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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.30 by root, Tue Aug 4 23:35:51 2009 UTC vs.
Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC

…		…
23		23
24	# more, smarter, matches (_any_ is exported by this module)	24	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	25	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		27
		28	# linking two ports, so they both crash together
		29	lnk $port1, $port2;
		30
		31	# monitoring
		32	mon $port, $cb->(@msg) # callback is invoked on death
		33	mon $port, $otherport # kill otherport on abnormal death
		34	mon $port, $otherport, @msg # send message on death
		35
28	=head1 DESCRIPTION	36	=head1 DESCRIPTION
29		37
30	This module (-family) implements a simple message passing framework.	38	This module (-family) implements a simple message passing framework.
31		39
32	Despite its simplicity, you can securely message other processes running	40	Despite its simplicity, you can securely message other processes running
…		…
103	use base "Exporter";	111	use base "Exporter";
104		112
105	our $VERSION = '0.1';	113	our $VERSION = '0.1';
106	our @EXPORT = qw(	114	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	115	NODE $NODE *SELF node_of _any_
108	resolve_node	116	resolve_node initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	117	snd rcv mon kil reg psub
111	port	118	port
112	);	119	);
113		120
114	our $SELF;	121	our $SELF;
…		…
124	The C<NODE> function returns, and the C<$NODE> variable contains	131	The C<NODE> function returns, and the C<$NODE> variable contains
125	the noderef of the local node. The value is initialised by a call	132	the noderef of the local node. The value is initialised by a call
126	to C<become_public> or C<become_slave>, after which all local port	133	to C<become_public> or C<become_slave>, after which all local port
127	identifiers become invalid.	134	identifiers become invalid.
128		135
129	=item $noderef = node_of $portid	136	=item $noderef = node_of $port
130		137
131	Extracts and returns the noderef from a portid or a noderef.	138	Extracts and returns the noderef from a portid or a noderef.
		139
		140	=item initialise_node $noderef, $seednode, $seednode...
		141
		142	=item initialise_node "slave/", $master, $master...
		143
		144	Before a node can talk to other nodes on the network it has to initialise
		145	itself - the minimum a node needs to know is it's own name, and optionally
		146	it should know the noderefs of some other nodes in the network.
		147
		148	This function initialises a node - it must be called exactly once (or
		149	never) before calling other AnyEvent::MP functions.
		150
		151	All arguments are noderefs, which can be either resolved or unresolved.
		152
		153	There are two types of networked nodes, public nodes and slave nodes:
		154
		155	=over 4
		156
		157	=item public nodes
		158
		159	For public nodes, C<$noderef> must either be a (possibly unresolved)
		160	noderef, in which case it will be resolved, or C<undef> (or missing), in
		161	which case the noderef will be guessed.
		162
		163	Afterwards, the node will bind itself on all endpoints and try to connect
		164	to all additional C<$seednodes> that are specified. Seednodes are optional
		165	and can be used to quickly bootstrap the node into an existing network.
		166
		167	=item slave nodes
		168
		169	When the C<$noderef> is the special string C<slave/>, then the node will
		170	become a slave node. Slave nodes cannot be contacted from outside and will
		171	route most of their traffic to the master node that they attach to.
		172
		173	At least one additional noderef is required: The node will try to connect
		174	to all of them and will become a slave attached to the first node it can
		175	successfully connect to.
		176
		177	=back
		178
		179	This function will block until all nodes have been resolved and, for slave
		180	nodes, until it has successfully established a connection to a master
		181	server.
		182
		183	Example: become a public node listening on the default node.
		184
		185	initialise_node;
		186
		187	Example: become a public node, and try to contact some well-known master
		188	servers to become part of the network.
