… | |
… | |
8 | |
8 | |
9 | $NODE # contains this node's noderef |
9 | $NODE # contains this node's noderef |
10 | NODE # returns this node's noderef |
10 | NODE # returns this node's noderef |
11 | NODE $port # returns the noderef of the port |
11 | NODE $port # returns the noderef of the port |
12 | |
12 | |
|
|
13 | $SELF # receiving/own port id in rcv callbacks |
|
|
14 | |
|
|
15 | # ports are message endpoints |
|
|
16 | |
|
|
17 | # sending messages |
13 | snd $port, type => data...; |
18 | snd $port, type => data...; |
|
|
19 | snd $port, @msg; |
|
|
20 | snd @msg_with_first_element_being_a_port; |
14 | |
21 | |
15 | $SELF # receiving/own port id in rcv callbacks |
22 | # miniports |
|
|
23 | my $miniport = port { my @msg = @_; 0 }; |
16 | |
24 | |
|
|
25 | # full ports |
|
|
26 | my $port = port; |
17 | rcv $port, smartmatch => $cb->($port, @msg); |
27 | rcv $port, smartmatch => $cb->(@msg); |
18 | |
|
|
19 | # examples: |
|
|
20 | rcv $port2, ping => sub { snd $_[0], "pong"; 0 }; |
28 | rcv $port, ping => sub { snd $_[0], "pong"; 0 }; |
21 | rcv $port1, pong => sub { warn "pong received\n" }; |
29 | rcv $port, pong => sub { warn "pong received\n"; 0 }; |
22 | snd $port2, ping => $port1; |
30 | |
|
|
31 | # remote ports |
|
|
32 | my $port = spawn $node, $initfunc, @initdata; |
23 | |
33 | |
24 | # more, smarter, matches (_any_ is exported by this module) |
34 | # more, smarter, matches (_any_ is exported by this module) |
25 | rcv $port, [child_died => $pid] => sub { ... |
35 | rcv $port, [child_died => $pid] => sub { ... |
26 | rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3 |
36 | rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3 |
27 | |
37 | |
|
|
38 | # monitoring |
|
|
39 | mon $port, $cb->(@msg) # callback is invoked on death |
|
|
40 | mon $port, $otherport # kill otherport on abnormal death |
|
|
41 | mon $port, $otherport, @msg # send message on death |
|
|
42 | |
|
|
43 | =head1 CURRENT STATUS |
|
|
44 | |
|
|
45 | AnyEvent::MP - stable API, should work |
|
|
46 | AnyEvent::MP::Intro - outdated |
|
|
47 | AnyEvent::MP::Kernel - WIP |
|
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48 | AnyEvent::MP::Transport - mostly stable |
|
|
49 | |
|
|
50 | stay tuned. |
|
|
51 | |
28 | =head1 DESCRIPTION |
52 | =head1 DESCRIPTION |
29 | |
53 | |
30 | This module (-family) implements a simple message passing framework. |
54 | This module (-family) implements a simple message passing framework. |
31 | |
55 | |
32 | Despite its simplicity, you can securely message other processes running |
56 | Despite its simplicity, you can securely message other processes running |
… | |
… | |
35 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
59 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
36 | manual page. |
60 | manual page. |
37 | |
61 | |
38 | At the moment, this module family is severly broken and underdocumented, |
62 | At the moment, this module family is severly broken and underdocumented, |
39 | so do not use. This was uploaded mainly to reserve the CPAN namespace - |
63 | so do not use. This was uploaded mainly to reserve the CPAN namespace - |
40 | stay tuned! The basic API should be finished, however. |
64 | stay tuned! |
41 | |
65 | |
42 | =head1 CONCEPTS |
66 | =head1 CONCEPTS |
43 | |
67 | |
44 | =over 4 |
68 | =over 4 |
45 | |
69 | |
46 | =item port |
70 | =item port |
47 | |
71 | |
48 | A port is something you can send messages to with the C<snd> function, and |
72 | A port is something you can send messages to (with the C<snd> function). |
49 | you can register C<rcv> handlers with. All C<rcv> handlers will receive |
73 | |
50 | messages they match, messages will not be queued. |
