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Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.87 by root, Fri Sep 11 02:32:23 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
12 $SELF # receiving/own port id in rcv callbacks
13
14 # initialise the node so it can send/receive messages
15 configure;
16
17 # ports are message destinations
18
19 # sending messages
13 snd $port, type => data...; 20 snd $port, type => data...;
21 snd $port, @msg;
22 snd @msg_with_first_element_being_a_port;
14 23
15 $SELF # receiving/own port id in rcv callbacks 24 # creating/using ports, the simple way
25 my $simple_port = port { my @msg = @_ };
16 26
17 rcv $port, smartmatch => $cb->($port, @msg); 27 # creating/using ports, tagged message matching
18 28 my $port = port;
19 # examples:
20 rcv $port2, ping => sub { snd $_[0], "pong"; 0 }; 29 rcv $port, ping => sub { snd $_[0], "pong" };
21 rcv $port1, pong => sub { warn "pong received\n" }; 30 rcv $port, pong => sub { warn "pong received\n" };
22 snd $port2, ping => $port1;
23 31
24 # more, smarter, matches (_any_ is exported by this module) 32 # create a port on another node
25 rcv $port, [child_died => $pid] => sub { ... 33 my $port = spawn $node, $initfunc, @initdata;
26 rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27 34
28 # monitoring 35 # monitoring
29 mon $port, $cb->(@msg) # callback is invoked on death 36 mon $port, $cb->(@msg) # callback is invoked on death
30 mon $port, $otherport # kill otherport on abnormal death 37 mon $port, $otherport # kill otherport on abnormal death
31 mon $port, $otherport, @msg # send message on death 38 mon $port, $otherport, @msg # send message on death
32 39
40=head1 CURRENT STATUS
41
42 bin/aemp - stable.
43 AnyEvent::MP - stable API, should work.
44 AnyEvent::MP::Intro - explains most concepts.
45 AnyEvent::MP::Kernel - mostly stable.
46 AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
47
48stay tuned.
49
33=head1 DESCRIPTION 50=head1 DESCRIPTION
34 51
35This module (-family) implements a simple message passing framework. 52This module (-family) implements a simple message passing framework.
36 53
37Despite its simplicity, you can securely message other processes running 54Despite its simplicity, you can securely message other processes running
38on the same or other hosts. 55on the same or other hosts, and you can supervise entities remotely.
39 56
40For 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>
41manual page. 58manual page and the examples under F<eg/>.
42
43At the moment, this module family is severly broken and underdocumented,
44so do not use. This was uploaded mainly to reserve the CPAN namespace -
45stay tuned! The basic API should be finished, however.
46 59
47=head1 CONCEPTS 60=head1 CONCEPTS
48 61
49=over 4 62=over 4
50 63
51=item port 64=item port
52 65
53A 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).
54 68
55Some 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
56messages. All C<rcv> handlers will receive messages they match, messages 70some messages. Messages send to ports will not be queued, regardless of
57will not be queued. 71anything was listening for them or not.
58 72
59=item port id - C<noderef#portname> 73=item port ID - C<nodeid#portname>
60 74
61A 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
62separator, and a port name (a printable string of unspecified format). An 76separator, and a port name (a printable string of unspecified format).
63exception is the the node port, whose ID is identical to its node
64reference.
65 77
66=item node 78=item node
67 79
68A 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,
69port. 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
70create new ports, among other things. 82ports.
71 83
72Nodes are either private (single-process only), slaves (connected to a 84Nodes are either public (have one or more listening ports) or private
73master node only) or public nodes (connectable from unrelated nodes). 85(no listening ports). Private nodes cannot talk to other private nodes
86currently.
74 87
75=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> 88=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
76 89
77A 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
78private 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
79node (for public nodes). 92hostname, a hostname and a port, or a random string. AnyEvent::MP itself
93doesn't interpret node IDs in any way.
80 94
81This recipe is simply a comma-separated list of C<address:port> pairs (for 95=item binds - C<ip:port>
82TCP/IP, other protocols might look different).
83 96
84Node references come in two flavours: resolved (containing only numerical 97Nodes can only talk to each other by creating some kind of connection to
85addresses) 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.
86 101
87Before using an unresolved node reference in a message you first have to 102=item seed nodes
88resolve 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
108Apart from the fact that other nodes know them as seed nodes and they have
109to have fixed listening addresses, seed nodes are perfectly normal nodes -
110any node can function as a seed node for others.
111
112In addition to discovering the network, seed nodes are also used to
113maintain the network and to connect nodes that otherwise would have
114trouble connecting. They form the backbone of an AnyEvent::MP network.
115
116Seed nodes are expected to be long-running, and at least one seed node
117should always be available. They should also be relatively responsive - a
118seed node that blocks for long periods will slow down everybody else.
119
120=item seeds - C<host:port>
121
122Seeds are transport endpoint(s) (usually a hostname/IP address and a
123TCP port) of nodes thta should be used as seed nodes.
124
125The nodes listening on those endpoints are expected to be long-running,
126and at least one of those should always be available. When nodes run out
127of connections (e.g. due to a network error), they try to re-establish
128connections to some seednodes again to join the network.
