| 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 - 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 $w = AnyEvent->io (fh => ..., poll => "[rw]+", cb => sub { |
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12 | my ($poll_got) = @_; |
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13 | ... |
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14 | }); |
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15 | |
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16 | * only one io watcher per $fh and $poll type is allowed (i.e. on a socket |
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17 | you can have one r + one w or one rw watcher, not any more (limitation by |
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18 | Tk). |
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19 | |
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20 | * the C<$poll_got> passed to the handler needs to be checked by looking |
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21 | for single characters (e.g. with a regex), as it can contain more event |
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22 | types than were requested (e.g. a 'w' watcher might generate 'rw' events, |
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23 | limitation by Glib). |
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24 | |
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25 | * AnyEvent will keep filehandles alive, so as long as the watcher exists, |
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26 | the filehandle exists. |
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27 | |
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28 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
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29 | ... |
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30 | }); |
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31 | |
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32 | * io and time watchers get canceled whenever $w is destroyed, so keep a copy |
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33 | |
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34 | * timers can only be used once and must be recreated for repeated |
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35 | operation (limitation by Glib and Tk). |
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36 | |
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37 | my $w = AnyEvent->condvar; # kind of main loop replacement |
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38 | $w->wait; # enters main loop till $condvar gets ->broadcast |
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39 | $w->broadcast; # wake up current and all future wait's |
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40 | |
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41 | * condvars are used to give blocking behaviour when neccessary. Create |
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42 | a condvar for any "request" or "event" your module might create, C<< |
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43 | ->broadcast >> it when the event happens and provide a function that calls |
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44 | C<< ->wait >> for it. See the examples below. |
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45 | |
| 7 | =head1 DESCRIPTION |
46 | =head1 DESCRIPTION |
| 8 | |
47 | |
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48 | L<AnyEvent> provides an identical interface to multiple event loops. This |
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49 | allows module authors to utilizy an event loop without forcing module |
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50 | users to use the same event loop (as only a single event loop can coexist |
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51 | peacefully at any one time). |
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52 | |
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53 | The interface itself is vaguely similar but not identical to the Event |
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54 | module. |
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55 | |
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56 | On the first call of any method, the module tries to detect the currently |
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57 | loaded event loop by probing wether any of the following modules is |
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58 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
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59 | used. If none is found, the module tries to load these modules in the |
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60 | order given. The first one that could be successfully loaded will be |
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61 | used. If still none could be found, it will issue an error. |
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62 | |
| 9 | =over 4 |
63 | =over 4 |
| 10 | |
64 | |
| 11 | =cut |
65 | =cut |
| 12 | |
66 | |
| 13 | package AnyEvent; |
67 | package AnyEvent; |
| 14 | |
68 | |
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69 | no warnings; |
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70 | use strict 'vars'; |
| 15 | use Carp; |
71 | use Carp; |
| 16 | |
72 | |
| 17 | $VERSION = 0.1; |
73 | our $VERSION = '1.02'; |
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74 | our $MODEL; |
| 18 | |
75 | |
| 19 | no warnings; |
76 | our $AUTOLOAD; |
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77 | our @ISA; |
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78 | |
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79 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
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80 | |
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81 | our @REGISTRY; |
| 20 | |
82 | |
| 21 | my @models = ( |
83 | my @models = ( |
| 22 | [Coro => Coro::Event::], |
84 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
| 23 | [Event => Event::], |
85 | [Event:: => AnyEvent::Impl::Event::], |
| 24 | [Glib => Glib::], |
86 | [Glib:: => AnyEvent::Impl::Glib::], |
| 25 | [Tk => Tk::], |
87 | [Tk:: => AnyEvent::Impl::Tk::], |
| 26 | ); |
88 | ); |
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89 | |
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90 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY); |
| 27 | |
91 | |
| 28 | sub AUTOLOAD { |
92 | sub AUTOLOAD { |
| 29 | $AUTOLOAD =~ s/.*://; |
93 | $AUTOLOAD =~ s/.*://; |
| 30 | |
94 | |
| 31 | for (@models) { |
95 | $method{$AUTOLOAD} |
| 32 | my ($model, $package) = @$_; |
96 | or croak "$AUTOLOAD: not a valid method for AnyEvent objects"; |
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97 | |
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98 | unless ($MODEL) { |
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99 | # check for already loaded models |
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100 | for (@REGISTRY, @models) { |
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101 | my ($package, $model) = @$_; |
| 33 | if (defined ${"$package\::VERSION"}) { |
102 | if (${"$package\::VERSION"} > 0) { |
| 34 | $EVENT = "AnyEvent::Impl::$model"; |
103 | if (eval "require $model") { |
| 35 | eval "require $EVENT"; die if $@; |
104 | $MODEL = $model; |
| 36 | goto &{"$EVENT\::$AUTOLOAD"}; |
105 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
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106 | last; |
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107 | } |
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108 | } |
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109 | } |
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110 | |
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111 | unless ($MODEL) { |
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112 | # try to load a model |
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113 | |
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114 | for (@REGISTRY, @models) { |
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115 | my ($package, $model) = @$_; |
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116 | if (eval "require $model") { |
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117 | $MODEL = $model; |
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118 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
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119 | last; |
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120 | } |
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121 | } |
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122 | |
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123 | $MODEL |
