… | |
… | |
8 | |
8 | |
9 | $NODE # contains this node's noderef |
9 | $NODE # contains this node's noderef |
10 | NODE # returns this node's noderef |
10 | NODE # returns this node's noderef |
11 | NODE $port # returns the noderef of the port |
11 | NODE $port # returns the noderef of the port |
12 | |
12 | |
|
|
13 | $SELF # receiving/own port id in rcv callbacks |
|
|
14 | |
|
|
15 | # initialise the node so it can send/receive messages |
|
|
16 | initialise_node; |
|
|
17 | |
|
|
18 | # ports are message endpoints |
|
|
19 | |
|
|
20 | # sending messages |
13 | snd $port, type => data...; |
21 | snd $port, type => data...; |
|
|
22 | snd $port, @msg; |
|
|
23 | snd @msg_with_first_element_being_a_port; |
14 | |
24 | |
15 | $SELF # receiving/own port id in rcv callbacks |
25 | # creating/using ports, the simple way |
|
|
26 | my $simple_port = port { my @msg = @_; 0 }; |
16 | |
27 | |
17 | rcv $port, smartmatch => $cb->($port, @msg); |
28 | # creating/using ports, tagged message matching |
18 | |
29 | my $port = port; |
19 | # examples: |
|
|
20 | rcv $port2, ping => sub { snd $_[0], "pong"; 0 }; |
30 | rcv $port, ping => sub { snd $_[0], "pong"; 0 }; |
21 | rcv $port1, pong => sub { warn "pong received\n" }; |
31 | rcv $port, pong => sub { warn "pong received\n"; 0 }; |
22 | snd $port2, ping => $port1; |
|
|
23 | |
32 | |
24 | # more, smarter, matches (_any_ is exported by this module) |
33 | # create a port on another node |
25 | rcv $port, [child_died => $pid] => sub { ... |
34 | my $port = spawn $node, $initfunc, @initdata; |
26 | rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3 |
35 | |
|
|
36 | # monitoring |
|
|
37 | mon $port, $cb->(@msg) # callback is invoked on death |
|
|
38 | mon $port, $otherport # kill otherport on abnormal death |
|
|
39 | mon $port, $otherport, @msg # send message on death |
|
|
40 | |
|
|
41 | =head1 CURRENT STATUS |
|
|
42 | |
|
|
43 | bin/aemp - stable. |
|
|
44 | AnyEvent::MP - stable API, should work. |
|
|
45 | AnyEvent::MP::Intro - uptodate, but incomplete. |
|
|
46 | AnyEvent::MP::Kernel - mostly stable. |
|
|
47 | AnyEvent::MP::Global - stable API, protocol not yet final. |
|
|
48 | |
|
|
49 | stay tuned. |
27 | |
50 | |
28 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
29 | |
52 | |
30 | This module (-family) implements a simple message passing framework. |
53 | This module (-family) implements a simple message passing framework. |
31 | |
54 | |
32 | Despite its simplicity, you can securely message other processes running |
55 | Despite its simplicity, you can securely message other processes running |
33 | on the same or other hosts. |
56 | on the same or other hosts, and you can supervise entities remotely. |
34 | |
57 | |
|
|
58 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
|
|
59 | manual page and the examples under F<eg/>. |
|
|
60 | |
35 | At the moment, this module family is severly brokena nd underdocumented, |
61 | At the moment, this module family is a bit underdocumented. |
36 | so do not use. This was uploaded mainly to reserve the CPAN namespace - |
|
|
37 | stay tuned! |
|
|
38 | |
62 | |
39 | =head1 CONCEPTS |
63 | =head1 CONCEPTS |
40 | |
64 | |
41 | =over 4 |
65 | =over 4 |
42 | |
66 | |
43 | =item port |
67 | =item port |
44 | |
68 | |
45 | A port is something you can send messages to with the C<snd> function, and |
69 | A port is something you can send messages to (with the C<snd> function). |
46 | you can register C<rcv> handlers with. All C<rcv> handlers will receive |
|
|
47 | messages they match, messages will not be queued. |
|
|
48 | |
70 | |
|
|
71 | Ports allow you to register C<rcv> handlers that can match all or just |
|
|
72 | some messages. Messages send to ports will not be queued, regardless of |
|
|
73 | anything was listening for them or not. |
|
|
74 | |
49 | =item port id - C<noderef#portname> |
75 | =item port ID - C<nodeid#portname> |
50 | |
76 | |
51 | A port id is always the noderef, a hash-mark (C<#>) as separator, followed |
77 | A port ID is the concatenation of a node ID, a hash-mark (C<#>) as |
52 | by a port name (a printable string of unspecified format). |
78 | separator, and a port name (a printable string of unspecified format). |
53 | |
79 | |
54 | =item node |
80 | =item node |
55 | |
81 | |
56 | A node is a single process containing at least one port - the node |
82 | A node is a single process containing at least one port - the node port, |
57 | port. You can send messages to node ports to let them create new ports, |
83 | which enables nodes to manage each other remotely, and to create new |
58 | among other things. |
84 | ports. |
59 | |
85 | |
60 | Initially, nodes are either private (single-process only) or hidden |
86 | Nodes are either public (have one or more listening ports) or private |
61 | (connected to a master node only). Only when they epxlicitly "become |
87 | (no listening ports). Private nodes cannot talk to other private nodes |
62 | public" can you send them messages from unrelated other nodes. |
88 | currently. |
63 | |
89 | |
64 | =item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> |
90 | =item node ID - C<[a-za-Z0-9_\-.:]+> |
65 | |
91 | |
66 | A noderef is a string that either uniquely identifies a given node (for |
92 | A node ID is a string that uniquely identifies the node within a |
67 | private and hidden nodes), or contains a recipe on how to reach a given |
93 | network. Depending on the configuration used, node IDs can look like a |
68 | node (for public nodes). |
94 | hostname, a hostname and a port, or a random string. AnyEvent::MP itself |
|
|
95 | doesn't interpret node IDs in any way. |
|
|
96 | |
|
|
97 | =item binds - C<ip:port> |
|
|
98 | |
|
|
99 | Nodes can only talk to each other by creating some kind of connection to |
|
|
100 | each other. To do this, nodes should listen on one or more local transport |
|
|
101 | endpoints - binds. Currently, only standard C<ip:port> specifications can |
|
|
102 | be used, which specify TCP ports to listen on. |
|
|
103 | |
|
|
104 | =item seeds - C<host:port> |
|
|
105 | |
|
|
106 | When a node starts, it knows nothing about the network. To teach the node |
|
|
107 | about the network it first has to contact some other node within the |
|
|
108 | network. This node is called a seed. |
|
|
109 | |
|
|
110 | Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes |
|
|
111 | are expected to be long-running, and at least one of those should always |
|
|
112 | be available. When nodes run out of connections (e.g. due to a network |
|
|
113 | error), they try to re-establish connections to some seednodes again to |
|
|
114 | join the network. |
|
|
115 | |
|
|
116 | Apart from being sued for seeding, seednodes are not special in any way - |
|
|
117 | every public node can be a seednode. |
69 | |
118 | |
70 | =back |
119 | =back |
71 | |
120 | |
72 | =head1 VARIABLES/FUNCTIONS |
121 | =head1 VARIABLES/FUNCTIONS |
73 | |
122 | |
… | |
… | |
75 | |
124 | |
76 | =cut |
125 | =cut |
77 | |
126 | |
78 | package AnyEvent::MP; |
127 | package AnyEvent::MP; |
79 | |
128 | |
80 | use AnyEvent::MP::Base; |
129 | use AnyEvent::MP::Kernel; |
81 | |
130 | |
82 | use common::sense; |
131 | use common::sense; |
83 | |
132 | |
84 | use Carp (); |
133 | use Carp (); |
85 | |
134 | |
86 | use AE (); |
135 | use AE (); |
87 | |
136 | |
88 | use base "Exporter"; |
137 | use base "Exporter"; |
89 | |
138 | |
90 | our $VERSION = '0.02'; |
139 | our $VERSION = $AnyEvent::MP::Kernel::VERSION; |
|
|
140 | |
91 | our @EXPORT = qw( |
141 | our @EXPORT = qw( |
92 | NODE $NODE *SELF node_of _any_ |
142 | NODE $NODE *SELF node_of after |
93 | become_slave become_public |
143 | initialise_node |
94 | snd rcv mon kil reg psub |
144 | snd rcv mon mon_guard kil reg psub spawn |
95 | port |
145 | port |
96 | ); |
146 | ); |
97 | |
147 | |
98 | our $SELF; |
148 | our $SELF; |
99 | |
149 | |
… | |
… | |
103 | kil $SELF, die => $msg; |
153 | kil $SELF, die => $msg; |
104 | } |
154 | } |
105 | |
155 | |
106 | =item $thisnode = NODE / $NODE |
156 | =item $thisnode = NODE / $NODE |
107 | |
157 | |
108 | The C<NODE> function returns, and the C<$NODE> variable contains |
158 | The C<NODE> function returns, and the C<$NODE> variable contains, the node |
109 | the noderef of the local node. The value is initialised by a call |
159 | ID of the node running in the current process. This value is initialised by |
110 | to C<become_public> or C<become_slave>, after which all local port |
160 | a call to C<initialise_node>. |
111 | identifiers become invalid. |
|
|
112 | |
161 | |
113 | =item $noderef = node_of $portid |
162 | =item $nodeid = node_of $port |
114 | |
163 | |
115 | Extracts and returns the noderef from a portid or a noderef. |
164 | Extracts and returns the node ID from a port ID or a node ID. |
|
|
165 | |
|
|
166 | =item initialise_node $profile_name, key => value... |
|
|
167 | |
|
|
168 | Before a node can talk to other nodes on the network (i.e. enter |
|
|
169 | "distributed mode") it has to initialise itself - the minimum a node needs |
|
|
170 | to know is its own name, and optionally it should know the addresses of |
|
|
171 | some other nodes in the network to discover other nodes. |
|
|
172 | |
|
|
173 | This function initialises a node - it must be called exactly once (or |
|
|
174 | never) before calling other AnyEvent::MP functions. |
|
|
175 | |
|
|
176 | The first argument is a profile name. If it is C<undef> or missing, then |
|
|
177 | the current nodename will be used instead (i.e. F<uname -n>). |
|
|
178 | |
|
|
179 | The function first looks up the profile in the aemp configuration (see the |
|
|
180 | L<aemp> commandline utility). the profile is calculated as follows: |
|
|
181 | |
|
|
182 | First, all remaining key => value pairs (all of which are conviniently |
|
|
183 | undocumented at the moment) will be used. Then they will be overwritten by |
|
|
184 | any values specified in the global default configuration (see the F<aemp> |
|
|
185 | utility), then the chain of profiles selected, if any. That means that |
|
|
186 | the values specified in the profile have highest priority and the values |
|
|
187 | specified via C<initialise_node> have lowest priority. |
|
|
188 | |
|
|
189 | If the profile specifies a node ID, then this will become the node ID of |
|
|
190 | this process. If not, then the profile name will be used as node ID. The |
|
|
191 | special node ID of C<anon/> will be replaced by a random node ID. |
|
|
192 | |
|
|
193 | The next step is to look up the binds in the profile, followed by binding |
|
|
194 | aemp protocol listeners on all binds specified (it is possible and valid |
|
|
195 | to have no binds, meaning that the node cannot be contacted form the |
|
|
196 | outside. This means the node cannot talk to other nodes that also have no |
|
|
197 | binds, but it can still talk to all "normal" nodes). |
|
|
198 | |
|
|
199 | If the profile does not specify a binds list, then a default of C<*> is |
|
|
200 | used. |
|
|
201 | |
|
|
202 | Lastly, the seeds list from the profile is passed to the |
|
|
203 | L<AnyEvent::MP::Global> module, which will then use it to keep |
|
|
204 | connectivity with at least on of those seed nodes at any point in time. |
|
|
205 | |
|
|
206 | Example: become a distributed node listening on the guessed noderef, or |
|
|
207 | the one specified via C<aemp> for the current node. This should be the |
|
|
208 | most common form of invocation for "daemon"-type nodes. |
|
|
209 | |
|
|
210 | initialise_node; |
|
|
211 | |
|
|
212 | Example: become an anonymous node. This form is often used for commandline |
|
|
213 | clients. |
|
|
214 | |
|
|
215 | initialise_node "anon/"; |
|
|
216 | |
|
|
217 | Example: become a distributed node. If there is no profile of the given |
|
|
218 | name, or no binds list was specified, resolve C<localhost:4044> and bind |
|
|
219 | on the resulting addresses. |
|
|
220 | |
|
|
221 | initialise_node "localhost:4044"; |
116 | |
222 | |
117 | =item $SELF |
223 | =item $SELF |
118 | |
224 | |
119 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
225 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
120 | blocks. |
226 | blocks. |
121 | |
227 | |
122 | =item SELF, %SELF, @SELF... |
228 | =item *SELF, SELF, %SELF, @SELF... |
123 | |
229 | |
124 | Due to some quirks in how perl exports variables, it is impossible to |
230 | Due to some quirks in how perl exports variables, it is impossible to |
125 | just export C<$SELF>, all the symbols called C<SELF> are exported by this |
231 | just export C<$SELF>, all the symbols named C<SELF> are exported by this |
126 | module, but only C<$SELF> is currently used. |
232 | module, but only C<$SELF> is currently used. |