89 129
90=back 130=back
91 131
92=head1 VARIABLES/FUNCTIONS 132=head1 VARIABLES/FUNCTIONS
93 133
95 135
96=cut 136=cut
97 137
98package AnyEvent::MP; 138package AnyEvent::MP;
99 139
100use AnyEvent::MP::Base; 140use AnyEvent::MP::Kernel;
101 141
102use common::sense; 142use common::sense;
103 143
104use Carp (); 144use Carp ();
105 145
106use AE (); 146use AE ();
107 147
108use base "Exporter"; 148use base "Exporter";
109 149
110our $VERSION = '0.1'; 150our $VERSION = $AnyEvent::MP::Kernel::VERSION;
151
111our @EXPORT = qw( 152our @EXPORT = qw(
112 NODE $NODE *SELF node_of _any_ 153 NODE $NODE *SELF node_of after
113 resolve_node initialise_node 154 configure
114 snd rcv mon kil reg psub 155 snd rcv mon mon_guard kil reg psub spawn cal
115 port 156 port
116); 157);
117 158
118our $SELF; 159our $SELF;
119 160
123 kil $SELF, die => $msg; 164 kil $SELF, die => $msg;
124} 165}
125 166
126=item $thisnode = NODE / $NODE 167=item $thisnode = NODE / $NODE
127 168
128The C<NODE> function returns, and the C<$NODE> variable contains 169The C<NODE> function returns, and the C<$NODE> variable contains, the node
129the noderef of the local node. The value is initialised by a call 170ID of the node running in the current process. This value is initialised by
130to C<become_public> or C<become_slave>, after which all local port 171a call to C<configure>.
131identifiers become invalid.
132 172
133=item $noderef = node_of $port 173=item $nodeid = node_of $port
134 174
135Extracts and returns the noderef from a portid or a noderef. 175Extracts and returns the node ID from a port ID or a node ID.
136 176
137=item initialise_node $noderef, $seednode, $seednode... 177=item configure $profile, key => value...
138 178
139=item initialise_node "slave/", $master, $master... 179=item configure key => value...
140 180
141Before a node can talk to other nodes on the network it has to initialise 181Before a node can talk to other nodes on the network (i.e. enter
142itself - the minimum a node needs to know is it's own name, and optionally 182"distributed mode") it has to configure itself - the minimum a node needs
143it should know the noderefs of some other nodes in the network. 183to know is its own name, and optionally it should know the addresses of
184some other nodes in the network to discover other nodes.
144 185
145This function initialises a node - it must be called exactly once (or 186This function configures a node - it must be called exactly once (or
146never) before calling other AnyEvent::MP functions. 187never) before calling other AnyEvent::MP functions.
147 188
148All arguments are noderefs, which can be either resolved or unresolved.
149
150There are two types of networked nodes, public nodes and slave nodes:
151
152=over 4 189=over 4
153 190
154=item public nodes 191=item step 1, gathering configuration from profiles
155 192
156For public nodes, C<$noderef> must either be a (possibly unresolved) 193The function first looks up a profile in the aemp configuration (see the
157noderef, in which case it will be resolved, or C<undef> (or missing), in 194L<aemp> commandline utility). The profile name can be specified via the
158which case the noderef will be guessed. 195named C<profile> parameter or can simply be the first parameter). If it is
196missing, then the nodename (F<uname -n>) will be used as profile name.
159 197
160Afterwards, the node will bind itself on all endpoints and try to connect 198The profile data is then gathered as follows:
161to all additional C<$seednodes> that are specified. Seednodes are optional
162and can be used to quickly bootstrap the node into an existing network.
163 199
164=item slave nodes 200First, all remaining key => value pairs (all of which are conveniently
201undocumented at the moment) will be interpreted as configuration
202data. Then they will be overwritten by any values specified in the global
203default configuration (see the F<aemp> utility), then the chain of
204profiles chosen by the profile name (and any C<parent> attributes).
165 205
166When the C<$noderef> is the special string C<slave/>, then the node will 206That means that the values specified in the profile have highest priority
167become a slave node. Slave nodes cannot be contacted from outside and will 207and the values specified directly via C<configure> have lowest priority,
168route most of their traffic to the master node that they attach to. 208and can only be used to specify defaults.
169 209
170At least one additional noderef is required: The node will try to connect 210If the profile specifies a node ID, then this will become the node ID of
171to all of them and will become a slave attached to the first node it can 211this process. If not, then the profile name will be used as node ID. The
172successfully connect to. 212special node ID of C<anon/> will be replaced by a random node ID.
213
214=item step 2, bind listener sockets
215
216The next step is to look up the binds in the profile, followed by binding
217aemp protocol listeners on all binds specified (it is possible and valid
218to have no binds, meaning that the node cannot be contacted form the
219outside. This means the node cannot talk to other nodes that also have no
220binds, but it can still talk to all "normal" nodes).
221
222If the profile does not specify a binds list, then a default of C<*> is
223used, meaning the node will bind on a dynamically-assigned port on every
224local IP address it finds.
225
226=item step 3, connect to seed nodes
227
228As the last step, the seeds list from the profile is passed to the
229L<AnyEvent::MP::Global> module, which will then use it to keep
230connectivity with at least one node at any point in time.
173 231
174=back 232=back
175 233
176This function will block until all nodes have been resolved and, for slave 234Example: become a distributed node using the local node name as profile.
177nodes, until it has successfully established a connection to a master 235This should be the most common form of invocation for "daemon"-type nodes.
178server.
179 236
180Example: become a public node listening on the default node. 237 configure
181 238
182 initialise_node; 239Example: become an anonymous node. This form is often used for commandline
240clients.
183 241
184Example: become a public node, and try to contact some well-known master 242 configure nodeid => "anon/";
185servers to become part of the network.
186 243
187 initialise_node undef, "master1", "master2"; 244Example: configure a node using a profile called seed, which si suitable
245for a seed node as it binds on all local addresses on a fixed port (4040,
246customary for aemp).
