| 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 | Event, Coro, Glib, Tk, Perl - 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 wether 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 | |
| 7 | =head1 DESCRIPTION |
23 | =head1 DESCRIPTION |
| 8 | |
24 | |
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25 | L<AnyEvent> provides an identical interface to multiple event loops. This |
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26 | allows module authors to utilise an event loop without forcing module |
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27 | users to use the same event loop (as only a single event loop can coexist |
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28 | peacefully at any one time). |
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29 | |
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30 | The interface itself is vaguely similar but not identical to the Event |
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31 | module. |
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32 | |
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33 | On the first call of any method, the module tries to detect the currently |
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34 | loaded event loop by probing wether any of the following modules is |
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35 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
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36 | used. If none is found, the module tries to load these modules in the |
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37 | order given. The first one that could be successfully loaded will be |
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38 | used. If still none could be found, AnyEvent will fall back to a pure-perl |
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39 | event loop, which is also not very efficient. |
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40 | |
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41 | Because AnyEvent first checks for modules that are already loaded, loading |
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42 | an Event model explicitly before first using AnyEvent will likely make |
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43 | that model the default. For example: |
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44 | |
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45 | use Tk; |
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46 | use AnyEvent; |
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47 | |
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48 | # .. AnyEvent will likely default to Tk |
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49 | |
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50 | The pure-perl implementation of AnyEvent is called |
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51 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
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52 | explicitly. |
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53 | |
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54 | =head1 WATCHERS |
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55 | |
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56 | AnyEvent has the central concept of a I<watcher>, which is an object that |
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57 | stores relevant data for each kind of event you are waiting for, such as |
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58 | the callback to call, the filehandle to watch, etc. |
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59 | |
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60 | These watchers are normal Perl objects with normal Perl lifetime. After |
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61 | creating a watcher it will immediately "watch" for events and invoke |
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62 | the callback. To disable the watcher you have to destroy it (e.g. by |
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63 | setting the variable that stores it to C<undef> or otherwise deleting all |
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64 | references to it). |
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65 | |
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66 | All watchers are created by calling a method on the C<AnyEvent> class. |
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67 | |
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68 | =head2 IO WATCHERS |
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69 | |
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70 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
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71 | the following mandatory arguments: |
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72 | |
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73 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
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74 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
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75 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback |
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76 | to invoke everytime the filehandle becomes ready. |
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77 | |
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78 | Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
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79 | a socket you can have one r + one w, not any more (limitation comes from |
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80 | Tk - if you are sure you are not using Tk this limitation is gone). |
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81 | |
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82 | Filehandles will be kept alive, so as long as the watcher exists, the |
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83 | filehandle exists, too. |
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84 | |
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85 | Example: |
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86 | |
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87 | # wait for readability of STDIN, then read a line and disable the watcher |
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88 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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89 | chomp (my $input = <STDIN>); |
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90 | warn "read: $input\n"; |
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91 | undef $w; |
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92 | }); |
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93 | |
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94 | =head2 TIME WATCHERS |
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95 | |
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96 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
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97 | method with the following mandatory arguments: |
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98 | |
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99 | C<after> after how many seconds (fractions are supported) should the timer |
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100 | activate. C<cb> the callback to invoke. |
