but you should not load a specific event module or rely on it. |
|
|
426 | |
|
|
427 | Be careful when you create watchers in the module body - AnyEvent will |
|
|
428 | decide which event module to use as soon as the first method is called, so |
|
|
429 | by calling AnyEvent in your module body you force the user of your module |
|
|
430 | to load the event module first. |
|
|
431 | |
|
|
432 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
|
|
433 | the C<< ->broadcast >> method has been called on it already. This is |
|
|
434 | because it will stall the whole program, and the whole point of using |
|
|
435 | events is to stay interactive. |
|
|
436 | |
|
|
437 | It is fine, however, to call C<< ->wait >> when the user of your module |
|
|
438 | requests it (i.e. if you create a http request object ad have a method |
|
|
439 | called C<results> that returns the results, it should call C<< ->wait >> |
|
|
440 | freely, as the user of your module knows what she is doing. always). |
|
|
441 | |
|
|
442 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
|
|
443 | |
|
|
444 | There will always be a single main program - the only place that should |
|
|
445 | dictate which event model to use. |
|
|
446 | |
|
|
447 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
|
|
448 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
449 | decide which implementation to chose if some module relies on it. |
|
|
450 | |
|
|
451 | If the main program relies on a specific event model. For example, in |
|
|
452 | Gtk2 programs you have to rely on the Glib module. You should load the |
|
|
453 | event module before loading AnyEvent or any module that uses it: generally |
|
|
454 | speaking, you should load it as early as possible. The reason is that |
|
|
455 | modules might create watchers when they are loaded, and AnyEvent will |
|
|
456 | decide on the event model to use as soon as it creates watchers, and it |
|
|
457 | might chose the wrong one unless you load the correct one yourself. |
|
|
458 | |
|
|
459 | You can chose to use a rather inefficient pure-perl implementation by |
|
|
460 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
|
|
461 | behaviour everywhere, but letting AnyEvent chose is generally better. |
|
|
462 | |
65 | =cut |
463 | =cut |
66 | |
464 | |
67 | package AnyEvent; |
465 | package AnyEvent; |
68 | |
466 | |
69 | no warnings; |
467 | no warnings; |
70 | use strict 'vars'; |
468 | use strict; |
|
|
469 | |
71 | use Carp; |
470 | use Carp; |
72 | |
471 | |
73 | our $VERSION = '1.02'; |
472 | our $VERSION = '3.3'; |
74 | our $MODEL; |
473 | our $MODEL; |
75 | |
474 | |
76 | our $AUTOLOAD; |
475 | our $AUTOLOAD; |
77 | our @ISA; |
476 | our @ISA; |
78 | |
477 | |
79 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
478 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
80 | |
479 | |
81 | our @REGISTRY; |
480 | our @REGISTRY; |
82 | |
481 | |
83 | my @models = ( |
482 | my @models = ( |
|
|
483 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
84 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
484 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
485 | [EV:: => AnyEvent::Impl::EV::], |
85 | [Event:: => AnyEvent::Impl::Event::], |
486 | [Event:: => AnyEvent::Impl::Event::], |
86 | [Glib:: => AnyEvent::Impl::Glib::], |
487 | [Glib:: => AnyEvent::Impl::Glib::], |
87 | [Tk:: => AnyEvent::Impl::Tk::], |
488 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
489 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
490 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
491 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
492 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
|
|
493 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
494 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
495 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
88 | ); |
496 | ); |
89 | |
497 | |
90 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY); |
498 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
91 | |
499 | |
92 | sub AUTOLOAD { |
500 | sub detect() { |
93 | $AUTOLOAD =~ s/.*://; |
|
|
94 | |
|
|
95 | $method{$AUTOLOAD} |
|
|
96 | or croak "$AUTOLOAD: not a valid method for AnyEvent objects"; |
|
|
97 | |
|
|
98 | unless ($MODEL) { |
501 | unless ($MODEL) { |
|
|
502 | no strict 'refs'; |
|
|
503 | |
|
|
504 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
505 | my $model = "AnyEvent::Impl::$1"; |
|
|
506 | if (eval "require $model") { |
|
|
507 | $MODEL = $model; |
|
|
508 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
509 | } else { |
|
|