188 247
189Example: become a public node listening on port C<4041>. 248 # use the aemp commandline utility
249 # aemp profile seed nodeid anon/ binds '*:4040'
190 250
191 initialise_node 4041; 251 # then use it
252 configure profile => "seed";
192 253
193Example: become a public node, only visible on localhost port 4044. 254 # or simply use aemp from the shell again:
255 # aemp run profile seed
194 256
195 initialise_node "locahost:4044"; 257 # or provide a nicer-to-remember nodeid
196 258 # aemp run profile seed nodeid "$(hostname)"
197Example: become a slave node to any of the specified master servers.
198
199 initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
200
201=item $cv = resolve_node $noderef
202
203Takes an unresolved node reference that may contain hostnames and
204abbreviated IDs, resolves all of them and returns a resolved node
205reference.
206
207In addition to C<address:port> pairs allowed in resolved noderefs, the
208following forms are supported:
209
210=over 4
211
212=item the empty string
213
214An empty-string component gets resolved as if the default port (4040) was
215specified.
216
217=item naked port numbers (e.g. C<1234>)
218
219These are resolved by prepending the local nodename and a colon, to be
220further resolved.
221
222=item hostnames (e.g. C<localhost:1234>, C<localhost>)
223
224These are resolved by using AnyEvent::DNS to resolve them, optionally
225looking up SRV records for the C<aemp=4040> port, if no port was
226specified.
227
228=back
229 259
230=item $SELF 260=item $SELF
231 261
232Contains the current port id while executing C<rcv> callbacks or C<psub> 262Contains the current port id while executing C<rcv> callbacks or C<psub>
233blocks. 263blocks.
234 264
235=item SELF, %SELF, @SELF... 265=item *SELF, SELF, %SELF, @SELF...
236 266
237Due to some quirks in how perl exports variables, it is impossible to 267Due to some quirks in how perl exports variables, it is impossible to
238just export C<$SELF>, all the symbols called C<SELF> are exported by this 268just export C<$SELF>, all the symbols named C<SELF> are exported by this
239module, but only C<$SELF> is currently used. 269module, but only C<$SELF> is currently used.
240 270
241=item snd $port, type => @data 271=item snd $port, type => @data
242 272
243=item snd $port, @msg 273=item snd $port, @msg
244 274
245Send the given message to the given port ID, which can identify either 275Send the given message to the given port, which can identify either a
246a local or a remote port, and can be either a string or soemthignt hat 276local or a remote port, and must be a port ID.
247stringifies a sa port ID (such as a port object :).
248 277
249While the message can be about anything, it is highly recommended to use a 278While the message can be almost anything, it is highly recommended to
250string as first element (a portid, or some word that indicates a request 279use a string as first element (a port ID, or some word that indicates a
251type etc.). 280request type etc.) and to consist if only simple perl values (scalars,
281arrays, hashes) - if you think you need to pass an object, think again.
252 282
253The message data effectively becomes read-only after a call to this 283The message data logically becomes read-only after a call to this
254function: modifying any argument is not allowed and can cause many 284function: modifying any argument (or values referenced by them) is
255problems. 285forbidden, as there can be considerable time between the call to C<snd>
286and the time the message is actually being serialised - in fact, it might
287never be copied as within the same process it is simply handed to the
288receiving port.
256 289
257The type of data you can transfer depends on the transport protocol: when 290The type of data you can transfer depends on the transport protocol: when
258JSON is used, then only strings, numbers and arrays and hashes consisting 291JSON is used, then only strings, numbers and arrays and hashes consisting
259of those are allowed (no objects). When Storable is used, then anything 292of those are allowed (no objects). When Storable is used, then anything
260that Storable can serialise and deserialise is allowed, and for the local 293that Storable can serialise and deserialise is allowed, and for the local
261node, anything can be passed. 294node, anything can be passed. Best rely only on the common denominator of
295these.
262 296
263=item $local_port = port 297=item $local_port = port
264 298
265Create a new local port object that can be used either as a pattern 299Create a new local port object and returns its port ID. Initially it has
266matching port ("full port") or a single-callback port ("miniport"), 300no callbacks set and will throw an error when it receives messages.
267depending on how C<rcv> callbacks are bound to the object.
268 301
269=item $port = port { my @msg = @_; $finished } 302=item $local_port = port { my @msg = @_ }
270 303
271Creates a "miniport", that is, a very lightweight port without any pattern 304Creates a new local port, and returns its ID. Semantically the same as
272matching behind it, and returns its ID. Semantically the same as creating
273a port and calling C<rcv $port, $callback> on it. 305creating a port and calling C<rcv $port, $callback> on it.
274 306
275The block will be called for every message received on the port. When the 307The block will be called for every message received on the port, with the
276callback returns a true value its job is considered "done" and the port 308global variable C<$SELF> set to the port ID. Runtime errors will cause the
277will be destroyed. Otherwise it will stay alive. 309port to be C<kil>ed. The message will be passed as-is, no extra argument
310(i.e. no port ID) will be passed to the callback.
278 311
279The message will be passed as-is, no extra argument (i.e. no port id) will 312If you want to stop/destroy the port, simply C<kil> it:
280be passed to the callback.
281 313
282If you need the local port id in the callback, this works nicely: 314 my $port = port {
283 315 my @msg = @_;
284 my $port; $port = port { 316 ...
