[ViewVC] Diff of: cvs/cvsroot/AnyEvent-MP/MP.pm

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs.
Revision 1.42 by root, Sun Aug 9 00:41:49 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# ports are message endpoints
		16
		17	# sending messages
13	snd $port, type => data...;	18	snd $port, type => data...;
		19	snd $port, @msg;
		20	snd @msg_with_first_element_being_a_port;
14		21
15	$SELF # receiving/own port id in rcv callbacks	22	# miniports
		23	my $miniport = port { my @msg = @_; 0 };
16		24
		25	# full ports
		26	my $port = port;
17	rcv $port, smartmatch => $cb->($port, @msg);	27	rcv $port, smartmatch => $cb->(@msg);
18
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	29	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;	30
		31	# remote ports
		32	my $port = spawn $node, $initfunc, @initdata;
23		33
24	# more, smarter, matches (_any_ is exported by this module)	34	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	35	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
		37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
27		42
28	=head1 DESCRIPTION	43	=head1 DESCRIPTION
29		44
30	This module (-family) implements a simple message passing framework.	45	This module (-family) implements a simple message passing framework.
31		46
…		…
104		119
105	our $VERSION = '0.1';	120	our $VERSION = '0.1';
106	our @EXPORT = qw(	121	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	122	NODE $NODE *SELF node_of _any_
108	resolve_node initialise_node	123	resolve_node initialise_node
109	snd rcv mon kil reg psub	124	snd rcv mon kil reg psub spawn
110	port	125	port
111	);	126	);
112		127
113	our $SELF;	128	our $SELF;
114		129
…		…
297	$port	312	$port
298	}	313	}
299		314
300	=item reg $port, $name	315	=item reg $port, $name
301		316
302	Registers the given port under the name C<$name>. If the name already	317	=item reg $name
303	exists it is replaced.	318
		319	Registers the given port (or C<$SELF><<< if missing) under the name
		320	C<$name>. If the name already exists it is replaced.
304		321
305	A port can only be registered under one well known name.	322	A port can only be registered under one well known name.
306		323
307	A port automatically becomes unregistered when it is killed.	324	A port automatically becomes unregistered when it is killed.
308		325
309	=cut	326	=cut
310		327
311	sub reg(@) {	328	sub reg(@) {
312	my ($port, $name) = @_;	329	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
313		330
314	$REG{$name} = $port;	331	$REG{$_[0]} = $port;
315	}	332	}
316		333
317	=item rcv $port, $callback->(@msg)	334	=item rcv $port, $callback->(@msg)
318		335
319	Replaces the callback on the specified miniport (after converting it to	336	Replaces the callback on the specified miniport (after converting it to
…		…
324	=item rcv $port, $smartmatch => $callback->(@msg), ...	341	=item rcv $port, $smartmatch => $callback->(@msg), ...
325		342
326	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...	343	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
327		344
328	Register callbacks to be called on matching messages on the given full	345	Register callbacks to be called on matching messages on the given full
329	port (after converting it to one if required).	346	port (after converting it to one if required) and return the port.
330		347
331	The callback has to return a true value when its work is done, after	348	The callback has to return a true value when its work is done, after
332	which is will be removed, or a false value in which case it will stay	349	which is will be removed, or a false value in which case it will stay
333	registered.	350	registered.
334		351
335	The global C<$SELF> (exported by this module) contains C<$port> while	352	The global C<$SELF> (exported by this module) contains C<$port> while
336	executing the callback.	353	executing the callback.
337		354
338	Runtime errors wdurign callback execution will result in the port being	355	Runtime errors during callback execution will result in the port being
339	C<kil>ed.	356	C<kil>ed.
340		357
341	If the match is an array reference, then it will be matched against the	358	If the match is an array reference, then it will be matched against the
342	first elements of the message, otherwise only the first element is being	359	first elements of the message, otherwise only the first element is being
343	matched.	360	matched.
…		…
346	exported by this module) matches any single element of the message.	363	exported by this module) matches any single element of the message.
347		364
348	While not required, it is highly recommended that the first matching	365	While not required, it is highly recommended that the first matching
349	element is a string identifying the message. The one-string-only match is	366	element is a string identifying the message. The one-string-only match is
350	also the most efficient match (by far).	367	also the most efficient match (by far).
