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Revision 1.49 by root, Thu Aug 13 15:29:58 2009 UTC vs.
Revision 1.79 by root, Fri Sep 4 21:52:09 2009 UTC

4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use AnyEvent::MP; 7 use AnyEvent::MP;
8 8
9 $NODE # contains this node's noderef 9 $NODE # contains this node's node ID
10 NODE # returns this node's noderef 10 NODE # returns this node's node ID
11 NODE $port # returns the noderef of the port
12 11
13 $SELF # receiving/own port id in rcv callbacks 12 $SELF # receiving/own port id in rcv callbacks
14 13
15 # initialise the node so it can send/receive messages 14 # initialise the node so it can send/receive messages
16 initialise_node; # -OR- 15 configure;
17 initialise_node "localhost:4040"; # -OR-
18 initialise_node "slave/", "localhost:4040"
19 16
20 # ports are message endpoints 17 # ports are message destinations
21 18
22 # sending messages 19 # sending messages
23 snd $port, type => data...; 20 snd $port, type => data...;
24 snd $port, @msg; 21 snd $port, @msg;
25 snd @msg_with_first_element_being_a_port; 22 snd @msg_with_first_element_being_a_port;
26 23
27 # creating/using miniports 24 # creating/using ports, the simple way
28 my $miniport = port { my @msg = @_; 0 }; 25 my $simple_port = port { my @msg = @_ };
29 26
30 # creating/using full ports 27 # creating/using ports, tagged message matching
31 my $port = port; 28 my $port = port;
32 rcv $port, smartmatch => $cb->(@msg);
33 rcv $port, ping => sub { snd $_[0], "pong"; 0 }; 29 rcv $port, ping => sub { snd $_[0], "pong" };
34 rcv $port, pong => sub { warn "pong received\n"; 0 }; 30 rcv $port, pong => sub { warn "pong received\n" };
35
36 # more, smarter, matches (_any_ is exported by this module)
37 rcv $port, [child_died => $pid] => sub { ...
38 rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
39 31
40 # create a port on another node 32 # create a port on another node
41 my $port = spawn $node, $initfunc, @initdata; 33 my $port = spawn $node, $initfunc, @initdata;
42 34
43 # monitoring 35 # monitoring
45 mon $port, $otherport # kill otherport on abnormal death 37 mon $port, $otherport # kill otherport on abnormal death
46 mon $port, $otherport, @msg # send message on death 38 mon $port, $otherport, @msg # send message on death
47 39
48=head1 CURRENT STATUS 40=head1 CURRENT STATUS
49 41
42 bin/aemp - stable.
50 AnyEvent::MP - stable API, should work 43 AnyEvent::MP - stable API, should work.
51 AnyEvent::MP::Intro - outdated 44 AnyEvent::MP::Intro - explains most concepts.
52 AnyEvent::MP::Kernel - WIP
53 AnyEvent::MP::Transport - mostly stable 45 AnyEvent::MP::Kernel - mostly stable.
46 AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
54 47
55 stay tuned. 48stay tuned.
56 49
57=head1 DESCRIPTION 50=head1 DESCRIPTION
58 51
59This module (-family) implements a simple message passing framework. 52This module (-family) implements a simple message passing framework.
60 53
61Despite its simplicity, you can securely message other processes running 54Despite its simplicity, you can securely message other processes running
62on the same or other hosts. 55on the same or other hosts, and you can supervise entities remotely.
63 56
64For an introduction to this module family, see the L<AnyEvent::MP::Intro> 57For an introduction to this module family, see the L<AnyEvent::MP::Intro>
65manual page. 58manual page and the examples under F<eg/>.
66
67At the moment, this module family is severly broken and underdocumented,
68so do not use. This was uploaded mainly to reserve the CPAN namespace -
69stay tuned!
70 59
71=head1 CONCEPTS 60=head1 CONCEPTS
72 61
73=over 4 62=over 4
74 63
75=item port 64=item port
76 65
77A port is something you can send messages to (with the C<snd> function). 66Not to be confused with a TCP port, a "port" is something you can send
67messages to (with the C<snd> function).
78 68
79Some ports allow you to register C<rcv> handlers that can match specific 69Ports allow you to register C<rcv> handlers that can match all or just
80messages. All C<rcv> handlers will receive messages they match, messages 70some messages. Messages send to ports will not be queued, regardless of
81will not be queued. 71anything was listening for them or not.
82 72
83=item port id - C<noderef#portname> 73=item port ID - C<nodeid#portname>
84 74
85A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as 75A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
86separator, and a port name (a printable string of unspecified format). An 76separator, and a port name (a printable string of unspecified format).
87exception is the the node port, whose ID is identical to its node
88reference.
89 77
90=item node 78=item node
91 79
92A node is a single process containing at least one port - the node 80A node is a single process containing at least one port - the node port,
93port. You can send messages to node ports to find existing ports or to 81which enables nodes to manage each other remotely, and to create new
94create new ports, among other things. 82ports.
95 83
96Nodes are either private (single-process only), slaves (connected to a 84Nodes are either public (have one or more listening ports) or private
97master node only) or public nodes (connectable from unrelated nodes). 85(no listening ports). Private nodes cannot talk to other private nodes
86currently.
98 87
99=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> 88=item node ID - C<[a-za-Z0-9_\-.:]+>
100 89
101A node reference is a string that either simply identifies the node (for 90A node ID is a string that uniquely identifies the node within a
102private and slave nodes), or contains a recipe on how to reach a given 91network. Depending on the configuration used, node IDs can look like a
103node (for public nodes). 92hostname, a hostname and a port, or a random string. AnyEvent::MP itself
93doesn't interpret node IDs in any way.
104 94
105This recipe is simply a comma-separated list of C<address:port> pairs (for 95=item binds - C<ip:port>
106TCP/IP, other protocols might look different).