285 snd $otherport, reply => $port; 317 kil $SELF;
286 }; 318 };
287 319
288=cut 320=cut
289 321
290sub rcv($@); 322sub rcv($@);
323
324sub _kilme {
325 die "received message on port without callback";
326}
291 327
292sub port(;&) { 328sub port(;&) {
293 my $id = "$UNIQ." . $ID++; 329 my $id = "$UNIQ." . $ID++;
294 my $port = "$NODE#$id"; 330 my $port = "$NODE#$id";
295 331
296 if (@_) { 332 rcv $port, shift || \&_kilme;
297 rcv $port, shift;
298 } else {
299 $PORT{$id} = sub { }; # nop
300 }
301 333
302 $port 334 $port
303} 335}
304 336
305=item reg $port, $name
306
307=item reg $name
308
309Registers the given port (or C<$SELF><<< if missing) under the name
310C<$name>. If the name already exists it is replaced.
311
312A port can only be registered under one well known name.
313
314A port automatically becomes unregistered when it is killed.
315
316=cut
317
318sub reg(@) {
319 my $port = @_ > 1 ? shift : $SELF || Carp::croak 'reg: called with one argument only, but $SELF not set,';
320
321 $REG{$_[0]} = $port;
322}
323
324=item rcv $port, $callback->(@msg) 337=item rcv $local_port, $callback->(@msg)
325 338
326Replaces the callback on the specified miniport (after converting it to 339Replaces the default callback on the specified port. There is no way to
327one if required). 340remove the default callback: use C<sub { }> to disable it, or better
328 341C<kil> the port when it is no longer needed.
329=item rcv $port, tagstring => $callback->(@msg), ...
330
331=item rcv $port, $smartmatch => $callback->(@msg), ...
332
333=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
334
335Register callbacks to be called on matching messages on the given full
336port (after converting it to one if required) and return the port.
337
338The callback has to return a true value when its work is done, after
339which is will be removed, or a false value in which case it will stay
340registered.
341 342
342The global C<$SELF> (exported by this module) contains C<$port> while 343The global C<$SELF> (exported by this module) contains C<$port> while
343executing the callback. 344executing the callback. Runtime errors during callback execution will
345result in the port being C<kil>ed.
344 346
345Runtime errors wdurign callback execution will result in the port being 347The default callback received all messages not matched by a more specific
346C<kil>ed. 348C<tag> match.
347 349
348If the match is an array reference, then it will be matched against the 350=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349first elements of the message, otherwise only the first element is being
350matched.
351 351
352Any element in the match that is specified as C<_any_> (a function 352Register (or replace) callbacks to be called on messages starting with the
353exported by this module) matches any single element of the message. 353given tag on the given port (and return the port), or unregister it (when
354C<$callback> is C<$undef> or missing). There can only be one callback
355registered for each tag.
354 356
355While not required, it is highly recommended that the first matching 357The original message will be passed to the callback, after the first
356element is a string identifying the message. The one-string-only match is 358element (the tag) has been removed. The callback will use the same
357also the most efficient match (by far). 359environment as the default callback (see above).
358 360
359Example: create a port and bind receivers on it in one go. 361Example: create a port and bind receivers on it in one go.
360 362
361 my $port = rcv port, 363 my $port = rcv port,
362 msg1 => sub { ...; 0 }, 364 msg1 => sub { ... },
363 msg2 => sub { ...; 0 }, 365 msg2 => sub { ... },
364 ; 366 ;
365 367
366Example: create a port, bind receivers and send it in a message elsewhere 368Example: create a port, bind receivers and send it in a message elsewhere
367in one go: 369in one go:
368 370
369 snd $otherport, reply => 371 snd $otherport, reply =>
370 rcv port, 372 rcv port,
371 msg1 => sub { ...; 0 }, 373 msg1 => sub { ... },
372 ... 374 ...
373 ; 375 ;
374 376
377Example: temporarily register a rcv callback for a tag matching some port
378(e.g. for a rpc reply) and unregister it after a message was received.
379
380 rcv $port, $otherport => sub {
381 my @reply = @_;
382
383 rcv $SELF, $otherport;
384 };
385
375=cut 386=cut
376 387
377sub rcv($@) { 388sub rcv($@) {
378 my $port = shift; 389 my $port = shift;
379 my ($noderef, $portid) = split /#/, $port, 2; 390 my ($nodeid, $portid) = split /#/, $port, 2;
380 391
381 ($NODE{$noderef} || add_node $noderef) == $NODE{""} 392 $NODE{$nodeid} == $NODE{""}
382 or Carp::croak "$port: rcv can only be called on local ports, caught"; 393 or Carp::croak "$port: rcv can only be called on local ports, caught";
383 394
384 if (@_ == 1) { 395 while (@_) {
396 if (ref $_[0]) {
397 if (my $self = $PORT_DATA{$portid}) {
398 "AnyEvent::MP::Port" eq ref $self
399 or Carp::croak "$port: rcv can only be called on message matching ports, caught";
400
401 $self->[2] = shift;
402 } else {
385 my $cb = shift; 403 my $cb = shift;
386 delete $PORT_DATA{$portid};
387 $PORT{$portid} = sub { 404 $PORT{$portid} = sub {
388 local $SELF = $port; 405 local $SELF = $port;
389 eval { 406 eval { &$cb }; _self_die if $@;
390 &$cb 407 };
391 and kil $port;
392 }; 408 }
393 _self_die if $@; 409 } elsif (defined $_[0]) {
394 };
395 } else {
396 my $self = $PORT_DATA{$portid} ||= do { 410 my $self = $PORT_DATA{$portid} ||= do {
397 my $self = bless { 411 my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port";
398 id => $port,
399 }, "AnyEvent::MP::Port";
400 412
401 $PORT{$portid} = sub { 413 $PORT{$portid} = sub {
402 local $SELF = $port; 414 local $SELF = $port;
403 415
404 eval {
405 for (@{ $self->{rc0}{$_[0]} }) { 416 if (my $cb = $self->[1]{$_[0]}) {
