| … | |
… | |
| 2 | |
2 | |
| 3 | AnyEvent::Fork::RPC - simple RPC extension for AnyEvent::Fork |
3 | AnyEvent::Fork::RPC - simple RPC extension for AnyEvent::Fork |
| 4 | |
4 | |
| 5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
| 6 | |
6 | |
| 7 | use AnyEvent::Fork; |
|
|
| 8 | use AnyEvent::Fork::RPC; |
7 | use AnyEvent::Fork::RPC; |
|
|
8 | # use AnyEvent::Fork is not needed |
| 9 | |
9 | |
| 10 | my $rpc = AnyEvent::Fork |
10 | my $rpc = AnyEvent::Fork |
| 11 | ->new |
11 | ->new |
| 12 | ->require ("MyModule") |
12 | ->require ("MyModule") |
| 13 | ->AnyEvent::Fork::RPC::run ( |
13 | ->AnyEvent::Fork::RPC::run ( |
| … | |
… | |
| 34 | concurrently in the child, using AnyEvent. |
34 | concurrently in the child, using AnyEvent. |
| 35 | |
35 | |
| 36 | It also implements an asynchronous event mechanism from the child to the |
36 | It also implements an asynchronous event mechanism from the child to the |
| 37 | parent, that could be used for progress indications or other information. |
37 | parent, that could be used for progress indications or other information. |
| 38 | |
38 | |
|
|
39 | Loading this module also always loads L<AnyEvent::Fork>, so you can make a |
|
|
40 | separate C<use AnyEvent::Fork> if you wish, but you don't have to. |
|
|
41 | |
| 39 | =head1 EXAMPLES |
42 | =head1 EXAMPLES |
| 40 | |
43 | |
| 41 | =head2 Synchronous Backend |
44 | =head2 Example 1: Synchronous Backend |
| 42 | |
45 | |
| 43 | Here is a simple example that implements a backend that executes C<unlink> |
46 | Here is a simple example that implements a backend that executes C<unlink> |
| 44 | and C<rmdir> calls, and reports their status back. It also reports the |
47 | and C<rmdir> calls, and reports their status back. It also reports the |
| 45 | number of requests it has processed every three requests, which is clearly |
48 | number of requests it has processed every three requests, which is clearly |
| 46 | silly, but illustrates the use of events. |
49 | silly, but illustrates the use of events. |
| … | |
… | |
| 103 | dies with a fatal error - obviously, you must never let this happen :). |
106 | dies with a fatal error - obviously, you must never let this happen :). |
| 104 | |
107 | |
| 105 | Eventually it returns the status value true if the command was successful, |
108 | Eventually it returns the status value true if the command was successful, |
| 106 | or the status value 0 and the stringified error message. |
109 | or the status value 0 and the stringified error message. |
| 107 | |
110 | |
| 108 | On my system, running the first cdoe fragment with the given |
111 | On my system, running the first code fragment with the given |
| 109 | F<MyWorker.pm> in the current directory yields: |
112 | F<MyWorker.pm> in the current directory yields: |
| 110 | |
113 | |
| 111 | /tmp/somepath/1: No such file or directory |
114 | /tmp/somepath/1: No such file or directory |
| 112 | /tmp/somepath/2: No such file or directory |
115 | /tmp/somepath/2: No such file or directory |
| 113 | 3 requests handled |
116 | 3 requests handled |
| … | |
… | |
| 134 | |
137 | |
| 135 | And as a final remark, there is a fine module on CPAN that can |
138 | And as a final remark, there is a fine module on CPAN that can |
| 136 | asynchronously C<rmdir> and C<unlink> and a lot more, and more efficiently |
139 | asynchronously C<rmdir> and C<unlink> and a lot more, and more efficiently |
| 137 | than this example, namely L<IO::AIO>. |
140 | than this example, namely L<IO::AIO>. |
| 138 | |
141 | |
|
|
142 | =head3 Example 1a: the same with the asynchronous backend |
|
|
143 | |
|
|
144 | This example only shows what needs to be changed to use the async backend |
|
|
145 | instead. Doing this is not very useful, the purpose of this example is |
|
|
146 | to show the minimum amount of change that is required to go from the |
|
|
147 | synchronous to the asynchronous backend. |
|
|
148 | |
|
|
149 | To use the async backend in the previous example, you need to add the |
|
|
150 | C<async> parameter to the C<AnyEvent::Fork::RPC::run> call: |
|
|
151 | |