107 96
108Node references come in two flavours: resolved (containing only numerical 97Nodes can only talk to each other by creating some kind of connection to
109addresses) or unresolved (where hostnames are used instead of addresses). 98each other. To do this, nodes should listen on one or more local transport
99endpoints - binds. Currently, only standard C<ip:port> specifications can
100be used, which specify TCP ports to listen on.
110 101
111Before using an unresolved node reference in a message you first have to 102=item seeds - C<host:port>
112resolve it. 103
104When a node starts, it knows nothing about the network. To teach the node
105about the network it first has to contact some other node within the
106network. This node is called a seed.
107
108Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
109are expected to be long-running, and at least one of those should always
110be available. When nodes run out of connections (e.g. due to a network
111error), they try to re-establish connections to some seednodes again to
112join the network.
113
114Apart from being sued for seeding, seednodes are not special in any way -
115every public node can be a seednode.
113 116
114=back 117=back
115 118
116=head1 VARIABLES/FUNCTIONS 119=head1 VARIABLES/FUNCTIONS
117 120
132use base "Exporter"; 135use base "Exporter";
133 136
134our $VERSION = $AnyEvent::MP::Kernel::VERSION; 137our $VERSION = $AnyEvent::MP::Kernel::VERSION;
135 138
136our @EXPORT = qw( 139our @EXPORT = qw(
137 NODE $NODE *SELF node_of _any_ 140 NODE $NODE *SELF node_of after
138 resolve_node initialise_node 141 configure
139 snd rcv mon kil reg psub spawn 142 snd rcv mon mon_guard kil reg psub spawn
140 port 143 port
141); 144);
142 145
143our $SELF; 146our $SELF;
144 147
148 kil $SELF, die => $msg; 151 kil $SELF, die => $msg;
149} 152}
150 153
151=item $thisnode = NODE / $NODE 154=item $thisnode = NODE / $NODE
152 155
153The C<NODE> function returns, and the C<$NODE> variable contains 156The C<NODE> function returns, and the C<$NODE> variable contains, the node
154the noderef of the local node. The value is initialised by a call 157ID of the node running in the current process. This value is initialised by
155to C<become_public> or C<become_slave>, after which all local port 158a call to C<configure>.
156identifiers become invalid.
157 159
158=item $noderef = node_of $port 160=item $nodeid = node_of $port
159 161
160Extracts and returns the noderef from a portid or a noderef. 162Extracts and returns the node ID from a port ID or a node ID.
161 163
162=item initialise_node $noderef, $seednode, $seednode... 164=item configure $profile, key => value...
163 165
164=item initialise_node "slave/", $master, $master... 166=item configure key => value...
165 167
166Before a node can talk to other nodes on the network it has to initialise 168Before a node can talk to other nodes on the network (i.e. enter
167itself - the minimum a node needs to know is it's own name, and optionally 169"distributed mode") it has to configure itself - the minimum a node needs
168it should know the noderefs of some other nodes in the network. 170to know is its own name, and optionally it should know the addresses of
171some other nodes in the network to discover other nodes.
169 172
170This function initialises a node - it must be called exactly once (or 173This function configures a node - it must be called exactly once (or
171never) before calling other AnyEvent::MP functions. 174never) before calling other AnyEvent::MP functions.
172 175
173All arguments (optionally except for the first) are noderefs, which can be
174either resolved or unresolved.
175
176The first argument will be looked up in the configuration database first
177(if it is C<undef> then the current nodename will be used instead) to find
178the relevant configuration profile (see L<aemp>). If none is found then
179the default configuration is used. The configuration supplies additional
180seed/master nodes and can override the actual noderef.
181
182There are two types of networked nodes, public nodes and slave nodes:
183
184=over 4 176=over 4
185 177
186=item public nodes 178=item step 1, gathering configuration from profiles
187 179
188For public nodes, C<$noderef> (supplied either directly to 180The function first looks up a profile in the aemp configuration (see the
189C<initialise_node> or indirectly via a profile or the nodename) must be a 181L<aemp> commandline utility). The profile name can be specified via the
190noderef (possibly unresolved, in which case it will be resolved). 182named C<profile> parameter or can simply be the first parameter). If it is
183missing, then the nodename (F<uname -n>) will be used as profile name.
191 184
192After resolving, the node will bind itself on all endpoints and try to 185The profile data is then gathered as follows:
193connect to all additional C<$seednodes> that are specified. Seednodes are
194optional and can be used to quickly bootstrap the node into an existing
195network.
196 186
197=item slave nodes 187First, all remaining key => value pairs (all of which are conveniently
188undocumented at the moment) will be interpreted as configuration
189data. Then they will be overwritten by any values specified in the global
190default configuration (see the F<aemp> utility), then the chain of
191profiles chosen by the profile name (and any C<parent> attributes).
198 192
199When the C<$noderef> (either as given or overriden by the config file) 193That means that the values specified in the profile have highest priority
200is the special string C<slave/>, then the node will become a slave 194and the values specified directly via C<configure> have lowest priority,
201node. Slave nodes cannot be contacted from outside and will route most of 195and can only be used to specify defaults.
202their traffic to the master node that they attach to.
203 196
204At least one additional noderef is required (either by specifying it 197If the profile specifies a node ID, then this will become the node ID of
205directly or because it is part of the configuration profile): The node 198this process. If not, then the profile name will be used as node ID. The
206will try to connect to all of them and will become a slave attached to the 199special node ID of C<anon/> will be replaced by a random node ID.
207first node it can successfully connect to. 200
201=item step 2, bind listener sockets
202
203The next step is to look up the binds in the profile, followed by binding
204aemp protocol listeners on all binds specified (it is possible and valid
205to have no binds, meaning that the node cannot be contacted form the
206outside. This means the node cannot talk to other nodes that also have no
207binds, but it can still talk to all "normal" nodes).