406 $_ && &{$_->[0]} 417 shift;
407 && undef $_; 418 eval { &$cb }; _self_die if $@;
408 } 419 } else {
409
410 for (@{ $self->{rcv}{$_[0]} }) {
411 $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412 && &{$_->[0]} 420 &{ $self->[0] };
413 && undef $_;
414 }
415
416 for (@{ $self->{any} }) {
417 $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418 && &{$_->[0]}
419 && undef $_;
420 } 421 }
421 }; 422 };
422 _self_die if $@; 423
424 $self
423 }; 425 };
424 426
425 $self
426 };
427
428 "AnyEvent::MP::Port" eq ref $self 427 "AnyEvent::MP::Port" eq ref $self
429 or Carp::croak "$port: rcv can only be called on message matching ports, caught"; 428 or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430 429
431 while (@_) {
432 my ($match, $cb) = splice @_, 0, 2; 430 my ($tag, $cb) = splice @_, 0, 2;
433 431
434 if (!ref $match) { 432 if (defined $cb) {
435 push @{ $self->{rc0}{$match} }, [$cb]; 433 $self->[1]{$tag} = $cb;
436 } elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
437 my ($type, @match) = @$match;
438 @match
439 ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
440 : push @{ $self->{rc0}{$match->[0]} }, [$cb];
441 } else { 434 } else {
442 push @{ $self->{any} }, [$cb, $match]; 435 delete $self->[1]{$tag};
443 } 436 }
444 } 437 }
445 } 438 }
446 439
447 $port 440 $port
483 $res 476 $res
484 } 477 }
485 } 478 }
486} 479}
487 480
488=item $guard = mon $port, $cb->(@reason) 481=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
489 482
490=item $guard = mon $port, $rcvport 483=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
491 484
492=item $guard = mon $port 485=item $guard = mon $port # kill $SELF when $port dies
493 486
494=item $guard = mon $port, $rcvport, @msg 487=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
495 488
496Monitor the given port and do something when the port is killed, and 489Monitor the given port and do something when the port is killed or
497optionally return a guard that can be used to stop monitoring again. 490messages to it were lost, and optionally return a guard that can be used
491to stop monitoring again.
498 492
499In the first form (callback), the callback is simply called with any 493In the first form (callback), the callback is simply called with any
500number of C<@reason> elements (no @reason means that the port was deleted 494number of C<@reason> elements (no @reason means that the port was deleted
501"normally"). Note also that I<< the callback B<must> never die >>, so use 495"normally"). Note also that I<< the callback B<must> never die >>, so use
502C<eval> if unsure. 496C<eval> if unsure.
503 497
504In the second form (another port given), the other port (C<$rcvport) 498In the second form (another port given), the other port (C<$rcvport>)
505will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on 499will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
506"normal" kils nothing happens, while under all other conditions, the other 500"normal" kils nothing happens, while under all other conditions, the other
507port is killed with the same reason. 501port is killed with the same reason.
508 502
509The third form (kill self) is the same as the second form, except that 503The third form (kill self) is the same as the second form, except that
510C<$rvport> defaults to C<$SELF>. 504C<$rvport> defaults to C<$SELF>.
511 505
512In the last form (message), a message of the form C<@msg, @reason> will be 506In the last form (message), a message of the form C<@msg, @reason> will be
513C<snd>. 507C<snd>.
508
509Monitoring-actions are one-shot: once messages are lost (and a monitoring
510alert was raised), they are removed and will not trigger again.
514 511
515As a rule of thumb, monitoring requests should always monitor a port from 512As a rule of thumb, monitoring requests should always monitor a port from
516a local port (or callback). The reason is that kill messages might get 513a local port (or callback). The reason is that kill messages might get
517lost, just like any other message. Another less obvious reason is that 514lost, just like any other message. Another less obvious reason is that
518even monitoring requests can get lost (for exmaple, when the connection 515even monitoring requests can get lost (for example, when the connection
519to the other node goes down permanently). When monitoring a port locally 516to the other node goes down permanently). When monitoring a port locally
520these problems do not exist. 517these problems do not exist.
521 518
519C<mon> effectively guarantees that, in the absence of hardware failures,
520after starting the monitor, either all messages sent to the port will
521arrive, or the monitoring action will be invoked after possible message
522loss has been detected. No messages will be lost "in between" (after
523the first lost message no further messages will be received by the
524port). After the monitoring action was invoked, further messages might get
525delivered again.
526
527Inter-host-connection timeouts and monitoring depend on the transport
528used. The only transport currently implemented is TCP, and AnyEvent::MP
529relies on TCP to detect node-downs (this can take 10-15 minutes on a
530non-idle connection, and usually around two hours for idle conenctions).
531
532This means that monitoring is good for program errors and cleaning up
533stuff eventually, but they are no replacement for a timeout when you need
534to ensure some maximum latency.
535
522Example: call a given callback when C<$port> is killed. 536Example: call a given callback when C<$port> is killed.
523 537
524 mon $port, sub { warn "port died because of <@_>\n" }; 538 mon $port, sub { warn "port died because of <@_>\n" };
525 539
526Example: kill ourselves when C<$port> is killed abnormally. 540Example: kill ourselves when C<$port> is killed abnormally.
