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, 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 | |
20 | $w->send; # wake up current and all future recv's |
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 |
21 | $w->recv; # enters "main loop" till $condvar gets ->send |
39 | $w->broadcast; # wake up current and all future wait's |
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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. |
45 | |
70 | |
46 | =head1 DESCRIPTION |
71 | =head1 DESCRIPTION |
47 | |
72 | |
48 | L<AnyEvent> provides an identical interface to multiple event loops. This |
73 | L<AnyEvent> provides an identical interface to multiple event loops. This |
49 | allows module authors to utilizy an event loop without forcing module |
74 | 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 |
75 | users to use the same event loop (as only a single event loop can coexist |
51 | peacefully at any one time). |
76 | peacefully at any one time). |
52 | |
77 | |
53 | The interface itself is vaguely similar but not identical to the Event |
78 | The interface itself is vaguely similar, but not identical to the L<Event> |
54 | module. |
79 | module. |
55 | |
80 | |
56 | On the first call of any method, the module tries to detect the currently |
81 | During the first call of any watcher-creation method, the module tries |
57 | loaded event loop by probing wether any of the following modules is |
82 | to detect the currently loaded event loop by probing whether one of the |
58 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
83 | following modules is already loaded: L<EV>, |
59 | used. If none is found, the module tries to load these modules in the |
84 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
60 | order given. The first one that could be successfully loaded will be |
85 | L<POE>. The first one found is used. If none are found, the module tries |
61 | used. If still none could be found, it will issue an error. |
86 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
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87 | adaptor should always succeed) in the order given. The first one that can |
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88 | be successfully loaded will be used. If, after this, still none could be |
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89 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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90 | very efficient, but should work everywhere. |
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91 | |
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92 | Because AnyEvent first checks for modules that are already loaded, loading |
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93 | an event model explicitly before first using AnyEvent will likely make |
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94 | that model the default. For example: |
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95 | |
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96 | use Tk; |
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97 | use AnyEvent; |
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98 | |
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99 | # .. AnyEvent will likely default to Tk |
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100 | |
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101 | The I<likely> means that, if any module loads another event model and |
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102 | starts using it, all bets are off. Maybe you should tell their authors to |
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103 | use AnyEvent so their modules work together with others seamlessly... |
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104 | |
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105 | The pure-perl implementation of AnyEvent is called |
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106 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
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107 | explicitly. |
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108 | |
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109 | =head1 WATCHERS |
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110 | |
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111 | AnyEvent has the central concept of a I<watcher>, which is an object that |
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112 | stores relevant data for each kind of event you are waiting for, such as |
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113 | the callback to call, the filehandle to watch, etc. |
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114 | |
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115 | These watchers are normal Perl objects with normal Perl lifetime. After |
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116 | creating a watcher it will immediately "watch" for events and invoke the |
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117 | callback when the event occurs (of course, only when the event model |
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118 | is in control). |
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119 | |
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120 | To disable the watcher you have to destroy it (e.g. by setting the |
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121 | variable you store it in to C<undef> or otherwise deleting all references |
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122 | to it). |
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123 | |
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124 | All watchers are created by calling a method on the C<AnyEvent> class. |
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125 | |
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126 | Many watchers either are used with "recursion" (repeating timers for |
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127 | example), or need to refer to their watcher object in other ways. |
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128 | |
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129 | An any way to achieve that is this pattern: |
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130 | |
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131 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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132 | # you can use $w here, for example to undef it |
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133 | undef $w; |
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134 | }); |
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135 | |
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136 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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137 | my variables are only visible after the statement in which they are |
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138 | declared. |
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139 | |
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140 | =head2 I/O WATCHERS |
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141 | |
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142 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
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143 | with the following mandatory key-value pairs as arguments: |
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144 | |
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145 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch |
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146 | for events. C<poll> must be a string that is either C<r> or C<w>, |
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147 | which creates a watcher waiting for "r"eadable or "w"ritable events, |
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148 | respectively. C<cb> is the callback to invoke each time the file handle |
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149 | becomes ready. |
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150 | |
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151 | Although the callback might get passed parameters, their value and |
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152 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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153 | callbacks cannot use arguments passed to I/O watcher callbacks. |
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154 | |
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155 | The I/O watcher might use the underlying file descriptor or a copy of it. |
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156 | You must not close a file handle as long as any watcher is active on the |
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157 | underlying file descriptor. |
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158 | |
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159 | Some event loops issue spurious readyness notifications, so you should |
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160 | always use non-blocking calls when reading/writing from/to your file |
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161 | handles. |
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162 | |
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163 | Example: |
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164 | |
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165 | # wait for readability of STDIN, then read a line and disable the watcher |
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166 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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167 | chomp (my $input = <STDIN>); |