		189
		190	initialise_node undef, "master1", "master2";
		191
		192	Example: become a public node listening on port C<4041>.
		193
		194	initialise_node 4041;
		195
		196	Example: become a public node, only visible on localhost port 4044.
		197
		198	initialise_node "locahost:4044";
		199
		200	Example: become a slave node to any of the specified master servers.
		201
		202	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
132		203
133	=item $cv = resolve_node $noderef	204	=item $cv = resolve_node $noderef
134		205
135	Takes an unresolved node reference that may contain hostnames and	206	Takes an unresolved node reference that may contain hostnames and
136	abbreviated IDs, resolves all of them and returns a resolved node	207	abbreviated IDs, resolves all of them and returns a resolved node
…		…
168		239
169	Due to some quirks in how perl exports variables, it is impossible to	240	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	241	just export C<$SELF>, all the symbols called C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	242	module, but only C<$SELF> is currently used.
172		243
173	=item snd $portid, type => @data	244	=item snd $port, type => @data
174		245
175	=item snd $portid, @msg	246	=item snd $port, @msg
176		247
177	Send the given message to the given port ID, which can identify either	248	Send the given message to the given port ID, which can identify either
178	a local or a remote port, and can be either a string or soemthignt hat	249	a local or a remote port, and can be either a string or soemthignt hat
179	stringifies a sa port ID (such as a port object :).	250	stringifies a sa port ID (such as a port object :).
180		251
…		…
190	JSON is used, then only strings, numbers and arrays and hashes consisting	261	JSON is used, then only strings, numbers and arrays and hashes consisting
191	of those are allowed (no objects). When Storable is used, then anything	262	of those are allowed (no objects). When Storable is used, then anything
192	that Storable can serialise and deserialise is allowed, and for the local	263	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	264	node, anything can be passed.
194		265
195	=item kil $portid[, @reason]
196
197	Kill the specified port with the given C<@reason>.
198
199	If no C<@reason> is specified, then the port is killed "normally" (linked
200	ports will not be kileld, or even notified).
201
202	Otherwise, linked ports get killed with the same reason (second form of
203	C<mon>, see below).
204
205	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
206	will be reported as reason C<< die => $@ >>.
207
208	Transport/communication errors are reported as C<< transport_error =>
209	$message >>.
210
211	=item $guard = mon $portid, $cb->(@reason)
212
213	=item $guard = mon $portid, $otherport
214
215	=item $guard = mon $portid, $otherport, @msg
216
217	Monitor the given port and do something when the port is killed.
218
219	In the first form, the callback is simply called with any number
220	of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.
223
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
225	a @reason was specified, i.e. on "normal" kils nothing happens, while
226	under all other conditions, the other port is killed with the same reason.
227
228	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
229
230	Example: call a given callback when C<$port> is killed.
231
232	mon $port, sub { warn "port died because of <@_>\n" };
233
234	Example: kill ourselves when C<$port> is killed abnormally.
235
236	mon $port, $self;
237
238	Example: send us a restart message another C<$port> is killed.
239
240	mon $port, $self => "restart";
241
242	=cut
243
244	sub mon {
245	my ($noderef, $port) = split /#/, shift, 2;
246
247	my $node = $NODE{$noderef} \|\| add_node $noderef;
248
249	my $cb = shift;
250
251	unless (ref $cb) {
252	if (@_) {
253	# send a kill info message
254	my (@msg) = ($cb, @_);
255	$cb = sub { snd @msg, @_ };
256	} else {
257	# simply kill other port
258	my $port = $cb;
259	$cb = sub { kil $port, @_ if @_ };
260	}
261	}
262
263	$node->monitor ($port, $cb);
264
265	defined wantarray
266	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
267	}
268
269	=item $guard = mon_guard $port, $ref, $ref...
270
271	Monitors the given C<$port> and keeps the passed references. When the port
272	is killed, the references will be freed.