510 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
511 | } |
|
|
512 | } |
|
|
513 | |
99 | # check for already loaded models |
514 | # check for already loaded models |
|
|
515 | unless ($MODEL) { |
100 | for (@REGISTRY, @models) { |
516 | for (@REGISTRY, @models) { |
101 | my ($package, $model) = @$_; |
517 | my ($package, $model) = @$_; |
102 | if (${"$package\::VERSION"} > 0) { |
518 | if (${"$package\::VERSION"} > 0) { |
103 | if (eval "require $model") { |
519 | if (eval "require $model") { |
104 | $MODEL = $model; |
520 | $MODEL = $model; |
105 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
521 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
106 | last; |
522 | last; |
|
|
523 | } |
107 | } |
524 | } |
108 | } |
525 | } |
|
|
526 | |
|
|
527 | unless ($MODEL) { |
|
|
528 | # try to load a model |
|
|
529 | |
|
|
530 | for (@REGISTRY, @models) { |
|
|
531 | my ($package, $model) = @$_; |
|
|
532 | if (eval "require $package" |
|
|
533 | and ${"$package\::VERSION"} > 0 |
|
|
534 | and eval "require $model") { |
|
|
535 | $MODEL = $model; |
|
|
536 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
|
|
537 | last; |
|
|
538 | } |
|
|
539 | } |
|
|
540 | |
|
|
541 | $MODEL |
|
|
542 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; |
|
|
543 | } |
109 | } |
544 | } |
110 | |
545 | |
111 | unless ($MODEL) { |
546 | unshift @ISA, $MODEL; |
112 | # try to load a model |
547 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
113 | |
|
|
114 | for (@REGISTRY, @models) { |
|
|
115 | my ($package, $model) = @$_; |
|
|
116 | if (eval "require $model") { |
|
|
117 | $MODEL = $model; |
|
|
118 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
|
|
119 | last; |
|
|
120 | } |
|
|
121 | } |
|
|
122 | |
|
|
123 | $MODEL |
|
|
124 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk."; |
|
|
125 | } |
|
|
126 | } |
548 | } |
127 | |
549 | |
128 | @ISA = $MODEL; |
550 | $MODEL |
|
|
551 | } |
|
|
552 | |
|
|
553 | sub AUTOLOAD { |
|
|
554 | (my $func = $AUTOLOAD) =~ s/.*://; |
|
|
555 | |
|
|
556 | $method{$func} |
|
|
557 | or croak "$func: not a valid method for AnyEvent objects"; |
|
|
558 | |
|
|
559 | detect unless $MODEL; |
129 | |
560 | |
130 | my $class = shift; |
561 | my $class = shift; |
131 | $class->$AUTOLOAD (@_); |
562 | $class->$func (@_); |
132 | } |
563 | } |
133 | |
564 | |
134 | =back |
565 | package AnyEvent::Base; |
|
|
566 | |
|
|
567 | # default implementation for ->condvar, ->wait, ->broadcast |
|
|
568 | |
|
|
569 | sub condvar { |
|
|
570 | bless \my $flag, "AnyEvent::Base::CondVar" |
|
|
571 | } |
|
|
572 | |
|
|
573 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
574 | ${$_[0]}++; |
|
|
575 | } |
|
|
576 | |
|
|
577 | sub AnyEvent::Base::CondVar::wait { |
|
|
578 | AnyEvent->one_event while !${$_[0]}; |
|
|
579 | } |
|
|
580 | |
|
|
581 | # default implementation for ->signal |
|
|
582 | |
|
|
583 | our %SIG_CB; |
|
|
584 | |
|
|
585 | sub signal { |
|
|
586 | my (undef, %arg) = @_; |
|
|
587 | |
|
|
588 | my $signal = uc $arg{signal} |
|
|
589 | or Carp::croak "required option 'signal' is missing"; |
|
|
590 | |
|
|
591 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
|
|
592 | $SIG{$signal} ||= sub { |
|
|
593 | $_->() for values %{ $SIG_CB{$signal} || {} }; |
|
|
594 | }; |
|
|
595 | |
|
|
596 | bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
|
|
597 | } |
|
|
598 | |
|
|
599 | sub AnyEvent::Base::Signal::DESTROY { |
|
|
600 | my ($signal, $cb) = @{$_[0]}; |
|
|
601 | |
|
|
602 | delete $SIG_CB{$signal}{$cb}; |
|
|
603 | |
|
|
604 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
|
|
605 | } |
|
|
606 | |
|
|
607 | # default implementation for ->child |
|
|
608 | |
|
|
609 | our %PID_CB; |
|
|
610 | our $CHLD_W; |
|
|
611 | our $CHLD_DELAY_W; |
|
|
612 | our $PID_IDLE; |
|
|
613 | our $WNOHANG; |
|
|
614 | |
|
|
615 | sub _child_wait { |
|
|
616 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
|
|
617 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
|
|
618 | (values %{ $PID_CB{0} || {} }); |
|
|
619 | } |
|
|
620 | |
|
|
621 | undef $PID_IDLE; |
|
|
622 | } |
|
|
623 | |
|
|
624 | sub _sigchld { |
|
|
625 | # make sure we deliver these changes "synchronous" with the event loop. |
|
|
626 | $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
|
|
627 | undef $CHLD_DELAY_W; |
|
|
628 | &_child_wait; |
|
|
629 | }); |
|
|
630 | } |
|
|
631 | |
|
|
632 | sub child { |
|
|
633 | my (undef, %arg) = @_; |
|
|
634 | |
|
|
635 | defined (my $pid = $arg{pid} + 0) |
|
|
636 | or Carp::croak "required option 'pid' is missing"; |
|
|
637 | |
|
|