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101 | |
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102 | The timer callback will be invoked at most once: if you want a repeating |
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103 | timer you have to create a new watcher (this is a limitation by both Tk |
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104 | and Glib). |
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105 | |
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106 | Example: |
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107 | |
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108 | # fire an event after 7.7 seconds |
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109 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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110 | warn "timeout\n"; |
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111 | }); |
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112 | |
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113 | # to cancel the timer: |
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114 | undef $w |
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115 | |
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116 | =head2 CONDITION WATCHERS |
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117 | |
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118 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
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119 | method without any arguments. |
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120 | |
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121 | A condition watcher watches for a condition - precisely that the C<< |
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122 | ->broadcast >> method has been called. |
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123 | |
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124 | The watcher has only two methods: |
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125 | |
| 9 | =over 4 |
126 | =over 4 |
| 10 | |
127 | |
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128 | =item $cv->wait |
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129 | |
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130 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
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131 | called on c<$cv>, while servicing other watchers normally. |
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132 | |
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133 | Not all event models support a blocking wait - some die in that case, so |
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134 | if you are using this from a module, never require a blocking wait, but |
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135 | let the caller decide wether the call will block or not (for example, |
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136 | by coupling condition variables with some kind of request results and |
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137 | supporting callbacks so the caller knows that getting the result will not |
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138 | block, while still suppporting blockign waits if the caller so desires). |
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139 | |
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140 | You can only wait once on a condition - additional calls will return |
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141 | immediately. |
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142 | |
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143 | =item $cv->broadcast |
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144 | |
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145 | Flag the condition as ready - a running C<< ->wait >> and all further |
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146 | calls to C<wait> will return after this method has been called. If nobody |
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147 | is waiting the broadcast will be remembered.. |
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148 | |
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149 | Example: |
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150 | |
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151 | # wait till the result is ready |
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152 | my $result_ready = AnyEvent->condvar; |
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153 | |
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154 | # do something such as adding a timer |
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155 | # or socket watcher the calls $result_ready->broadcast |
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156 | # when the "result" is ready. |
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157 | |
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158 | $result_ready->wait; |
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159 | |
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160 | =back |
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161 | |
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162 | =head2 SIGNAL WATCHERS |
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163 | |
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164 | You can listen for signals using a signal watcher, C<signal> is the signal |
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165 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
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166 | together into one callback invocation, and callback invocation might or |
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167 | might not be asynchronous. |
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168 | |
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169 | These watchers might use C<%SIG>, so programs overwriting those signals |
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170 | directly will likely not work correctly. |
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171 | |
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172 | Example: exit on SIGINT |
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173 | |
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174 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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175 | |
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176 | =head2 CHILD PROCESS WATCHERS |
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177 | |
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178 | You can also listen for the status of a child process specified by the |
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179 | C<pid> argument. The watcher will only trigger once. This works by |
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180 | installing a signal handler for C<SIGCHLD>. |
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181 | |
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182 | Example: wait for pid 1333 |
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183 | |
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184 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
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185 | |
