| 1 | =head1 NAME |
1 | =head1 NAME |
| 2 | |
2 | |
| 3 | AnyEvent::Fork - everything you wanted to use fork() for, but couldn't |
3 | AnyEvent::Fork - everything you wanted to use fork() for, but couldn't |
| 4 | |
4 | |
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5 | ATTENTION, this is a very early release, and very untested. Consider it a |
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6 | technology preview. |
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7 | |
| 5 | =head1 SYNOPSIS |
8 | =head1 SYNOPSIS |
| 6 | |
9 | |
| 7 | use AnyEvent::Fork; |
10 | use AnyEvent::Fork; |
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11 | |
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12 | ################################################################## |
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13 | # create a single new process, tell it to run your worker function |
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14 | |
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15 | AnyEvent::Fork |
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16 | ->new |
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17 | ->require ("MyModule") |
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18 | ->run ("MyModule::worker, sub { |
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19 | my ($master_filehandle) = @_; |
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20 | |
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21 | # now $master_filehandle is connected to the |
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22 | # $slave_filehandle in the new process. |
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23 | }); |
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24 | |
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25 | # MyModule::worker might look like this |
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26 | sub MyModule::worker { |
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27 | my ($slave_filehandle) = @_; |
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28 | |
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29 | # now $slave_filehandle is connected to the $master_filehandle |
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30 | # in the original prorcess. have fun! |
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31 | } |
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32 | |
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33 | ################################################################## |
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34 | # create a pool of server processes all accepting on the same socket |
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35 | |
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36 | # create listener socket |
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37 | my $listener = ...; |
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38 | |
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39 | # create a pool template, initialise it and give it the socket |
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40 | my $pool = AnyEvent::Fork |
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41 | ->new |
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42 | ->require ("Some::Stuff", "My::Server") |
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43 | ->send_fh ($listener); |
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44 | |
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45 | # now create 10 identical workers |
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46 | for my $id (1..10) { |
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47 | $pool |
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48 | ->fork |
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49 | ->send_arg ($id) |
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50 | ->run ("My::Server::run"); |
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51 | } |
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52 | |
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53 | # now do other things - maybe use the filehandle provided by run |
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54 | # to wait for the processes to die. or whatever. |
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55 | |
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56 | # My::Server::run might look like this |
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57 | sub My::Server::run { |
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58 | my ($slave, $listener, $id) = @_; |
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59 | |
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60 | close $slave; # we do not use the socket, so close it to save resources |
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61 | |
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62 | # we could go ballistic and use e.g. AnyEvent here, or IO::AIO, |
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63 | # or anything we usually couldn't do in a process forked normally. |
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64 | while (my $socket = $listener->accept) { |
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65 | # do sth. with new socket |
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66 | } |
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67 | } |
| 8 | |
68 | |
| 9 | =head1 DESCRIPTION |
69 | =head1 DESCRIPTION |
| 10 | |
70 | |
| 11 | This module allows you to create new processes, without actually forking |
71 | This module allows you to create new processes, without actually forking |
| 12 | them from your current process (avoiding the problems of forking), but |
72 | them from your current process (avoiding the problems of forking), but |
| … | |
… | |
| 111 | time, and the memory is not shared with anything else. |
171 | time, and the memory is not shared with anything else. |
| 112 | |
172 | |
| 113 | This is ideal for when you only need one extra process of a kind, with the |
173 | This is ideal for when you only need one extra process of a kind, with the |
| 114 | option of starting and stipping it on demand. |
174 | option of starting and stipping it on demand. |
| 115 | |
175 | |
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176 | Example: |