208
209If the profile does not specify a binds list, then a default of C<*> is
210used, meaning the node will bind on a dynamically-assigned port on every
211local IP address it finds.
212
213=item step 3, connect to seed nodes
214
215As the last step, the seeds list from the profile is passed to the
216L<AnyEvent::MP::Global> module, which will then use it to keep
217connectivity with at least one node at any point in time.
208 218
209=back 219=back
210 220
211This function will block until all nodes have been resolved and, for slave 221Example: become a distributed node using the locla node name as profile.
212nodes, until it has successfully established a connection to a master 222This should be the most common form of invocation for "daemon"-type nodes.
213server.
214 223
215Example: become a public node listening on the guessed noderef, or the one 224 configure
216specified via C<aemp> for the current node. This should be the most common
217form of invocation for "daemon"-type nodes.
218 225
219 initialise_node; 226Example: become an anonymous node. This form is often used for commandline
227clients.
220 228
221Example: become a slave node to any of the the seednodes specified via 229 configure nodeid => "anon/";
222C<aemp>. This form is often used for commandline clients.
223 230
224 initialise_node "slave/"; 231Example: configure a node using a profile called seed, which si suitable
232for a seed node as it binds on all local addresses on a fixed port (4040,
233customary for aemp).
225 234
226Example: become a slave node to any of the specified master servers. This 235 # use the aemp commandline utility
227form is also often used for commandline clients. 236 # aemp profile seed nodeid anon/ binds '*:4040'
228 237
229 initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net"; 238 # then use it
239 configure profile => "seed";
230 240
231Example: become a public node, and try to contact some well-known master 241 # or simply use aemp from the shell again:
232servers to become part of the network. 242 # aemp run profile seed
233 243
234 initialise_node undef, "master1", "master2"; 244 # or provide a nicer-to-remember nodeid
235 245 # aemp run profile seed nodeid "$(hostname)"
236Example: become a public node listening on port C<4041>.
237
238 initialise_node 4041;
239
240Example: become a public node, only visible on localhost port 4044.
241
242 initialise_node "localhost:4044";
243
244=item $cv = resolve_node $noderef
245
246Takes an unresolved node reference that may contain hostnames and
247abbreviated IDs, resolves all of them and returns a resolved node
248reference.
249
250In addition to C<address:port> pairs allowed in resolved noderefs, the
251following forms are supported:
252
253=over 4
254
255=item the empty string
256
257An empty-string component gets resolved as if the default port (4040) was
258specified.
259
260=item naked port numbers (e.g. C<1234>)
261
262These are resolved by prepending the local nodename and a colon, to be
263further resolved.
264
265=item hostnames (e.g. C<localhost:1234>, C<localhost>)
266
267These are resolved by using AnyEvent::DNS to resolve them, optionally
268looking up SRV records for the C<aemp=4040> port, if no port was
269specified.
270
271=back
272 246
273=item $SELF 247=item $SELF
274 248
275Contains the current port id while executing C<rcv> callbacks or C<psub> 249Contains the current port id while executing C<rcv> callbacks or C<psub>
276blocks. 250blocks.
277 251
278=item SELF, %SELF, @SELF... 252=item *SELF, SELF, %SELF, @SELF...
279 253
280Due to some quirks in how perl exports variables, it is impossible to 254Due to some quirks in how perl exports variables, it is impossible to
281just export C<$SELF>, all the symbols called C<SELF> are exported by this 255just export C<$SELF>, all the symbols named C<SELF> are exported by this
282module, but only C<$SELF> is currently used. 256module, but only C<$SELF> is currently used.
283 257
284=item snd $port, type => @data 258=item snd $port, type => @data
285 259
286=item snd $port, @msg 260=item snd $port, @msg
287 261
288Send the given message to the given port ID, which can identify either 262Send the given message to the given port, which can identify either a
289a local or a remote port, and can be either a string or soemthignt hat 263local or a remote port, and must be a port ID.
290stringifies a sa port ID (such as a port object :).
291 264
292While the message can be about anything, it is highly recommended to use a 265While the message can be almost anything, it is highly recommended to
293string as first element (a portid, or some word that indicates a request 266use a string as first element (a port ID, or some word that indicates a
294type etc.). 267request type etc.) and to consist if only simple perl values (scalars,
268arrays, hashes) - if you think you need to pass an object, think again.
295 269
296The message data effectively becomes read-only after a call to this 270The message data logically becomes read-only after a call to this
297function: modifying any argument is not allowed and can cause many 271function: modifying any argument (or values referenced by them) is
298problems. 272forbidden, as there can be considerable time between the call to C<snd>
273and the time the message is actually being serialised - in fact, it might
274never be copied as within the same process it is simply handed to the
275receiving port.
299 276
300The type of data you can transfer depends on the transport protocol: when 277The type of data you can transfer depends on the transport protocol: when
301JSON is used, then only strings, numbers and arrays and hashes consisting 278JSON is used, then only strings, numbers and arrays and hashes consisting
302of those are allowed (no objects). When Storable is used, then anything 279of those are allowed (no objects). When Storable is used, then anything
303that Storable can serialise and deserialise is allowed, and for the local 280that Storable can serialise and deserialise is allowed, and for the local
304node, anything can be passed. 281node, anything can be passed. Best rely only on the common denominator of
282these.
305 283
306=item $local_port = port 284=item $local_port = port
307 285
308Create a new local port object that can be used either as a pattern 286Create a new local port object and returns its port ID. Initially it has
309matching port ("full port") or a single-callback port ("miniport"), 287no callbacks set and will throw an error when it receives messages.
310depending on how C<rcv> callbacks are bound to the object.
311 288
312=item $port = port { my @msg = @_; $finished } 289=item $local_port = port { my @msg = @_ }
313 290
314Creates a "miniport", that is, a very lightweight port without any pattern 291Creates a new local port, and returns its ID. Semantically the same as
315matching behind it, and returns its ID. Semantically the same as creating
316a port and calling C<rcv $port, $callback> on it. 292creating a port and calling C<rcv $port, $callback> on it.