127 | |
233 | |
128 | =item snd $portid, type => @data |
234 | =item snd $port, type => @data |
129 | |
235 | |
130 | =item snd $portid, @msg |
236 | =item snd $port, @msg |
131 | |
237 | |
132 | Send the given message to the given port ID, which can identify either |
238 | Send the given message to the given port, which can identify either a |
133 | a local or a remote port, and can be either a string or soemthignt hat |
239 | local or a remote port, and must be a port ID. |
134 | stringifies a sa port ID (such as a port object :). |
|
|
135 | |
240 | |
136 | While the message can be about anything, it is highly recommended to use a |
241 | While the message can be almost anything, it is highly recommended to |
137 | string as first element (a portid, or some word that indicates a request |
242 | use a string as first element (a port ID, or some word that indicates a |
138 | type etc.). |
243 | request type etc.) and to consist if only simple perl values (scalars, |
|
|
244 | arrays, hashes) - if you think you need to pass an object, think again. |
139 | |
245 | |
140 | The message data effectively becomes read-only after a call to this |
246 | The message data logically becomes read-only after a call to this |
141 | function: modifying any argument is not allowed and can cause many |
247 | function: modifying any argument (or values referenced by them) is |
142 | problems. |
248 | forbidden, as there can be considerable time between the call to C<snd> |
|
|
249 | and the time the message is actually being serialised - in fact, it might |
|
|
250 | never be copied as within the same process it is simply handed to the |
|
|
251 | receiving port. |
143 | |
252 | |
144 | The type of data you can transfer depends on the transport protocol: when |
253 | The type of data you can transfer depends on the transport protocol: when |
145 | JSON is used, then only strings, numbers and arrays and hashes consisting |
254 | JSON is used, then only strings, numbers and arrays and hashes consisting |
146 | of those are allowed (no objects). When Storable is used, then anything |
255 | of those are allowed (no objects). When Storable is used, then anything |
147 | that Storable can serialise and deserialise is allowed, and for the local |
256 | that Storable can serialise and deserialise is allowed, and for the local |
148 | node, anything can be passed. |
257 | node, anything can be passed. Best rely only on the common denominator of |
|
|
258 | these. |
149 | |
259 | |
150 | =item kil $portid[, @reason] |
260 | =item $local_port = port |
151 | |
261 | |
152 | Kill the specified port with the given C<@reason>. |
262 | Create a new local port object and returns its port ID. Initially it has |
|
|
263 | no callbacks set and will throw an error when it receives messages. |
153 | |
264 | |
154 | If no C<@reason> is specified, then the port is killed "normally" (linked |
265 | =item $local_port = port { my @msg = @_ } |
155 | ports will not be kileld, or even notified). |
|
|
156 | |
266 | |
157 | Otherwise, linked ports get killed with the same reason (second form of |
267 | Creates a new local port, and returns its ID. Semantically the same as |
158 | C<mon>, see below). |
268 | creating a port and calling C<rcv $port, $callback> on it. |
159 | |
269 | |
160 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
270 | The block will be called for every message received on the port, with the |
161 | will be reported as reason C<< die => $@ >>. |
271 | global variable C<$SELF> set to the port ID. Runtime errors will cause the |
|
|
272 | port to be C<kil>ed. The message will be passed as-is, no extra argument |
|
|
273 | (i.e. no port ID) will be passed to the callback. |
162 | |
274 | |
163 | Transport/communication errors are reported as C<< transport_error => |
275 | If you want to stop/destroy the port, simply C<kil> it: |
164 | $message >>. |
|
|
165 | |
276 | |
166 | =item $guard = mon $portid, $cb->(@reason) |
277 | my $port = port { |
|
|
278 | my @msg = @_; |
|
|
279 | ... |
|
|
280 | kil $SELF; |
|
|
281 | }; |
167 | |
282 | |
168 | =item $guard = mon $portid, $otherport |
283 | =cut |
169 | |
284 | |
170 | =item $guard = mon $portid, $otherport, @msg |
285 | sub rcv($@); |
171 | |
286 | |
|
|
287 | sub _kilme { |
|
|
288 | die "received message on port without callback"; |
|
|
289 | } |
|
|
290 | |
|
|
291 | sub port(;&) { |
|
|
292 | my $id = "$UNIQ." . $ID++; |
|
|
293 | my $port = "$NODE#$id"; |
|
|
294 | |
|
|
295 | rcv $port, shift || \&_kilme; |
|
|
296 | |
|
|
297 | $port |
|
|
298 | } |
|
|
299 | |
|
|
300 | =item rcv $local_port, $callback->(@msg) |
|
|
301 | |
|
|
302 | Replaces the default callback on the specified port. There is no way to |
|
|
303 | remove the default callback: use C<sub { }> to disable it, or better |
|
|
304 | C<kil> the port when it is no longer needed. |
|
|
305 | |
|
|
306 | The global C<$SELF> (exported by this module) contains C<$port> while |
|
|
307 | executing the callback. Runtime errors during callback execution will |
|
|
308 | result in the port being C<kil>ed. |
|
|
309 | |
|
|
310 | The default callback received all messages not matched by a more specific |
|
|
311 | C<tag> match. |
|
|
312 | |
|
|
313 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
|
|
314 | |
|
|
315 | Register (or replace) callbacks to be called on messages starting with the |
|
|
316 | given tag on the given port (and return the port), or unregister it (when |
|
|
317 | C<$callback> is C<$undef> or missing). There can only be one callback |
|
|
318 | registered for each tag. |
|
|
319 | |
|
|
320 | The original message will be passed to the callback, after the first |
|
|
321 | element (the tag) has been removed. The callback will use the same |
|
|
322 | environment as the default callback (see above). |
|
|
323 | |
|
|
324 | Example: create a port and bind receivers on it in one go. |
|
|
325 | |
|
|
326 | my $port = rcv port, |
|
|
327 | msg1 => sub { ... }, |
|
|
328 | msg2 => sub { ... }, |
|
|
329 | ; |
|
|
330 | |
|
|
331 | Example: create a port, bind receivers and send it in a message elsewhere |
|
|
332 | in one go: |
|
|
333 | |
|
|
334 | snd $otherport, reply => |
|
|
335 | rcv port, |
|
|
336 | msg1 => sub { ... }, |
|
|
337 | ... |
|
|
338 | ; |
|
|
339 | |
|
|
340 | Example: temporarily register a rcv callback for a tag matching some port |