74 | Some ports allow you to register C<rcv> handlers that can match specific |
|
|
75 | messages. All C<rcv> handlers will receive messages they match, messages |
|
|
76 | will not be queued. |
51 | |
77 | |
52 | =item port id - C<noderef#portname> |
78 | =item port id - C<noderef#portname> |
53 | |
79 | |
54 | A port id is always the noderef, a hash-mark (C<#>) as separator, followed |
80 | A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as |
55 | by a port name (a printable string of unspecified format). |
81 | separator, and a port name (a printable string of unspecified format). An |
|
|
82 | exception is the the node port, whose ID is identical to its node |
|
|
83 | reference. |
56 | |
84 | |
57 | =item node |
85 | =item node |
58 | |
86 | |
59 | A node is a single process containing at least one port - the node |
87 | A node is a single process containing at least one port - the node |
60 | port. You can send messages to node ports to let them create new ports, |
88 | port. You can send messages to node ports to find existing ports or to |
61 | among other things. |
89 | create new ports, among other things. |
62 | |
90 | |
63 | Initially, nodes are either private (single-process only) or hidden |
91 | Nodes are either private (single-process only), slaves (connected to a |
64 | (connected to a master node only). Only when they epxlicitly "become |
92 | master node only) or public nodes (connectable from unrelated nodes). |
65 | public" can you send them messages from unrelated other nodes. |
|
|
66 | |
93 | |
67 | =item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> |
94 | =item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> |
68 | |
95 | |
69 | A noderef is a string that either uniquely identifies a given node (for |
96 | A node reference is a string that either simply identifies the node (for |
70 | private and hidden nodes), or contains a recipe on how to reach a given |
97 | private and slave nodes), or contains a recipe on how to reach a given |
71 | node (for public nodes). |
98 | node (for public nodes). |
72 | |
99 | |
|
|
100 | This recipe is simply a comma-separated list of C<address:port> pairs (for |
|
|
101 | TCP/IP, other protocols might look different). |
|
|
102 | |
|
|
103 | Node references come in two flavours: resolved (containing only numerical |
|
|
104 | addresses) or unresolved (where hostnames are used instead of addresses). |
|
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105 | |
|
|
106 | Before using an unresolved node reference in a message you first have to |
|
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107 | resolve it. |
|
|
108 | |
73 | =back |
109 | =back |
74 | |
110 | |
75 | =head1 VARIABLES/FUNCTIONS |
111 | =head1 VARIABLES/FUNCTIONS |
76 | |
112 | |
77 | =over 4 |
113 | =over 4 |
78 | |
114 | |
79 | =cut |
115 | =cut |
80 | |
116 | |
81 | package AnyEvent::MP; |
117 | package AnyEvent::MP; |
82 | |
118 | |
83 | use AnyEvent::MP::Base; |
119 | use AnyEvent::MP::Kernel; |
84 | |
120 | |
85 | use common::sense; |
121 | use common::sense; |
86 | |
122 | |
87 | use Carp (); |
123 | use Carp (); |
88 | |
124 | |
89 | use AE (); |
125 | use AE (); |
90 | |
126 | |
91 | use base "Exporter"; |
127 | use base "Exporter"; |
92 | |
128 | |
93 | our $VERSION = '0.02'; |
129 | our $VERSION = $AnyEvent::MP::Kernel::VERSION; |
|
|
130 | |
94 | our @EXPORT = qw( |
131 | our @EXPORT = qw( |
95 | NODE $NODE *SELF node_of _any_ |
132 | NODE $NODE *SELF node_of _any_ |
96 | become_slave become_public |
133 | resolve_node initialise_node |
97 | snd rcv mon kil reg psub |
134 | snd rcv mon kil reg psub spawn |
98 | port |
