1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - the DBI of event loop programming |
3 | |
3 | |
4 | Event, Coro, Glib, Tk, Perl - various supported event loops |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, |
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5 | Qt, FLTK and POE are various supported event loops/environments. |
5 | |
6 | |
6 | SYNOPSIS |
7 | SYNOPSIS |
7 | use AnyEvent; |
8 | use AnyEvent; |
8 | |
9 | |
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10 | # if you prefer function calls, look at the AE manpage for |
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11 | # an alternative API. |
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12 | |
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13 | # file handle or descriptor readable |
9 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
14 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
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15 | |
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16 | # one-shot or repeating timers |
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17 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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18 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...); |
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19 | |
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20 | print AnyEvent->now; # prints current event loop time |
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21 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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22 | |
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23 | # POSIX signal |
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24 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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25 | |
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26 | # child process exit |
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27 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
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28 | my ($pid, $status) = @_; |
10 | ... |
29 | ... |
11 | }); |
30 | }); |
12 | |
31 | |
13 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
32 | # called when event loop idle (if applicable) |
14 | ... |
33 | my $w = AnyEvent->idle (cb => sub { ... }); |
15 | }); |
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16 | |
34 | |
17 | my $w = AnyEvent->condvar; # stores wether a condition was flagged |
35 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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36 | $w->send; # wake up current and all future recv's |
18 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
37 | $w->recv; # enters "main loop" till $condvar gets ->send |
19 | $w->broadcast; # wake up current and all future wait's |
38 | # use a condvar in callback mode: |
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39 | $w->cb (sub { $_[0]->recv }); |
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40 | |
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41 | INTRODUCTION/TUTORIAL |
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42 | This manpage is mainly a reference manual. If you are interested in a |
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43 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
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44 | manpage. |
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45 | |
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46 | SUPPORT |
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47 | An FAQ document is available as AnyEvent::FAQ. |
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48 | |
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49 | There also is a mailinglist for discussing all things AnyEvent, and an |
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50 | IRC channel, too. |
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51 | |
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52 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
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53 | Repository, at <http://anyevent.schmorp.de>, for more info. |
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54 | |
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55 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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56 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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57 | nowadays. So what is different about AnyEvent? |
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58 | |
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59 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
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60 | policy* and AnyEvent is *small and efficient*. |
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61 | |
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62 | First and foremost, *AnyEvent is not an event model* itself, it only |
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63 | interfaces to whatever event model the main program happens to use, in a |
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64 | pragmatic way. For event models and certain classes of immortals alike, |
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65 | the statement "there can only be one" is a bitter reality: In general, |
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66 | only one event loop can be active at the same time in a process. |
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67 | AnyEvent cannot change this, but it can hide the differences between |
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68 | those event loops. |
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69 | |
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70 | The goal of AnyEvent is to offer module authors the ability to do event |
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71 | programming (waiting for I/O or timer events) without subscribing to a |
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72 | religion, a way of living, and most importantly: without forcing your |
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73 | module users into the same thing by forcing them to use the same event |
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74 | model you use. |
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75 | |
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76 | For modules like POE or IO::Async (which is a total misnomer as it is |
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77 | actually doing all I/O *synchronously*...), using them in your module is |
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78 | like joining a cult: After you join, you are dependent on them and you |
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79 | cannot use anything else, as they are simply incompatible to everything |
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80 | that isn't them. What's worse, all the potential users of your module |
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81 | are *also* forced to use the same event loop you use. |
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82 | |
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83 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
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84 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
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85 | with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module |
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86 | uses one of those, every user of your module has to use it, too. But if |
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87 | your module uses AnyEvent, it works transparently with all event models |
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88 | it supports (including stuff like IO::Async, as long as those use one of |
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89 | the supported event loops. It is easy to add new event loops to |
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90 | AnyEvent, too, so it is future-proof). |
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91 | |
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92 | In addition to being free of having to use *the one and only true event |
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93 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
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94 | modules, you get an enormous amount of code and strict rules you have to |
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95 | follow. AnyEvent, on the other hand, is lean and to the point, by only |
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96 | offering the functionality that is necessary, in as thin as a wrapper as |
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97 | technically possible. |
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98 | |
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99 | Of course, AnyEvent comes with a big (and fully optional!) toolbox of |
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100 | useful functionality, such as an asynchronous DNS resolver, 100% |
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101 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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102 | such as Windows) and lots of real-world knowledge and workarounds for |
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103 | platform bugs and differences. |
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104 | |
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105 | Now, if you *do want* lots of policy (this can arguably be somewhat |
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106 | useful) and you want to force your users to use the one and only event |
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107 | model, you should *not* use this module. |
20 | |
108 | |
21 | DESCRIPTION |
109 | DESCRIPTION |
22 | AnyEvent provides an identical interface to multiple event loops. This |
110 | AnyEvent provides a uniform interface to various event loops. This |
23 | allows module authors to utilise an event loop without forcing module |
111 | allows module authors to use event loop functionality without forcing |
24 | users to use the same event loop (as only a single event loop can |
112 | module users to use a specific event loop implementation (since more |
25 | coexist peacefully at any one time). |
113 | than one event loop cannot coexist peacefully). |
26 | |
114 | |
27 | The interface itself is vaguely similar but not identical to the Event |
115 | The interface itself is vaguely similar, but not identical to the Event |
28 | module. |
116 | module. |
29 | |
117 | |
30 | On the first call of any method, the module tries to detect the |
118 | During the first call of any watcher-creation method, the module tries |
31 | currently loaded event loop by probing wether any of the following |
119 | to detect the currently loaded event loop by probing whether one of the |
32 | modules is loaded: Coro::Event, Event, Glib, Tk. The first one found is |
120 | following modules is already loaded: EV, AnyEvent::Loop, Event, Glib, |
33 | used. If none is found, the module tries to load these modules in the |
121 | Tk, Event::Lib, Qt, POE. The first one found is used. If none are |
34 | order given. The first one that could be successfully loaded will be |
122 | detected, the module tries to load the first four modules in the order |
35 | used. If still none could be found, AnyEvent will fall back to a |
123 | given; but note that if EV is not available, the pure-perl |
36 | pure-perl event loop, which is also not very efficient. |
124 | AnyEvent::Loop should always work, so the other two are not normally |
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125 | tried. |
37 | |
126 | |
38 | Because AnyEvent first checks for modules that are already loaded, |
127 | Because AnyEvent first checks for modules that are already loaded, |
39 | loading an Event model explicitly before first using AnyEvent will |
128 | loading an event model explicitly before first using AnyEvent will |
40 | likely make that model the default. For example: |
129 | likely make that model the default. For example: |
41 | |
130 | |
42 | use Tk; |
131 | use Tk; |
43 | use AnyEvent; |
132 | use AnyEvent; |
44 | |
133 | |
45 | # .. AnyEvent will likely default to Tk |
134 | # .. AnyEvent will likely default to Tk |
46 | |
135 | |
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136 | The *likely* means that, if any module loads another event model and |
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137 | starts using it, all bets are off - this case should be very rare |
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138 | though, as very few modules hardcode event loops without announcing this |
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139 | very loudly. |
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140 | |
47 | The pure-perl implementation of AnyEvent is called |
141 | The pure-perl implementation of AnyEvent is called "AnyEvent::Loop". |
48 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
142 | Like other event modules you can load it explicitly and enjoy the high |
49 | explicitly. |
143 | availability of that event loop :) |
50 | |
144 | |
51 | WATCHERS |
145 | WATCHERS |
52 | AnyEvent has the central concept of a *watcher*, which is an object that |
146 | AnyEvent has the central concept of a *watcher*, which is an object that |
53 | stores relevant data for each kind of event you are waiting for, such as |
147 | stores relevant data for each kind of event you are waiting for, such as |
54 | the callback to call, the filehandle to watch, etc. |
148 | the callback to call, the file handle to watch, etc. |
55 | |
149 | |
56 | These watchers are normal Perl objects with normal Perl lifetime. After |
150 | These watchers are normal Perl objects with normal Perl lifetime. After |
57 | creating a watcher it will immediately "watch" for events and invoke the |
151 | creating a watcher it will immediately "watch" for events and invoke the |
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152 | callback when the event occurs (of course, only when the event model is |
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153 | in control). |
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154 | |
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155 | Note that callbacks must not permanently change global variables |
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156 | potentially in use by the event loop (such as $_ or $[) and that |
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157 | callbacks must not "die". The former is good programming practice in |
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158 | Perl and the latter stems from the fact that exception handling differs |
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159 | widely between event loops. |
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160 | |
58 | callback. To disable the watcher you have to destroy it (e.g. by setting |
161 | To disable a watcher you have to destroy it (e.g. by setting the |
59 | the variable that stores it to "undef" or otherwise deleting all |
162 | variable you store it in to "undef" or otherwise deleting all references |
60 | references to it). |
163 | to it). |
61 | |
164 | |
62 | All watchers are created by calling a method on the "AnyEvent" class. |
165 | All watchers are created by calling a method on the "AnyEvent" class. |
63 | |
166 | |
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167 | Many watchers either are used with "recursion" (repeating timers for |
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168 | example), or need to refer to their watcher object in other ways. |
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169 | |
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170 | One way to achieve that is this pattern: |
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171 | |