|
|
341 | (e.g. for a rpc reply) and unregister it after a message was received. |
|
|
342 | |
|
|
343 | rcv $port, $otherport => sub { |
|
|
344 | my @reply = @_; |
|
|
345 | |
|
|
346 | rcv $SELF, $otherport; |
|
|
347 | }; |
|
|
348 | |
|
|
349 | =cut |
|
|
350 | |
|
|
351 | sub rcv($@) { |
|
|
352 | my $port = shift; |
|
|
353 | my ($noderef, $portid) = split /#/, $port, 2; |
|
|
354 | |
|
|
355 | $NODE{$noderef} == $NODE{""} |
|
|
356 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
|
|
357 | |
|
|
358 | while (@_) { |
|
|
359 | if (ref $_[0]) { |
|
|
360 | if (my $self = $PORT_DATA{$portid}) { |
|
|
361 | "AnyEvent::MP::Port" eq ref $self |
|
|
362 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
|
|
363 | |
|
|
364 | $self->[2] = shift; |
|
|
365 | } else { |
|
|
366 | my $cb = shift; |
|
|
367 | $PORT{$portid} = sub { |
|
|
368 | local $SELF = $port; |
|
|
369 | eval { &$cb }; _self_die if $@; |
|
|
370 | }; |
|
|
371 | } |
|
|
372 | } elsif (defined $_[0]) { |
|
|
373 | my $self = $PORT_DATA{$portid} ||= do { |
|
|
374 | my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
|
|
375 | |
|
|
376 | $PORT{$portid} = sub { |
|
|
377 | local $SELF = $port; |
|
|
378 | |
|
|
379 | if (my $cb = $self->[1]{$_[0]}) { |
|
|
380 | shift; |
|
|
381 | eval { &$cb }; _self_die if $@; |
|
|
382 | } else { |
|
|
383 | &{ $self->[0] }; |
|
|
384 | } |
|
|
385 | }; |
|
|
386 | |
|
|
387 | $self |
|
|
388 | }; |
|
|
389 | |
|
|
390 | "AnyEvent::MP::Port" eq ref $self |
|
|
391 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
|
|
392 | |
|
|
393 | my ($tag, $cb) = splice @_, 0, 2; |
|
|
394 | |
|
|
395 | if (defined $cb) { |
|
|
396 | $self->[1]{$tag} = $cb; |
|
|
397 | } else { |
|
|
398 | delete $self->[1]{$tag}; |
|
|
399 | } |
|
|
400 | } |
|
|
401 | } |
|
|
402 | |
|
|
403 | $port |
|
|
404 | } |
|
|
405 | |
|
|
406 | =item $closure = psub { BLOCK } |
|
|
407 | |
|
|
408 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
|
|
409 | closure is executed, sets up the environment in the same way as in C<rcv> |
|
|
410 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
|
|
411 | |
|
|
412 | This is useful when you register callbacks from C<rcv> callbacks: |
|
|
413 | |
|
|
414 | rcv delayed_reply => sub { |
|
|
415 | my ($delay, @reply) = @_; |
|
|
416 | my $timer = AE::timer $delay, 0, psub { |
|
|
417 | snd @reply, $SELF; |
|
|
418 | }; |
|
|
419 | }; |
|
|
420 | |
|
|
421 | =cut |
|
|
422 | |
|
|
423 | sub psub(&) { |
|
|
424 | my $cb = shift; |
|
|
425 | |
|
|
426 | my $port = $SELF |
|
|
427 | or Carp::croak "psub can only be called from within rcv or psub callbacks, not"; |
|
|
428 | |
|
|
429 | sub { |
|
|
430 | local $SELF = $port; |
|
|
431 | |
|
|
432 | if (wantarray) { |
|
|
433 | my @res = eval { &$cb }; |
|
|
434 | _self_die if $@; |
|
|
435 | @res |
|
|
436 | } else { |
|
|
437 | my $res = eval { &$cb }; |
|
|
438 | _self_die if $@; |
|
|
439 | $res |
|
|
440 | } |
|
|
441 | } |
|
|
442 | } |
|
|
443 | |
|
|
444 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
|
|
445 | |
|
|
446 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
447 | |
|
|
448 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
449 | |
|
|
450 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
|
|
451 | |
172 | Monitor the given port and do something when the port is killed. |
452 | Monitor the given port and do something when the port is killed or |
|
|
453 | messages to it were lost, and optionally return a guard that can be used |
|
|
454 | to stop monitoring again. |
173 | |
455 | |
|
|
456 | C<mon> effectively guarantees that, in the absence of hardware failures, |
|
|
457 | after starting the monitor, either all messages sent to the port will |
|
|
458 | arrive, or the monitoring action will be invoked after possible message |
|
|
459 | loss has been detected. No messages will be lost "in between" (after |
|
|
460 | the first lost message no further messages will be received by the |
|
|
461 | port). After the monitoring action was invoked, further messages might get |
|
|
462 | delivered again. |
|
|
463 | |
|
|
464 | Note that monitoring-actions are one-shot: once messages are lost (and a |
|
|
465 | monitoring alert was raised), they are removed and will not trigger again. |
|
|
466 | |
174 | In the first form, the callback is simply called with any number |
467 | In the first form (callback), the callback is simply called with any |
175 | of C<@reason> elements (no @reason means that the port was deleted |
468 | number of C<@reason> elements (no @reason means that the port was deleted |
176 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
469 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
177 | C<eval> if unsure. |
470 | C<eval> if unsure. |
178 | |
471 | |
179 | In the second form, the other port will be C<kil>'ed with C<@reason>, iff |
472 | In the second form (another port given), the other port (C<$rcvport>) |
180 | a @reason was specified, i.e. on "normal" kils nothing happens, while |
473 | will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on |
181 | under all other conditions, the other port is killed with the same reason. |
474 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
475 | port is killed with the same reason. |
182 | |
476 | |
|
|
477 | The third form (kill self) is the same as the second form, except that |
|
|
478 | C<$rvport> defaults to C<$SELF>. |
|
|
479 | |
183 | In the last form, a message of the form C<@msg, @reason> will be C<snd>. |
480 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
481 | C<snd>. |
|
|
482 | |
|
|
483 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
484 | a local port (or callback). The reason is that kill messages might get |
|
|
485 | lost, just like any other message. Another less obvious reason is that |
|
|
486 | even monitoring requests can get lost (for exmaple, when the connection |
|
|
487 | to the other node goes down permanently). When monitoring a port locally |
|
|
488 | these problems do not exist. |
184 | |
489 | |
185 | Example: call a given callback when C<$port> is killed. |
490 | Example: call a given callback when C<$port> is killed. |
186 | |
491 | |
187 | mon $port, sub { warn "port died because of <@_>\n" }; |
492 | mon $port, sub { warn "port died because of <@_>\n" }; |
188 | |
493 | |