135 | port |
99 | ); |
136 | ); |
100 | |
137 | |
101 | our $SELF; |
138 | our $SELF; |
102 | |
139 | |
… | |
… | |
111 | The C<NODE> function returns, and the C<$NODE> variable contains |
148 | The C<NODE> function returns, and the C<$NODE> variable contains |
112 | the noderef of the local node. The value is initialised by a call |
149 | the noderef of the local node. The value is initialised by a call |
113 | to C<become_public> or C<become_slave>, after which all local port |
150 | to C<become_public> or C<become_slave>, after which all local port |
114 | identifiers become invalid. |
151 | identifiers become invalid. |
115 | |
152 | |
116 | =item $noderef = node_of $portid |
153 | =item $noderef = node_of $port |
117 | |
154 | |
118 | Extracts and returns the noderef from a portid or a noderef. |
155 | Extracts and returns the noderef from a portid or a noderef. |
|
|
156 | |
|
|
157 | =item initialise_node $noderef, $seednode, $seednode... |
|
|
158 | |
|
|
159 | =item initialise_node "slave/", $master, $master... |
|
|
160 | |
|
|
161 | Before a node can talk to other nodes on the network it has to initialise |
|
|
162 | itself - the minimum a node needs to know is it's own name, and optionally |
|
|
163 | it should know the noderefs of some other nodes in the network. |
|
|
164 | |
|
|
165 | This function initialises a node - it must be called exactly once (or |
|
|
166 | never) before calling other AnyEvent::MP functions. |
|
|
167 | |
|
|
168 | All arguments are noderefs, which can be either resolved or unresolved. |
|
|
169 | |
|
|
170 | There are two types of networked nodes, public nodes and slave nodes: |
|
|
171 | |
|
|
172 | =over 4 |
|
|
173 | |
|
|
174 | =item public nodes |
|
|
175 | |
|
|
176 | For public nodes, C<$noderef> must either be a (possibly unresolved) |
|
|
177 | noderef, in which case it will be resolved, or C<undef> (or missing), in |
|
|
178 | which case the noderef will be guessed. |
|
|
179 | |
|
|
180 | Afterwards, the node will bind itself on all endpoints and try to connect |
|
|
181 | to all additional C<$seednodes> that are specified. Seednodes are optional |
|
|
182 | and can be used to quickly bootstrap the node into an existing network. |
|
|
183 | |
|
|
184 | =item slave nodes |
|
|
185 | |
|
|
186 | When the C<$noderef> is the special string C<slave/>, then the node will |
|
|
187 | become a slave node. Slave nodes cannot be contacted from outside and will |
|
|
188 | route most of their traffic to the master node that they attach to. |
|
|
189 | |
|
|
190 | At least one additional noderef is required: The node will try to connect |
|
|
191 | to all of them and will become a slave attached to the first node it can |
|
|
192 | successfully connect to. |
|
|
193 | |
|
|
194 | =back |
|
|
195 | |
|
|
196 | This function will block until all nodes have been resolved and, for slave |
|
|
197 | nodes, until it has successfully established a connection to a master |
|
|
198 | server. |
|
|
199 | |
|
|
200 | Example: become a public node listening on the default node. |
|
|
201 | |
|
|
202 | initialise_node; |
|
|
203 | |
|
|
204 | Example: become a public node, and try to contact some well-known master |
|
|
205 | servers to become part of the network. |
|
|
206 | |
|
|
207 | initialise_node undef, "master1", "master2"; |
|
|
208 | |
|
|
209 | Example: become a public node listening on port C<4041>. |
|
|
210 | |
|
|
211 | initialise_node 4041; |
|
|
212 | |
|
|
213 | Example: become a public node, only visible on localhost port 4044. |
|
|
214 | |
|
|
215 | initialise_node "locahost:4044"; |
|
|
216 | |
|
|
217 | Example: become a slave node to any of the specified master servers. |