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168 | warn "read: $input\n"; |
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169 | undef $w; |
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170 | }); |
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171 | |
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172 | =head2 TIME WATCHERS |
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173 | |
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174 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
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175 | method with the following mandatory arguments: |
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176 | |
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177 | C<after> specifies after how many seconds (fractional values are |
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178 | supported) the callback should be invoked. C<cb> is the callback to invoke |
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179 | in that case. |
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180 | |
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181 | Although the callback might get passed parameters, their value and |
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182 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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183 | callbacks cannot use arguments passed to time watcher callbacks. |
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184 | |
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185 | The timer callback will be invoked at most once: if you want a repeating |
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186 | timer you have to create a new watcher (this is a limitation by both Tk |
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187 | and Glib). |
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188 | |
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189 | Example: |
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190 | |
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191 | # fire an event after 7.7 seconds |
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192 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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193 | warn "timeout\n"; |
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194 | }); |
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195 | |
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196 | # to cancel the timer: |
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197 | undef $w; |
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198 | |
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199 | Example 2: |
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200 | |
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201 | # fire an event after 0.5 seconds, then roughly every second |
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202 | my $w; |
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203 | |
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204 | my $cb = sub { |
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205 | # cancel the old timer while creating a new one |
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206 | $w = AnyEvent->timer (after => 1, cb => $cb); |
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207 | }; |
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208 | |
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209 | # start the "loop" by creating the first watcher |
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210 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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211 | |
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212 | =head3 TIMING ISSUES |
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213 | |
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214 | There are two ways to handle timers: based on real time (relative, "fire |
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215 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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216 | o'clock"). |
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217 | |
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218 | While most event loops expect timers to specified in a relative way, they |
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219 | use absolute time internally. This makes a difference when your clock |
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220 | "jumps", for example, when ntp decides to set your clock backwards from |
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221 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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222 | fire "after" a second might actually take six years to finally fire. |
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223 | |
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224 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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225 | about these issues is L<EV>, which offers both relative (ev_timer, based |
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226 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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227 | timers. |
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228 | |
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229 | AnyEvent always prefers relative timers, if available, matching the |
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230 | AnyEvent API. |
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231 | |
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232 | =head2 SIGNAL WATCHERS |
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233 | |
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234 | You can watch for signals using a signal watcher, C<signal> is the signal |
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235 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
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236 | be invoked whenever a signal occurs. |
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237 | |
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238 | Although the callback might get passed parameters, their value and |
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239 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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240 | callbacks cannot use arguments passed to signal watcher callbacks. |
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241 | |
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242 | Multiple signal occurances can be clumped together into one callback |
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243 | invocation, and callback invocation will be synchronous. synchronous means |
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244 | that it might take a while until the signal gets handled by the process, |
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245 | but it is guarenteed not to interrupt any other callbacks. |
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246 | |
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247 | The main advantage of using these watchers is that you can share a signal |
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248 | between multiple watchers. |
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249 | |
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250 | This watcher might use C<%SIG>, so programs overwriting those signals |
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251 | directly will likely not work correctly. |
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252 | |
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253 | Example: exit on SIGINT |
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254 | |
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255 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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256 | |
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257 | =head2 CHILD PROCESS WATCHERS |
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258 | |
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259 | You can also watch on a child process exit and catch its exit status. |
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260 | |
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261 | The child process is specified by the C<pid> argument (if set to C<0>, it |
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262 | watches for any child process exit). The watcher will trigger as often |
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263 | as status change for the child are received. This works by installing a |
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264 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
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265 | and exit status (as returned by waitpid), so unlike other watcher types, |
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266 | you I<can> rely on child watcher callback arguments. |
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267 | |
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268 | There is a slight catch to child watchers, however: you usually start them |
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269 | I<after> the child process was created, and this means the process could |
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270 | have exited already (and no SIGCHLD will be sent anymore). |
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271 | |
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272 | Not all event models handle this correctly (POE doesn't), but even for |
