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 and POE are various supported |
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6 | event loops. |
6 | |
7 | |
7 | =head1 SYNOPSIS |
8 | =head1 SYNOPSIS |
8 | |
9 | |
9 | use AnyEvent; |
10 | use AnyEvent; |
10 | |
11 | |
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12 | # file descriptor readable |
11 | my $w = AnyEvent->io (fh => ..., poll => "[rw]+", cb => sub { |
13 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
12 | my ($poll_got) = @_; |
14 | |
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15 | # one-shot or repeating timers |
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16 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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17 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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18 | |
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19 | print AnyEvent->now; # prints current event loop time |
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20 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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21 | |
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22 | # POSIX signal |
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23 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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24 | |
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25 | # child process exit |
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26 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
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27 | my ($pid, $status) = @_; |
13 | ... |
28 | ... |
14 | }); |
29 | }); |
15 | |
30 | |
16 | * only one io watcher per $fh and $poll type is allowed (i.e. on a socket |
31 | # called when event loop idle (if applicable) |
17 | you can have one r + one w or one rw watcher, not any more (limitation by |
32 | my $w = AnyEvent->idle (cb => sub { ... }); |
18 | Tk). |
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19 | |
33 | |
20 | * the C<$poll_got> passed to the handler needs to be checked by looking |
34 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
21 | for single characters (e.g. with a regex), as it can contain more event |
35 | $w->send; # wake up current and all future recv's |
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 | |
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28 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
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29 | ... |
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30 | }); |
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31 | |
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32 | * io and time watchers get canceled whenever $w is destroyed, so keep a copy |
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33 | |
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34 | * timers can only be used once and must be recreated for repeated |
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35 | operation (limitation by Glib and Tk). |
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36 | |
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37 | my $w = AnyEvent->condvar; # kind of main loop replacement |
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38 | $w->wait; # enters main loop till $condvar gets ->broadcast |
36 | $w->recv; # enters "main loop" till $condvar gets ->send |
39 | $w->broadcast; # wake up current and all future wait's |
37 | # use a condvar in callback mode: |
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38 | $w->cb (sub { $_[0]->recv }); |
40 | |
39 | |
41 | * condvars are used to give blocking behaviour when neccessary. Create |
40 | =head1 INTRODUCTION/TUTORIAL |
42 | a condvar for any "request" or "event" your module might create, C<< |
41 | |
43 | ->broadcast >> it when the event happens and provide a function that calls |
42 | This manpage is mainly a reference manual. If you are interested |
44 | C<< ->wait >> for it. See the examples below. |
43 | in a tutorial or some gentle introduction, have a look at the |
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44 | L<AnyEvent::Intro> manpage. |
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45 | |
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46 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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47 | |
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48 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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49 | nowadays. So what is different about AnyEvent? |
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50 | |
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51 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
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52 | policy> and AnyEvent is I<small and efficient>. |
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53 | |
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54 | First and foremost, I<AnyEvent is not an event model> itself, it only |
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55 | interfaces to whatever event model the main program happens to use, in a |
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56 | pragmatic way. For event models and certain classes of immortals alike, |
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57 | the statement "there can only be one" is a bitter reality: In general, |
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58 | only one event loop can be active at the same time in a process. AnyEvent |
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59 | cannot change this, but it can hide the differences between those event |
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60 | loops. |
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61 | |
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62 | The goal of AnyEvent is to offer module authors the ability to do event |
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63 | programming (waiting for I/O or timer events) without subscribing to a |
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64 | religion, a way of living, and most importantly: without forcing your |
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65 | module users into the same thing by forcing them to use the same event |
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66 | model you use. |
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67 | |
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68 | For modules like POE or IO::Async (which is a total misnomer as it is |
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69 | actually doing all I/O I<synchronously>...), using them in your module is |
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70 | like joining a cult: After you joined, you are dependent on them and you |
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71 | cannot use anything else, as they are simply incompatible to everything |
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72 | that isn't them. What's worse, all the potential users of your |
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73 | module are I<also> forced to use the same event loop you use. |
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74 | |
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75 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
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76 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
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77 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if |
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78 | your module uses one of those, every user of your module has to use it, |
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79 | too. But if your module uses AnyEvent, it works transparently with all |
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80 | event models it supports (including stuff like IO::Async, as long as those |
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81 | use one of the supported event loops. It is trivial to add new event loops |
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82 | to AnyEvent, too, so it is future-proof). |
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83 | |
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84 | In addition to being free of having to use I<the one and only true event |
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85 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
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86 | modules, you get an enormous amount of code and strict rules you have to |
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87 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
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88 | offering the functionality that is necessary, in as thin as a wrapper as |
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89 | technically possible. |
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90 | |
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91 | Of course, AnyEvent comes with a big (and fully optional!) toolbox |
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92 | of useful functionality, such as an asynchronous DNS resolver, 100% |
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93 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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94 | such as Windows) and lots of real-world knowledge and workarounds for |
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95 | platform bugs and differences. |
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96 | |
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97 | Now, if you I<do want> lots of policy (this can arguably be somewhat |
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98 | useful) and you want to force your users to use the one and only event |
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99 | model, you should I<not> use this module. |
45 | |
100 | |
46 | =head1 DESCRIPTION |
101 | =head1 DESCRIPTION |
47 | |
102 | |
48 | L<AnyEvent> provides an identical interface to multiple event loops. This |
103 | L<AnyEvent> provides an identical interface to multiple event loops. This |
49 | allows module authors to utilise an event loop without forcing module |
104 | 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 |
105 | users to use the same event loop (as only a single event loop can coexist |
51 | peacefully at any one time). |
106 | peacefully at any one time). |
52 | |
107 | |
53 | The interface itself is vaguely similar but not identical to the Event |
108 | The interface itself is vaguely similar, but not identical to the L<Event> |
54 | module. |
109 | module. |
55 | |
110 | |
56 | On the first call of any method, the module tries to detect the currently |
111 | 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 |
112 | 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 |
113 | following modules is already loaded: L<EV>, |
59 | used. If none is found, the module tries to load these modules in the |
114 | 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 |
115 | 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. |
116 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
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117 | adaptor should always succeed) in the order given. The first one that can |
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118 | be successfully loaded will be used. If, after this, still none could be |
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119 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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120 | very efficient, but should work everywhere. |
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121 | |
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122 | Because AnyEvent first checks for modules that are already loaded, loading |
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123 | an event model explicitly before first using AnyEvent will likely make |
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124 | that model the default. For example: |
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125 | |
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126 | use Tk; |
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127 | use AnyEvent; |
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128 | |
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129 | # .. AnyEvent will likely default to Tk |
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130 | |
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131 | The I<likely> means that, if any module loads another event model and |
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132 | starts using it, all bets are off. Maybe you should tell their authors to |
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133 | use AnyEvent so their modules work together with others seamlessly... |
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134 | |
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135 | The pure-perl implementation of AnyEvent is called |
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136 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
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137 | explicitly and enjoy the high availability of that event loop :) |
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138 | |
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139 | =head1 WATCHERS |
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140 | |
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141 | AnyEvent has the central concept of a I<watcher>, which is an object that |
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142 | stores relevant data for each kind of event you are waiting for, such as |
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143 | the callback to call, the file handle to watch, etc. |
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144 | |
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145 | These watchers are normal Perl objects with normal Perl lifetime. After |