638 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
|
|
639 | |
|
|
640 | unless ($WNOHANG) { |
|
|
641 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
|
|
642 | } |
|
|
643 | |
|
|
644 | unless ($CHLD_W) { |
|
|
645 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
|
|
646 | # child could be a zombie already, so make at least one round |
|
|
647 | &_sigchld; |
|
|
648 | } |
|
|
649 | |
|
|
650 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
|
|
651 | } |
|
|
652 | |
|
|
653 | sub AnyEvent::Base::Child::DESTROY { |
|
|
654 | my ($pid, $cb) = @{$_[0]}; |
|
|
655 | |
|
|
656 | delete $PID_CB{$pid}{$cb}; |
|
|
657 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
|
|
658 | |
|
|
659 | undef $CHLD_W unless keys %PID_CB; |
|
|
660 | } |
135 | |
661 | |
136 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
662 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
663 | |
|
|
664 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
665 | a module. This section is only of use to event loop authors who want to |
|
|
666 | provide AnyEvent compatibility. |
137 | |
667 | |
138 | If you need to support another event library which isn't directly |
668 | If you need to support another event library which isn't directly |
139 | supported by AnyEvent, you can supply your own interface to it by |
669 | supported by AnyEvent, you can supply your own interface to it by |
140 | pushing, before the first watch gets created, the package name of |
670 | pushing, before the first watcher gets created, the package name of |
141 | the event module and the package name of the interface to use onto |
671 | the event module and the package name of the interface to use onto |
142 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
672 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
143 | AnyEvent. |
673 | AnyEvent, so it is reasonably cheap. |
144 | |
674 | |
145 | Example: |
675 | Example: |
146 | |
676 | |
147 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
677 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
148 | |
678 | |
149 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> module |
679 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
150 | when it finds the C<urxvt> module is loaded. When AnyEvent is loaded and |
680 | package/class when it finds the C<urxvt> package/module is already loaded. |
151 | requested to find a suitable event model, it will first check for the |
|
|
152 | urxvt module. |
|
|
153 | |
681 | |
|
|
682 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
683 | will first check for the presence of urxvt by trying to C<use> the |
|
|
684 | C<urxvt::anyevent> module. |
|
|
685 | |
|
|
686 | The class should provide implementations for all watcher types. See |
|
|
687 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
|
|
688 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
|
|
689 | see the sources. |
|
|
690 | |
|
|
691 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
692 | provide suitable (hopefully) replacements. |
|
|
693 | |
154 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) uses |
694 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
155 | the above line exactly. An interface isn't included in AnyEvent |
695 | terminal emulator uses the above line as-is. An interface isn't included |
156 | because it doesn't make sense outside the embedded interpreter inside |
696 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
157 | I<rxvt-unicode>, and it is updated and maintained as part of the |
697 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
158 | I<rxvt-unicode> distribution. |
698 | I<rxvt-unicode> distribution. |
159 | |
699 | |
|
|
700 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
|
|
701 | condition variables: code blocking while waiting for a condition will |
|
|
702 | C<die>. This still works with most modules/usages, and blocking calls must |
|
|
703 | not be done in an interactive application, so it makes sense. |
|
|
704 | |
160 | =head1 ENVIRONMENT VARIABLES |
705 | =head1 ENVIRONMENT VARIABLES |
161 | |
706 | |
162 | The following environment variables are used by this module: |
707 | The following environment variables are used by this module: |
163 | |
708 | |
164 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
709 | =over 4 |
165 | model gets used. |
|
|
166 | |
710 | |
|
|
711 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
712 | |
|
|
713 | By default, AnyEvent will be completely silent except in fatal |
|
|
714 | conditions. You can set this environment variable to make AnyEvent more |
|
|
715 | talkative. |
|