|
|
218 | |
|
|
219 | initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net"; |
|
|
220 | |
|
|
221 | =item $cv = resolve_node $noderef |
|
|
222 | |
|
|
223 | Takes an unresolved node reference that may contain hostnames and |
|
|
224 | abbreviated IDs, resolves all of them and returns a resolved node |
|
|
225 | reference. |
|
|
226 | |
|
|
227 | In addition to C<address:port> pairs allowed in resolved noderefs, the |
|
|
228 | following forms are supported: |
|
|
229 | |
|
|
230 | =over 4 |
|
|
231 | |
|
|
232 | =item the empty string |
|
|
233 | |
|
|
234 | An empty-string component gets resolved as if the default port (4040) was |
|
|
235 | specified. |
|
|
236 | |
|
|
237 | =item naked port numbers (e.g. C<1234>) |
|
|
238 | |
|
|
239 | These are resolved by prepending the local nodename and a colon, to be |
|
|
240 | further resolved. |
|
|
241 | |
|
|
242 | =item hostnames (e.g. C<localhost:1234>, C<localhost>) |
|
|
243 | |
|
|
244 | These are resolved by using AnyEvent::DNS to resolve them, optionally |
|
|
245 | looking up SRV records for the C<aemp=4040> port, if no port was |
|
|
246 | specified. |
|
|
247 | |
|
|
248 | =back |
119 | |
249 | |
120 | =item $SELF |
250 | =item $SELF |
121 | |
251 | |
122 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
252 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
123 | blocks. |
253 | blocks. |
… | |
… | |
126 | |
256 | |
127 | Due to some quirks in how perl exports variables, it is impossible to |
257 | Due to some quirks in how perl exports variables, it is impossible to |
128 | just export C<$SELF>, all the symbols called C<SELF> are exported by this |
258 | just export C<$SELF>, all the symbols called C<SELF> are exported by this |
129 | module, but only C<$SELF> is currently used. |
259 | module, but only C<$SELF> is currently used. |
130 | |
260 | |
131 | =item snd $portid, type => @data |
261 | =item snd $port, type => @data |
132 | |
262 | |
133 | =item snd $portid, @msg |
263 | =item snd $port, @msg |
134 | |
264 | |
135 | Send the given message to the given port ID, which can identify either |
265 | Send the given message to the given port ID, which can identify either |
136 | a local or a remote port, and can be either a string or soemthignt hat |
266 | a local or a remote port, and can be either a string or soemthignt hat |
137 | stringifies a sa port ID (such as a port object :). |
267 | stringifies a sa port ID (such as a port object :). |
138 | |
268 | |
… | |
… | |
148 | JSON is used, then only strings, numbers and arrays and hashes consisting |
278 | JSON is used, then only strings, numbers and arrays and hashes consisting |
149 | of those are allowed (no objects). When Storable is used, then anything |
279 | of those are allowed (no objects). When Storable is used, then anything |
150 | that Storable can serialise and deserialise is allowed, and for the local |
280 | that Storable can serialise and deserialise is allowed, and for the local |
151 | node, anything can be passed. |
281 | node, anything can be passed. |
152 | |
282 | |
153 | =item kil $portid[, @reason] |
|
|
154 | |
|
|
155 | Kill the specified port with the given C<@reason>. |
|
|
156 | |
|
|
157 | If no C<@reason> is specified, then the port is killed "normally" (linked |
|
|
158 | ports will not be kileld, or even notified). |
|
|
159 | |
|
|
160 | Otherwise, linked ports get killed with the same reason (second form of |
|
|
161 | C<mon>, see below). |
|
|
162 | |
|
|
163 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
|
|
164 | will be reported as reason C<< die => $@ >>. |
|
|
165 | |
|
|