532 mon $port, $self => "restart"; 546 mon $port, $self => "restart";
533 547
534=cut 548=cut
535 549
536sub mon { 550sub mon {
537 my ($noderef, $port) = split /#/, shift, 2; 551 my ($nodeid, $port) = split /#/, shift, 2;
538 552
539 my $node = $NODE{$noderef} || add_node $noderef; 553 my $node = $NODE{$nodeid} || add_node $nodeid;
540 554
541 my $cb = @_ ? $_[0] : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; 555 my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,';
542 556
543 unless (ref $cb) { 557 unless (ref $cb) {
544 if (@_) { 558 if (@_) {
545 # send a kill info message 559 # send a kill info message
546 my (@msg) = @_; 560 my (@msg) = ($cb, @_);
547 $cb = sub { snd @msg, @_ }; 561 $cb = sub { snd @msg, @_ };
548 } else { 562 } else {
549 # simply kill other port 563 # simply kill other port
550 my $port = $cb; 564 my $port = $cb;
551 $cb = sub { kil $port, @_ if @_ }; 565 $cb = sub { kil $port, @_ if @_ };
564is killed, the references will be freed. 578is killed, the references will be freed.
565 579
566Optionally returns a guard that will stop the monitoring. 580Optionally returns a guard that will stop the monitoring.
567 581
568This function is useful when you create e.g. timers or other watchers and 582This function is useful when you create e.g. timers or other watchers and
569want to free them when the port gets killed: 583want to free them when the port gets killed (note the use of C<psub>):
570 584
571 $port->rcv (start => sub { 585 $port->rcv (start => sub {
572 my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { 586 my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
573 undef $timer if 0.9 < rand; 587 undef $timer if 0.9 < rand;
574 }); 588 });
575 }); 589 });
576 590
577=cut 591=cut
586 600
587=item kil $port[, @reason] 601=item kil $port[, @reason]
588 602
589Kill the specified port with the given C<@reason>. 603Kill the specified port with the given C<@reason>.
590 604
591If no C<@reason> is specified, then the port is killed "normally" (linked 605If no C<@reason> is specified, then the port is killed "normally" (ports
592ports will not be kileld, or even notified). 606monitoring other ports will not necessarily die because a port dies
607"normally").
593 608
594Otherwise, linked ports get killed with the same reason (second form of 609Otherwise, linked ports get killed with the same reason (second form of
595C<mon>, see below). 610C<mon>, see above).
596 611
597Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks 612Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
598will be reported as reason C<< die => $@ >>. 613will be reported as reason C<< die => $@ >>.
599 614
600Transport/communication errors are reported as C<< transport_error => 615Transport/communication errors are reported as C<< transport_error =>
601$message >>. 616$message >>.
602 617
603=back
604
605=head1 NODE MESSAGES
606
607Nodes understand the following messages sent to them. Many of them take
608arguments called C<@reply>, which will simply be used to compose a reply
609message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
610the remaining arguments are simply the message data.
611
612While other messages exist, they are not public and subject to change.
613
614=over 4
615
616=cut 618=cut
617 619
618=item lookup => $name, @reply 620=item $port = spawn $node, $initfunc[, @initdata]
619 621
620Replies with the port ID of the specified well-known port, or C<undef>. 622Creates a port on the node C<$node> (which can also be a port ID, in which
623case it's the node where that port resides).
621 624
622=item devnull => ... 625The port ID of the newly created port is returned immediately, and it is
626possible to immediately start sending messages or to monitor the port.
623 627
624Generic data sink/CPU heat conversion. 628After the port has been created, the init function is called on the remote
629node, in the same context as a C<rcv> callback. This function must be a
630fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
631specify a function in the main program, use C<::name>.
625 632
626=item relay => $port, @msg 633If the function doesn't exist, then the node tries to C<require>
634the package, then the package above the package and so on (e.g.
635C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
636exists or it runs out of package names.
627 637
628Simply forwards the message to the given port. 638The init function is then called with the newly-created port as context
639object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
640call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
641the port might not get created.
629 642
630=item eval => $string[ @reply] 643A common idiom is to pass a local port, immediately monitor the spawned
644port, and in the remote init function, immediately monitor the passed
645local port. This two-way monitoring ensures that both ports get cleaned up
646when there is a problem.
631 647
632Evaluates the given string. If C<@reply> is given, then a message of the 648C<spawn> guarantees that the C<$initfunc> has no visible effects on the
633form C<@reply, $@, @evalres> is sent. 649caller before C<spawn> returns (by delaying invocation when spawn is
650called for the local node).
634 651
635Example: crash another node. 652Example: spawn a chat server port on C<$othernode>.
636 653
637 snd $othernode, eval => "exit"; 654 # this node, executed from within a port context:
655 my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
656 mon $server;
638 657
639=item time => @reply 658 # init function on C<$othernode>
659 sub connect {
660 my ($srcport) = @_;
640 661
641Replies the the current node time to C<@reply>. 662 mon $srcport;
642 663
643Example: tell the current node to send the current time to C<$myport> in a 664 rcv $SELF, sub {
644C<timereply> message. 665 ...