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177 | |
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178 | AnyEvent::Fork |
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179 | ->new |
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180 | ->require ("Some::Module") |
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181 | ->run ("Some::Module::run", sub { |
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182 | my ($fork_fh) = @_; |
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183 | }); |
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184 | |
| 116 | =item fork a new template process, load code, then fork processes off of |
185 | =item fork a new template process, load code, then fork processes off of |
| 117 | it and run the code |
186 | it and run the code |
| 118 | |
187 | |
| 119 | When you need to have a bunch of processes that all execute the same (or |
188 | When you need to have a bunch of processes that all execute the same (or |
| 120 | very similar) tasks, then a good way is to create a new template process |
189 | very similar) tasks, then a good way is to create a new template process |
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… | |
| 128 | The disadvantage of this approach is that you need to create a template |
197 | The disadvantage of this approach is that you need to create a template |
| 129 | process for the sole purpose of forking new processes from it, but if you |
198 | process for the sole purpose of forking new processes from it, but if you |
| 130 | only need a fixed number of proceses you can create them, and then destroy |
199 | only need a fixed number of proceses you can create them, and then destroy |
| 131 | the template process. |
200 | the template process. |
| 132 | |
201 | |
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202 | Example: |
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203 | |
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204 | my $template = AnyEvent::Fork->new->require ("Some::Module"); |
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205 | |
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206 | for (1..10) { |
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207 | $template->fork->run ("Some::Module::run", sub { |
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208 | my ($fork_fh) = @_; |
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209 | }); |
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210 | } |
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211 | |
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212 | # at this point, you can keep $template around to fork new processes |
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213 | # later, or you can destroy it, which causes it to vanish. |
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214 | |
| 133 | =item execute a new perl interpreter, load some code, run it |
215 | =item execute a new perl interpreter, load some code, run it |
| 134 | |
216 | |
| 135 | This is relatively slow, and doesn't allow you to share memory between |
217 | This is relatively slow, and doesn't allow you to share memory between |
| 136 | multiple processes. |
218 | multiple processes. |
| 137 | |
219 | |
| 138 | The only advantage is that you don't have to have a template process |
220 | The only advantage is that you don't have to have a template process |
| 139 | hanging around all the time to fork off some new processes, which might be |
221 | hanging around all the time to fork off some new processes, which might be |
| 140 | an advantage when there are long time spans where no extra processes are |
222 | an advantage when there are long time spans where no extra processes are |
| 141 | needed. |
223 | needed. |
| 142 | |
224 | |
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225 | Example: |
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226 | |
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227 | AnyEvent::Fork |
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228 | ->new_exec |
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229 | ->require ("Some::Module") |
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230 | ->run ("Some::Module::run", sub { |
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231 | my ($fork_fh) = @_; |
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232 | }); |
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233 | |
| 143 | =back |
234 | =back |
| 144 | |
235 | |
| 145 | =head1 FUNCTIONS |
236 | =head1 FUNCTIONS |
| 146 | |
237 | |
| 147 | =over 4 |
238 | =over 4 |
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| 177 | our $TEMPLATE; |
268 | our $TEMPLATE; |
| 178 | |
269 | |
| 179 | sub _cmd { |
270 | sub _cmd { |
| 180 | my $self = shift; |
271 | my $self = shift; |
| 181 | |
272 | |
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273 | #TODO: maybe append the packet to any existing string command already in the queue |
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274 | |
| 182 | # ideally, we would want to use "a (w/a)*" as format string, but perl versions |
275 | # ideally, we would want to use "a (w/a)*" as format string, but perl versions |
| 183 | # from at least 5.8.9 to 5.16.3 are all buggy and can't unpack it. |
276 | # from at least 5.8.9 to 5.16.3 are all buggy and can't unpack it. |
| 184 | push @{ $self->[2] }, pack "N/a", pack "(w/a)*", @_; |
277 | push @{ $self->[2] }, pack "N/a", pack "(w/a)*", @_; |
| 185 | |
278 | |
| 186 | $self->[3] ||= AE::io $self->[1], 1, sub { |
279 | $self->[3] ||= AE::io $self->[1], 1, sub { |
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280 | # send the next "thing" in the queue - either a reference to an fh, |
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281 | # or a plain string. |
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282 | |
| 187 | if (ref $self->[2][0]) { |
283 | if (ref $self->[2][0]) { |
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284 | # send fh |
| 188 | AnyEvent::Fork::Util::fd_send fileno $self->[1], fileno ${ $self->[2][0] } |
285 | AnyEvent::Fork::Util::fd_send fileno $self->[1], fileno ${ $self->[2][0] } |
| 189 | and shift @{ $self->[2] }; |
286 | and shift @{ $self->[2] }; |
| 190 | |
287 | |
| 191 | } else { |
288 | } else { |
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289 | # send string |
| 192 | my $len = syswrite $self->[1], $self->[2][0] |