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273 | event models that I<do> handle this correctly, they usually need to be |
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274 | loaded before the process exits (i.e. before you fork in the first place). |
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275 | |
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276 | This means you cannot create a child watcher as the very first thing in an |
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277 | AnyEvent program, you I<have> to create at least one watcher before you |
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278 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
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279 | |
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280 | Example: fork a process and wait for it |
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281 | |
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282 | my $done = AnyEvent->condvar; |
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283 | |
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284 | my $pid = fork or exit 5; |
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285 | |
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286 | my $w = AnyEvent->child ( |
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287 | pid => $pid, |
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288 | cb => sub { |
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289 | my ($pid, $status) = @_; |
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290 | warn "pid $pid exited with status $status"; |
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291 | $done->send; |
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292 | }, |
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293 | ); |
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294 | |
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295 | # do something else, then wait for process exit |
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296 | $done->recv; |
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297 | |
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298 | =head2 CONDITION VARIABLES |
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299 | |
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300 | If you are familiar with some event loops you will know that all of them |
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301 | require you to run some blocking "loop", "run" or similar function that |
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302 | will actively watch for new events and call your callbacks. |
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303 | |
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304 | AnyEvent is different, it expects somebody else to run the event loop and |
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305 | will only block when necessary (usually when told by the user). |
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306 | |
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307 | The instrument to do that is called a "condition variable", so called |
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308 | because they represent a condition that must become true. |
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309 | |
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310 | Condition variables can be created by calling the C<< AnyEvent->condvar |
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311 | >> method, usually without arguments. The only argument pair allowed is |
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312 | C<cb>, which specifies a callback to be called when the condition variable |
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313 | becomes true. |
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314 | |
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315 | After creation, the conditon variable is "false" until it becomes "true" |
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316 | by calling the C<send> method. |
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317 | |
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318 | Condition variables are similar to callbacks, except that you can |
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319 | optionally wait for them. They can also be called merge points - points |
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320 | in time where multiple outstandign events have been processed. And yet |
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321 | another way to call them is transations - each condition variable can be |
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322 | used to represent a transaction, which finishes at some point and delivers |
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323 | a result. |
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324 | |
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325 | Condition variables are very useful to signal that something has finished, |
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326 | for example, if you write a module that does asynchronous http requests, |
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327 | then a condition variable would be the ideal candidate to signal the |
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328 | availability of results. The user can either act when the callback is |
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329 | called or can synchronously C<< ->recv >> for the results. |
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330 | |
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331 | You can also use them to simulate traditional event loops - for example, |
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332 | you can block your main program until an event occurs - for example, you |
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333 | could C<< ->recv >> in your main program until the user clicks the Quit |
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334 | button of your app, which would C<< ->send >> the "quit" event. |
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335 | |
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336 | Note that condition variables recurse into the event loop - if you have |
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337 | two pieces of code that call C<< ->recv >> in a round-robbin fashion, you |
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338 | lose. Therefore, condition variables are good to export to your caller, but |
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339 | you should avoid making a blocking wait yourself, at least in callbacks, |
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340 | as this asks for trouble. |
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341 | |
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342 | Condition variables are represented by hash refs in perl, and the keys |
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343 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
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344 | easy (it is often useful to build your own transaction class on top of |
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345 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
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346 | it's C<new> method in your own C<new> method. |
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347 | |
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348 | There are two "sides" to a condition variable - the "producer side" which |
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349 | eventually calls C<< -> send >>, and the "consumer side", which waits |
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350 | for the send to occur. |
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351 | |
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352 | Example: |
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353 | |
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354 | # wait till the result is ready |
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355 | my $result_ready = AnyEvent->condvar; |
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356 | |
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357 | # do something such as adding a timer |
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358 | # or socket watcher the calls $result_ready->send |
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359 | # when the "result" is ready. |
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360 | # in this case, we simply use a timer: |
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361 | my $w = AnyEvent->timer ( |
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362 | after => 1, |
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363 | cb => sub { $result_ready->send }, |
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364 | ); |
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365 | |
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366 | # this "blocks" (while handling events) till the callback |
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367 | # calls send |
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368 | $result_ready->recv; |
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369 | |
|
|
370 | =head3 METHODS FOR PRODUCERS |
|
|
371 | |
|
|
372 | These methods should only be used by the producing side, i.e. the |
|
|
373 | code/module that eventually sends the signal. Note that it is also |
|
|
374 | the producer side which creates the condvar in most cases, but it isn't |
|
|
375 | uncommon for the consumer to create it as well. |
62 | |
376 | |
63 | =over 4 |
377 | =over 4 |
64 | |
378 | |
|
|
379 | =item $cv->send (...) |
|
|
380 | |
|
|
381 | Flag the condition as ready - a running C<< ->recv >> and all further |
|
|
382 | calls to C<recv> will (eventually) return after this method has been |
|
|
383 | called. If nobody is waiting the send will be remembered. |
|
|
384 | |
|
|
385 | If a callback has been set on the condition variable, it is called |
|
|
386 | immediately from within send. |
|
|
387 | |
|
|
388 | Any arguments passed to the C<send> call will be returned by all |
|
|
389 | future C<< ->recv >> calls. |
|
|
390 | |
|
|
391 | =item $cv->croak ($error) |
|
|
392 | |
|
|
393 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
|
|
394 | C<Carp::croak> with the given error message/object/scalar. |
|
|
395 | |
|
|
396 | This can be used to signal any errors to the condition variable |
|
|
397 | user/consumer. |
|
|
398 | |
|
|
399 | =item $cv->begin ([group callback]) |
|
|
400 | |
|
|
401 | =item $cv->end |
|
|
402 | |
|
|
403 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
404 | |
|
|
405 | These two methods can be used to combine many transactions/events into |
|
|
406 | one. For example, a function that pings many hosts in parallel might want |
|
|
407 | to use a condition variable for the whole process. |
|
|
408 | |
|
|
409 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
410 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
411 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
412 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
413 | callback was set, C<send> will be called without any arguments. |
|
|
414 | |
|
|
415 | Let's clarify this with the ping example: |
|
|
416 | |
|
|
417 | my $cv = AnyEvent->condvar; |
|
|
418 | |
|
|
419 | my %result; |
|
|
420 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
421 | |
|
|
422 | for my $host (@list_of_hosts) { |
|
|
423 | $cv->begin; |
|
|
424 | ping_host_then_call_callback $host, sub { |
|
|
425 | $result{$host} = ...; |
|
|
426 | $cv->end; |
|
|
427 | }; |
|
|
428 | } |
|
|
429 | |
|
|
430 | $cv->end; |
|
|
431 | |
|
|
432 | This code fragment supposedly pings a number of hosts and calls |
|
|
433 | C<send> after results for all then have have been gathered - in any |
|
|
434 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
435 | each ping request and calls C<end> when it has received some result for |
|
|
436 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
437 | results arrive is not relevant. |
|
|
438 | |
|
|
439 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
440 | loop, which serves two important purposes: first, it sets the callback |
|
|
441 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
442 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
443 | doesn't execute once). |
|
|
444 | |
|
|
445 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
446 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
447 | is called at least once, and then, for each subrequest you start, call |
|
|
448 | C<begin> and for eahc subrequest you finish, call C<end>. |
|
|
449 | |
|
|
450 | =back |
|
|
451 | |
|
|
452 | =head3 METHODS FOR CONSUMERS |
|
|
453 | |
|
|
454 | These methods should only be used by the consuming side, i.e. the |
|
|
455 | code awaits the condition. |
|
|
456 | |
|
|
457 | =over 4 |
|
|
458 | |
|
|
459 | =item $cv->recv |
|
|
460 | |
|
|
461 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
|
|
462 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
463 | normally. |
|
|
464 | |
|
|
465 | You can only wait once on a condition - additional calls are valid but |
|
|
466 | will return immediately. |
|
|
467 | |
|
|
468 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
469 | function will call C<croak>. |
|
|
470 | |
|
|
471 | In list context, all parameters passed to C<send> will be returned, |
|
|
472 | in scalar context only the first one will be returned. |
|
|
473 | |
|
|
474 | Not all event models support a blocking wait - some die in that case |
|
|
475 | (programs might want to do that to stay interactive), so I<if you are |
|
|
476 | using this from a module, never require a blocking wait>, but let the |
|
|
477 | caller decide whether the call will block or not (for example, by coupling |
|
|
478 | condition variables with some kind of request results and supporting |
|
|
479 | callbacks so the caller knows that getting the result will not block, |
|
|
480 | while still suppporting blocking waits if the caller so desires). |
|
|
481 | |
|
|
482 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
|
|
483 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
|
|
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
|
|
485 | can supply. |
|
|
486 | |
|
|
487 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
488 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
489 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
490 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
491 | coroutine (one that doesn't run the event loop). |
|
|
492 | |
|
|
493 | You can ensure that C<< -recv >> never blocks by setting a callback and |
|
|
494 | only calling C<< ->recv >> from within that callback (or at a later |
|
|
495 | time). This will work even when the event loop does not support blocking |
|
|
496 | waits otherwise. |
|
|
497 | |
|
|
498 | =item $bool = $cv->ready |
|
|
499 | |
|
|
500 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
501 | C<croak> have been called. |
|
|
502 | |
|
|
503 | =item $cb = $cv->cb ([new callback]) |
|
|
504 | |
|
|
505 | This is a mutator function that returns the callback set and optionally |
|
|
506 | replaces it before doing so. |
|
|
507 | |
|
|
508 | The callback will be called when the condition becomes "true", i.e. when |
|
|
509 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
|
|
510 | or at any later time is guaranteed not to block. |
|
|
511 | |
|
|
512 | =back |
|
|
513 | |
|
|
514 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
|
|
515 | |
|
|
516 | =over 4 |
|
|
517 | |
|
|
518 | =item $AnyEvent::MODEL |
|
|
519 | |
|
|
520 | Contains C<undef> until the first watcher is being created. Then it |
|
|
521 | contains the event model that is being used, which is the name of the |
|
|
522 | Perl class implementing the model. This class is usually one of the |
|
|
523 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
|
|
524 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
|
|
525 | |
|
|
526 | The known classes so far are: |
|
|
527 | |
|
|
528 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
|
|
529 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
530 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
531 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
532 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
|
|
533 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
534 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
535 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
536 | |
|
|
537 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
538 | watching file handles. However, you can use WxWidgets through the |
|
|
539 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
540 | second, which was considered to be too horrible to even consider for |
|
|
541 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
542 | it's adaptor. |
|
|
543 | |
|
|
544 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
545 | autodetecting them. |
|
|
546 | |
|
|
547 | =item AnyEvent::detect |
|
|
548 | |
|
|
549 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
|
|
550 | if necessary. You should only call this function right before you would |
|
|
551 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
552 | runtime. |
|
|
553 | |
|
|
554 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
555 | |
|
|
556 | Arranges for the code block to be executed as soon as the event model is |
|
|
557 | autodetected (or immediately if this has already happened). |
|
|
558 | |
|
|
559 | If called in scalar or list context, then it creates and returns an object |
|
|
560 | that automatically removes the callback again when it is destroyed. See |
|
|
561 | L<Coro::BDB> for a case where this is useful. |
|
|
562 | |
|
|
563 | =item @AnyEvent::post_detect |
|
|
564 | |
|
|
565 | If there are any code references in this array (you can C<push> to it |
|
|
566 | before or after loading AnyEvent), then they will called directly after |
|
|
567 | the event loop has been chosen. |
|
|
568 | |
|
|
569 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
570 | if it contains a true value then the event loop has already been detected, |
|
|
571 | and the array will be ignored. |
|
|
572 | |
|
|
573 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
|
|
574 | |
|
|
575 | =back |
|
|
576 | |
|
|
577 | =head1 WHAT TO DO IN A MODULE |
|
|
578 | |
|
|
579 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
|
|
580 | freely, but you should not load a specific event module or rely on it. |
|
|
581 | |
|
|
582 | Be careful when you create watchers in the module body - AnyEvent will |
|
|
583 | decide which event module to use as soon as the first method is called, so |
|
|
584 | by calling AnyEvent in your module body you force the user of your module |
|
|
585 | to load the event module first. |
|
|
586 | |
|
|
587 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
|
|
588 | the C<< ->send >> method has been called on it already. This is |
|
|
589 | because it will stall the whole program, and the whole point of using |
|
|
590 | events is to stay interactive. |
|
|
591 | |
|
|
592 | It is fine, however, to call C<< ->recv >> when the user of your module |
|
|
593 | requests it (i.e. if you create a http request object ad have a method |
|
|
594 | called C<results> that returns the results, it should call C<< ->recv >> |
|
|
595 | freely, as the user of your module knows what she is doing. always). |
|
|
596 | |
|
|
597 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
|
|
598 | |
|
|
599 | There will always be a single main program - the only place that should |
|
|
600 | dictate which event model to use. |
|
|
601 | |
|
|
602 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
|
|
603 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
604 | decide which implementation to chose if some module relies on it. |
|
|
605 | |
|
|
606 | If the main program relies on a specific event model. For example, in |
|
|
607 | Gtk2 programs you have to rely on the Glib module. You should load the |
|
|
608 | event module before loading AnyEvent or any module that uses it: generally |
|
|
609 | speaking, you should load it as early as possible. The reason is that |
|
|
610 | modules might create watchers when they are loaded, and AnyEvent will |
|
|
611 | decide on the event model to use as soon as it creates watchers, and it |
|
|
612 | might chose the wrong one unless you load the correct one yourself. |
|
|
613 | |
|
|
614 | You can chose to use a rather inefficient pure-perl implementation by |
|
|
615 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
|
|
616 | behaviour everywhere, but letting AnyEvent chose is generally better. |
|
|
617 | |
|
|
618 | =head1 OTHER MODULES |
|
|
619 | |
|
|
620 | The following is a non-exhaustive list of additional modules that use |
|
|
621 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
622 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
623 | available via CPAN. |
|
|
624 | |
|
|
625 | =over 4 |
|
|
626 | |
|
|
627 | =item L<AnyEvent::Util> |
|
|
628 | |
|
|
629 | Contains various utility functions that replace often-used but blocking |
|
|
630 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
631 | |
|
|
632 | =item L<AnyEvent::Handle> |
|
|
633 | |
|
|
634 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
635 | |
|
|
636 | =item L<AnyEvent::Socket> |
|
|
637 | |
|
|
638 | Provides various utility functions for (internet protocol) sockets, |
|
|
639 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
640 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
641 | |
|
|
642 | =item L<AnyEvent::HTTPD> |
|
|
643 | |
|
|
644 | Provides a simple web application server framework. |
|
|
645 | |
|
|
646 | =item L<AnyEvent::DNS> |
|
|
647 | |
|
|
648 | Provides rich asynchronous DNS resolver capabilities. |
|
|
649 | |
|
|
650 | =item L<AnyEvent::FastPing> |
|
|
651 | |
|
|
652 | The fastest ping in the west. |
|
|
653 | |
|
|
654 | =item L<Net::IRC3> |
|
|
655 | |
|
|
656 | AnyEvent based IRC client module family. |
|
|
657 | |
|
|
658 | =item L<Net::XMPP2> |
|
|
659 | |
|
|
660 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
661 | |
|
|
662 | =item L<Net::FCP> |
|
|
663 | |
|
|
664 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
665 | of AnyEvent. |
|
|
666 | |
|
|
667 | =item L<Event::ExecFlow> |
|
|
668 | |
|
|
669 | High level API for event-based execution flow control. |
|
|
670 | |
|
|
671 | =item L<Coro> |
|
|
672 | |
|
|
673 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
674 | |
|
|
675 | =item L<AnyEvent::AIO>, L<IO::AIO> |
|
|
676 | |
|
|
677 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
678 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
679 | together. |
|
|
680 | |
|
|
681 | =item L<AnyEvent::BDB>, L<BDB> |
|
|
682 | |
|
|
683 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses |
|
|
684 | IO::AIO and AnyEvent together. |
|
|
685 | |
|
|
686 | =item L<IO::Lambda> |
|
|
687 | |
|
|
688 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
689 | |
|
|
690 | =back |
|
|
691 | |
65 | =cut |
692 | =cut |
66 | |
693 | |
67 | package AnyEvent; |
694 | package AnyEvent; |
68 | |
695 | |
69 | no warnings; |
696 | no warnings; |
70 | use strict 'vars'; |
697 | use strict; |
|
|
698 | |
71 | use Carp; |
699 | use Carp; |
72 | |
700 | |
73 | our $VERSION = '1.02'; |
701 | our $VERSION = '3.6'; |
74 | our $MODEL; |
702 | our $MODEL; |
75 | |
703 | |
76 | our $AUTOLOAD; |
704 | our $AUTOLOAD; |
77 | our @ISA; |
705 | our @ISA; |
78 | |
706 | |
79 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
707 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
80 | |
708 | |
81 | our @REGISTRY; |
709 | our @REGISTRY; |
82 | |
710 | |
|
|
711 | our %PROTOCOL; # (ipv4|ipv6) => (1|2) |
|
|
712 | |
|
|
713 | { |
|
|
714 | my $idx; |
|
|
715 | $PROTOCOL{$_} = ++$idx |
|
|
716 | for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
717 | } |
|
|
718 | |
83 | my @models = ( |
719 | my @models = ( |
84 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
720 | [EV:: => AnyEvent::Impl::EV::], |
85 | [Event:: => AnyEvent::Impl::Event::], |
721 | [Event:: => AnyEvent::Impl::Event::], |
|
|
722 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
723 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
724 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
725 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
726 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
86 | [Glib:: => AnyEvent::Impl::Glib::], |
727 | [Glib:: => AnyEvent::Impl::Glib::], |
87 | [Tk:: => AnyEvent::Impl::Tk::], |
728 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
729 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
730 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
88 | ); |
731 | ); |
89 | |
732 | |
90 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY); |
733 | our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); |
91 | |
734 | |
92 | sub AUTOLOAD { |
735 | our @post_detect; |
93 | $AUTOLOAD =~ s/.*://; |
|
|
94 | |
736 | |
95 | $method{$AUTOLOAD} |
737 | sub post_detect(&) { |
96 | or croak "$AUTOLOAD: not a valid method for AnyEvent objects"; |
738 | my ($cb) = @_; |
97 | |
739 | |
|
|
740 | if ($MODEL) { |
|
|
741 | $cb->(); |
|
|
742 | |
|
|
743 | 1 |
|
|
744 | } else { |
|
|
745 | push @post_detect, $cb; |
|
|
746 | |
|
|
747 | defined wantarray |
|
|
748 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
749 | : () |
|
|
750 | } |
|
|
751 | } |
|
|
752 | |
|
|
753 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
754 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
755 | } |
|
|
756 | |
|
|
757 | sub detect() { |
98 | unless ($MODEL) { |
758 | unless ($MODEL) { |
|
|
759 | no strict 'refs'; |
|
|
760 | |
|
|
761 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
762 | my $model = "AnyEvent::Impl::$1"; |
|
|
763 | if (eval "require $model") { |
|
|
764 | $MODEL = $model; |
|
|
765 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
766 | } else { |
|
|
767 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
768 | } |
|
|
769 | } |
|
|
770 | |
99 | # check for already loaded models |
771 | # check for already loaded models |
|
|
772 | unless ($MODEL) { |
100 | for (@REGISTRY, @models) { |
773 | for (@REGISTRY, @models) { |
101 | my ($package, $model) = @$_; |
774 | my ($package, $model) = @$_; |
102 | if (${"$package\::VERSION"} > 0) { |
775 | if (${"$package\::VERSION"} > 0) { |
103 | if (eval "require $model") { |
776 | if (eval "require $model") { |
104 | $MODEL = $model; |
777 | $MODEL = $model; |
105 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
778 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
106 | last; |
779 | last; |
|
|
780 | } |
107 | } |
781 | } |
108 | } |
782 | } |
|
|
783 | |
|
|
784 | unless ($MODEL) { |
|
|
785 | # try to load a model |
|
|
786 | |
|
|
787 | for (@REGISTRY, @models) { |
|
|
788 | my ($package, $model) = @$_; |
|
|
789 | if (eval "require $package" |
|
|
790 | and ${"$package\::VERSION"} > 0 |
|
|
791 | and eval "require $model") { |
|
|
792 | $MODEL = $model; |
|
|
793 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
|
|
794 | last; |
|
|
795 | } |
|
|
796 | } |
|
|
797 | |
|
|
798 | $MODEL |
|
|
799 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
|
|
800 | } |
109 | } |
801 | } |
110 | |
802 | |
111 | unless ($MODEL) { |
803 | unshift @ISA, $MODEL; |
112 | # try to load a model |
804 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
113 | |
805 | |
114 | for (@REGISTRY, @models) { |
806 | (shift @post_detect)->() while @post_detect; |
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 | } |
807 | } |
127 | |
808 | |
128 | @ISA = $MODEL; |
809 | $MODEL |
|
|
810 | } |
|
|
811 | |
|
|
812 | sub AUTOLOAD { |
|
|
813 | (my $func = $AUTOLOAD) =~ s/.*://; |
|
|
814 | |
|
|
815 | $method{$func} |
|
|
816 | or croak "$func: not a valid method for AnyEvent objects"; |
|
|
817 | |
|
|
818 | detect unless $MODEL; |
129 | |
819 | |
130 | my $class = shift; |
820 | my $class = shift; |
131 | $class->$AUTOLOAD (@_); |
821 | $class->$func (@_); |
132 | } |
822 | } |
133 | |
823 | |
134 | =back |
824 | package AnyEvent::Base; |
|
|
825 | |
|
|
826 | # default implementation for ->condvar |
|
|
827 | |
|
|
828 | sub condvar { |
|
|
829 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
|
|
830 | } |
|
|
831 | |
|
|
832 | # default implementation for ->signal |
|
|
833 | |
|
|
834 | our %SIG_CB; |
|
|
835 | |
|
|
836 | sub signal { |
|
|
837 | my (undef, %arg) = @_; |
|
|
838 | |
|
|
839 | my $signal = uc $arg{signal} |
|
|
840 | or Carp::croak "required option 'signal' is missing"; |
|
|
841 | |
|
|
842 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
|
|
843 | $SIG{$signal} ||= sub { |
|
|
844 | $_->() for values %{ $SIG_CB{$signal} || {} }; |
|
|
845 | }; |
|
|
846 | |
|
|
847 | bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
|
|
848 | } |
|
|
849 | |
|
|
850 | sub AnyEvent::Base::Signal::DESTROY { |
|
|
851 | my ($signal, $cb) = @{$_[0]}; |
|
|
852 | |
|
|
853 | delete $SIG_CB{$signal}{$cb}; |
|
|
854 | |
|
|
855 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
|
|
856 | } |
|
|
857 | |
|
|
858 | # default implementation for ->child |
|
|
859 | |
|
|
860 | our %PID_CB; |
|
|
861 | our $CHLD_W; |
|
|
862 | our $CHLD_DELAY_W; |
|
|
863 | our $PID_IDLE; |