|
|
152 | ->AnyEvent::Fork::RPC::run ("MyWorker::run", |
|
|
153 | async => 1, |
|
|
154 | ... |
|
|
155 | |
|
|
156 | And since the function call protocol is now changed, you need to adopt |
|
|
157 | C<MyWorker::run> to the async API. |
|
|
158 | |
|
|
159 | First, you need to accept the extra initial C<$done> callback: |
|
|
160 | |
|
|
161 | sub run { |
|
|
162 | my ($done, $cmd, $path) = @_; |
|
|
163 | |
|
|
164 | And since a response is now generated when C<$done> is called, as opposed |
|
|
165 | to when the function returns, we need to call the C<$done> function with |
|
|
166 | the status: |
|
|
167 | |
|
|
168 | $done->($status or (0, "$!")); |
|
|
169 | |
|
|
170 | A few remarks are in order. First, it's quite pointless to use the async |
|
|
171 | backend for this example - but it I<is> possible. Second, you can call |
|
|
172 | C<$done> before or after returning from the function. Third, having both |
|
|
173 | returned from the function and having called the C<$done> callback, the |
|
|
174 | child process may exit at any time, so you should call C<$done> only when |
|
|
175 | you really I<are> done. |
|
|
176 | |
|
|
177 | =head2 Example 2: Asynchronous Backend |
|
|
178 | |
|
|
179 | #TODO |
|
|
180 | |
| 139 | =head1 PARENT PROCESS USAGE |
181 | =head1 PARENT PROCESS USAGE |
| 140 | |
182 | |
| 141 | This module exports nothing, and only implements a single function: |
183 | This module exports nothing, and only implements a single function: |
| 142 | |
184 | |
| 143 | =over 4 |
185 | =over 4 |
| … | |
… | |
| 150 | |
192 | |
| 151 | use Errno (); |
193 | use Errno (); |
| 152 | use Guard (); |
194 | use Guard (); |
| 153 | |
195 | |
| 154 | use AnyEvent; |
196 | use AnyEvent; |
| 155 | #use AnyEvent::Fork; |
197 | use AnyEvent::Fork; # we don't actually depend on it, this is for convenience |
| 156 | |
198 | |
| 157 | our $VERSION = 0.1; |
199 | our $VERSION = 0.1; |
| 158 | |
200 | |
| 159 | =item my $rpc = AnyEvent::Fork::RPC::run $fork, $function, [key => value...] |
201 | =item my $rpc = AnyEvent::Fork::RPC::run $fork, $function, [key => value...] |
| 160 | |
202 | |
| … | |
… | |
| 198 | |
240 | |
| 199 | Called when the C<$rpc> object has been destroyed and all requests have |
241 | Called when the C<$rpc> object has been destroyed and all requests have |
| 200 | been successfully handled. This is useful when you queue some requests and |
242 | been successfully handled. This is useful when you queue some requests and |
| 201 | want the child to go away after it has handled them. The problem is that |
243 | want the child to go away after it has handled them. The problem is that |
| 202 | the parent must not exit either until all requests have been handled, and |
244 | the parent must not exit either until all requests have been handled, and |
| 203 | this cna be accomplished by waiting for this callback. |
245 | this can be accomplished by waiting for this callback. |
| 204 | |
246 | |
| 205 | =item init => $function (default none) |
247 | =item init => $function (default none) |
| 206 | |
248 | |
| 207 | When specified (by name), this function is called in the child as the very |
249 | When specified (by name), this function is called in the child as the very |
| 208 | first thing when taking over the process, with all the arguments normally |
250 | first thing when taking over the process, with all the arguments normally |
| … | |
… | |
| 231 | If you want to pre-load the actual back-end modules to enable memory |
273 | If you want to pre-load the actual back-end modules to enable memory |
| 232 | sharing, then you should load C<AnyEvent::Fork::RPC::Sync> for |
274 | sharing, then you should load C<AnyEvent::Fork::RPC::Sync> for |
| 233 | synchronous, and C<AnyEvent::Fork::RPC::Async> for asynchronous mode. |
275 | synchronous, and C<AnyEvent::Fork::RPC::Async> for asynchronous mode. |
| 234 | |
276 | |
| 235 | If you use a template process and want to fork both sync and async |
277 | If you use a template process and want to fork both sync and async |
| 236 | children, then it is permissible to laod both modules. |