666 };
667 }
645 668
646 snd $NODE, time => $myport, timereply => 1, 2; 669=cut
647 # => snd $myport, timereply => 1, 2, <time> 670
671sub _spawn {
672 my $port = shift;
673 my $init = shift;
674
675 # rcv will create the actual port
676 local $SELF = "$NODE#$port";
677 eval {
678 &{ load_func $init }
679 };
680 _self_die if $@;
681}
682
683sub spawn(@) {
684 my ($nodeid, undef) = split /#/, shift, 2;
685
686 my $id = "$RUNIQ." . $ID++;
687
688 $_[0] =~ /::/
689 or Carp::croak "spawn init function must be a fully-qualified name, caught";
690
691 snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
692
693 "$nodeid#$id"
694}
695
696=item after $timeout, @msg
697
698=item after $timeout, $callback
699
700Either sends the given message, or call the given callback, after the
701specified number of seconds.
702
703This is simply a utility function that comes in handy at times - the
704AnyEvent::MP author is not convinced of the wisdom of having it, though,
705so it may go away in the future.
706
707=cut
708
709sub after($@) {
710 my ($timeout, @action) = @_;
711
712 my $t; $t = AE::timer $timeout, 0, sub {
713 undef $t;
714 ref $action[0]
715 ? $action[0]()
716 : snd @action;
717 };
718}
719
720=item cal $port, @msg, $callback[, $timeout]
721
722A simple form of RPC - sends a message to the given C<$port> with the
723given contents (C<@msg>), but adds a reply port to the message.
724
725The reply port is created temporarily just for the purpose of receiving
726the reply, and will be C<kil>ed when no longer needed.
727
728A reply message sent to the port is passed to the C<$callback> as-is.
729
730If an optional time-out (in seconds) is given and it is not C<undef>,
731then the callback will be called without any arguments after the time-out
732elapsed and the port is C<kil>ed.
733
734If no time-out is given, then the local port will monitor the remote port
735instead, so it eventually gets cleaned-up.
736
737Currently this function returns the temporary port, but this "feature"
738might go in future versions unless you can make a convincing case that
739this is indeed useful for something.
740
741=cut
742
743sub cal(@) {
744 my $timeout = ref $_[-1] ? undef : pop;
745 my $cb = pop;
746
747 my $port = port {
748 undef $timeout;
749 kil $SELF;
750 &$cb;
751 };
752
753 if (defined $timeout) {
754 $timeout = AE::timer $timeout, 0, sub {
755 undef $timeout;
756 kil $port;
757 $cb->();
758 };
759 } else {
760 mon $_[0], sub {
761 kil $port;
762 $cb->();
763 };
764 }
765
766 push @_, $port;
767 &snd;
768
769 $port
770}
648 771
649=back 772=back
650 773
651=head1 AnyEvent::MP vs. Distributed Erlang 774=head1 AnyEvent::MP vs. Distributed Erlang
652 775
662 785
663Despite the similarities, there are also some important differences: 786Despite the similarities, there are also some important differences:
664 787
665=over 4 788=over 4
666 789
667=item * Node references contain the recipe on how to contact them. 790=item * Node IDs are arbitrary strings in AEMP.
668 791
669Erlang relies on special naming and DNS to work everywhere in the 792Erlang relies on special naming and DNS to work everywhere in the same
670same way. AEMP relies on each node knowing it's own address(es), with 793way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
671convenience functionality. 794configuration or DNS), but will otherwise discover other odes itself.
672 795
673This means that AEMP requires a less tightly controlled environment at the 796=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
674cost of longer node references and a slightly higher management overhead. 797uses "local ports are like remote ports".
798
799The failure modes for local ports are quite different (runtime errors
800only) then for remote ports - when a local port dies, you I<know> it dies,
801when a connection to another node dies, you know nothing about the other
802port.
803
804Erlang pretends remote ports are as reliable as local ports, even when
805they are not.
806
807AEMP encourages a "treat remote ports differently" philosophy, with local
808ports being the special case/exception, where transport errors cannot
809occur.
675 810
676=item * Erlang uses processes and a mailbox, AEMP does not queue. 811=item * Erlang uses processes and a mailbox, AEMP does not queue.
677 812
678Erlang uses processes that selctively receive messages, and therefore 813Erlang uses processes that selectively receive messages, and therefore
679needs a queue. AEMP is event based, queuing messages would serve no useful 814needs a queue. AEMP is event based, queuing messages would serve no
680purpose. 815useful purpose. For the same reason the pattern-matching abilities of
816AnyEvent::MP are more limited, as there is little need to be able to
817filter messages without dequeuing them.
681 818
682(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). 819(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
683 820
684=item * Erlang sends are synchronous, AEMP sends are asynchronous. 821=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685 822
686Sending messages in Erlang is synchronous and blocks the process. AEMP 823Sending messages in Erlang is synchronous and blocks the process (and
687sends are immediate, connection establishment is handled in the 824so does not need a queue that can overflow). AEMP sends are immediate,
688background. 825connection establishment is handled in the background.
689 826
690=item * Erlang can silently lose messages, AEMP cannot. 827=item * Erlang suffers from silent message loss, AEMP does not.
691 828
692Erlang makes few guarantees on messages delivery - messages can get lost 829Erlang makes few guarantees on messages delivery - messages can get lost
693without any of the processes realising it (i.e. you send messages a, b, 830without any of the processes realising it (i.e. you send messages a, b,
694and c, and the other side only receives messages a and c). 831and c, and the other side only receives messages a and c).
695 832
696AEMP guarantees correct ordering, and the guarantee that there are no 833AEMP guarantees correct ordering, and the guarantee that after one message
697holes in the message sequence. 834is lost, all following ones sent to the same port are lost as well, until
698 835monitoring raises an error, so there are no silent "holes" in the message
699=item * In Erlang, processes can be declared dead and later be found to be 836sequence.
700alive.
