1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | AnyEvent - provide framework for multiple event loops |
3 | AnyEvent - provide framework for multiple event loops |
4 | |
4 | |
5 | Event, Coro, Glib, Tk, Perl - various supported event loops |
5 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
6 | |
6 | |
7 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
8 | |
8 | |
9 | use AnyEvent; |
9 | use AnyEvent; |
10 | |
10 | |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... }); |
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12 | |
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13 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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14 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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15 | |
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16 | print AnyEvent->now; # prints current event loop time |
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17 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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18 | |
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19 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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20 | |
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21 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
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22 | my ($pid, $status) = @_; |
12 | ... |
23 | ... |
13 | }); |
24 | }); |
14 | |
25 | |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
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16 | ... |
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17 | }); |
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18 | |
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19 | my $w = AnyEvent->condvar; # stores wether a condition was flagged |
26 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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27 | $w->send; # wake up current and all future recv's |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
28 | $w->recv; # enters "main loop" till $condvar gets ->send |
21 | $w->broadcast; # wake up current and all future wait's |
29 | # use a condvar in callback mode: |
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30 | $w->cb (sub { $_[0]->recv }); |
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31 | |
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32 | =head1 INTRODUCTION/TUTORIAL |
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33 | |
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34 | This manpage is mainly a reference manual. If you are interested |
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35 | in a tutorial or some gentle introduction, have a look at the |
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36 | L<AnyEvent::Intro> manpage. |
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37 | |
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38 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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39 | |
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40 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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41 | nowadays. So what is different about AnyEvent? |
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42 | |
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43 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
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44 | policy> and AnyEvent is I<small and efficient>. |
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45 | |
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46 | First and foremost, I<AnyEvent is not an event model> itself, it only |
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47 | interfaces to whatever event model the main program happens to use, in a |
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48 | pragmatic way. For event models and certain classes of immortals alike, |
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49 | the statement "there can only be one" is a bitter reality: In general, |
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50 | only one event loop can be active at the same time in a process. AnyEvent |
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51 | cannot change this, but it can hide the differences between those event |
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52 | loops. |
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53 | |
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54 | The goal of AnyEvent is to offer module authors the ability to do event |
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55 | programming (waiting for I/O or timer events) without subscribing to a |
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56 | religion, a way of living, and most importantly: without forcing your |
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57 | module users into the same thing by forcing them to use the same event |
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58 | model you use. |
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59 | |
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60 | For modules like POE or IO::Async (which is a total misnomer as it is |
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61 | actually doing all I/O I<synchronously>...), using them in your module is |
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62 | like joining a cult: After you joined, you are dependent on them and you |
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63 | cannot use anything else, as they are simply incompatible to everything |
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64 | that isn't them. What's worse, all the potential users of your |
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65 | module are I<also> forced to use the same event loop you use. |
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66 | |
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67 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
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68 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
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69 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if |
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70 | your module uses one of those, every user of your module has to use it, |
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71 | too. But if your module uses AnyEvent, it works transparently with all |
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72 | event models it supports (including stuff like IO::Async, as long as those |
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73 | use one of the supported event loops. It is trivial to add new event loops |
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74 | to AnyEvent, too, so it is future-proof). |
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75 | |
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76 | In addition to being free of having to use I<the one and only true event |
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77 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
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78 | modules, you get an enormous amount of code and strict rules you have to |
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79 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
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80 | offering the functionality that is necessary, in as thin as a wrapper as |
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81 | technically possible. |
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82 | |
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83 | Of course, AnyEvent comes with a big (and fully optional!) toolbox |
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84 | of useful functionality, such as an asynchronous DNS resolver, 100% |
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85 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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86 | such as Windows) and lots of real-world knowledge and workarounds for |
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87 | platform bugs and differences. |
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88 | |
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89 | Now, if you I<do want> lots of policy (this can arguably be somewhat |
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90 | useful) and you want to force your users to use the one and only event |
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91 | model, you should I<not> use this module. |
22 | |
92 | |
23 | =head1 DESCRIPTION |
93 | =head1 DESCRIPTION |
24 | |
94 | |
25 | L<AnyEvent> provides an identical interface to multiple event loops. This |
95 | L<AnyEvent> provides an identical interface to multiple event loops. This |
26 | allows module authors to utilise an event loop without forcing module |
96 | allows module authors to utilise an event loop without forcing module |
27 | users to use the same event loop (as only a single event loop can coexist |
97 | users to use the same event loop (as only a single event loop can coexist |
28 | peacefully at any one time). |
98 | peacefully at any one time). |
29 | |
99 | |
30 | The interface itself is vaguely similar but not identical to the Event |
100 | The interface itself is vaguely similar, but not identical to the L<Event> |
31 | module. |
101 | module. |
32 | |
102 | |
33 | On the first call of any method, the module tries to detect the currently |
103 | During the first call of any watcher-creation method, the module tries |
34 | loaded event loop by probing wether any of the following modules is |
104 | to detect the currently loaded event loop by probing whether one of the |
35 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
105 | following modules is already loaded: L<EV>, |
36 | used. If none is found, the module tries to load these modules in the |
106 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
37 | order given. The first one that could be successfully loaded will be |
107 | L<POE>. The first one found is used. If none are found, the module tries |
38 | used. If still none could be found, AnyEvent will fall back to a pure-perl |
108 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
39 | event loop, which is also not very efficient. |
109 | adaptor should always succeed) in the order given. The first one that can |
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110 | be successfully loaded will be used. If, after this, still none could be |
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111 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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112 | very efficient, but should work everywhere. |
40 | |
113 | |
41 | Because AnyEvent first checks for modules that are already loaded, loading |
114 | Because AnyEvent first checks for modules that are already loaded, loading |
42 | an Event model explicitly before first using AnyEvent will likely make |
115 | an event model explicitly before first using AnyEvent will likely make |
43 | that model the default. For example: |
116 | that model the default. For example: |
44 | |
117 | |
45 | use Tk; |
118 | use Tk; |
46 | use AnyEvent; |
119 | use AnyEvent; |
47 | |
120 | |
48 | # .. AnyEvent will likely default to Tk |
121 | # .. AnyEvent will likely default to Tk |
49 | |
122 | |
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123 | The I<likely> means that, if any module loads another event model and |
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124 | starts using it, all bets are off. Maybe you should tell their authors to |
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125 | use AnyEvent so their modules work together with others seamlessly... |
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126 | |
50 | The pure-perl implementation of AnyEvent is called |
127 | The pure-perl implementation of AnyEvent is called |
51 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
128 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
52 | explicitly. |
129 | explicitly and enjoy the high availability of that event loop :) |
53 | |
130 | |
54 | =head1 WATCHERS |
131 | =head1 WATCHERS |
55 | |
132 | |
56 | AnyEvent has the central concept of a I<watcher>, which is an object that |
133 | AnyEvent has the central concept of a I<watcher>, which is an object that |
57 | stores relevant data for each kind of event you are waiting for, such as |
134 | stores relevant data for each kind of event you are waiting for, such as |
58 | the callback to call, the filehandle to watch, etc. |