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186 | =head1 GLOBALS |
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187 | |
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188 | =over 4 |
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189 | |
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190 | =item $AnyEvent::MODEL |
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191 | |
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192 | Contains C<undef> until the first watcher is being created. Then it |
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193 | contains the event model that is being used, which is the name of the |
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194 | Perl class implementing the model. This class is usually one of the |
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195 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
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196 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
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197 | |
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198 | The known classes so far are: |
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199 | |
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200 | AnyEvent::Impl::Coro based on Coro::Event, best choise. |
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201 | AnyEvent::Impl::Event based on Event, also best choice :) |
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202 | AnyEvent::Impl::Glib based on Glib, second-best choice. |
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203 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
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204 | AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
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205 | |
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206 | =item AnyEvent::detect |
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207 | |
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208 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
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209 | necessary. You should only call this function right before you would have |
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210 | created an AnyEvent watcher anyway, that is, very late at runtime. |
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211 | |
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212 | =back |
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213 | |
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214 | =head1 WHAT TO DO IN A MODULE |
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215 | |
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216 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
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217 | freely, but you should not load a specific event module or rely on it. |
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218 | |
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219 | Be careful when you create watchers in the module body - Anyevent will |
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220 | decide which event module to use as soon as the first method is called, so |
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221 | by calling AnyEvent in your module body you force the user of your module |
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222 | to load the event module first. |
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223 | |
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224 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
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225 | |
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226 | There will always be a single main program - the only place that should |
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227 | dictate which event model to use. |
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228 | |
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229 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
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230 | do anything special and let AnyEvent decide which implementation to chose. |
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231 | |
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232 | If the main program relies on a specific event model (for example, in Gtk2 |
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233 | programs you have to rely on either Glib or Glib::Event), you should load |
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234 | it before loading AnyEvent or any module that uses it, generally, as early |
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235 | as possible. The reason is that modules might create watchers when they |
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236 | are loaded, and AnyEvent will decide on the event model to use as soon as |
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237 | it creates watchers, and it might chose the wrong one unless you load the |
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238 | correct one yourself. |
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239 | |
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240 | You can chose to use a rather inefficient pure-perl implementation by |
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241 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
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242 | generally better. |
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243 | |
| 11 | =cut |
244 | =cut |
| 12 | |
245 | |
| 13 | package AnyEvent; |
246 | package AnyEvent; |
| 14 | |
247 | |
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248 | no warnings; |
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249 | use strict; |
| 15 | use Carp; |
250 | use Carp; |
| 16 | |
251 | |
| 17 | $VERSION = 0.1; |
252 | our $VERSION = '2.52'; |
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253 | our $MODEL; |
| 18 | |
254 | |
| 19 | no warnings; |
255 | our $AUTOLOAD; |
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256 | our @ISA; |
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257 | |
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258 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
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259 | |
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260 | our @REGISTRY; |
| 20 | |
261 | |
| 21 | my @models = ( |
262 | my @models = ( |
| 22 | [Coro => Coro::Event::], |
263 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
| 23 | [Event => Event::], |
264 | [Event:: => AnyEvent::Impl::Event::], |
| 24 | [Glib => Glib::], |
265 | [Glib:: => AnyEvent::Impl::Glib::], |
| 25 | [Tk => Tk::], |
266 | [Tk:: => AnyEvent::Impl::Tk::], |
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267 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
| 26 | ); |
268 | ); |
| 27 | |
269 | |
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270 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
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271 | |
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272 | sub detect() { |
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273 | unless ($MODEL) { |
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274 | no strict 'refs'; |
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275 | |