189 | Example: kill ourselves when C<$port> is killed abnormally. |
494 | Example: kill ourselves when C<$port> is killed abnormally. |
190 | |
495 | |
191 | mon $port, $self; |
496 | mon $port; |
192 | |
497 | |
193 | Example: send us a restart message another C<$port> is killed. |
498 | Example: send us a restart message when another C<$port> is killed. |
194 | |
499 | |
195 | mon $port, $self => "restart"; |
500 | mon $port, $self => "restart"; |
196 | |
501 | |
197 | =cut |
502 | =cut |
198 | |
503 | |
199 | sub mon { |
504 | sub mon { |
200 | my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift); |
505 | my ($noderef, $port) = split /#/, shift, 2; |
201 | |
506 | |
202 | my $node = $NODE{$noderef} || add_node $noderef; |
507 | my $node = $NODE{$noderef} || add_node $noderef; |
203 | |
508 | |
204 | #TODO: ports must not be references |
509 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
205 | if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) { |
510 | |
|
|
511 | unless (ref $cb) { |
206 | if (@_) { |
512 | if (@_) { |
207 | # send a kill info message |
513 | # send a kill info message |
208 | my (@msg) = ($cb, @_); |
514 | my (@msg) = ($cb, @_); |
209 | $cb = sub { snd @msg, @_ }; |
515 | $cb = sub { snd @msg, @_ }; |
210 | } else { |
516 | } else { |
… | |
… | |
226 | is killed, the references will be freed. |
532 | is killed, the references will be freed. |
227 | |
533 | |
228 | Optionally returns a guard that will stop the monitoring. |
534 | Optionally returns a guard that will stop the monitoring. |
229 | |
535 | |
230 | This function is useful when you create e.g. timers or other watchers and |
536 | This function is useful when you create e.g. timers or other watchers and |
231 | want to free them when the port gets killed: |
537 | want to free them when the port gets killed (note the use of C<psub>): |
232 | |
538 | |
233 | $port->rcv (start => sub { |
539 | $port->rcv (start => sub { |
234 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { |
540 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub { |
235 | undef $timer if 0.9 < rand; |
541 | undef $timer if 0.9 < rand; |
236 | }); |
542 | }); |
237 | }); |
543 | }); |
238 | |
544 | |
239 | =cut |
545 | =cut |
240 | |
546 | |
241 | sub mon_guard { |
547 | sub mon_guard { |
242 | my ($port, @refs) = @_; |
548 | my ($port, @refs) = @_; |
243 | |
549 | |
|
|
550 | #TODO: mon-less form? |
|
|
551 | |
244 | mon $port, sub { 0 && @refs } |
552 | mon $port, sub { 0 && @refs } |
245 | } |
553 | } |
246 | |
554 | |
247 | =item $local_port = port |
555 | =item kil $port[, @reason] |
248 | |
556 | |
249 | Create a new local port object that supports message matching. |
557 | Kill the specified port with the given C<@reason>. |
250 | |
558 | |
251 | =item $portid = port { my @msg = @_; $finished } |
559 | If no C<@reason> is specified, then the port is killed "normally" (ports |
|
|
560 | monitoring other ports will not necessarily die because a port dies |
|
|
561 | "normally"). |
252 | |
562 | |
253 | Creates a "mini port", that is, a very lightweight port without any |
563 | Otherwise, linked ports get killed with the same reason (second form of |
254 | pattern matching behind it, and returns its ID. |
564 | C<mon>, see above). |
255 | |
565 | |
256 | The block will be called for every message received on the port. When the |
566 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
257 | callback returns a true value its job is considered "done" and the port |
567 | will be reported as reason C<< die => $@ >>. |
258 | will be destroyed. Otherwise it will stay alive. |
|
|
259 | |
568 | |
260 | The message will be passed as-is, no extra argument (i.e. no port id) will |
569 | Transport/communication errors are reported as C<< transport_error => |
261 | be passed to the callback. |
570 | $message >>. |
262 | |
571 | |
263 | If you need the local port id in the callback, this works nicely: |
|
|
264 | |
|
|
265 | my $port; $port = miniport { |
|
|
266 | snd $otherport, reply => $port; |
|
|
267 | }; |
|
|
268 | |
|
|
269 | =cut |
572 | =cut |
270 | |
573 | |
271 | sub port(;&) { |
574 | =item $port = spawn $node, $initfunc[, @initdata] |
272 | my $id = "$UNIQ." . $ID++; |
|
|
273 | my $port = "$NODE#$id"; |
|
|
274 | |
575 | |
275 | if (@_) { |
576 | Creates a port on the node C<$node> (which can also be a port ID, in which |
276 | my $cb = shift; |
577 | case it's the node where that port resides). |
277 | $PORT{$id} = sub { |
578 | |
278 | local $SELF = $port; |
579 | The port ID of the newly created port is returned immediately, and it is |
279 | eval { |
580 | possible to immediately start sending messages or to monitor the port. |
280 | &$cb |
581 | |
281 | and kil $id; |
582 | After the port has been created, the init function is called on the remote |
|
|
583 | node, in the same context as a C<rcv> callback. This function must be a |
|
|
584 | fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To |
|
|
585 | specify a function in the main program, use C<::name>. |
|
|
586 | |
|
|
587 | If the function doesn't exist, then the node tries to C<require> |
|
|
588 | the package, then the package above the package and so on (e.g. |
|
|
589 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
|
|
590 | exists or it runs out of package names. |
|
|
591 | |
|
|
592 | The init function is then called with the newly-created port as context |
|
|
593 | object (C<$SELF>) and the C<@initdata> values as arguments. |
|
|
594 | |
|
|
595 | A common idiom is to pass a local port, immediately monitor the spawned |
|
|
596 | port, and in the remote init function, immediately monitor the passed |
|
|
597 | local port. This two-way monitoring ensures that both ports get cleaned up |
|
|
598 | when there is a problem. |
|
|
599 | |
|
|
600 | Example: spawn a chat server port on C<$othernode>. |
|
|
601 | |
|
|
602 | # this node, executed from within a port context: |
|
|
603 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
|
|
604 | mon $server; |
|
|
605 | |
|
|
606 | # init function on C<$othernode> |
|
|
607 | sub connect { |
|
|
608 | my ($srcport) = @_; |
|
|
609 | |
|
|
610 | mon $srcport; |
|
|
611 | |
|
|
612 | rcv $SELF, sub { |
282 | }; |
613 | ... |
283 | _self_die if $@; |
|
|
284 | }; |
|
|
285 | } else { |
|
|
286 | my $self = bless { |
|
|
287 | id => "$NODE#$id", |
|
|
288 | }, "AnyEvent::MP::Port"; |