317 293
318The block will be called for every message received on the port. When the 294The block will be called for every message received on the port, with the
319callback returns a true value its job is considered "done" and the port 295global variable C<$SELF> set to the port ID. Runtime errors will cause the
320will be destroyed. Otherwise it will stay alive. 296port to be C<kil>ed. The message will be passed as-is, no extra argument
297(i.e. no port ID) will be passed to the callback.
321 298
322The message will be passed as-is, no extra argument (i.e. no port id) will 299If you want to stop/destroy the port, simply C<kil> it:
323be passed to the callback.
324 300
325If you need the local port id in the callback, this works nicely: 301 my $port = port {
326 302 my @msg = @_;
327 my $port; $port = port { 303 ...
328 snd $otherport, reply => $port; 304 kil $SELF;
329 }; 305 };
330 306
331=cut 307=cut
332 308
333sub rcv($@); 309sub rcv($@);
310
311sub _kilme {
312 die "received message on port without callback";
313}
334 314
335sub port(;&) { 315sub port(;&) {
336 my $id = "$UNIQ." . $ID++; 316 my $id = "$UNIQ." . $ID++;
337 my $port = "$NODE#$id"; 317 my $port = "$NODE#$id";
338 318
339 if (@_) { 319 rcv $port, shift || \&_kilme;
340 rcv $port, shift;
341 } else {
342 $PORT{$id} = sub { }; # nop
343 }
344 320
345 $port 321 $port
346} 322}
347 323
348=item reg $port, $name
349
350=item reg $name
351
352Registers the given port (or C<$SELF><<< if missing) under the name
353C<$name>. If the name already exists it is replaced.
354
355A port can only be registered under one well known name.
356
357A port automatically becomes unregistered when it is killed.
358
359=cut
360
361sub reg(@) {
362 my $port = @_ > 1 ? shift : $SELF || Carp::croak 'reg: called with one argument only, but $SELF not set,';
363
364 $REG{$_[0]} = $port;
365}
366
367=item rcv $port, $callback->(@msg) 324=item rcv $local_port, $callback->(@msg)
368 325
369Replaces the callback on the specified miniport (after converting it to 326Replaces the default callback on the specified port. There is no way to
370one if required). 327remove the default callback: use C<sub { }> to disable it, or better
371 328C<kil> the port when it is no longer needed.
372=item rcv $port, tagstring => $callback->(@msg), ...
373
374=item rcv $port, $smartmatch => $callback->(@msg), ...
375
376=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
377
378Register callbacks to be called on matching messages on the given full
379port (after converting it to one if required) and return the port.
380
381The callback has to return a true value when its work is done, after
382which is will be removed, or a false value in which case it will stay
383registered.
384 329
385The global C<$SELF> (exported by this module) contains C<$port> while 330The global C<$SELF> (exported by this module) contains C<$port> while
386executing the callback. 331executing the callback. Runtime errors during callback execution will
332result in the port being C<kil>ed.
387 333
388Runtime errors during callback execution will result in the port being 334The default callback received all messages not matched by a more specific
389C<kil>ed. 335C<tag> match.
390 336
391If the match is an array reference, then it will be matched against the 337=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
392first elements of the message, otherwise only the first element is being
393matched.
394 338
395Any element in the match that is specified as C<_any_> (a function 339Register (or replace) callbacks to be called on messages starting with the
396exported by this module) matches any single element of the message. 340given tag on the given port (and return the port), or unregister it (when
341C<$callback> is C<$undef> or missing). There can only be one callback
342registered for each tag.
397 343
398While not required, it is highly recommended that the first matching 344The original message will be passed to the callback, after the first
399element is a string identifying the message. The one-string-only match is 345element (the tag) has been removed. The callback will use the same
400also the most efficient match (by far). 346environment as the default callback (see above).
401 347
402Example: create a port and bind receivers on it in one go. 348Example: create a port and bind receivers on it in one go.
403 349
404 my $port = rcv port, 350 my $port = rcv port,
405 msg1 => sub { ...; 0 }, 351 msg1 => sub { ... },
406 msg2 => sub { ...; 0 }, 352 msg2 => sub { ... },
407 ; 353 ;
408 354
409Example: create a port, bind receivers and send it in a message elsewhere 355Example: create a port, bind receivers and send it in a message elsewhere
410in one go: 356in one go:
411 357
412 snd $otherport, reply => 358 snd $otherport, reply =>
413 rcv port, 359 rcv port,
414 msg1 => sub { ...; 0 }, 360 msg1 => sub { ... },
415 ... 361 ...
416 ; 362 ;
417 363
364Example: temporarily register a rcv callback for a tag matching some port
365(e.g. for a rpc reply) and unregister it after a message was received.