|
716 | |
|
|
717 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
718 | conditions, such as not being able to load the event model specified by |
|
|
719 | C<PERL_ANYEVENT_MODEL>. |
|
|
720 | |
|
|
721 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
722 | model it chooses. |
|
|
723 | |
|
|
724 | =item C<PERL_ANYEVENT_MODEL> |
|
|
725 | |
|
|
726 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
727 | autodetection and -probing kicks in. It must be a string consisting |
|
|
728 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
729 | and the resulting module name is loaded and if the load was successful, |
|
|
730 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
731 | autodetection and -probing. |
|
|
732 | |
|
|
733 | This functionality might change in future versions. |
|
|
734 | |
|
|
735 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
736 | could start your program like this: |
|
|
737 | |
|
|
738 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
739 | |
|
|
740 | =back |
|
|
741 | |
167 | =head1 EXAMPLE |
742 | =head1 EXAMPLE PROGRAM |
168 | |
743 | |
169 | The following program uses an io watcher to read data from stdin, a timer |
744 | The following program uses an I/O watcher to read data from STDIN, a timer |
170 | to display a message once per second, and a condvar to exit the program |
745 | to display a message once per second, and a condition variable to quit the |
171 | when the user enters quit: |
746 | program when the user enters quit: |
172 | |
747 | |
173 | use AnyEvent; |
748 | use AnyEvent; |
174 | |
749 | |
175 | my $cv = AnyEvent->condvar; |
750 | my $cv = AnyEvent->condvar; |
176 | |
751 | |
177 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
752 | my $io_watcher = AnyEvent->io ( |
|
|
753 | fh => \*STDIN, |
|
|
754 | poll => 'r', |
|
|
755 | cb => sub { |
178 | warn "io event <$_[0]>\n"; # will always output <r> |
756 | warn "io event <$_[0]>\n"; # will always output <r> |
179 | chomp (my $input = <STDIN>); # read a line |
757 | chomp (my $input = <STDIN>); # read a line |
180 | warn "read: $input\n"; # output what has been read |
758 | warn "read: $input\n"; # output what has been read |
181 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
759 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
|
|
760 | }, |
182 | }); |
761 | ); |
183 | |
762 | |
184 | my $time_watcher; # can only be used once |
763 | my $time_watcher; # can only be used once |
185 | |
764 | |
186 | sub new_timer { |
765 | sub new_timer { |
187 | $timer = AnyEvent->timer (after => 1, cb => sub { |
766 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
269 | $txn->{finished}->wait; |
848 | $txn->{finished}->wait; |
270 | return $txn->{result}; |
849 | return $txn->{result}; |
271 | |
850 | |
272 | The actual code goes further and collects all errors (C<die>s, exceptions) |
851 | The actual code goes further and collects all errors (C<die>s, exceptions) |
273 | that occured during request processing. The C<result> method detects |
852 | that occured during request processing. The C<result> method detects |
274 | wether an exception as thrown (it is stored inside the $txn object) |
853 | whether an exception as thrown (it is stored inside the $txn object) |
275 | and just throws the exception, which means connection errors and other |
854 | and just throws the exception, which means connection errors and other |
276 | problems get reported tot he code that tries to use the result, not in a |
855 | problems get reported tot he code that tries to use the result, not in a |
277 | random callback. |
856 | random callback. |
278 | |
857 | |
279 | All of this enables the following usage styles: |
858 | All of this enables the following usage styles: |
280 | |
859 | |
281 | 1. Blocking: |
860 | 1. Blocking: |
282 | |
861 | |
283 | my $data = $fcp->client_get ($url); |
862 | my $data = $fcp->client_get ($url); |
284 | |
863 | |
285 | 2. Blocking, but parallelizing: |
864 | 2. Blocking, but running in parallel: |
286 | |
865 | |
287 | my @datas = map $_->result, |
866 | my @datas = map $_->result, |
288 | map $fcp->txn_client_get ($_), |
867 | map $fcp->txn_client_get ($_), |
289 | @urls; |
868 | @urls; |
290 | |
869 | |
291 | Both blocking examples work without the module user having to know |
870 | Both blocking examples work without the module user having to know |
292 | anything about events. |
871 | anything about events. |
293 | |
872 | |
294 | 3a. Event-based in a main program, using any support Event module: |
873 | 3a. Event-based in a main program, using any supported event module: |