273
274	Optionally returns a guard that will stop the monitoring.
275
276	This function is useful when you create e.g. timers or other watchers and
277	want to free them when the port gets killed:
278
279	$port->rcv (start => sub {
280	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
281	undef $timer if 0.9 < rand;
282	});
283	});
284
285	=cut
286
287	sub mon_guard {
288	my ($port, @refs) = @_;
289
290	mon $port, sub { 0 && @refs }
291	}
292
293	=item lnk $port1, $port2
294
295	Link two ports. This is simply a shorthand for:
296
297	mon $port1, $port2;
298	mon $port2, $port1;
299
300	It means that if either one is killed abnormally, the other one gets
301	killed as well.
302
303	=item $local_port = port	266	=item $local_port = port
304		267
305	Create a new local port object that supports message matching.	268	Create a new local port object that can be used either as a pattern
		269	matching port ("full port") or a single-callback port ("miniport"),
		270	depending on how C<rcv> callbacks are bound to the object.
306		271
307	=item $portid = port { my @msg = @_; $finished }	272	=item $port = port { my @msg = @_; $finished }
308		273
309	Creates a "mini port", that is, a very lightweight port without any	274	Creates a "miniport", that is, a very lightweight port without any pattern
310	pattern matching behind it, and returns its ID.	275	matching behind it, and returns its ID. Semantically the same as creating
		276	a port and calling C<rcv $port, $callback> on it.
311		277
312	The block will be called for every message received on the port. When the	278	The block will be called for every message received on the port. When the
313	callback returns a true value its job is considered "done" and the port	279	callback returns a true value its job is considered "done" and the port
314	will be destroyed. Otherwise it will stay alive.	280	will be destroyed. Otherwise it will stay alive.
315		281
316	The message will be passed as-is, no extra argument (i.e. no port id) will	282	The message will be passed as-is, no extra argument (i.e. no port id) will
317	be passed to the callback.	283	be passed to the callback.
318		284
319	If you need the local port id in the callback, this works nicely:	285	If you need the local port id in the callback, this works nicely:
320		286
321	my $port; $port = miniport {	287	my $port; $port = port {
322	snd $otherport, reply => $port;	288	snd $otherport, reply => $port;
323	};	289	};
324		290
325	=cut	291	=cut
		292
		293	sub rcv($@);
326		294
327	sub port(;&) {	295	sub port(;&) {
328	my $id = "$UNIQ." . $ID++;	296	my $id = "$UNIQ." . $ID++;
329	my $port = "$NODE#$id";	297	my $port = "$NODE#$id";
330		298
331	if (@_) {	299	if (@_) {
		300	rcv $port, shift;
		301	} else {
		302	$PORT{$id} = sub { }; # nop
		303	}
		304
		305	$port
		306	}
		307
		308	=item reg $port, $name
		309
		310	=item reg $name
		311
		312	Registers the given port (or C<$SELF><<< if missing) under the name
		313	C<$name>. If the name already exists it is replaced.
		314
		315	A port can only be registered under one well known name.
		316
		317	A port automatically becomes unregistered when it is killed.
		318
		319	=cut
		320
		321	sub reg(@) {
		322	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		323
		324	$REG{$_[0]} = $port;
		325	}
		326
		327	=item rcv $port, $callback->(@msg)
		328
		329	Replaces the callback on the specified miniport (after converting it to
		330	one if required).
		331
		332	=item rcv $port, tagstring => $callback->(@msg), ...
		333
		334	=item rcv $port, $smartmatch => $callback->(@msg), ...
		335
		336	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		337
		338	Register callbacks to be called on matching messages on the given full
		339	port (after converting it to one if required) and return the port.
		340
		341	The callback has to return a true value when its work is done, after
		342	which is will be removed, or a false value in which case it will stay
		343	registered.
		344
		345	The global C<$SELF> (exported by this module) contains C<$port> while
		346	executing the callback.
		347
		348	Runtime errors wdurign callback execution will result in the port being
		349	C<kil>ed.
		350
		351	If the match is an array reference, then it will be matched against the
		352	first elements of the message, otherwise only the first element is being
		353	matched.