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276 | # check for already loaded models |
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277 | for (@REGISTRY, @models) { |
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278 | my ($package, $model) = @$_; |
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279 | if (${"$package\::VERSION"} > 0) { |
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280 | if (eval "require $model") { |
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281 | $MODEL = $model; |
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282 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
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283 | last; |
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284 | } |
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285 | } |
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286 | } |
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287 | |
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288 | unless ($MODEL) { |
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289 | # try to load a model |
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290 | |
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291 | for (@REGISTRY, @models) { |
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292 | my ($package, $model) = @$_; |
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293 | if (eval "require $package" |
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294 | and ${"$package\::VERSION"} > 0 |
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295 | and eval "require $model") { |
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296 | $MODEL = $model; |
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297 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
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298 | last; |
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299 | } |
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300 | } |
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301 | |
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302 | $MODEL |
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303 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk."; |
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304 | } |
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305 | |
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306 | unshift @ISA, $MODEL; |
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307 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
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308 | } |
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309 | |
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310 | $MODEL |
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311 | } |
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312 | |
| 28 | sub AUTOLOAD { |
313 | sub AUTOLOAD { |
| 29 | $AUTOLOAD =~ s/.*://; |
314 | (my $func = $AUTOLOAD) =~ s/.*://; |
| 30 | |
315 | |
| 31 | for (@models) { |
316 | $method{$func} |
| 32 | my ($model, $package) = @$_; |
317 | or croak "$func: not a valid method for AnyEvent objects"; |
| 33 | if (defined ${"$package\::VERSION"}) { |
318 | |
| 34 | $EVENT = "AnyEvent::Impl::$model"; |
319 | detect unless $MODEL; |
| 35 | eval "require $EVENT"; die if $@; |
320 | |
| 36 | goto &{"$EVENT\::$AUTOLOAD"}; |
321 | my $class = shift; |
| 37 | } |
322 | $class->$func (@_); |
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323 | } |
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324 | |
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325 | package AnyEvent::Base; |
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326 | |
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327 | # default implementation for ->condvar, ->wait, ->broadcast |
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328 | |
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329 | sub condvar { |
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330 | bless \my $flag, "AnyEvent::Base::CondVar" |
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331 | } |
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332 | |
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333 | sub AnyEvent::Base::CondVar::broadcast { |
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334 | ${$_[0]}++; |
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335 | } |
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336 | |
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337 | sub AnyEvent::Base::CondVar::wait { |
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338 | AnyEvent->one_event while !${$_[0]}; |
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339 | } |
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340 | |
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341 | # default implementation for ->signal |
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342 | |
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343 | our %SIG_CB; |
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344 | |
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345 | sub signal { |
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346 | my (undef, %arg) = @_; |
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347 | |
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348 | my $signal = uc $arg{signal} |
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349 | or Carp::croak "required option 'signal' is missing"; |
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350 | |
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351 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
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352 | $SIG{$signal} ||= sub { |
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353 | $_->() for values %{ $SIG_CB{$signal} || {} }; |
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354 | }; |
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355 | |
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356 | bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
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357 | } |
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358 | |
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359 | sub AnyEvent::Base::Signal::DESTROY { |
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360 | my ($signal, $cb) = @{$_[0]}; |
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361 | |
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362 | delete $SIG_CB{$signal}{$cb}; |
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363 | |
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364 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
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365 | } |
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366 | |
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367 | # default implementation for ->child |
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368 | |
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369 | our %PID_CB; |
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370 | our $CHLD_W; |
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371 | our $PID_IDLE; |
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372 | our $WNOHANG; |
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373 | |
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374 | sub _child_wait { |
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375 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
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376 | $_->() for values %{ (delete $PID_CB{$pid}) || {} }; |
| 38 | } |
377 | } |
| 39 | |
378 | |
| 40 | for (@models) { |
379 | undef $PID_IDLE; |
| 41 | my ($model, $package) = @$_; |
380 | } |
| 42 | $EVENT = "AnyEvent::Impl::$model"; |
381 | |
| 43 | if (eval "require $EVENT") { |
382 | sub child { |
| 44 | goto &{"$EVENT\::$AUTOLOAD"}; |
383 | my (undef, %arg) = @_; |
| 45 | } |
384 | |
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385 | my $pid = uc $arg{pid} |
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386 | or Carp::croak "required option 'pid' is missing"; |
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387 | |
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388 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
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389 | |
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390 | unless ($WNOHANG) { |
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391 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
| 46 | } |
392 | } |
| 47 | |
393 | |
| 48 | die "No event module selected for AnyEvent and autodetect failed. Install any of these: Coro, Event, Glib or Tk."; |
394 | unless ($CHLD_W) { |
| 49 | } |
395 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait); |
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396 | # child could be a zombie already |
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397 | $PID_IDLE ||= AnyEvent->timer (after => 0, cb => \&_child_wait); |
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398 | } |
| 50 | |
399 | |
| 51 | 1; |
400 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
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401 | } |
| 52 | |
402 | |
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403 | sub AnyEvent::Base::Child::DESTROY { |
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404 | my ($pid, $cb) = @{$_[0]}; |
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405 | |
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406 | delete $PID_CB{$pid}{$cb}; |
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407 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
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408 | |
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409 | undef $CHLD_W unless keys %PID_CB; |
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410 | } |
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411 | |
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412 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
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413 | |
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414 | If you need to support another event library which isn't directly |
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415 | supported by AnyEvent, you can supply your own interface to it by |
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416 | pushing, before the first watcher gets created, the package name of |
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417 | the event module and the package name of the interface to use onto |
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418 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
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419 | AnyEvent. |
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420 | |
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421 | Example: |
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422 | |
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423 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
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424 | |
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425 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
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426 | package/class when it finds the C<urxvt> package/module is loaded. When |
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427 | AnyEvent is loaded and asked to find a suitable event model, it will |
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428 | first check for the presence of urxvt. |
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429 | |
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430 | The class should provide implementations for all watcher types (see |
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431 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
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432 | (Source code) and so on for actual examples, use C<perldoc -m |
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433 | AnyEvent::Impl::Glib> to see the sources). |
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434 | |
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435 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
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436 | uses the above line as-is. An interface isn't included in AnyEvent |
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437 | because it doesn't make sense outside the embedded interpreter inside |
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438 | I<rxvt-unicode>, and it is updated and maintained as part of the |
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439 | I<rxvt-unicode> distribution. |
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440 | |
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441 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
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442 | condition variables: code blocking while waiting for a condition will |
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443 | C<die>. This still works with most modules/usages, and blocking calls must |
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444 | not be in an interactive appliation, so it makes sense. |
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445 | |
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446 | =head1 ENVIRONMENT VARIABLES |
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447 | |
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448 | The following environment variables are used by this module: |
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449 | |
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450 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
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451 | model gets used. |
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452 | |
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453 | =head1 EXAMPLE |
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454 | |
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455 | The following program uses an io watcher to read data from stdin, a timer |
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456 | to display a message once per second, and a condvar to exit the program |
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457 | when the user enters quit: |
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458 | |
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459 | use AnyEvent; |
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460 | |
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461 | my $cv = AnyEvent->condvar; |
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462 | |