|
|
864 | our $WNOHANG; |
|
|
865 | |
|
|
866 | sub _child_wait { |
|
|
867 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
|
|
868 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
|
|
869 | (values %{ $PID_CB{0} || {} }); |
|
|
870 | } |
|
|
871 | |
|
|
872 | undef $PID_IDLE; |
|
|
873 | } |
|
|
874 | |
|
|
875 | sub _sigchld { |
|
|
876 | # make sure we deliver these changes "synchronous" with the event loop. |
|
|
877 | $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
|
|
878 | undef $CHLD_DELAY_W; |
|
|
879 | &_child_wait; |
|
|
880 | }); |
|
|
881 | } |
|
|
882 | |
|
|
883 | sub child { |
|
|
884 | my (undef, %arg) = @_; |
|
|
885 | |
|
|
886 | defined (my $pid = $arg{pid} + 0) |
|
|
887 | or Carp::croak "required option 'pid' is missing"; |
|
|
888 | |
|
|
889 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
|
|
890 | |
|
|
891 | unless ($WNOHANG) { |
|
|
892 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
|
|
893 | } |
|
|
894 | |
|
|
895 | unless ($CHLD_W) { |
|
|
896 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
|
|
897 | # child could be a zombie already, so make at least one round |
|
|
898 | &_sigchld; |
|
|
899 | } |
|
|
900 | |
|
|
901 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
|
|
902 | } |
|
|
903 | |
|
|
904 | sub AnyEvent::Base::Child::DESTROY { |
|
|
905 | my ($pid, $cb) = @{$_[0]}; |
|
|
906 | |
|
|
907 | delete $PID_CB{$pid}{$cb}; |
|
|
908 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
|
|
909 | |
|
|
910 | undef $CHLD_W unless keys %PID_CB; |
|
|
911 | } |
|
|
912 | |
|
|
913 | package AnyEvent::CondVar; |
|
|
914 | |
|
|
915 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
916 | |
|
|
917 | package AnyEvent::CondVar::Base; |
|
|
918 | |
|
|
919 | sub _send { |
|
|
920 | # nop |
|
|
921 | } |
|
|
922 | |
|
|
923 | sub send { |
|
|
924 | my $cv = shift; |
|
|
925 | $cv->{_ae_sent} = [@_]; |
|
|
926 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
927 | $cv->_send; |
|
|
928 | } |
|
|
929 | |
|
|
930 | sub croak { |
|
|
931 | $_[0]{_ae_croak} = $_[1]; |
|
|
932 | $_[0]->send; |
|
|
933 | } |
|
|
934 | |
|
|
935 | sub ready { |
|
|
936 | $_[0]{_ae_sent} |
|
|
937 | } |
|
|
938 | |
|
|
939 | sub _wait { |
|
|
940 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
941 | } |
|
|
942 | |
|
|
943 | sub recv { |
|
|
944 | $_[0]->_wait; |
|
|
945 | |
|
|
946 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
947 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
948 | } |
|
|
949 | |
|
|
950 | sub cb { |
|
|
951 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
952 | $_[0]{_ae_cb} |
|
|
953 | } |
|
|
954 | |
|
|
955 | sub begin { |
|
|
956 | ++$_[0]{_ae_counter}; |
|
|
957 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
958 | } |
|
|
959 | |
|
|
960 | sub end { |
|
|
961 | return if --$_[0]{_ae_counter}; |
|
|
962 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
963 | } |
|
|
964 | |
|
|
965 | # undocumented/compatibility with pre-3.4 |
|
|
966 | *broadcast = \&send; |
|
|
967 | *wait = \&_wait; |
135 | |
968 | |
136 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
969 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
970 | |
|
|
971 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
972 | a module. This section is only of use to event loop authors who want to |
|
|
973 | provide AnyEvent compatibility. |
137 | |
974 | |
138 | If you need to support another event library which isn't directly |
975 | 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 |
976 | supported by AnyEvent, you can supply your own interface to it by |
140 | pushing, before the first watcher gets created, the package name of |
977 | 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 |
978 | 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 |
979 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
143 | AnyEvent. |
980 | AnyEvent, so it is reasonably cheap. |
144 | |
981 | |
145 | Example: |
982 | Example: |
146 | |
983 | |
147 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
984 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
148 | |
985 | |
149 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
986 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
150 | package/class when it finds the C<urxvt> package/module is loaded. When |
987 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
988 | |
151 | AnyEvent is loaded and asked to find a suitable event model, it will |
989 | When AnyEvent is loaded and asked to find a suitable event model, it |
152 | first check for the presence of urxvt. |
990 | will first check for the presence of urxvt by trying to C<use> the |
|
|
991 | C<urxvt::anyevent> module. |
153 | |
992 | |
154 | The class should prove implementations for all watcher types (see |
993 | The class should provide implementations for all watcher types. See |
155 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
994 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
156 | (Source code) and so on for actual examples, use C<perldoc -m |
995 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
157 | AnyEvent::Impl::Glib> to see the sources). |
996 | see the sources. |
158 | |
997 | |
|
|
998 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
999 | provide suitable (hopefully) replacements. |
|
|
1000 | |
159 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
1001 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
160 | uses the above line as-is. An interface isn't included in AnyEvent |
1002 | terminal emulator uses the above line as-is. An interface isn't included |
161 | because it doesn't make sense outside the embedded interpreter inside |
1003 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
162 | I<rxvt-unicode>, and it is updated and maintained as part of the |
1004 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
163 | I<rxvt-unicode> distribution. |
1005 | I<rxvt-unicode> distribution. |
164 | |
1006 | |
165 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
1007 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
166 | condition variables: code blocking while waiting for a condition will |
1008 | condition variables: code blocking while waiting for a condition will |
167 | C<die>. This still works with most modules/usages, and blocking calls must |
1009 | C<die>. This still works with most modules/usages, and blocking calls must |
168 | not be in an interactive appliation, so it makes sense. |
1010 | not be done in an interactive application, so it makes sense. |
169 | |
1011 | |
170 | =head1 ENVIRONMENT VARIABLES |
1012 | =head1 ENVIRONMENT VARIABLES |
171 | |
1013 | |
172 | The following environment variables are used by this module: |
1014 | The following environment variables are used by this module: |
173 | |
1015 | |
174 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
1016 | =over 4 |
175 | model gets used. |
|
|
176 | |
1017 | |
|
|
1018 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1019 | |
|
|
1020 | By default, AnyEvent will be completely silent except in fatal |
|
|
1021 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1022 | talkative. |
|
|
1023 | |
|
|
1024 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1025 | conditions, such as not being able to load the event model specified by |
|
|
1026 | C<PERL_ANYEVENT_MODEL>. |
|
|
1027 | |
|
|
1028 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1029 | model it chooses. |
|
|
1030 | |
|
|
1031 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1032 | |
|
|
1033 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1034 | autodetection and -probing kicks in. It must be a string consisting |
|
|
1035 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1036 | and the resulting module name is loaded and if the load was successful, |
|
|
1037 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1038 | autodetection and -probing. |
|
|
1039 | |
|
|
1040 | This functionality might change in future versions. |
|
|
1041 | |
|
|
1042 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1043 | could start your program like this: |
|
|
1044 | |
|
|
1045 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1046 | |
|
|
1047 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1048 | |
|
|
1049 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1050 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1051 | of autoprobing). |
|
|
1052 | |
|
|
1053 | Must be set to a comma-separated list of protocols or address families, |
|
|
1054 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1055 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1056 | list. |
|
|
1057 | |
|
|
1058 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1059 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1060 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1061 | addressses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1062 | IPv6, but prefer IPv6 over IPv4. |
|
|
1063 | |
|
|
1064 | =back |
|
|
1065 | |
177 | =head1 EXAMPLE |
1066 | =head1 EXAMPLE PROGRAM |
178 | |
1067 | |
179 | The following program uses an io watcher to read data from stdin, a timer |
1068 | The following program uses an I/O watcher to read data from STDIN, a timer |
180 | to display a message once per second, and a condvar to exit the program |
1069 | to display a message once per second, and a condition variable to quit the |
181 | when the user enters quit: |
1070 | program when the user enters quit: |
182 | |
1071 | |
183 | use AnyEvent; |
1072 | use AnyEvent; |
184 | |
1073 | |
185 | my $cv = AnyEvent->condvar; |
1074 | my $cv = AnyEvent->condvar; |
186 | |
1075 | |
187 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
1076 | my $io_watcher = AnyEvent->io ( |
|
|
1077 | fh => \*STDIN, |
|
|
1078 | poll => 'r', |
|
|
1079 | cb => sub { |
188 | warn "io event <$_[0]>\n"; # will always output <r> |
1080 | warn "io event <$_[0]>\n"; # will always output <r> |
189 | chomp (my $input = <STDIN>); # read a line |
1081 | chomp (my $input = <STDIN>); # read a line |
190 | warn "read: $input\n"; # output what has been read |
1082 | warn "read: $input\n"; # output what has been read |
191 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1083 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
|
|
1084 | }, |
192 | }); |
1085 | ); |
193 | |
1086 | |
194 | my $time_watcher; # can only be used once |
1087 | my $time_watcher; # can only be used once |
195 | |
1088 | |
196 | sub new_timer { |
1089 | sub new_timer { |
197 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1090 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
200 | }); |
1093 | }); |
201 | } |
1094 | } |
202 | |
1095 | |
203 | new_timer; # create first timer |
1096 | new_timer; # create first timer |
204 | |
1097 | |
205 | $cv->wait; # wait until user enters /^q/i |
1098 | $cv->recv; # wait until user enters /^q/i |
206 | |
1099 | |
207 | =head1 REAL-WORLD EXAMPLE |
1100 | =head1 REAL-WORLD EXAMPLE |
208 | |
1101 | |
209 | Consider the L<Net::FCP> module. It features (among others) the following |
1102 | Consider the L<Net::FCP> module. It features (among others) the following |
210 | API calls, which are to freenet what HTTP GET requests are to http: |
1103 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
266 | |
1159 | |
267 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1160 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
268 | |
1161 | |
269 | if (end-of-file or data complete) { |
1162 | if (end-of-file or data complete) { |
270 | $txn->{result} = $txn->{buf}; |
1163 | $txn->{result} = $txn->{buf}; |
271 | $txn->{finished}->broadcast; |
1164 | $txn->{finished}->send; |
272 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1165 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
273 | } |
1166 | } |
274 | |
1167 | |
275 | The C<result> method, finally, just waits for the finished signal (if the |
1168 | The C<result> method, finally, just waits for the finished signal (if the |
276 | request was already finished, it doesn't wait, of course, and returns the |
1169 | request was already finished, it doesn't wait, of course, and returns the |
277 | data: |
1170 | data: |
278 | |
1171 | |
279 | $txn->{finished}->wait; |
1172 | $txn->{finished}->recv; |
280 | return $txn->{result}; |
1173 | return $txn->{result}; |
281 | |
1174 | |
282 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1175 | The actual code goes further and collects all errors (C<die>s, exceptions) |
283 | that occured during request processing. The C<result> method detects |
1176 | that occured during request processing. The C<result> method detects |
284 | wether an exception as thrown (it is stored inside the $txn object) |
1177 | whether an exception as thrown (it is stored inside the $txn object) |
285 | and just throws the exception, which means connection errors and other |
1178 | and just throws the exception, which means connection errors and other |
286 | problems get reported tot he code that tries to use the result, not in a |
1179 | problems get reported tot he code that tries to use the result, not in a |
287 | random callback. |
1180 | random callback. |
288 | |
1181 | |
289 | All of this enables the following usage styles: |
1182 | All of this enables the following usage styles: |
290 | |
1183 | |
291 | 1. Blocking: |
1184 | 1. Blocking: |
292 | |
1185 | |
293 | my $data = $fcp->client_get ($url); |
1186 | my $data = $fcp->client_get ($url); |
294 | |
1187 | |
295 | 2. Blocking, but parallelizing: |
1188 | 2. Blocking, but running in parallel: |
296 | |
1189 | |
297 | my @datas = map $_->result, |
1190 | my @datas = map $_->result, |
298 | map $fcp->txn_client_get ($_), |
1191 | map $fcp->txn_client_get ($_), |
299 | @urls; |
1192 | @urls; |
300 | |
1193 | |
301 | Both blocking examples work without the module user having to know |
1194 | Both blocking examples work without the module user having to know |
302 | anything about events. |
1195 | anything about events. |
303 | |
1196 | |
304 | 3a. Event-based in a main program, using any support Event module: |
1197 | 3a. Event-based in a main program, using any supported event module: |
305 | |
1198 | |
306 | use Event; |
1199 | use EV; |
307 | |
1200 | |
308 | $fcp->txn_client_get ($url)->cb (sub { |
1201 | $fcp->txn_client_get ($url)->cb (sub { |
309 | my $txn = shift; |
1202 | my $txn = shift; |
310 | my $data = $txn->result; |
1203 | my $data = $txn->result; |
311 | ... |
1204 | ... |
312 | }); |
1205 | }); |
313 | |
1206 | |
314 | Event::loop; |
1207 | EV::loop; |
315 | |
1208 | |
316 | 3b. The module user could use AnyEvent, too: |
1209 | 3b. The module user could use AnyEvent, too: |
317 | |
1210 | |
318 | use AnyEvent; |
1211 | use AnyEvent; |
319 | |
1212 | |
320 | my $quit = AnyEvent->condvar; |
1213 | my $quit = AnyEvent->condvar; |
321 | |
1214 | |
322 | $fcp->txn_client_get ($url)->cb (sub { |
1215 | $fcp->txn_client_get ($url)->cb (sub { |
323 | ... |
1216 | ... |
324 | $quit->broadcast; |
1217 | $quit->send; |
325 | }); |
1218 | }); |
326 | |
1219 | |
327 | $quit->wait; |
1220 | $quit->recv; |
|
|
1221 | |
|
|
1222 | |
|
|
1223 | =head1 BENCHMARKS |
|
|
1224 | |
|
|
1225 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1226 | over the event loops themselves and to give you an impression of the speed |
|
|
1227 | of various event loops I prepared some benchmarks. |
|
|
1228 | |
|
|
1229 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1230 | |
|
|
1231 | Here is a benchmark of various supported event models used natively and |
|
|
1232 | through anyevent. The benchmark creates a lot of timers (with a zero |
|
|
1233 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1234 | which it is), lets them fire exactly once and destroys them again. |
|
|
1235 | |
|
|
1236 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1237 | distribution. |
|
|
1238 | |
|
|
1239 | =head3 Explanation of the columns |
|
|
1240 | |
|
|
1241 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1242 | different event models feature vastly different performances, each event |
|
|
1243 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1244 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1245 | would probably take thousands of years if asked to process the same number |
|
|
1246 | of watchers as EV in this benchmark. |
|
|
1247 | |
|
|
1248 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1249 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1250 | and Perl-based overheads. |
|
|
1251 | |
|
|
1252 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1253 | takes to create a single watcher. The callback is a closure shared between |
|
|
1254 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1255 | and memory usage is not included in the figures. |
|
|
1256 | |
|
|
1257 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1258 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1259 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1260 | signal the end of this phase. |
|
|
1261 | |
|
|
1262 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1263 | watcher. |
|
|
1264 | |
|
|
1265 | =head3 Results |
|
|
1266 | |
|
|
1267 | name watchers bytes create invoke destroy comment |
|
|
1268 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1269 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1270 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1271 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1272 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1273 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1274 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1275 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1276 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1277 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1278 | |
|
|
1279 | =head3 Discussion |
|
|
1280 | |
|
|
1281 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1282 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1283 | can never compete with an event loop that uses epoll when the number of |
|
|
1284 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1285 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1286 | boost. |
|
|
1287 | |
|
|
1288 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1289 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1290 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1291 | higher number of watchers at a disadvantage. |
|
|
1292 | |
|
|
1293 | To put the range of results into perspective, consider that on the |
|
|
1294 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1295 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1296 | cycles with POE. |
|
|
1297 | |
|
|
1298 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1299 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1300 | far less memory than any other event loop and is still faster than Event |
|
|
1301 | natively. |
|
|
1302 | |
|
|
1303 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1304 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1305 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1306 | adds very little overhead in itself. Like any select-based backend its |
|
|
1307 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1308 | them active), of course, but this was not subject of this benchmark. |
|
|
1309 | |
|
|
1310 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1311 | cost, but overall scores in on the third place. |
|
|
1312 | |
|
|
1313 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1314 | faster callback invocation and overall ends up in the same class as |
|
|
1315 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1316 | watchers increases the processing time by more than a factor of four, |
|
|
1317 | making it completely unusable when using larger numbers of watchers |
|
|