		354
		355	Any element in the match that is specified as C<_any_> (a function
		356	exported by this module) matches any single element of the message.
		357
		358	While not required, it is highly recommended that the first matching
		359	element is a string identifying the message. The one-string-only match is
		360	also the most efficient match (by far).
		361
		362	Example: create a port and bind receivers on it in one go.
		363
		364	my $port = rcv port,
		365	msg1 => sub { ...; 0 },
		366	msg2 => sub { ...; 0 },
		367	;
		368
		369	Example: create a port, bind receivers and send it in a message elsewhere
		370	in one go:
		371
		372	snd $otherport, reply =>
		373	rcv port,
		374	msg1 => sub { ...; 0 },
		375	...
		376	;
		377
		378	=cut
		379
		380	sub rcv($@) {
		381	my $port = shift;
		382	my ($noderef, $portid) = split /#/, $port, 2;
		383
		384	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		385	or Carp::croak "$port: rcv can only be called on local ports, caught";
		386
		387	if (@_ == 1) {
332	my $cb = shift;	388	my $cb = shift;
		389	delete $PORT_DATA{$portid};
333	$PORT{$id} = sub {	390	$PORT{$portid} = sub {
334	local $SELF = $port;	391	local $SELF = $port;
335	eval {	392	eval {
336	&$cb	393	&$cb
337	and kil $id;	394	and kil $port;
338	};	395	};
339	_self_die if $@;	396	_self_die if $@;
340	};	397	};
341	} else {	398	} else {
		399	my $self = $PORT_DATA{$portid} \|\|= do {
342	my $self = bless {	400	my $self = bless {
343	id => "$NODE#$id",	401	id => $port,
344	}, "AnyEvent::MP::Port";	402	}, "AnyEvent::MP::Port";
345		403
346	$PORT_DATA{$id} = $self;
347	$PORT{$id} = sub {	404	$PORT{$portid} = sub {
348	local $SELF = $port;	405	local $SELF = $port;
349		406
350	eval {	407	eval {
351	for (@{ $self->{rc0}{$_[0]} }) {	408	for (@{ $self->{rc0}{$_[0]} }) {
352	$_ && &{$_->[0]}	409	$_ && &{$_->[0]}
353	&& undef $_;	410	&& undef $_;
354	}	411	}
355		412
356	for (@{ $self->{rcv}{$_[0]} }) {	413	for (@{ $self->{rcv}{$_[0]} }) {
357	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	414	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
358	&& &{$_->[0]}	415	&& &{$_->[0]}
359	&& undef $_;	416	&& undef $_;
360	}	417	}
361		418
362	for (@{ $self->{any} }) {	419	for (@{ $self->{any} }) {
363	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	420	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
364	&& &{$_->[0]}	421	&& &{$_->[0]}
365	&& undef $_;	422	&& undef $_;
		423	}
366	}	424	};
		425	_self_die if $@;
367	};	426	};
368	_self_die if $@;	427
		428	$self
369	};	429	};
370	}
371		430
372	$port
373	}
374
375	=item reg $portid, $name
376
377	Registers the given port under the name C<$name>. If the name already
378	exists it is replaced.
379
380	A port can only be registered under one well known name.
381
382	A port automatically becomes unregistered when it is killed.
383
384	=cut
385
386	sub reg(@) {
387	my ($portid, $name) = @_;
388
389	$REG{$name} = $portid;
390	}
391
392	=item rcv $portid, tagstring => $callback->(@msg), ...
393
394	=item rcv $portid, $smartmatch => $callback->(@msg), ...
395
396	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
397
398	Register callbacks to be called on matching messages on the given port.
399
400	The callback has to return a true value when its work is done, after
401	which is will be removed, or a false value in which case it will stay
402	registered.
403
404	The global C<$SELF> (exported by this module) contains C<$portid> while
405	executing the callback.