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172 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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173 | # you can use $w here, for example to undef it |
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174 | undef $w; |
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175 | }); |
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176 | |
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177 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
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178 | my variables are only visible after the statement in which they are |
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179 | declared. |
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180 | |
64 | IO WATCHERS |
181 | I/O WATCHERS |
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182 | $w = AnyEvent->io ( |
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183 | fh => <filehandle_or_fileno>, |
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184 | poll => <"r" or "w">, |
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185 | cb => <callback>, |
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186 | ); |
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187 | |
65 | You can create I/O watcher by calling the "AnyEvent->io" method with the |
188 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
66 | following mandatory arguments: |
189 | the following mandatory key-value pairs as arguments: |
67 | |
190 | |
68 | "fh" the Perl *filehandle* (not filedescriptor) to watch for events. |
191 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
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192 | events (AnyEvent might or might not keep a reference to this file |
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193 | handle). Note that only file handles pointing to things for which |
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194 | non-blocking operation makes sense are allowed. This includes sockets, |
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195 | most character devices, pipes, fifos and so on, but not for example |
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196 | files or block devices. |
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197 | |
69 | "poll" must be a string that is either "r" or "w", that creates a |
198 | "poll" must be a string that is either "r" or "w", which creates a |
70 | watcher waiting for "r"eadable or "w"ritable events. "cb" teh callback |
199 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
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200 | |
71 | to invoke everytime the filehandle becomes ready. |
201 | "cb" is the callback to invoke each time the file handle becomes ready. |
72 | |
202 | |
73 | Only one io watcher per "fh" and "poll" combination is allowed (i.e. on |
203 | Although the callback might get passed parameters, their value and |
74 | a socket you can have one r + one w, not any more (limitation comes from |
204 | presence is undefined and you cannot rely on them. Portable AnyEvent |
75 | Tk - if you are sure you are not using Tk this limitation is gone). |
205 | callbacks cannot use arguments passed to I/O watcher callbacks. |
76 | |
206 | |
77 | Filehandles will be kept alive, so as long as the watcher exists, the |
207 | The I/O watcher might use the underlying file descriptor or a copy of |
78 | filehandle exists, too. |
208 | it. You must not close a file handle as long as any watcher is active on |
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209 | the underlying file descriptor. |
79 | |
210 | |
80 | Example: |
211 | Some event loops issue spurious readiness notifications, so you should |
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212 | always use non-blocking calls when reading/writing from/to your file |
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213 | handles. |
81 | |
214 | |
82 | # wait for readability of STDIN, then read a line and disable the watcher |
215 | Example: wait for readability of STDIN, then read a line and disable the |
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216 | watcher. |
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217 | |
83 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
218 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
84 | chomp (my $input = <STDIN>); |
219 | chomp (my $input = <STDIN>); |
85 | warn "read: $input\n"; |
220 | warn "read: $input\n"; |
86 | undef $w; |
221 | undef $w; |
87 | }); |
222 | }); |
88 | |
223 | |
89 | TIMER WATCHERS |
224 | TIME WATCHERS |
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225 | $w = AnyEvent->timer (after => <seconds>, cb => <callback>); |
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226 | |
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227 | $w = AnyEvent->timer ( |
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228 | after => <fractional_seconds>, |
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229 | interval => <fractional_seconds>, |
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230 | cb => <callback>, |
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231 | ); |
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232 | |
90 | You can create a timer watcher by calling the "AnyEvent->timer" method |
233 | You can create a time watcher by calling the "AnyEvent->timer" method |
91 | with the following mandatory arguments: |
234 | with the following mandatory arguments: |
92 | |
235 | |
93 | "after" after how many seconds (fractions are supported) should the |
236 | "after" specifies after how many seconds (fractional values are |
94 | timer activate. "cb" the callback to invoke. |
237 | supported) the callback should be invoked. "cb" is the callback to |
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238 | invoke in that case. |
95 | |
239 | |
96 | The timer callback will be invoked at most once: if you want a repeating |
240 | Although the callback might get passed parameters, their value and |
97 | timer you have to create a new watcher (this is a limitation by both Tk |
241 | presence is undefined and you cannot rely on them. Portable AnyEvent |
98 | and Glib). |
242 | callbacks cannot use arguments passed to time watcher callbacks. |
99 | |
243 | |
100 | Example: |
244 | The callback will normally be invoked only once. If you specify another |
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245 | parameter, "interval", as a strictly positive number (> 0), then the |
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246 | callback will be invoked regularly at that interval (in fractional |
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247 | seconds) after the first invocation. If "interval" is specified with a |
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248 | false value, then it is treated as if it were not specified at all. |
101 | |
249 | |
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250 | The callback will be rescheduled before invoking the callback, but no |
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251 | attempt is made to avoid timer drift in most backends, so the interval |
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252 | is only approximate. |
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253 | |
102 | # fire an event after 7.7 seconds |
254 | Example: fire an event after 7.7 seconds. |
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255 | |
103 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
256 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
104 | warn "timeout\n"; |
257 | warn "timeout\n"; |
105 | }); |
258 | }); |
106 | |
259 | |
107 | # to cancel the timer: |
260 | # to cancel the timer: |
108 | undef $w |
261 | undef $w; |
109 | |
262 | |
110 | CONDITION WATCHERS |
263 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
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264 | |
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265 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
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266 | warn "timeout\n"; |
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267 | }); |
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268 | |
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269 | TIMING ISSUES |
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270 | There are two ways to handle timers: based on real time (relative, "fire |
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271 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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272 | o'clock"). |
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273 | |
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274 | While most event loops expect timers to specified in a relative way, |
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275 | they use absolute time internally. This makes a difference when your |
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276 | clock "jumps", for example, when ntp decides to set your clock backwards |
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277 | from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is |
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278 | supposed to fire "after a second" might actually take six years to |
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279 | finally fire. |
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280 | |
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281 | AnyEvent cannot compensate for this. The only event loop that is |
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282 | conscious of these issues is EV, which offers both relative (ev_timer, |
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283 | based on true relative time) and absolute (ev_periodic, based on |
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284 | wallclock time) timers. |
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285 | |
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286 | AnyEvent always prefers relative timers, if available, matching the |
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287 | AnyEvent API. |
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288 | |
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289 | AnyEvent has two additional methods that return the "current time": |
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290 | |
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291 | AnyEvent->time |
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292 | This returns the "current wallclock time" as a fractional number of |
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293 | seconds since the Epoch (the same thing as "time" or |
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294 | "Time::HiRes::time" return, and the result is guaranteed to be |
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295 | compatible with those). |
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296 | |
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297 | It progresses independently of any event loop processing, i.e. each |
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298 | call will check the system clock, which usually gets updated |
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299 | frequently. |
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300 | |
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301 | AnyEvent->now |
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302 | This also returns the "current wallclock time", but unlike "time", |
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303 | above, this value might change only once per event loop iteration, |
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304 | depending on the event loop (most return the same time as "time", |
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305 | above). This is the time that AnyEvent's timers get scheduled |
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306 | against. |
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307 | |
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308 | *In almost all cases (in all cases if you don't care), this is the |
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309 | function to call when you want to know the current time.* |
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310 | |
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311 | This function is also often faster then "AnyEvent->time", and thus |
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312 | the preferred method if you want some timestamp (for example, |
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313 | AnyEvent::Handle uses this to update its activity timeouts). |
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314 | |
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315 | The rest of this section is only of relevance if you try to be very |
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316 | exact with your timing; you can skip it without a bad conscience. |
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317 | |
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318 | For a practical example of when these times differ, consider |
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319 | Event::Lib and EV and the following set-up: |
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320 | |
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321 | The event loop is running and has just invoked one of your callbacks |
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322 | at time=500 (assume no other callbacks delay processing). In your |
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323 | callback, you wait a second by executing "sleep 1" (blocking the |
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324 | process for a second) and then (at time=501) you create a relative |
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325 | timer that fires after three seconds. |
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326 | |
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327 | With Event::Lib, "AnyEvent->time" and "AnyEvent->now" will both |
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328 | return 501, because that is the current time, and the timer will be |
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329 | scheduled to fire at time=504 (501 + 3). |
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330 | |
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331 | With EV, "AnyEvent->time" returns 501 (as that is the current time), |
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332 | but "AnyEvent->now" returns 500, as that is the time the last event |
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333 | processing phase started. With EV, your timer gets scheduled to run |
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334 | at time=503 (500 + 3). |
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335 | |
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336 | In one sense, Event::Lib is more exact, as it uses the current time |
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337 | regardless of any delays introduced by event processing. However, |
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338 | most callbacks do not expect large delays in processing, so this |
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339 | causes a higher drift (and a lot more system calls to get the |
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340 | current time). |
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341 | |
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342 | In another sense, EV is more exact, as your timer will be scheduled |
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343 | at the same time, regardless of how long event processing actually |
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344 | took. |
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345 | |
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346 | In either case, if you care (and in most cases, you don't), then you |
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347 | can get whatever behaviour you want with any event loop, by taking |