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124 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk."; |
| 37 | } |
125 | } |
| 38 | } |
126 | } |
| 39 | |
127 | |
| 40 | for (@models) { |
128 | @ISA = $MODEL; |
| 41 | my ($model, $package) = @$_; |
129 | |
| 42 | $EVENT = "AnyEvent::Impl::$model"; |
130 | my $class = shift; |
| 43 | if (eval "require $EVENT") { |
131 | $class->$AUTOLOAD (@_); |
| 44 | goto &{"$EVENT\::$AUTOLOAD"}; |
132 | } |
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133 | |
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134 | =back |
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135 | |
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136 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
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137 | |
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138 | If you need to support another event library which isn't directly |
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139 | supported by AnyEvent, you can supply your own interface to it by |
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140 | pushing, before the first watch gets created, the package name of |
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141 | the event module and the package name of the interface to use onto |
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142 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
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143 | AnyEvent. |
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144 | |
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145 | Example: |
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146 | |
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147 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
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148 | |
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149 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> module |
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150 | when it finds the C<urxvt> module is loaded. When AnyEvent is loaded and |
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151 | requested to find a suitable event model, it will first check for the |
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152 | urxvt module. |
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153 | |
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154 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) uses |
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155 | the above line exactly. An interface isn't included in AnyEvent |
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156 | because it doesn't make sense outside the embedded interpreter inside |
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157 | I<rxvt-unicode>, and it is updated and maintained as part of the |
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158 | I<rxvt-unicode> distribution. |
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159 | |
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160 | =head1 ENVIRONMENT VARIABLES |
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161 | |
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162 | The following environment variables are used by this module: |
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163 | |
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164 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
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165 | model gets used. |
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166 | |
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167 | =head1 EXAMPLE |
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168 | |
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169 | The following program uses an io watcher to read data from stdin, a timer |
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170 | to display a message once per second, and a condvar to exit the program |
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171 | when the user enters quit: |
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172 | |
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173 | use AnyEvent; |
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174 | |
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175 | my $cv = AnyEvent->condvar; |
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176 | |
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177 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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178 | warn "io event <$_[0]>\n"; # will always output <r> |
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179 | chomp (my $input = <STDIN>); # read a line |
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180 | warn "read: $input\n"; # output what has been read |
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181 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
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182 | }); |
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183 | |
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184 | my $time_watcher; # can only be used once |
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185 | |
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186 | sub new_timer { |
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187 | $timer = AnyEvent->timer (after => 1, cb => sub { |
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188 | warn "timeout\n"; # print 'timeout' about every second |
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189 | &new_timer; # and restart the time |
| 45 | } |
190 | }); |
| 46 | } |
191 | } |
| 47 | |
192 | |
| 48 | die "No event module selected for AnyEvent and autodetect failed. Install any of these: Coro, Event, Glib or Tk."; |
193 | new_timer; # create first timer |
| 49 | } |
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| 50 | |
194 | |
| 51 | 1; |
195 | $cv->wait; # wait until user enters /^q/i |
| 52 | |
196 | |
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197 | =head1 REAL-WORLD EXAMPLE |
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198 | |
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199 | Consider the L<Net::FCP> module. It features (among others) the following |
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200 | API calls, which are to freenet what HTTP GET requests are to http: |
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201 | |
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202 | my $data = $fcp->client_get ($url); # blocks |
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203 | |
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204 | my $transaction = $fcp->txn_client_get ($url); # does not block |
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205 | $transaction->cb ( sub { ... } ); # set optional result callback |
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206 | my $data = $transaction->result; # possibly blocks |
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207 | |
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208 | The C<client_get> method works like C<LWP::Simple::get>: it requests the |
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209 | given URL and waits till the data has arrived. It is defined to be: |
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210 | |
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211 | sub client_get { $_[0]->txn_client_get ($_[1])->result } |
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212 | |
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213 | And in fact is automatically generated. This is the blocking API of |
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214 | L<Net::FCP>, and it works as simple as in any other, similar, module. |
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215 | |
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216 | More complicated is C<txn_client_get>: It only creates a transaction |
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217 | (completion, result, ...) object and initiates the transaction. |
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218 | |
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219 | my $txn = bless { }, Net::FCP::Txn::; |
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220 | |
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221 | It also creates a condition variable that is used to signal the completion |
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222 | of the request: |
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223 | |
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224 | $txn->{finished} = AnyAvent->condvar; |
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225 | |
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226 | It then creates a socket in non-blocking mode. |
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227 | |