290 | my $len = syswrite $self->[1], $self->[2][0] |
| 193 | or do { undef $self->[3]; die "AnyEvent::Fork: command write failure: $!" }; |
291 | or do { undef $self->[3]; die "AnyEvent::Fork: command write failure: $!" }; |
| 194 | |
292 | |
| 195 | substr $self->[2][0], 0, $len, ""; |
293 | substr $self->[2][0], 0, $len, ""; |
| 196 | shift @{ $self->[2] } unless length $self->[2][0]; |
294 | shift @{ $self->[2] } unless length $self->[2][0]; |
| 197 | } |
295 | } |
| 198 | |
296 | |
| 199 | unless (@{ $self->[2] }) { |
297 | unless (@{ $self->[2] }) { |
| 200 | undef $self->[3]; |
298 | undef $self->[3]; |
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299 | # invoke run callback |
| 201 | $self->[0]->($self->[1]) if $self->[0]; |
300 | $self->[0]->($self->[1]) if $self->[0]; |
| 202 | } |
301 | } |
| 203 | }; |
302 | }; |
| 204 | } |
303 | } |
| 205 | |
304 | |
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| 212 | undef, # run callback |
311 | undef, # run callback |
| 213 | $fh, |
312 | $fh, |
| 214 | [], # write queue - strings or fd's |
313 | [], # write queue - strings or fd's |
| 215 | undef, # AE watcher |
314 | undef, # AE watcher |
| 216 | ], $self; |
315 | ], $self; |
| 217 | |
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| 218 | # my ($a, $b) = AnyEvent::Util::portable_socketpair; |
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| 219 | |
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| 220 | # queue_cmd $template, "Iabc"; |
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| 221 | # push @{ $template->[2] }, \$b; |
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| 222 | |
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| 223 | # use Coro::AnyEvent; Coro::AnyEvent::sleep 1; |
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| 224 | # undef $b; |
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| 225 | # die "x" . <$a>; |
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| 226 | |
316 | |
| 227 | $self |
317 | $self |
| 228 | } |
318 | } |
| 229 | |
319 | |
| 230 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
320 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
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| 254 | object for further manipulation. |
344 | object for further manipulation. |
| 255 | |
345 | |
| 256 | The new process is forked from a template process that is kept around |
346 | The new process is forked from a template process that is kept around |
| 257 | for this purpose. When it doesn't exist yet, it is created by a call to |
347 | for this purpose. When it doesn't exist yet, it is created by a call to |
| 258 | C<new_exec> and kept around for future calls. |
348 | C<new_exec> and kept around for future calls. |
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349 | |
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350 | When the process object is destroyed, it will release the file handle |
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351 | that connects it with the new process. When the new process has not yet |
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352 | called C<run>, then the process will exit. Otherwise, what happens depends |
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353 | entirely on the code that is executed. |
| 259 | |
354 | |
| 260 | =cut |
355 | =cut |
| 261 | |
356 | |
| 262 | sub new { |
357 | sub new { |
| 263 | my $class = shift; |
358 | my $class = shift; |
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| 346 | ) or die "unable to spawn AnyEvent::Fork server: $!"; |
441 | ) or die "unable to spawn AnyEvent::Fork server: $!"; |
| 347 | |
442 | |
| 348 | $self->_new ($fh) |
443 | $self->_new ($fh) |
| 349 | } |
444 | } |
| 350 | |
445 | |
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446 | =item $proc = $proc->eval ($perlcode, @args) |
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447 | |
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448 | Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to |
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449 | the strings specified by C<@args>. |
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450 | |
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451 | This call is meant to do any custom initialisation that might be required |
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452 | (for example, the C<require> method uses it). It's not supposed to be used |
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453 | to completely take over the process, use C<run> for that. |
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454 | |
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455 | The code will usually be executed after this call returns, and there is no |
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456 | way to pass anything back to the calling process. Any evaluation errors |
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457 | will be reported to stderr and cause the process to exit. |
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458 | |
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459 | Returns the process object for easy chaining of method calls. |
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460 | |
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461 | =cut |
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462 | |
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463 | sub eval { |
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464 | my ($self, $code, @args) = @_; |
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465 | |
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466 | $self->_cmd (e => $code, @args); |
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467 | |
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468 | $self |
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469 | } |
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470 | |
| 351 | =item $proc = $proc->require ($module, ...) |
471 | =item $proc = $proc->require ($module, ...) |
| 352 | |
472 | |
| 353 | Tries to load the given modules into the process |
473 | Tries to load the given module(s) into the process |
| 354 | |
474 | |
| 355 | Returns the process object for easy chaining of method calls. |
475 | Returns the process object for easy chaining of method calls. |
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476 | |
