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| 4 | |
4 | |
| 5 | Event, Coro, Glib, Tk - various supported event loops |
5 | Event, Coro, Glib, Tk - various supported event loops |
| 6 | |
6 | |
| 7 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
| 8 | |
8 | |
| 9 | use AnyEvent; |
9 | use AnyEvent; |
| 10 | |
10 | |
| 11 | my $w = AnyEvent->timer (fh => ..., poll => "[rw]+", cb => sub { |
11 | my $w = AnyEvent->io (fh => ..., poll => "[rw]+", cb => sub { |
| 12 | my ($poll_got) = @_; |
12 | my ($poll_got) = @_; |
| 13 | ... |
13 | ... |
| 14 | }); |
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 | |
| 15 | my $w = AnyEvent->io (after => $seconds, cb => sub { |
28 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
| 16 | ... |
29 | ... |
| 17 | }); |
30 | }); |
| 18 | |
31 | |
| 19 | # watchers get canceled whenever $w is destroyed |
32 | * io and time watchers get canceled whenever $w is destroyed, so keep a copy |
| 20 | # only one watcher per $fh and $poll type is allowed |
33 | |
| 21 | # (i.e. on a socket you cna have one r + one w or one rw |
34 | * timers can only be used once and must be recreated for repeated |
| 22 | # watcher, not any more. |
35 | operation (limitation by Glib and Tk). |
| 23 | # timers can only be used once |
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| 24 | |
36 | |
| 25 | my $w = AnyEvent->condvar; # kind of main loop replacement |
37 | my $w = AnyEvent->condvar; # kind of main loop replacement |
| 26 | # can only be used once |
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| 27 | $w->wait; # enters main loop till $condvar gets ->send |
38 | $w->wait; # enters main loop till $condvar gets ->broadcast |
| 28 | $w->broadcast; # wake up waiting and future wait's |
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. |
| 29 | |
45 | |
| 30 | =head1 DESCRIPTION |
46 | =head1 DESCRIPTION |
| 31 | |
47 | |
| 32 | L<AnyEvent> provides an identical interface to multiple event loops. This |
48 | L<AnyEvent> provides an identical interface to multiple event loops. This |
| 33 | allows module authors to utilizy an event loop without forcing module |
49 | allows module authors to utilizy an event loop without forcing module |
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| 52 | |
68 | |
| 53 | no warnings; |
69 | no warnings; |
| 54 | use strict 'vars'; |
70 | use strict 'vars'; |
| 55 | use Carp; |
71 | use Carp; |
| 56 | |
72 | |
| 57 | our $VERSION = 0.2; |
73 | our $VERSION = '0.4'; |
| 58 | our $MODEL; |
74 | our $MODEL; |
| 59 | |
75 | |
| 60 | our $AUTOLOAD; |
76 | our $AUTOLOAD; |
| 61 | our @ISA; |
77 | our @ISA; |
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78 | |
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79 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
| 62 | |
80 | |
| 63 | my @models = ( |
81 | my @models = ( |
| 64 | [Coro => Coro::Event::], |
82 | [Coro => Coro::Event::], |
| 65 | [Event => Event::], |
83 | [Event => Event::], |
| 66 | [Glib => Glib::], |
84 | [Glib => Glib::], |
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| 77 | |
95 | |
| 78 | unless ($MODEL) { |
96 | unless ($MODEL) { |
| 79 | # check for already loaded models |
97 | # check for already loaded models |
| 80 | for (@models) { |
98 | for (@models) { |
| 81 | my ($model, $package) = @$_; |
99 | my ($model, $package) = @$_; |
| 82 | if (scalar keys %{ *{"$package\::"} }) { |
100 | if (${"$package\::VERSION"} > 0) { |
| 83 | eval "require AnyEvent::Impl::$model" |
101 | eval "require AnyEvent::Impl::$model"; |
| 84 | or die; |
102 | warn "AnyEvent: found model '$model', using it.\n" if $MODEL && $verbose > 1; |
| 85 | |
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| 86 | last if $MODEL; |
103 | last if $MODEL; |
| 87 | } |
104 | } |
| 88 | } |
105 | } |
| 89 | |
106 | |
| 90 | unless ($MODEL) { |
107 | unless ($MODEL) { |
| 91 | # try to load a model |
108 | # try to load a model |
| 92 | |
109 | |
| 93 | for (@models) { |
110 | for (@models) { |
| 94 | my ($model, $package) = @$_; |
111 | my ($model, $package) = @$_; |
| 95 | eval "require AnyEvent::Impl::$model" |
112 | eval "require AnyEvent::Impl::$model"; |
| 96 | or die; |
113 | warn "AnyEvent: autprobed and loaded model '$model', using it.\n" if $MODEL && $verbose > 1; |
| 97 | |
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| 98 | last if $MODEL; |
114 | last if $MODEL; |
| 99 | } |
115 | } |
| 100 | |
116 | |
| 101 | $MODEL |
117 | $MODEL |
| 102 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk."; |
118 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk."; |
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| 108 | my $class = shift; |
124 | my $class = shift; |
| 109 | $class->$AUTOLOAD (@_); |
125 | $class->$AUTOLOAD (@_); |
| 110 | } |
126 | } |
| 111 | |
127 | |
| 112 | =back |
128 | =back |
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129 | |
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130 | =head1 ENVIRONMENT VARIABLES |
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131 | |
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132 | The following environment variables are used by this module: |
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133 | |
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134 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
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135 | model gets used. |
| 113 | |
136 | |
| 114 | =head1 EXAMPLE |
137 | =head1 EXAMPLE |
| 115 | |
138 | |
| 116 | The following program uses an io watcher to read data from stdin, a timer |
139 | The following program uses an io watcher to read data from stdin, a timer |
| 117 | to display a message once per second, and a condvar to exit the program |
140 | to display a message once per second, and a condvar to exit the program |