406
407	Runtime errors wdurign callback execution will result in the port being
408	C<kil>ed.
409
410	If the match is an array reference, then it will be matched against the
411	first elements of the message, otherwise only the first element is being
412	matched.
413
414	Any element in the match that is specified as C<_any_> (a function
415	exported by this module) matches any single element of the message.
416
417	While not required, it is highly recommended that the first matching
418	element is a string identifying the message. The one-string-only match is
419	also the most efficient match (by far).
420
421	=cut
422
423	sub rcv($@) {
424	my ($noderef, $port) = split /#/, shift, 2;
425
426	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
427	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
428
429	my $self = $PORT_DATA{$port}
430	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
431
432	"AnyEvent::MP::Port" eq ref $self	431	"AnyEvent::MP::Port" eq ref $self
433	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	432	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
434		433
435	while (@_) {	434	while (@_) {
436	my ($match, $cb) = splice @_, 0, 2;	435	my ($match, $cb) = splice @_, 0, 2;
437		436
438	if (!ref $match) {	437	if (!ref $match) {
439	push @{ $self->{rc0}{$match} }, [$cb];	438	push @{ $self->{rc0}{$match} }, [$cb];
440	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
441	my ($type, @match) = @$match;	440	my ($type, @match) = @$match;
442	@match	441	@match
443	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
444	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
445	} else {	444	} else {
446	push @{ $self->{any} }, [$cb, $match];	445	push @{ $self->{any} }, [$cb, $match];
		446	}
447	}	447	}
448	}	448	}
		449
		450	$port
449	}	451	}
450		452
451	=item $closure = psub { BLOCK }	453	=item $closure = psub { BLOCK }
452		454
453	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	455	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
484	$res	486	$res
485	}	487	}
486	}	488	}
487	}	489	}
488		490
489	=back	491	=item $guard = mon $port, $cb->(@reason)
490		492
491	=head1 FUNCTIONS FOR NODES	493	=item $guard = mon $port, $rcvport
492		494
493	=over 4	495	=item $guard = mon $port
494		496
495	=item become_public $noderef	497	=item $guard = mon $port, $rcvport, @msg
496		498
497	Tells the node to become a public node, i.e. reachable from other nodes.	499	Monitor the given port and do something when the port is killed, and
		500	optionally return a guard that can be used to stop monitoring again.
498		501
499	The first argument is the (unresolved) node reference of the local node	502	In the first form (callback), the callback is simply called with any
500	(if missing then the empty string is used).	503	number of C<@reason> elements (no @reason means that the port was deleted
		504	"normally"). Note also that I<< the callback B<must> never die >>, so use
		505	C<eval> if unsure.
501		506
502	It is quite common to not specify anything, in which case the local node	507	In the second form (another port given), the other port (C<$rcvport)
503	tries to listen on the default port, or to only specify a port number, in	508	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
504	which case AnyEvent::MP tries to guess the local addresses.	509	"normal" kils nothing happens, while under all other conditions, the other
		510	port is killed with the same reason.
505		511
		512	The third form (kill self) is the same as the second form, except that
		513	C<$rvport> defaults to C<$SELF>.
		514
		515	In the last form (message), a message of the form C<@msg, @reason> will be
		516	C<snd>.
		517
		518	Example: call a given callback when C<$port> is killed.
		519
		520	mon $port, sub { warn "port died because of <@_>\n" };
		521
		522	Example: kill ourselves when C<$port> is killed abnormally.
		523
		524	mon $port;
		525
		526	Example: send us a restart message when another C<$port> is killed.
		527
		528	mon $port, $self => "restart";
		529
506	=cut	530	=cut
		531
		532	sub mon {
		533	my ($noderef, $port) = split /#/, shift, 2;
		534
		535	my $node = $NODE{$noderef} \|\| add_node $noderef;
		536
		537	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		538
		539	unless (ref $cb) {
		540	if (@_) {
		541	# send a kill info message
		542	my (@msg) = @_;
		543	$cb = sub { snd @msg, @_ };
		544	} else {
		545	# simply kill other port
		546	my $port = $cb;
		547	$cb = sub { kil $port, @_ if @_ };
		548	}
		549	}
		550
		551	$node->monitor ($port, $cb);
		552
		553	defined wantarray
		554	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		555	}
		556
		557	=item $guard = mon_guard $port, $ref, $ref...