		368
		369	Example: create a port and bind receivers on it in one go.
		370
		371	my $port = rcv port,
		372	msg1 => sub { ...; 0 },
		373	msg2 => sub { ...; 0 },
		374	;
		375
		376	Example: create a port, bind receivers and send it in a message elsewhere
		377	in one go:
		378
		379	snd $otherport, reply =>
		380	rcv port,
		381	msg1 => sub { ...; 0 },
		382	...
		383	;
351		384
352	=cut	385	=cut
353		386
354	sub rcv($@) {	387	sub rcv($@) {
355	my $port = shift;	388	my $port = shift;
…		…
462	}	495	}
463	}	496	}
464		497
465	=item $guard = mon $port, $cb->(@reason)	498	=item $guard = mon $port, $cb->(@reason)
466		499
467	=item $guard = mon $port, $otherport	500	=item $guard = mon $port, $rcvport
468		501
		502	=item $guard = mon $port
		503
469	=item $guard = mon $port, $otherport, @msg	504	=item $guard = mon $port, $rcvport, @msg
470		505
471	Monitor the given port and do something when the port is killed.	506	Monitor the given port and do something when the port is killed or
		507	messages to it were lost, and optionally return a guard that can be used
		508	to stop monitoring again.
472		509
		510	C<mon> effectively guarantees that, in the absence of hardware failures,
		511	that after starting the monitor, either all messages sent to the port
		512	will arrive, or the monitoring action will be invoked after possible
		513	message loss has been detected. No messages will be lost "in between"
		514	(after the first lost message no further messages will be received by the
		515	port). After the monitoring action was invoked, further messages might get
		516	delivered again.
		517
473	In the first form, the callback is simply called with any number	518	In the first form (callback), the callback is simply called with any
474	of C<@reason> elements (no @reason means that the port was deleted	519	number of C<@reason> elements (no @reason means that the port was deleted
475	"normally"). Note also that I<< the callback B<must> never die >>, so use	520	"normally"). Note also that I<< the callback B<must> never die >>, so use
476	C<eval> if unsure.	521	C<eval> if unsure.
477		522
478	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	523	In the second form (another port given), the other port (C<$rcvport)
479	a @reason was specified, i.e. on "normal" kils nothing happens, while	524	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
480	under all other conditions, the other port is killed with the same reason.	525	"normal" kils nothing happens, while under all other conditions, the other
		526	port is killed with the same reason.
481		527
		528	The third form (kill self) is the same as the second form, except that
		529	C<$rvport> defaults to C<$SELF>.
		530
482	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	531	In the last form (message), a message of the form C<@msg, @reason> will be
		532	C<snd>.
		533
		534	As a rule of thumb, monitoring requests should always monitor a port from
		535	a local port (or callback). The reason is that kill messages might get
		536	lost, just like any other message. Another less obvious reason is that
		537	even monitoring requests can get lost (for exmaple, when the connection
		538	to the other node goes down permanently). When monitoring a port locally
		539	these problems do not exist.
483		540
484	Example: call a given callback when C<$port> is killed.	541	Example: call a given callback when C<$port> is killed.
485		542
486	mon $port, sub { warn "port died because of <@_>\n" };	543	mon $port, sub { warn "port died because of <@_>\n" };
487		544
488	Example: kill ourselves when C<$port> is killed abnormally.	545	Example: kill ourselves when C<$port> is killed abnormally.
489		546
490	mon $port, $self;	547	mon $port;
491		548
492	Example: send us a restart message another C<$port> is killed.	549	Example: send us a restart message when another C<$port> is killed.
493		550
494	mon $port, $self => "restart";	551	mon $port, $self => "restart";
495		552
496	=cut	553	=cut
497		554
498	sub mon {	555	sub mon {
499	my ($noderef, $port) = split /#/, shift, 2;	556	my ($noderef, $port) = split /#/, shift, 2;
500		557
501	my $node = $NODE{$noderef} \|\| add_node $noderef;	558	my $node = $NODE{$noderef} \|\| add_node $noderef;
502		559
503	my $cb = shift;	560	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
504		561
505	unless (ref $cb) {	562	unless (ref $cb) {
506	if (@_) {	563	if (@_) {
507	# send a kill info message	564	# send a kill info message
508	my (@msg) = ($cb, @_);	565	my (@msg) = ($cb, @_);
…		…
539	=cut	596	=cut
540		597
541	sub mon_guard {	598	sub mon_guard {
542	my ($port, @refs) = @_;	599	my ($port, @refs) = @_;
543		600
		601	#TODO: mon-less form?
		602
544	mon $port, sub { 0 && @refs }	603	mon $port, sub { 0 && @refs }
545	}	604	}
546		605
547	=item lnk $port1, $port2
548
549	Link two ports. This is simply a shorthand for:
550
551	mon $port1, $port2;
552	mon $port2, $port1;
553
554	It means that if either one is killed abnormally, the other one gets
555	killed as well.
556
557	=item kil $port[, @reason]	606	=item kil $port[, @reason]
558		607
559	Kill the specified port with the given C<@reason>.	608	Kill the specified port with the given C<@reason>.
560		609
561	If no C<@reason> is specified, then the port is killed "normally" (linked	610	If no C<@reason> is specified, then the port is killed "normally" (linked
…		…
567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	616	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
568	will be reported as reason C<< die => $@ >>.	617	will be reported as reason C<< die => $@ >>.
569		618
570	Transport/communication errors are reported as C<< transport_error =>	619	Transport/communication errors are reported as C<< transport_error =>
571	$message >>.	620	$message >>.
		621
		622	=cut
		623
		624	=item $port = spawn $node, $initfunc[, @initdata]
		625
		626	Creates a port on the node C<$node> (which can also be a port ID, in which
		627	case it's the node where that port resides).
		628
		629	The port ID of the newly created port is return immediately, and it is
		630	permissible to immediately start sending messages or monitor the port.
		631
		632	After the port has been created, the init function is
		633	called. This function must be a fully-qualified function name
		634	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		635	program, use C<::name>.
		636
		637	If the function doesn't exist, then the node tries to C<require>
		638	the package, then the package above the package and so on (e.g.
		639	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		640	exists or it runs out of package names.
		641
		642	The init function is then called with the newly-created port as context
		643	object (C<$SELF>) and the C<@initdata> values as arguments.
		644
		645	A common idiom is to pass your own port, monitor the spawned port, and
		646	in the init function, monitor the original port. This two-way monitoring
		647	ensures that both ports get cleaned up when there is a problem.
		648
		649	Example: spawn a chat server port on C<$othernode>.
		650
		651	# this node, executed from within a port context:
		652	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		653	mon $server;
		654
		655	# init function on C<$othernode>
		656	sub connect {
		657	my ($srcport) = @_;
		658
		659	mon $srcport;
		660
		661	rcv $SELF, sub {
		662	...
		663	};
		664	}
		665
		666	=cut
		667
		668	sub _spawn {
		669	my $port = shift;
		670	my $init = shift;
		671
		672	local $SELF = "$NODE#$port";
		673	eval {
		674	&{ load_func $init }
		675	};
		676	_self_die if $@;
		677	}
		678
		679	sub spawn(@) {
		680	my ($noderef, undef) = split /#/, shift, 2;
		681
		682	my $id = "$RUNIQ." . $ID++;
		683
		684	$_[0] =~ /::/
		685	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		686
		687	($NODE{$noderef} \|\| add_node $noderef)
		688	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		689
		690	"$noderef#$id"
		691	}
572		692
573	=back	693	=back
574		694
575	=head1 NODE MESSAGES	695	=head1 NODE MESSAGES
576		696
…		…
618		738
619	=back	739	=back
620		740
621	=head1 AnyEvent::MP vs. Distributed Erlang	741	=head1 AnyEvent::MP vs. Distributed Erlang
622		742
623	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	743	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
624	== aemp node, erlang process == aemp port), so many of the documents and	744	== aemp node, Erlang process == aemp port), so many of the documents and
625	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	745	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
626	sample:	746	sample:
627		747
628	http://www.erlang.se/doc/programming_rules.shtml	748	http://www.Erlang.se/doc/programming_rules.shtml
629	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	749	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
630	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	750	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
631	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	751	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
632		752
633	Despite the similarities, there are also some important differences:	753	Despite the similarities, there are also some important differences:
634		754
635	=over 4	755	=over 4
636		756
…		…
647		767
648	Erlang uses processes that selctively receive messages, and therefore	768	Erlang uses processes that selctively receive messages, and therefore
649	needs a queue. AEMP is event based, queuing messages would serve no useful	769	needs a queue. AEMP is event based, queuing messages would serve no useful
650	purpose.	770	purpose.
651		771
652	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	772	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
653		773
654	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	774	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
655		775
656	Sending messages in erlang is synchronous and blocks the process. AEMP	776	Sending messages in Erlang is synchronous and blocks the process. AEMP
657	sends are immediate, connection establishment is handled in the	777	sends are immediate, connection establishment is handled in the
658	background.	778	background.
659		779
660	=item * Erlang can silently lose messages, AEMP cannot.	780	=item * Erlang can silently lose messages, AEMP cannot.
661		781
…		…
664	and c, and the other side only receives messages a and c).	784	and c, and the other side only receives messages a and c).
665		785
666	AEMP guarantees correct ordering, and the guarantee that there are no	786	AEMP guarantees correct ordering, and the guarantee that there are no
667	holes in the message sequence.	787	holes in the message sequence.
668		788
669	=item * In erlang, processes can be declared dead and later be found to be	789	=item * In Erlang, processes can be declared dead and later be found to be
670	alive.	790	alive.
671		791
672	In erlang it can happen that a monitored process is declared dead and	792	In Erlang it can happen that a monitored process is declared dead and
673	linked processes get killed, but later it turns out that the process is	793	linked processes get killed, but later it turns out that the process is
674	still alive - and can receive messages.	794	still alive - and can receive messages.
675		795
676	In AEMP, when port monitoring detects a port as dead, then that port will	796	In AEMP, when port monitoring detects a port as dead, then that port will
677	eventually be killed - it cannot happen that a node detects a port as dead	797	eventually be killed - it cannot happen that a node detects a port as dead
678	and then later sends messages to it, finding it is still alive.	798	and then later sends messages to it, finding it is still alive.
679		799
680	=item * Erlang can send messages to the wrong port, AEMP does not.	800	=item * Erlang can send messages to the wrong port, AEMP does not.
681		801
682	In erlang it is quite possible that a node that restarts reuses a process	802	In Erlang it is quite possible that a node that restarts reuses a process
683	ID known to other nodes for a completely different process, causing	803	ID known to other nodes for a completely different process, causing
684	messages destined for that process to end up in an unrelated process.	804	messages destined for that process to end up in an unrelated process.
685		805
686	AEMP never reuses port IDs, so old messages or old port IDs floating	806	AEMP never reuses port IDs, so old messages or old port IDs floating
687	around in the network will not be sent to an unrelated port.	807	around in the network will not be sent to an unrelated port.
…		…
693	securely authenticate nodes.	813	securely authenticate nodes.
694		814
695	=item * The AEMP protocol is optimised for both text-based and binary	815	=item * The AEMP protocol is optimised for both text-based and binary
696	communications.	816	communications.
697		817
698	The AEMP protocol, unlike the erlang protocol, supports both	818	The AEMP protocol, unlike the Erlang protocol, supports both
699	language-independent text-only protocols (good for debugging) and binary,	819	language-independent text-only protocols (good for debugging) and binary,
700	language-specific serialisers (e.g. Storable).	820	language-specific serialisers (e.g. Storable).
701		821
702	It has also been carefully designed to be implementable in other languages	822	It has also been carefully designed to be implementable in other languages
703	with a minimum of work while gracefully degrading fucntionality to make the	823	with a minimum of work while gracefully degrading fucntionality to make the
704	protocol simple.	824	protocol simple.
705		825
		826	=item * AEMP has more flexible monitoring options than Erlang.
		827
		828	In Erlang, you can chose to receive I<all> exit signals as messages
		829	or I<none>, there is no in-between, so monitoring single processes is
		830	difficult to implement. Monitoring in AEMP is more flexible than in
		831	Erlang, as one can choose between automatic kill, exit message or callback
		832	on a per-process basis.
		833
		834	=item * Erlang tries to hide remote/local connections, AEMP does not.
		835
		836	Monitoring in Erlang is not an indicator of process death/crashes,
		837	as linking is (except linking is unreliable in Erlang).
		838
		839	In AEMP, you don't "look up" registered port names or send to named ports
		840	that might or might not be persistent. Instead, you normally spawn a port
		841	on the remote node. The init function monitors the you, and you monitor
		842	the remote port. Since both monitors are local to the node, they are much
		843	more reliable.
		844
		845	This also saves round-trips and avoids sending messages to the wrong port
		846	(hard to do in Erlang).
		847
706	=back	848	=back
707		849
708	=head1 SEE ALSO	850	=head1 SEE ALSO
709		851
710	L<AnyEvent>.	852	L<AnyEvent>.

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents): Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs. Revision 1.42 by root, Sun Aug 9 00:41:49 2009 UTC

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs.
Revision 1.42 by root, Sun Aug 9 00:41:49 2009 UTC