701
702In Erlang it can happen that a monitored process is declared dead and
703linked processes get killed, but later it turns out that the process is
704still alive - and can receive messages.
705
706In AEMP, when port monitoring detects a port as dead, then that port will
707eventually be killed - it cannot happen that a node detects a port as dead
708and then later sends messages to it, finding it is still alive.
709 837
710=item * Erlang can send messages to the wrong port, AEMP does not. 838=item * Erlang can send messages to the wrong port, AEMP does not.
711 839
712In Erlang it is quite possible that a node that restarts reuses a process 840In Erlang it is quite likely that a node that restarts reuses a process ID
713ID known to other nodes for a completely different process, causing 841known to other nodes for a completely different process, causing messages
714messages destined for that process to end up in an unrelated process. 842destined for that process to end up in an unrelated process.
715 843
716AEMP never reuses port IDs, so old messages or old port IDs floating 844AEMP never reuses port IDs, so old messages or old port IDs floating
717around in the network will not be sent to an unrelated port. 845around in the network will not be sent to an unrelated port.
718 846
719=item * Erlang uses unprotected connections, AEMP uses secure 847=item * Erlang uses unprotected connections, AEMP uses secure
720authentication and can use TLS. 848authentication and can use TLS.
721 849
722AEMP can use a proven protocol - SSL/TLS - to protect connections and 850AEMP can use a proven protocol - TLS - to protect connections and
723securely authenticate nodes. 851securely authenticate nodes.
724 852
725=item * The AEMP protocol is optimised for both text-based and binary 853=item * The AEMP protocol is optimised for both text-based and binary
726communications. 854communications.
727 855
728The AEMP protocol, unlike the Erlang protocol, supports both 856The AEMP protocol, unlike the Erlang protocol, supports both programming
729language-independent text-only protocols (good for debugging) and binary, 857language independent text-only protocols (good for debugging) and binary,
730language-specific serialisers (e.g. Storable). 858language-specific serialisers (e.g. Storable). By default, unless TLS is
859used, the protocol is actually completely text-based.
731 860
732It has also been carefully designed to be implementable in other languages 861It has also been carefully designed to be implementable in other languages
733with a minimum of work while gracefully degrading fucntionality to make the 862with a minimum of work while gracefully degrading functionality to make the
734protocol simple. 863protocol simple.
735 864
736=item * AEMP has more flexible monitoring options than Erlang. 865=item * AEMP has more flexible monitoring options than Erlang.
737 866
738In Erlang, you can chose to receive I<all> exit signals as messages 867In Erlang, you can chose to receive I<all> exit signals as messages
741Erlang, as one can choose between automatic kill, exit message or callback 870Erlang, as one can choose between automatic kill, exit message or callback
742on a per-process basis. 871on a per-process basis.
743 872
744=item * Erlang tries to hide remote/local connections, AEMP does not. 873=item * Erlang tries to hide remote/local connections, AEMP does not.
745 874
746Monitoring in Erlang is not an indicator of process death/crashes, 875Monitoring in Erlang is not an indicator of process death/crashes, in the
747as linking is (except linking is unreliable in Erlang). 876same way as linking is (except linking is unreliable in Erlang).
748 877
749In AEMP, you don't "look up" registered port names or send to named ports 878In AEMP, you don't "look up" registered port names or send to named ports
750that might or might not be persistent. Instead, you normally spawn a port 879that might or might not be persistent. Instead, you normally spawn a port
751on the remote node. The init function monitors the you, and you monitor 880on the remote node. The init function monitors you, and you monitor the
752the remote port. Since both monitors are local to the node, they are much 881remote port. Since both monitors are local to the node, they are much more
753more reliable. 882reliable (no need for C<spawn_link>).
754 883
755This also saves round-trips and avoids sending messages to the wrong port 884This also saves round-trips and avoids sending messages to the wrong port
756(hard to do in Erlang). 885(hard to do in Erlang).
757 886
758=back 887=back
759 888
889=head1 RATIONALE
890
891=over 4
892
893=item Why strings for port and node IDs, why not objects?
894
895We considered "objects", but found that the actual number of methods
896that can be called are quite low. Since port and node IDs travel over
897the network frequently, the serialising/deserialising would add lots of
898overhead, as well as having to keep a proxy object everywhere.
899
900Strings can easily be printed, easily serialised etc. and need no special
901procedures to be "valid".
902
903And as a result, a miniport consists of a single closure stored in a
904global hash - it can't become much cheaper.
905
906=item Why favour JSON, why not a real serialising format such as Storable?
907
908In fact, any AnyEvent::MP node will happily accept Storable as framing
909format, but currently there is no way to make a node use Storable by
910default (although all nodes will accept it).
911
912The default framing protocol is JSON because a) JSON::XS is many times
913faster for small messages and b) most importantly, after years of
914experience we found that object serialisation is causing more problems
915than it solves: Just like function calls, objects simply do not travel
916easily over the network, mostly because they will always be a copy, so you
917always have to re-think your design.
918
919Keeping your messages simple, concentrating on data structures rather than
920objects, will keep your messages clean, tidy and efficient.
921
922=back
923
760=head1 SEE ALSO 924=head1 SEE ALSO
925
926L<AnyEvent::MP::Intro> - a gentle introduction.
927
928L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
929
930L<AnyEvent::MP::Global> - network maintainance and port groups, to find
931your applications.
932
933L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
934all nodes.
761 935
762L<AnyEvent>. 936L<AnyEvent>.
763 937
764=head1 AUTHOR 938=head1 AUTHOR
765 939

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