366
367 rcv $port, $otherport => sub {
368 my @reply = @_;
369
370 rcv $SELF, $otherport;
371 };
372
418=cut 373=cut
419 374
420sub rcv($@) { 375sub rcv($@) {
421 my $port = shift; 376 my $port = shift;
422 my ($noderef, $portid) = split /#/, $port, 2; 377 my ($nodeid, $portid) = split /#/, $port, 2;
423 378
424 ($NODE{$noderef} || add_node $noderef) == $NODE{""} 379 $NODE{$nodeid} == $NODE{""}
425 or Carp::croak "$port: rcv can only be called on local ports, caught"; 380 or Carp::croak "$port: rcv can only be called on local ports, caught";
426 381
427 if (@_ == 1) { 382 while (@_) {
383 if (ref $_[0]) {
384 if (my $self = $PORT_DATA{$portid}) {
385 "AnyEvent::MP::Port" eq ref $self
386 or Carp::croak "$port: rcv can only be called on message matching ports, caught";
387
388 $self->[2] = shift;
389 } else {
428 my $cb = shift; 390 my $cb = shift;
429 delete $PORT_DATA{$portid};
430 $PORT{$portid} = sub { 391 $PORT{$portid} = sub {
431 local $SELF = $port; 392 local $SELF = $port;
432 eval { 393 eval { &$cb }; _self_die if $@;
433 &$cb 394 };
434 and kil $port;
435 }; 395 }
436 _self_die if $@; 396 } elsif (defined $_[0]) {
437 };
438 } else {
439 my $self = $PORT_DATA{$portid} ||= do { 397 my $self = $PORT_DATA{$portid} ||= do {
440 my $self = bless { 398 my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port";
441 id => $port,
442 }, "AnyEvent::MP::Port";
443 399
444 $PORT{$portid} = sub { 400 $PORT{$portid} = sub {
445 local $SELF = $port; 401 local $SELF = $port;
446 402
447 eval {
448 for (@{ $self->{rc0}{$_[0]} }) { 403 if (my $cb = $self->[1]{$_[0]}) {
449 $_ && &{$_->[0]} 404 shift;
450 && undef $_; 405 eval { &$cb }; _self_die if $@;
451 } 406 } else {
452
453 for (@{ $self->{rcv}{$_[0]} }) {
454 $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
455 && &{$_->[0]} 407 &{ $self->[0] };
456 && undef $_;
457 }
458
459 for (@{ $self->{any} }) {
460 $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
461 && &{$_->[0]}
462 && undef $_;
463 } 408 }
464 }; 409 };
465 _self_die if $@; 410
411 $self
466 }; 412 };
467 413
468 $self
469 };
470
471 "AnyEvent::MP::Port" eq ref $self 414 "AnyEvent::MP::Port" eq ref $self
472 or Carp::croak "$port: rcv can only be called on message matching ports, caught"; 415 or Carp::croak "$port: rcv can only be called on message matching ports, caught";
473 416
474 while (@_) {
475 my ($match, $cb) = splice @_, 0, 2; 417 my ($tag, $cb) = splice @_, 0, 2;
476 418
477 if (!ref $match) { 419 if (defined $cb) {
478 push @{ $self->{rc0}{$match} }, [$cb]; 420 $self->[1]{$tag} = $cb;
479 } elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
480 my ($type, @match) = @$match;
481 @match
482 ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
483 : push @{ $self->{rc0}{$match->[0]} }, [$cb];
484 } else { 421 } else {
485 push @{ $self->{any} }, [$cb, $match]; 422 delete $self->[1]{$tag};
486 } 423 }
487 } 424 }
488 } 425 }
489 426
490 $port 427 $port
526 $res 463 $res
527 } 464 }
528 } 465 }
529} 466}
530 467
531=item $guard = mon $port, $cb->(@reason) 468=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
532 469
533=item $guard = mon $port, $rcvport 470=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
534 471
535=item $guard = mon $port 472=item $guard = mon $port # kill $SELF when $port dies
536 473
537=item $guard = mon $port, $rcvport, @msg 474=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
538 475
539Monitor the given port and do something when the port is killed or 476Monitor the given port and do something when the port is killed or
540messages to it were lost, and optionally return a guard that can be used 477messages to it were lost, and optionally return a guard that can be used
541to stop monitoring again. 478to stop monitoring again.
542
543C<mon> effectively guarantees that, in the absence of hardware failures,
544that after starting the monitor, either all messages sent to the port
545will arrive, or the monitoring action will be invoked after possible
546message loss has been detected. No messages will be lost "in between"
547(after the first lost message no further messages will be received by the
548port). After the monitoring action was invoked, further messages might get
549delivered again.
550 479
551In the first form (callback), the callback is simply called with any 480In the first form (callback), the callback is simply called with any
552number of C<@reason> elements (no @reason means that the port was deleted 481number of C<@reason> elements (no @reason means that the port was deleted
553"normally"). Note also that I<< the callback B<must> never die >>, so use 482"normally"). Note also that I<< the callback B<must> never die >>, so use
554C<eval> if unsure. 483C<eval> if unsure.
555 484
556In the second form (another port given), the other port (C<$rcvport>) 485In the second form (another port given), the other port (C<$rcvport>)
557will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on 486will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
558"normal" kils nothing happens, while under all other conditions, the other 487"normal" kils nothing happens, while under all other conditions, the other
559port is killed with the same reason. 488port is killed with the same reason.
560 489
561The third form (kill self) is the same as the second form, except that 490The third form (kill self) is the same as the second form, except that
562C<$rvport> defaults to C<$SELF>. 491C<$rvport> defaults to C<$SELF>.
563 492
564In the last form (message), a message of the form C<@msg, @reason> will be 493In the last form (message), a message of the form C<@msg, @reason> will be
565C<snd>. 494C<snd>.
495
496Monitoring-actions are one-shot: once messages are lost (and a monitoring
497alert was raised), they are removed and will not trigger again.
566 498
567As a rule of thumb, monitoring requests should always monitor a port from 499As a rule of thumb, monitoring requests should always monitor a port from
568a local port (or callback). The reason is that kill messages might get 500a local port (or callback). The reason is that kill messages might get
569lost, just like any other message. Another less obvious reason is that 501lost, just like any other message. Another less obvious reason is that
570even monitoring requests can get lost (for exmaple, when the connection 502even monitoring requests can get lost (for example, when the connection
571to the other node goes down permanently). When monitoring a port locally 503to the other node goes down permanently). When monitoring a port locally
572these problems do not exist. 504these problems do not exist.
573 505
506C<mon> effectively guarantees that, in the absence of hardware failures,
507after starting the monitor, either all messages sent to the port will
508arrive, or the monitoring action will be invoked after possible message
509loss has been detected. No messages will be lost "in between" (after
510the first lost message no further messages will be received by the
511port). After the monitoring action was invoked, further messages might get
512delivered again.