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| 139 | |
162 | |
| 140 | new_timer; # create first timer |
163 | new_timer; # create first timer |
| 141 | |
164 | |
| 142 | $cv->wait; # wait until user enters /^q/i |
165 | $cv->wait; # wait until user enters /^q/i |
| 143 | |
166 | |
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167 | =head1 REAL-WORLD EXAMPLE |
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168 | |
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169 | Consider the L<Net::FCP> module. It features (among others) the following |
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170 | API calls, which are to freenet what HTTP GET requests are to http: |
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171 | |
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172 | my $data = $fcp->client_get ($url); # blocks |
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173 | |
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174 | my $transaction = $fcp->txn_client_get ($url); # does not block |
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175 | $transaction->cb ( sub { ... } ); # set optional result callback |
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176 | my $data = $transaction->result; # possibly blocks |
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177 | |
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178 | The C<client_get> method works like C<LWP::Simple::get>: it requests the |
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179 | given URL and waits till the data has arrived. It is defined to be: |
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180 | |
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181 | sub client_get { $_[0]->txn_client_get ($_[1])->result } |
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182 | |
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183 | And in fact is automatically generated. This is the blocking API of |
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184 | L<Net::FCP>, and it works as simple as in any other, similar, module. |
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185 | |
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186 | More complicated is C<txn_client_get>: It only creates a transaction |
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187 | (completion, result, ...) object and initiates the transaction. |
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188 | |
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189 | my $txn = bless { }, Net::FCP::Txn::; |
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190 | |
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191 | It also creates a condition variable that is used to signal the completion |
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192 | of the request: |
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193 | |
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194 | $txn->{finished} = AnyAvent->condvar; |
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195 | |
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196 | It then creates a socket in non-blocking mode. |
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197 | |
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198 | socket $txn->{fh}, ...; |
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199 | fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
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200 | connect $txn->{fh}, ... |
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201 | and !$!{EWOULDBLOCK} |
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202 | and !$!{EINPROGRESS} |
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203 | and Carp::croak "unable to connect: $!\n"; |
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204 | |
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205 | Then it creates a write-watcher which gets called whenever an error occurs |
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206 | or the connection succeeds: |
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207 | |
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208 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
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209 | |
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210 | And returns this transaction object. The C<fh_ready_w> callback gets |
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211 | called as soon as the event loop detects that the socket is ready for |
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212 | writing. |
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213 | |
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214 | The C<fh_ready_w> method makes the socket blocking again, writes the |
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215 | request data and replaces the watcher by a read watcher (waiting for reply |
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216 | data). The actual code is more complicated, but that doesn't matter for |
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217 | this example: |
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218 | |
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219 | fcntl $txn->{fh}, F_SETFL, 0; |
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220 | syswrite $txn->{fh}, $txn->{request} |
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221 | or die "connection or write error"; |
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222 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
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223 | |
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224 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
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225 | result and signals any possible waiters that the request ahs finished: |