1318 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1319 | inefficiencies of C<poll> do not account for this). |
|
|
1320 | |
|
|
1321 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1322 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1323 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1324 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1325 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1326 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1327 | above). |
|
|
1328 | |
|
|
1329 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1330 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1331 | be tested because it wasn't working) shows abysmal performance and |
|
|
1332 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1333 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1334 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1335 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1336 | implementation. |
|
|
1337 | |
|
|
1338 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1339 | for the performance issues, though, as session creation overhead is |
|
|
1340 | small compared to execution of the state machine, which is coded pretty |
|
|
1341 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1342 | using multiple sessions is not a good approach, especially regarding |
|
|
1343 | memory usage, even the author of POE could not come up with a faster |
|
|
1344 | design). |
|
|
1345 | |
|
|
1346 | =head3 Summary |
|
|
1347 | |
|
|
1348 | =over 4 |
|
|
1349 | |
|
|
1350 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1351 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1352 | performance with or without AnyEvent. |
|
|
1353 | |
|
|
1354 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1355 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1356 | adds AnyEvent significant overhead. |
|
|
1357 | |
|
|
1358 | =item * You should avoid POE like the plague if you want performance or |
|
|
1359 | reasonable memory usage. |
|
|
1360 | |
|
|
1361 | =back |
|
|
1362 | |
|
|
1363 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1364 | |
|
|
1365 | This benchmark atcually benchmarks the event loop itself. It works by |
|
|
1366 | creating a number of "servers": each server consists of a socketpair, a |
|
|
1367 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1368 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1369 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1370 | |
|
|
1371 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1372 | are active at any one point (so there is a constant number of active |
|
|
1373 | fds for each loop iterstaion, but which fds these are is random). The |
|
|
1374 | timeout is reset each time something is read because that reflects how |
|
|
1375 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1376 | |
|
|
1377 | In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 |
|
|
1378 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1379 | connections, most of which are idle at any one point in time. |
|
|
1380 | |
|
|
1381 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1382 | distribution. |
|
|
1383 | |
|
|
1384 | =head3 Explanation of the columns |
|
|
1385 | |
|
|
1386 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1387 | each server has a read and write socket end). |
|
|
1388 | |
|
|
1389 | I<create> is the time it takes to create a socketpair (which is |
|
|
1390 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1391 | |
|
|
1392 | I<request>, the most important value, is the time it takes to handle a |
|
|
1393 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1394 | it to another server. This includes deleting the old timeout and creating |
|
|
1395 | a new one that moves the timeout into the future. |
|
|
1396 | |
|
|
1397 | =head3 Results |
|
|
1398 | |
|
|
1399 | name sockets create request |
|
|
1400 | EV 20000 69.01 11.16 |
|
|
1401 | Perl 20000 73.32 35.87 |
|
|
1402 | Event 20000 212.62 257.32 |
|
|
1403 | Glib 20000 651.16 1896.30 |
|
|
1404 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1405 | |
|
|
1406 | =head3 Discussion |
|
|
1407 | |
|
|
1408 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1409 | particular event loop. |
|
|
1410 | |
|
|
1411 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1412 | is relatively high, though. |
|
|
1413 | |
|
|
1414 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1415 | loops Event and Glib. |
|
|
1416 | |
|
|
1417 | Event suffers from high setup time as well (look at its code and you will |
|
|
1418 | understand why). Callback invocation also has a high overhead compared to |
|
|
1419 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1420 | uses select or poll in basically all documented configurations. |
|
|
1421 | |
|
|
1422 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1423 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1424 | |
|
|
1425 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1426 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1427 | it uses a C-based event loop in this case. |
|
|
1428 | |
|
|
1429 | =head3 Summary |
|
|
1430 | |
|
|
1431 | =over 4 |
|
|
1432 | |
|
|
1433 | =item * The pure perl implementation performs extremely well. |
|
|
1434 | |
|
|
1435 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1436 | |
|
|
1437 | =back |
|
|
1438 | |
|
|
1439 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1440 | |
|
|
1441 | While event loops should scale (and select-based ones do not...) even to |
|
|
1442 | large servers, most programs we (or I :) actually write have only a few |
|
|
1443 | I/O watchers. |
|
|
1444 | |
|
|
1445 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1446 | case, but it uses only eight "servers", of which three are active at any |
|
|
1447 | one time. This should reflect performance for a small server relatively |
|
|
1448 | well. |
|
|
1449 | |
|
|
1450 | The columns are identical to the previous table. |
|
|
1451 | |
|
|
1452 | =head3 Results |
|
|
1453 | |
|
|
1454 | name sockets create request |
|
|
1455 | EV 16 20.00 6.54 |
|
|
1456 | Perl 16 25.75 12.62 |
|
|
1457 | Event 16 81.27 35.86 |
|
|
1458 | Glib 16 32.63 15.48 |
|
|
1459 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1460 | |
|
|
1461 | =head3 Discussion |
|
|
1462 | |
|
|
1463 | The benchmark tries to test the performance of a typical small |
|
|
1464 | server. While knowing how various event loops perform is interesting, keep |
|
|
1465 | in mind that their overhead in this case is usually not as important, due |
|
|
1466 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1467 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1468 | them). |
|
|
1469 | |
|
|
1470 | EV is again fastest. |
|
|
1471 | |
|
|
1472 | Perl again comes second. It is noticably faster than the C-based event |
|
|
1473 | loops Event and Glib, although the difference is too small to really |
|
|
1474 | matter. |
|
|
1475 | |
|
|
1476 | POE also performs much better in this case, but is is still far behind the |
|
|
1477 | others. |
|
|
1478 | |
|
|
1479 | =head3 Summary |
|
|
1480 | |
|
|
1481 | =over 4 |
|
|
1482 | |
|
|
1483 | =item * C-based event loops perform very well with small number of |
|
|
1484 | watchers, as the management overhead dominates. |
|
|
1485 | |
|
|
1486 | =back |
|
|
1487 | |
|
|
1488 | |
|
|
1489 | =head1 FORK |
|
|
1490 | |
|
|
1491 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1492 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1493 | calls. Only L<EV> is fully fork-aware. |
|
|
1494 | |
|
|
1495 | If you have to fork, you must either do so I<before> creating your first |
|
|
1496 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1497 | |
|
|
1498 | |
|
|
1499 | =head1 SECURITY CONSIDERATIONS |
|
|
1500 | |
|
|
1501 | AnyEvent can be forced to load any event model via |
|
|
1502 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1503 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1504 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1505 | will not be active when the program uses a different event model than |
|
|
1506 | specified in the variable. |
|
|
1507 | |
|
|
1508 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1509 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1510 | |
|
|
1511 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1512 | |
|
|
1513 | use AnyEvent; |
|
|
1514 | |
|
|
1515 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1516 | be used to probe what backend is used and gain other information (which is |
|
|
1517 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
|
|
1518 | |
328 | |
1519 | |
329 | =head1 SEE ALSO |
1520 | =head1 SEE ALSO |
330 | |
1521 | |
331 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
1522 | Utility functions: L<AnyEvent::Util>. |
332 | |
1523 | |
333 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
1524 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
|
|
1525 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
334 | |
1526 | |
335 | Nontrivial usage example: L<Net::FCP>. |
1527 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
|
|
1528 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
1529 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
1530 | L<AnyEvent::Impl::POE>. |
336 | |
1531 | |
337 | =head1 |
1532 | Non-blocking file handles, sockets, TCP clients and |
|
|
1533 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1534 | |
|
|
1535 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1536 | |
|
|
1537 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1538 | |
|
|
1539 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
|
|
1540 | |
|
|
1541 | |
|
|
1542 | =head1 AUTHOR |
|
|
1543 | |
|
|
1544 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1545 | http://home.schmorp.de/ |
338 | |
1546 | |
339 | =cut |
1547 | =cut |
340 | |
1548 | |
341 | 1 |
1549 | 1 |
342 | |
1550 | |