513
514Inter-host-connection timeouts and monitoring depend on the transport
515used. The only transport currently implemented is TCP, and AnyEvent::MP
516relies on TCP to detect node-downs (this can take 10-15 minutes on a
517non-idle connection, and usually around two hours for idle conenctions).
518
519This means that monitoring is good for program errors and cleaning up
520stuff eventually, but they are no replacement for a timeout when you need
521to ensure some maximum latency.
522
574Example: call a given callback when C<$port> is killed. 523Example: call a given callback when C<$port> is killed.
575 524
576 mon $port, sub { warn "port died because of <@_>\n" }; 525 mon $port, sub { warn "port died because of <@_>\n" };
577 526
578Example: kill ourselves when C<$port> is killed abnormally. 527Example: kill ourselves when C<$port> is killed abnormally.
584 mon $port, $self => "restart"; 533 mon $port, $self => "restart";
585 534
586=cut 535=cut
587 536
588sub mon { 537sub mon {
589 my ($noderef, $port) = split /#/, shift, 2; 538 my ($nodeid, $port) = split /#/, shift, 2;
590 539
591 my $node = $NODE{$noderef} || add_node $noderef; 540 my $node = $NODE{$nodeid} || add_node $nodeid;
592 541
593 my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; 542 my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,';
594 543
595 unless (ref $cb) { 544 unless (ref $cb) {
596 if (@_) { 545 if (@_) {
616is killed, the references will be freed. 565is killed, the references will be freed.
617 566
618Optionally returns a guard that will stop the monitoring. 567Optionally returns a guard that will stop the monitoring.
619 568
620This function is useful when you create e.g. timers or other watchers and 569This function is useful when you create e.g. timers or other watchers and
621want to free them when the port gets killed: 570want to free them when the port gets killed (note the use of C<psub>):
622 571
623 $port->rcv (start => sub { 572 $port->rcv (start => sub {
624 my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { 573 my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
625 undef $timer if 0.9 < rand; 574 undef $timer if 0.9 < rand;
626 }); 575 });
627 }); 576 });
628 577
629=cut 578=cut
638 587
639=item kil $port[, @reason] 588=item kil $port[, @reason]
640 589
641Kill the specified port with the given C<@reason>. 590Kill the specified port with the given C<@reason>.
642 591
643If no C<@reason> is specified, then the port is killed "normally" (linked 592If no C<@reason> is specified, then the port is killed "normally" (ports
644ports will not be kileld, or even notified). 593monitoring other ports will not necessarily die because a port dies
594"normally").
645 595
646Otherwise, linked ports get killed with the same reason (second form of 596Otherwise, linked ports get killed with the same reason (second form of
647C<mon>, see below). 597C<mon>, see above).
648 598
649Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks 599Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
650will be reported as reason C<< die => $@ >>. 600will be reported as reason C<< die => $@ >>.
651 601
652Transport/communication errors are reported as C<< transport_error => 602Transport/communication errors are reported as C<< transport_error =>
657=item $port = spawn $node, $initfunc[, @initdata] 607=item $port = spawn $node, $initfunc[, @initdata]
658 608
659Creates a port on the node C<$node> (which can also be a port ID, in which 609Creates a port on the node C<$node> (which can also be a port ID, in which
660case it's the node where that port resides). 610case it's the node where that port resides).
661 611
662The port ID of the newly created port is return immediately, and it is 612The port ID of the newly created port is returned immediately, and it is
663permissible to immediately start sending messages or monitor the port. 613possible to immediately start sending messages or to monitor the port.
664 614
665After the port has been created, the init function is 615After the port has been created, the init function is called on the remote
666called. This function must be a fully-qualified function name 616node, in the same context as a C<rcv> callback. This function must be a
667(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main 617fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
668program, use C<::name>. 618specify a function in the main program, use C<::name>.
669 619
670If the function doesn't exist, then the node tries to C<require> 620If the function doesn't exist, then the node tries to C<require>
671the package, then the package above the package and so on (e.g. 621the package, then the package above the package and so on (e.g.
672C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function 622C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
673exists or it runs out of package names. 623exists or it runs out of package names.
674 624
675The init function is then called with the newly-created port as context 625The init function is then called with the newly-created port as context
676object (C<$SELF>) and the C<@initdata> values as arguments. 626object (C<$SELF>) and the C<@initdata> values as arguments.
677 627
678A common idiom is to pass your own port, monitor the spawned port, and 628A common idiom is to pass a local port, immediately monitor the spawned
679in the init function, monitor the original port. This two-way monitoring 629port, and in the remote init function, immediately monitor the passed
680ensures that both ports get cleaned up when there is a problem. 630local port. This two-way monitoring ensures that both ports get cleaned up
631when there is a problem.
681 632
682Example: spawn a chat server port on C<$othernode>. 633Example: spawn a chat server port on C<$othernode>.
683 634
684 # this node, executed from within a port context: 635 # this node, executed from within a port context:
685 my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; 636 my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
708 }; 659 };
709 _self_die if $@; 660 _self_die if $@;
710} 661}
711 662
712sub spawn(@) { 663sub spawn(@) {
713 my ($noderef, undef) = split /#/, shift, 2; 664 my ($nodeid, undef) = split /#/, shift, 2;
714 665
715 my $id = "$RUNIQ." . $ID++; 666 my $id = "$RUNIQ." . $ID++;
716 667
717 $_[0] =~ /::/ 668 $_[0] =~ /::/
718 or Carp::croak "spawn init function must be a fully-qualified name, caught"; 669 or Carp::croak "spawn init function must be a fully-qualified name, caught";
719 670
720 ($NODE{$noderef} || add_node $noderef) 671 snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
721 ->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
722 672
723 "$noderef#$id" 673 "$nodeid#$id"
724} 674}
725 675
726=back 676=item after $timeout, @msg
727 677
728=head1 NODE MESSAGES 678=item after $timeout, $callback
729 679
730Nodes understand the following messages sent to them. Many of them take 680Either sends the given message, or call the given callback, after the
731arguments called C<@reply>, which will simply be used to compose a reply 681specified number of seconds.