295 | |
874 | |
296 | use Event; |
875 | use EV; |
297 | |
876 | |
298 | $fcp->txn_client_get ($url)->cb (sub { |
877 | $fcp->txn_client_get ($url)->cb (sub { |
299 | my $txn = shift; |
878 | my $txn = shift; |
300 | my $data = $txn->result; |
879 | my $data = $txn->result; |
301 | ... |
880 | ... |
302 | }); |
881 | }); |
303 | |
882 | |
304 | Event::loop; |
883 | EV::loop; |
305 | |
884 | |
306 | 3b. The module user could use AnyEvent, too: |
885 | 3b. The module user could use AnyEvent, too: |
307 | |
886 | |
308 | use AnyEvent; |
887 | use AnyEvent; |
309 | |
888 | |
… | |
… | |
314 | $quit->broadcast; |
893 | $quit->broadcast; |
315 | }); |
894 | }); |
316 | |
895 | |
317 | $quit->wait; |
896 | $quit->wait; |
318 | |
897 | |
|
|
898 | |
|
|
899 | =head1 BENCHMARK |
|
|
900 | |
|
|
901 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
902 | over the event loops themselves (and to give you an impression of the |
|
|
903 | speed of various event loops), here is a benchmark of various supported |
|
|
904 | event models natively and with anyevent. The benchmark creates a lot of |
|
|
905 | timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to |
|
|
906 | become writable, which it is), lets them fire exactly once and destroys |
|
|
907 | them again. |
|
|
908 | |
|
|
909 | Rewriting the benchmark to use many different sockets instead of using |
|
|
910 | the same filehandle for all I/O watchers results in a much longer runtime |
|
|
911 | (socket creation is expensive), but qualitatively the same figures, so it |
|
|
912 | was not used. |
|
|
913 | |
|
|
914 | =head2 Explanation of the columns |
|
|
915 | |
|
|
916 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
917 | different event models feature vastly different performances, each event |
|
|
918 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
919 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
920 | would probably take thousands of years if asked to process the same number |
|
|
921 | of watchers as EV in this benchmark. |
|
|
922 | |
|
|
923 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
924 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
925 | and Perl-based overheads. |
|
|
926 | |
|
|
927 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
928 | takes to create a single watcher. The callback is a closure shared between |
|
|
929 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
930 | and memory usage is not included in the figures. |
|
|
931 | |
|
|
932 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
933 | callback. The callback simply counts down a Perl variable and after it was |
|
|
934 | invoked "watcher" times, it would C<< ->broadcast >> a condvar once to |
|
|
935 | signal the end of this phase. |
|
|
936 | |
|
|
937 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
938 | watcher. |
|
|
939 | |
|
|
940 | =head2 Results |
|
|
941 | |
|
|
942 | name watchers bytes create invoke destroy comment |
|
|
943 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
944 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
945 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
946 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
947 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
948 | Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers |
|
|
949 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
950 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
951 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
952 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
953 | |
|
|
954 | =head2 Discussion |
|
|
955 | |
|
|
956 | The benchmark does I<not> measure scalability of the event loop very |
|
|
957 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
958 | can never compete with an event loop that uses epoll when the number of |
|
|
959 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
960 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
961 | boost. |
|
|
962 | |
|
|
963 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
964 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
965 | far less memory than any other event loop and is still faster than Event |
|
|
966 | natively. |
|
|
967 | |
|
|
968 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
969 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
970 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
971 | adds very little overhead in itself. Like any select-based backend its |
|
|
972 | performance becomes really bad with lots of file descriptors (and few of |
|
|
973 | them active), of course, but this was not subject of this benchmark. |