278 | children, then it is permissible to load both modules. |
| 237 | |
279 | |
| 238 | =item serialiser => $string (default: '(sub { pack "(w/a*)*", @_ }, sub { unpack "(w/a*)*", shift })') |
280 | =item serialiser => $string (default: '(sub { pack "(w/a*)*", @_ }, sub { unpack "(w/a*)*", shift })') |
| 239 | |
281 | |
| 240 | All arguments, result data and event data have to be serialised to be |
282 | All arguments, result data and event data have to be serialised to be |
| 241 | transferred between the processes. For this, they have to be frozen and |
283 | transferred between the processes. For this, they have to be frozen and |
| … | |
… | |
| 253 | If you need an external module for serialisation, then you can either |
295 | If you need an external module for serialisation, then you can either |
| 254 | pre-load it into your L<AnyEvent::Fork> process, or you can add a C<use> |
296 | pre-load it into your L<AnyEvent::Fork> process, or you can add a C<use> |
| 255 | or C<require> statement into the serialiser string. Or both. |
297 | or C<require> statement into the serialiser string. Or both. |
| 256 | |
298 | |
| 257 | =back |
299 | =back |
|
|
300 | |
|
|
301 | See the examples section earlier in this document for some actual |
|
|
302 | examples. |
| 258 | |
303 | |
| 259 | =cut |
304 | =cut |
| 260 | |
305 | |
| 261 | our $STRING_SERIALISER = '(sub { pack "(w/a*)*", @_ }, sub { unpack "(w/a*)*", shift })'; |
306 | our $STRING_SERIALISER = '(sub { pack "(w/a*)*", @_ }, sub { unpack "(w/a*)*", shift })'; |
| 262 | |
307 | |
| … | |
… | |
| 276 | # default for on_event is to raise an error |
321 | # default for on_event is to raise an error |
| 277 | $on_event ||= sub { $on_error->("event received, but no on_event handler") }; |
322 | $on_event ||= sub { $on_error->("event received, but no on_event handler") }; |
| 278 | |
323 | |
| 279 | my ($f, $t) = eval $serialiser; die $@ if $@; |
324 | my ($f, $t) = eval $serialiser; die $@ if $@; |
| 280 | |
325 | |
| 281 | my (@rcb, $fh, $shutdown, $wbuf, $ww, $rw); |
326 | my (@rcb, %rcb, $fh, $shutdown, $wbuf, $ww); |
| 282 | my ($rlen, $rbuf) = 512 - 16; |
327 | my ($rlen, $rbuf, $rw) = 512 - 16; |
| 283 | |
328 | |
| 284 | my $wcb = sub { |
329 | my $wcb = sub { |
| 285 | my $len = syswrite $fh, $wbuf; |
330 | my $len = syswrite $fh, $wbuf; |
| 286 | |
331 | |
| 287 | if (!defined $len) { |
332 | unless (defined $len) { |
| 288 | if ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) { |
333 | if ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) { |
| 289 | undef $rw; undef $ww; # it ends here |
334 | undef $rw; undef $ww; # it ends here |
| 290 | $on_error->("$!"); |
335 | $on_error->("$!"); |
| 291 | } |
336 | } |
| 292 | } |
337 | } |
| … | |
… | |
| 303 | |
348 | |
| 304 | $self->require ($module) |
349 | $self->require ($module) |
| 305 | ->send_arg ($function, $arg{init}, $serialiser) |
350 | ->send_arg ($function, $arg{init}, $serialiser) |
| 306 | ->run ("$module\::run", sub { |
351 | ->run ("$module\::run", sub { |
| 307 | $fh = shift; |
352 | $fh = shift; |
|
|
353 | |
|
|
354 | my ($id, $len); |
| 308 | $rw = AE::io $fh, 0, sub { |
355 | $rw = AE::io $fh, 0, sub { |
| 309 | $rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf; |
356 | $rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf; |
| 310 | my $len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf; |
357 | $len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf; |
| 311 | |
358 | |
| 312 | if ($len) { |
359 | if ($len) { |
| 313 | while (5 <= length $rbuf) { |
360 | while (8 <= length $rbuf) { |
| 314 | $len = unpack "L", $rbuf; |
361 | ($id, $len) = unpack "LL", $rbuf; |
| 315 | 4 + $len <= length $rbuf |
362 | 8 + $len <= length $rbuf |
| 316 | or last; |
363 | or last; |
| 317 | |
364 | |
| 318 | my @r = $t->(substr $rbuf, 4, $len); |
365 | my @r = $t->(substr $rbuf, 8, $len); |
| 319 | substr $rbuf, 0, $len + 4, ""; |
366 | substr $rbuf, 0, 8 + $len, ""; |
|
|
367 | |
|
|
368 | if ($id) { |
|
|
369 | if (@rcb) { |
|
|
370 | (shift @rcb)->(@r); |
|
|
371 | } elsif (my $cb = delete $rcb{$id}) { |
|
|
372 | $cb->(@r); |
|
|
373 | } else { |
|
|
374 | undef $rw; undef $ww; |
|
|
375 | $on_error->("unexpected data from child"); |
| 320 | |
376 | } |
| 321 | if (pop @r) { |
377 | } else { |
| 322 | $on_event->(@r); |
378 | $on_event->(@r); |
| 323 | } elsif (@rcb) { |
|
|
| 324 | (shift @rcb)->(@r); |
|
|
| 325 | } else { |
|
|
| 326 | undef $rw; undef $ww; |
|
|
| 327 | $on_error->("unexpected data from child"); |
|
|
| 328 | } |
379 | } |
| 329 | } |
380 | } |
| 330 | } elsif (defined $len) { |
381 | } elsif (defined $len) { |
| 331 | undef $rw; undef $ww; # it ends here |
382 | undef $rw; undef $ww; # it ends here |
| 332 | |
383 | |
| 333 | if (@rcb) { |
384 | if (@rcb || %rcb) { |
|
|
385 | use Data::Dump;ddx[\@rcb,\%rcb];#d# |
| 334 | $on_error->("unexpected eof"); |
386 | $on_error->("unexpected eof"); |
| 335 | } else { |
387 | } else { |
| 336 | $on_destroy->(); |
388 | $on_destroy->(); |
| 337 | } |
389 | } |
| 338 | } elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) { |
390 | } elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) { |
| … | |
… | |
| 347 | my $guard = Guard::guard { |
399 | my $guard = Guard::guard { |
| 348 | $shutdown = 1; |
400 | $shutdown = 1; |
| 349 | $ww ||= $fh && AE::io $fh, 1, $wcb; |
401 | $ww ||= $fh && AE::io $fh, 1, $wcb; |
| 350 | }; |
402 | }; |
| 351 | |
403 | |
|
|
404 | my $id; |
|
|
405 | |
|
|
406 | $arg{async} |
| 352 | sub { |
407 | ? sub { |
| 353 | push @rcb, pop; |
408 | $id = ($id == 0xffffffff ? 0 : $id) + 1; |
|
|
409 | $id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops |
| 354 | |
410 | |
|
|
411 | $rcb{$id} = pop; |
|
|
412 | |
| 355 | $guard; # keep it alive |
413 | $guard; # keep it alive |
| 356 | |
414 | |
| 357 | $wbuf .= pack "L/a*", &$f; |
415 | $wbuf .= pack "LL/a*", $id, &$f; |
| 358 | $ww ||= $fh && AE::io $fh, 1, $wcb; |
416 | $ww ||= $fh && AE::io $fh, 1, $wcb; |
| 359 | } |
417 | } |
|
|
418 | : sub { |
|
|
419 | push @rcb, pop; |
|
|
420 | |
|
|
421 | $guard; # keep it alive |
|
|
422 | |
|
|
423 | $wbuf .= pack "L/a*", &$f; |
|
|
424 | $ww ||= $fh && AE::io $fh, 1, $wcb; |
|
|
425 | } |
| 360 | } |
426 | } |
| 361 | |
427 | |
| 362 | =item $rpc->(..., $cb->(...)) |
428 | =item $rpc->(..., $cb->(...)) |
| 363 | |
429 | |
| 364 | The RPC object returned by C<AnyEvent::Fork::RPC::run> is actually a code |
430 | The RPC object returned by C<AnyEvent::Fork::RPC::run> is actually a code |
| … | |
… | |
| 379 | |
445 | |
| 380 | The other thing that can be done with the RPC object is to destroy it. In |
446 | The other thing that can be done with the RPC object is to destroy it. In |
| 381 | this case, the child process will execute all remaining RPC calls, report |
447 | this case, the child process will execute all remaining RPC calls, report |
| 382 | their results, and then exit. |
448 | their results, and then exit. |
| 383 | |
449 | |
|
|
450 | See the examples section earlier in this document for some actual |
|
|
451 | examples. |
|
|
452 | |
| 384 | =back |
453 | =back |
| 385 | |
454 | |
| 386 | =head1 CHILD PROCESS USAGE |
455 | =head1 CHILD PROCESS USAGE |
| 387 | |
456 | |
| 388 | The following function is not available in this module. They are only |
457 | The following function is not available in this module. They are only |
| … | |
… | |
| 396 | |
465 | |
| 397 | Send an event to the parent. Events are a bit like RPC calls made by the |
466 | Send an event to the parent. Events are a bit like RPC calls made by the |
| 398 | child process to the parent, except that there is no notion of return |
467 | child process to the parent, except that there is no notion of return |
| 399 | values. |
468 | values. |
| 400 | |
469 | |
|
|
470 | See the examples section earlier in this document for some actual |
|
|
471 | examples. |
|
|
472 | |
| 401 | =back |
473 | =back |
| 402 | |
474 | |
| 403 | =head1 SEE ALSO |
475 | =head1 SEE ALSO |
| 404 | |
476 | |
| 405 | L<AnyEvent::Fork> (to create the processes in the first place), |
477 | L<AnyEvent::Fork> (to create the processes in the first place), |