732message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
733the remaining arguments are simply the message data.
734 682
735While other messages exist, they are not public and subject to change. 683This is simply a utility function that comes in handy at times - the
684AnyEvent::MP author is not convinced of the wisdom of having it, though,
685so it may go away in the future.
736 686
737=over 4
738
739=cut 687=cut
740 688
741=item lookup => $name, @reply 689sub after($@) {
690 my ($timeout, @action) = @_;
742 691
743Replies with the port ID of the specified well-known port, or C<undef>. 692 my $t; $t = AE::timer $timeout, 0, sub {
744 693 undef $t;
745=item devnull => ... 694 ref $action[0]
746 695 ? $action[0]()
747Generic data sink/CPU heat conversion. 696 : snd @action;
748 697 };
749=item relay => $port, @msg 698}
750
751Simply forwards the message to the given port.
752
753=item eval => $string[ @reply]
754
755Evaluates the given string. If C<@reply> is given, then a message of the
756form C<@reply, $@, @evalres> is sent.
757
758Example: crash another node.
759
760 snd $othernode, eval => "exit";
761
762=item time => @reply
763
764Replies the the current node time to C<@reply>.
765
766Example: tell the current node to send the current time to C<$myport> in a
767C<timereply> message.
768
769 snd $NODE, time => $myport, timereply => 1, 2;
770 # => snd $myport, timereply => 1, 2, <time>
771 699
772=back 700=back
773 701
774=head1 AnyEvent::MP vs. Distributed Erlang 702=head1 AnyEvent::MP vs. Distributed Erlang
775 703
785 713
786Despite the similarities, there are also some important differences: 714Despite the similarities, there are also some important differences:
787 715
788=over 4 716=over 4
789 717
790=item * Node references contain the recipe on how to contact them. 718=item * Node IDs are arbitrary strings in AEMP.
791 719
792Erlang relies on special naming and DNS to work everywhere in the 720Erlang relies on special naming and DNS to work everywhere in the same
793same way. AEMP relies on each node knowing it's own address(es), with 721way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
794convenience functionality. 722configuration or DNS), but will otherwise discover other odes itself.
795 723
796This means that AEMP requires a less tightly controlled environment at the 724=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
797cost of longer node references and a slightly higher management overhead. 725uses "local ports are like remote ports".
726
727The failure modes for local ports are quite different (runtime errors
728only) then for remote ports - when a local port dies, you I<know> it dies,
729when a connection to another node dies, you know nothing about the other
730port.
731
732Erlang pretends remote ports are as reliable as local ports, even when
733they are not.
734
735AEMP encourages a "treat remote ports differently" philosophy, with local
736ports being the special case/exception, where transport errors cannot
737occur.
798 738
799=item * Erlang uses processes and a mailbox, AEMP does not queue. 739=item * Erlang uses processes and a mailbox, AEMP does not queue.
800 740
801Erlang uses processes that selctively receive messages, and therefore 741Erlang uses processes that selectively receive messages, and therefore
802needs a queue. AEMP is event based, queuing messages would serve no useful 742needs a queue. AEMP is event based, queuing messages would serve no
803purpose. 743useful purpose. For the same reason the pattern-matching abilities of
744AnyEvent::MP are more limited, as there is little need to be able to
745filter messages without dequeuing them.
804 746
805(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). 747(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
806 748
807=item * Erlang sends are synchronous, AEMP sends are asynchronous. 749=item * Erlang sends are synchronous, AEMP sends are asynchronous.
808 750
809Sending messages in Erlang is synchronous and blocks the process. AEMP 751Sending messages in Erlang is synchronous and blocks the process (and
810sends are immediate, connection establishment is handled in the 752so does not need a queue that can overflow). AEMP sends are immediate,
811background. 753connection establishment is handled in the background.
812 754
813=item * Erlang can silently lose messages, AEMP cannot. 755=item * Erlang suffers from silent message loss, AEMP does not.
814 756
815Erlang makes few guarantees on messages delivery - messages can get lost 757Erlang makes few guarantees on messages delivery - messages can get lost
816without any of the processes realising it (i.e. you send messages a, b, 758without any of the processes realising it (i.e. you send messages a, b,
817and c, and the other side only receives messages a and c). 759and c, and the other side only receives messages a and c).
818 760
819AEMP guarantees correct ordering, and the guarantee that there are no 761AEMP guarantees correct ordering, and the guarantee that after one message
820holes in the message sequence. 762is lost, all following ones sent to the same port are lost as well, until
821 763monitoring raises an error, so there are no silent "holes" in the message
822=item * In Erlang, processes can be declared dead and later be found to be 764sequence.
823alive.
824
825In Erlang it can happen that a monitored process is declared dead and
826linked processes get killed, but later it turns out that the process is
827still alive - and can receive messages.
828
829In AEMP, when port monitoring detects a port as dead, then that port will
830eventually be killed - it cannot happen that a node detects a port as dead
831and then later sends messages to it, finding it is still alive.
832 765
833=item * Erlang can send messages to the wrong port, AEMP does not. 766=item * Erlang can send messages to the wrong port, AEMP does not.
834 767
835In Erlang it is quite possible that a node that restarts reuses a process 768In Erlang it is quite likely that a node that restarts reuses a process ID
836ID known to other nodes for a completely different process, causing 769known to other nodes for a completely different process, causing messages
837messages destined for that process to end up in an unrelated process. 770destined for that process to end up in an unrelated process.
838 771
839AEMP never reuses port IDs, so old messages or old port IDs floating 772AEMP never reuses port IDs, so old messages or old port IDs floating
840around in the network will not be sent to an unrelated port. 773around in the network will not be sent to an unrelated port.