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146 | creating a watcher it will immediately "watch" for events and invoke the |
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147 | callback when the event occurs (of course, only when the event model |
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148 | is in control). |
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149 | |
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150 | Note that B<callbacks must not permanently change global variables> |
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151 | potentially in use by the event loop (such as C<$_> or C<$[>) and that B<< |
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152 | callbacks must not C<die> >>. The former is good programming practise in |
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153 | Perl and the latter stems from the fact that exception handling differs |
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154 | widely between event loops. |
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155 | |
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156 | To disable the watcher you have to destroy it (e.g. by setting the |
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157 | variable you store it in to C<undef> or otherwise deleting all references |
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158 | to it). |
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159 | |
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160 | All watchers are created by calling a method on the C<AnyEvent> class. |
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161 | |
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162 | Many watchers either are used with "recursion" (repeating timers for |
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163 | example), or need to refer to their watcher object in other ways. |
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164 | |
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165 | An any way to achieve that is this pattern: |
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166 | |
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167 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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168 | # you can use $w here, for example to undef it |
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169 | undef $w; |
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170 | }); |
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171 | |
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172 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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173 | my variables are only visible after the statement in which they are |
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174 | declared. |
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175 | |
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176 | =head2 I/O WATCHERS |
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177 | |
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178 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
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179 | with the following mandatory key-value pairs as arguments: |
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180 | |
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181 | C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch |
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182 | for events (AnyEvent might or might not keep a reference to this file |
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183 | handle). Note that only file handles pointing to things for which |
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184 | non-blocking operation makes sense are allowed. This includes sockets, |
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185 | most character devices, pipes, fifos and so on, but not for example files |
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186 | or block devices. |
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187 | |
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188 | C<poll> must be a string that is either C<r> or C<w>, which creates a |
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189 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
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190 | |
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191 | C<cb> is the callback to invoke each time the file handle becomes ready. |
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192 | |
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193 | Although the callback might get passed parameters, their value and |
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194 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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195 | callbacks cannot use arguments passed to I/O watcher callbacks. |
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196 | |
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197 | The I/O watcher might use the underlying file descriptor or a copy of it. |
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198 | You must not close a file handle as long as any watcher is active on the |
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199 | underlying file descriptor. |
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200 | |
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201 | Some event loops issue spurious readyness notifications, so you should |
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202 | always use non-blocking calls when reading/writing from/to your file |
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203 | handles. |
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204 | |
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205 | Example: wait for readability of STDIN, then read a line and disable the |
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206 | watcher. |
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207 | |
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208 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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209 | chomp (my $input = <STDIN>); |
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210 | warn "read: $input\n"; |
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211 | undef $w; |
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212 | }); |
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213 | |
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214 | =head2 TIME WATCHERS |
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215 | |
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216 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
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217 | method with the following mandatory arguments: |
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218 | |
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219 | C<after> specifies after how many seconds (fractional values are |
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220 | supported) the callback should be invoked. C<cb> is the callback to invoke |
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221 | in that case. |
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222 | |
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223 | Although the callback might get passed parameters, their value and |
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224 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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225 | callbacks cannot use arguments passed to time watcher callbacks. |
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226 | |
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227 | The callback will normally be invoked once only. If you specify another |
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228 | parameter, C<interval>, as a strictly positive number (> 0), then the |
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229 | callback will be invoked regularly at that interval (in fractional |
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230 | seconds) after the first invocation. If C<interval> is specified with a |
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231 | false value, then it is treated as if it were missing. |
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232 | |
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233 | The callback will be rescheduled before invoking the callback, but no |
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234 | attempt is done to avoid timer drift in most backends, so the interval is |
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235 | only approximate. |
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236 | |
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237 | Example: fire an event after 7.7 seconds. |
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238 | |
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239 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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240 | warn "timeout\n"; |
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241 | }); |
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242 | |
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243 | # to cancel the timer: |
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244 | undef $w; |
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245 | |
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246 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
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247 | |
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248 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
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249 | warn "timeout\n"; |
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250 | }; |
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251 | |
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252 | =head3 TIMING ISSUES |
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253 | |
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254 | There are two ways to handle timers: based on real time (relative, "fire |
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255 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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256 | o'clock"). |
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257 | |
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258 | While most event loops expect timers to specified in a relative way, they |
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259 | use absolute time internally. This makes a difference when your clock |
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260 | "jumps", for example, when ntp decides to set your clock backwards from |
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261 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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262 | fire "after" a second might actually take six years to finally fire. |
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263 | |
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264 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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265 | about these issues is L<EV>, which offers both relative (ev_timer, based |
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266 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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267 | timers. |
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268 | |
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269 | AnyEvent always prefers relative timers, if available, matching the |
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270 | AnyEvent API. |
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271 | |
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272 | AnyEvent has two additional methods that return the "current time": |
62 | |
273 | |
63 | =over 4 |
274 | =over 4 |
64 | |
275 | |
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276 | =item AnyEvent->time |
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277 | |
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278 | This returns the "current wallclock time" as a fractional number of |
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279 | seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time> |
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280 | return, and the result is guaranteed to be compatible with those). |
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281 | |
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282 | It progresses independently of any event loop processing, i.e. each call |
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283 | will check the system clock, which usually gets updated frequently. |
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284 | |
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285 | =item AnyEvent->now |
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286 | |
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287 | This also returns the "current wallclock time", but unlike C<time>, above, |
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288 | this value might change only once per event loop iteration, depending on |
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289 | the event loop (most return the same time as C<time>, above). This is the |
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290 | time that AnyEvent's timers get scheduled against. |
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291 | |
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292 | I<In almost all cases (in all cases if you don't care), this is the |
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293 | function to call when you want to know the current time.> |
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294 | |
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295 | This function is also often faster then C<< AnyEvent->time >>, and |
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296 | thus the preferred method if you want some timestamp (for example, |
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297 | L<AnyEvent::Handle> uses this to update it's activity timeouts). |