135 | the callback to call, the file handle to watch, etc. |
59 | |
136 | |
60 | These watchers are normal Perl objects with normal Perl lifetime. After |
137 | These watchers are normal Perl objects with normal Perl lifetime. After |
61 | creating a watcher it will immediately "watch" for events and invoke |
138 | creating a watcher it will immediately "watch" for events and invoke the |
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139 | callback when the event occurs (of course, only when the event model |
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140 | is in control). |
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141 | |
62 | the callback. To disable the watcher you have to destroy it (e.g. by |
142 | To disable the watcher you have to destroy it (e.g. by setting the |
63 | setting the variable that stores it to C<undef> or otherwise deleting all |
143 | variable you store it in to C<undef> or otherwise deleting all references |
64 | references to it). |
144 | to it). |
65 | |
145 | |
66 | All watchers are created by calling a method on the C<AnyEvent> class. |
146 | All watchers are created by calling a method on the C<AnyEvent> class. |
67 | |
147 | |
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148 | Many watchers either are used with "recursion" (repeating timers for |
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149 | example), or need to refer to their watcher object in other ways. |
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150 | |
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151 | An any way to achieve that is this pattern: |
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152 | |
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153 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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154 | # you can use $w here, for example to undef it |
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155 | undef $w; |
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156 | }); |
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157 | |
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158 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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159 | my variables are only visible after the statement in which they are |
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160 | declared. |
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161 | |
68 | =head2 IO WATCHERS |
162 | =head2 I/O WATCHERS |
69 | |
163 | |
70 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
164 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
71 | the following mandatory arguments: |
165 | with the following mandatory key-value pairs as arguments: |
72 | |
166 | |
73 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
167 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events |
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168 | (AnyEvent might or might not keep a reference to this file handle). C<poll> |
74 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
169 | must be a string that is either C<r> or C<w>, which creates a watcher |
75 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback |
170 | waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the |
76 | to invoke everytime the filehandle becomes ready. |
171 | callback to invoke each time the file handle becomes ready. |
77 | |
172 | |
78 | Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
173 | Although the callback might get passed parameters, their value and |
79 | a socket you can have one r + one w, not any more (limitation comes from |
174 | presence is undefined and you cannot rely on them. Portable AnyEvent |
80 | Tk - if you are sure you are not using Tk this limitation is gone). |
175 | callbacks cannot use arguments passed to I/O watcher callbacks. |
81 | |
176 | |
82 | Filehandles will be kept alive, so as long as the watcher exists, the |
177 | The I/O watcher might use the underlying file descriptor or a copy of it. |
83 | filehandle exists, too. |
178 | You must not close a file handle as long as any watcher is active on the |
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179 | underlying file descriptor. |
84 | |
180 | |
85 | Example: |
181 | Some event loops issue spurious readyness notifications, so you should |
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182 | always use non-blocking calls when reading/writing from/to your file |
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183 | handles. |
86 | |
184 | |
87 | # wait for readability of STDIN, then read a line and disable the watcher |
185 | Example: wait for readability of STDIN, then read a line and disable the |
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186 | watcher. |
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187 | |
88 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
188 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
89 | chomp (my $input = <STDIN>); |
189 | chomp (my $input = <STDIN>); |
90 | warn "read: $input\n"; |
190 | warn "read: $input\n"; |
91 | undef $w; |
191 | undef $w; |
92 | }); |
192 | }); |
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94 | =head2 TIME WATCHERS |
194 | =head2 TIME WATCHERS |
95 | |
195 | |
96 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
196 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
97 | method with the following mandatory arguments: |
197 | method with the following mandatory arguments: |
98 | |
198 | |
99 | C<after> after how many seconds (fractions are supported) should the timer |
199 | C<after> specifies after how many seconds (fractional values are |
100 | activate. C<cb> the callback to invoke. |
200 | supported) the callback should be invoked. C<cb> is the callback to invoke |
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201 | in that case. |
101 | |
202 | |
102 | The timer callback will be invoked at most once: if you want a repeating |
203 | Although the callback might get passed parameters, their value and |
103 | timer you have to create a new watcher (this is a limitation by both Tk |
204 | presence is undefined and you cannot rely on them. Portable AnyEvent |
104 | and Glib). |
205 | callbacks cannot use arguments passed to time watcher callbacks. |
105 | |
206 | |
106 | Example: |
207 | The callback will normally be invoked once only. If you specify another |
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208 | parameter, C<interval>, as a strictly positive number (> 0), then the |
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209 | callback will be invoked regularly at that interval (in fractional |
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210 | seconds) after the first invocation. If C<interval> is specified with a |
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211 | false value, then it is treated as if it were missing. |
107 | |
212 | |
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213 | The callback will be rescheduled before invoking the callback, but no |
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214 | attempt is done to avoid timer drift in most backends, so the interval is |
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215 | only approximate. |
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216 | |
108 | # fire an event after 7.7 seconds |
217 | Example: fire an event after 7.7 seconds. |
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218 | |
109 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
219 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
110 | warn "timeout\n"; |
220 | warn "timeout\n"; |
111 | }); |
221 | }); |
112 | |
222 | |
113 | # to cancel the timer: |
223 | # to cancel the timer: |
114 | undef $w |
224 | undef $w; |
115 | |
225 | |
116 | =head2 CONDITION WATCHERS |
226 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
117 | |
227 | |
118 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
228 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
119 | method without any arguments. |
229 | warn "timeout\n"; |
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230 | }; |
120 | |
231 | |
121 | A condition watcher watches for a condition - precisely that the C<< |
232 | =head3 TIMING ISSUES |
122 | ->broadcast >> method has been called. |
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123 | |
233 | |
124 | The watcher has only two methods: |
234 | There are two ways to handle timers: based on real time (relative, "fire |
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235 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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236 | o'clock"). |
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237 | |
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238 | While most event loops expect timers to specified in a relative way, they |
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239 | use absolute time internally. This makes a difference when your clock |
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240 | "jumps", for example, when ntp decides to set your clock backwards from |
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241 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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242 | fire "after" a second might actually take six years to finally fire. |
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243 | |
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244 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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245 | about these issues is L<EV>, which offers both relative (ev_timer, based |
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246 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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247 | timers. |
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248 | |
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249 | AnyEvent always prefers relative timers, if available, matching the |
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250 | AnyEvent API. |
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251 | |
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252 | AnyEvent has two additional methods that return the "current time": |
125 | |
253 | |
126 | =over 4 |
254 | =over 4 |
127 | |
255 | |
128 | =item $cv->wait |
256 | =item AnyEvent->time |
129 | |
257 | |
130 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
258 | This returns the "current wallclock time" as a fractional number of |
131 | called on c<$cv>, while servicing other watchers normally. |
259 | seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time> |
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260 | return, and the result is guaranteed to be compatible with those). |
132 | |
261 | |
133 | Not all event models support a blocking wait - some die in that case, so |
262 | It progresses independently of any event loop processing, i.e. each call |
134 | if you are using this from a module, never require a blocking wait, but |
263 | will check the system clock, which usually gets updated frequently. |
135 | let the caller decide wether the call will block or not (for example, |
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136 | by coupling condition variables with some kind of request results and |
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137 | supporting callbacks so the caller knows that getting the result will not |
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138 | block, while still suppporting blockign waits if the caller so desires). |
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139 | |
264 | |
140 | You can only wait once on a condition - additional calls will return |
265 | =item AnyEvent->now |
141 | immediately. |
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142 | |
266 | |
143 | =item $cv->broadcast |
267 | This also returns the "current wallclock time", but unlike C<time>, above, |
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268 | this value might change only once per event loop iteration, depending on |
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269 | the event loop (most return the same time as C<time>, above). This is the |
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270 | time that AnyEvent's timers get scheduled against. |
144 | |
271 | |
145 | Flag the condition as ready - a running C<< ->wait >> and all further |
272 | I<In almost all cases (in all cases if you don't care), this is the |
146 | calls to C<wait> will return after this method has been called. If nobody |
273 | function to call when you want to know the current time.> |
147 | is waiting the broadcast will be remembered.. |
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148 | |
274 | |
149 | Example: |
275 | This function is also often faster then C<< AnyEvent->time >>, and |
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276 | thus the preferred method if you want some timestamp (for example, |
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277 | L<AnyEvent::Handle> uses this to update it's activity timeouts). |
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278 | |
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279 | The rest of this section is only of relevance if you try to be very exact |
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280 | with your timing, you can skip it without bad conscience. |
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281 | |
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282 | For a practical example of when these times differ, consider L<Event::Lib> |
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283 | and L<EV> and the following set-up: |
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284 | |
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285 | The event loop is running and has just invoked one of your callback at |
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286 | time=500 (assume no other callbacks delay processing). In your callback, |
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287 | you wait a second by executing C<sleep 1> (blocking the process for a |
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288 | second) and then (at time=501) you create a relative timer that fires |
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289 | after three seconds. |
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290 | |
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291 | With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will |
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292 | both return C<501>, because that is the current time, and the timer will |
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293 | be scheduled to fire at time=504 (C<501> + C<3>). |
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294 | |
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295 | With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current |
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296 | time), but C<< AnyEvent->now >> returns C<500>, as that is the time the |
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297 | last event processing phase started. With L<EV>, your timer gets scheduled |
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298 | to run at time=503 (C<500> + C<3>). |
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299 | |
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300 | In one sense, L<Event::Lib> is more exact, as it uses the current time |
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301 | regardless of any delays introduced by event processing. However, most |
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302 | callbacks do not expect large delays in processing, so this causes a |
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303 | higher drift (and a lot more system calls to get the current time). |
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304 | |
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305 | In another sense, L<EV> is more exact, as your timer will be scheduled at |
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306 | the same time, regardless of how long event processing actually took. |
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307 | |
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308 | In either case, if you care (and in most cases, you don't), then you |
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309 | can get whatever behaviour you want with any event loop, by taking the |
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310 | difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into |
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311 | account. |
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312 | |
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313 | =back |
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314 | |
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315 | =head2 SIGNAL WATCHERS |
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316 | |
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317 | You can watch for signals using a signal watcher, C<signal> is the signal |
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318 | I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl |
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319 | callback to be invoked whenever a signal occurs. |
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320 | |
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321 | Although the callback might get passed parameters, their value and |
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322 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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323 | callbacks cannot use arguments passed to signal watcher callbacks. |
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324 | |
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325 | Multiple signal occurrences can be clumped together into one callback |
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326 | invocation, and callback invocation will be synchronous. Synchronous means |
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327 | that it might take a while until the signal gets handled by the process, |
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328 | but it is guaranteed not to interrupt any other callbacks. |
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329 | |
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330 | The main advantage of using these watchers is that you can share a signal |
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331 | between multiple watchers. |
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332 | |
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333 | This watcher might use C<%SIG>, so programs overwriting those signals |
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334 | directly will likely not work correctly. |
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335 | |
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336 | Example: exit on SIGINT |
|
|
337 | |
|
|
338 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
339 | |
|
|
340 | =head2 CHILD PROCESS WATCHERS |
|
|
341 | |
|
|
342 | You can also watch on a child process exit and catch its exit status. |
|
|
343 | |
|
|
344 | The child process is specified by the C<pid> argument (if set to C<0>, it |
|
|
345 | watches for any child process exit). The watcher will triggered only when |
|
|
346 | the child process has finished and an exit status is available, not on |
|
|
347 | any trace events (stopped/continued). |
|
|
348 | |
|
|
349 | The callback will be called with the pid and exit status (as returned by |
|
|
350 | waitpid), so unlike other watcher types, you I<can> rely on child watcher |
|
|
351 | callback arguments. |
|
|
352 | |
|
|
353 | This watcher type works by installing a signal handler for C<SIGCHLD>, |
|
|
354 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
|
|
355 | random child processes (waiting for specific child processes, e.g. inside |
|
|
356 | C<system>, is just fine). |
|
|
357 | |
|
|
358 | There is a slight catch to child watchers, however: you usually start them |
|
|
359 | I<after> the child process was created, and this means the process could |
|
|
360 | have exited already (and no SIGCHLD will be sent anymore). |
|
|
361 | |
|
|
362 | Not all event models handle this correctly (POE doesn't), but even for |
|
|
363 | event models that I<do> handle this correctly, they usually need to be |
|
|
364 | loaded before the process exits (i.e. before you fork in the first place). |
|
|
365 | |
|
|
366 | This means you cannot create a child watcher as the very first thing in an |
|
|
367 | AnyEvent program, you I<have> to create at least one watcher before you |
|
|
368 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
|
|
369 | |
|
|
370 | Example: fork a process and wait for it |
|
|
371 | |
|
|
372 | my $done = AnyEvent->condvar; |
|
|
373 | |
|
|
374 | my $pid = fork or exit 5; |
|
|
375 | |
|
|
376 | my $w = AnyEvent->child ( |
|
|
377 | pid => $pid, |
|
|
378 | cb => sub { |
|
|
379 | my ($pid, $status) = @_; |
|
|
380 | warn "pid $pid exited with status $status"; |
|
|
381 | $done->send; |
|
|
382 | }, |
|
|
383 | ); |
|
|
384 | |
|
|
385 | # do something else, then wait for process exit |
|
|
386 | $done->recv; |
|
|
387 | |
|
|
388 | =head2 CONDITION VARIABLES |
|
|
389 | |
|
|
390 | If you are familiar with some event loops you will know that all of them |
|
|
391 | require you to run some blocking "loop", "run" or similar function that |
|
|
392 | will actively watch for new events and call your callbacks. |
|
|
393 | |
|
|
394 | AnyEvent is different, it expects somebody else to run the event loop and |
|
|
395 | will only block when necessary (usually when told by the user). |
|
|
396 | |
|
|
397 | The instrument to do that is called a "condition variable", so called |
|
|
398 | because they represent a condition that must become true. |
|
|
399 | |
|
|
400 | Condition variables can be created by calling the C<< AnyEvent->condvar |
|
|
401 | >> method, usually without arguments. The only argument pair allowed is |
|
|
402 | |
|
|
403 | C<cb>, which specifies a callback to be called when the condition variable |
|
|
404 | becomes true, with the condition variable as the first argument (but not |
|
|
405 | the results). |
|
|
406 | |
|
|
407 | After creation, the condition variable is "false" until it becomes "true" |
|
|
408 | by calling the C<send> method (or calling the condition variable as if it |
|
|
409 | were a callback, read about the caveats in the description for the C<< |
|
|
410 | ->send >> method). |
|
|
411 | |
|
|
412 | Condition variables are similar to callbacks, except that you can |
|
|
413 | optionally wait for them. They can also be called merge points - points |
|
|
414 | in time where multiple outstanding events have been processed. And yet |
|
|
415 | another way to call them is transactions - each condition variable can be |
|
|
416 | used to represent a transaction, which finishes at some point and delivers |
|
|
417 | a result. |
|
|
418 | |
|
|
419 | Condition variables are very useful to signal that something has finished, |
|
|
420 | for example, if you write a module that does asynchronous http requests, |
|
|
421 | then a condition variable would be the ideal candidate to signal the |
|
|
422 | availability of results. The user can either act when the callback is |
|
|
423 | called or can synchronously C<< ->recv >> for the results. |
|
|
424 | |
|
|
425 | You can also use them to simulate traditional event loops - for example, |
|
|
426 | you can block your main program until an event occurs - for example, you |
|
|
427 | could C<< ->recv >> in your main program until the user clicks the Quit |
|
|
428 | button of your app, which would C<< ->send >> the "quit" event. |
|
|
429 | |
|
|
430 | Note that condition variables recurse into the event loop - if you have |
|
|
431 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
|
|
432 | lose. Therefore, condition variables are good to export to your caller, but |
|
|
433 | you should avoid making a blocking wait yourself, at least in callbacks, |
|
|
434 | as this asks for trouble. |
|
|
435 | |
|
|
436 | Condition variables are represented by hash refs in perl, and the keys |
|
|
437 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
|
|
438 | easy (it is often useful to build your own transaction class on top of |
|
|
439 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
|
|
440 | it's C<new> method in your own C<new> method. |
|
|
441 | |
|
|
442 | There are two "sides" to a condition variable - the "producer side" which |
|
|
443 | eventually calls C<< -> send >>, and the "consumer side", which waits |
|
|
444 | for the send to occur. |
|
|
445 | |
|
|
446 | Example: wait for a timer. |
150 | |
447 | |
151 | # wait till the result is ready |
448 | # wait till the result is ready |
152 | my $result_ready = AnyEvent->condvar; |
449 | my $result_ready = AnyEvent->condvar; |
153 | |
450 | |
154 | # do something such as adding a timer |
451 | # do something such as adding a timer |
155 | # or socket watcher the calls $result_ready->broadcast |
452 | # or socket watcher the calls $result_ready->send |
156 | # when the "result" is ready. |
453 | # when the "result" is ready. |
|
|
454 | # in this case, we simply use a timer: |
|
|
455 | my $w = AnyEvent->timer ( |
|
|
456 | after => 1, |
|
|
457 | cb => sub { $result_ready->send }, |
|
|
458 | ); |
157 | |
459 | |
|
|
460 | # this "blocks" (while handling events) till the callback |
|
|
461 | # calls send |
158 | $result_ready->wait; |
462 | $result_ready->recv; |
|
|
463 | |
|
|
464 | Example: wait for a timer, but take advantage of the fact that |
|
|
465 | condition variables are also code references. |
|
|
466 | |
|
|
467 | my $done = AnyEvent->condvar; |
|
|
468 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
|
|
469 | $done->recv; |
|
|
470 | |
|
|
471 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
472 | callbacks. This is how you make a synchronous call, for example from |
|
|
473 | the main program: |
|
|
474 | |
|
|
475 | use AnyEvent::CouchDB; |
|
|
476 | |
|
|
477 | ... |
|
|
478 | |
|
|
479 | my @info = $couchdb->info->recv; |
|
|
480 | |
|
|
481 | And this is how you would just ste a callback to be called whenever the |
|
|
482 | results are available: |
|
|
483 | |
|
|
484 | $couchdb->info->cb (sub { |
|
|
485 | my @info = $_[0]->recv; |
|
|
486 | }); |
|
|
487 | |
|
|
488 | =head3 METHODS FOR PRODUCERS |
|
|
489 | |
|
|
490 | These methods should only be used by the producing side, i.e. the |
|
|
491 | code/module that eventually sends the signal. Note that it is also |
|
|
492 | the producer side which creates the condvar in most cases, but it isn't |
|
|
493 | uncommon for the consumer to create it as well. |
|
|
494 | |
|
|
495 | =over 4 |
|
|
496 | |
|
|
497 | =item $cv->send (...) |
|
|
498 | |
|
|
499 | Flag the condition as ready - a running C<< ->recv >> and all further |
|
|
500 | calls to C<recv> will (eventually) return after this method has been |
|
|
501 | called. If nobody is waiting the send will be remembered. |
|
|
502 | |
|
|
503 | If a callback has been set on the condition variable, it is called |
|
|
504 | immediately from within send. |
|
|
505 | |
|
|
506 | Any arguments passed to the C<send> call will be returned by all |
|
|
507 | future C<< ->recv >> calls. |
|
|
508 | |
|
|
509 | Condition variables are overloaded so one can call them directly |
|
|
510 | (as a code reference). Calling them directly is the same as calling |
|
|
511 | C<send>. Note, however, that many C-based event loops do not handle |
|
|
512 | overloading, so as tempting as it may be, passing a condition variable |
|
|
513 | instead of a callback does not work. Both the pure perl and EV loops |
|
|
514 | support overloading, however, as well as all functions that use perl to |
|
|
515 | invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for |
|
|
516 | example). |
|
|
517 | |
|
|
518 | =item $cv->croak ($error) |
|
|
519 | |
|
|
520 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
|
|
521 | C<Carp::croak> with the given error message/object/scalar. |
|
|
522 | |
|
|
523 | This can be used to signal any errors to the condition variable |
|
|
524 | user/consumer. |
|
|
525 | |
|
|
526 | =item $cv->begin ([group callback]) |
|
|
527 | |
|
|
528 | =item $cv->end |
|
|
529 | |
|
|
530 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
531 | |
|
|
532 | These two methods can be used to combine many transactions/events into |
|
|
533 | one. For example, a function that pings many hosts in parallel might want |
|
|
534 | to use a condition variable for the whole process. |
|
|
535 | |
|
|
536 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
537 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
538 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
539 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
540 | callback was set, C<send> will be called without any arguments. |
|
|
541 | |
|
|
542 | Let's clarify this with the ping example: |
|
|
543 | |
|
|
544 | my $cv = AnyEvent->condvar; |
|
|
545 | |
|
|
546 | my %result; |
|
|
547 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
548 | |
|
|
549 | for my $host (@list_of_hosts) { |
|
|
550 | $cv->begin; |
|
|
551 | ping_host_then_call_callback $host, sub { |
|
|
552 | $result{$host} = ...; |
|
|
553 | $cv->end; |
|
|
554 | }; |
|
|
555 | } |
|
|
556 | |
|
|
557 | $cv->end; |
|
|
558 | |
|
|
559 | This code fragment supposedly pings a number of hosts and calls |
|
|
560 | C<send> after results for all then have have been gathered - in any |
|
|
561 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
562 | each ping request and calls C<end> when it has received some result for |
|
|
563 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
564 | results arrive is not relevant. |
|
|
565 | |
|
|
566 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
567 | loop, which serves two important purposes: first, it sets the callback |
|
|
568 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
569 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
570 | doesn't execute once). |
|
|
571 | |
|
|
572 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
573 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
574 | is called at least once, and then, for each subrequest you start, call |
|
|
575 | C<begin> and for each subrequest you finish, call C<end>. |
159 | |
576 | |
160 | =back |
577 | =back |
161 | |
578 | |
162 | =head2 SIGNAL WATCHERS |
579 | =head3 METHODS FOR CONSUMERS |
163 | |
580 | |
164 | You can listen for signals using a signal watcher, C<signal> is the signal |
581 | These methods should only be used by the consuming side, i.e. the |
165 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
582 | code awaits the condition. |
166 | together into one callback invocation, and callback invocation might or |
|
|
167 | might not be asynchronous. |
|
|
168 | |
583 | |
169 | These watchers might use C<%SIG>, so programs overwriting those signals |
584 | =over 4 |
170 | directly will likely not work correctly. |
|
|
171 | |
585 | |
172 | Example: exit on SIGINT |
586 | =item $cv->recv |
173 | |
587 | |
174 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
588 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
|
|
589 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
590 | normally. |
175 | |
591 | |
176 | =head2 CHILD PROCESS WATCHERS |
592 | You can only wait once on a condition - additional calls are valid but |
|
|
593 | will return immediately. |
177 | |
594 | |
178 | You can also listen for the status of a child process specified by the |
595 | If an error condition has been set by calling C<< ->croak >>, then this |
179 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
596 | function will call C<croak>. |
180 | trigger as often as status change for the child are received. This works |
|
|
181 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
|
|
182 | the pid and exit status (as returned by waitpid). |
|
|
183 | |
597 | |
184 | Example: wait for pid 1333 |
598 | In list context, all parameters passed to C<send> will be returned, |
|
|
599 | in scalar context only the first one will be returned. |
185 | |
600 | |
186 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
601 | Not all event models support a blocking wait - some die in that case |
|
|
602 | (programs might want to do that to stay interactive), so I<if you are |
|
|
603 | using this from a module, never require a blocking wait>, but let the |
|
|
604 | caller decide whether the call will block or not (for example, by coupling |
|
|
605 | condition variables with some kind of request results and supporting |
|
|
606 | callbacks so the caller knows that getting the result will not block, |
|
|
607 | while still supporting blocking waits if the caller so desires). |
187 | |
608 | |
188 | =head1 GLOBALS |
609 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
|
|
610 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
|
|
611 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
|
|
612 | can supply. |
|
|
613 | |
|
|
614 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
615 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
616 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
617 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
618 | coroutine (one that doesn't run the event loop). |
|
|
619 | |
|
|
620 | You can ensure that C<< -recv >> never blocks by setting a callback and |
|
|
621 | only calling C<< ->recv >> from within that callback (or at a later |
|
|
622 | time). This will work even when the event loop does not support blocking |
|
|
623 | waits otherwise. |
|
|
624 | |
|
|
625 | =item $bool = $cv->ready |
|
|
626 | |
|
|
627 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
628 | C<croak> have been called. |
|
|
629 | |
|
|
630 | =item $cb = $cv->cb ($cb->($cv)) |
|
|
631 | |
|
|
632 | This is a mutator function that returns the callback set and optionally |
|
|
633 | replaces it before doing so. |
|
|
634 | |
|
|
635 | The callback will be called when the condition becomes "true", i.e. when |
|
|
636 | C<send> or C<croak> are called, with the only argument being the condition |
|
|
637 | variable itself. Calling C<recv> inside the callback or at any later time |
|
|
638 | is guaranteed not to block. |
|
|
639 | |
|
|
640 | =back |
|
|
641 | |
|
|
642 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
189 | |
643 | |
190 | =over 4 |
644 | =over 4 |
191 | |
645 | |
192 | =item $AnyEvent::MODEL |
646 | =item $AnyEvent::MODEL |
193 | |
647 | |
… | |
… | |
197 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
651 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
198 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
652 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
199 | |
653 | |
200 | The known classes so far are: |
654 | The known classes so far are: |
201 | |
655 | |
202 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
|
|
203 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
656 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
204 | AnyEvent::Impl::Coro based on Coro::Event, second best choice. |
|
|
205 | AnyEvent::Impl::Event based on Event, also second best choice :) |
657 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
658 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
206 | AnyEvent::Impl::Glib based on Glib, second-best choice. |
659 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
207 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
660 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
208 | AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
661 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
662 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
663 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
664 | |
|
|
665 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
666 | watching file handles. However, you can use WxWidgets through the |
|
|
667 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
668 | second, which was considered to be too horrible to even consider for |
|
|
669 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
670 | it's adaptor. |
|
|
671 | |
|
|
672 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
673 | autodetecting them. |
209 | |
674 | |
210 | =item AnyEvent::detect |
675 | =item AnyEvent::detect |
211 | |
676 | |
212 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
677 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
213 | necessary. You should only call this function right before you would have |
678 | if necessary. You should only call this function right before you would |
214 | created an AnyEvent watcher anyway, that is, very late at runtime. |
679 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
680 | runtime. |
|
|
681 | |
|
|
682 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
683 | |
|
|
684 | Arranges for the code block to be executed as soon as the event model is |
|
|
685 | autodetected (or immediately if this has already happened). |
|
|
686 | |
|
|
687 | If called in scalar or list context, then it creates and returns an object |
|
|
688 | that automatically removes the callback again when it is destroyed. See |
|
|
689 | L<Coro::BDB> for a case where this is useful. |
|
|
690 | |
|
|
691 | =item @AnyEvent::post_detect |
|
|
692 | |
|
|
693 | If there are any code references in this array (you can C<push> to it |
|
|
694 | before or after loading AnyEvent), then they will called directly after |
|
|
695 | the event loop has been chosen. |
|
|
696 | |
|
|
697 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
698 | if it contains a true value then the event loop has already been detected, |
|
|
699 | and the array will be ignored. |
|
|
700 | |
|
|
701 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
215 | |
702 | |
216 | =back |
703 | =back |
217 | |
704 | |
218 | =head1 WHAT TO DO IN A MODULE |
705 | =head1 WHAT TO DO IN A MODULE |
219 | |
706 | |
220 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
707 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
221 | freely, but you should not load a specific event module or rely on it. |
708 | freely, but you should not load a specific event module or rely on it. |
222 | |
709 | |
223 | Be careful when you create watchers in the module body - Anyevent will |
710 | Be careful when you create watchers in the module body - AnyEvent will |
224 | decide which event module to use as soon as the first method is called, so |
711 | decide which event module to use as soon as the first method is called, so |
225 | by calling AnyEvent in your module body you force the user of your module |
712 | by calling AnyEvent in your module body you force the user of your module |
226 | to load the event module first. |
713 | to load the event module first. |
227 | |
714 | |
|
|
715 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
|
|
716 | the C<< ->send >> method has been called on it already. This is |
|
|
717 | because it will stall the whole program, and the whole point of using |
|
|
718 | events is to stay interactive. |
|
|
719 | |
|
|
720 | It is fine, however, to call C<< ->recv >> when the user of your module |
|
|
721 | requests it (i.e. if you create a http request object ad have a method |
|
|
722 | called C<results> that returns the results, it should call C<< ->recv >> |
|
|
723 | freely, as the user of your module knows what she is doing. always). |
|
|
724 | |
228 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
725 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
229 | |
726 | |
230 | There will always be a single main program - the only place that should |
727 | There will always be a single main program - the only place that should |
231 | dictate which event model to use. |
728 | dictate which event model to use. |
232 | |
729 | |
233 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
730 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
234 | do anything special and let AnyEvent decide which implementation to chose. |
731 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
732 | decide which implementation to chose if some module relies on it. |
235 | |
733 | |
236 | If the main program relies on a specific event model (for example, in Gtk2 |
734 | If the main program relies on a specific event model - for example, in |
237 | programs you have to rely on either Glib or Glib::Event), you should load |
735 | Gtk2 programs you have to rely on the Glib module - you should load the |
238 | it before loading AnyEvent or any module that uses it, generally, as early |
736 | event module before loading AnyEvent or any module that uses it: generally |
239 | as possible. The reason is that modules might create watchers when they |
737 | speaking, you should load it as early as possible. The reason is that |
240 | are loaded, and AnyEvent will decide on the event model to use as soon as |
738 | modules might create watchers when they are loaded, and AnyEvent will |
241 | it creates watchers, and it might chose the wrong one unless you load the |
739 | decide on the event model to use as soon as it creates watchers, and it |
242 | correct one yourself. |
740 | might chose the wrong one unless you load the correct one yourself. |
243 | |
741 | |
244 | You can chose to use a rather inefficient pure-perl implementation by |
742 | You can chose to use a pure-perl implementation by loading the |
245 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
743 | C<AnyEvent::Impl::Perl> module, which gives you similar behaviour |
246 | generally better. |
744 | everywhere, but letting AnyEvent chose the model is generally better. |
|
|
745 | |
|
|
746 | =head2 MAINLOOP EMULATION |
|
|
747 | |
|
|
748 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
749 | only want to use AnyEvent), you do not want to run a specific event loop. |
|
|
750 | |
|
|
751 | In that case, you can use a condition variable like this: |
|
|
752 | |
|
|
753 | AnyEvent->condvar->recv; |
|
|
754 | |
|
|
755 | This has the effect of entering the event loop and looping forever. |
|
|
756 | |
|
|
757 | Note that usually your program has some exit condition, in which case |
|
|
758 | it is better to use the "traditional" approach of storing a condition |
|
|
759 | variable somewhere, waiting for it, and sending it when the program should |
|
|
760 | exit cleanly. |
|
|
761 | |
|
|
762 | |
|
|
763 | =head1 OTHER MODULES |
|
|
764 | |
|
|
765 | The following is a non-exhaustive list of additional modules that use |
|
|
766 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
767 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
768 | available via CPAN. |
|
|
769 | |
|
|
770 | =over 4 |
|
|
771 | |
|
|
772 | =item L<AnyEvent::Util> |
|
|
773 | |
|
|
774 | Contains various utility functions that replace often-used but blocking |
|
|
775 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
776 | |
|
|
777 | =item L<AnyEvent::Socket> |
|
|
778 | |
|
|
779 | Provides various utility functions for (internet protocol) sockets, |
|
|
780 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
781 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
782 | |
|
|
783 | =item L<AnyEvent::Handle> |
|
|
784 | |
|
|
785 | Provide read and write buffers, manages watchers for reads and writes, |
|
|
786 | supports raw and formatted I/O, I/O queued and fully transparent and |
|
|
787 | non-blocking SSL/TLS. |
|
|
788 | |
|
|
789 | =item L<AnyEvent::DNS> |
|
|
790 | |
|
|
791 | Provides rich asynchronous DNS resolver capabilities. |
|
|
792 | |
|
|
793 | =item L<AnyEvent::HTTP> |
|
|
794 | |
|
|
795 | A simple-to-use HTTP library that is capable of making a lot of concurrent |
|
|
796 | HTTP requests. |
|
|
797 | |
|
|
798 | =item L<AnyEvent::HTTPD> |
|
|
799 | |
|
|
800 | Provides a simple web application server framework. |
|
|
801 | |
|
|
802 | =item L<AnyEvent::FastPing> |
|
|
803 | |
|
|
804 | The fastest ping in the west. |
|
|
805 | |
|
|
806 | =item L<AnyEvent::DBI> |
|
|
807 | |
|
|
808 | Executes L<DBI> requests asynchronously in a proxy process. |
|
|
809 | |
|
|
810 | =item L<AnyEvent::AIO> |
|
|
811 | |
|
|
812 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
813 | programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent |
|
|
814 | together. |
|
|
815 | |
|
|
816 | =item L<AnyEvent::BDB> |
|
|
817 | |
|
|
818 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses |
|
|
819 | L<BDB> and AnyEvent together. |
|
|
820 | |
|
|
821 | =item L<AnyEvent::GPSD> |
|
|
822 | |
|
|
823 | A non-blocking interface to gpsd, a daemon delivering GPS information. |
|
|
824 | |
|
|
825 | =item L<AnyEvent::IGS> |
|
|
826 | |
|
|
827 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
828 | L<App::IGS>). |
|
|
829 | |
|
|
830 | =item L<AnyEvent::IRC> |
|
|
831 | |
|
|
832 | AnyEvent based IRC client module family (replacing the older Net::IRC3). |
|
|
833 | |
|
|
834 | =item L<Net::XMPP2> |
|
|
835 | |
|
|
836 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
837 | |
|
|
838 | =item L<Net::FCP> |
|
|
839 | |
|
|
840 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
841 | of AnyEvent. |
|
|
842 | |
|
|
843 | =item L<Event::ExecFlow> |
|
|
844 | |
|
|
845 | High level API for event-based execution flow control. |
|
|
846 | |
|
|
847 | =item L<Coro> |
|
|
848 | |
|
|
849 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
850 | |
|
|
851 | =item L<IO::Lambda> |
|
|
852 | |
|
|
853 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
854 | |
|
|
855 | =back |
247 | |
856 | |
248 | =cut |
857 | =cut |
249 | |
858 | |
250 | package AnyEvent; |
859 | package AnyEvent; |
251 | |
860 | |
252 | no warnings; |
861 | no warnings; |
253 | use strict; |
862 | use strict qw(vars subs); |
254 | |
863 | |
255 | use Carp; |
864 | use Carp; |
256 | |
865 | |
257 | our $VERSION = '2.55'; |
866 | our $VERSION = 4.32; |
258 | our $MODEL; |
867 | our $MODEL; |
259 | |
868 | |
260 | our $AUTOLOAD; |
869 | our $AUTOLOAD; |
261 | our @ISA; |
870 | our @ISA; |
262 | |
871 | |
|
|
872 | our @REGISTRY; |
|
|
873 | |
|
|
874 | our $WIN32; |
|
|
875 | |
|
|
876 | BEGIN { |
|
|
877 | my $win32 = ! ! ($^O =~ /mswin32/i); |
|
|
878 | eval "sub WIN32(){ $win32 }"; |
|
|
879 | } |
|
|
880 | |
263 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
881 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
264 | |
882 | |
265 | our @REGISTRY; |
883 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
|
|
884 | |
|
|
885 | { |
|
|
886 | my $idx; |
|
|
887 | $PROTOCOL{$_} = ++$idx |
|
|
888 | for reverse split /\s*,\s*/, |
|
|
889 | $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
890 | } |
266 | |
891 | |
267 | my @models = ( |
892 | my @models = ( |
268 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
269 | [EV:: => AnyEvent::Impl::EV::], |
893 | [EV:: => AnyEvent::Impl::EV::], |
270 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
|
|
271 | [Event:: => AnyEvent::Impl::Event::], |
894 | [Event:: => AnyEvent::Impl::Event::], |
272 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
273 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
274 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
895 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
896 | # everything below here will not be autoprobed |
|
|
897 | # as the pureperl backend should work everywhere |
|
|
898 | # and is usually faster |
|
|
899 | [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles |
|
|
900 | [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers |
|
|
901 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
902 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
903 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
|
|
904 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
905 | [Prima:: => AnyEvent::Impl::POE::], |
275 | ); |
906 | ); |
276 | |
907 | |
277 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
908 | our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); |
|
|
909 | |
|
|
910 | our @post_detect; |
|
|
911 | |
|
|
912 | sub post_detect(&) { |
|
|
913 | my ($cb) = @_; |
|
|
914 | |
|
|
915 | if ($MODEL) { |
|
|
916 | $cb->(); |
|
|
917 | |
|
|
918 | 1 |
|
|
919 | } else { |
|
|
920 | push @post_detect, $cb; |
|
|
921 | |
|
|
922 | defined wantarray |
|
|
923 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
924 | : () |
|
|
925 | } |
|
|
926 | } |
|
|
927 | |
|
|
928 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
929 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
930 | } |
278 | |
931 | |
279 | sub detect() { |
932 | sub detect() { |
280 | unless ($MODEL) { |
933 | unless ($MODEL) { |
281 | no strict 'refs'; |
934 | no strict 'refs'; |
|
|
935 | local $SIG{__DIE__}; |
|
|
936 | |
|
|
937 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
938 | my $model = "AnyEvent::Impl::$1"; |
|
|
939 | if (eval "require $model") { |
|
|
940 | $MODEL = $model; |
|
|
941 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
942 | } else { |
|
|
943 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
944 | } |
|
|
945 | } |
282 | |
946 | |
283 | # check for already loaded models |
947 | # check for already loaded models |
|
|
948 | unless ($MODEL) { |
284 | for (@REGISTRY, @models) { |
949 | for (@REGISTRY, @models) { |
285 | my ($package, $model) = @$_; |
950 | my ($package, $model) = @$_; |
286 | if (${"$package\::VERSION"} > 0) { |
951 | if (${"$package\::VERSION"} > 0) { |
287 | if (eval "require $model") { |
952 | if (eval "require $model") { |
288 | $MODEL = $model; |
953 | $MODEL = $model; |
289 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
954 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
290 | last; |
955 | last; |
|
|
956 | } |
291 | } |
957 | } |
292 | } |
958 | } |
|
|
959 | |
|
|
960 | unless ($MODEL) { |
|
|
961 | # try to load a model |
|
|
962 | |
|
|
963 | for (@REGISTRY, @models) { |
|
|
964 | my ($package, $model) = @$_; |
|
|
965 | if (eval "require $package" |
|
|
966 | and ${"$package\::VERSION"} > 0 |
|
|
967 | and eval "require $model") { |
|
|
968 | $MODEL = $model; |
|
|
969 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
|
|
970 | last; |
|
|
971 | } |
|
|
972 | } |
|
|
973 | |
|
|
974 | $MODEL |
|
|
975 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
|
|
976 | } |
293 | } |
977 | } |
294 | |
978 | |
295 | unless ($MODEL) { |
979 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
296 | # try to load a model |
|
|
297 | |
|
|
298 | for (@REGISTRY, @models) { |
|
|
299 | my ($package, $model) = @$_; |
|
|
300 | if (eval "require $package" |
|
|
301 | and ${"$package\::VERSION"} > 0 |
|
|
302 | and eval "require $model") { |
|
|
303 | $MODEL = $model; |
|
|
304 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
|
|
305 | last; |
|
|
306 | } |
|
|
307 | } |
|
|
308 | |
|
|
309 | $MODEL |
|
|
310 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk."; |
|
|
311 | } |
|
|
312 | |
980 | |
313 | unshift @ISA, $MODEL; |
981 | unshift @ISA, $MODEL; |
314 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
982 | |
|
|
983 | require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT}; |
|
|
984 | |
|
|
985 | (shift @post_detect)->() while @post_detect; |
315 | } |
986 | } |
316 | |
987 | |
317 | $MODEL |
988 | $MODEL |
318 | } |
989 | } |
319 | |
990 | |
… | |
… | |
327 | |
998 | |
328 | my $class = shift; |
999 | my $class = shift; |
329 | $class->$func (@_); |
1000 | $class->$func (@_); |
330 | } |
1001 | } |
331 | |
1002 | |
|
|
1003 | # utility function to dup a filehandle. this is used by many backends |
|
|
1004 | # to support binding more than one watcher per filehandle (they usually |
|
|
1005 | # allow only one watcher per fd, so we dup it to get a different one). |
|
|
1006 | sub _dupfh($$$$) { |
|
|
1007 | my ($poll, $fh, $r, $w) = @_; |
|
|
1008 | |
|
|
1009 | require Fcntl; |
|
|
1010 | |
|
|
1011 | # cygwin requires the fh mode to be matching, unix doesn't |
|
|
1012 | my ($rw, $mode) = $poll eq "r" ? ($r, "<") |
|
|
1013 | : $poll eq "w" ? ($w, ">") |
|
|
1014 | : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'"; |
|
|
1015 | |
|
|
1016 | open my $fh2, "$mode&" . fileno $fh |
|
|
1017 | or die "cannot dup() filehandle: $!"; |
|
|
1018 | |
|
|
1019 | # we assume CLOEXEC is already set by perl in all important cases |
|
|
1020 | |
|
|
1021 | ($fh2, $rw) |
|
|
1022 | } |
|
|
1023 | |
332 | package AnyEvent::Base; |
1024 | package AnyEvent::Base; |
333 | |
1025 | |
|
|
1026 | # default implementation for now and time |
|
|
1027 | |
|
|
1028 | BEGIN { |
|
|
1029 | if (eval "use Time::HiRes (); time (); 1") { |
|
|
1030 | *_time = \&Time::HiRes::time; |
|
|
1031 | # if (eval "use POSIX (); (POSIX::times())... |
|
|
1032 | } else { |
|
|
1033 | *_time = sub { time }; # epic fail |
|
|
1034 | } |
|
|
1035 | } |
|
|
1036 | |
|
|
1037 | sub time { _time } |
|
|
1038 | sub now { _time } |
|
|
1039 | |
334 | # default implementation for ->condvar, ->wait, ->broadcast |
1040 | # default implementation for ->condvar |
335 | |
1041 | |
336 | sub condvar { |
1042 | sub condvar { |
337 | bless \my $flag, "AnyEvent::Base::CondVar" |
1043 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
338 | } |
|
|
339 | |
|
|
340 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
341 | ${$_[0]}++; |
|
|
342 | } |
|
|
343 | |
|
|
344 | sub AnyEvent::Base::CondVar::wait { |
|
|
345 | AnyEvent->one_event while !${$_[0]}; |
|
|
346 | } |
1044 | } |
347 | |
1045 | |
348 | # default implementation for ->signal |
1046 | # default implementation for ->signal |
349 | |
1047 | |
350 | our %SIG_CB; |
1048 | our %SIG_CB; |
… | |
… | |
366 | sub AnyEvent::Base::Signal::DESTROY { |
1064 | sub AnyEvent::Base::Signal::DESTROY { |
367 | my ($signal, $cb) = @{$_[0]}; |
1065 | my ($signal, $cb) = @{$_[0]}; |
368 | |
1066 | |
369 | delete $SIG_CB{$signal}{$cb}; |
1067 | delete $SIG_CB{$signal}{$cb}; |
370 | |
1068 | |
371 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
1069 | delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; |
372 | } |
1070 | } |
373 | |
1071 | |
374 | # default implementation for ->child |
1072 | # default implementation for ->child |
375 | |
1073 | |
376 | our %PID_CB; |
1074 | our %PID_CB; |
377 | our $CHLD_W; |
1075 | our $CHLD_W; |
|
|
1076 | our $CHLD_DELAY_W; |
378 | our $PID_IDLE; |
1077 | our $PID_IDLE; |
379 | our $WNOHANG; |
1078 | our $WNOHANG; |
380 | |
1079 | |
381 | sub _child_wait { |
1080 | sub _child_wait { |
382 | while (0 <= (my $pid = waitpid -1, $WNOHANG)) { |
1081 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
383 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
1082 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
384 | (values %{ $PID_CB{0} || {} }); |
1083 | (values %{ $PID_CB{0} || {} }); |
385 | } |
1084 | } |
386 | |
1085 | |
387 | undef $PID_IDLE; |
1086 | undef $PID_IDLE; |
388 | } |
1087 | } |
389 | |
1088 | |
|
|
1089 | sub _sigchld { |
|
|
1090 | # make sure we deliver these changes "synchronous" with the event loop. |
|
|
1091 | $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
|
|
1092 | undef $CHLD_DELAY_W; |
|
|
1093 | &_child_wait; |
|
|
1094 | }); |
|
|
1095 | } |
|
|
1096 | |
390 | sub child { |
1097 | sub child { |
391 | my (undef, %arg) = @_; |
1098 | my (undef, %arg) = @_; |
392 | |
1099 | |
393 | defined (my $pid = $arg{pid} + 0) |
1100 | defined (my $pid = $arg{pid} + 0) |
394 | or Carp::croak "required option 'pid' is missing"; |
1101 | or Carp::croak "required option 'pid' is missing"; |
395 | |
1102 | |
396 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
1103 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
397 | |
1104 | |
398 | unless ($WNOHANG) { |
1105 | unless ($WNOHANG) { |
399 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
1106 | $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; |
400 | } |
1107 | } |
401 | |
1108 | |
402 | unless ($CHLD_W) { |
1109 | unless ($CHLD_W) { |
403 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait); |
1110 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
404 | # child could be a zombie already |
1111 | # child could be a zombie already, so make at least one round |
405 | $PID_IDLE ||= AnyEvent->timer (after => 0, cb => \&_child_wait); |
1112 | &_sigchld; |
406 | } |
1113 | } |
407 | |
1114 | |
408 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
1115 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
409 | } |
1116 | } |
410 | |
1117 | |
… | |
… | |
415 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
1122 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
416 | |
1123 | |
417 | undef $CHLD_W unless keys %PID_CB; |
1124 | undef $CHLD_W unless keys %PID_CB; |
418 | } |
1125 | } |
419 | |
1126 | |
|
|
1127 | package AnyEvent::CondVar; |
|
|
1128 | |
|
|
1129 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
1130 | |
|
|
1131 | package AnyEvent::CondVar::Base; |
|
|
1132 | |
|
|
1133 | use overload |
|
|
1134 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
1135 | fallback => 1; |
|
|
1136 | |
|
|
1137 | sub _send { |
|
|
1138 | # nop |
|
|
1139 | } |
|
|
1140 | |
|
|
1141 | sub send { |
|
|
1142 | my $cv = shift; |
|
|
1143 | $cv->{_ae_sent} = [@_]; |
|
|
1144 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
1145 | $cv->_send; |
|
|
1146 | } |
|
|
1147 | |
|
|
1148 | sub croak { |
|
|
1149 | $_[0]{_ae_croak} = $_[1]; |
|
|
1150 | $_[0]->send; |
|
|
1151 | } |
|
|
1152 | |
|
|
1153 | sub ready { |
|
|
1154 | $_[0]{_ae_sent} |
|
|
1155 | } |
|
|
1156 | |
|
|
1157 | sub _wait { |
|
|
1158 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
1159 | } |
|
|
1160 | |
|
|
1161 | sub recv { |
|
|
1162 | $_[0]->_wait; |
|
|
1163 | |
|
|
1164 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
1165 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
1166 | } |
|
|
1167 | |
|
|
1168 | sub cb { |
|
|
1169 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
1170 | $_[0]{_ae_cb} |
|
|
1171 | } |
|
|
1172 | |
|
|
1173 | sub begin { |
|
|
1174 | ++$_[0]{_ae_counter}; |
|
|
1175 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
1176 | } |
|
|
1177 | |
|
|
1178 | sub end { |
|
|
1179 | return if --$_[0]{_ae_counter}; |
|
|
1180 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
1181 | } |
|
|
1182 | |
|
|
1183 | # undocumented/compatibility with pre-3.4 |
|
|
1184 | *broadcast = \&send; |
|
|
1185 | *wait = \&_wait; |
|
|
1186 | |
|
|
1187 | =head1 ERROR AND EXCEPTION HANDLING |
|
|
1188 | |
|
|
1189 | In general, AnyEvent does not do any error handling - it relies on the |
|
|
1190 | caller to do that if required. The L<AnyEvent::Strict> module (see also |
|
|
1191 | the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict |
|
|
1192 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
1193 | development. |
|
|
1194 | |
|
|
1195 | As for exception handling (i.e. runtime errors and exceptions thrown while |
|
|
1196 | executing a callback), this is not only highly event-loop specific, but |
|
|
1197 | also not in any way wrapped by this module, as this is the job of the main |
|
|
1198 | program. |
|
|
1199 | |
|
|
1200 | The pure perl event loop simply re-throws the exception (usually |
|
|
1201 | within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<< |
|
|
1202 | $Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and |
|
|
1203 | so on. |
|
|
1204 | |
|
|
1205 | =head1 ENVIRONMENT VARIABLES |
|
|
1206 | |
|
|
1207 | The following environment variables are used by this module or its |
|
|
1208 | submodules: |
|
|
1209 | |
|
|
1210 | =over 4 |
|
|
1211 | |
|
|
1212 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1213 | |
|
|
1214 | By default, AnyEvent will be completely silent except in fatal |
|
|
1215 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1216 | talkative. |
|
|
1217 | |
|
|
1218 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1219 | conditions, such as not being able to load the event model specified by |
|
|
1220 | C<PERL_ANYEVENT_MODEL>. |
|
|
1221 | |
|
|
1222 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1223 | model it chooses. |
|
|
1224 | |
|
|
1225 | =item C<PERL_ANYEVENT_STRICT> |
|
|
1226 | |
|
|
1227 | AnyEvent does not do much argument checking by default, as thorough |
|
|
1228 | argument checking is very costly. Setting this variable to a true value |
|
|
1229 | will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly |
|
|
1230 | check the arguments passed to most method calls. If it finds any problems |
|
|
1231 | it will croak. |
|
|
1232 | |
|
|
1233 | In other words, enables "strict" mode. |
|
|
1234 | |
|
|
1235 | Unlike C<use strict>, it is definitely recommended ot keep it off in |
|
|
1236 | production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while |
|
|
1237 | developing programs can be very useful, however. |
|
|
1238 | |
|
|
1239 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1240 | |
|
|
1241 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1242 | auto detection and -probing kicks in. It must be a string consisting |
|
|
1243 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1244 | and the resulting module name is loaded and if the load was successful, |
|
|
1245 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1246 | auto detection and -probing. |
|
|
1247 | |
|
|
1248 | This functionality might change in future versions. |
|
|
1249 | |
|
|
1250 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1251 | could start your program like this: |
|
|
1252 | |
|
|
1253 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1254 | |
|
|
1255 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1256 | |
|
|
1257 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1258 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1259 | of auto probing). |
|
|
1260 | |
|
|
1261 | Must be set to a comma-separated list of protocols or address families, |
|
|
1262 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1263 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1264 | list. |
|
|
1265 | |
|
|
1266 | This variable can effectively be used for denial-of-service attacks |
|
|
1267 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1268 | small, as the program has to handle connection errors already- |
|
|
1269 | |
|
|
1270 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1271 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1272 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1273 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1274 | IPv6, but prefer IPv6 over IPv4. |
|
|
1275 | |
|
|
1276 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1277 | |
|
|
1278 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1279 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1280 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1281 | default. |
|
|
1282 | |
|
|
1283 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1284 | EDNS0 in its DNS requests. |
|
|
1285 | |
|
|
1286 | =item C<PERL_ANYEVENT_MAX_FORKS> |
|
|
1287 | |
|
|
1288 | The maximum number of child processes that C<AnyEvent::Util::fork_call> |
|
|
1289 | will create in parallel. |
|
|
1290 | |
|
|
1291 | =back |
|
|
1292 | |
420 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1293 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1294 | |
|
|
1295 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
1296 | a module. This section is only of use to event loop authors who want to |
|
|
1297 | provide AnyEvent compatibility. |
421 | |
1298 | |
422 | If you need to support another event library which isn't directly |
1299 | If you need to support another event library which isn't directly |
423 | supported by AnyEvent, you can supply your own interface to it by |
1300 | supported by AnyEvent, you can supply your own interface to it by |
424 | pushing, before the first watcher gets created, the package name of |
1301 | pushing, before the first watcher gets created, the package name of |
425 | the event module and the package name of the interface to use onto |
1302 | the event module and the package name of the interface to use onto |
426 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
1303 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
427 | AnyEvent. |
1304 | AnyEvent, so it is reasonably cheap. |
428 | |
1305 | |
429 | Example: |
1306 | Example: |
430 | |
1307 | |
431 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
1308 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
432 | |
1309 | |
433 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
1310 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
434 | package/class when it finds the C<urxvt> package/module is loaded. When |
1311 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
1312 | |
435 | AnyEvent is loaded and asked to find a suitable event model, it will |
1313 | When AnyEvent is loaded and asked to find a suitable event model, it |
436 | first check for the presence of urxvt. |
1314 | will first check for the presence of urxvt by trying to C<use> the |
|
|
1315 | C<urxvt::anyevent> module. |
437 | |
1316 | |
438 | The class should provide implementations for all watcher types (see |
1317 | The class should provide implementations for all watcher types. See |
439 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
1318 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
440 | (Source code) and so on for actual examples, use C<perldoc -m |
1319 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
441 | AnyEvent::Impl::Glib> to see the sources). |
1320 | see the sources. |
442 | |
1321 | |
|
|
1322 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
1323 | provide suitable (hopefully) replacements. |
|
|
1324 | |
443 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
1325 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
444 | uses the above line as-is. An interface isn't included in AnyEvent |
1326 | terminal emulator uses the above line as-is. An interface isn't included |
445 | because it doesn't make sense outside the embedded interpreter inside |
1327 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
446 | I<rxvt-unicode>, and it is updated and maintained as part of the |
1328 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
447 | I<rxvt-unicode> distribution. |
1329 | I<rxvt-unicode> distribution. |
448 | |
1330 | |
449 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
1331 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
450 | condition variables: code blocking while waiting for a condition will |
1332 | condition variables: code blocking while waiting for a condition will |
451 | C<die>. This still works with most modules/usages, and blocking calls must |
1333 | C<die>. This still works with most modules/usages, and blocking calls must |
452 | not be in an interactive application, so it makes sense. |
1334 | not be done in an interactive application, so it makes sense. |
453 | |
1335 | |
454 | =head1 ENVIRONMENT VARIABLES |
|
|
455 | |
|
|
456 | The following environment variables are used by this module: |
|
|
457 | |
|
|
458 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
|
|
459 | model gets used. |
|
|
460 | |
|
|
461 | =head1 EXAMPLE |
1336 | =head1 EXAMPLE PROGRAM |
462 | |
1337 | |
463 | The following program uses an io watcher to read data from stdin, a timer |
1338 | The following program uses an I/O watcher to read data from STDIN, a timer |
464 | to display a message once per second, and a condvar to exit the program |
1339 | to display a message once per second, and a condition variable to quit the |
465 | when the user enters quit: |
1340 | program when the user enters quit: |
466 | |
1341 | |
467 | use AnyEvent; |
1342 | use AnyEvent; |
468 | |
1343 | |
469 | my $cv = AnyEvent->condvar; |
1344 | my $cv = AnyEvent->condvar; |
470 | |
1345 | |
471 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
1346 | my $io_watcher = AnyEvent->io ( |
|
|
1347 | fh => \*STDIN, |
|
|
1348 | poll => 'r', |
|
|
1349 | cb => sub { |
472 | warn "io event <$_[0]>\n"; # will always output <r> |
1350 | warn "io event <$_[0]>\n"; # will always output <r> |
473 | chomp (my $input = <STDIN>); # read a line |
1351 | chomp (my $input = <STDIN>); # read a line |
474 | warn "read: $input\n"; # output what has been read |
1352 | warn "read: $input\n"; # output what has been read |
475 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1353 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
|
|
1354 | }, |
476 | }); |
1355 | ); |
477 | |
1356 | |
478 | my $time_watcher; # can only be used once |
1357 | my $time_watcher; # can only be used once |
479 | |
1358 | |
480 | sub new_timer { |
1359 | sub new_timer { |
481 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1360 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
484 | }); |
1363 | }); |
485 | } |
1364 | } |
486 | |
1365 | |
487 | new_timer; # create first timer |
1366 | new_timer; # create first timer |
488 | |
1367 | |
489 | $cv->wait; # wait until user enters /^q/i |
1368 | $cv->recv; # wait until user enters /^q/i |
490 | |
1369 | |
491 | =head1 REAL-WORLD EXAMPLE |
1370 | =head1 REAL-WORLD EXAMPLE |
492 | |
1371 | |
493 | Consider the L<Net::FCP> module. It features (among others) the following |
1372 | Consider the L<Net::FCP> module. It features (among others) the following |
494 | API calls, which are to freenet what HTTP GET requests are to http: |
1373 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
544 | syswrite $txn->{fh}, $txn->{request} |
1423 | syswrite $txn->{fh}, $txn->{request} |
545 | or die "connection or write error"; |
1424 | or die "connection or write error"; |
546 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1425 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
547 | |
1426 | |
548 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1427 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
549 | result and signals any possible waiters that the request ahs finished: |
1428 | result and signals any possible waiters that the request has finished: |
550 | |
1429 | |
551 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1430 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
552 | |
1431 | |
553 | if (end-of-file or data complete) { |
1432 | if (end-of-file or data complete) { |
554 | $txn->{result} = $txn->{buf}; |
1433 | $txn->{result} = $txn->{buf}; |
555 | $txn->{finished}->broadcast; |
1434 | $txn->{finished}->send; |
556 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1435 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
557 | } |
1436 | } |
558 | |
1437 | |
559 | The C<result> method, finally, just waits for the finished signal (if the |
1438 | The C<result> method, finally, just waits for the finished signal (if the |
560 | request was already finished, it doesn't wait, of course, and returns the |
1439 | request was already finished, it doesn't wait, of course, and returns the |
561 | data: |
1440 | data: |
562 | |
1441 | |
563 | $txn->{finished}->wait; |
1442 | $txn->{finished}->recv; |
564 | return $txn->{result}; |
1443 | return $txn->{result}; |
565 | |
1444 | |
566 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1445 | The actual code goes further and collects all errors (C<die>s, exceptions) |
567 | that occured during request processing. The C<result> method detects |
1446 | that occurred during request processing. The C<result> method detects |
568 | wether an exception as thrown (it is stored inside the $txn object) |
1447 | whether an exception as thrown (it is stored inside the $txn object) |
569 | and just throws the exception, which means connection errors and other |
1448 | and just throws the exception, which means connection errors and other |
570 | problems get reported tot he code that tries to use the result, not in a |
1449 | problems get reported tot he code that tries to use the result, not in a |
571 | random callback. |
1450 | random callback. |
572 | |
1451 | |
573 | All of this enables the following usage styles: |
1452 | All of this enables the following usage styles: |
574 | |
1453 | |
575 | 1. Blocking: |
1454 | 1. Blocking: |
576 | |
1455 | |
577 | my $data = $fcp->client_get ($url); |
1456 | my $data = $fcp->client_get ($url); |
578 | |
1457 | |
579 | 2. Blocking, but parallelizing: |
1458 | 2. Blocking, but running in parallel: |
580 | |
1459 | |
581 | my @datas = map $_->result, |
1460 | my @datas = map $_->result, |
582 | map $fcp->txn_client_get ($_), |
1461 | map $fcp->txn_client_get ($_), |
583 | @urls; |
1462 | @urls; |
584 | |
1463 | |
585 | Both blocking examples work without the module user having to know |
1464 | Both blocking examples work without the module user having to know |
586 | anything about events. |
1465 | anything about events. |
587 | |
1466 | |
588 | 3a. Event-based in a main program, using any support Event module: |
1467 | 3a. Event-based in a main program, using any supported event module: |
589 | |
1468 | |
590 | use Event; |
1469 | use EV; |
591 | |
1470 | |
592 | $fcp->txn_client_get ($url)->cb (sub { |
1471 | $fcp->txn_client_get ($url)->cb (sub { |
593 | my $txn = shift; |
1472 | my $txn = shift; |
594 | my $data = $txn->result; |
1473 | my $data = $txn->result; |
595 | ... |
1474 | ... |
596 | }); |
1475 | }); |
597 | |
1476 | |
598 | Event::loop; |
1477 | EV::loop; |
599 | |
1478 | |
600 | 3b. The module user could use AnyEvent, too: |
1479 | 3b. The module user could use AnyEvent, too: |
601 | |
1480 | |
602 | use AnyEvent; |
1481 | use AnyEvent; |
603 | |
1482 | |
604 | my $quit = AnyEvent->condvar; |
1483 | my $quit = AnyEvent->condvar; |
605 | |
1484 | |
606 | $fcp->txn_client_get ($url)->cb (sub { |
1485 | $fcp->txn_client_get ($url)->cb (sub { |
607 | ... |
1486 | ... |
608 | $quit->broadcast; |
1487 | $quit->send; |
609 | }); |
1488 | }); |
610 | |
1489 | |
611 | $quit->wait; |
1490 | $quit->recv; |
|
|
1491 | |
|
|
1492 | |
|
|
1493 | =head1 BENCHMARKS |
|
|
1494 | |
|
|
1495 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1496 | over the event loops themselves and to give you an impression of the speed |
|
|
1497 | of various event loops I prepared some benchmarks. |
|
|
1498 | |
|
|
1499 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1500 | |
|
|
1501 | Here is a benchmark of various supported event models used natively and |
|
|
1502 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1503 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1504 | which it is), lets them fire exactly once and destroys them again. |
|
|
1505 | |
|
|
1506 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1507 | distribution. |
|
|
1508 | |
|
|
1509 | =head3 Explanation of the columns |
|
|
1510 | |
|
|
1511 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1512 | different event models feature vastly different performances, each event |
|
|
1513 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1514 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1515 | would probably take thousands of years if asked to process the same number |
|
|
1516 | of watchers as EV in this benchmark. |
|
|
1517 | |
|
|
1518 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1519 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1520 | and Perl-based overheads. |
|
|
1521 | |
|
|
1522 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1523 | takes to create a single watcher. The callback is a closure shared between |
|
|
1524 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1525 | and memory usage is not included in the figures. |
|
|
1526 | |
|
|
1527 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1528 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1529 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1530 | signal the end of this phase. |
|
|
1531 | |
|
|
1532 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1533 | watcher. |
|
|
1534 | |
|
|
1535 | =head3 Results |
|
|
1536 | |
|
|
1537 | name watchers bytes create invoke destroy comment |
|
|
1538 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
|
|
1539 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
|
|
1540 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
|
|
1541 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
|
|
1542 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
|
|
1543 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1544 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
|
|
1545 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
|
|
1546 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
|
|
1547 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
|
|
1548 | |
|
|
1549 | =head3 Discussion |
|
|
1550 | |
|
|
1551 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1552 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1553 | can never compete with an event loop that uses epoll when the number of |
|
|
1554 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1555 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1556 | boost. |
|
|
1557 | |
|
|
1558 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1559 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1560 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1561 | higher number of watchers at a disadvantage. |
|
|
1562 | |
|
|
1563 | To put the range of results into perspective, consider that on the |
|
|
1564 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1565 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1566 | cycles with POE. |
|
|
1567 | |
|
|
1568 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1569 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1570 | far less memory than any other event loop and is still faster than Event |
|
|
1571 | natively. |
|
|
1572 | |
|
|
1573 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1574 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1575 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1576 | adds very little overhead in itself. Like any select-based backend its |
|
|
1577 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1578 | them active), of course, but this was not subject of this benchmark. |
|
|
1579 | |
|
|
1580 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1581 | cost, but overall scores in on the third place. |
|
|
1582 | |
|
|
1583 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1584 | faster callback invocation and overall ends up in the same class as |
|
|
1585 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1586 | watchers increases the processing time by more than a factor of four, |
|
|
1587 | making it completely unusable when using larger numbers of watchers |
|
|
1588 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1589 | inefficiencies of C<poll> do not account for this). |
|
|
1590 | |
|
|
1591 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1592 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1593 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1594 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1595 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1596 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1597 | above). |
|
|
1598 | |
|
|
1599 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1600 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1601 | be tested because it wasn't working) shows abysmal performance and |
|
|
1602 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1603 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1604 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1605 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1606 | implementation. |
|
|
1607 | |
|
|
1608 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1609 | for the performance issues, though, as session creation overhead is |
|
|
1610 | small compared to execution of the state machine, which is coded pretty |
|
|
1611 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1612 | using multiple sessions is not a good approach, especially regarding |
|
|
1613 | memory usage, even the author of POE could not come up with a faster |
|
|
1614 | design). |
|
|
1615 | |
|
|
1616 | =head3 Summary |
|
|
1617 | |
|
|
1618 | =over 4 |
|
|
1619 | |
|
|
1620 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1621 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1622 | performance with or without AnyEvent. |
|
|
1623 | |
|
|
1624 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1625 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1626 | adds AnyEvent significant overhead. |
|
|
1627 | |
|
|
1628 | =item * You should avoid POE like the plague if you want performance or |
|
|
1629 | reasonable memory usage. |
|
|
1630 | |
|
|
1631 | =back |
|
|
1632 | |
|
|
1633 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1634 | |
|
|
1635 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1636 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1637 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1638 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1639 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1640 | |
|
|
1641 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1642 | are active at any one point (so there is a constant number of active |
|
|
1643 | fds for each loop iteration, but which fds these are is random). The |
|
|
1644 | timeout is reset each time something is read because that reflects how |
|
|
1645 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1646 | |
|
|
1647 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1648 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1649 | connections, most of which are idle at any one point in time. |
|
|
1650 | |
|
|
1651 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1652 | distribution. |
|
|
1653 | |
|
|
1654 | =head3 Explanation of the columns |
|
|
1655 | |
|
|
1656 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1657 | each server has a read and write socket end). |
|
|
1658 | |
|
|
1659 | I<create> is the time it takes to create a socket pair (which is |
|
|
1660 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1661 | |
|
|
1662 | I<request>, the most important value, is the time it takes to handle a |
|
|
1663 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1664 | it to another server. This includes deleting the old timeout and creating |
|
|
1665 | a new one that moves the timeout into the future. |
|
|
1666 | |
|
|
1667 | =head3 Results |
|
|
1668 | |
|
|
1669 | name sockets create request |
|
|
1670 | EV 20000 69.01 11.16 |
|
|
1671 | Perl 20000 73.32 35.87 |
|
|
1672 | Event 20000 212.62 257.32 |
|
|
1673 | Glib 20000 651.16 1896.30 |
|
|
1674 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1675 | |
|
|
1676 | =head3 Discussion |
|
|
1677 | |
|
|
1678 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1679 | particular event loop. |
|
|
1680 | |
|
|
1681 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1682 | is relatively high, though. |
|
|
1683 | |
|
|
1684 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1685 | loops Event and Glib. |
|
|
1686 | |
|
|
1687 | Event suffers from high setup time as well (look at its code and you will |
|
|
1688 | understand why). Callback invocation also has a high overhead compared to |
|
|
1689 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1690 | uses select or poll in basically all documented configurations. |
|
|
1691 | |
|
|
1692 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1693 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1694 | |
|
|
1695 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1696 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1697 | it uses a C-based event loop in this case. |
|
|
1698 | |
|
|
1699 | =head3 Summary |
|
|
1700 | |
|
|
1701 | =over 4 |
|
|
1702 | |
|
|
1703 | =item * The pure perl implementation performs extremely well. |
|
|
1704 | |
|
|
1705 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1706 | |
|
|
1707 | =back |
|
|
1708 | |
|
|
1709 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1710 | |
|
|
1711 | While event loops should scale (and select-based ones do not...) even to |
|
|
1712 | large servers, most programs we (or I :) actually write have only a few |
|
|
1713 | I/O watchers. |
|
|
1714 | |
|
|
1715 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1716 | case, but it uses only eight "servers", of which three are active at any |
|
|
1717 | one time. This should reflect performance for a small server relatively |
|
|
1718 | well. |
|
|
1719 | |
|
|
1720 | The columns are identical to the previous table. |
|
|
1721 | |
|
|
1722 | =head3 Results |
|
|
1723 | |
|
|
1724 | name sockets create request |
|
|
1725 | EV 16 20.00 6.54 |
|
|
1726 | Perl 16 25.75 12.62 |
|
|
1727 | Event 16 81.27 35.86 |
|
|
1728 | Glib 16 32.63 15.48 |
|
|
1729 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1730 | |
|
|
1731 | =head3 Discussion |
|
|
1732 | |
|
|
1733 | The benchmark tries to test the performance of a typical small |
|
|
1734 | server. While knowing how various event loops perform is interesting, keep |
|
|
1735 | in mind that their overhead in this case is usually not as important, due |
|
|
1736 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1737 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1738 | them). |
|
|
1739 | |
|
|
1740 | EV is again fastest. |
|
|
1741 | |
|
|
1742 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1743 | loops Event and Glib, although the difference is too small to really |
|
|
1744 | matter. |
|
|
1745 | |
|
|
1746 | POE also performs much better in this case, but is is still far behind the |
|
|
1747 | others. |
|
|
1748 | |
|
|
1749 | =head3 Summary |
|
|
1750 | |
|
|
1751 | =over 4 |
|
|
1752 | |
|
|
1753 | =item * C-based event loops perform very well with small number of |
|
|
1754 | watchers, as the management overhead dominates. |
|
|
1755 | |
|
|
1756 | =back |
|
|
1757 | |
|
|
1758 | |
|
|
1759 | =head1 SIGNALS |
|
|
1760 | |
|
|
1761 | AnyEvent currently installs handlers for these signals: |
|
|
1762 | |
|
|
1763 | =over 4 |
|
|
1764 | |
|
|
1765 | =item SIGCHLD |
|
|
1766 | |
|
|
1767 | A handler for C<SIGCHLD> is installed by AnyEvent's child watcher |
|
|
1768 | emulation for event loops that do not support them natively. Also, some |
|
|
1769 | event loops install a similar handler. |
|
|
1770 | |
|
|
1771 | =item SIGPIPE |
|
|
1772 | |
|
|
1773 | A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> |
|
|
1774 | when AnyEvent gets loaded. |
|
|
1775 | |
|
|
1776 | The rationale for this is that AnyEvent users usually do not really depend |
|
|
1777 | on SIGPIPE delivery (which is purely an optimisation for shell use, or |
|
|
1778 | badly-written programs), but C<SIGPIPE> can cause spurious and rare |
|
|
1779 | program exits as a lot of people do not expect C<SIGPIPE> when writing to |
|
|
1780 | some random socket. |
|
|
1781 | |
|
|
1782 | The rationale for installing a no-op handler as opposed to ignoring it is |
|
|
1783 | that this way, the handler will be restored to defaults on exec. |
|
|
1784 | |
|
|
1785 | Feel free to install your own handler, or reset it to defaults. |
|
|
1786 | |
|
|
1787 | =back |
|
|
1788 | |
|
|
1789 | =cut |
|
|
1790 | |
|
|
1791 | $SIG{PIPE} = sub { } |
|
|
1792 | unless defined $SIG{PIPE}; |
|
|
1793 | |
|
|
1794 | |
|
|
1795 | =head1 FORK |
|
|
1796 | |
|
|
1797 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1798 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1799 | calls. Only L<EV> is fully fork-aware. |
|
|
1800 | |
|
|
1801 | If you have to fork, you must either do so I<before> creating your first |
|
|
1802 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1803 | |
|
|
1804 | |
|
|
1805 | =head1 SECURITY CONSIDERATIONS |
|
|
1806 | |
|
|
1807 | AnyEvent can be forced to load any event model via |
|
|
1808 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1809 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1810 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1811 | will not be active when the program uses a different event model than |
|
|
1812 | specified in the variable. |
|
|
1813 | |
|
|
1814 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1815 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1816 | |
|
|
1817 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1818 | |
|
|
1819 | use AnyEvent; |
|
|
1820 | |
|
|
1821 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1822 | be used to probe what backend is used and gain other information (which is |
|
|
1823 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and |
|
|
1824 | $ENV{PERL_ANYEGENT_STRICT}. |
|
|
1825 | |
|
|
1826 | |
|
|
1827 | =head1 BUGS |
|
|
1828 | |
|
|
1829 | Perl 5.8 has numerous memleaks that sometimes hit this module and are hard |
|
|
1830 | to work around. If you suffer from memleaks, first upgrade to Perl 5.10 |
|
|
1831 | and check wether the leaks still show up. (Perl 5.10.0 has other annoying |
|
|
1832 | mamleaks, such as leaking on C<map> and C<grep> but it is usually not as |
|
|
1833 | pronounced). |
|
|
1834 | |
612 | |
1835 | |
613 | =head1 SEE ALSO |
1836 | =head1 SEE ALSO |
614 | |
1837 | |
615 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
1838 | Utility functions: L<AnyEvent::Util>. |
616 | |
1839 | |
617 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
1840 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
|
|
1841 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
618 | |
1842 | |
619 | Nontrivial usage example: L<Net::FCP>. |
1843 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
|
|
1844 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
1845 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
1846 | L<AnyEvent::Impl::POE>. |
620 | |
1847 | |
621 | =head1 |
1848 | Non-blocking file handles, sockets, TCP clients and |
|
|
1849 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1850 | |
|
|
1851 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1852 | |
|
|
1853 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1854 | |
|
|
1855 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
|
|
1856 | |
|
|
1857 | |
|
|
1858 | =head1 AUTHOR |
|
|
1859 | |
|
|
1860 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1861 | http://home.schmorp.de/ |
622 | |
1862 | |
623 | =cut |
1863 | =cut |
624 | |
1864 | |
625 | 1 |
1865 | 1 |
626 | |
1866 | |