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348 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
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349 | account. |
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350 | |
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351 | AnyEvent->now_update |
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352 | Some event loops (such as EV or AnyEvent::Loop) cache the current |
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353 | time for each loop iteration (see the discussion of AnyEvent->now, |
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354 | above). |
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355 | |
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356 | When a callback runs for a long time (or when the process sleeps), |
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357 | then this "current" time will differ substantially from the real |
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358 | time, which might affect timers and time-outs. |
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359 | |
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360 | When this is the case, you can call this method, which will update |
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361 | the event loop's idea of "current time". |
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362 | |
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363 | A typical example would be a script in a web server (e.g. |
|
|
364 | "mod_perl") - when mod_perl executes the script, then the event loop |
|
|
365 | will have the wrong idea about the "current time" (being potentially |
|
|
366 | far in the past, when the script ran the last time). In that case |
|
|
367 | you should arrange a call to "AnyEvent->now_update" each time the |
|
|
368 | web server process wakes up again (e.g. at the start of your script, |
|
|
369 | or in a handler). |
|
|
370 | |
|
|
371 | Note that updating the time *might* cause some events to be handled. |
|
|
372 | |
|
|
373 | SIGNAL WATCHERS |
|
|
374 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
|
|
375 | |
|
|
376 | You can watch for signals using a signal watcher, "signal" is the signal |
|
|
377 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
|
|
378 | callback to be invoked whenever a signal occurs. |
|
|
379 | |
|
|
380 | Although the callback might get passed parameters, their value and |
|
|
381 | presence is undefined and you cannot rely on them. Portable AnyEvent |
|
|
382 | callbacks cannot use arguments passed to signal watcher callbacks. |
|
|
383 | |
|
|
384 | Multiple signal occurrences can be clumped together into one callback |
|
|
385 | invocation, and callback invocation will be synchronous. Synchronous |
|
|
386 | means that it might take a while until the signal gets handled by the |
|
|
387 | process, but it is guaranteed not to interrupt any other callbacks. |
|
|
388 | |
|
|
389 | The main advantage of using these watchers is that you can share a |
|
|
390 | signal between multiple watchers, and AnyEvent will ensure that signals |
|
|
391 | will not interrupt your program at bad times. |
|
|
392 | |
|
|
393 | This watcher might use %SIG (depending on the event loop used), so |
|
|
394 | programs overwriting those signals directly will likely not work |
|
|
395 | correctly. |
|
|
396 | |
|
|
397 | Example: exit on SIGINT |
|
|
398 | |
|
|
399 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
400 | |
|
|
401 | Restart Behaviour |
|
|
402 | While restart behaviour is up to the event loop implementation, most |
|
|
403 | will not restart syscalls (that includes Async::Interrupt and AnyEvent's |
|
|
404 | pure perl implementation). |
|
|
405 | |
|
|
406 | Safe/Unsafe Signals |
|
|
407 | Perl signals can be either "safe" (synchronous to opcode handling) or |
|
|
408 | "unsafe" (asynchronous) - the former might delay signal delivery |
|
|
409 | indefinitely, the latter might corrupt your memory. |
|
|
410 | |
|
|
411 | AnyEvent signal handlers are, in addition, synchronous to the event |
|
|
412 | loop, i.e. they will not interrupt your running perl program but will |
|
|
413 | only be called as part of the normal event handling (just like timer, |
|
|
414 | I/O etc. callbacks, too). |
|
|
415 | |
|
|
416 | Signal Races, Delays and Workarounds |
|
|
417 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
|
|
418 | callbacks to signals in a generic way, which is a pity, as you cannot do |
|
|
419 | race-free signal handling in perl, requiring C libraries for this. |
|
|
420 | AnyEvent will try to do its best, which means in some cases, signals |
|
|
421 | will be delayed. The maximum time a signal might be delayed is 10 |
|
|
422 | seconds by default, but can be overriden via |
|
|
423 | $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} or $AnyEvent::MAX_SIGNAL_LATENCY |
|
|
424 | - see the "ENVIRONMENT VARIABLES" section for details. |
|
|
425 | |
|
|
426 | All these problems can be avoided by installing the optional |
|
|
427 | Async::Interrupt module, which works with most event loops. It will not |
|
|
428 | work with inherently broken event loops such as Event or Event::Lib (and |
|
|
429 | not with POE currently). For those, you just have to suffer the delays. |
|
|
430 | |
|
|
431 | CHILD PROCESS WATCHERS |
|
|
432 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
|
|
433 | |
|
|
434 | You can also watch for a child process exit and catch its exit status. |
|
|
435 | |
|
|
436 | The child process is specified by the "pid" argument (on some backends, |
|
|
437 | using 0 watches for any child process exit, on others this will croak). |
|
|
438 | The watcher will be triggered only when the child process has finished |
|
|
439 | and an exit status is available, not on any trace events |
|
|
440 | (stopped/continued). |
|
|
441 | |
|
|
442 | The callback will be called with the pid and exit status (as returned by |
|
|
443 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
|
|
444 | callback arguments. |
|
|
445 | |
|
|
446 | This watcher type works by installing a signal handler for "SIGCHLD", |
|
|
447 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
|
|
448 | random child processes (waiting for specific child processes, e.g. |
|
|
449 | inside "system", is just fine). |
|
|
450 | |
|
|
451 | There is a slight catch to child watchers, however: you usually start |
|
|
452 | them *after* the child process was created, and this means the process |
|
|
453 | could have exited already (and no SIGCHLD will be sent anymore). |
|
|
454 | |
|
|
455 | Not all event models handle this correctly (neither POE nor IO::Async |
|
|
456 | do, see their AnyEvent::Impl manpages for details), but even for event |
|
|
457 | models that *do* handle this correctly, they usually need to be loaded |
|
|
458 | before the process exits (i.e. before you fork in the first place). |
|
|
459 | AnyEvent's pure perl event loop handles all cases correctly regardless |
|
|
460 | of when you start the watcher. |
|
|
461 | |
|
|
462 | This means you cannot create a child watcher as the very first thing in |
|
|
463 | an AnyEvent program, you *have* to create at least one watcher before |
|
|
464 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
|
|
465 | |
|
|
466 | As most event loops do not support waiting for child events, they will |
|
|
467 | be emulated by AnyEvent in most cases, in which case the latency and |
|
|
468 | race problems mentioned in the description of signal watchers apply. |
|
|
469 | |
|
|
470 | Example: fork a process and wait for it |
|
|
471 | |
|
|
472 | my $done = AnyEvent->condvar; |
|
|
473 | |
|
|
474 | my $pid = fork or exit 5; |
|
|
475 | |
|
|
476 | my $w = AnyEvent->child ( |
|
|
477 | pid => $pid, |
|
|
478 | cb => sub { |
|
|
479 | my ($pid, $status) = @_; |
|
|
480 | warn "pid $pid exited with status $status"; |
|
|
481 | $done->send; |
|
|
482 | }, |
|
|
483 | ); |
|
|
484 | |
|
|
485 | # do something else, then wait for process exit |
|
|
486 | $done->recv; |
|
|
487 | |
|
|
488 | IDLE WATCHERS |
|
|
489 | $w = AnyEvent->idle (cb => <callback>); |
|
|
490 | |
|
|
491 | This will repeatedly invoke the callback after the process becomes idle, |
|
|
492 | until either the watcher is destroyed or new events have been detected. |
|
|
493 | |
|
|
494 | Idle watchers are useful when there is a need to do something, but it is |
|
|
495 | not so important (or wise) to do it instantly. The callback will be |
|
|
496 | invoked only when there is "nothing better to do", which is usually |
|
|
497 | defined as "all outstanding events have been handled and no new events |
|
|
498 | have been detected". That means that idle watchers ideally get invoked |
|
|
499 | when the event loop has just polled for new events but none have been |
|
|
500 | detected. Instead of blocking to wait for more events, the idle watchers |
|
|
501 | will be invoked. |
|
|
502 | |
|
|
503 | Unfortunately, most event loops do not really support idle watchers |
|
|
504 | (only EV, Event and Glib do it in a usable fashion) - for the rest, |
|
|
505 | AnyEvent will simply call the callback "from time to time". |
|
|
506 | |
|
|
507 | Example: read lines from STDIN, but only process them when the program |
|
|
508 | is otherwise idle: |
|
|
509 | |
|
|
510 | my @lines; # read data |
|
|
511 | my $idle_w; |
|
|
512 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
|
|
513 | push @lines, scalar <STDIN>; |
|
|
514 | |
|
|
515 | # start an idle watcher, if not already done |
|
|
516 | $idle_w ||= AnyEvent->idle (cb => sub { |
|
|
517 | # handle only one line, when there are lines left |
|
|
518 | if (my $line = shift @lines) { |
|
|
519 | print "handled when idle: $line"; |
|
|
520 | } else { |
|
|
521 | # otherwise disable the idle watcher again |
|
|
522 | undef $idle_w; |
|
|
523 | } |
|
|
524 | }); |
|
|
525 | }); |
|
|
526 | |
|
|
527 | CONDITION VARIABLES |
|
|
528 | $cv = AnyEvent->condvar; |
|
|
529 | |
|
|
530 | $cv->send (<list>); |
|
|
531 | my @res = $cv->recv; |
|
|
532 | |
|
|
533 | If you are familiar with some event loops you will know that all of them |
|
|
534 | require you to run some blocking "loop", "run" or similar function that |
|
|
535 | will actively watch for new events and call your callbacks. |
|
|
536 | |
|
|
537 | AnyEvent is slightly different: it expects somebody else to run the |
|
|
538 | event loop and will only block when necessary (usually when told by the |
|
|
539 | user). |
|
|
540 | |
|
|
541 | The tool to do that is called a "condition variable", so called because |
|
|
542 | they represent a condition that must become true. |
|
|
543 | |
|
|
544 | Now is probably a good time to look at the examples further below. |
|
|
545 | |
111 | Condition watchers can be created by calling the "AnyEvent->condvar" |
546 | Condition variables can be created by calling the "AnyEvent->condvar" |
112 | method without any arguments. |
547 | method, usually without arguments. The only argument pair allowed is |
|
|
548 | "cb", which specifies a callback to be called when the condition |
|
|
549 | variable becomes true, with the condition variable as the first argument |
|
|
550 | (but not the results). |
113 | |
551 | |
114 | A condition watcher watches for a condition - precisely that the |
552 | After creation, the condition variable is "false" until it becomes |
115 | "->broadcast" method has been called. |
553 | "true" by calling the "send" method (or calling the condition variable |
|
|
554 | as if it were a callback, read about the caveats in the description for |
|
|
555 | the "->send" method). |
116 | |
556 | |
117 | The watcher has only two methods: |
557 | Since condition variables are the most complex part of the AnyEvent API, |
|
|
558 | here are some different mental models of what they are - pick the ones |
|
|
559 | you can connect to: |
118 | |
560 | |
119 | $cv->wait |
561 | * Condition variables are like callbacks - you can call them (and pass |
|
|
562 | them instead of callbacks). Unlike callbacks however, you can also |
|
|
563 | wait for them to be called. |
|
|
564 | |
|
|
565 | * Condition variables are signals - one side can emit or send them, |
|
|
566 | the other side can wait for them, or install a handler that is |
|
|
567 | called when the signal fires. |
|
|
568 | |
|
|
569 | * Condition variables are like "Merge Points" - points in your program |
|
|
570 | where you merge multiple independent results/control flows into one. |
|
|
571 | |
|
|
572 | * Condition variables represent a transaction - functions that start |
|
|
573 | some kind of transaction can return them, leaving the caller the |
|
|
574 | choice between waiting in a blocking fashion, or setting a callback. |
|
|
575 | |
|
|
576 | * Condition variables represent future values, or promises to deliver |
|
|
577 | some result, long before the result is available. |
|
|
578 | |
|
|
579 | Condition variables are very useful to signal that something has |
|
|
580 | finished, for example, if you write a module that does asynchronous http |
|
|
581 | requests, then a condition variable would be the ideal candidate to |
|
|
582 | signal the availability of results. The user can either act when the |
|
|
583 | callback is called or can synchronously "->recv" for the results. |
|
|
584 | |
|
|
585 | You can also use them to simulate traditional event loops - for example, |
|
|
586 | you can block your main program until an event occurs - for example, you |
|
|
587 | could "->recv" in your main program until the user clicks the Quit |
|
|
588 | button of your app, which would "->send" the "quit" event. |
|
|
589 | |
|
|
590 | Note that condition variables recurse into the event loop - if you have |
|
|
591 | two pieces of code that call "->recv" in a round-robin fashion, you |
|
|
592 | lose. Therefore, condition variables are good to export to your caller, |
|
|
593 | but you should avoid making a blocking wait yourself, at least in |
|
|
594 | callbacks, as this asks for trouble. |
|
|
595 | |
|
|
596 | Condition variables are represented by hash refs in perl, and the keys |
|
|
597 | used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy |
|
|
598 | (it is often useful to build your own transaction class on top of |
|
|
599 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
|
|
600 | its "new" method in your own "new" method. |
|
|
601 | |
|
|
602 | There are two "sides" to a condition variable - the "producer side" |
|
|
603 | which eventually calls "-> send", and the "consumer side", which waits |
|
|
604 | for the send to occur. |
|
|
605 | |
|
|
606 | Example: wait for a timer. |
|
|
607 | |
|
|
608 | # condition: "wait till the timer is fired" |
|
|
609 | my $timer_fired = AnyEvent->condvar; |
|
|
610 | |
|
|
611 | # create the timer - we could wait for, say |
|
|
612 | # a handle becomign ready, or even an |
|
|
613 | # AnyEvent::HTTP request to finish, but |
|
|
614 | # in this case, we simply use a timer: |
|
|
615 | my $w = AnyEvent->timer ( |
|
|
616 | after => 1, |
|
|
617 | cb => sub { $timer_fired->send }, |
|
|
618 | ); |
|
|
619 | |
|
|
620 | # this "blocks" (while handling events) till the callback |
|
|
621 | # calls ->send |
|
|
622 | $timer_fired->recv; |
|
|
623 | |
|
|
624 | Example: wait for a timer, but take advantage of the fact that condition |
|
|
625 | variables are also callable directly. |
|
|
626 | |
|
|
627 | my $done = AnyEvent->condvar; |
|
|
628 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
|
|
629 | $done->recv; |
|
|
630 | |
|
|
631 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
632 | callbacks. This is how you make a synchronous call, for example from the |
|
|
633 | main program: |
|
|
634 | |
|
|
635 | use AnyEvent::CouchDB; |
|
|
636 | |
|
|
637 | ... |
|
|
638 | |
|
|
639 | my @info = $couchdb->info->recv; |
|
|
640 | |
|
|
641 | And this is how you would just set a callback to be called whenever the |
|
|
642 | results are available: |
|
|
643 | |
|
|
644 | $couchdb->info->cb (sub { |
|
|
645 | my @info = $_[0]->recv; |
|
|
646 | }); |
|
|
647 | |
|
|
648 | METHODS FOR PRODUCERS |
|
|
649 | These methods should only be used by the producing side, i.e. the |
|
|
650 | code/module that eventually sends the signal. Note that it is also the |
|
|
651 | producer side which creates the condvar in most cases, but it isn't |
|
|