|
|
974 | |
|
|
975 | The C<Event> module has a relatively high setup and callback invocation |
|
|
976 | cost, but overall scores in on the third place. |
|
|
977 | |
|
|
978 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
979 | faster callback invocation and overall ends up in the same class as |
|
|
980 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
981 | watchers increases the processing time by more than a factor of four, |
|
|
982 | making it completely unusable when using larger numbers of watchers |
|
|
983 | (note that only a single file descriptor was used in the benchmark, so |
|
|
984 | inefficiencies of C<poll> do not account for this). |
|
|
985 | |
|
|
986 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
987 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
988 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
989 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
990 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
991 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
992 | above). |
|
|
993 | |
|
|
994 | C<POE>, regardless of underlying event loop (whether using its pure |
|
|
995 | perl select-based backend or the Event module, the POE-EV backend |
|
|
996 | couldn't be tested because it wasn't working) shows abysmal performance |
|
|
997 | and memory usage: Watchers use almost 30 times as much memory as |
|
|
998 | EV watchers, and 10 times as much memory as Event (the high memory |
|
|
999 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1000 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1001 | implementation. The design of the POE adaptor class in AnyEvent can not |
|
|
1002 | really account for this, as session creation overhead is small compared |
|
|
1003 | to execution of the state machine, which is coded pretty optimally within |
|
|
1004 | L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow. |
|
|
1005 | |
|
|
1006 | =head2 Summary |
|
|
1007 | |
|
|
1008 | =over 4 |
|
|
1009 | |
|
|
1010 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1011 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1012 | performance with or without AnyEvent. |
|
|
1013 | |
|
|
1014 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1015 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1016 | adds AnyEvent significant overhead. |
|
|
1017 | |
|
|
1018 | =item * You should avoid POE like the plague if you want performance or |
|
|
1019 | reasonable memory usage. |
|
|
1020 | |
|
|
1021 | =back |
|
|
1022 | |
|
|
1023 | |
|
|
1024 | =head1 FORK |
|
|
1025 | |
|
|
1026 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1027 | because they are so inefficient. Only L<EV> is fully fork-aware. |
|
|
1028 | |
|
|
1029 | If you have to fork, you must either do so I<before> creating your first |
|
|
1030 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1031 | |
|
|
1032 | |
|
|
1033 | =head1 SECURITY CONSIDERATIONS |
|
|
1034 | |
|
|
1035 | AnyEvent can be forced to load any event model via |
|
|
1036 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1037 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1038 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1039 | will not be active when the program uses a different event model than |
|
|
1040 | specified in the variable. |
|
|
1041 | |
|
|
1042 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1043 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1044 | |
|
|
1045 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1046 | |
|
|
1047 | use AnyEvent; |
|
|
1048 | |
|
|
1049 | |
319 | =head1 SEE ALSO |
1050 | =head1 SEE ALSO |
320 | |
1051 | |
321 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
1052 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
|
|
1053 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
|
|
1054 | L<Event::Lib>, L<Qt>, L<POE>. |
322 | |
1055 | |
|
|
1056 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
323 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
1057 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
|
|
1058 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
|
|
1059 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
324 | |
1060 | |
325 | Nontrivial usage example: L<Net::FCP>. |
1061 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
326 | |
1062 | |
327 | =head1 |
1063 | |
|
|
1064 | =head1 AUTHOR |
|
|
1065 | |
|
|
1066 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1067 | http://home.schmorp.de/ |
328 | |
1068 | |
329 | =cut |
1069 | =cut |
330 | |
1070 | |
331 | 1 |
1071 | 1 |
332 | |
1072 | |