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228 | socket $txn->{fh}, ...; |
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229 | fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
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230 | connect $txn->{fh}, ... |
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231 | and !$!{EWOULDBLOCK} |
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232 | and !$!{EINPROGRESS} |
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233 | and Carp::croak "unable to connect: $!\n"; |
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234 | |
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235 | Then it creates a write-watcher which gets called whenever an error occurs |
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236 | or the connection succeeds: |
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237 | |
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238 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
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239 | |
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240 | And returns this transaction object. The C<fh_ready_w> callback gets |
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241 | called as soon as the event loop detects that the socket is ready for |
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242 | writing. |
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243 | |
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244 | The C<fh_ready_w> method makes the socket blocking again, writes the |
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245 | request data and replaces the watcher by a read watcher (waiting for reply |
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246 | data). The actual code is more complicated, but that doesn't matter for |
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247 | this example: |
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248 | |
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249 | fcntl $txn->{fh}, F_SETFL, 0; |
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250 | syswrite $txn->{fh}, $txn->{request} |
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251 | or die "connection or write error"; |
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252 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
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253 | |
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254 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
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255 | result and signals any possible waiters that the request ahs finished: |
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256 | |
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257 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
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258 | |
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259 | if (end-of-file or data complete) { |
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260 | $txn->{result} = $txn->{buf}; |
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261 | $txn->{finished}->broadcast; |
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262 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
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263 | } |
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264 | |
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265 | The C<result> method, finally, just waits for the finished signal (if the |
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266 | request was already finished, it doesn't wait, of course, and returns the |
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267 | data: |
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268 | |
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269 | $txn->{finished}->wait; |
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270 | return $txn->{result}; |
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271 | |
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272 | The actual code goes further and collects all errors (C<die>s, exceptions) |
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273 | that occured during request processing. The C<result> method detects |
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274 | wether an exception as thrown (it is stored inside the $txn object) |
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275 | and just throws the exception, which means connection errors and other |
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276 | problems get reported tot he code that tries to use the result, not in a |
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277 | random callback. |
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278 | |
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279 | All of this enables the following usage styles: |
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280 | |
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281 | 1. Blocking: |
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282 | |
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283 | my $data = $fcp->client_get ($url); |
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284 | |
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285 | 2. Blocking, but parallelizing: |
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286 | |
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287 | my @datas = map $_->result, |
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288 | map $fcp->txn_client_get ($_), |
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289 | @urls; |
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290 | |
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291 | Both blocking examples work without the module user having to know |
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292 | anything about events. |
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293 | |
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294 | 3a. Event-based in a main program, using any support Event module: |
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295 | |
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296 | use Event; |
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297 | |
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298 | $fcp->txn_client_get ($url)->cb (sub { |
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299 | my $txn = shift; |
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300 | my $data = $txn->result; |
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301 | ... |
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302 | }); |
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303 | |
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304 | Event::loop; |
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305 | |
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306 | 3b. The module user could use AnyEvent, too: |
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307 | |
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308 | use AnyEvent; |
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309 | |
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310 | my $quit = AnyEvent->condvar; |
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311 | |
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312 | $fcp->txn_client_get ($url)->cb (sub { |
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313 | ... |
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314 | $quit->broadcast; |
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315 | }); |
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316 | |
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317 | $quit->wait; |
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318 | |
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319 | =head1 SEE ALSO |
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320 | |
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321 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
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322 | |
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323 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
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324 | |
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325 | Nontrivial usage example: L<Net::FCP>. |
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326 | |
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327 | =head1 |
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328 | |
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329 | =cut |
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330 | |
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331 | 1 |
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332 | |