652 | uncommon for the consumer to create it as well. |
|
|
653 | |
|
|
654 | $cv->send (...) |
|
|
655 | Flag the condition as ready - a running "->recv" and all further |
|
|
656 | calls to "recv" will (eventually) return after this method has been |
|
|
657 | called. If nobody is waiting the send will be remembered. |
|
|
658 | |
|
|
659 | If a callback has been set on the condition variable, it is called |
|
|
660 | immediately from within send. |
|
|
661 | |
|
|
662 | Any arguments passed to the "send" call will be returned by all |
|
|
663 | future "->recv" calls. |
|
|
664 | |
|
|
665 | Condition variables are overloaded so one can call them directly (as |
|
|
666 | if they were a code reference). Calling them directly is the same as |
|
|
667 | calling "send". |
|
|
668 | |
|
|
669 | $cv->croak ($error) |
|
|
670 | Similar to send, but causes all calls to "->recv" to invoke |
|
|
671 | "Carp::croak" with the given error message/object/scalar. |
|
|
672 | |
|
|
673 | This can be used to signal any errors to the condition variable |
|
|
674 | user/consumer. Doing it this way instead of calling "croak" directly |
|
|
675 | delays the error detection, but has the overwhelming advantage that |
|
|
676 | it diagnoses the error at the place where the result is expected, |
|
|
677 | and not deep in some event callback with no connection to the actual |
|
|
678 | code causing the problem. |
|
|
679 | |
|
|
680 | $cv->begin ([group callback]) |
|
|
681 | $cv->end |
|
|
682 | These two methods can be used to combine many transactions/events |
|
|
683 | into one. For example, a function that pings many hosts in parallel |
|
|
684 | might want to use a condition variable for the whole process. |
|
|
685 | |
|
|
686 | Every call to "->begin" will increment a counter, and every call to |
|
|
687 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
|
|
688 | (last) callback passed to "begin" will be executed, passing the |
|
|
689 | condvar as first argument. That callback is *supposed* to call |
|
|
690 | "->send", but that is not required. If no group callback was set, |
|
|
691 | "send" will be called without any arguments. |
|
|
692 | |
|
|
693 | You can think of "$cv->send" giving you an OR condition (one call |
|
|
694 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
|
|
695 | condition (all "begin" calls must be "end"'ed before the condvar |
|
|
696 | sends). |
|
|
697 | |
|
|
698 | Let's start with a simple example: you have two I/O watchers (for |
|
|
699 | example, STDOUT and STDERR for a program), and you want to wait for |
|
|
700 | both streams to close before activating a condvar: |
|
|
701 | |
|
|
702 | my $cv = AnyEvent->condvar; |
|
|
703 | |
|
|
704 | $cv->begin; # first watcher |
|
|
705 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
|
|
706 | defined sysread $fh1, my $buf, 4096 |
|
|
707 | or $cv->end; |
|
|
708 | }); |
|
|
709 | |
|
|
710 | $cv->begin; # second watcher |
|
|
711 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
|
|
712 | defined sysread $fh2, my $buf, 4096 |
|
|
713 | or $cv->end; |
|
|
714 | }); |
|
|
715 | |
|
|
716 | $cv->recv; |
|
|
717 | |
|
|
718 | This works because for every event source (EOF on file handle), |
|
|
719 | there is one call to "begin", so the condvar waits for all calls to |
|
|
720 | "end" before sending. |
|
|
721 | |
|
|
722 | The ping example mentioned above is slightly more complicated, as |
|
|
723 | the there are results to be passwd back, and the number of tasks |
|
|
724 | that are begun can potentially be zero: |
|
|
725 | |
|
|
726 | my $cv = AnyEvent->condvar; |
|
|
727 | |
|
|
728 | my %result; |
|
|
729 | $cv->begin (sub { shift->send (\%result) }); |
|
|
730 | |
|
|
731 | for my $host (@list_of_hosts) { |
|
|
732 | $cv->begin; |
|
|
733 | ping_host_then_call_callback $host, sub { |
|
|
734 | $result{$host} = ...; |
|
|
735 | $cv->end; |
|
|
736 | }; |
|
|
737 | } |
|
|
738 | |
|
|
739 | $cv->end; |
|
|
740 | |
|
|
741 | ... |
|
|
742 | |
|
|
743 | my $results = $cv->recv; |
|
|
744 | |
|
|
745 | This code fragment supposedly pings a number of hosts and calls |
|
|
746 | "send" after results for all then have have been gathered - in any |
|
|
747 | order. To achieve this, the code issues a call to "begin" when it |
|
|
748 | starts each ping request and calls "end" when it has received some |
|
|
749 | result for it. Since "begin" and "end" only maintain a counter, the |
|
|
750 | order in which results arrive is not relevant. |
|
|
751 | |
|
|
752 | There is an additional bracketing call to "begin" and "end" outside |
|
|
753 | the loop, which serves two important purposes: first, it sets the |
|
|
754 | callback to be called once the counter reaches 0, and second, it |
|
|
755 | ensures that "send" is called even when "no" hosts are being pinged |
|
|
756 | (the loop doesn't execute once). |
|
|
757 | |
|
|
758 | This is the general pattern when you "fan out" into multiple (but |
|
|
759 | potentially zero) subrequests: use an outer "begin"/"end" pair to |
|
|
760 | set the callback and ensure "end" is called at least once, and then, |
|
|
761 | for each subrequest you start, call "begin" and for each subrequest |
|
|
762 | you finish, call "end". |
|
|
763 | |
|
|
764 | METHODS FOR CONSUMERS |
|
|
765 | These methods should only be used by the consuming side, i.e. the code |
|
|
766 | awaits the condition. |
|
|
767 | |
|
|
768 | $cv->recv |
120 | Wait (blocking if necessary) until the "->broadcast" method has been |
769 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
121 | called on c<$cv>, while servicing other watchers normally. |
770 | have been called on $cv, while servicing other watchers normally. |
122 | |
771 | |
|
|
772 | You can only wait once on a condition - additional calls are valid |
|
|
773 | but will return immediately. |
|
|
774 | |
|
|
775 | If an error condition has been set by calling "->croak", then this |
|
|
776 | function will call "croak". |
|
|
777 | |
|
|
778 | In list context, all parameters passed to "send" will be returned, |
|
|
779 | in scalar context only the first one will be returned. |
|
|
780 | |
|
|
781 | Note that doing a blocking wait in a callback is not supported by |
|
|
782 | any event loop, that is, recursive invocation of a blocking "->recv" |
|
|
783 | is not allowed and the "recv" call will "croak" if such a condition |
|
|
784 | is detected. This requirement can be dropped by relying on |
|
|
785 | Coro::AnyEvent , which allows you to do a blocking "->recv" from any |
|
|
786 | thread that doesn't run the event loop itself. Coro::AnyEvent is |
|
|
787 | loaded automatically when Coro is used with AnyEvent, so code does |
|
|
788 | not need to do anything special to take advantage of that: any code |
|
|
789 | that would normally block your program because it calls "recv", be |
|
|
790 | executed in an "async" thread instead without blocking other |
|
|
791 | threads. |
|
|
792 | |
123 | Not all event models support a blocking wait - some die in that |
793 | Not all event models support a blocking wait - some die in that case |
124 | case, so if you are using this from a module, never require a |
794 | (programs might want to do that to stay interactive), so *if you are |
|
|
795 | using this from a module, never require a blocking wait*. Instead, |
125 | blocking wait, but let the caller decide wether the call will block |
796 | let the caller decide whether the call will block or not (for |
126 | or not (for example, by coupling condition variables with some kind |
797 | example, by coupling condition variables with some kind of request |
127 | of request results and supporting callbacks so the caller knows that |
798 | results and supporting callbacks so the caller knows that getting |
128 | getting the result will not block, while still suppporting blockign |
799 | the result will not block, while still supporting blocking waits if |
129 | waits if the caller so desires). |
800 | the caller so desires). |
130 | |
801 | |
131 | You can only wait once on a condition - additional calls will return |
802 | You can ensure that "->recv" never blocks by setting a callback and |
132 | immediately. |
803 | only calling "->recv" from within that callback (or at a later |
|
|
804 | time). This will work even when the event loop does not support |
|
|
805 | blocking waits otherwise. |
133 | |
806 | |
134 | $cv->broadcast |
807 | $bool = $cv->ready |
135 | Flag the condition as ready - a running "->wait" and all further |
808 | Returns true when the condition is "true", i.e. whether "send" or |
136 | calls to "wait" will return after this method has been called. If |
809 | "croak" have been called. |
137 | nobody is waiting the broadcast will be remembered.. |
|
|
138 | |
810 | |
139 | Example: |
811 | $cb = $cv->cb ($cb->($cv)) |
|
|
812 | This is a mutator function that returns the callback set and |
|
|
813 | optionally replaces it before doing so. |
140 | |
814 | |
141 | # wait till the result is ready |
815 | The callback will be called when the condition becomes "true", i.e. |
142 | my $result_ready = AnyEvent->condvar; |
816 | when "send" or "croak" are called, with the only argument being the |
|
|
817 | condition variable itself. If the condition is already true, the |
|
|
818 | callback is called immediately when it is set. Calling "recv" inside |
|
|
819 | the callback or at any later time is guaranteed not to block. |
143 | |
820 | |
144 | # do something such as adding a timer |
821 | SUPPORTED EVENT LOOPS/BACKENDS |
145 | # or socket watcher the calls $result_ready->broadcast |
822 | The available backend classes are (every class has its own manpage): |
146 | # when the "result" is ready. |
|
|
147 | |
823 | |
148 | $result_ready->wait; |
824 | Backends that are autoprobed when no other event loop can be found. |
|
|
825 | EV is the preferred backend when no other event loop seems to be in |
|
|
826 | use. If EV is not installed, then AnyEvent will fall back to its own |
|
|
827 | pure-perl implementation, which is available everywhere as it comes |
|
|
828 | with AnyEvent itself. |
149 | |
829 | |
150 | GLOBALS |
830 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
|
|
831 | AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable. |
|
|
832 | |
|
|
833 | Backends that are transparently being picked up when they are used. |
|
|
834 | These will be used if they are already loaded when the first watcher |
|
|
835 | is created, in which case it is assumed that the application is |
|
|
836 | using them. This means that AnyEvent will automatically pick the |
|
|
837 | right backend when the main program loads an event module before |
|
|
838 | anything starts to create watchers. Nothing special needs to be done |
|
|
839 | by the main program. |
|
|
840 | |
|
|
841 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
842 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
|
|
843 | AnyEvent::Impl::Tk based on Tk, very broken. |
|
|
844 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
845 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
846 | AnyEvent::Impl::Irssi used when running within irssi. |
|
|
847 | AnyEvent::Impl::IOAsync based on IO::Async. |
|
|
848 | AnyEvent::Impl::Cocoa based on Cocoa::EventLoop. |
|
|
849 | AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding). |
|
|
850 | |
|
|
851 | Backends with special needs. |
|
|
852 | Qt requires the Qt::Application to be instantiated first, but will |
|
|
853 | otherwise be picked up automatically. As long as the main program |
|
|
854 | instantiates the application before any AnyEvent watchers are |
|
|
855 | created, everything should just work. |
|
|
856 | |
|
|
857 | AnyEvent::Impl::Qt based on Qt. |
|
|
858 | |
|
|
859 | Event loops that are indirectly supported via other backends. |
|
|
860 | Some event loops can be supported via other modules: |
|
|
861 | |
|
|
862 | There is no direct support for WxWidgets (Wx) or Prima. |
|
|
863 | |
|
|
864 | WxWidgets has no support for watching file handles. However, you can |
|
|
865 | use WxWidgets through the POE adaptor, as POE has a Wx backend that |
|
|
866 | simply polls 20 times per second, which was considered to be too |
|
|
867 | horrible to even consider for AnyEvent. |
|
|
868 | |
|
|
869 | Prima is not supported as nobody seems to be using it, but it has a |
|
|
870 | POE backend, so it can be supported through POE. |
|
|
871 | |
|
|
872 | AnyEvent knows about both Prima and Wx, however, and will try to |
|
|
873 | load POE when detecting them, in the hope that POE will pick them |
|
|
874 | up, in which case everything will be automatic. |
|
|
875 | |
|
|
876 | GLOBAL VARIABLES AND FUNCTIONS |
|
|
877 | These are not normally required to use AnyEvent, but can be useful to |
|
|
878 | write AnyEvent extension modules. |
|
|
879 | |
151 | $AnyEvent::MODEL |
880 | $AnyEvent::MODEL |
152 | Contains "undef" until the first watcher is being created. Then it |
881 | Contains "undef" until the first watcher is being created, before |
|
|
882 | the backend has been autodetected. |
|
|
883 | |
153 | contains the event model that is being used, which is the name of |
884 | Afterwards it contains the event model that is being used, which is |
154 | the Perl class implementing the model. This class is usually one of |
885 | the name of the Perl class implementing the model. This class is |
155 | the "AnyEvent::Impl:xxx" modules, but can be any other class in the |
886 | usually one of the "AnyEvent::Impl::xxx" modules, but can be any |
156 | case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). |
887 | other class in the case AnyEvent has been extended at runtime (e.g. |
|
|
888 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
157 | |
889 | |
158 | The known classes so far are: |
890 | AnyEvent::detect |
|
|
891 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
|
|
892 | if necessary. You should only call this function right before you |
|
|
893 | would have created an AnyEvent watcher anyway, that is, as late as |
|
|
894 | possible at runtime, and not e.g. during initialisation of your |
|
|
895 | module. |
159 | |
896 | |
160 | AnyEvent::Impl::Coro based on Coro::Event, best choise. |
897 | The effect of calling this function is as if a watcher had been |
161 | AnyEvent::Impl::Event based on Event, also best choice :) |
898 | created (specifically, actions that happen "when the first watcher |
162 | AnyEvent::Impl::Glib based on Glib, second-best choice. |
899 | is created" happen when calling detetc as well). |
163 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
900 | |
164 | AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
901 | If you need to do some initialisation before AnyEvent watchers are |
|
|
902 | created, use "post_detect". |
|
|
903 | |
|
|
904 | $guard = AnyEvent::post_detect { BLOCK } |
|
|
905 | Arranges for the code block to be executed as soon as the event |
|
|
906 | model is autodetected (or immediately if that has already happened). |
|
|
907 | |
|
|
908 | The block will be executed *after* the actual backend has been |
|
|
909 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
|
|
910 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
|
|
911 | other initialisations - see the sources of AnyEvent::Strict or |
|
|
912 | AnyEvent::AIO to see how this is used. |
|
|
913 | |
|
|
914 | The most common usage is to create some global watchers, without |
|
|
915 | forcing event module detection too early, for example, AnyEvent::AIO |
|
|
916 | creates and installs the global IO::AIO watcher in a "post_detect" |
|
|
917 | block to avoid autodetecting the event module at load time. |
|
|
918 | |
|
|
919 | If called in scalar or list context, then it creates and returns an |
|
|
920 | object that automatically removes the callback again when it is |
|
|
921 | destroyed (or "undef" when the hook was immediately executed). See |
|
|
922 | AnyEvent::AIO for a case where this is useful. |
|
|
923 | |
|
|
924 | Example: Create a watcher for the IO::AIO module and store it in |
|
|
925 | $WATCHER, but do so only do so after the event loop is initialised. |
|
|
926 | |
|
|
927 | our WATCHER; |
|
|
928 | |
|
|
929 | my $guard = AnyEvent::post_detect { |
|
|
930 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
|
|
931 | }; |
|
|
932 | |
|
|
933 | # the ||= is important in case post_detect immediately runs the block, |
|
|
934 | # as to not clobber the newly-created watcher. assigning both watcher and |
|
|
935 | # post_detect guard to the same variable has the advantage of users being |
|
|
936 | # able to just C<undef $WATCHER> if the watcher causes them grief. |
|
|
937 | |
|
|
938 | $WATCHER ||= $guard; |
|
|
939 | |
|
|
940 | @AnyEvent::post_detect |
|
|
941 | If there are any code references in this array (you can "push" to it |
|
|
942 | before or after loading AnyEvent), then they will be called directly |
|
|
943 | after the event loop has been chosen. |
|
|
944 | |
|
|
945 | You should check $AnyEvent::MODEL before adding to this array, |
|
|
946 | though: if it is defined then the event loop has already been |
|
|
947 | detected, and the array will be ignored. |
|
|
948 | |
|
|
949 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
|
|
950 | allows it, as it takes care of these details. |
|
|
951 | |
|
|
952 | This variable is mainly useful for modules that can do something |
|
|
953 | useful when AnyEvent is used and thus want to know when it is |
|
|
954 | initialised, but do not need to even load it by default. This array |
|
|
955 | provides the means to hook into AnyEvent passively, without loading |
|
|
956 | it. |
|
|
957 | |
|
|
958 | Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used |
|
|
959 | together, you could put this into Coro (this is the actual code used |
|
|
960 | by Coro to accomplish this): |
|
|
961 | |
|
|
962 | if (defined $AnyEvent::MODEL) { |
|
|
963 | # AnyEvent already initialised, so load Coro::AnyEvent |
|
|
964 | require Coro::AnyEvent; |
|
|
965 | } else { |
|
|
966 | # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent |
|
|
967 | # as soon as it is |
|
|
968 | push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; |
|
|
969 | } |
|
|
970 | |
|
|
971 | AnyEvent::postpone { BLOCK } |
|
|
972 | Arranges for the block to be executed as soon as possible, but not |
|
|
973 | before the call itself returns. In practise, the block will be |
|
|
974 | executed just before the event loop polls for new events, or shortly |
|
|
975 | afterwards. |
|
|
976 | |
|
|
977 | This function never returns anything (to make the "return postpone { |
|
|
978 | ... }" idiom more useful. |
|
|
979 | |
|
|
980 | To understand the usefulness of this function, consider a function |
|
|
981 | that asynchronously does something for you and returns some |
|
|
982 | transaction object or guard to let you cancel the operation. For |
|
|
983 | example, "AnyEvent::Socket::tcp_connect": |
|
|
984 | |
|
|
985 | # start a conenction attempt unless one is active |
|
|
986 | $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub { |
|
|
987 | delete $self->{connect_guard}; |
|
|
988 | ... |
|
|
989 | }; |
|
|
990 | |
|
|
991 | Imagine that this function could instantly call the callback, for |
|
|
992 | example, because it detects an obvious error such as a negative port |
|
|
993 | number. Invoking the callback before the function returns causes |
|
|
994 | problems however: the callback will be called and will try to delete |
|
|
995 | the guard object. But since the function hasn't returned yet, there |
|
|
996 | is nothing to delete. When the function eventually returns it will |
|
|
997 | assign the guard object to "$self->{connect_guard}", where it will |
|
|
998 | likely never be deleted, so the program thinks it is still trying to |
|
|
999 | connect. |
|
|
1000 | |
|
|
1001 | This is where "AnyEvent::postpone" should be used. Instead of |
|
|
1002 | calling the callback directly on error: |
|
|
1003 | |
|
|
1004 | $cb->(undef), return # signal error to callback, BAD! |
|
|
1005 | if $some_error_condition; |
|
|
1006 | |
|
|
1007 | It should use "postpone": |
|
|
1008 | |
|
|
1009 | AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later |
|
|
1010 | if $some_error_condition; |
|
|
1011 | |
|
|
1012 | AnyEvent::log $level, $msg[, @args] |
|
|
1013 | Log the given $msg at the given $level. |
|
|
1014 | |
|
|
1015 | If AnyEvent::Log is not loaded then this function makes a simple |
|
|
1016 | test to see whether the message will be logged. If the test succeeds |
|
|
1017 | it will load AnyEvent::Log and call "AnyEvent::Log::log" - |
|
|
1018 | consequently, look at the AnyEvent::Log documentation for details. |
|
|
1019 | |
|
|
1020 | If the test fails it will simply return. Right now this happens when |
|
|
1021 | a numerical loglevel is used and it is larger than the level |
|
|
1022 | specified via $ENV{PERL_ANYEVENT_VERBOSE}. |
|
|
1023 | |
|
|
1024 | If you want to sprinkle loads of logging calls around your code, |
|
|
1025 | consider creating a logger callback with the "AnyEvent::Log::logger" |
|
|
1026 | function, which can reduce typing, codesize and can reduce the |
|
|
1027 | logging overhead enourmously. |
165 | |
1028 | |
166 | WHAT TO DO IN A MODULE |
1029 | WHAT TO DO IN A MODULE |
167 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
1030 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
168 | freely, but you should not load a specific event module or rely on it. |
1031 | freely, but you should not load a specific event module or rely on it. |
169 | |
1032 | |
170 | Be careful when you create watchers in the module body - Anyevent will |
1033 | Be careful when you create watchers in the module body - AnyEvent will |
171 | decide which event module to use as soon as the first method is called, |
1034 | decide which event module to use as soon as the first method is called, |
172 | so by calling AnyEvent in your module body you force the user of your |
1035 | so by calling AnyEvent in your module body you force the user of your |
173 | module to load the event module first. |
1036 | module to load the event module first. |
174 | |
1037 | |
|
|
1038 | Never call "->recv" on a condition variable unless you *know* that the |
|
|
1039 | "->send" method has been called on it already. This is because it will |
|
|
1040 | stall the whole program, and the whole point of using events is to stay |
|
|
1041 | interactive. |
|
|
1042 | |
|
|
1043 | It is fine, however, to call "->recv" when the user of your module |
|
|
1044 | requests it (i.e. if you create a http request object ad have a method |
|
|
1045 | called "results" that returns the results, it may call "->recv" freely, |
|
|
1046 | as the user of your module knows what she is doing. Always). |
|
|
1047 | |
175 | WHAT TO DO IN THE MAIN PROGRAM |
1048 | WHAT TO DO IN THE MAIN PROGRAM |
176 | There will always be a single main program - the only place that should |
1049 | There will always be a single main program - the only place that should |
177 | dictate which event model to use. |
1050 | dictate which event model to use. |
178 | |
1051 | |
179 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
1052 | If the program is not event-based, it need not do anything special, even |
180 | do anything special and let AnyEvent decide which implementation to |
1053 | when it depends on a module that uses an AnyEvent. If the program itself |
181 | chose. |
1054 | uses AnyEvent, but does not care which event loop is used, all it needs |
|
|
1055 | to do is "use AnyEvent". In either case, AnyEvent will choose the best |
|
|
1056 | available loop implementation. |
182 | |
1057 | |
183 | If the main program relies on a specific event model (for example, in |
1058 | If the main program relies on a specific event model - for example, in |
184 | Gtk2 programs you have to rely on either Glib or Glib::Event), you |
1059 | Gtk2 programs you have to rely on the Glib module - you should load the |
185 | should load it before loading AnyEvent or any module that uses it, |
1060 | event module before loading AnyEvent or any module that uses it: |
186 | generally, as early as possible. The reason is that modules might create |
1061 | generally speaking, you should load it as early as possible. The reason |
187 | watchers when they are loaded, and AnyEvent will decide on the event |
1062 | is that modules might create watchers when they are loaded, and AnyEvent |
188 | model to use as soon as it creates watchers, and it might chose the |
1063 | will decide on the event model to use as soon as it creates watchers, |
189 | wrong one unless you load the correct one yourself. |
1064 | and it might choose the wrong one unless you load the correct one |
|
|
1065 | yourself. |
190 | |
1066 | |
191 | You can chose to use a rather inefficient pure-perl implementation by |
1067 | You can chose to use a pure-perl implementation by loading the |
192 | loading the "AnyEvent::Impl::Perl" module, but letting AnyEvent chose is |
1068 | "AnyEvent::Loop" module, which gives you similar behaviour everywhere, |
193 | generally better. |
1069 | but letting AnyEvent chose the model is generally better. |
|
|
1070 | |
|
|
1071 | MAINLOOP EMULATION |
|
|
1072 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
1073 | only want to use AnyEvent), you do not want to run a specific event |
|
|
1074 | loop. |
|
|
1075 | |
|
|
1076 | In that case, you can use a condition variable like this: |
|
|
1077 | |
|
|
1078 | AnyEvent->condvar->recv; |
|
|
1079 | |
|
|
1080 | This has the effect of entering the event loop and looping forever. |
|
|
1081 | |
|
|
1082 | Note that usually your program has some exit condition, in which case it |
|
|
1083 | is better to use the "traditional" approach of storing a condition |
|
|
1084 | variable somewhere, waiting for it, and sending it when the program |
|
|
1085 | should exit cleanly. |
|
|
1086 | |
|
|
1087 | OTHER MODULES |
|
|
1088 | The following is a non-exhaustive list of additional modules that use |
|
|
1089 | AnyEvent as a client and can therefore be mixed easily with other |
|
|
1090 | AnyEvent modules and other event loops in the same program. Some of the |
|
|
1091 | modules come as part of AnyEvent, the others are available via CPAN (see |
|
|
1092 | <http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for a longer |
|
|
1093 | non-exhaustive list), and the list is heavily biased towards modules of |
|
|
1094 | the AnyEvent author himself :) |
|
|
1095 | |
|
|
1096 | AnyEvent::Util (part of the AnyEvent distribution) |
|
|
1097 | Contains various utility functions that replace often-used blocking |
|
|
1098 | functions such as "inet_aton" with event/callback-based versions. |
|
|
1099 | |
|
|
1100 | AnyEvent::Socket (part of the AnyEvent distribution) |
|
|
1101 | Provides various utility functions for (internet protocol) sockets, |
|
|
1102 | addresses and name resolution. Also functions to create non-blocking |
|
|
1103 | tcp connections or tcp servers, with IPv6 and SRV record support and |
|
|
1104 | more. |
|
|
1105 | |
|
|
1106 | AnyEvent::Handle (part of the AnyEvent distribution) |
|
|
1107 | Provide read and write buffers, manages watchers for reads and |
|
|
1108 | writes, supports raw and formatted I/O, I/O queued and fully |
|
|
1109 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS). |
|
|
1110 | |
|
|
1111 | AnyEvent::DNS (part of the AnyEvent distribution) |
|
|
1112 | Provides rich asynchronous DNS resolver capabilities. |
|
|
1113 | |
|
|
1114 | AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, |
|
|
1115 | AnyEvent::IGS, AnyEvent::FCP |
|
|
1116 | Implement event-based interfaces to the protocols of the same name |
|
|
1117 | (for the curious, IGS is the International Go Server and FCP is the |
|
|
1118 | Freenet Client Protocol). |
|
|
1119 | |
|
|
1120 | AnyEvent::AIO (part of the AnyEvent distribution) |
|
|
1121 | Truly asynchronous (as opposed to non-blocking) I/O, should be in |
|
|
1122 | the toolbox of every event programmer. AnyEvent::AIO transparently |
|
|
1123 | fuses IO::AIO and AnyEvent together, giving AnyEvent access to |
|
|
1124 | event-based file I/O, and much more. |
|
|
1125 | |
|
|
1126 | AnyEvent::Filesys::Notify |
|
|
1127 | AnyEvent is good for non-blocking stuff, but it can't detect file or |
|
|
1128 | path changes (e.g. "watch this directory for new files", "watch this |
|
|
1129 | file for changes"). The AnyEvent::Filesys::Notify module promises to |
|
|
1130 | do just that in a portbale fashion, supporting inotify on GNU/Linux |
|
|
1131 | and some weird, without doubt broken, stuff on OS X to monitor |
|
|
1132 | files. It can fall back to blocking scans at regular intervals |
|
|
1133 | transparently on other platforms, so it's about as portable as it |
|
|
1134 | gets. |
|
|
1135 | |
|
|
1136 | (I haven't used it myself, but I haven't heard anybody complaining |
|
|
1137 | about it yet). |
|
|
1138 | |
|
|
1139 | AnyEvent::DBI |
|
|
1140 | Executes DBI requests asynchronously in a proxy process for you, |
|
|
1141 | notifying you in an event-based way when the operation is finished. |
|
|
1142 | |
|
|
1143 | AnyEvent::HTTPD |
|
|
1144 | A simple embedded webserver. |
|
|
1145 | |
|
|
1146 | AnyEvent::FastPing |
|
|
1147 | The fastest ping in the west. |
|
|
1148 | |
|
|
1149 | Coro |
|
|
1150 | Has special support for AnyEvent via Coro::AnyEvent, which allows |
|
|
1151 | you to simply invert the flow control - don't call us, we will call |
|
|
1152 | you: |
|
|
1153 | |
|
|
1154 | async { |
|
|
1155 | Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it |
|
|
1156 | print "5 seconds later!\n"; |
|
|
1157 | |
|
|
1158 | Coro::AnyEvent::readable *STDIN; # uses an I/O watcher |
|
|
1159 | my $line = <STDIN>; # works for ttys |
|
|
1160 | |
|
|
1161 | AnyEvent::HTTP::http_get "url", Coro::rouse_cb; |
|
|
1162 | my ($body, $hdr) = Coro::rouse_wait; |
|
|
1163 | }; |
|
|
1164 | |
|
|
1165 | SIMPLIFIED AE API |
|
|
1166 | Starting with version 5.0, AnyEvent officially supports a second, much |
|
|
1167 | simpler, API that is designed to reduce the calling, typing and memory |
|
|
1168 | overhead by using function call syntax and a fixed number of parameters. |
|
|
1169 | |
|
|
1170 | See the AE manpage for details. |
|
|
1171 | |
|
|
1172 | ERROR AND EXCEPTION HANDLING |
|
|
1173 | In general, AnyEvent does not do any error handling - it relies on the |
|
|
1174 | caller to do that if required. The AnyEvent::Strict module (see also the |
|
|
1175 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
|
|
1176 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
1177 | development. |
|
|
1178 | |
|
|
1179 | As for exception handling (i.e. runtime errors and exceptions thrown |
|
|
1180 | while executing a callback), this is not only highly event-loop |
|
|
1181 | specific, but also not in any way wrapped by this module, as this is the |
|
|
1182 | job of the main program. |
|
|
1183 | |
|
|
1184 | The pure perl event loop simply re-throws the exception (usually within |
|
|
1185 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
|
|
1186 | Glib uses "install_exception_handler" and so on. |
|
|
1187 | |
|
|
1188 | ENVIRONMENT VARIABLES |
|
|
1189 | AnyEvent supports a number of environment variables that tune the |
|
|
1190 | runtime behaviour. They are usually evaluated when AnyEvent is loaded, |
|
|
1191 | initialised, or a submodule that uses them is loaded. Many of them also |
|
|
1192 | cause AnyEvent to load additional modules - for example, |
|
|
1193 | "PERL_ANYEVENT_DEBUG_WRAP" causes the AnyEvent::Debug module to be |
|
|
1194 | loaded. |
|
|
1195 | |
|
|
1196 | All the environment variables documented here start with |
|
|
1197 | "PERL_ANYEVENT_", which is what AnyEvent considers its own namespace. |
|
|
1198 | Other modules are encouraged (but by no means required) to use |
|
|
1199 | "PERL_ANYEVENT_SUBMODULE" if they have registered the |
|
|
1200 | AnyEvent::Submodule namespace on CPAN, for any submodule. For example, |
|
|
1201 | AnyEvent::HTTP could be expected to use "PERL_ANYEVENT_HTTP_PROXY" (it |
|
|
1202 | should not access env variables starting with "AE_", see below). |
|
|
1203 | |
|
|
1204 | All variables can also be set via the "AE_" prefix, that is, instead of |
|
|
1205 | setting "PERL_ANYEVENT_VERBOSE" you can also set "AE_VERBOSE". In case |
|
|
1206 | there is a clash btween anyevent and another program that uses |
|
|
1207 | "AE_something" you can set the corresponding "PERL_ANYEVENT_something" |
|
|
1208 | variable to the empty string, as those variables take precedence. |
|
|
1209 | |
|
|
1210 | When AnyEvent is first loaded, it copies all "AE_xxx" env variables to |
|
|
1211 | their "PERL_ANYEVENT_xxx" counterpart unless that variable already |
|
|
1212 | exists. If taint mode is on, then AnyEvent will remove *all* environment |
|
|
1213 | variables starting with "PERL_ANYEVENT_" from %ENV (or replace them with |
|
|
1214 | "undef" or the empty string, if the corresaponding "AE_" variable is |
|
|
1215 | set). |
|
|
1216 | |
|
|
1217 | The exact algorithm is currently: |
|
|
1218 | |
|
|
1219 | 1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV |
|
|
1220 | 2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists |
|
|
1221 | 3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef. |
|
|
1222 | |
|
|
1223 | This ensures that child processes will not see the "AE_" variables. |
|
|
1224 | |
|
|
1225 | The following environment variables are currently known to AnyEvent: |
|
|
1226 | |
|
|
1227 | "PERL_ANYEVENT_VERBOSE" |
|
|
1228 | By default, AnyEvent will log messages with loglevel 4 ("error") or |
|
|
1229 | higher (see AnyEvent::Log). You can set this environment variable to |
|
|
1230 | a numerical loglevel to make AnyEvent more (or less) talkative. |
|
|
1231 | |
|
|
1232 | If you want to do more than just set the global logging level you |
|
|
1233 | should have a look at "PERL_ANYEVENT_LOG", which allows much more |
|
|
1234 | complex specifications. |
|
|
1235 | |
|
|
1236 | When set to 0 ("off"), then no messages whatsoever will be logged |
|
|
1237 | with everything else at defaults. |
|
|
1238 | |
|
|
1239 | When set to 5 or higher ("warn"), AnyEvent warns about unexpected |
|
|
1240 | conditions, such as not being able to load the event model specified |
|
|
1241 | by "PERL_ANYEVENT_MODEL", or a guard callback throwing an exception |
|
|
1242 | - this is the minimum recommended level for use during development. |
|
|
1243 | |
|
|
1244 | When set to 7 or higher (info), AnyEvent reports which event model |
|
|
1245 | it chooses. |
|
|
1246 | |
|
|
1247 | When set to 8 or higher (debug), then AnyEvent will report extra |
|
|
1248 | information on which optional modules it loads and how it implements |
|
|
1249 | certain features. |
|
|
1250 | |
|
|
1251 | "PERL_ANYEVENT_LOG" |
|
|
1252 | Accepts rather complex logging specifications. For example, you |
|
|
1253 | could log all "debug" messages of some module to stderr, warnings |
|
|
1254 | and above to stderr, and errors and above to syslog, with: |
|
|
1255 | |
|
|
1256 | PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog |
|
|
1257 | |
|
|
1258 | For the rather extensive details, see AnyEvent::Log. |
|
|
1259 | |
|
|
1260 | This variable is evaluated when AnyEvent (or AnyEvent::Log) is |
|
|
1261 | loaded, so will take effect even before AnyEvent has initialised |
|
|
1262 | itself. |
|
|
1263 | |
|
|
1264 | Note that specifying this environment variable causes the |
|
|
1265 | AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE" |
|
|
1266 | does not, so only using the latter saves a few hundred kB of memory |
|
|
1267 | unless a module explicitly needs the extra features of |
|
|
1268 | AnyEvent::Log. |
|
|
1269 | |
|
|
1270 | "PERL_ANYEVENT_STRICT" |
|
|
1271 | AnyEvent does not do much argument checking by default, as thorough |
|
|
1272 | argument checking is very costly. Setting this variable to a true |
|
|
1273 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
|
|
1274 | thoroughly check the arguments passed to most method calls. If it |
|
|
1275 | finds any problems, it will croak. |
|
|
1276 | |
|
|
1277 | In other words, enables "strict" mode. |
|
|
1278 | |
|
|
1279 | Unlike "use strict" (or its modern cousin, "use common::sense", it |
|
|
1280 | is definitely recommended to keep it off in production. Keeping |
|
|
1281 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
|
|
1282 | programs can be very useful, however. |
|
|
1283 | |
|
|
1284 | "PERL_ANYEVENT_DEBUG_SHELL" |
|
|
1285 | If this env variable is nonempty, then its contents will be |
|
|
1286 | interpreted by "AnyEvent::Socket::parse_hostport" and |
|
|
1287 | "AnyEvent::Debug::shell" (after replacing every occurance of $$ by |
|
|
1288 | the process pid). The shell object is saved in |
|
|
1289 | $AnyEvent::Debug::SHELL. |
|
|
1290 | |
|
|
1291 | This happens when the first watcher is created. |
|
|
1292 | |
|
|
1293 | For example, to bind a debug shell on a unix domain socket in |
|
|
1294 | /tmp/debug<pid>.sock, you could use this: |
|
|
1295 | |
|
|
1296 | PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog |
|
|
1297 | # connect with e.g.: socat readline /tmp/debug123.sock |
|
|
1298 | |
|
|
1299 | Or to bind to tcp port 4545 on localhost: |
|
|
1300 | |
|
|
1301 | PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog |
|
|
1302 | # connect with e.g.: telnet localhost 4545 |
|
|
1303 | |
|
|
1304 | Note that creating sockets in /tmp or on localhost is very unsafe on |
|
|
1305 | multiuser systems. |
|
|
1306 | |
|
|
1307 | "PERL_ANYEVENT_DEBUG_WRAP" |
|
|
1308 | Can be set to 0, 1 or 2 and enables wrapping of all watchers for |
|
|
1309 | debugging purposes. See "AnyEvent::Debug::wrap" for details. |
|
|
1310 | |
|
|
1311 | "PERL_ANYEVENT_MODEL" |
|
|
1312 | This can be used to specify the event model to be used by AnyEvent, |
|
|
1313 | before auto detection and -probing kicks in. |
|
|
1314 | |
|
|
1315 | It normally is a string consisting entirely of ASCII letters (e.g. |
|
|
1316 | "EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and |
|
|
1317 | the resulting module name is loaded and - if the load was successful |
|
|
1318 | - used as event model backend. If it fails to load then AnyEvent |
|
|
1319 | will proceed with auto detection and -probing. |
|
|
1320 | |
|
|
1321 | If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::") |
|
|
1322 | then nothing gets prepended and the module name is used as-is (hint: |
|
|
1323 | "::" at the end of a string designates a module name and quotes it |
|
|
1324 | appropriately). |
|
|
1325 | |
|
|
1326 | For example, to force the pure perl model (AnyEvent::Loop::Perl) you |
|
|
1327 | could start your program like this: |
|
|
1328 | |
|
|
1329 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1330 | |
|
|
1331 | "PERL_ANYEVENT_IO_MODEL" |
|
|
1332 | The current file I/O model - see AnyEvent::IO for more info. |
|
|
1333 | |
|
|
1334 | At the moment, only "Perl" (small, pure-perl, synchronous) and |
|
|
1335 | "IOAIO" (truly asynchronous) are supported. The default is "IOAIO" |
|
|
1336 | if AnyEvent::AIO can be loaded, otherwise it is "Perl". |
|
|
1337 | |
|
|
1338 | "PERL_ANYEVENT_PROTOCOLS" |
|
|
1339 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
|
|
1340 | preferences for IPv4 or IPv6. The default is unspecified (and might |
|
|
1341 | change, or be the result of auto probing). |
|
|
1342 | |
|
|
1343 | Must be set to a comma-separated list of protocols or address |
|
|
1344 | families, current supported: "ipv4" and "ipv6". Only protocols |
|
|
1345 | mentioned will be used, and preference will be given to protocols |
|
|
1346 | mentioned earlier in the list. |
|
|
1347 | |
|
|
1348 | This variable can effectively be used for denial-of-service attacks |
|
|
1349 | against local programs (e.g. when setuid), although the impact is |
|
|
1350 | likely small, as the program has to handle conenction and other |
|
|
1351 | failures anyways. |
|
|
1352 | |
|
|
1353 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
|
|
1354 | IPv6, but support both and try to use both. |
|
|
1355 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
|
|
1356 | resolve or contact IPv6 addresses. |
|
|
1357 | "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but |
|
|
1358 | prefer IPv6 over IPv4. |
|
|
1359 | |
|
|
1360 | "PERL_ANYEVENT_HOSTS" |
|
|
1361 | This variable, if specified, overrides the /etc/hosts file used by |
|
|
1362 | AnyEvent::Socket"::resolve_sockaddr", i.e. hosts aliases will be |
|
|
1363 | read from that file instead. |
|
|
1364 | |
|
|
1365 | "PERL_ANYEVENT_EDNS0" |
|
|
1366 | Used by AnyEvent::DNS to decide whether to use the EDNS0 extension |
|
|
1367 | for DNS. This extension is generally useful to reduce DNS traffic, |
|
|
1368 | especially when DNSSEC is involved, but some (broken) firewalls drop |
|
|
1369 | such DNS packets, which is why it is off by default. |
|
|
1370 | |
|
|
1371 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
|
|
1372 | EDNS0 in its DNS requests. |
|
|
1373 | |
|
|
1374 | "PERL_ANYEVENT_MAX_FORKS" |
|
|
1375 | The maximum number of child processes that |
|
|
1376 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
1377 | |
|
|
1378 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
|
|
1379 | The default value for the "max_outstanding" parameter for the |
|
|
1380 | default DNS resolver - this is the maximum number of parallel DNS |
|
|
1381 | requests that are sent to the DNS server. |
|
|
1382 | |
|
|
1383 | "PERL_ANYEVENT_MAX_SIGNAL_LATENCY" |
|
|
1384 | Perl has inherently racy signal handling (you can basically choose |
|
|
1385 | between losing signals and memory corruption) - pure perl event |
|
|
1386 | loops (including "AnyEvent::Loop", when "Async::Interrupt" isn't |
|
|
1387 | available) therefore have to poll regularly to avoid losing signals. |
|
|
1388 | |
|
|
1389 | Some event loops are racy, but don't poll regularly, and some event |
|
|
1390 | loops are written in C but are still racy. For those event loops, |
|
|
1391 | AnyEvent installs a timer that regularly wakes up the event loop. |
|
|
1392 | |
|
|
1393 | By default, the interval for this timer is 10 seconds, but you can |
|
|
1394 | override this delay with this environment variable (or by setting |
|
|
1395 | the $AnyEvent::MAX_SIGNAL_LATENCY variable before creating signal |
|
|
1396 | watchers). |
|
|
1397 | |
|
|
1398 | Lower values increase CPU (and energy) usage, higher values can |
|
|
1399 | introduce long delays when reaping children or waiting for signals. |
|
|
1400 | |
|
|
1401 | The AnyEvent::Async module, if available, will be used to avoid this |
|
|
1402 | polling (with most event loops). |
|
|
1403 | |
|
|
1404 | "PERL_ANYEVENT_RESOLV_CONF" |
|
|
1405 | The absolute path to a resolv.conf-style file to use instead of |
|
|
1406 | /etc/resolv.conf (or the OS-specific configuration) in the default |
|
|
1407 | resolver, or the empty string to select the default configuration. |
|
|
1408 | |
|
|
1409 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
|
|
1410 | When neither "ca_file" nor "ca_path" was specified during |
|
|
1411 | AnyEvent::TLS context creation, and either of these environment |
|
|
1412 | variables are nonempty, they will be used to specify CA certificate |
|
|
1413 | locations instead of a system-dependent default. |
|
|
1414 | |
|
|
1415 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
|
|
1416 | When these are set to 1, then the respective modules are not loaded. |
|
|
1417 | Mostly good for testing AnyEvent itself. |
194 | |
1418 | |
195 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1419 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1420 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
1421 | in a module. This section is only of use to event loop authors who want |
|
|
1422 | to provide AnyEvent compatibility. |
|
|
1423 | |
196 | If you need to support another event library which isn't directly |
1424 | If you need to support another event library which isn't directly |
197 | supported by AnyEvent, you can supply your own interface to it by |
1425 | supported by AnyEvent, you can supply your own interface to it by |
198 | pushing, before the first watcher gets created, the package name of the |
1426 | pushing, before the first watcher gets created, the package name of the |
199 | event module and the package name of the interface to use onto |
1427 | event module and the package name of the interface to use onto |
200 | @AnyEvent::REGISTRY. You can do that before and even without loading |
1428 | @AnyEvent::REGISTRY. You can do that before and even without loading |
201 | AnyEvent. |
1429 | AnyEvent, so it is reasonably cheap. |
202 | |
1430 | |
203 | Example: |
1431 | Example: |
204 | |
1432 | |
205 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
1433 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
206 | |
1434 | |
207 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
1435 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
208 | package/class when it finds the "urxvt" package/module is loaded. When |
1436 | package/class when it finds the "urxvt" package/module is already |
|
|
1437 | loaded. |
|
|
1438 | |
209 | AnyEvent is loaded and asked to find a suitable event model, it will |
1439 | When AnyEvent is loaded and asked to find a suitable event model, it |
210 | first check for the presence of urxvt. |
1440 | will first check for the presence of urxvt by trying to "use" the |
|
|
1441 | "urxvt::anyevent" module. |
211 | |
1442 | |
212 | The class should prove implementations for all watcher types (see |
1443 | The class should provide implementations for all watcher types. See |
213 | AnyEvent::Impl::Event (source code), AnyEvent::Impl::Glib (Source code) |
1444 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
214 | and so on for actual examples, use "perldoc -m AnyEvent::Impl::Glib" to |
1445 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
215 | see the sources). |
1446 | the sources. |
216 | |
1447 | |
|
|
1448 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
1449 | provide suitable (hopefully) replacements. |
|
|
1450 | |
217 | The above isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) uses the |
1451 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
218 | above line as-is. An interface isn't included in AnyEvent because it |
1452 | terminal emulator uses the above line as-is. An interface isn't included |
219 | doesn't make sense outside the embedded interpreter inside |
1453 | in AnyEvent because it doesn't make sense outside the embedded |
220 | *rxvt-unicode*, and it is updated and maintained as part of the |
1454 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
221 | *rxvt-unicode* distribution. |
1455 | part of the *rxvt-unicode* distribution. |
222 | |
1456 | |
223 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
1457 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
224 | condition variables: code blocking while waiting for a condition will |
1458 | condition variables: code blocking while waiting for a condition will |
225 | "die". This still works with most modules/usages, and blocking calls |
1459 | "die". This still works with most modules/usages, and blocking calls |
226 | must not be in an interactive appliation, so it makes sense. |
1460 | must not be done in an interactive application, so it makes sense. |
227 | |
1461 | |
228 | ENVIRONMENT VARIABLES |
1462 | EXAMPLE PROGRAM |
229 | The following environment variables are used by this module: |
|
|
230 | |
|
|
231 | "PERL_ANYEVENT_VERBOSE" when set to 2 or higher, reports which event |
|
|
232 | model gets used. |
|
|
233 | |
|
|
234 | EXAMPLE |
|
|
235 | The following program uses an io watcher to read data from stdin, a |
1463 | The following program uses an I/O watcher to read data from STDIN, a |
236 | timer to display a message once per second, and a condvar to exit the |
1464 | timer to display a message once per second, and a condition variable to |
237 | program when the user enters quit: |
1465 | quit the program when the user enters quit: |
238 | |
1466 | |
239 | use AnyEvent; |
1467 | use AnyEvent; |
240 | |
1468 | |
241 | my $cv = AnyEvent->condvar; |
1469 | my $cv = AnyEvent->condvar; |
242 | |
1470 | |
243 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
1471 | my $io_watcher = AnyEvent->io ( |
|
|
1472 | fh => \*STDIN, |
|
|
1473 | poll => 'r', |
|
|
1474 | cb => sub { |
244 | warn "io event <$_[0]>\n"; # will always output <r> |
1475 | warn "io event <$_[0]>\n"; # will always output <r> |
245 | chomp (my $input = <STDIN>); # read a line |
1476 | chomp (my $input = <STDIN>); # read a line |
246 | warn "read: $input\n"; # output what has been read |
1477 | warn "read: $input\n"; # output what has been read |
247 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1478 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
|
|
1479 | }, |
|
|
1480 | ); |
|
|
1481 | |
|
|
1482 | my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub { |
|
|
1483 | warn "timeout\n"; # print 'timeout' at most every second |
248 | }); |
1484 | }); |
249 | |
1485 | |
250 | my $time_watcher; # can only be used once |
|
|
251 | |
|
|
252 | sub new_timer { |
|
|
253 | $timer = AnyEvent->timer (after => 1, cb => sub { |
|
|
254 | warn "timeout\n"; # print 'timeout' about every second |
|
|
255 | &new_timer; # and restart the time |
|
|
256 | }); |
|
|
257 | } |
|
|
258 | |
|
|
259 | new_timer; # create first timer |
|
|
260 | |
|
|
261 | $cv->wait; # wait until user enters /^q/i |
1486 | $cv->recv; # wait until user enters /^q/i |
262 | |
1487 | |
263 | REAL-WORLD EXAMPLE |
1488 | REAL-WORLD EXAMPLE |
264 | Consider the Net::FCP module. It features (among others) the following |
1489 | Consider the Net::FCP module. It features (among others) the following |
265 | API calls, which are to freenet what HTTP GET requests are to http: |
1490 | API calls, which are to freenet what HTTP GET requests are to http: |
266 | |
1491 | |
… | |
… | |
315 | syswrite $txn->{fh}, $txn->{request} |
1540 | syswrite $txn->{fh}, $txn->{request} |
316 | or die "connection or write error"; |
1541 | or die "connection or write error"; |
317 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1542 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
318 | |
1543 | |
319 | Again, "fh_ready_r" waits till all data has arrived, and then stores the |
1544 | Again, "fh_ready_r" waits till all data has arrived, and then stores the |
320 | result and signals any possible waiters that the request ahs finished: |
1545 | result and signals any possible waiters that the request has finished: |
321 | |
1546 | |
322 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1547 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
323 | |
1548 | |
324 | if (end-of-file or data complete) { |
1549 | if (end-of-file or data complete) { |
325 | $txn->{result} = $txn->{buf}; |
1550 | $txn->{result} = $txn->{buf}; |
326 | $txn->{finished}->broadcast; |
1551 | $txn->{finished}->send; |
327 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1552 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
328 | } |
1553 | } |
329 | |
1554 | |
330 | The "result" method, finally, just waits for the finished signal (if the |
1555 | The "result" method, finally, just waits for the finished signal (if the |
331 | request was already finished, it doesn't wait, of course, and returns |
1556 | request was already finished, it doesn't wait, of course, and returns |
332 | the data: |
1557 | the data: |
333 | |
1558 | |
334 | $txn->{finished}->wait; |
1559 | $txn->{finished}->recv; |
335 | return $txn->{result}; |
1560 | return $txn->{result}; |
336 | |
1561 | |
337 | The actual code goes further and collects all errors ("die"s, |
1562 | The actual code goes further and collects all errors ("die"s, |
338 | exceptions) that occured during request processing. The "result" method |
1563 | exceptions) that occurred during request processing. The "result" method |
339 | detects wether an exception as thrown (it is stored inside the $txn |
1564 | detects whether an exception as thrown (it is stored inside the $txn |
340 | object) and just throws the exception, which means connection errors and |
1565 | object) and just throws the exception, which means connection errors and |
341 | other problems get reported tot he code that tries to use the result, |
1566 | other problems get reported to the code that tries to use the result, |
342 | not in a random callback. |
1567 | not in a random callback. |
343 | |
1568 | |
344 | All of this enables the following usage styles: |
1569 | All of this enables the following usage styles: |
345 | |
1570 | |
346 | 1. Blocking: |
1571 | 1. Blocking: |
347 | |
1572 | |
348 | my $data = $fcp->client_get ($url); |
1573 | my $data = $fcp->client_get ($url); |
349 | |
1574 | |
350 | 2. Blocking, but parallelizing: |
1575 | 2. Blocking, but running in parallel: |
351 | |
1576 | |
352 | my @datas = map $_->result, |
1577 | my @datas = map $_->result, |
353 | map $fcp->txn_client_get ($_), |
1578 | map $fcp->txn_client_get ($_), |
354 | @urls; |
1579 | @urls; |
355 | |
1580 | |
356 | Both blocking examples work without the module user having to know |
1581 | Both blocking examples work without the module user having to know |
357 | anything about events. |
1582 | anything about events. |
358 | |
1583 | |
359 | 3a. Event-based in a main program, using any support Event module: |
1584 | 3a. Event-based in a main program, using any supported event module: |
360 | |
1585 | |
361 | use Event; |
1586 | use EV; |
362 | |
1587 | |
363 | $fcp->txn_client_get ($url)->cb (sub { |
1588 | $fcp->txn_client_get ($url)->cb (sub { |
364 | my $txn = shift; |
1589 | my $txn = shift; |
365 | my $data = $txn->result; |
1590 | my $data = $txn->result; |
366 | ... |
1591 | ... |
367 | }); |
1592 | }); |
368 | |
1593 | |
369 | Event::loop; |
1594 | EV::loop; |
370 | |
1595 | |
371 | 3b. The module user could use AnyEvent, too: |
1596 | 3b. The module user could use AnyEvent, too: |
372 | |
1597 | |
373 | use AnyEvent; |
1598 | use AnyEvent; |
374 | |
1599 | |
375 | my $quit = AnyEvent->condvar; |
1600 | my $quit = AnyEvent->condvar; |
376 | |
1601 | |
377 | $fcp->txn_client_get ($url)->cb (sub { |
1602 | $fcp->txn_client_get ($url)->cb (sub { |
378 | ... |
1603 | ... |
379 | $quit->broadcast; |
1604 | $quit->send; |
380 | }); |
1605 | }); |
381 | |
1606 | |
382 | $quit->wait; |
1607 | $quit->recv; |
|
|
1608 | |
|
|
1609 | BENCHMARKS |
|
|
1610 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1611 | over the event loops themselves and to give you an impression of the |
|
|
1612 | speed of various event loops I prepared some benchmarks. |
|
|
1613 | |
|
|
1614 | BENCHMARKING ANYEVENT OVERHEAD |
|
|
1615 | Here is a benchmark of various supported event models used natively and |
|
|
1616 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1617 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1618 | which it is), lets them fire exactly once and destroys them again. |
|
|
1619 | |
|
|
1620 | Source code for this benchmark is found as eg/bench in the AnyEvent |
|
|
1621 | distribution. It uses the AE interface, which makes a real difference |
|
|
1622 | for the EV and Perl backends only. |
|
|
1623 | |
|
|
1624 | Explanation of the columns |
|
|
1625 | *watcher* is the number of event watchers created/destroyed. Since |
|
|
1626 | different event models feature vastly different performances, each event |
|
|
1627 | loop was given a number of watchers so that overall runtime is |
|
|
1628 | acceptable and similar between tested event loop (and keep them from |
|
|
1629 | crashing): Glib would probably take thousands of years if asked to |
|
|
1630 | process the same number of watchers as EV in this benchmark. |
|
|
1631 | |
|
|
1632 | *bytes* is the number of bytes (as measured by the resident set size, |
|
|
1633 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1634 | and Perl-based overheads. |
|
|
1635 | |
|
|
1636 | *create* is the time, in microseconds (millionths of seconds), that it |
|
|
1637 | takes to create a single watcher. The callback is a closure shared |
|
|
1638 | between all watchers, to avoid adding memory overhead. That means |
|
|
1639 | closure creation and memory usage is not included in the figures. |
|
|
1640 | |
|
|
1641 | *invoke* is the time, in microseconds, used to invoke a simple callback. |
|
|
1642 | The callback simply counts down a Perl variable and after it was invoked |
|
|
1643 | "watcher" times, it would "->send" a condvar once to signal the end of |
|
|
1644 | this phase. |
|
|
1645 | |
|
|
1646 | *destroy* is the time, in microseconds, that it takes to destroy a |
|
|
1647 | single watcher. |
|
|
1648 | |
|
|
1649 | Results |
|
|
1650 | name watchers bytes create invoke destroy comment |
|
|
1651 | EV/EV 100000 223 0.47 0.43 0.27 EV native interface |
|
|
1652 | EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers |
|
|
1653 | Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal |
|
|
1654 | Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation |
|
|
1655 | Event/Event 16000 516 31.16 31.84 0.82 Event native interface |
|
|
1656 | Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers |
|
|
1657 | IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll |
|
|
1658 | IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll |
|
|
1659 | Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour |
|
|
1660 | Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers |
|
|
1661 | POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event |
|
|
1662 | POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select |
|
|
1663 | |
|
|
1664 | Discussion |
|
|
1665 | The benchmark does *not* measure scalability of the event loop very |
|
|
1666 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1667 | can never compete with an event loop that uses epoll when the number of |
|
|
1668 | file descriptors grows high. In this benchmark, all events become ready |
|
|
1669 | at the same time, so select/poll-based implementations get an unnatural |
|
|
1670 | speed boost. |
|
|
1671 | |
|
|
1672 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1673 | overall speed, that is, creating twice as many watchers doesn't take |
|
|
1674 | twice the time - usually it takes longer. This puts event loops tested |
|
|
1675 | with a higher number of watchers at a disadvantage. |
|
|
1676 | |
|
|
1677 | To put the range of results into perspective, consider that on the |
|
|
1678 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1679 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
|
|
1680 | CPU cycles with POE. |
|
|
1681 | |
|
|
1682 | "EV" is the sole leader regarding speed and memory use, which are both |
|
|
1683 | maximal/minimal, respectively. When using the AE API there is zero |
|
|
1684 | overhead (when going through the AnyEvent API create is about 5-6 times |
|
|
1685 | slower, with other times being equal, so still uses far less memory than |
|
|
1686 | any other event loop and is still faster than Event natively). |
|
|
1687 | |
|
|
1688 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1689 | constant timeout and the use of a single fd hit optimisations in the |
|
|
1690 | perl interpreter and the backend itself). Nevertheless this shows that |
|
|
1691 | it adds very little overhead in itself. Like any select-based backend |
|
|
1692 | its performance becomes really bad with lots of file descriptors (and |
|
|
1693 | few of them active), of course, but this was not subject of this |
|
|
1694 | benchmark. |
|
|
1695 | |
|
|
1696 | The "Event" module has a relatively high setup and callback invocation |
|
|
1697 | cost, but overall scores in on the third place. |
|
|
1698 | |
|
|
1699 | "IO::Async" performs admirably well, about on par with "Event", even |
|
|
1700 | when using its pure perl backend. |
|
|
1701 | |
|
|
1702 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
|
|
1703 | callback invocation and overall ends up in the same class as "Event". |
|
|
1704 | However, Glib scales extremely badly, doubling the number of watchers |
|
|
1705 | increases the processing time by more than a factor of four, making it |
|
|
1706 | completely unusable when using larger numbers of watchers (note that |
|
|
1707 | only a single file descriptor was used in the benchmark, so |
|
|
1708 | inefficiencies of "poll" do not account for this). |
|
|
1709 | |
|
|
1710 | The "Tk" adaptor works relatively well. The fact that it crashes with |
|
|
1711 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1712 | precedence over speed. Nevertheless, its performance is surprising, as |
|
|
1713 | the file descriptor is dup()ed for each watcher. This shows that the |
|
|
1714 | dup() employed by some adaptors is not a big performance issue (it does |
|
|
1715 | incur a hidden memory cost inside the kernel which is not reflected in |
|
|
1716 | the figures above). |
|
|
1717 | |
|
|
1718 | "POE", regardless of underlying event loop (whether using its pure perl |
|
|
1719 | select-based backend or the Event module, the POE-EV backend couldn't be |
|
|
1720 | tested because it wasn't working) shows abysmal performance and memory |
|
|
1721 | usage with AnyEvent: Watchers use almost 30 times as much memory as EV |
|
|
1722 | watchers, and 10 times as much memory as Event (the high memory |
|
|
1723 | requirements are caused by requiring a session for each watcher). |
|
|
1724 | Watcher invocation speed is almost 900 times slower than with AnyEvent's |
|
|
1725 | pure perl implementation. |
|
|
1726 | |
|
|
1727 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1728 | for the performance issues, though, as session creation overhead is |
|
|
1729 | small compared to execution of the state machine, which is coded pretty |
|
|
1730 | optimally within AnyEvent::Impl::POE (and while everybody agrees that |
|
|
1731 | using multiple sessions is not a good approach, especially regarding |
|
|
1732 | memory usage, even the author of POE could not come up with a faster |
|
|
1733 | design). |
|
|
1734 | |
|
|
1735 | Summary |
|
|
1736 | * Using EV through AnyEvent is faster than any other event loop (even |
|
|
1737 | when used without AnyEvent), but most event loops have acceptable |
|
|
1738 | performance with or without AnyEvent. |
|
|
1739 | |
|
|
1740 | * The overhead AnyEvent adds is usually much smaller than the overhead |
|
|
1741 | of the actual event loop, only with extremely fast event loops such |
|
|
1742 | as EV does AnyEvent add significant overhead. |
|
|
1743 | |
|
|
1744 | * You should avoid POE like the plague if you want performance or |
|
|
1745 | reasonable memory usage. |
|
|
1746 | |
|
|
1747 | BENCHMARKING THE LARGE SERVER CASE |
|
|
1748 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1749 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1750 | timeout watcher that gets reset on activity (but never fires), and an |
|
|
1751 | I/O watcher waiting for input on one side of the socket. Each time the |
|
|
1752 | socket watcher reads a byte it will write that byte to a random other |
|
|
1753 | "server". |
|
|
1754 | |
|
|
1755 | The effect is that there will be a lot of I/O watchers, only part of |
|
|
1756 | which are active at any one point (so there is a constant number of |
|
|
1757 | active fds for each loop iteration, but which fds these are is random). |
|
|
1758 | The timeout is reset each time something is read because that reflects |
|
|
1759 | how most timeouts work (and puts extra pressure on the event loops). |
|
|
1760 | |
|
|
1761 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
|
|
1762 | 100 (1%) are active. This mirrors the activity of large servers with |
|
|
1763 | many connections, most of which are idle at any one point in time. |
|
|
1764 | |
|
|
1765 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
|
|
1766 | distribution. It uses the AE interface, which makes a real difference |
|
|
1767 | for the EV and Perl backends only. |
|
|
1768 | |
|
|
1769 | Explanation of the columns |
|
|
1770 | *sockets* is the number of sockets, and twice the number of "servers" |
|
|
1771 | (as each server has a read and write socket end). |
|
|
1772 | |
|
|
1773 | *create* is the time it takes to create a socket pair (which is |
|
|
1774 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1775 | |
|
|
1776 | *request*, the most important value, is the time it takes to handle a |
|
|
1777 | single "request", that is, reading the token from the pipe and |
|
|
1778 | forwarding it to another server. This includes deleting the old timeout |
|
|
1779 | and creating a new one that moves the timeout into the future. |
|
|
1780 | |
|
|
1781 | Results |
|
|
1782 | name sockets create request |
|
|
1783 | EV 20000 62.66 7.99 |
|
|
1784 | Perl 20000 68.32 32.64 |
|
|
1785 | IOAsync 20000 174.06 101.15 epoll |
|
|
1786 | IOAsync 20000 174.67 610.84 poll |
|
|
1787 | Event 20000 202.69 242.91 |
|
|
1788 | Glib 20000 557.01 1689.52 |
|
|
1789 | POE 20000 341.54 12086.32 uses POE::Loop::Event |
|
|
1790 | |
|
|
1791 | Discussion |
|
|
1792 | This benchmark *does* measure scalability and overall performance of the |
|
|
1793 | particular event loop. |
|
|
1794 | |
|
|
1795 | EV is again fastest. Since it is using epoll on my system, the setup |
|
|
1796 | time is relatively high, though. |
|
|
1797 | |
|
|
1798 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1799 | loops Event and Glib. |
|
|
1800 | |
|
|
1801 | IO::Async performs very well when using its epoll backend, and still |
|
|
1802 | quite good compared to Glib when using its pure perl backend. |
|
|
1803 | |
|
|
1804 | Event suffers from high setup time as well (look at its code and you |
|
|
1805 | will understand why). Callback invocation also has a high overhead |
|
|
1806 | compared to the "$_->() for .."-style loop that the Perl event loop |
|
|
1807 | uses. Event uses select or poll in basically all documented |
|
|
1808 | configurations. |
|
|
1809 | |
|
|
1810 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1811 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1812 | |
|
|
1813 | POE is still completely out of the picture, taking over 1000 times as |
|
|
1814 | long as EV, and over 100 times as long as the Perl implementation, even |
|
|
1815 | though it uses a C-based event loop in this case. |
|
|
1816 | |
|
|
1817 | Summary |
|
|
1818 | * The pure perl implementation performs extremely well. |
|
|
1819 | |
|
|
1820 | * Avoid Glib or POE in large projects where performance matters. |
|
|
1821 | |
|
|
1822 | BENCHMARKING SMALL SERVERS |
|
|
1823 | While event loops should scale (and select-based ones do not...) even to |
|
|
1824 | large servers, most programs we (or I :) actually write have only a few |
|
|
1825 | I/O watchers. |
|
|
1826 | |
|
|
1827 | In this benchmark, I use the same benchmark program as in the large |
|
|
1828 | server case, but it uses only eight "servers", of which three are active |
|
|
1829 | at any one time. This should reflect performance for a small server |
|
|
1830 | relatively well. |
|
|
1831 | |
|
|
1832 | The columns are identical to the previous table. |
|
|
1833 | |
|
|
1834 | Results |
|
|
1835 | name sockets create request |
|
|
1836 | EV 16 20.00 6.54 |
|
|
1837 | Perl 16 25.75 12.62 |
|
|
1838 | Event 16 81.27 35.86 |
|
|
1839 | Glib 16 32.63 15.48 |
|
|
1840 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1841 | |
|
|
1842 | Discussion |
|
|
1843 | The benchmark tries to test the performance of a typical small server. |
|
|
1844 | While knowing how various event loops perform is interesting, keep in |
|
|
1845 | mind that their overhead in this case is usually not as important, due |
|
|
1846 | to the small absolute number of watchers (that is, you need efficiency |
|
|
1847 | and speed most when you have lots of watchers, not when you only have a |
|
|
1848 | few of them). |
|
|
1849 | |
|
|
1850 | EV is again fastest. |
|
|
1851 | |
|
|
1852 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1853 | loops Event and Glib, although the difference is too small to really |
|
|
1854 | matter. |
|
|
1855 | |
|
|
1856 | POE also performs much better in this case, but is is still far behind |
|
|
1857 | the others. |
|
|
1858 | |
|
|
1859 | Summary |
|
|
1860 | * C-based event loops perform very well with small number of watchers, |
|
|
1861 | as the management overhead dominates. |
|
|
1862 | |
|
|
1863 | THE IO::Lambda BENCHMARK |
|
|
1864 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
1865 | could be misinterpreted to make AnyEvent look bad. In fact, the |
|
|
1866 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
|
|
1867 | better (which shouldn't come as a surprise to anybody). As such, the |
|
|
1868 | benchmark is fine, and mostly shows that the AnyEvent backend from |
|
|
1869 | IO::Lambda isn't very optimal. But how would AnyEvent compare when used |
|
|
1870 | without the extra baggage? To explore this, I wrote the equivalent |
|
|
1871 | benchmark for AnyEvent. |
|
|
1872 | |
|
|
1873 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
1874 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
1875 | creates the next connection. This is a rather bad benchmark, as it |
|
|
1876 | doesn't test the efficiency of the framework or much non-blocking I/O, |
|
|
1877 | but it is a benchmark nevertheless. |
|
|
1878 | |
|
|
1879 | name runtime |
|
|
1880 | Lambda/select 0.330 sec |
|
|
1881 | + optimized 0.122 sec |
|
|
1882 | Lambda/AnyEvent 0.327 sec |
|
|
1883 | + optimized 0.138 sec |
|
|
1884 | Raw sockets/select 0.077 sec |
|
|
1885 | POE/select, components 0.662 sec |
|
|
1886 | POE/select, raw sockets 0.226 sec |
|
|
1887 | POE/select, optimized 0.404 sec |
|
|
1888 | |
|
|
1889 | AnyEvent/select/nb 0.085 sec |
|
|
1890 | AnyEvent/EV/nb 0.068 sec |
|
|
1891 | +state machine 0.134 sec |
|
|
1892 | |
|
|
1893 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
|
|
1894 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
1895 | defeating the purpose of an event-based solution. All of the newly |
|
|
1896 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
1897 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
1898 | resolver), so AnyEvent is at a disadvantage here, as non-blocking |
|
|
1899 | connects generally require a lot more bookkeeping and event handling |
|
|
1900 | than blocking connects (which involve a single syscall only). |
|
|
1901 | |
|
|
1902 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
|
|
1903 | offers similar expressive power as POE and IO::Lambda, using |
|
|
1904 | conventional Perl syntax. This means that both the echo server and the |
|
|
1905 | client are 100% non-blocking, further placing it at a disadvantage. |
|
|
1906 | |
|
|
1907 | As you can see, the AnyEvent + EV combination even beats the |
|
|
1908 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
|
|
1909 | backend easily beats IO::Lambda and POE. |
|
|
1910 | |
|
|
1911 | And even the 100% non-blocking version written using the high-level (and |
|
|
1912 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda |
|
|
1913 | higher level ("unoptimised") abstractions by a large margin, even though |
|
|
1914 | it does all of DNS, tcp-connect and socket I/O in a non-blocking way. |
|
|
1915 | |
|
|
1916 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
|
|
1917 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
|
|
1918 | part of the IO::Lambda distribution and were used without any changes. |
|
|
1919 | |
|
|
1920 | SIGNALS |
|
|
1921 | AnyEvent currently installs handlers for these signals: |
|
|
1922 | |
|
|
1923 | SIGCHLD |
|
|
1924 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
|
|
1925 | emulation for event loops that do not support them natively. Also, |
|
|
1926 | some event loops install a similar handler. |
|
|
1927 | |
|
|
1928 | Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, |
|
|
1929 | then AnyEvent will reset it to default, to avoid losing child exit |
|
|
1930 | statuses. |
|
|
1931 | |
|
|
1932 | SIGPIPE |
|
|
1933 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
|
|
1934 | "undef" when AnyEvent gets loaded. |
|
|
1935 | |
|
|
1936 | The rationale for this is that AnyEvent users usually do not really |
|
|
1937 | depend on SIGPIPE delivery (which is purely an optimisation for |
|
|
1938 | shell use, or badly-written programs), but "SIGPIPE" can cause |
|
|
1939 | spurious and rare program exits as a lot of people do not expect |
|
|
1940 | "SIGPIPE" when writing to some random socket. |
|
|
1941 | |
|
|
1942 | The rationale for installing a no-op handler as opposed to ignoring |
|
|
1943 | it is that this way, the handler will be restored to defaults on |
|
|
1944 | exec. |
|
|
1945 | |
|
|
1946 | Feel free to install your own handler, or reset it to defaults. |
|
|
1947 | |
|
|
1948 | RECOMMENDED/OPTIONAL MODULES |
|
|
1949 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
|
|
1950 | its built-in modules) are required to use it. |
|
|
1951 | |
|
|
1952 | That does not mean that AnyEvent won't take advantage of some additional |
|
|
1953 | modules if they are installed. |
|
|
1954 | |
|
|
1955 | This section explains which additional modules will be used, and how |
|
|
1956 | they affect AnyEvent's operation. |
|
|
1957 | |
|
|
1958 | Async::Interrupt |
|
|
1959 | This slightly arcane module is used to implement fast signal |
|
|
1960 | handling: To my knowledge, there is no way to do completely |
|
|
1961 | race-free and quick signal handling in pure perl. To ensure that |
|
|
1962 | signals still get delivered, AnyEvent will start an interval timer |
|
|
1963 | to wake up perl (and catch the signals) with some delay (default is |
|
|
1964 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1965 | |
|
|
1966 | If this module is available, then it will be used to implement |
|
|
1967 | signal catching, which means that signals will not be delayed, and |
|
|
1968 | the event loop will not be interrupted regularly, which is more |
|
|
1969 | efficient (and good for battery life on laptops). |
|
|
1970 | |
|
|
1971 | This affects not just the pure-perl event loop, but also other event |
|
|
1972 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
|
|
1973 | |
|
|
1974 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
|
|
1975 | natively, and either employ their own workarounds (POE) or use |
|
|
1976 | AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1977 | Installing Async::Interrupt does nothing for those backends. |
|
|
1978 | |
|
|
1979 | EV This module isn't really "optional", as it is simply one of the |
|
|
1980 | backend event loops that AnyEvent can use. However, it is simply the |
|
|
1981 | best event loop available in terms of features, speed and stability: |
|
|
1982 | It supports the AnyEvent API optimally, implements all the watcher |
|
|
1983 | types in XS, does automatic timer adjustments even when no monotonic |
|
|
1984 | clock is available, can take avdantage of advanced kernel interfaces |
|
|
1985 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
|
|
1986 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
|
|
1987 | Glib::EV). |
|
|
1988 | |
|
|
1989 | If you only use backends that rely on another event loop (e.g. |
|
|
1990 | "Tk"), then this module will do nothing for you. |
|
|
1991 | |
|
|
1992 | Guard |
|
|
1993 | The guard module, when used, will be used to implement |
|
|
1994 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
|
|
1995 | uses a lot less memory), but otherwise doesn't affect guard |
|
|
1996 | operation much. It is purely used for performance. |
|
|
1997 | |
|
|
1998 | JSON and JSON::XS |
|
|
1999 | One of these modules is required when you want to read or write JSON |
|
|
2000 | data via AnyEvent::Handle. JSON is also written in pure-perl, but |
|
|
2001 | can take advantage of the ultra-high-speed JSON::XS module when it |
|
|
2002 | is installed. |
|
|
2003 | |
|
|
2004 | Net::SSLeay |
|
|
2005 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
|
|
2006 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
|
|
2007 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
|
|
2008 | |
|
|
2009 | Time::HiRes |
|
|
2010 | This module is part of perl since release 5.008. It will be used |
|
|
2011 | when the chosen event library does not come with a timing source of |
|
|
2012 | its own. The pure-perl event loop (AnyEvent::Loop) will additionally |
|
|
2013 | load it to try to use a monotonic clock for timing stability. |
|
|
2014 | |
|
|
2015 | AnyEvent::AIO (and IO::AIO) |
|
|
2016 | The default implementation of AnyEvent::IO is to do I/O |
|
|
2017 | synchronously, stopping programs while they access the disk, which |
|
|
2018 | is fine for a lot of programs. |
|
|
2019 | |
|
|
2020 | Installing AnyEvent::AIO (and its IO::AIO dependency) makes it |
|
|
2021 | switch to a true asynchronous implementation, so event processing |
|
|
2022 | can continue even while waiting for disk I/O. |
|
|
2023 | |
|
|
2024 | FORK |
|
|
2025 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
2026 | because they rely on inefficient but fork-safe "select" or "poll" calls |
|
|
2027 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
|
|
2028 | epoll are usually badly thought-out hacks that are incompatible with |
|
|
2029 | fork in one way or another. Only EV is fully fork-aware and ensures that |
|
|
2030 | you continue event-processing in both parent and child (or both, if you |
|
|
2031 | know what you are doing). |
|
|
2032 | |
|
|
2033 | This means that, in general, you cannot fork and do event processing in |
|
|
2034 | the child if the event library was initialised before the fork (which |
|
|
2035 | usually happens when the first AnyEvent watcher is created, or the |
|
|
2036 | library is loaded). |
|
|
2037 | |
|
|
2038 | If you have to fork, you must either do so *before* creating your first |
|
|
2039 | watcher OR you must not use AnyEvent at all in the child OR you must do |
|
|
2040 | something completely out of the scope of AnyEvent. |
|
|
2041 | |
|
|
2042 | The problem of doing event processing in the parent *and* the child is |
|
|
2043 | much more complicated: even for backends that *are* fork-aware or |
|
|
2044 | fork-safe, their behaviour is not usually what you want: fork clones all |
|
|
2045 | watchers, that means all timers, I/O watchers etc. are active in both |
|
|
2046 | parent and child, which is almost never what you want. USing "exec" to |
|
|
2047 | start worker children from some kind of manage rprocess is usually |
|
|
2048 | preferred, because it is much easier and cleaner, at the expense of |
|
|
2049 | having to have another binary. |
|
|
2050 | |
|
|
2051 | SECURITY CONSIDERATIONS |
|
|
2052 | AnyEvent can be forced to load any event model via |
|
|
2053 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
|
|
2054 | to execute arbitrary code or directly gain access, it can easily be used |
|
|
2055 | to make the program hang or malfunction in subtle ways, as AnyEvent |
|
|
2056 | watchers will not be active when the program uses a different event |
|
|
2057 | model than specified in the variable. |
|
|
2058 | |
|
|
2059 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
2060 | before the first watcher gets created, e.g. with a "BEGIN" block: |
|
|
2061 | |
|
|
2062 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
2063 | |
|
|
2064 | use AnyEvent; |
|
|
2065 | |
|
|
2066 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
2067 | be used to probe what backend is used and gain other information (which |
|
|
2068 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
|
|
2069 | and $ENV{PERL_ANYEVENT_STRICT}. |
|
|
2070 | |
|
|
2071 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
2072 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
2073 | enabled. |
|
|
2074 | |
|
|
2075 | BUGS |
|
|
2076 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
|
|
2077 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
|
|
2078 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
|
|
2079 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
|
|
2080 | not as pronounced). |
383 | |
2081 | |
384 | SEE ALSO |
2082 | SEE ALSO |
385 | Event modules: Coro::Event, Coro, Event, Glib::Event, Glib. |
2083 | Tutorial/Introduction: AnyEvent::Intro. |
386 | |
2084 | |
|
|
2085 | FAQ: AnyEvent::FAQ. |
|
|
2086 | |
|
|
2087 | Utility functions: AnyEvent::Util (misc. grab-bag), AnyEvent::Log |
|
|
2088 | (simply logging). |
|
|
2089 | |
|
|
2090 | Development/Debugging: AnyEvent::Strict (stricter checking), |
|
|
2091 | AnyEvent::Debug (interactive shell, watcher tracing). |
|
|
2092 | |
|
|
2093 | Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event, |
|
|
2094 | Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK. |
|
|
2095 | |
387 | Implementations: AnyEvent::Impl::Coro, AnyEvent::Impl::Event, |
2096 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
388 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk. |
2097 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
|
|
2098 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
|
|
2099 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi, AnyEvent::Impl::FLTK. |
389 | |
2100 | |
390 | Nontrivial usage example: Net::FCP. |
2101 | Non-blocking handles, pipes, stream sockets, TCP clients and servers: |
|
|
2102 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
391 | |
2103 | |
|
|
2104 | Asynchronous File I/O: AnyEvent::IO. |
392 | |
2105 | |
|
|
2106 | Asynchronous DNS: AnyEvent::DNS. |
|
|
2107 | |
|
|
2108 | Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. |
|
|
2109 | |
|
|
2110 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, |
|
|
2111 | AnyEvent::HTTP. |
|
|
2112 | |
|
|
2113 | AUTHOR |
|
|
2114 | Marc Lehmann <schmorp@schmorp.de> |
|
|
2115 | http://anyevent.schmorp.de |
|
|
2116 | |