|
|
289 | |
|
|
290 | $PORT_DATA{$id} = $self; |
|
|
291 | $PORT{$id} = sub { |
|
|
292 | local $SELF = $port; |
|
|
293 | |
|
|
294 | eval { |
|
|
295 | for (@{ $self->{rc0}{$_[0]} }) { |
|
|
296 | $_ && &{$_->[0]} |
|
|
297 | && undef $_; |
|
|
298 | } |
|
|
299 | |
|
|
300 | for (@{ $self->{rcv}{$_[0]} }) { |
|
|
301 | $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1] |
|
|
302 | && &{$_->[0]} |
|
|
303 | && undef $_; |
|
|
304 | } |
|
|
305 | |
|
|
306 | for (@{ $self->{any} }) { |
|
|
307 | $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1] |
|
|
308 | && &{$_->[0]} |
|
|
309 | && undef $_; |
|
|
310 | } |
|
|
311 | }; |
|
|
312 | _self_die if $@; |
|
|
313 | }; |
614 | }; |
314 | } |
615 | } |
315 | |
616 | |
316 | $port |
|
|
317 | } |
|
|
318 | |
|
|
319 | =item reg $portid, $name |
|
|
320 | |
|
|
321 | Registers the given port under the name C<$name>. If the name already |
|
|
322 | exists it is replaced. |
|
|
323 | |
|
|
324 | A port can only be registered under one well known name. |
|
|
325 | |
|
|
326 | A port automatically becomes unregistered when it is killed. |
|
|
327 | |
|
|
328 | =cut |
617 | =cut |
329 | |
618 | |
330 | sub reg(@) { |
619 | sub _spawn { |
331 | my ($portid, $name) = @_; |
620 | my $port = shift; |
|
|
621 | my $init = shift; |
332 | |
622 | |
333 | $REG{$name} = $portid; |
623 | local $SELF = "$NODE#$port"; |
334 | } |
624 | eval { |
335 | |
625 | &{ load_func $init } |
336 | =item rcv $portid, tagstring => $callback->(@msg), ... |
|
|
337 | |
|
|
338 | =item rcv $portid, $smartmatch => $callback->(@msg), ... |
|
|
339 | |
|
|
340 | =item rcv $portid, [$smartmatch...] => $callback->(@msg), ... |
|
|
341 | |
|
|
342 | Register callbacks to be called on matching messages on the given port. |
|
|
343 | |
|
|
344 | The callback has to return a true value when its work is done, after |
|
|
345 | which is will be removed, or a false value in which case it will stay |
|
|
346 | registered. |
|
|
347 | |
|
|
348 | The global C<$SELF> (exported by this module) contains C<$portid> while |
|
|
349 | executing the callback. |
|
|
350 | |
|
|
351 | Runtime errors wdurign callback execution will result in the port being |
|
|
352 | C<kil>ed. |
|
|
353 | |
|
|
354 | If the match is an array reference, then it will be matched against the |
|
|
355 | first elements of the message, otherwise only the first element is being |
|
|
356 | matched. |
|
|
357 | |
|
|
358 | Any element in the match that is specified as C<_any_> (a function |
|
|
359 | exported by this module) matches any single element of the message. |
|
|
360 | |
|
|
361 | While not required, it is highly recommended that the first matching |
|
|
362 | element is a string identifying the message. The one-string-only match is |
|
|
363 | also the most efficient match (by far). |
|
|
364 | |
|
|
365 | =cut |
|
|
366 | |
|
|
367 | sub rcv($@) { |
|
|
368 | my ($noderef, $port) = split /#/, shift, 2; |
|
|
369 | |
|
|
370 | ($NODE{$noderef} || add_node $noderef) == $NODE{""} |
|
|
371 | or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught"; |
|
|
372 | |
|
|
373 | my $self = $PORT_DATA{$port} |
|
|
374 | or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught"; |
|
|
375 | |
|
|
376 | "AnyEvent::MP::Port" eq ref $self |
|
|
377 | or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught"; |
|
|
378 | |
|
|
379 | while (@_) { |
|
|
380 | my ($match, $cb) = splice @_, 0, 2; |
|
|
381 | |
|
|
382 | if (!ref $match) { |
|
|
383 | push @{ $self->{rc0}{$match} }, [$cb]; |
|
|
384 | } elsif (("ARRAY" eq ref $match && !ref $match->[0])) { |
|
|
385 | my ($type, @match) = @$match; |
|
|
386 | @match |
|
|
387 | ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match] |
|
|
388 | : push @{ $self->{rc0}{$match->[0]} }, [$cb]; |
|
|
389 | } else { |
|
|
390 | push @{ $self->{any} }, [$cb, $match]; |
|
|
391 | } |
|
|
392 | } |
|
|
393 | } |
|
|
394 | |
|
|
395 | =item $closure = psub { BLOCK } |
|
|
396 | |
|
|
397 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
|
|
398 | closure is executed, sets up the environment in the same way as in C<rcv> |
|
|
399 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
|
|
400 | |
|
|
401 | This is useful when you register callbacks from C<rcv> callbacks: |
|
|
402 | |
|
|
403 | rcv delayed_reply => sub { |
|
|
404 | my ($delay, @reply) = @_; |
|
|
405 | my $timer = AE::timer $delay, 0, psub { |
|
|
406 | snd @reply, $SELF; |
|
|
407 | }; |
|
|
408 | }; |
626 | }; |
409 | |
|
|
410 | =cut |
|
|
411 | |
|
|
412 | sub psub(&) { |
|
|
413 | my $cb = shift; |
|
|
414 | |
|
|
415 | my $port = $SELF |
|
|
416 | or Carp::croak "psub can only be called from within rcv or psub callbacks, not"; |
|
|
417 | |
|
|
418 | sub { |
|
|
419 | local $SELF = $port; |
|
|
420 | |
|
|
421 | if (wantarray) { |
|
|
422 | my @res = eval { &$cb }; |
|
|
423 | _self_die if $@; |
627 | _self_die if $@; |
424 | @res |
628 | } |
425 | } else { |
629 | |
426 | my $res = eval { &$cb }; |
630 | sub spawn(@) { |
427 | _self_die if $@; |
631 | my ($noderef, undef) = split /#/, shift, 2; |
428 | $res |
632 | |
429 | } |
633 | my $id = "$RUNIQ." . $ID++; |
|
|
634 | |
|
|
635 | $_[0] =~ /::/ |
|
|
636 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
|
|
637 | |
|
|
638 | snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_; |
|
|
639 | |
|
|
640 | "$noderef#$id" |
|
|
641 | } |
|
|
642 | |
|
|
643 | =item after $timeout, @msg |
|
|
644 | |
|
|
645 | =item after $timeout, $callback |
|
|
646 | |
|
|
647 | Either sends the given message, or call the given callback, after the |
|
|
648 | specified number of seconds. |
|
|
649 | |
|
|
650 | This is simply a utility function that comes in handy at times - the |
|
|
651 | AnyEvent::MP author is not convinced of the wisdom of having it, though, |
|
|
652 | so it may go away in the future. |
|
|
653 | |
|
|
654 | =cut |
|
|
655 | |
|
|
656 | sub after($@) { |
|
|
657 | my ($timeout, @action) = @_; |
|
|
658 | |
|
|
659 | my $t; $t = AE::timer $timeout, 0, sub { |
|
|
660 | undef $t; |
|
|
661 | ref $action[0] |
|
|
662 | ? $action[0]() |
|
|
663 | : snd @action; |
430 | } |
664 | }; |
431 | } |
665 | } |
432 | |
666 | |
433 | =back |
667 | =back |
434 | |
668 | |
435 | =head1 FUNCTIONS FOR NODES |
669 | =head1 AnyEvent::MP vs. Distributed Erlang |
|
|
670 | |
|
|