		558
		559	Monitors the given C<$port> and keeps the passed references. When the port
		560	is killed, the references will be freed.
		561
		562	Optionally returns a guard that will stop the monitoring.
		563
		564	This function is useful when you create e.g. timers or other watchers and
		565	want to free them when the port gets killed:
		566
		567	$port->rcv (start => sub {
		568	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		569	undef $timer if 0.9 < rand;
		570	});
		571	});
		572
		573	=cut
		574
		575	sub mon_guard {
		576	my ($port, @refs) = @_;
		577
		578	#TODO: mon-less form?
		579
		580	mon $port, sub { 0 && @refs }
		581	}
		582
		583	=item lnk $port1, $port2
		584
		585	=item lnk $otherport
		586
		587	Link two ports. This is simply a shorthand for:
		588
		589	mon $port1, $port2;
		590	mon $port2, $port1;
		591
		592	It means that if either one is killed abnormally, the other one gets
		593	killed as well.
		594
		595	The one-argument form assumes that one port is C<$SELF>.
		596
		597	=cut
		598
		599	sub lnk {
		600	my $port1 = shift;
		601	my $port2 = @_ ? shift : $SELF \|\| Carp::croak 'lnk: called with one argument only, but $SELF not set,';
		602
		603	mon $port1, $port2;
		604	mon $port2, $port1;
		605	}
		606
		607	=item kil $port[, @reason]
		608
		609	Kill the specified port with the given C<@reason>.
		610
		611	If no C<@reason> is specified, then the port is killed "normally" (linked
		612	ports will not be kileld, or even notified).
		613
		614	Otherwise, linked ports get killed with the same reason (second form of
		615	C<mon>, see below).
		616
		617	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		618	will be reported as reason C<< die => $@ >>.
		619
		620	Transport/communication errors are reported as C<< transport_error =>
		621	$message >>.
507		622
508	=back	623	=back
509		624
510	=head1 NODE MESSAGES	625	=head1 NODE MESSAGES
511		626
…		…
553		668
554	=back	669	=back
555		670
556	=head1 AnyEvent::MP vs. Distributed Erlang	671	=head1 AnyEvent::MP vs. Distributed Erlang
557		672
558	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	673	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
559	== aemp node, erlang process == aemp port), so many of the documents and	674	== aemp node, Erlang process == aemp port), so many of the documents and
560	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	675	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
561	sample:	676	sample:
562		677
563	http://www.erlang.se/doc/programming_rules.shtml	678	http://www.Erlang.se/doc/programming_rules.shtml
564	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	679	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
565	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	680	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
566	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	681	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
567		682
568	Despite the similarities, there are also some important differences:	683	Despite the similarities, there are also some important differences:
569		684
570	=over 4	685	=over 4
571		686
…		…
582		697
583	Erlang uses processes that selctively receive messages, and therefore	698	Erlang uses processes that selctively receive messages, and therefore
584	needs a queue. AEMP is event based, queuing messages would serve no useful	699	needs a queue. AEMP is event based, queuing messages would serve no useful
585	purpose.	700	purpose.
586		701
587	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	702	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
588		703
589	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	704	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
590		705
591	Sending messages in erlang is synchronous and blocks the process. AEMP	706	Sending messages in Erlang is synchronous and blocks the process. AEMP
592	sends are immediate, connection establishment is handled in the	707	sends are immediate, connection establishment is handled in the
593	background.	708	background.