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298 | |
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299 | The rest of this section is only of relevance if you try to be very exact |
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300 | with your timing, you can skip it without bad conscience. |
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301 | |
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302 | For a practical example of when these times differ, consider L<Event::Lib> |
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303 | and L<EV> and the following set-up: |
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304 | |
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305 | The event loop is running and has just invoked one of your callback at |
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306 | time=500 (assume no other callbacks delay processing). In your callback, |
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307 | you wait a second by executing C<sleep 1> (blocking the process for a |
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308 | second) and then (at time=501) you create a relative timer that fires |
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309 | after three seconds. |
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310 | |
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311 | With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will |
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312 | both return C<501>, because that is the current time, and the timer will |
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313 | be scheduled to fire at time=504 (C<501> + C<3>). |
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314 | |
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315 | With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current |
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316 | time), but C<< AnyEvent->now >> returns C<500>, as that is the time the |
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317 | last event processing phase started. With L<EV>, your timer gets scheduled |
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318 | to run at time=503 (C<500> + C<3>). |
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319 | |
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320 | In one sense, L<Event::Lib> is more exact, as it uses the current time |
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321 | regardless of any delays introduced by event processing. However, most |
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322 | callbacks do not expect large delays in processing, so this causes a |
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323 | higher drift (and a lot more system calls to get the current time). |
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324 | |
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325 | In another sense, L<EV> is more exact, as your timer will be scheduled at |
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326 | the same time, regardless of how long event processing actually took. |
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327 | |
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328 | In either case, if you care (and in most cases, you don't), then you |
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329 | can get whatever behaviour you want with any event loop, by taking the |
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330 | difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into |
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331 | account. |
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332 | |
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333 | =item AnyEvent->now_update |
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334 | |
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335 | Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache |
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336 | the current time for each loop iteration (see the discussion of L<< |
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337 | AnyEvent->now >>, above). |
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338 | |
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339 | When a callback runs for a long time (or when the process sleeps), then |
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340 | this "current" time will differ substantially from the real time, which |
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341 | might affect timers and time-outs. |
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342 | |
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343 | When this is the case, you can call this method, which will update the |
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344 | event loop's idea of "current time". |
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345 | |
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346 | Note that updating the time I<might> cause some events to be handled. |
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347 | |
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348 | =back |
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349 | |
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350 | =head2 SIGNAL WATCHERS |
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351 | |
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352 | You can watch for signals using a signal watcher, C<signal> is the signal |
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353 | I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl |
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354 | callback to be invoked whenever a signal occurs. |
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355 | |
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356 | Although the callback might get passed parameters, their value and |
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357 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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358 | callbacks cannot use arguments passed to signal watcher callbacks. |
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359 | |
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360 | Multiple signal occurrences can be clumped together into one callback |
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361 | invocation, and callback invocation will be synchronous. Synchronous means |
|
|
362 | that it might take a while until the signal gets handled by the process, |
|
|
363 | but it is guaranteed not to interrupt any other callbacks. |
|
|
364 | |
|
|
365 | The main advantage of using these watchers is that you can share a signal |
|
|
366 | between multiple watchers. |
|
|
367 | |
|
|
368 | This watcher might use C<%SIG>, so programs overwriting those signals |
|
|
369 | directly will likely not work correctly. |
|
|
370 | |
|
|
371 | Example: exit on SIGINT |
|
|
372 | |
|
|
373 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
374 | |
|
|
375 | =head2 CHILD PROCESS WATCHERS |
|
|
376 | |
|
|
377 | You can also watch on a child process exit and catch its exit status. |
|
|
378 | |
|
|
379 | The child process is specified by the C<pid> argument (if set to C<0>, it |
|
|
380 | watches for any child process exit). The watcher will triggered only when |
|
|
381 | the child process has finished and an exit status is available, not on |
|
|
382 | any trace events (stopped/continued). |
|
|
383 | |
|
|
384 | The callback will be called with the pid and exit status (as returned by |
|
|
385 | waitpid), so unlike other watcher types, you I<can> rely on child watcher |
|
|
386 | callback arguments. |
|
|
387 | |
|
|
388 | This watcher type works by installing a signal handler for C<SIGCHLD>, |
|
|
389 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
|
|
390 | random child processes (waiting for specific child processes, e.g. inside |
|
|
391 | C<system>, is just fine). |
|
|
392 | |
|
|
393 | There is a slight catch to child watchers, however: you usually start them |
|
|
394 | I<after> the child process was created, and this means the process could |
|
|
395 | have exited already (and no SIGCHLD will be sent anymore). |
|
|
396 | |
|
|
397 | Not all event models handle this correctly (neither POE nor IO::Async do, |
|
|
398 | see their AnyEvent::Impl manpages for details), but even for event models |
|
|
399 | that I<do> handle this correctly, they usually need to be loaded before |
|
|
400 | the process exits (i.e. before you fork in the first place). AnyEvent's |
|
|
401 | pure perl event loop handles all cases correctly regardless of when you |
|
|
402 | start the watcher. |
|
|
403 | |
|
|
404 | This means you cannot create a child watcher as the very first |
|
|
405 | thing in an AnyEvent program, you I<have> to create at least one |
|
|
406 | watcher before you C<fork> the child (alternatively, you can call |
|
|
407 | C<AnyEvent::detect>). |
|
|
408 | |
|
|
409 | Example: fork a process and wait for it |
|
|
410 | |
|
|
411 | my $done = AnyEvent->condvar; |
|
|
412 | |
|
|
413 | my $pid = fork or exit 5; |
|
|
414 | |
|
|
415 | my $w = AnyEvent->child ( |
|
|
416 | pid => $pid, |
|
|
417 | cb => sub { |
|
|
418 | my ($pid, $status) = @_; |
|
|
419 | warn "pid $pid exited with status $status"; |
|
|
420 | $done->send; |
|
|
421 | }, |
|
|
422 | ); |
|
|
423 | |
|
|
424 | # do something else, then wait for process exit |
|
|
425 | $done->recv; |
|
|
426 | |
|
|
427 | =head2 IDLE WATCHERS |
|
|
428 | |
|
|
429 | Sometimes there is a need to do something, but it is not so important |
|
|
430 | to do it instantly, but only when there is nothing better to do. This |
|
|
431 | "nothing better to do" is usually defined to be "no other events need |
|
|
432 | attention by the event loop". |
|
|
433 | |
|
|
434 | Idle watchers ideally get invoked when the event loop has nothing |
|
|
435 | better to do, just before it would block the process to wait for new |
|
|
436 | events. Instead of blocking, the idle watcher is invoked. |
|
|
437 | |
|
|
438 | Most event loops unfortunately do not really support idle watchers (only |
|
|
439 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
|
|
440 | will simply call the callback "from time to time". |
|
|
441 | |
|
|
442 | Example: read lines from STDIN, but only process them when the |
|
|
443 | program is otherwise idle: |
|
|
444 | |
|
|
445 | my @lines; # read data |
|
|
446 | my $idle_w; |
|
|
447 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
|
|
448 | push @lines, scalar <STDIN>; |
|
|
449 | |
|
|
450 | # start an idle watcher, if not already done |
|
|
451 | $idle_w ||= AnyEvent->idle (cb => sub { |
|
|
452 | # handle only one line, when there are lines left |
|
|
453 | if (my $line = shift @lines) { |
|
|
454 | print "handled when idle: $line"; |
|
|
455 | } else { |
|
|
456 | # otherwise disable the idle watcher again |
|
|
457 | undef $idle_w; |
|
|
458 | } |
|
|
459 | }); |
|
|
460 | }); |
|
|
461 | |
|
|
462 | =head2 CONDITION VARIABLES |
|
|
463 | |
|
|
464 | If you are familiar with some event loops you will know that all of them |
|
|
465 | require you to run some blocking "loop", "run" or similar function that |
|
|
466 | will actively watch for new events and call your callbacks. |
|
|
467 | |
|
|
468 | AnyEvent is different, it expects somebody else to run the event loop and |
|
|
469 | will only block when necessary (usually when told by the user). |
|
|
470 | |
|
|
471 | The instrument to do that is called a "condition variable", so called |
|
|
472 | because they represent a condition that must become true. |
|
|
473 | |
|
|
474 | Condition variables can be created by calling the C<< AnyEvent->condvar |
|
|
475 | >> method, usually without arguments. The only argument pair allowed is |
|
|
476 | |
|
|
477 | C<cb>, which specifies a callback to be called when the condition variable |
|
|
478 | becomes true, with the condition variable as the first argument (but not |
|
|
479 | the results). |
|
|
480 | |
|
|
481 | After creation, the condition variable is "false" until it becomes "true" |
|
|
482 | by calling the C<send> method (or calling the condition variable as if it |
|
|
483 | were a callback, read about the caveats in the description for the C<< |
|
|
484 | ->send >> method). |
|
|
485 | |
|
|
486 | Condition variables are similar to callbacks, except that you can |
|
|
487 | optionally wait for them. They can also be called merge points - points |
|
|
488 | in time where multiple outstanding events have been processed. And yet |
|
|
489 | another way to call them is transactions - each condition variable can be |
|
|
490 | used to represent a transaction, which finishes at some point and delivers |
|
|
491 | a result. |
|
|
492 | |
|
|
493 | Condition variables are very useful to signal that something has finished, |
|
|
494 | for example, if you write a module that does asynchronous http requests, |
|
|
495 | then a condition variable would be the ideal candidate to signal the |
|
|
496 | availability of results. The user can either act when the callback is |
|
|
497 | called or can synchronously C<< ->recv >> for the results. |
|
|
498 | |
|
|
499 | You can also use them to simulate traditional event loops - for example, |
|
|
500 | you can block your main program until an event occurs - for example, you |
|
|
501 | could C<< ->recv >> in your main program until the user clicks the Quit |
|
|
502 | button of your app, which would C<< ->send >> the "quit" event. |
|
|
503 | |
|
|
504 | Note that condition variables recurse into the event loop - if you have |
|
|
505 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
|
|
506 | lose. Therefore, condition variables are good to export to your caller, but |
|
|
507 | you should avoid making a blocking wait yourself, at least in callbacks, |
|
|
508 | as this asks for trouble. |
|
|
509 | |
|
|
510 | Condition variables are represented by hash refs in perl, and the keys |
|
|
511 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
|
|
512 | easy (it is often useful to build your own transaction class on top of |
|
|
513 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
|
|
514 | it's C<new> method in your own C<new> method. |
|
|
515 | |
|
|
516 | There are two "sides" to a condition variable - the "producer side" which |