671 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
|
|
672 | == aemp node, Erlang process == aemp port), so many of the documents and |
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673 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
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674 | sample: |
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675 | |
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676 | http://www.Erlang.se/doc/programming_rules.shtml |
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677 | http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
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678 | http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6 |
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679 | http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
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680 | |
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681 | Despite the similarities, there are also some important differences: |
436 | |
682 | |
437 | =over 4 |
683 | =over 4 |
438 | |
684 | |
439 | =item become_public endpoint... |
685 | =item * Node IDs are arbitrary strings in AEMP. |
440 | |
686 | |
441 | Tells the node to become a public node, i.e. reachable from other nodes. |
687 | Erlang relies on special naming and DNS to work everywhere in the same |
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|
688 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
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689 | configuraiton or DNS), but will otherwise discover other odes itself. |
442 | |
690 | |
443 | If no arguments are given, or the first argument is C<undef>, then |
691 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
444 | AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the |
692 | uses "local ports are like remote ports". |
445 | local nodename resolves to. |
|
|
446 | |
693 | |
447 | Otherwise the first argument must be an array-reference with transport |
694 | The failure modes for local ports are quite different (runtime errors |
448 | endpoints ("ip:port", "hostname:port") or port numbers (in which case the |
695 | only) then for remote ports - when a local port dies, you I<know> it dies, |
449 | local nodename is used as hostname). The endpoints are all resolved and |
696 | when a connection to another node dies, you know nothing about the other |
450 | will become the node reference. |
697 | port. |
451 | |
698 | |
452 | =cut |
699 | Erlang pretends remote ports are as reliable as local ports, even when |
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700 | they are not. |
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701 | |
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702 | AEMP encourages a "treat remote ports differently" philosophy, with local |
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703 | ports being the special case/exception, where transport errors cannot |
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704 | occur. |
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705 | |
|
|
706 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
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707 | |
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708 | Erlang uses processes that selectively receive messages, and therefore |
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709 | needs a queue. AEMP is event based, queuing messages would serve no |
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710 | useful purpose. For the same reason the pattern-matching abilities of |
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711 | AnyEvent::MP are more limited, as there is little need to be able to |
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712 | filter messages without dequeing them. |
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713 | |
|
|
714 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
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715 | |
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|
716 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
|
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717 | |
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|
718 | Sending messages in Erlang is synchronous and blocks the process (and |
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719 | so does not need a queue that can overflow). AEMP sends are immediate, |
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|
720 | connection establishment is handled in the background. |
|
|
721 | |
|
|
722 | =item * Erlang suffers from silent message loss, AEMP does not. |
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|
723 | |
|
|
724 | Erlang makes few guarantees on messages delivery - messages can get lost |
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725 | without any of the processes realising it (i.e. you send messages a, b, |
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726 | and c, and the other side only receives messages a and c). |
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727 | |
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728 | AEMP guarantees correct ordering, and the guarantee that after one message |
|
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729 | is lost, all following ones sent to the same port are lost as well, until |
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730 | monitoring raises an error, so there are no silent "holes" in the message |
|
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731 | sequence. |
|
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732 | |
|
|
733 | =item * Erlang can send messages to the wrong port, AEMP does not. |
|
|
734 | |
|
|
735 | In Erlang it is quite likely that a node that restarts reuses a process ID |
|
|
736 | known to other nodes for a completely different process, causing messages |
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737 | destined for that process to end up in an unrelated process. |
|
|
738 | |
|
|
739 | AEMP never reuses port IDs, so old messages or old port IDs floating |
|
|
740 | around in the network will not be sent to an unrelated port. |
|
|
741 | |
|
|
742 | =item * Erlang uses unprotected connections, AEMP uses secure |
|
|
743 | authentication and can use TLS. |
|
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744 | |
|
|
745 | AEMP can use a proven protocol - TLS - to protect connections and |
|
|
746 | securely authenticate nodes. |
|
|
747 | |
|
|
748 | =item * The AEMP protocol is optimised for both text-based and binary |
|
|
749 | communications. |
|
|
750 | |
|
|
751 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
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|
752 | language independent text-only protocols (good for debugging) and binary, |
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753 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
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754 | used, the protocol is actually completely text-based. |
|
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755 | |
|
|
756 | It has also been carefully designed to be implementable in other languages |
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|
757 | with a minimum of work while gracefully degrading functionality to make the |
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|
758 | protocol simple. |
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|
759 | |
|
|
760 | =item * AEMP has more flexible monitoring options than Erlang. |
|
|
761 | |
|
|
762 | In Erlang, you can chose to receive I<all> exit signals as messages |
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|
763 | or I<none>, there is no in-between, so monitoring single processes is |
|
|
764 | difficult to implement. Monitoring in AEMP is more flexible than in |
|
|
765 | Erlang, as one can choose between automatic kill, exit message or callback |
|
|
766 | on a per-process basis. |
|
|
767 | |
|
|
768 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
|
|
769 | |
|
|
770 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
|
|
771 | same way as linking is (except linking is unreliable in Erlang). |
|
|
772 | |
|
|
773 | In AEMP, you don't "look up" registered port names or send to named ports |
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|
774 | that might or might not be persistent. Instead, you normally spawn a port |
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|
775 | on the remote node. The init function monitors you, and you monitor the |
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776 | remote port. Since both monitors are local to the node, they are much more |
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|
777 | reliable (no need for C<spawn_link>). |
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|
778 | |
|
|
779 | This also saves round-trips and avoids sending messages to the wrong port |
|
|
780 | (hard to do in Erlang). |
453 | |
781 | |
454 | =back |
782 | =back |
455 | |
783 | |
456 | =head1 NODE MESSAGES |
784 | =head1 RATIONALE |
457 | |
|
|
458 | Nodes understand the following messages sent to them. Many of them take |
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|
459 | arguments called C<@reply>, which will simply be used to compose a reply |
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|
460 | message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and |
|
|
461 | the remaining arguments are simply the message data. |
|
|
462 | |
785 | |
463 | =over 4 |
786 | =over 4 |
464 | |
787 | |
465 | =cut |
788 | =item Why strings for port and node IDs, why not objects? |
466 | |
789 | |
467 | =item lookup => $name, @reply |
790 | We considered "objects", but found that the actual number of methods |
|
|
791 | that can be called are quite low. Since port and node IDs travel over |
|
|
792 | the network frequently, the serialising/deserialising would add lots of |
|
|
793 | overhead, as well as having to keep a proxy object everywhere. |
468 | |
794 | |
469 | Replies with the port ID of the specified well-known port, or C<undef>. |
795 | Strings can easily be printed, easily serialised etc. and need no special |
|
|
796 | procedures to be "valid". |
470 | |
797 | |
471 | =item devnull => ... |
798 | And as a result, a miniport consists of a single closure stored in a |
|
|
799 | global hash - it can't become much cheaper. |
472 | |
800 | |
473 | Generic data sink/CPU heat conversion. |
801 | =item Why favour JSON, why not a real serialising format such as Storable? |
474 | |
802 | |
475 | =item relay => $port, @msg |
803 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
|
|
804 | format, but currently there is no way to make a node use Storable by |
|
|
805 | default (although all nodes will accept it). |
476 | |
806 | |
477 | Simply forwards the message to the given port. |
807 | The default framing protocol is JSON because a) JSON::XS is many times |
|
|
808 | faster for small messages and b) most importantly, after years of |
|
|
809 | experience we found that object serialisation is causing more problems |
|
|
810 | than it solves: Just like function calls, objects simply do not travel |
|
|
811 | easily over the network, mostly because they will always be a copy, so you |
|
|
812 | always have to re-think your design. |
478 | |
813 | |
479 | =item eval => $string[ @reply] |
814 | Keeping your messages simple, concentrating on data structures rather than |
480 | |
815 | objects, will keep your messages clean, tidy and efficient. |
481 | Evaluates the given string. If C<@reply> is given, then a message of the |
|
|
482 | form C<@reply, $@, @evalres> is sent. |
|
|
483 | |
|
|
484 | Example: crash another node. |
|
|
485 | |
|
|
486 | snd $othernode, eval => "exit"; |
|
|
487 | |
|
|
488 | =item time => @reply |
|
|
489 | |
|
|
490 | Replies the the current node time to C<@reply>. |
|
|
491 | |
|
|
492 | Example: tell the current node to send the current time to C<$myport> in a |
|
|
493 | C<timereply> message. |
|
|
494 | |
|
|
495 | snd $NODE, time => $myport, timereply => 1, 2; |
|
|
496 | # => snd $myport, timereply => 1, 2, <time> |
|
|
497 | |
816 | |
498 | =back |
817 | =back |
499 | |
818 | |
500 | =head1 SEE ALSO |
819 | =head1 SEE ALSO |
|
|
820 | |
|
|
821 | L<AnyEvent::MP::Intro> - a gentle introduction. |
|
|
822 | |
|
|
823 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
|
|
824 | |
|
|
825 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
|
|
826 | your applications. |
501 | |
827 | |
502 | L<AnyEvent>. |
828 | L<AnyEvent>. |
503 | |
829 | |
504 | =head1 AUTHOR |
830 | =head1 AUTHOR |
505 | |
831 | |