841 774
842=item * Erlang uses unprotected connections, AEMP uses secure 775=item * Erlang uses unprotected connections, AEMP uses secure
843authentication and can use TLS. 776authentication and can use TLS.
844 777
845AEMP can use a proven protocol - SSL/TLS - to protect connections and 778AEMP can use a proven protocol - TLS - to protect connections and
846securely authenticate nodes. 779securely authenticate nodes.
847 780
848=item * The AEMP protocol is optimised for both text-based and binary 781=item * The AEMP protocol is optimised for both text-based and binary
849communications. 782communications.
850 783
851The AEMP protocol, unlike the Erlang protocol, supports both 784The AEMP protocol, unlike the Erlang protocol, supports both programming
852language-independent text-only protocols (good for debugging) and binary, 785language independent text-only protocols (good for debugging) and binary,
853language-specific serialisers (e.g. Storable). 786language-specific serialisers (e.g. Storable). By default, unless TLS is
787used, the protocol is actually completely text-based.
854 788
855It has also been carefully designed to be implementable in other languages 789It has also been carefully designed to be implementable in other languages
856with a minimum of work while gracefully degrading fucntionality to make the 790with a minimum of work while gracefully degrading functionality to make the
857protocol simple. 791protocol simple.
858 792
859=item * AEMP has more flexible monitoring options than Erlang. 793=item * AEMP has more flexible monitoring options than Erlang.
860 794
861In Erlang, you can chose to receive I<all> exit signals as messages 795In Erlang, you can chose to receive I<all> exit signals as messages
864Erlang, as one can choose between automatic kill, exit message or callback 798Erlang, as one can choose between automatic kill, exit message or callback
865on a per-process basis. 799on a per-process basis.
866 800
867=item * Erlang tries to hide remote/local connections, AEMP does not. 801=item * Erlang tries to hide remote/local connections, AEMP does not.
868 802
869Monitoring in Erlang is not an indicator of process death/crashes, 803Monitoring in Erlang is not an indicator of process death/crashes, in the
870as linking is (except linking is unreliable in Erlang). 804same way as linking is (except linking is unreliable in Erlang).
871 805
872In AEMP, you don't "look up" registered port names or send to named ports 806In AEMP, you don't "look up" registered port names or send to named ports
873that might or might not be persistent. Instead, you normally spawn a port 807that might or might not be persistent. Instead, you normally spawn a port
874on the remote node. The init function monitors the you, and you monitor 808on the remote node. The init function monitors you, and you monitor the
875the remote port. Since both monitors are local to the node, they are much 809remote port. Since both monitors are local to the node, they are much more
876more reliable. 810reliable (no need for C<spawn_link>).
877 811
878This also saves round-trips and avoids sending messages to the wrong port 812This also saves round-trips and avoids sending messages to the wrong port
879(hard to do in Erlang). 813(hard to do in Erlang).
880 814
881=back 815=back
882 816
883=head1 RATIONALE 817=head1 RATIONALE
884 818
885=over 4 819=over 4
886 820
887=item Why strings for ports and noderefs, why not objects? 821=item Why strings for port and node IDs, why not objects?
888 822
889We considered "objects", but found that the actual number of methods 823We considered "objects", but found that the actual number of methods
890thatc an be called are very low. Since port IDs and noderefs travel over 824that can be called are quite low. Since port and node IDs travel over
891the network frequently, the serialising/deserialising would add lots of 825the network frequently, the serialising/deserialising would add lots of
892overhead, as well as having to keep a proxy object. 826overhead, as well as having to keep a proxy object everywhere.
893 827
894Strings can easily be printed, easily serialised etc. and need no special 828Strings can easily be printed, easily serialised etc. and need no special
895procedures to be "valid". 829procedures to be "valid".
896 830
897And a a miniport consists of a single closure stored in a global hash - it 831And as a result, a miniport consists of a single closure stored in a
898can't become much cheaper. 832global hash - it can't become much cheaper.
899 833
900=item Why favour JSON, why not real serialising format such as Storable? 834=item Why favour JSON, why not a real serialising format such as Storable?
901 835
902In fact, any AnyEvent::MP node will happily accept Storable as framing 836In fact, any AnyEvent::MP node will happily accept Storable as framing
903format, but currently there is no way to make a node use Storable by 837format, but currently there is no way to make a node use Storable by
904default. 838default (although all nodes will accept it).
905 839
906The default framing protocol is JSON because a) JSON::XS is many times 840The default framing protocol is JSON because a) JSON::XS is many times
907faster for small messages and b) most importantly, after years of 841faster for small messages and b) most importantly, after years of
908experience we found that object serialisation is causing more problems 842experience we found that object serialisation is causing more problems
909than it gains: Just like function calls, objects simply do not travel 843than it solves: Just like function calls, objects simply do not travel
910easily over the network, mostly because they will always be a copy, so you 844easily over the network, mostly because they will always be a copy, so you
911always have to re-think your design. 845always have to re-think your design.
912 846
913Keeping your messages simple, concentrating on data structures rather than 847Keeping your messages simple, concentrating on data structures rather than
914objects, will keep your messages clean, tidy and efficient. 848objects, will keep your messages clean, tidy and efficient.
915 849
916=back 850=back
917 851
918=head1 SEE ALSO 852=head1 SEE ALSO
919 853
854L<AnyEvent::MP::Intro> - a gentle introduction.
855
856L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
857
858L<AnyEvent::MP::Global> - network maintainance and port groups, to find
859your applications.
860
920L<AnyEvent>. 861L<AnyEvent>.
921 862
922=head1 AUTHOR 863=head1 AUTHOR
923 864
924 Marc Lehmann <schmorp@schmorp.de> 865 Marc Lehmann <schmorp@schmorp.de>

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