|
|
517 | eventually calls C<< -> send >>, and the "consumer side", which waits |
|
|
518 | for the send to occur. |
|
|
519 | |
|
|
520 | Example: wait for a timer. |
|
|
521 | |
|
|
522 | # wait till the result is ready |
|
|
523 | my $result_ready = AnyEvent->condvar; |
|
|
524 | |
|
|
525 | # do something such as adding a timer |
|
|
526 | # or socket watcher the calls $result_ready->send |
|
|
527 | # when the "result" is ready. |
|
|
528 | # in this case, we simply use a timer: |
|
|
529 | my $w = AnyEvent->timer ( |
|
|
530 | after => 1, |
|
|
531 | cb => sub { $result_ready->send }, |
|
|
532 | ); |
|
|
533 | |
|
|
534 | # this "blocks" (while handling events) till the callback |
|
|
535 | # calls send |
|
|
536 | $result_ready->recv; |
|
|
537 | |
|
|
538 | Example: wait for a timer, but take advantage of the fact that |
|
|
539 | condition variables are also code references. |
|
|
540 | |
|
|
541 | my $done = AnyEvent->condvar; |
|
|
542 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
|
|
543 | $done->recv; |
|
|
544 | |
|
|
545 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
546 | callbacks. This is how you make a synchronous call, for example from |
|
|
547 | the main program: |
|
|
548 | |
|
|
549 | use AnyEvent::CouchDB; |
|
|
550 | |
|
|
551 | ... |
|
|
552 | |
|
|
553 | my @info = $couchdb->info->recv; |
|
|
554 | |
|
|
555 | And this is how you would just ste a callback to be called whenever the |
|
|
556 | results are available: |
|
|
557 | |
|
|
558 | $couchdb->info->cb (sub { |
|
|
559 | my @info = $_[0]->recv; |
|
|
560 | }); |
|
|
561 | |
|
|
562 | =head3 METHODS FOR PRODUCERS |
|
|
563 | |
|
|
564 | These methods should only be used by the producing side, i.e. the |
|
|
565 | code/module that eventually sends the signal. Note that it is also |
|
|
566 | the producer side which creates the condvar in most cases, but it isn't |
|
|
567 | uncommon for the consumer to create it as well. |
|
|
568 | |
|
|
569 | =over 4 |
|
|
570 | |
|
|
571 | =item $cv->send (...) |
|
|
572 | |
|
|
573 | Flag the condition as ready - a running C<< ->recv >> and all further |
|
|
574 | calls to C<recv> will (eventually) return after this method has been |
|
|
575 | called. If nobody is waiting the send will be remembered. |
|
|
576 | |
|
|
577 | If a callback has been set on the condition variable, it is called |
|
|
578 | immediately from within send. |
|
|
579 | |
|
|
580 | Any arguments passed to the C<send> call will be returned by all |
|
|
581 | future C<< ->recv >> calls. |
|
|
582 | |
|
|
583 | Condition variables are overloaded so one can call them directly |
|
|
584 | (as a code reference). Calling them directly is the same as calling |
|
|
585 | C<send>. Note, however, that many C-based event loops do not handle |
|
|
586 | overloading, so as tempting as it may be, passing a condition variable |
|
|
587 | instead of a callback does not work. Both the pure perl and EV loops |
|
|
588 | support overloading, however, as well as all functions that use perl to |
|
|
589 | invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for |
|
|
590 | example). |
|
|
591 | |
|
|
592 | =item $cv->croak ($error) |
|
|
593 | |
|
|
594 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
|
|
595 | C<Carp::croak> with the given error message/object/scalar. |
|
|
596 | |
|
|
597 | This can be used to signal any errors to the condition variable |
|
|
598 | user/consumer. |
|
|
599 | |
|
|
600 | =item $cv->begin ([group callback]) |
|
|
601 | |
|
|
602 | =item $cv->end |
|
|
603 | |
|
|
604 | These two methods can be used to combine many transactions/events into |
|
|
605 | one. For example, a function that pings many hosts in parallel might want |
|
|
606 | to use a condition variable for the whole process. |
|
|
607 | |
|
|
608 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
609 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
610 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
611 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
612 | callback was set, C<send> will be called without any arguments. |
|
|
613 | |
|
|
614 | You can think of C<< $cv->send >> giving you an OR condition (one call |
|
|
615 | sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND |
|
|
616 | condition (all C<begin> calls must be C<end>'ed before the condvar sends). |
|
|
617 | |
|
|
618 | Let's start with a simple example: you have two I/O watchers (for example, |
|
|
619 | STDOUT and STDERR for a program), and you want to wait for both streams to |
|
|
620 | close before activating a condvar: |
|
|
621 | |
|
|
622 | my $cv = AnyEvent->condvar; |
|
|
623 | |
|
|
624 | $cv->begin; # first watcher |
|
|
625 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
|
|
626 | defined sysread $fh1, my $buf, 4096 |
|
|
627 | or $cv->end; |
|
|
628 | }); |
|
|
629 | |
|
|
630 | $cv->begin; # second watcher |
|
|
631 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
|
|
632 | defined sysread $fh2, my $buf, 4096 |
|
|
633 | or $cv->end; |
|
|
634 | }); |
|
|
635 | |
|
|
636 | $cv->recv; |
|
|
637 | |
|
|
638 | This works because for every event source (EOF on file handle), there is |
|
|
639 | one call to C<begin>, so the condvar waits for all calls to C<end> before |
|
|
640 | sending. |
|
|
641 | |
|
|
642 | The ping example mentioned above is slightly more complicated, as the |
|
|
643 | there are results to be passwd back, and the number of tasks that are |
|
|
644 | begung can potentially be zero: |
|
|
645 | |
|
|
646 | my $cv = AnyEvent->condvar; |
|
|
647 | |
|
|
648 | my %result; |
|
|
649 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
650 | |
|
|
651 | for my $host (@list_of_hosts) { |
|
|
652 | $cv->begin; |
|
|
653 | ping_host_then_call_callback $host, sub { |
|
|
654 | $result{$host} = ...; |
|
|
655 | $cv->end; |
|
|
656 | }; |
|
|
657 | } |
|
|
658 | |
|
|
659 | $cv->end; |
|
|
660 | |
|
|
661 | This code fragment supposedly pings a number of hosts and calls |
|
|
662 | C<send> after results for all then have have been gathered - in any |
|
|
663 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
664 | each ping request and calls C<end> when it has received some result for |
|
|
665 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
666 | results arrive is not relevant. |
|
|
667 | |
|
|
668 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
669 | loop, which serves two important purposes: first, it sets the callback |
|
|
670 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
671 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
672 | doesn't execute once). |
|
|
673 | |
|
|
674 | This is the general pattern when you "fan out" into multiple (but |
|
|
675 | potentially none) subrequests: use an outer C<begin>/C<end> pair to set |
|
|
676 | the callback and ensure C<end> is called at least once, and then, for each |
|
|
677 | subrequest you start, call C<begin> and for each subrequest you finish, |
|
|
678 | call C<end>. |
|
|
679 | |
|
|
680 | =back |
|
|
681 | |
|
|
682 | =head3 METHODS FOR CONSUMERS |
|
|
683 | |
|
|
684 | These methods should only be used by the consuming side, i.e. the |
|
|
685 | code awaits the condition. |
|
|
686 | |
|
|
687 | =over 4 |
|
|
688 | |
|
|
689 | =item $cv->recv |
|
|
690 | |
|
|
691 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
|
|
692 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
693 | normally. |
|
|
694 | |
|
|
695 | You can only wait once on a condition - additional calls are valid but |
|
|
696 | will return immediately. |
|
|
697 | |
|
|
698 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
699 | function will call C<croak>. |
|
|
700 | |
|
|
701 | In list context, all parameters passed to C<send> will be returned, |
|
|
702 | in scalar context only the first one will be returned. |
|
|
703 | |
|
|
704 | Not all event models support a blocking wait - some die in that case |
|
|
705 | (programs might want to do that to stay interactive), so I<if you are |
|
|
706 | using this from a module, never require a blocking wait>, but let the |
|
|
707 | caller decide whether the call will block or not (for example, by coupling |
|
|
708 | condition variables with some kind of request results and supporting |
|
|
709 | callbacks so the caller knows that getting the result will not block, |
|
|
710 | while still supporting blocking waits if the caller so desires). |
|
|
711 | |
|
|
712 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
|
|
713 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
|
|
714 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
|
|
715 | can supply. |
|
|
716 | |
|
|
717 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
718 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
719 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
720 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
721 | coroutine (one that doesn't run the event loop). |
|
|
722 | |
|
|
723 | You can ensure that C<< -recv >> never blocks by setting a callback and |
|
|
724 | only calling C<< ->recv >> from within that callback (or at a later |
|
|
725 | time). This will work even when the event loop does not support blocking |
|
|
726 | waits otherwise. |
|
|
727 | |
|
|
728 | =item $bool = $cv->ready |
|
|
729 | |
|
|
730 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
731 | C<croak> have been called. |
|
|
732 | |
|
|
733 | =item $cb = $cv->cb ($cb->($cv)) |
|
|
734 | |
|
|
735 | This is a mutator function that returns the callback set and optionally |
|
|
736 | replaces it before doing so. |
|
|
737 | |
|
|
738 | The callback will be called when the condition becomes "true", i.e. when |
|
|
739 | C<send> or C<croak> are called, with the only argument being the condition |
|
|
740 | variable itself. Calling C<recv> inside the callback or at any later time |
|
|
741 | is guaranteed not to block. |
|
|
742 | |
|
|
743 | =back |
|
|
744 | |
|
|
745 | =head1 SUPPORTED EVENT LOOPS/BACKENDS |
|
|
746 | |
|
|
747 | The available backend classes are (every class has its own manpage): |
|
|
748 | |
|
|
749 | =over 4 |
|
|
750 | |
|
|
751 | =item Backends that are autoprobed when no other event loop can be found. |
|
|
752 | |
|
|
753 | EV is the preferred backend when no other event loop seems to be in |
|
|
754 | use. If EV is not installed, then AnyEvent will try Event, and, failing |
|
|
755 | that, will fall back to its own pure-perl implementation, which is |
|
|
756 | available everywhere as it comes with AnyEvent itself. |
|
|
757 | |
|
|
758 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
|
|
759 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
760 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
761 | |
|
|
762 | =item Backends that are transparently being picked up when they are used. |
|
|
763 | |
|
|
764 | These will be used when they are currently loaded when the first watcher |
|
|
765 | is created, in which case it is assumed that the application is using |
|
|
766 | them. This means that AnyEvent will automatically pick the right backend |
|
|
767 | when the main program loads an event module before anything starts to |
|
|
768 | create watchers. Nothing special needs to be done by the main program. |
|
|
769 | |
|
|
770 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
|
|
771 | AnyEvent::Impl::Tk based on Tk, very broken. |
|
|
772 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
773 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
774 | |
|
|
775 | =item Backends with special needs. |
|
|
776 | |
|
|
777 | Qt requires the Qt::Application to be instantiated first, but will |
|
|
778 | otherwise be picked up automatically. As long as the main program |
|
|
779 | instantiates the application before any AnyEvent watchers are created, |
|
|
780 | everything should just work. |
|
|
781 | |
|
|
782 | AnyEvent::Impl::Qt based on Qt. |
|
|
783 | |
|
|
784 | Support for IO::Async can only be partial, as it is too broken and |
|
|
785 | architecturally limited to even support the AnyEvent API. It also |
|
|
786 | is the only event loop that needs the loop to be set explicitly, so |
|
|
787 | it can only be used by a main program knowing about AnyEvent. See |
|
|
788 | L<AnyEvent::Impl::Async> for the gory details. |
|
|
789 | |
|
|
790 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
791 | |
|
|
792 | =item Event loops that are indirectly supported via other backends. |
|
|
793 | |
|
|
794 | Some event loops can be supported via other modules: |
|
|
795 | |
|
|
796 | There is no direct support for WxWidgets (L<Wx>) or L<Prima>. |
|
|
797 | |
|
|
798 | B<WxWidgets> has no support for watching file handles. However, you can |
|
|
799 | use WxWidgets through the POE adaptor, as POE has a Wx backend that simply |
|
|
800 | polls 20 times per second, which was considered to be too horrible to even |
|
|
801 | consider for AnyEvent. |
|
|
802 | |
|
|
803 | B<Prima> is not supported as nobody seems to be using it, but it has a POE |
|
|
804 | backend, so it can be supported through POE. |
|
|
805 | |
|
|
806 | AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to |
|
|
807 | load L<POE> when detecting them, in the hope that POE will pick them up, |
|
|
808 | in which case everything will be automatic. |
|
|
809 | |
|
|
810 | =back |
|
|
811 | |
|
|
812 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
|
|
813 | |
|
|
814 | =over 4 |
|
|
815 | |
|
|
816 | =item $AnyEvent::MODEL |
|
|
817 | |
|
|
818 | Contains C<undef> until the first watcher is being created. Then it |
|
|
819 | contains the event model that is being used, which is the name of the |
|
|
820 | Perl class implementing the model. This class is usually one of the |
|
|
821 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
|
|
822 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
|
|
823 | |
|
|
824 | =item AnyEvent::detect |
|
|
825 | |
|
|
826 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
|
|
827 | if necessary. You should only call this function right before you would |
|
|
828 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
829 | runtime. |
|
|
830 | |
|
|
831 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
832 | |
|
|
833 | Arranges for the code block to be executed as soon as the event model is |
|
|
834 | autodetected (or immediately if this has already happened). |
|
|
835 | |
|
|
836 | If called in scalar or list context, then it creates and returns an object |
|
|
837 | that automatically removes the callback again when it is destroyed. See |
|
|
838 | L<Coro::BDB> for a case where this is useful. |
|
|
839 | |
|
|
840 | =item @AnyEvent::post_detect |
|
|
841 | |
|
|
842 | If there are any code references in this array (you can C<push> to it |
|
|
843 | before or after loading AnyEvent), then they will called directly after |
|
|
844 | the event loop has been chosen. |
|
|
845 | |
|
|
846 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
847 | if it contains a true value then the event loop has already been detected, |
|
|
848 | and the array will be ignored. |
|
|
849 | |
|
|
850 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
|
|
851 | |
|
|
852 | =back |
|
|
853 | |
|
|
854 | =head1 WHAT TO DO IN A MODULE |
|
|
855 | |
|
|
856 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
|
|
857 | freely, but you should not load a specific event module or rely on it. |
|
|
858 | |
|
|
859 | Be careful when you create watchers in the module body - AnyEvent will |
|
|
860 | decide which event module to use as soon as the first method is called, so |
|
|
861 | by calling AnyEvent in your module body you force the user of your module |
|
|
862 | to load the event module first. |
|
|
863 | |
|
|
864 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
|
|
865 | the C<< ->send >> method has been called on it already. This is |
|
|
866 | because it will stall the whole program, and the whole point of using |
|
|
867 | events is to stay interactive. |
|
|
868 | |
|
|
869 | It is fine, however, to call C<< ->recv >> when the user of your module |
|
|
870 | requests it (i.e. if you create a http request object ad have a method |
|
|
871 | called C<results> that returns the results, it should call C<< ->recv >> |
|
|
872 | freely, as the user of your module knows what she is doing. always). |
|
|
873 | |
|
|
874 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
|
|
875 | |
|
|
876 | There will always be a single main program - the only place that should |
|
|
877 | dictate which event model to use. |
|
|
878 | |
|
|
879 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
|
|
880 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
881 | decide which implementation to chose if some module relies on it. |
|
|
882 | |
|
|
883 | If the main program relies on a specific event model - for example, in |
|
|
884 | Gtk2 programs you have to rely on the Glib module - you should load the |
|
|
885 | event module before loading AnyEvent or any module that uses it: generally |
|
|
886 | speaking, you should load it as early as possible. The reason is that |
|
|
887 | modules might create watchers when they are loaded, and AnyEvent will |
|
|
888 | decide on the event model to use as soon as it creates watchers, and it |
|
|
889 | might chose the wrong one unless you load the correct one yourself. |
|
|
890 | |
|
|
891 | You can chose to use a pure-perl implementation by loading the |
|
|
892 | C<AnyEvent::Impl::Perl> module, which gives you similar behaviour |
|
|
893 | everywhere, but letting AnyEvent chose the model is generally better. |
|
|
894 | |
|
|
895 | =head2 MAINLOOP EMULATION |
|
|
896 | |
|
|
897 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
898 | only want to use AnyEvent), you do not want to run a specific event loop. |
|
|
899 | |
|
|
900 | In that case, you can use a condition variable like this: |
|
|
901 | |
|
|
902 | AnyEvent->condvar->recv; |
|
|
903 | |
|
|
904 | This has the effect of entering the event loop and looping forever. |
|
|
905 | |
|
|
906 | Note that usually your program has some exit condition, in which case |
|
|
907 | it is better to use the "traditional" approach of storing a condition |
|
|
908 | variable somewhere, waiting for it, and sending it when the program should |
|
|
909 | exit cleanly. |
|
|
910 | |
|
|
911 | |
|
|
912 | =head1 OTHER MODULES |
|
|
913 | |
|
|
914 | The following is a non-exhaustive list of additional modules that use |
|
|
915 | AnyEvent as a client and can therefore be mixed easily with other AnyEvent |
|
|
916 | modules and other event loops in the same program. Some of the modules |
|
|
917 | come with AnyEvent, most are available via CPAN. |
|
|
918 | |
|
|
919 | =over 4 |
|
|
920 | |
|
|
921 | =item L<AnyEvent::Util> |
|
|
922 | |
|
|
923 | Contains various utility functions that replace often-used but blocking |
|
|
924 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
925 | |
|
|
926 | =item L<AnyEvent::Socket> |
|
|
927 | |
|
|
928 | Provides various utility functions for (internet protocol) sockets, |
|
|
929 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
930 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
931 | |
|
|
932 | =item L<AnyEvent::Handle> |
|
|
933 | |
|
|
934 | Provide read and write buffers, manages watchers for reads and writes, |
|
|
935 | supports raw and formatted I/O, I/O queued and fully transparent and |
|
|
936 | non-blocking SSL/TLS (via L<AnyEvent::TLS>. |
|
|
937 | |
|
|
938 | =item L<AnyEvent::DNS> |
|
|
939 | |
|
|
940 | Provides rich asynchronous DNS resolver capabilities. |
|
|
941 | |
|
|
942 | =item L<AnyEvent::HTTP> |
|
|
943 | |
|
|
944 | A simple-to-use HTTP library that is capable of making a lot of concurrent |
|
|
945 | HTTP requests. |
|
|
946 | |
|
|
947 | =item L<AnyEvent::HTTPD> |
|
|
948 | |
|
|
949 | Provides a simple web application server framework. |
|
|
950 | |
|
|
951 | =item L<AnyEvent::FastPing> |
|
|
952 | |
|
|
953 | The fastest ping in the west. |
|
|
954 | |
|
|
955 | =item L<AnyEvent::DBI> |
|
|
956 | |
|
|
957 | Executes L<DBI> requests asynchronously in a proxy process. |
|
|
958 | |
|
|
959 | =item L<AnyEvent::AIO> |
|
|
960 | |
|
|
961 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
962 | programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent |
|
|
963 | together. |
|
|
964 | |
|
|
965 | =item L<AnyEvent::BDB> |
|
|
966 | |
|
|
967 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses |
|
|
968 | L<BDB> and AnyEvent together. |
|
|
969 | |
|
|
970 | =item L<AnyEvent::GPSD> |
|
|
971 | |
|
|
972 | A non-blocking interface to gpsd, a daemon delivering GPS information. |
|
|
973 | |
|
|
974 | =item L<AnyEvent::IRC> |
|
|
975 | |
|
|
976 | AnyEvent based IRC client module family (replacing the older Net::IRC3). |
|
|
977 | |
|
|
978 | =item L<AnyEvent::XMPP> |
|
|
979 | |
|
|
980 | AnyEvent based XMPP (Jabber protocol) module family (replacing the older |
|
|
981 | Net::XMPP2>. |
|
|
982 | |
|
|
983 | =item L<AnyEvent::IGS> |
|
|
984 | |
|
|
985 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
986 | L<App::IGS>). |
|
|
987 | |
|
|
988 | =item L<Net::FCP> |
|
|
989 | |
|
|
990 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
991 | of AnyEvent. |
|
|
992 | |
|
|
993 | =item L<Event::ExecFlow> |
|
|
994 | |
|
|
995 | High level API for event-based execution flow control. |
|
|
996 | |
|
|
997 | =item L<Coro> |
|
|
998 | |
|
|
999 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
1000 | |
|
|
1001 | =back |
|
|
1002 | |
65 | =cut |
1003 | =cut |
66 | |
1004 | |
67 | package AnyEvent; |
1005 | package AnyEvent; |
68 | |
1006 | |
69 | no warnings; |
1007 | no warnings; |
70 | use strict 'vars'; |
1008 | use strict qw(vars subs); |
|
|
1009 | |
71 | use Carp; |
1010 | use Carp; |
72 | |
1011 | |
73 | our $VERSION = '1.02'; |
1012 | our $VERSION = 4.801; |
74 | our $MODEL; |
1013 | our $MODEL; |
75 | |
1014 | |
76 | our $AUTOLOAD; |
1015 | our $AUTOLOAD; |
77 | our @ISA; |
1016 | our @ISA; |
78 | |
1017 | |
|
|
1018 | our @REGISTRY; |
|
|
1019 | |
|
|
1020 | our $WIN32; |
|
|
1021 | |
|
|
1022 | BEGIN { |
|
|
1023 | eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }"; |
|
|
1024 | eval "sub TAINT(){ " . (${^TAINT}*1) . " }"; |
|
|
1025 | |
|
|
1026 | delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} |
|
|
1027 | if ${^TAINT}; |
|
|
1028 | } |
|
|
1029 | |
79 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
1030 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
80 | |
1031 | |
81 | our @REGISTRY; |
1032 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
|
|
1033 | |
|
|
1034 | { |
|
|
1035 | my $idx; |
|
|
1036 | $PROTOCOL{$_} = ++$idx |
|
|
1037 | for reverse split /\s*,\s*/, |
|
|
1038 | $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
1039 | } |
82 | |
1040 | |
83 | my @models = ( |
1041 | my @models = ( |
84 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
1042 | [EV:: => AnyEvent::Impl::EV::], |
85 | [Event:: => AnyEvent::Impl::Event::], |
1043 | [Event:: => AnyEvent::Impl::Event::], |
86 | [Glib:: => AnyEvent::Impl::Glib::], |
1044 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
1045 | # everything below here will not be autoprobed |
|
|
1046 | # as the pureperl backend should work everywhere |
|
|
1047 | # and is usually faster |
|
|
1048 | [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers |
|
|
1049 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
1050 | [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles |
|
|
1051 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
|
|
1052 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
87 | [Tk:: => AnyEvent::Impl::Tk::], |
1053 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
1054 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
1055 | # IO::Async is just too broken - we would need workarounds for its |
|
|
1056 | # byzantine signal and broken child handling, among others. |
|
|
1057 | # IO::Async is rather hard to detect, as it doesn't have any |
|
|
1058 | # obvious default class. |
|
|
1059 | # [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program |
|
|
1060 | # [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program |
|
|
1061 | # [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program |
88 | ); |
1062 | ); |
89 | |
1063 | |
90 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY); |
1064 | our %method = map +($_ => 1), |
|
|
1065 | qw(io timer time now now_update signal child idle condvar one_event DESTROY); |
91 | |
1066 | |
92 | sub AUTOLOAD { |
1067 | our @post_detect; |
93 | $AUTOLOAD =~ s/.*://; |
|
|
94 | |
1068 | |
95 | $method{$AUTOLOAD} |
1069 | sub post_detect(&) { |
96 | or croak "$AUTOLOAD: not a valid method for AnyEvent objects"; |
1070 | my ($cb) = @_; |
97 | |
1071 | |
|
|
1072 | if ($MODEL) { |
|
|
1073 | $cb->(); |
|
|
1074 | |
|
|
1075 | 1 |
|
|
1076 | } else { |
|
|
1077 | push @post_detect, $cb; |
|
|
1078 | |
|
|
1079 | defined wantarray |
|
|
1080 | ? bless \$cb, "AnyEvent::Util::postdetect" |
|
|
1081 | : () |
|
|
1082 | } |
|
|
1083 | } |
|
|
1084 | |
|
|
1085 | sub AnyEvent::Util::postdetect::DESTROY { |
|
|
1086 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
1087 | } |
|
|
1088 | |
|
|
1089 | sub detect() { |
98 | unless ($MODEL) { |
1090 | unless ($MODEL) { |
|
|
1091 | no strict 'refs'; |
|
|
1092 | local $SIG{__DIE__}; |
|
|
1093 | |
|
|
1094 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
1095 | my $model = "AnyEvent::Impl::$1"; |
|
|
1096 | if (eval "require $model") { |
|
|
1097 | $MODEL = $model; |
|
|
1098 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
1099 | } else { |
|
|
1100 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
1101 | } |
|
|
1102 | } |
|
|
1103 | |
99 | # check for already loaded models |
1104 | # check for already loaded models |
|
|
1105 | unless ($MODEL) { |
100 | for (@REGISTRY, @models) { |
1106 | for (@REGISTRY, @models) { |
101 | my ($package, $model) = @$_; |
1107 | my ($package, $model) = @$_; |
102 | if (${"$package\::VERSION"} > 0) { |
1108 | if (${"$package\::VERSION"} > 0) { |
103 | if (eval "require $model") { |
1109 | if (eval "require $model") { |
104 | $MODEL = $model; |
1110 | $MODEL = $model; |
105 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
1111 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
106 | last; |
1112 | last; |
|
|
1113 | } |
107 | } |
1114 | } |
108 | } |
1115 | } |
|
|
1116 | |
|
|
1117 | unless ($MODEL) { |
|
|
1118 | # try to load a model |
|
|
1119 | |
|
|
1120 | for (@REGISTRY, @models) { |
|
|
1121 | my ($package, $model) = @$_; |
|
|
1122 | if (eval "require $package" |
|
|
1123 | and ${"$package\::VERSION"} > 0 |
|
|
1124 | and eval "require $model") { |
|
|
1125 | $MODEL = $model; |
|
|
1126 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
|
|
1127 | last; |
|
|
1128 | } |
|
|
1129 | } |
|
|
1130 | |
|
|
1131 | $MODEL |
|
|
1132 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n"; |
|
|
1133 | } |
109 | } |
1134 | } |
110 | |
1135 | |
111 | unless ($MODEL) { |
1136 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
112 | # try to load a model |
|
|
113 | |
1137 | |
114 | for (@REGISTRY, @models) { |
1138 | unshift @ISA, $MODEL; |
115 | my ($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 | |
1139 | |
|
|
1140 | require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT}; |
|
|
1141 | |
|
|
1142 | (shift @post_detect)->() while @post_detect; |
|
|
1143 | } |
|
|
1144 | |
123 | $MODEL |
1145 | $MODEL |
124 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk."; |
1146 | } |
|
|
1147 | |
|
|
1148 | sub AUTOLOAD { |
|
|
1149 | (my $func = $AUTOLOAD) =~ s/.*://; |
|
|
1150 | |
|
|
1151 | $method{$func} |
|
|
1152 | or croak "$func: not a valid method for AnyEvent objects"; |
|
|
1153 | |
|
|
1154 | detect unless $MODEL; |
|
|
1155 | |
|
|
1156 | my $class = shift; |
|
|
1157 | $class->$func (@_); |
|
|
1158 | } |
|
|
1159 | |
|
|
1160 | # utility function to dup a filehandle. this is used by many backends |
|
|
1161 | # to support binding more than one watcher per filehandle (they usually |
|
|
1162 | # allow only one watcher per fd, so we dup it to get a different one). |
|
|
1163 | sub _dupfh($$;$$) { |
|
|
1164 | my ($poll, $fh, $r, $w) = @_; |
|
|
1165 | |
|
|
1166 | # cygwin requires the fh mode to be matching, unix doesn't |
|
|
1167 | my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">"); |
|
|
1168 | |
|
|
1169 | open my $fh2, "$mode&", $fh |
|
|
1170 | or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,"; |
|
|
1171 | |
|
|
1172 | # we assume CLOEXEC is already set by perl in all important cases |
|
|
1173 | |
|
|
1174 | ($fh2, $rw) |
|
|
1175 | } |
|
|
1176 | |
|
|
1177 | package AnyEvent::Base; |
|
|
1178 | |
|
|
1179 | # default implementations for many methods |
|
|
1180 | |
|
|
1181 | BEGIN { |
|
|
1182 | if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { |
|
|
1183 | *_time = \&Time::HiRes::time; |
|
|
1184 | # if (eval "use POSIX (); (POSIX::times())... |
|
|
1185 | } else { |
|
|
1186 | *_time = sub { time }; # epic fail |
|
|
1187 | } |
|
|
1188 | } |
|
|
1189 | |
|
|
1190 | sub time { _time } |
|
|
1191 | sub now { _time } |
|
|
1192 | sub now_update { } |
|
|
1193 | |
|
|
1194 | # default implementation for ->condvar |
|
|
1195 | |
|
|
1196 | sub condvar { |
|
|
1197 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" |
|
|
1198 | } |
|
|
1199 | |
|
|
1200 | # default implementation for ->signal |
|
|
1201 | |
|
|
1202 | our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); |
|
|
1203 | |
|
|
1204 | sub _signal_exec { |
|
|
1205 | sysread $SIGPIPE_R, my $dummy, 4; |
|
|
1206 | |
|
|
1207 | while (%SIG_EV) { |
|
|
1208 | for (keys %SIG_EV) { |
|
|
1209 | delete $SIG_EV{$_}; |
|
|
1210 | $_->() for values %{ $SIG_CB{$_} || {} }; |
125 | } |
1211 | } |
126 | } |
1212 | } |
|
|
1213 | } |
127 | |
1214 | |
128 | @ISA = $MODEL; |
1215 | sub signal { |
|
|
1216 | my (undef, %arg) = @_; |
129 | |
1217 | |
|
|
1218 | unless ($SIGPIPE_R) { |
|
|
1219 | require Fcntl; |
|
|
1220 | |
|
|
1221 | if (AnyEvent::WIN32) { |
|
|
1222 | require AnyEvent::Util; |
|
|
1223 | |
|
|
1224 | ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe (); |
|
|
1225 | AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R; |
|
|
1226 | AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case |
|
|
1227 | } else { |
|
|
1228 | pipe $SIGPIPE_R, $SIGPIPE_W; |
|
|
1229 | fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R; |
|
|
1230 | fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case |
|
|
1231 | |
|
|
1232 | # not strictly required, as $^F is normally 2, but let's make sure... |
|
|
1233 | fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; |
|
|
1234 | fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; |
|
|
1235 | } |
|
|
1236 | |
|
|
1237 | $SIGPIPE_R |
|
|
1238 | or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; |
|
|
1239 | |
|
|
1240 | $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec); |
|
|
1241 | } |
|
|
1242 | |
|
|
1243 | my $signal = uc $arg{signal} |
|
|
1244 | or Carp::croak "required option 'signal' is missing"; |
|
|
1245 | |
|
|
1246 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
|
|
1247 | $SIG{$signal} ||= sub { |
|
|
1248 | local $!; |
|
|
1249 | syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV; |
|
|
1250 | undef $SIG_EV{$signal}; |
|
|
1251 | }; |
|
|
1252 | |
|
|
1253 | bless [$signal, $arg{cb}], "AnyEvent::Base::signal" |
|
|
1254 | } |
|
|
1255 | |
|
|
1256 | sub AnyEvent::Base::signal::DESTROY { |
|
|
1257 | my ($signal, $cb) = @{$_[0]}; |
|
|
1258 | |
|
|
1259 | delete $SIG_CB{$signal}{$cb}; |
|
|
1260 | |
|
|
1261 | # delete doesn't work with older perls - they then |
|
|
1262 | # print weird messages, or just unconditionally exit |
|
|
1263 | # instead of getting the default action. |
|
|
1264 | undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; |
|
|
1265 | } |
|
|
1266 | |
|
|
1267 | # default implementation for ->child |
|
|
1268 | |
|
|
1269 | our %PID_CB; |
|
|
1270 | our $CHLD_W; |
|
|
1271 | our $CHLD_DELAY_W; |
|
|
1272 | our $WNOHANG; |
|
|
1273 | |
|
|
1274 | sub _sigchld { |
|
|
1275 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
|
|
1276 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
|
|
1277 | (values %{ $PID_CB{0} || {} }); |
|
|
1278 | } |
|
|
1279 | } |
|
|
1280 | |
|
|
1281 | sub child { |
|
|
1282 | my (undef, %arg) = @_; |
|
|
1283 | |
|
|
1284 | defined (my $pid = $arg{pid} + 0) |
|
|
1285 | or Carp::croak "required option 'pid' is missing"; |
|
|
1286 | |
|
|
1287 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
|
|
1288 | |
|
|
1289 | $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; |
|
|
1290 | |
|
|
1291 | unless ($CHLD_W) { |
|
|
1292 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
|
|
1293 | # child could be a zombie already, so make at least one round |
|
|
1294 | &_sigchld; |
|
|
1295 | } |
|
|
1296 | |
|
|
1297 | bless [$pid, $arg{cb}], "AnyEvent::Base::child" |
|
|
1298 | } |
|
|
1299 | |
|
|
1300 | sub AnyEvent::Base::child::DESTROY { |
|
|
1301 | my ($pid, $cb) = @{$_[0]}; |
|
|
1302 | |
|
|
1303 | delete $PID_CB{$pid}{$cb}; |
|
|
1304 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
|
|
1305 | |
|
|
1306 | undef $CHLD_W unless keys %PID_CB; |
|
|
1307 | } |
|
|
1308 | |
|
|
1309 | # idle emulation is done by simply using a timer, regardless |
|
|
1310 | # of whether the process is idle or not, and not letting |
|
|
1311 | # the callback use more than 50% of the time. |
|
|
1312 | sub idle { |
|
|
1313 | my (undef, %arg) = @_; |
|
|
1314 | |
|
|
1315 | my ($cb, $w, $rcb) = $arg{cb}; |
|
|
1316 | |
|
|
1317 | $rcb = sub { |
|
|
1318 | if ($cb) { |
|
|
1319 | $w = _time; |
|
|
1320 | &$cb; |
|
|
1321 | $w = _time - $w; |
|
|
1322 | |
|
|
1323 | # never use more then 50% of the time for the idle watcher, |
|
|
1324 | # within some limits |
|
|
1325 | $w = 0.0001 if $w < 0.0001; |
|
|
1326 | $w = 5 if $w > 5; |
|
|
1327 | |
|
|
1328 | $w = AnyEvent->timer (after => $w, cb => $rcb); |
|
|
1329 | } else { |
|
|
1330 | # clean up... |
|
|
1331 | undef $w; |
|
|
1332 | undef $rcb; |
|
|
1333 | } |
|
|
1334 | }; |
|
|
1335 | |
|
|
1336 | $w = AnyEvent->timer (after => 0.05, cb => $rcb); |
|
|
1337 | |
|
|
1338 | bless \\$cb, "AnyEvent::Base::idle" |
|
|
1339 | } |
|
|
1340 | |
|
|
1341 | sub AnyEvent::Base::idle::DESTROY { |
|
|
1342 | undef $${$_[0]}; |
|
|
1343 | } |
|
|
1344 | |
|
|
1345 | package AnyEvent::CondVar; |
|
|
1346 | |
|
|
1347 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
1348 | |
|
|
1349 | package AnyEvent::CondVar::Base; |
|
|
1350 | |
|
|
1351 | use overload |
|
|
1352 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
1353 | fallback => 1; |
|
|
1354 | |
|
|
1355 | sub _send { |
|
|
1356 | # nop |
|
|
1357 | } |
|
|
1358 | |
|
|
1359 | sub send { |
130 | my $class = shift; |
1360 | my $cv = shift; |
131 | $class->$AUTOLOAD (@_); |
1361 | $cv->{_ae_sent} = [@_]; |
|
|
1362 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
1363 | $cv->_send; |
132 | } |
1364 | } |
|
|
1365 | |
|
|
1366 | sub croak { |
|
|
1367 | $_[0]{_ae_croak} = $_[1]; |
|
|
1368 | $_[0]->send; |
|
|
1369 | } |
|
|
1370 | |
|
|
1371 | sub ready { |
|
|
1372 | $_[0]{_ae_sent} |
|
|
1373 | } |
|
|
1374 | |
|
|
1375 | sub _wait { |
|
|
1376 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
1377 | } |
|
|
1378 | |
|
|
1379 | sub recv { |
|
|
1380 | $_[0]->_wait; |
|
|
1381 | |
|
|
1382 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
1383 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
1384 | } |
|
|
1385 | |
|
|
1386 | sub cb { |
|
|
1387 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
1388 | $_[0]{_ae_cb} |
|
|
1389 | } |
|
|
1390 | |
|
|
1391 | sub begin { |
|
|
1392 | ++$_[0]{_ae_counter}; |
|
|
1393 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
1394 | } |
|
|
1395 | |
|
|
1396 | sub end { |
|
|
1397 | return if --$_[0]{_ae_counter}; |
|
|
1398 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
1399 | } |
|
|
1400 | |
|
|
1401 | # undocumented/compatibility with pre-3.4 |
|
|
1402 | *broadcast = \&send; |
|
|
1403 | *wait = \&_wait; |
|
|
1404 | |
|
|
1405 | =head1 ERROR AND EXCEPTION HANDLING |
|
|
1406 | |
|
|
1407 | In general, AnyEvent does not do any error handling - it relies on the |
|
|
1408 | caller to do that if required. The L<AnyEvent::Strict> module (see also |
|
|
1409 | the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict |
|
|
1410 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
1411 | development. |
|
|
1412 | |
|
|
1413 | As for exception handling (i.e. runtime errors and exceptions thrown while |
|
|
1414 | executing a callback), this is not only highly event-loop specific, but |
|
|
1415 | also not in any way wrapped by this module, as this is the job of the main |
|
|
1416 | program. |
|
|
1417 | |
|
|
1418 | The pure perl event loop simply re-throws the exception (usually |
|
|
1419 | within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<< |
|
|
1420 | $Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and |
|
|
1421 | so on. |
|
|
1422 | |
|
|
1423 | =head1 ENVIRONMENT VARIABLES |
|
|
1424 | |
|
|
1425 | The following environment variables are used by this module or its |
|
|
1426 | submodules. |
|
|
1427 | |
|
|
1428 | Note that AnyEvent will remove I<all> environment variables starting with |
|
|
1429 | C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is |
|
|
1430 | enabled. |
|
|
1431 | |
|
|
1432 | =over 4 |
|
|
1433 | |
|
|
1434 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1435 | |
|
|
1436 | By default, AnyEvent will be completely silent except in fatal |
|
|
1437 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1438 | talkative. |
|
|
1439 | |
|
|
1440 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1441 | conditions, such as not being able to load the event model specified by |
|
|
1442 | C<PERL_ANYEVENT_MODEL>. |
|
|
1443 | |
|
|
1444 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1445 | model it chooses. |
|
|
1446 | |
|
|
1447 | =item C<PERL_ANYEVENT_STRICT> |
|
|
1448 | |
|
|
1449 | AnyEvent does not do much argument checking by default, as thorough |
|
|
1450 | argument checking is very costly. Setting this variable to a true value |
|
|
1451 | will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly |
|
|
1452 | check the arguments passed to most method calls. If it finds any problems, |
|
|
1453 | it will croak. |
|
|
1454 | |
|
|
1455 | In other words, enables "strict" mode. |
|
|
1456 | |
|
|
1457 | Unlike C<use strict>, it is definitely recommended to keep it off in |
|
|
1458 | production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while |
|
|
1459 | developing programs can be very useful, however. |
|
|
1460 | |
|
|
1461 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1462 | |
|
|
1463 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1464 | auto detection and -probing kicks in. It must be a string consisting |
|
|
1465 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1466 | and the resulting module name is loaded and if the load was successful, |
|
|
1467 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1468 | auto detection and -probing. |
|
|
1469 | |
|
|
1470 | This functionality might change in future versions. |
|
|
1471 | |
|
|
1472 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1473 | could start your program like this: |
|
|
1474 | |
|
|
1475 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1476 | |
|
|
1477 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1478 | |
|
|
1479 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1480 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1481 | of auto probing). |
|
|
1482 | |
|
|
1483 | Must be set to a comma-separated list of protocols or address families, |
|
|
1484 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1485 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1486 | list. |
|
|
1487 | |
|
|
1488 | This variable can effectively be used for denial-of-service attacks |
|
|
1489 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1490 | small, as the program has to handle conenction and other failures anyways. |
|
|
1491 | |
|
|
1492 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1493 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1494 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1495 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1496 | IPv6, but prefer IPv6 over IPv4. |
|
|
1497 | |
|
|
1498 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1499 | |
|
|
1500 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1501 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1502 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1503 | default. |
|
|
1504 | |
|
|
1505 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1506 | EDNS0 in its DNS requests. |
|
|
1507 | |
|
|
1508 | =item C<PERL_ANYEVENT_MAX_FORKS> |
|
|
1509 | |
|
|
1510 | The maximum number of child processes that C<AnyEvent::Util::fork_call> |
|
|
1511 | will create in parallel. |
|
|
1512 | |
|
|
1513 | =item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS> |
|
|
1514 | |
|
|
1515 | The default value for the C<max_outstanding> parameter for the default DNS |
|
|
1516 | resolver - this is the maximum number of parallel DNS requests that are |
|
|
1517 | sent to the DNS server. |
|
|
1518 | |
|
|
1519 | =item C<PERL_ANYEVENT_RESOLV_CONF> |
|
|
1520 | |
|
|
1521 | The file to use instead of F</etc/resolv.conf> (or OS-specific |
|
|
1522 | configuration) in the default resolver. When set to the empty string, no |
|
|
1523 | default config will be used. |
|
|
1524 | |
|
|
1525 | =item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>. |
|
|
1526 | |
|
|
1527 | When neither C<ca_file> nor C<ca_path> was specified during |
|
|
1528 | L<AnyEvent::TLS> context creation, and either of these environment |
|
|
1529 | variables exist, they will be used to specify CA certificate locations |
|
|
1530 | instead of a system-dependent default. |
133 | |
1531 | |
134 | =back |
1532 | =back |
135 | |
1533 | |
136 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1534 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1535 | |
|
|
1536 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
1537 | a module. This section is only of use to event loop authors who want to |
|
|
1538 | provide AnyEvent compatibility. |
137 | |
1539 | |
138 | If you need to support another event library which isn't directly |
1540 | 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 |
1541 | supported by AnyEvent, you can supply your own interface to it by |
140 | pushing, before the first watcher gets created, the package name of |
1542 | 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 |
1543 | 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 |
1544 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
143 | AnyEvent. |
1545 | AnyEvent, so it is reasonably cheap. |
144 | |
1546 | |
145 | Example: |
1547 | Example: |
146 | |
1548 | |
147 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
1549 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
148 | |
1550 | |
149 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
1551 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
150 | package/class when it finds the C<urxvt> package/module is loaded. When |
1552 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
1553 | |
151 | AnyEvent is loaded and asked to find a suitable event model, it will |
1554 | When AnyEvent is loaded and asked to find a suitable event model, it |
152 | first check for the presence of urxvt. |
1555 | will first check for the presence of urxvt by trying to C<use> the |
|
|
1556 | C<urxvt::anyevent> module. |
153 | |
1557 | |
154 | The class should prove implementations for all watcher types (see |
1558 | The class should provide implementations for all watcher types. See |
155 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
1559 | 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 |
1560 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
157 | AnyEvent::Impl::Glib> to see the sources). |
1561 | see the sources. |
158 | |
1562 | |
|
|
1563 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
1564 | provide suitable (hopefully) replacements. |
|
|
1565 | |
159 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
1566 | 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 |
1567 | 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 |
1568 | 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 |
1569 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
163 | I<rxvt-unicode> distribution. |
1570 | I<rxvt-unicode> distribution. |
164 | |
1571 | |
165 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
1572 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
166 | condition variables: code blocking while waiting for a condition will |
1573 | condition variables: code blocking while waiting for a condition will |
167 | C<die>. This still works with most modules/usages, and blocking calls must |
1574 | C<die>. This still works with most modules/usages, and blocking calls must |
168 | not be in an interactive appliation, so it makes sense. |
1575 | not be done in an interactive application, so it makes sense. |
169 | |
1576 | |
170 | =head1 ENVIRONMENT VARIABLES |
|
|
171 | |
|
|
172 | The following environment variables are used by this module: |
|
|
173 | |
|
|
174 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
|
|
175 | model gets used. |
|
|
176 | |
|
|
177 | =head1 EXAMPLE |
1577 | =head1 EXAMPLE PROGRAM |
178 | |
1578 | |
179 | The following program uses an io watcher to read data from stdin, a timer |
1579 | 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 |
1580 | to display a message once per second, and a condition variable to quit the |
181 | when the user enters quit: |
1581 | program when the user enters quit: |
182 | |
1582 | |
183 | use AnyEvent; |
1583 | use AnyEvent; |
184 | |
1584 | |
185 | my $cv = AnyEvent->condvar; |
1585 | my $cv = AnyEvent->condvar; |
186 | |
1586 | |
187 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
1587 | my $io_watcher = AnyEvent->io ( |
|
|
1588 | fh => \*STDIN, |
|
|
1589 | poll => 'r', |
|
|
1590 | cb => sub { |
188 | warn "io event <$_[0]>\n"; # will always output <r> |
1591 | warn "io event <$_[0]>\n"; # will always output <r> |
189 | chomp (my $input = <STDIN>); # read a line |
1592 | chomp (my $input = <STDIN>); # read a line |
190 | warn "read: $input\n"; # output what has been read |
1593 | warn "read: $input\n"; # output what has been read |
191 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1594 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
|
|
1595 | }, |
192 | }); |
1596 | ); |
193 | |
1597 | |
194 | my $time_watcher; # can only be used once |
1598 | my $time_watcher; # can only be used once |
195 | |
1599 | |
196 | sub new_timer { |
1600 | sub new_timer { |
197 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1601 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
200 | }); |
1604 | }); |
201 | } |
1605 | } |
202 | |
1606 | |
203 | new_timer; # create first timer |
1607 | new_timer; # create first timer |
204 | |
1608 | |
205 | $cv->wait; # wait until user enters /^q/i |
1609 | $cv->recv; # wait until user enters /^q/i |
206 | |
1610 | |
207 | =head1 REAL-WORLD EXAMPLE |
1611 | =head1 REAL-WORLD EXAMPLE |
208 | |
1612 | |
209 | Consider the L<Net::FCP> module. It features (among others) the following |
1613 | 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: |
1614 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
260 | syswrite $txn->{fh}, $txn->{request} |
1664 | syswrite $txn->{fh}, $txn->{request} |
261 | or die "connection or write error"; |
1665 | or die "connection or write error"; |
262 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1666 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
263 | |
1667 | |
264 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1668 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
265 | result and signals any possible waiters that the request ahs finished: |
1669 | result and signals any possible waiters that the request has finished: |
266 | |
1670 | |
267 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1671 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
268 | |
1672 | |
269 | if (end-of-file or data complete) { |
1673 | if (end-of-file or data complete) { |
270 | $txn->{result} = $txn->{buf}; |
1674 | $txn->{result} = $txn->{buf}; |
271 | $txn->{finished}->broadcast; |
1675 | $txn->{finished}->send; |
272 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1676 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
273 | } |
1677 | } |
274 | |
1678 | |
275 | The C<result> method, finally, just waits for the finished signal (if the |
1679 | 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 |
1680 | request was already finished, it doesn't wait, of course, and returns the |
277 | data: |
1681 | data: |
278 | |
1682 | |
279 | $txn->{finished}->wait; |
1683 | $txn->{finished}->recv; |
280 | return $txn->{result}; |
1684 | return $txn->{result}; |
281 | |
1685 | |
282 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1686 | The actual code goes further and collects all errors (C<die>s, exceptions) |
283 | that occured during request processing. The C<result> method detects |
1687 | that occurred during request processing. The C<result> method detects |
284 | wether an exception as thrown (it is stored inside the $txn object) |
1688 | whether an exception as thrown (it is stored inside the $txn object) |
285 | and just throws the exception, which means connection errors and other |
1689 | 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 |
1690 | problems get reported tot he code that tries to use the result, not in a |
287 | random callback. |
1691 | random callback. |
288 | |
1692 | |
289 | All of this enables the following usage styles: |
1693 | All of this enables the following usage styles: |
290 | |
1694 | |
291 | 1. Blocking: |
1695 | 1. Blocking: |
292 | |
1696 | |
293 | my $data = $fcp->client_get ($url); |
1697 | my $data = $fcp->client_get ($url); |
294 | |
1698 | |
295 | 2. Blocking, but parallelizing: |
1699 | 2. Blocking, but running in parallel: |
296 | |
1700 | |
297 | my @datas = map $_->result, |
1701 | my @datas = map $_->result, |
298 | map $fcp->txn_client_get ($_), |
1702 | map $fcp->txn_client_get ($_), |
299 | @urls; |
1703 | @urls; |
300 | |
1704 | |
301 | Both blocking examples work without the module user having to know |
1705 | Both blocking examples work without the module user having to know |
302 | anything about events. |
1706 | anything about events. |
303 | |
1707 | |
304 | 3a. Event-based in a main program, using any support Event module: |
1708 | 3a. Event-based in a main program, using any supported event module: |
305 | |
1709 | |
306 | use Event; |
1710 | use EV; |
307 | |
1711 | |
308 | $fcp->txn_client_get ($url)->cb (sub { |
1712 | $fcp->txn_client_get ($url)->cb (sub { |
309 | my $txn = shift; |
1713 | my $txn = shift; |
310 | my $data = $txn->result; |
1714 | my $data = $txn->result; |
311 | ... |
1715 | ... |
312 | }); |
1716 | }); |
313 | |
1717 | |
314 | Event::loop; |
1718 | EV::loop; |
315 | |
1719 | |
316 | 3b. The module user could use AnyEvent, too: |
1720 | 3b. The module user could use AnyEvent, too: |
317 | |
1721 | |
318 | use AnyEvent; |
1722 | use AnyEvent; |
319 | |
1723 | |
320 | my $quit = AnyEvent->condvar; |
1724 | my $quit = AnyEvent->condvar; |
321 | |
1725 | |
322 | $fcp->txn_client_get ($url)->cb (sub { |
1726 | $fcp->txn_client_get ($url)->cb (sub { |
323 | ... |
1727 | ... |
324 | $quit->broadcast; |
1728 | $quit->send; |
325 | }); |
1729 | }); |
326 | |
1730 | |
327 | $quit->wait; |
1731 | $quit->recv; |
|
|
1732 | |
|
|
1733 | |
|
|
1734 | =head1 BENCHMARKS |
|
|
1735 | |
|
|
1736 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1737 | over the event loops themselves and to give you an impression of the speed |
|
|
1738 | of various event loops I prepared some benchmarks. |
|
|
1739 | |
|
|
1740 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1741 | |
|
|
1742 | Here is a benchmark of various supported event models used natively and |
|
|
1743 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1744 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1745 | which it is), lets them fire exactly once and destroys them again. |
|
|
1746 | |
|
|
1747 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1748 | distribution. |
|
|
1749 | |
|
|
1750 | =head3 Explanation of the columns |
|
|
1751 | |
|
|
1752 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1753 | different event models feature vastly different performances, each event |
|
|
1754 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1755 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1756 | would probably take thousands of years if asked to process the same number |
|
|
1757 | of watchers as EV in this benchmark. |
|
|
1758 | |
|
|
1759 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1760 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1761 | and Perl-based overheads. |
|
|
1762 | |
|
|
1763 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1764 | takes to create a single watcher. The callback is a closure shared between |
|
|
1765 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1766 | and memory usage is not included in the figures. |
|
|
1767 | |
|
|
1768 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1769 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1770 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1771 | signal the end of this phase. |
|
|
1772 | |
|
|
1773 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1774 | watcher. |
|
|
1775 | |
|
|
1776 | =head3 Results |
|
|
1777 | |
|
|
1778 | name watchers bytes create invoke destroy comment |
|
|
1779 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
|
|
1780 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
|
|
1781 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
|
|
1782 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
|
|
1783 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
|
|
1784 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1785 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
|
|
1786 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
|
|
1787 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
|
|
1788 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
|
|
1789 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
|
|
1790 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
|
|
1791 | |
|
|
1792 | =head3 Discussion |
|
|
1793 | |
|
|
1794 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1795 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1796 | can never compete with an event loop that uses epoll when the number of |
|
|
1797 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1798 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1799 | boost. |
|
|
1800 | |
|
|
1801 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1802 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1803 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1804 | higher number of watchers at a disadvantage. |
|
|
1805 | |
|
|
1806 | To put the range of results into perspective, consider that on the |
|
|
1807 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1808 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1809 | cycles with POE. |
|
|
1810 | |
|
|
1811 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1812 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1813 | far less memory than any other event loop and is still faster than Event |
|
|
1814 | natively. |
|
|
1815 | |
|
|
1816 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1817 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1818 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1819 | adds very little overhead in itself. Like any select-based backend its |
|
|
1820 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1821 | them active), of course, but this was not subject of this benchmark. |
|
|
1822 | |
|
|
1823 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1824 | cost, but overall scores in on the third place. |
|
|
1825 | |
|
|
1826 | C<IO::Async> performs admirably well, about on par with C<Event>, even |
|
|
1827 | when using its pure perl backend. |
|
|
1828 | |
|
|
1829 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1830 | faster callback invocation and overall ends up in the same class as |
|
|
1831 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1832 | watchers increases the processing time by more than a factor of four, |
|
|
1833 | making it completely unusable when using larger numbers of watchers |
|
|
1834 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1835 | inefficiencies of C<poll> do not account for this). |
|
|
1836 | |
|
|
1837 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1838 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1839 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1840 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1841 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1842 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1843 | above). |
|
|
1844 | |
|
|
1845 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1846 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1847 | be tested because it wasn't working) shows abysmal performance and |
|
|
1848 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1849 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1850 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1851 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1852 | implementation. |
|
|
1853 | |
|
|
1854 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1855 | for the performance issues, though, as session creation overhead is |