594		709
595	=item * Erlang can silently lose messages, AEMP cannot.	710	=item * Erlang can silently lose messages, AEMP cannot.
596		711
…		…
599	and c, and the other side only receives messages a and c).	714	and c, and the other side only receives messages a and c).
600		715
601	AEMP guarantees correct ordering, and the guarantee that there are no	716	AEMP guarantees correct ordering, and the guarantee that there are no
602	holes in the message sequence.	717	holes in the message sequence.
603		718
604	=item * In erlang, processes can be declared dead and later be found to be	719	=item * In Erlang, processes can be declared dead and later be found to be
605	alive.	720	alive.
606		721
607	In erlang it can happen that a monitored process is declared dead and	722	In Erlang it can happen that a monitored process is declared dead and
608	linked processes get killed, but later it turns out that the process is	723	linked processes get killed, but later it turns out that the process is
609	still alive - and can receive messages.	724	still alive - and can receive messages.
610		725
611	In AEMP, when port monitoring detects a port as dead, then that port will	726	In AEMP, when port monitoring detects a port as dead, then that port will
612	eventually be killed - it cannot happen that a node detects a port as dead	727	eventually be killed - it cannot happen that a node detects a port as dead
613	and then later sends messages to it, finding it is still alive.	728	and then later sends messages to it, finding it is still alive.
614		729
615	=item * Erlang can send messages to the wrong port, AEMP does not.	730	=item * Erlang can send messages to the wrong port, AEMP does not.
616		731
617	In erlang it is quite possible that a node that restarts reuses a process	732	In Erlang it is quite possible that a node that restarts reuses a process
618	ID known to other nodes for a completely different process, causing	733	ID known to other nodes for a completely different process, causing
619	messages destined for that process to end up in an unrelated process.	734	messages destined for that process to end up in an unrelated process.
620		735
621	AEMP never reuses port IDs, so old messages or old port IDs floating	736	AEMP never reuses port IDs, so old messages or old port IDs floating
622	around in the network will not be sent to an unrelated port.	737	around in the network will not be sent to an unrelated port.
…		…
628	securely authenticate nodes.	743	securely authenticate nodes.
629		744
630	=item * The AEMP protocol is optimised for both text-based and binary	745	=item * The AEMP protocol is optimised for both text-based and binary
631	communications.	746	communications.
632		747
633	The AEMP protocol, unlike the erlang protocol, supports both	748	The AEMP protocol, unlike the Erlang protocol, supports both
634	language-independent text-only protocols (good for debugging) and binary,	749	language-independent text-only protocols (good for debugging) and binary,
635	language-specific serialisers (e.g. Storable).	750	language-specific serialisers (e.g. Storable).
636		751
637	It has also been carefully designed to be implementable in other languages	752	It has also been carefully designed to be implementable in other languages
638	with a minimum of work while gracefully degrading fucntionality to make the	753	with a minimum of work while gracefully degrading fucntionality to make the
639	protocol simple.	754	protocol simple.
640		755
		756	=item * AEMP has more flexible monitoring options than Erlang.
		757
		758	In Erlang, you can chose to receive I<all> exit signals as messages
		759	or I<none>, there is no in-between, so monitoring single processes is
		760	difficult to implement. Monitoring in AEMP is more flexible than in
		761	Erlang, as one can choose between automatic kill, exit message or callback
		762	on a per-process basis.
		763
		764	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.
		765
		766	Monitoring in Erlang is not an indicator of process death/crashes,
		767	as linking is (except linking is unreliable in Erlang). In AEMP, the
		768	semantics of monitoring and linking are identical, linking is simply
		769	two-way monitoring with automatic kill.
		770
641	=back	771	=back
642		772
643	=head1 SEE ALSO	773	=head1 SEE ALSO
644		774
645	L<AnyEvent>.	775	L<AnyEvent>.

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Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC