1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | AnyEvent - ??? |
3 | AnyEvent - provide framework for multiple event loops |
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4 | |
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5 | EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
4 | |
6 | |
5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
6 | |
8 | |
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9 | use AnyEvent; |
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10 | |
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11 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
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12 | ... |
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13 | }); |
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14 | |
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15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
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16 | ... |
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17 | }); |
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18 | |
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19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
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21 | $w->broadcast; # wake up current and all future wait's |
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22 | |
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23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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24 | |
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25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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26 | nowadays. So what is different about AnyEvent? |
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27 | |
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28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
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29 | policy> and AnyEvent is I<small and efficient>. |
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30 | |
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31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
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32 | interfaces to whatever event model the main program happens to use in a |
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33 | pragmatic way. For event models and certain classes of immortals alike, |
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34 | the statement "there can only be one" is a bitter reality: In general, |
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35 | only one event loop can be active at the same time in a process. AnyEvent |
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36 | helps hiding the differences between those event loops. |
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37 | |
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38 | The goal of AnyEvent is to offer module authors the ability to do event |
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39 | programming (waiting for I/O or timer events) without subscribing to a |
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40 | religion, a way of living, and most importantly: without forcing your |
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41 | module users into the same thing by forcing them to use the same event |
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42 | model you use. |
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43 | |
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44 | For modules like POE or IO::Async (which is a total misnomer as it is |
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45 | actually doing all I/O I<synchronously>...), using them in your module is |
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46 | like joining a cult: After you joined, you are dependent on them and you |
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47 | cannot use anything else, as it is simply incompatible to everything that |
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48 | isn't itself. What's worse, all the potential users of your module are |
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49 | I<also> forced to use the same event loop you use. |
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50 | |
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51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
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52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
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53 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if |
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54 | your module uses one of those, every user of your module has to use it, |
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55 | too. But if your module uses AnyEvent, it works transparently with all |
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56 | event models it supports (including stuff like POE and IO::Async, as long |
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57 | as those use one of the supported event loops. It is trivial to add new |
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58 | event loops to AnyEvent, too, so it is future-proof). |
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59 | |
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60 | In addition to being free of having to use I<the one and only true event |
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61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
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62 | modules, you get an enourmous amount of code and strict rules you have to |
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63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
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64 | offering the functionality that is necessary, in as thin as a wrapper as |
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65 | technically possible. |
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66 | |
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67 | Of course, if you want lots of policy (this can arguably be somewhat |
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68 | useful) and you want to force your users to use the one and only event |
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69 | model, you should I<not> use this module. |
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70 | |
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71 | |
7 | =head1 DESCRIPTION |
72 | =head1 DESCRIPTION |
8 | |
73 | |
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74 | L<AnyEvent> provides an identical interface to multiple event loops. This |
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75 | allows module authors to utilise an event loop without forcing module |
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76 | users to use the same event loop (as only a single event loop can coexist |
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77 | peacefully at any one time). |
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78 | |
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79 | The interface itself is vaguely similar, but not identical to the L<Event> |
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80 | module. |
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81 | |
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82 | During the first call of any watcher-creation method, the module tries |
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83 | to detect the currently loaded event loop by probing whether one of the |
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84 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
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85 | L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>, |
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86 | L<POE>. The first one found is used. If none are found, the module tries |
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87 | to load these modules (excluding Event::Lib, Qt and POE as the pure perl |
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88 | adaptor should always succeed) in the order given. The first one that can |
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89 | be successfully loaded will be used. If, after this, still none could be |
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90 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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91 | very efficient, but should work everywhere. |
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92 | |
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93 | Because AnyEvent first checks for modules that are already loaded, loading |
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94 | an event model explicitly before first using AnyEvent will likely make |
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95 | that model the default. For example: |
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96 | |
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97 | use Tk; |
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98 | use AnyEvent; |
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99 | |
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100 | # .. AnyEvent will likely default to Tk |
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101 | |
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102 | The I<likely> means that, if any module loads another event model and |
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103 | starts using it, all bets are off. Maybe you should tell their authors to |
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104 | use AnyEvent so their modules work together with others seamlessly... |
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105 | |
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106 | The pure-perl implementation of AnyEvent is called |
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107 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
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108 | explicitly. |
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109 | |
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110 | =head1 WATCHERS |
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111 | |
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112 | AnyEvent has the central concept of a I<watcher>, which is an object that |
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113 | stores relevant data for each kind of event you are waiting for, such as |
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114 | the callback to call, the filehandle to watch, etc. |
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115 | |
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116 | These watchers are normal Perl objects with normal Perl lifetime. After |
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117 | creating a watcher it will immediately "watch" for events and invoke the |
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118 | callback when the event occurs (of course, only when the event model |
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119 | is in control). |
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120 | |
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121 | To disable the watcher you have to destroy it (e.g. by setting the |
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122 | variable you store it in to C<undef> or otherwise deleting all references |
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123 | to it). |
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124 | |
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125 | All watchers are created by calling a method on the C<AnyEvent> class. |
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126 | |
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127 | Many watchers either are used with "recursion" (repeating timers for |
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128 | example), or need to refer to their watcher object in other ways. |
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129 | |
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130 | An any way to achieve that is this pattern: |
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131 | |
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132 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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133 | # you can use $w here, for example to undef it |
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134 | undef $w; |
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135 | }); |
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136 | |
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137 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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138 | my variables are only visible after the statement in which they are |
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139 | declared. |
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140 | |
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141 | =head2 IO WATCHERS |
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142 | |
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143 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
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144 | with the following mandatory key-value pairs as arguments: |
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145 | |
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146 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for |
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147 | events. C<poll> must be a string that is either C<r> or C<w>, which |
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148 | creates a watcher waiting for "r"eadable or "w"ritable events, |
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149 | respectively. C<cb> is the callback to invoke each time the file handle |
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150 | becomes ready. |
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151 | |
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152 | As long as the I/O watcher exists it will keep the file descriptor or a |
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153 | copy of it alive/open. |
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154 | |
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155 | It is not allowed to close a file handle as long as any watcher is active |
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156 | on the underlying file descriptor. |
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157 | |
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158 | Some event loops issue spurious readyness notifications, so you should |
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159 | always use non-blocking calls when reading/writing from/to your file |
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160 | handles. |
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161 | |
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162 | Example: |
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163 | |
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164 | # wait for readability of STDIN, then read a line and disable the watcher |
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165 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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166 | chomp (my $input = <STDIN>); |
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167 | warn "read: $input\n"; |
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168 | undef $w; |
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169 | }); |
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170 | |
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171 | =head2 TIME WATCHERS |
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172 | |
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173 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
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174 | method with the following mandatory arguments: |
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175 | |
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176 | C<after> specifies after how many seconds (fractional values are |
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177 | supported) should the timer activate. C<cb> the callback to invoke in that |
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178 | case. |
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179 | |
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180 | The timer callback will be invoked at most once: if you want a repeating |
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181 | timer you have to create a new watcher (this is a limitation by both Tk |
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182 | and Glib). |
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183 | |
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184 | Example: |
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185 | |
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186 | # fire an event after 7.7 seconds |
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187 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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188 | warn "timeout\n"; |
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189 | }); |
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190 | |
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191 | # to cancel the timer: |
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192 | undef $w; |
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193 | |
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194 | Example 2: |
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195 | |
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196 | # fire an event after 0.5 seconds, then roughly every second |
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197 | my $w; |
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198 | |
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199 | my $cb = sub { |
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200 | # cancel the old timer while creating a new one |
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201 | $w = AnyEvent->timer (after => 1, cb => $cb); |
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202 | }; |
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203 | |
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204 | # start the "loop" by creating the first watcher |
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205 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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206 | |
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207 | =head3 TIMING ISSUES |
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208 | |
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209 | There are two ways to handle timers: based on real time (relative, "fire |
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210 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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211 | o'clock"). |
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212 | |
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213 | While most event loops expect timers to specified in a relative way, they |
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214 | use absolute time internally. This makes a difference when your clock |
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215 | "jumps", for example, when ntp decides to set your clock backwards from |
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216 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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217 | fire "after" a second might actually take six years to finally fire. |
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218 | |
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219 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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220 | about these issues is L<EV>, which offers both relative (ev_timer, based |
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221 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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222 | timers. |
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223 | |
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224 | AnyEvent always prefers relative timers, if available, matching the |
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225 | AnyEvent API. |
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226 | |
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227 | =head2 SIGNAL WATCHERS |
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228 | |
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229 | You can watch for signals using a signal watcher, C<signal> is the signal |
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230 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
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231 | be invoked whenever a signal occurs. |
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232 | |
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233 | Multiple signal occurances can be clumped together into one callback |
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234 | invocation, and callback invocation will be synchronous. synchronous means |
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235 | that it might take a while until the signal gets handled by the process, |
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236 | but it is guarenteed not to interrupt any other callbacks. |
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237 | |
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238 | The main advantage of using these watchers is that you can share a signal |
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239 | between multiple watchers. |
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240 | |
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241 | This watcher might use C<%SIG>, so programs overwriting those signals |
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242 | directly will likely not work correctly. |
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243 | |
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244 | Example: exit on SIGINT |
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245 | |
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246 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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247 | |
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248 | =head2 CHILD PROCESS WATCHERS |
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249 | |
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250 | You can also watch on a child process exit and catch its exit status. |
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251 | |
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252 | The child process is specified by the C<pid> argument (if set to C<0>, it |
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253 | watches for any child process exit). The watcher will trigger as often |
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254 | as status change for the child are received. This works by installing a |
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255 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
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256 | and exit status (as returned by waitpid). |
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257 | |
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258 | Example: wait for pid 1333 |
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259 | |
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260 | my $w = AnyEvent->child ( |
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261 | pid => 1333, |
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262 | cb => sub { |
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263 | my ($pid, $status) = @_; |
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264 | warn "pid $pid exited with status $status"; |
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265 | }, |
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266 | ); |
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267 | |
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268 | =head2 CONDITION VARIABLES |
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269 | |
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270 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
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271 | method without any arguments. |
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272 | |
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273 | A condition variable waits for a condition - precisely that the C<< |
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274 | ->broadcast >> method has been called. |
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275 | |
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276 | They are very useful to signal that a condition has been fulfilled, for |
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277 | example, if you write a module that does asynchronous http requests, |
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278 | then a condition variable would be the ideal candidate to signal the |
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279 | availability of results. |
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280 | |
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281 | You can also use condition variables to block your main program until |
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282 | an event occurs - for example, you could C<< ->wait >> in your main |
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283 | program until the user clicks the Quit button in your app, which would C<< |
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284 | ->broadcast >> the "quit" event. |
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285 | |
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286 | Note that condition variables recurse into the event loop - if you have |
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287 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
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288 | lose. Therefore, condition variables are good to export to your caller, but |
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289 | you should avoid making a blocking wait yourself, at least in callbacks, |
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290 | as this asks for trouble. |
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291 | |
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292 | This object has two methods: |
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293 | |
9 | =over 4 |
294 | =over 4 |
10 | |
295 | |
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296 | =item $cv->wait |
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297 | |
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298 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
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299 | called on c<$cv>, while servicing other watchers normally. |
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300 | |
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301 | You can only wait once on a condition - additional calls will return |
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302 | immediately. |
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303 | |
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304 | Not all event models support a blocking wait - some die in that case |
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305 | (programs might want to do that to stay interactive), so I<if you are |
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306 | using this from a module, never require a blocking wait>, but let the |
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307 | caller decide whether the call will block or not (for example, by coupling |
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308 | condition variables with some kind of request results and supporting |
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309 | callbacks so the caller knows that getting the result will not block, |
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310 | while still suppporting blocking waits if the caller so desires). |
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311 | |
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312 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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313 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
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314 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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315 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
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316 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
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317 | from different coroutines, however). |
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318 | |
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319 | =item $cv->broadcast |
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320 | |
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321 | Flag the condition as ready - a running C<< ->wait >> and all further |
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322 | calls to C<wait> will (eventually) return after this method has been |
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323 | called. If nobody is waiting the broadcast will be remembered.. |
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324 | |
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325 | =back |
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326 | |
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327 | Example: |
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328 | |
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329 | # wait till the result is ready |
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330 | my $result_ready = AnyEvent->condvar; |
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331 | |
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332 | # do something such as adding a timer |
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333 | # or socket watcher the calls $result_ready->broadcast |
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334 | # when the "result" is ready. |
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335 | # in this case, we simply use a timer: |
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336 | my $w = AnyEvent->timer ( |
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337 | after => 1, |
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338 | cb => sub { $result_ready->broadcast }, |
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339 | ); |
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340 | |
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341 | # this "blocks" (while handling events) till the watcher |
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342 | # calls broadcast |
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343 | $result_ready->wait; |
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344 | |
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345 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
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346 | |
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347 | =over 4 |
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348 | |
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349 | =item $AnyEvent::MODEL |
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350 | |
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351 | Contains C<undef> until the first watcher is being created. Then it |
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352 | contains the event model that is being used, which is the name of the |
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353 | Perl class implementing the model. This class is usually one of the |
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354 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
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355 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
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356 | |
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357 | The known classes so far are: |
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358 | |
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359 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
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360 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
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361 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
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362 | AnyEvent::Impl::Event based on Event, second best choice. |
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363 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
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364 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
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365 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
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366 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
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367 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
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368 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
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369 | |
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370 | There is no support for WxWidgets, as WxWidgets has no support for |
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371 | watching file handles. However, you can use WxWidgets through the |
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372 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
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373 | second, which was considered to be too horrible to even consider for |
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374 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
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375 | it's adaptor. |
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376 | |
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377 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
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378 | autodetecting them. |
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379 | |
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380 | =item AnyEvent::detect |
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381 | |
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382 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
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383 | if necessary. You should only call this function right before you would |
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384 | have created an AnyEvent watcher anyway, that is, as late as possible at |
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385 | runtime. |
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386 | |
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387 | =back |
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388 | |
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389 | =head1 WHAT TO DO IN A MODULE |
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390 | |
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391 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
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392 | freely, but you should not load a specific event module or rely on it. |
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393 | |
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394 | Be careful when you create watchers in the module body - AnyEvent will |
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395 | decide which event module to use as soon as the first method is called, so |
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396 | by calling AnyEvent in your module body you force the user of your module |
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397 | to load the event module first. |
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398 | |
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399 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
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400 | the C<< ->broadcast >> method has been called on it already. This is |
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401 | because it will stall the whole program, and the whole point of using |
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402 | events is to stay interactive. |
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403 | |
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404 | It is fine, however, to call C<< ->wait >> when the user of your module |
|
|
405 | requests it (i.e. if you create a http request object ad have a method |
|
|
406 | called C<results> that returns the results, it should call C<< ->wait >> |
|
|
407 | freely, as the user of your module knows what she is doing. always). |
|
|
408 | |
|
|
409 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
|
|
410 | |
|
|
411 | There will always be a single main program - the only place that should |
|
|
412 | dictate which event model to use. |
|
|
413 | |
|
|
414 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
|
|
415 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
416 | decide which implementation to chose if some module relies on it. |
|
|
417 | |
|
|
418 | If the main program relies on a specific event model. For example, in |
|
|
419 | Gtk2 programs you have to rely on the Glib module. You should load the |
|
|
420 | event module before loading AnyEvent or any module that uses it: generally |
|
|
421 | speaking, you should load it as early as possible. The reason is that |
|
|
422 | modules might create watchers when they are loaded, and AnyEvent will |
|
|
423 | decide on the event model to use as soon as it creates watchers, and it |
|
|
424 | might chose the wrong one unless you load the correct one yourself. |
|
|
425 | |
|
|
426 | You can chose to use a rather inefficient pure-perl implementation by |
|
|
427 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
|
|
428 | behaviour everywhere, but letting AnyEvent chose is generally better. |
|
|
429 | |
11 | =cut |
430 | =cut |
12 | |
431 | |
13 | package AnyEvent; |
432 | package AnyEvent; |
14 | |
433 | |
|
|
434 | no warnings; |
|
|
435 | use strict; |
|
|
436 | |
15 | use Carp; |
437 | use Carp; |
16 | |
438 | |
17 | $VERSION = 0.1; |
439 | our $VERSION = '3.3'; |
|
|
440 | our $MODEL; |
18 | |
441 | |
19 | no warnings; |
442 | our $AUTOLOAD; |
|
|
443 | our @ISA; |
|
|
444 | |
|
|
445 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
|
|
446 | |
|
|
447 | our @REGISTRY; |
20 | |
448 | |
21 | my @models = ( |
449 | my @models = ( |
22 | [Coro => Coro::Event::], |
450 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
23 | [Event => Event::], |
451 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
24 | [Glib => Glib::], |
452 | [EV:: => AnyEvent::Impl::EV::], |
25 | [Tk => Tk::], |
453 | [Event:: => AnyEvent::Impl::Event::], |
|
|
454 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
455 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
456 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
457 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
458 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
459 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
|
|
460 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
461 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
462 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
26 | ); |
463 | ); |
27 | |
464 | |
|
|
465 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
|
|
466 | |
|
|
467 | sub detect() { |
|
|
468 | unless ($MODEL) { |
|
|
469 | no strict 'refs'; |
|
|
470 | |
|
|
471 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
472 | my $model = "AnyEvent::Impl::$1"; |
|
|
473 | if (eval "require $model") { |
|
|
474 | $MODEL = $model; |
|
|
475 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
476 | } else { |
|
|
477 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
478 | } |
|
|
479 | } |
|
|
480 | |
|
|
481 | # check for already loaded models |
|
|
482 | unless ($MODEL) { |
|
|
483 | for (@REGISTRY, @models) { |
|
|
484 | my ($package, $model) = @$_; |
|
|
485 | if (${"$package\::VERSION"} > 0) { |
|
|
486 | if (eval "require $model") { |
|
|
487 | $MODEL = $model; |
|
|
488 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
|
|
489 | last; |
|
|
490 | } |
|
|
491 | } |
|
|
492 | } |
|
|
493 | |
|
|
494 | unless ($MODEL) { |
|
|
495 | # try to load a model |
|
|
496 | |
|
|
497 | for (@REGISTRY, @models) { |
|
|
498 | my ($package, $model) = @$_; |
|
|
499 | if (eval "require $package" |
|
|
500 | and ${"$package\::VERSION"} > 0 |
|
|
501 | and eval "require $model") { |
|
|
502 | $MODEL = $model; |
|
|
503 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
|
|
504 | last; |
|
|
505 | } |
|
|
506 | } |
|
|
507 | |
|
|
508 | $MODEL |
|
|
509 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; |
|
|
510 | } |
|
|
511 | } |
|
|
512 | |
|
|
513 | unshift @ISA, $MODEL; |
|
|
514 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
|
|
515 | } |
|
|
516 | |
|
|
517 | $MODEL |
|
|
518 | } |
|
|
519 | |
28 | sub AUTOLOAD { |
520 | sub AUTOLOAD { |
29 | $AUTOLOAD =~ s/.*://; |
521 | (my $func = $AUTOLOAD) =~ s/.*://; |
30 | |
522 | |
31 | for (@models) { |
523 | $method{$func} |
32 | my ($model, $package) = @$_; |
524 | or croak "$func: not a valid method for AnyEvent objects"; |
33 | if (defined ${"$package\::VERSION"}) { |
525 | |
34 | $EVENT = "AnyEvent::Impl::$model"; |
526 | detect unless $MODEL; |
35 | eval "require $EVENT"; die if $@; |
527 | |
36 | goto &{"$EVENT\::$AUTOLOAD"}; |
528 | my $class = shift; |
37 | } |
529 | $class->$func (@_); |
|
|
530 | } |
|
|
531 | |
|
|
532 | package AnyEvent::Base; |
|
|
533 | |
|
|
534 | # default implementation for ->condvar, ->wait, ->broadcast |
|
|
535 | |
|
|
536 | sub condvar { |
|
|
537 | bless \my $flag, "AnyEvent::Base::CondVar" |
|
|
538 | } |
|
|
539 | |
|
|
540 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
541 | ${$_[0]}++; |
|
|
542 | } |
|
|
543 | |
|
|
544 | sub AnyEvent::Base::CondVar::wait { |
|
|
545 | AnyEvent->one_event while !${$_[0]}; |
|
|
546 | } |
|
|
547 | |
|
|
548 | # default implementation for ->signal |
|
|
549 | |
|
|
550 | our %SIG_CB; |
|
|
551 | |
|
|
552 | sub signal { |
|
|
553 | my (undef, %arg) = @_; |
|
|
554 | |
|
|
555 | my $signal = uc $arg{signal} |
|
|
556 | or Carp::croak "required option 'signal' is missing"; |
|
|
557 | |
|
|
558 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
|
|
559 | $SIG{$signal} ||= sub { |
|
|
560 | $_->() for values %{ $SIG_CB{$signal} || {} }; |
|
|
561 | }; |
|
|
562 | |
|
|
563 | bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
|
|
564 | } |
|
|
565 | |
|
|
566 | sub AnyEvent::Base::Signal::DESTROY { |
|
|
567 | my ($signal, $cb) = @{$_[0]}; |
|
|
568 | |
|
|
569 | delete $SIG_CB{$signal}{$cb}; |
|
|
570 | |
|
|
571 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
|
|
572 | } |
|
|
573 | |
|
|
574 | # default implementation for ->child |
|
|
575 | |
|
|
576 | our %PID_CB; |
|
|
577 | our $CHLD_W; |
|
|
578 | our $CHLD_DELAY_W; |
|
|
579 | our $PID_IDLE; |
|
|
580 | our $WNOHANG; |
|
|
581 | |
|
|
582 | sub _child_wait { |
|
|
583 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
|
|
584 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
|
|
585 | (values %{ $PID_CB{0} || {} }); |
38 | } |
586 | } |
39 | |
587 | |
40 | for (@models) { |
588 | undef $PID_IDLE; |
41 | my ($model, $package) = @$_; |
589 | } |
42 | $EVENT = "AnyEvent::Impl::$model"; |
590 | |
43 | if (eval "require $EVENT") { |
591 | sub _sigchld { |
44 | goto &{"$EVENT\::$AUTOLOAD"}; |
592 | # make sure we deliver these changes "synchronous" with the event loop. |
45 | } |
593 | $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
|
|
594 | undef $CHLD_DELAY_W; |
|
|
595 | &_child_wait; |
|
|
596 | }); |
|
|
597 | } |
|
|
598 | |
|
|
599 | sub child { |
|
|
600 | my (undef, %arg) = @_; |
|
|
601 | |
|
|
602 | defined (my $pid = $arg{pid} + 0) |
|
|
603 | or Carp::croak "required option 'pid' is missing"; |
|
|
604 | |
|
|
605 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
|
|
606 | |
|
|
607 | unless ($WNOHANG) { |
|
|
608 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
46 | } |
609 | } |
47 | |
610 | |
48 | die "No event module selected for AnyEvent and autodetect failed. Install any of these: Coro, Event, Glib or Tk."; |
611 | unless ($CHLD_W) { |
49 | } |
612 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
|
|
613 | # child could be a zombie already, so make at least one round |
|
|
614 | &_sigchld; |
|
|
615 | } |
50 | |
616 | |
51 | 1; |
617 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
|
|
618 | } |
52 | |
619 | |
|
|
620 | sub AnyEvent::Base::Child::DESTROY { |
|
|
621 | my ($pid, $cb) = @{$_[0]}; |
|
|
622 | |
|
|
623 | delete $PID_CB{$pid}{$cb}; |
|
|
624 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
|
|
625 | |
|
|
626 | undef $CHLD_W unless keys %PID_CB; |
|
|
627 | } |
|
|
628 | |
|
|
629 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
630 | |
|
|
631 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
632 | a module. This section is only of use to event loop authors who want to |
|
|
633 | provide AnyEvent compatibility. |
|
|
634 | |
|
|
635 | If you need to support another event library which isn't directly |
|
|
636 | supported by AnyEvent, you can supply your own interface to it by |
|
|
637 | pushing, before the first watcher gets created, the package name of |
|
|
638 | the event module and the package name of the interface to use onto |
|
|
639 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
|
|
640 | AnyEvent, so it is reasonably cheap. |
|
|
641 | |
|
|
642 | Example: |
|
|
643 | |
|
|
644 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
645 | |
|
|
646 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
|
|
647 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
648 | |
|
|
649 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
650 | will first check for the presence of urxvt by trying to C<use> the |
|
|
651 | C<urxvt::anyevent> module. |
|
|
652 | |
|
|
653 | The class should provide implementations for all watcher types. See |
|
|
654 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
|
|
655 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
|
|
656 | see the sources. |
|
|
657 | |
|
|
658 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
659 | provide suitable (hopefully) replacements. |
|
|
660 | |
|
|
661 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
|
|
662 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
663 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
|
|
664 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
|
|
665 | I<rxvt-unicode> distribution. |
|
|
666 | |
|
|
667 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
|
|
668 | condition variables: code blocking while waiting for a condition will |
|
|
669 | C<die>. This still works with most modules/usages, and blocking calls must |
|
|
670 | not be done in an interactive application, so it makes sense. |
|
|
671 | |
|
|
672 | =head1 ENVIRONMENT VARIABLES |
|
|
673 | |
|
|
674 | The following environment variables are used by this module: |
|
|
675 | |
|
|
676 | =over 4 |
|
|
677 | |
|
|
678 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
679 | |
|
|
680 | By default, AnyEvent will be completely silent except in fatal |
|
|
681 | conditions. You can set this environment variable to make AnyEvent more |
|
|
682 | talkative. |
|
|
683 | |
|
|
684 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
685 | conditions, such as not being able to load the event model specified by |
|
|
686 | C<PERL_ANYEVENT_MODEL>. |
|
|
687 | |
|
|
688 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
689 | model it chooses. |
|
|
690 | |
|
|
691 | =item C<PERL_ANYEVENT_MODEL> |
|
|
692 | |
|
|
693 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
694 | autodetection and -probing kicks in. It must be a string consisting |
|
|
695 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
696 | and the resulting module name is loaded and if the load was successful, |
|
|
697 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
698 | autodetection and -probing. |
|
|
699 | |
|
|
700 | This functionality might change in future versions. |
|
|
701 | |
|
|
702 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
703 | could start your program like this: |
|
|
704 | |
|
|
705 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
706 | |
|
|
707 | =back |
|
|
708 | |
|
|
709 | =head1 EXAMPLE PROGRAM |
|
|
710 | |
|
|
711 | The following program uses an IO watcher to read data from STDIN, a timer |
|
|
712 | to display a message once per second, and a condition variable to quit the |
|
|
713 | program when the user enters quit: |
|
|
714 | |
|
|
715 | use AnyEvent; |
|
|
716 | |
|
|
717 | my $cv = AnyEvent->condvar; |
|
|
718 | |
|
|
719 | my $io_watcher = AnyEvent->io ( |
|
|
720 | fh => \*STDIN, |
|
|
721 | poll => 'r', |
|
|
722 | cb => sub { |
|
|
723 | warn "io event <$_[0]>\n"; # will always output <r> |
|
|
724 | chomp (my $input = <STDIN>); # read a line |
|
|
725 | warn "read: $input\n"; # output what has been read |
|
|
726 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
|
|
727 | }, |
|
|
728 | ); |
|
|
729 | |
|
|
730 | my $time_watcher; # can only be used once |
|
|
731 | |
|
|
732 | sub new_timer { |
|
|
733 | $timer = AnyEvent->timer (after => 1, cb => sub { |
|
|
734 | warn "timeout\n"; # print 'timeout' about every second |
|
|
735 | &new_timer; # and restart the time |
|
|
736 | }); |
|
|
737 | } |
|
|
738 | |
|
|
739 | new_timer; # create first timer |
|
|
740 | |
|
|
741 | $cv->wait; # wait until user enters /^q/i |
|
|
742 | |
|
|
743 | =head1 REAL-WORLD EXAMPLE |
|
|
744 | |
|
|
745 | Consider the L<Net::FCP> module. It features (among others) the following |
|
|
746 | API calls, which are to freenet what HTTP GET requests are to http: |
|
|
747 | |
|
|
748 | my $data = $fcp->client_get ($url); # blocks |
|
|
749 | |
|
|
750 | my $transaction = $fcp->txn_client_get ($url); # does not block |
|
|
751 | $transaction->cb ( sub { ... } ); # set optional result callback |
|
|
752 | my $data = $transaction->result; # possibly blocks |
|
|
753 | |
|
|
754 | The C<client_get> method works like C<LWP::Simple::get>: it requests the |
|
|
755 | given URL and waits till the data has arrived. It is defined to be: |
|
|
756 | |
|
|
757 | sub client_get { $_[0]->txn_client_get ($_[1])->result } |
|
|
758 | |
|
|
759 | And in fact is automatically generated. This is the blocking API of |
|
|
760 | L<Net::FCP>, and it works as simple as in any other, similar, module. |
|
|
761 | |
|
|
762 | More complicated is C<txn_client_get>: It only creates a transaction |
|
|
763 | (completion, result, ...) object and initiates the transaction. |
|
|
764 | |
|
|
765 | my $txn = bless { }, Net::FCP::Txn::; |
|
|
766 | |
|
|
767 | It also creates a condition variable that is used to signal the completion |
|
|
768 | of the request: |
|
|
769 | |
|
|
770 | $txn->{finished} = AnyAvent->condvar; |
|
|
771 | |
|
|
772 | It then creates a socket in non-blocking mode. |
|
|
773 | |
|
|
774 | socket $txn->{fh}, ...; |
|
|
775 | fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
|
|
776 | connect $txn->{fh}, ... |
|
|
777 | and !$!{EWOULDBLOCK} |
|
|
778 | and !$!{EINPROGRESS} |
|
|
779 | and Carp::croak "unable to connect: $!\n"; |
|
|
780 | |
|
|
781 | Then it creates a write-watcher which gets called whenever an error occurs |
|
|
782 | or the connection succeeds: |
|
|
783 | |
|
|
784 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
|
|
785 | |
|
|
786 | And returns this transaction object. The C<fh_ready_w> callback gets |
|
|
787 | called as soon as the event loop detects that the socket is ready for |
|
|
788 | writing. |
|
|
789 | |
|
|
790 | The C<fh_ready_w> method makes the socket blocking again, writes the |
|
|
791 | request data and replaces the watcher by a read watcher (waiting for reply |
|
|
792 | data). The actual code is more complicated, but that doesn't matter for |
|
|
793 | this example: |
|
|
794 | |
|
|
795 | fcntl $txn->{fh}, F_SETFL, 0; |
|
|
796 | syswrite $txn->{fh}, $txn->{request} |
|
|
797 | or die "connection or write error"; |
|
|
798 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
|
|
799 | |
|
|
800 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
|
|
801 | result and signals any possible waiters that the request ahs finished: |
|
|
802 | |
|
|
803 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
|
|
804 | |
|
|
805 | if (end-of-file or data complete) { |
|
|
806 | $txn->{result} = $txn->{buf}; |
|
|
807 | $txn->{finished}->broadcast; |
|
|
808 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
|
|
809 | } |
|
|
810 | |
|
|
811 | The C<result> method, finally, just waits for the finished signal (if the |
|
|
812 | request was already finished, it doesn't wait, of course, and returns the |
|
|
813 | data: |
|
|
814 | |
|
|
815 | $txn->{finished}->wait; |
|
|
816 | return $txn->{result}; |
|
|
817 | |
|
|
818 | The actual code goes further and collects all errors (C<die>s, exceptions) |
|
|
819 | that occured during request processing. The C<result> method detects |
|
|
820 | whether an exception as thrown (it is stored inside the $txn object) |
|
|
821 | and just throws the exception, which means connection errors and other |
|
|
822 | problems get reported tot he code that tries to use the result, not in a |
|
|
823 | random callback. |
|
|
824 | |
|
|
825 | All of this enables the following usage styles: |
|
|
826 | |
|
|
827 | 1. Blocking: |
|
|
828 | |
|
|
829 | my $data = $fcp->client_get ($url); |
|
|
830 | |
|
|
831 | 2. Blocking, but running in parallel: |
|
|
832 | |
|
|
833 | my @datas = map $_->result, |
|
|
834 | map $fcp->txn_client_get ($_), |
|
|
835 | @urls; |
|
|
836 | |
|
|
837 | Both blocking examples work without the module user having to know |
|
|
838 | anything about events. |
|
|
839 | |
|
|
840 | 3a. Event-based in a main program, using any supported event module: |
|
|
841 | |
|
|
842 | use EV; |
|
|
843 | |
|
|
844 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
845 | my $txn = shift; |
|
|
846 | my $data = $txn->result; |
|
|
847 | ... |
|
|
848 | }); |
|
|
849 | |
|
|
850 | EV::loop; |
|
|
851 | |
|
|
852 | 3b. The module user could use AnyEvent, too: |
|
|
853 | |
|
|
854 | use AnyEvent; |
|
|
855 | |
|
|
856 | my $quit = AnyEvent->condvar; |
|
|
857 | |
|
|
858 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
859 | ... |
|
|
860 | $quit->broadcast; |
|
|
861 | }); |
|
|
862 | |
|
|
863 | $quit->wait; |
|
|
864 | |
|
|
865 | |
|
|
866 | =head1 BENCHMARK |
|
|
867 | |
|
|
868 | To give you an idea of the performance an doverheads that AnyEvent adds |
|
|
869 | over the backends, here is a benchmark of various supported backends. The |
|
|
870 | benchmark creates a lot of timers (with zero timeout) and io events |
|
|
871 | (watching STDOUT, a pty, to become writable). |
|
|
872 | |
|
|
873 | Explanation of the fields: |
|
|
874 | |
|
|
875 | I<watcher> is the number of event watchers created/destroyed. Sicne |
|
|
876 | different event models have vastly different performance each backend was |
|
|
877 | handed a number of watchers so that overall runtime is acceptable and |
|
|
878 | similar to all backends (and keep them from crashing). |
|
|
879 | |
|
|
880 | I<bytes> is the number of bytes (as measured by resident set size) used by |
|
|
881 | each watcher. |
|
|
882 | |
|
|
883 | I<create> is the time, in microseconds, to create a single watcher. |
|
|
884 | |
|
|
885 | I<invoke> is the time, in microseconds, used to invoke a simple callback |
|
|
886 | that simply counts down. |
|
|
887 | |
|
|
888 | I<destroy> is the time, in microseconds, to destroy a single watcher. |
|
|
889 | |
|
|
890 | name watcher bytes create invoke destroy comment |
|
|
891 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
892 | EV/Any 100000 610 3.52 0.91 0.75 |
|
|
893 | CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal |
|
|
894 | Perl/Any 10000 654 4.64 1.22 0.77 pure perl implementation |
|
|
895 | Event/Event 10000 523 28.05 21.38 5.22 Event native interface |
|
|
896 | Event/Any 10000 943 34.43 20.48 1.39 |
|
|
897 | Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour |
|
|
898 | Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers |
|
|
899 | POE/Select 2000 6343 94.69 807.65 562.69 POE::Loop::Select |
|
|
900 | POE/Event 2000 6644 108.15 768.19 14.33 POE::Loop::Event |
|
|
901 | |
|
|
902 | Discussion: The benchmark does I<not> bench scalability of the |
|
|
903 | backend. For example a select-based backend (such as the pureperl one) can |
|
|
904 | never compete with a backend using epoll. In this benchmark, only a single |
|
|
905 | filehandle is used. |
|
|
906 | |
|
|
907 | EV is the sole leader regarding speed and memory use, which are both |
|
|
908 | maximal/minimal. Even when going through AnyEvent, there is only one event |
|
|
909 | loop that uses less memory (the Event module natively), and no faster |
|
|
910 | event model. |
|
|
911 | |
|
|
912 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
913 | zero timeout and the use of a single fd hit optimisations in the perl |
|
|
914 | interpreter and the backend itself), but it shows that it adds very little |
|
|
915 | overhead in itself. Like any select-based backend it's performance becomes |
|
|
916 | really bad with lots of file descriptors. |
|
|
917 | |
|
|
918 | The Event module has a relatively high setup and callback invocation cost, |
|
|
919 | but overall scores on the third place. |
|
|
920 | |
|
|
921 | Glib has a little higher memory cost, a bit fster callback invocation and |
|
|
922 | has a similar speed as Event. |
|
|
923 | |
|
|
924 | The Tk backend works relatively well, the fact that it crashes with |
|
|
925 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
926 | precedence over speed. |
|
|
927 | |
|
|
928 | POE, regardless of backend (wether it's pure perl select backend or the |
|
|
929 | Event backend) shows abysmal performance and memory usage: Watchers use |
|
|
930 | almost 30 times as much memory as EV watchers, and 10 times as much memory |
|
|
931 | as both Event or EV via AnyEvent. |
|
|
932 | |
|
|
933 | Summary: using EV through AnyEvent is faster than any other event |
|
|
934 | loop. The overhead AnyEvent adds can be very small, and you should avoid |
|
|
935 | POE like the plague if you want performance or reasonable memory usage. |
|
|
936 | |
|
|
937 | |
|
|
938 | =head1 FORK |
|
|
939 | |
|
|
940 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
941 | because they are so inefficient. Only L<EV> is fully fork-aware. |
|
|
942 | |
|
|
943 | If you have to fork, you must either do so I<before> creating your first |
|
|
944 | watcher OR you must not use AnyEvent at all in the child. |
|
|
945 | |
|
|
946 | |
|
|
947 | =head1 SECURITY CONSIDERATIONS |
|
|
948 | |
|
|
949 | AnyEvent can be forced to load any event model via |
|
|
950 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
951 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
952 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
953 | will not be active when the program uses a different event model than |
|
|
954 | specified in the variable. |
|
|
955 | |
|
|
956 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
957 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
958 | |
|
|
959 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
960 | |
|
|
961 | use AnyEvent; |
|
|
962 | |
|
|
963 | |
|
|
964 | =head1 SEE ALSO |
|
|
965 | |
|
|
966 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
|
|
967 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
|
|
968 | L<Event::Lib>, L<Qt>, L<POE>. |
|
|
969 | |
|
|
970 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
|
|
971 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
|
|
972 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
|
|
973 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
|
|
974 | |
|
|
975 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
|
|
976 | |
|
|
977 | |
|
|
978 | =head1 AUTHOR |
|
|
979 | |
|
|
980 | Marc Lehmann <schmorp@schmorp.de> |
|
|
981 | http://home.schmorp.de/ |
|
|
982 | |
|
|
983 | =cut |
|
|
984 | |
|
|
985 | 1 |
|
|
986 | |