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463 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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464 | warn "io event <$_[0]>\n"; # will always output <r> |
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465 | chomp (my $input = <STDIN>); # read a line |
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466 | warn "read: $input\n"; # output what has been read |
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467 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
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468 | }); |
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469 | |
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470 | my $time_watcher; # can only be used once |
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471 | |
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|
472 | sub new_timer { |
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473 | $timer = AnyEvent->timer (after => 1, cb => sub { |
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474 | warn "timeout\n"; # print 'timeout' about every second |
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475 | &new_timer; # and restart the time |
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476 | }); |
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477 | } |
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478 | |
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479 | new_timer; # create first timer |
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480 | |
|
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481 | $cv->wait; # wait until user enters /^q/i |
|
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482 | |
|
|
483 | =head1 REAL-WORLD EXAMPLE |
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|
484 | |
|
|
485 | Consider the L<Net::FCP> module. It features (among others) the following |
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486 | API calls, which are to freenet what HTTP GET requests are to http: |
|
|
487 | |
|
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488 | my $data = $fcp->client_get ($url); # blocks |
|
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489 | |
|
|
490 | my $transaction = $fcp->txn_client_get ($url); # does not block |
|
|
491 | $transaction->cb ( sub { ... } ); # set optional result callback |
|
|
492 | my $data = $transaction->result; # possibly blocks |
|
|
493 | |
|
|
494 | The C<client_get> method works like C<LWP::Simple::get>: it requests the |
|
|
495 | given URL and waits till the data has arrived. It is defined to be: |
|
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496 | |
|
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497 | sub client_get { $_[0]->txn_client_get ($_[1])->result } |
|
|
498 | |
|
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499 | And in fact is automatically generated. This is the blocking API of |
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|
500 | L<Net::FCP>, and it works as simple as in any other, similar, module. |
|
|
501 | |
|
|
502 | More complicated is C<txn_client_get>: It only creates a transaction |
|
|
503 | (completion, result, ...) object and initiates the transaction. |
|
|
504 | |
|
|
505 | my $txn = bless { }, Net::FCP::Txn::; |
|
|
506 | |
|
|
507 | It also creates a condition variable that is used to signal the completion |
|
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508 | of the request: |
|
|
509 | |
|
|
510 | $txn->{finished} = AnyAvent->condvar; |
|
|
511 | |
|
|
512 | It then creates a socket in non-blocking mode. |
|
|
513 | |
|
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514 | socket $txn->{fh}, ...; |
|
|
515 | fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
|
|
516 | connect $txn->{fh}, ... |
|
|
517 | and !$!{EWOULDBLOCK} |
|
|
518 | and !$!{EINPROGRESS} |
|
|
519 | and Carp::croak "unable to connect: $!\n"; |
|
|
520 | |
|
|
521 | Then it creates a write-watcher which gets called whenever an error occurs |
|
|
522 | or the connection succeeds: |
|
|
523 | |
|
|
524 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
|
|
525 | |
|
|
526 | And returns this transaction object. The C<fh_ready_w> callback gets |
|
|
527 | called as soon as the event loop detects that the socket is ready for |
|
|
528 | writing. |
|
|
529 | |
|
|
530 | The C<fh_ready_w> method makes the socket blocking again, writes the |
|
|
531 | request data and replaces the watcher by a read watcher (waiting for reply |
|
|
532 | data). The actual code is more complicated, but that doesn't matter for |
|
|
533 | this example: |
|
|
534 | |
|
|
535 | fcntl $txn->{fh}, F_SETFL, 0; |
|
|
536 | syswrite $txn->{fh}, $txn->{request} |
|
|
537 | or die "connection or write error"; |
|
|
538 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
|
|
539 | |
|
|
540 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
|
|
541 | result and signals any possible waiters that the request ahs finished: |
|
|
542 | |
|
|
543 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
|
|
544 | |
|
|
545 | if (end-of-file or data complete) { |
|
|
546 | $txn->{result} = $txn->{buf}; |
|
|
547 | $txn->{finished}->broadcast; |
|
|
548 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
|
|
549 | } |
|
|
550 | |
|
|
551 | The C<result> method, finally, just waits for the finished signal (if the |
|
|
552 | request was already finished, it doesn't wait, of course, and returns the |
|
|
553 | data: |
|
|
554 | |
|
|
555 | $txn->{finished}->wait; |
|
|
556 | return $txn->{result}; |
|
|
557 | |
|
|
558 | The actual code goes further and collects all errors (C<die>s, exceptions) |
|
|
559 | that occured during request processing. The C<result> method detects |
|
|
560 | wether an exception as thrown (it is stored inside the $txn object) |
|
|
561 | and just throws the exception, which means connection errors and other |
|
|
562 | problems get reported tot he code that tries to use the result, not in a |
|
|
563 | random callback. |
|
|
564 | |
|
|
565 | All of this enables the following usage styles: |
|
|
566 | |
|
|
567 | 1. Blocking: |
|
|
568 | |
|
|
569 | my $data = $fcp->client_get ($url); |
|
|
570 | |
|
|
571 | 2. Blocking, but parallelizing: |
|
|
572 | |
|
|
573 | my @datas = map $_->result, |
|
|
574 | map $fcp->txn_client_get ($_), |
|
|
575 | @urls; |
|
|
576 | |
|
|
577 | Both blocking examples work without the module user having to know |
|
|
578 | anything about events. |
|
|
579 | |
|
|
580 | 3a. Event-based in a main program, using any support Event module: |
|
|
581 | |
|
|
582 | use Event; |
|
|
583 | |
|
|
584 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
585 | my $txn = shift; |
|
|
586 | my $data = $txn->result; |
|
|
587 | ... |
|
|
588 | }); |
|
|
589 | |
|
|
590 | Event::loop; |
|
|
591 | |
|
|
592 | 3b. The module user could use AnyEvent, too: |
|
|
593 | |
|
|
594 | use AnyEvent; |
|
|
595 | |
|
|
596 | my $quit = AnyEvent->condvar; |
|
|
597 | |
|
|
598 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
599 | ... |
|
|
600 | $quit->broadcast; |
|
|
601 | }); |
|
|
602 | |
|
|
603 | $quit->wait; |
|
|
604 | |
|
|
605 | =head1 SEE ALSO |
|
|
606 | |
|
|
607 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
|
|
608 | |
|
|
609 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
|
|
610 | |
|
|
611 | Nontrivial usage example: L<Net::FCP>. |
|
|
612 | |
|
|
613 | =head1 |
|
|
614 | |
|
|
615 | =cut |
|
|
616 | |
|
|
617 | 1 |
|
|
618 | |