|
|
1856 | small compared to execution of the state machine, which is coded pretty |
|
|
1857 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1858 | using multiple sessions is not a good approach, especially regarding |
|
|
1859 | memory usage, even the author of POE could not come up with a faster |
|
|
1860 | design). |
|
|
1861 | |
|
|
1862 | =head3 Summary |
|
|
1863 | |
|
|
1864 | =over 4 |
|
|
1865 | |
|
|
1866 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1867 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1868 | performance with or without AnyEvent. |
|
|
1869 | |
|
|
1870 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1871 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1872 | adds AnyEvent significant overhead. |
|
|
1873 | |
|
|
1874 | =item * You should avoid POE like the plague if you want performance or |
|
|
1875 | reasonable memory usage. |
|
|
1876 | |
|
|
1877 | =back |
|
|
1878 | |
|
|
1879 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1880 | |
|
|
1881 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1882 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1883 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1884 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1885 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1886 | |
|
|
1887 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1888 | are active at any one point (so there is a constant number of active |
|
|
1889 | fds for each loop iteration, but which fds these are is random). The |
|
|
1890 | timeout is reset each time something is read because that reflects how |
|
|
1891 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1892 | |
|
|
1893 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1894 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1895 | connections, most of which are idle at any one point in time. |
|
|
1896 | |
|
|
1897 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1898 | distribution. |
|
|
1899 | |
|
|
1900 | =head3 Explanation of the columns |
|
|
1901 | |
|
|
1902 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1903 | each server has a read and write socket end). |
|
|
1904 | |
|
|
1905 | I<create> is the time it takes to create a socket pair (which is |
|
|
1906 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1907 | |
|
|
1908 | I<request>, the most important value, is the time it takes to handle a |
|
|
1909 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1910 | it to another server. This includes deleting the old timeout and creating |
|
|
1911 | a new one that moves the timeout into the future. |
|
|
1912 | |
|
|
1913 | =head3 Results |
|
|
1914 | |
|
|
1915 | name sockets create request |
|
|
1916 | EV 20000 69.01 11.16 |
|
|
1917 | Perl 20000 73.32 35.87 |
|
|
1918 | IOAsync 20000 157.00 98.14 epoll |
|
|
1919 | IOAsync 20000 159.31 616.06 poll |
|
|
1920 | Event 20000 212.62 257.32 |
|
|
1921 | Glib 20000 651.16 1896.30 |
|
|
1922 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1923 | |
|
|
1924 | =head3 Discussion |
|
|
1925 | |
|
|
1926 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1927 | particular event loop. |
|
|
1928 | |
|
|
1929 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1930 | is relatively high, though. |
|
|
1931 | |
|
|
1932 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1933 | loops Event and Glib. |
|
|
1934 | |
|
|
1935 | IO::Async performs very well when using its epoll backend, and still quite |
|
|
1936 | good compared to Glib when using its pure perl backend. |
|
|
1937 | |
|
|
1938 | Event suffers from high setup time as well (look at its code and you will |
|
|
1939 | understand why). Callback invocation also has a high overhead compared to |
|
|
1940 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1941 | uses select or poll in basically all documented configurations. |
|
|
1942 | |
|
|
1943 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1944 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1945 | |
|
|
1946 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1947 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1948 | it uses a C-based event loop in this case. |
|
|
1949 | |
|
|
1950 | =head3 Summary |
|
|
1951 | |
|
|
1952 | =over 4 |
|
|
1953 | |
|
|
1954 | =item * The pure perl implementation performs extremely well. |
|
|
1955 | |
|
|
1956 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1957 | |
|
|
1958 | =back |
|
|
1959 | |
|
|
1960 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1961 | |
|
|
1962 | While event loops should scale (and select-based ones do not...) even to |
|
|
1963 | large servers, most programs we (or I :) actually write have only a few |
|
|
1964 | I/O watchers. |
|
|
1965 | |
|
|
1966 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1967 | case, but it uses only eight "servers", of which three are active at any |
|
|
1968 | one time. This should reflect performance for a small server relatively |
|
|
1969 | well. |
|
|
1970 | |
|
|
1971 | The columns are identical to the previous table. |
|
|
1972 | |
|
|
1973 | =head3 Results |
|
|
1974 | |
|
|
1975 | name sockets create request |
|
|
1976 | EV 16 20.00 6.54 |
|
|
1977 | Perl 16 25.75 12.62 |
|
|
1978 | Event 16 81.27 35.86 |
|
|
1979 | Glib 16 32.63 15.48 |
|
|
1980 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1981 | |
|
|
1982 | =head3 Discussion |
|
|
1983 | |
|
|
1984 | The benchmark tries to test the performance of a typical small |
|
|
1985 | server. While knowing how various event loops perform is interesting, keep |
|
|
1986 | in mind that their overhead in this case is usually not as important, due |
|
|
1987 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1988 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1989 | them). |
|
|
1990 | |
|
|
1991 | EV is again fastest. |
|
|
1992 | |
|
|
1993 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1994 | loops Event and Glib, although the difference is too small to really |
|
|
1995 | matter. |
|
|
1996 | |
|
|
1997 | POE also performs much better in this case, but is is still far behind the |
|
|
1998 | others. |
|
|
1999 | |
|
|
2000 | =head3 Summary |
|
|
2001 | |
|
|
2002 | =over 4 |
|
|
2003 | |
|
|
2004 | =item * C-based event loops perform very well with small number of |
|
|
2005 | watchers, as the management overhead dominates. |
|
|
2006 | |
|
|
2007 | =back |
|
|
2008 | |
|
|
2009 | =head2 THE IO::Lambda BENCHMARK |
|
|
2010 | |
|
|
2011 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
2012 | could be misinterpreted to make AnyEvent look bad. In fact, the benchmark |
|
|
2013 | simply compares IO::Lambda with POE, and IO::Lambda looks better (which |
|
|
2014 | shouldn't come as a surprise to anybody). As such, the benchmark is |
|
|
2015 | fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't |
|
|
2016 | very optimal. But how would AnyEvent compare when used without the extra |
|
|
2017 | baggage? To explore this, I wrote the equivalent benchmark for AnyEvent. |
|
|
2018 | |
|
|
2019 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
2020 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
2021 | creates the next connection. This is a rather bad benchmark, as it doesn't |
|
|
2022 | test the efficiency of the framework or much non-blocking I/O, but it is a |
|
|
2023 | benchmark nevertheless. |
|
|
2024 | |
|
|
2025 | name runtime |
|
|
2026 | Lambda/select 0.330 sec |
|
|
2027 | + optimized 0.122 sec |
|
|
2028 | Lambda/AnyEvent 0.327 sec |
|
|
2029 | + optimized 0.138 sec |
|
|
2030 | Raw sockets/select 0.077 sec |
|
|
2031 | POE/select, components 0.662 sec |
|
|
2032 | POE/select, raw sockets 0.226 sec |
|
|
2033 | POE/select, optimized 0.404 sec |
|
|
2034 | |
|
|
2035 | AnyEvent/select/nb 0.085 sec |
|
|
2036 | AnyEvent/EV/nb 0.068 sec |
|
|
2037 | +state machine 0.134 sec |
|
|
2038 | |
|
|
2039 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
|
|
2040 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
2041 | defeating the purpose of an event-based solution. All of the newly |
|
|
2042 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
2043 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
2044 | resolver), so AnyEvent is at a disadvantage here, as non-blocking connects |
|
|
2045 | generally require a lot more bookkeeping and event handling than blocking |
|
|
2046 | connects (which involve a single syscall only). |
|
|
2047 | |
|
|
2048 | The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which |
|
|
2049 | offers similar expressive power as POE and IO::Lambda, using conventional |
|
|
2050 | Perl syntax. This means that both the echo server and the client are 100% |
|
|
2051 | non-blocking, further placing it at a disadvantage. |
|
|
2052 | |
|
|
2053 | As you can see, the AnyEvent + EV combination even beats the |
|
|
2054 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
|
|
2055 | backend easily beats IO::Lambda and POE. |
|
|
2056 | |
|
|
2057 | And even the 100% non-blocking version written using the high-level (and |
|
|
2058 | slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a |
|
|
2059 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
|
|
2060 | in a non-blocking way. |
|
|
2061 | |
|
|
2062 | The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and |
|
|
2063 | F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are |
|
|
2064 | part of the IO::lambda distribution and were used without any changes. |
|
|
2065 | |
|
|
2066 | |
|
|
2067 | =head1 SIGNALS |
|
|
2068 | |
|
|
2069 | AnyEvent currently installs handlers for these signals: |
|
|
2070 | |
|
|
2071 | =over 4 |
|
|
2072 | |
|
|
2073 | =item SIGCHLD |
|
|
2074 | |
|
|
2075 | A handler for C<SIGCHLD> is installed by AnyEvent's child watcher |
|
|
2076 | emulation for event loops that do not support them natively. Also, some |
|
|
2077 | event loops install a similar handler. |
|
|
2078 | |
|
|
2079 | If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will |
|
|
2080 | reset it to default, to avoid losing child exit statuses. |
|
|
2081 | |
|
|
2082 | =item SIGPIPE |
|
|
2083 | |
|
|
2084 | A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> |
|
|
2085 | when AnyEvent gets loaded. |
|
|
2086 | |
|
|
2087 | The rationale for this is that AnyEvent users usually do not really depend |
|
|
2088 | on SIGPIPE delivery (which is purely an optimisation for shell use, or |
|
|
2089 | badly-written programs), but C<SIGPIPE> can cause spurious and rare |
|
|
2090 | program exits as a lot of people do not expect C<SIGPIPE> when writing to |
|
|
2091 | some random socket. |
|
|
2092 | |
|
|
2093 | The rationale for installing a no-op handler as opposed to ignoring it is |
|
|
2094 | that this way, the handler will be restored to defaults on exec. |
|
|
2095 | |
|
|
2096 | Feel free to install your own handler, or reset it to defaults. |
|
|
2097 | |
|
|
2098 | =back |
|
|
2099 | |
|
|
2100 | =cut |
|
|
2101 | |
|
|
2102 | undef $SIG{CHLD} |
|
|
2103 | if $SIG{CHLD} eq 'IGNORE'; |
|
|
2104 | |
|
|
2105 | $SIG{PIPE} = sub { } |
|
|
2106 | unless defined $SIG{PIPE}; |
|
|
2107 | |
|
|
2108 | =head1 FORK |
|
|
2109 | |
|
|
2110 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
2111 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
2112 | calls. Only L<EV> is fully fork-aware. |
|
|
2113 | |
|
|
2114 | If you have to fork, you must either do so I<before> creating your first |
|
|
2115 | watcher OR you must not use AnyEvent at all in the child. |
|
|
2116 | |
|
|
2117 | |
|
|
2118 | =head1 SECURITY CONSIDERATIONS |
|
|
2119 | |
|
|
2120 | AnyEvent can be forced to load any event model via |
|
|
2121 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
2122 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
2123 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
2124 | will not be active when the program uses a different event model than |
|
|
2125 | specified in the variable. |
|
|
2126 | |
|
|
2127 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
2128 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
2129 | |
|
|
2130 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
2131 | |
|
|
2132 | use AnyEvent; |
|
|
2133 | |
|
|
2134 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
2135 | be used to probe what backend is used and gain other information (which is |
|
|
2136 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and |
|
|
2137 | $ENV{PERL_ANYEVENT_STRICT}. |
|
|
2138 | |
|
|
2139 | Note that AnyEvent will remove I<all> environment variables starting with |
|
|
2140 | C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is |
|
|
2141 | enabled. |
|
|
2142 | |
|
|
2143 | |
|
|
2144 | =head1 BUGS |
|
|
2145 | |
|
|
2146 | Perl 5.8 has numerous memleaks that sometimes hit this module and are hard |
|
|
2147 | to work around. If you suffer from memleaks, first upgrade to Perl 5.10 |
|
|
2148 | and check wether the leaks still show up. (Perl 5.10.0 has other annoying |
|
|
2149 | memleaks, such as leaking on C<map> and C<grep> but it is usually not as |
|
|
2150 | pronounced). |
|
|
2151 | |
328 | |
2152 | |
329 | =head1 SEE ALSO |
2153 | =head1 SEE ALSO |
330 | |
2154 | |
331 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
2155 | Utility functions: L<AnyEvent::Util>. |
332 | |
2156 | |
333 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
2157 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
|
|
2158 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
334 | |
2159 | |
335 | Nontrivial usage example: L<Net::FCP>. |
2160 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
|
|
2161 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
2162 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
2163 | L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>. |
336 | |
2164 | |
337 | =head1 |
2165 | Non-blocking file handles, sockets, TCP clients and |
|
|
2166 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>. |
|
|
2167 | |
|
|
2168 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
2169 | |
|
|
2170 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, |
|
|
2171 | L<Coro::Event>, |
|
|
2172 | |
|
|
2173 | Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>, |
|
|
2174 | L<AnyEvent::HTTP>. |
|
|
2175 | |
|
|
2176 | |
|
|
2177 | =head1 AUTHOR |
|
|
2178 | |
|
|
2179 | Marc Lehmann <schmorp@schmorp.de> |
|
|
2180 | http://home.schmorp.de/ |
338 | |
2181 | |
339 | =cut |
2182 | =cut |
340 | |
2183 | |
341 | 1 |
2184 | 1 |
342 | |
2185 | |