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226 | |
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227 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
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228 | |
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229 | if (end-of-file or data complete) { |
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230 | $txn->{result} = $txn->{buf}; |
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231 | $txn->{finished}->broadcast; |
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232 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
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233 | } |
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234 | |
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235 | The C<result> method, finally, just waits for the finished signal (if the |
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236 | request was already finished, it doesn't wait, of course, and returns the |
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237 | data: |
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238 | |
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239 | $txn->{finished}->wait; |
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240 | return $txn->{result}; |
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241 | |
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242 | The actual code goes further and collects all errors (C<die>s, exceptions) |
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243 | that occured during request processing. The C<result> method detects |
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244 | wether an exception as thrown (it is stored inside the $txn object) |
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245 | and just throws the exception, which means connection errors and other |
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246 | problems get reported tot he code that tries to use the result, not in a |
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247 | random callback. |
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248 | |
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249 | All of this enables the following usage styles: |
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250 | |
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251 | 1. Blocking: |
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252 | |
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253 | my $data = $fcp->client_get ($url); |
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254 | |
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255 | 2. Blocking, but parallelizing: |
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256 | |
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257 | my @datas = map $_->result, |
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258 | map $fcp->txn_client_get ($_), |
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259 | @urls; |
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260 | |
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261 | Both blocking examples work without the module user having to know |
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262 | anything about events. |
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263 | |
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264 | 3a. Event-based in a main program, using any support Event module: |
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265 | |
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266 | use Event; |
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267 | |
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268 | $fcp->txn_client_get ($url)->cb (sub { |
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269 | my $txn = shift; |
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270 | my $data = $txn->result; |
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271 | ... |
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272 | }); |
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273 | |
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274 | Event::loop; |
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275 | |
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276 | 3b. The module user could use AnyEvent, too: |
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277 | |
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278 | use AnyEvent; |
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279 | |
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280 | my $quit = AnyEvent->condvar; |
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281 | |
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282 | $fcp->txn_client_get ($url)->cb (sub { |
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283 | ... |
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284 | $quit->broadcast; |
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285 | }); |
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286 | |
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287 | $quit->wait; |
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288 | |
| 144 | =head1 SEE ALSO |
289 | =head1 SEE ALSO |
| 145 | |
290 | |
| 146 | L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>, |
291 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
| 147 | L<AnyEvent::Impl::Coro>, |
292 | |
| 148 | L<AnyEvent::Impl::Event>, |
293 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
| 149 | L<AnyEvent::Impl::Glib>, |
294 | |
| 150 | L<AnyEvent::Impl::Tk>. |
295 | Nontrivial usage example: L<Net::FCP>. |
| 151 | |
296 | |
| 152 | =head1 |
297 | =head1 |
| 153 | |
298 | |
| 154 | =cut |
299 | =cut |
| 155 | |
300 | |