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477 | =cut |
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478 | |
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479 | sub require { |
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480 | my ($self, @modules) = @_; |
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481 | |
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482 | s%::%/%g for @modules; |
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483 | $self->eval ('require "$_.pm" for @_', @modules); |
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484 | |
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485 | $self |
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486 | } |
| 356 | |
487 | |
| 357 | =item $proc = $proc->send_fh ($handle, ...) |
488 | =item $proc = $proc->send_fh ($handle, ...) |
| 358 | |
489 | |
| 359 | Send one or more file handles (I<not> file descriptors) to the process, |
490 | Send one or more file handles (I<not> file descriptors) to the process, |
| 360 | to prepare a call to C<run>. |
491 | to prepare a call to C<run>. |
| … | |
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| 364 | accomplished by simply not storing the file handles anywhere after passing |
495 | accomplished by simply not storing the file handles anywhere after passing |
| 365 | them to this method. |
496 | them to this method. |
| 366 | |
497 | |
| 367 | Returns the process object for easy chaining of method calls. |
498 | Returns the process object for easy chaining of method calls. |
| 368 | |
499 | |
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500 | Example: pass an fh to a process, and release it without closing. it will |
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501 | be closed automatically when it is no longer used. |
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502 | |
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503 | $proc->send_fh ($my_fh); |
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504 | undef $my_fh; # free the reference if you want, but DO NOT CLOSE IT |
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505 | |
| 369 | =cut |
506 | =cut |
| 370 | |
507 | |
| 371 | sub send_fh { |
508 | sub send_fh { |
| 372 | my ($self, @fh) = @_; |
509 | my ($self, @fh) = @_; |
| 373 | |
510 | |
| 374 | for my $fh (@fh) { |
511 | for my $fh (@fh) { |
| 375 | $self->_cmd ("h"); |
512 | $self->_cmd ("h"); |
| 376 | push @{ $self->[2] }, \$fh; |
513 | push @{ $self->[2] }, \$fh; |
| 377 | push @$self, $fh; # dire hack |
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| 378 | } |
514 | } |
| 379 | |
515 | |
| 380 | $self |
516 | $self |
| 381 | } |
517 | } |
| 382 | |
518 | |
| … | |
… | |
| 419 | otherwise, the socket can be a good indicator for the existance of the |
555 | otherwise, the socket can be a good indicator for the existance of the |
| 420 | process - if the other process exits, you get a readable event on it, |
556 | process - if the other process exits, you get a readable event on it, |
| 421 | because exiting the process closes the socket (if it didn't create any |
557 | because exiting the process closes the socket (if it didn't create any |
| 422 | children using fork). |
558 | children using fork). |
| 423 | |
559 | |
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560 | Example: create a template for a process pool, pass a few strings, some |
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561 | file handles, then fork, pass one more string, and run some code. |
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562 | |
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563 | my $pool = AnyEvent::Fork |
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564 | ->new |
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565 | ->send_arg ("str1", "str2") |
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566 | ->send_fh ($fh1, $fh2); |
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567 | |
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568 | for (1..2) { |
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569 | $pool |
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570 | ->fork |
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571 | ->send_arg ("str3") |
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572 | ->run ("Some::function", sub { |
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573 | my ($fh) = @_; |
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574 | |
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575 | # fh is nonblocking, but we trust that the OS can accept these |
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576 | # extra 3 octets anyway. |
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577 | syswrite $fh, "hi #$_\n"; |
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578 | |
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579 | # $fh is being closed here, as we don't store it anywhere |
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580 | }); |
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581 | } |
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582 | |
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583 | # Some::function might look like this - all parameters passed before fork |
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584 | # and after will be passed, in order, after the communications socket. |
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585 | sub Some::function { |
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586 | my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_; |
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587 | |
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588 | print scalar <$fh>; # prints "hi 1\n" and "hi 2\n" |
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589 | } |
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590 | |
| 424 | =cut |
591 | =cut |
| 425 | |
592 | |
| 426 | sub run { |
593 | sub run { |
| 427 | my ($self, $func, $cb) = @_; |
594 | my ($self, $func, $cb) = @_; |
| 428 | |
595 | |
| 429 | $self->[0] = $cb; |
596 | $self->[0] = $cb; |
| 430 | $self->_cmd ("r", $func); |
597 | $self->_cmd (r => $func); |
| 431 | } |
598 | } |
| 432 | |
599 | |
| 433 | =back |
600 | =back |
| 434 | |
601 | |
| 435 | =head1 PORTABILITY NOTES |
602 | =head1 PORTABILITY NOTES |