166 | Transport/communication errors are reported as C<< transport_error => |
|
|
167 | $message >>. |
|
|
168 | |
|
|
169 | =item $guard = mon $portid, $cb->(@reason) |
|
|
170 | |
|
|
171 | =item $guard = mon $portid, $otherport |
|
|
172 | |
|
|
173 | =item $guard = mon $portid, $otherport, @msg |
|
|
174 | |
|
|
175 | Monitor the given port and do something when the port is killed. |
|
|
176 | |
|
|
177 | In the first form, the callback is simply called with any number |
|
|
178 | of C<@reason> elements (no @reason means that the port was deleted |
|
|
179 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
|
|
180 | C<eval> if unsure. |
|
|
181 | |
|
|
182 | In the second form, the other port will be C<kil>'ed with C<@reason>, iff |
|
|
183 | a @reason was specified, i.e. on "normal" kils nothing happens, while |
|
|
184 | under all other conditions, the other port is killed with the same reason. |
|
|
185 | |
|
|
186 | In the last form, a message of the form C<@msg, @reason> will be C<snd>. |
|
|
187 | |
|
|
188 | Example: call a given callback when C<$port> is killed. |
|
|
189 | |
|
|
190 | mon $port, sub { warn "port died because of <@_>\n" }; |
|
|
191 | |
|
|
192 | Example: kill ourselves when C<$port> is killed abnormally. |
|
|
193 | |
|
|
194 | mon $port, $self; |
|
|
195 | |
|
|
196 | Example: send us a restart message another C<$port> is killed. |
|
|
197 | |
|
|
198 | mon $port, $self => "restart"; |
|
|
199 | |
|
|
200 | =cut |
|
|
201 | |
|
|
202 | sub mon { |
|
|
203 | my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift); |
|
|
204 | |
|
|
205 | my $node = $NODE{$noderef} || add_node $noderef; |
|
|
206 | |
|
|
207 | #TODO: ports must not be references |
|
|
208 | if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) { |
|
|
209 | if (@_) { |
|
|
210 | # send a kill info message |
|
|
211 | my (@msg) = ($cb, @_); |
|
|
212 | $cb = sub { snd @msg, @_ }; |
|
|
213 | } else { |
|
|
214 | # simply kill other port |
|
|
215 | my $port = $cb; |
|
|
216 | $cb = sub { kil $port, @_ if @_ }; |
|
|
217 | } |
|
|
218 | } |
|
|
219 | |
|
|
220 | $node->monitor ($port, $cb); |
|
|
221 | |
|
|
222 | defined wantarray |
|
|
223 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
|
|
224 | } |
|
|
225 | |
|
|
226 | =item $guard = mon_guard $port, $ref, $ref... |
|
|
227 | |
|
|
228 | Monitors the given C<$port> and keeps the passed references. When the port |
|
|
229 | is killed, the references will be freed. |
|
|
230 | |
|
|
231 | Optionally returns a guard that will stop the monitoring. |
|
|
232 | |
|
|
233 | This function is useful when you create e.g. timers or other watchers and |
|
|
234 | want to free them when the port gets killed: |
|
|
235 | |
|
|
236 | $port->rcv (start => sub { |
|
|
237 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { |
|
|
238 | undef $timer if 0.9 < rand; |
|
|
239 | }); |
|
|
240 | }); |
|
|
241 | |
|
|
242 | =cut |
|
|
243 | |
|
|
244 | sub mon_guard { |
|
|
245 | my ($port, @refs) = @_; |
|
|
246 | |
|
|
247 | mon $port, sub { 0 && @refs } |
|
|
248 | } |
|
|
249 | |
|
|
250 | =item lnk $port1, $port2 |
|
|
251 | |
|
|
252 | Link two ports. This is simply a shorthand for: |
|
|
253 | |
|
|
254 | mon $port1, $port2; |
|
|
255 | mon $port2, $port1; |
|
|
256 | |
|
|
257 | It means that if either one is killed abnormally, the other one gets |
|
|
258 | killed as well. |
|
|
259 | |
|
|
260 | =item $local_port = port |
283 | =item $local_port = port |
261 | |
284 | |
262 | Create a new local port object that supports message matching. |
285 | Create a new local port object that can be used either as a pattern |
|
|
286 | matching port ("full port") or a single-callback port ("miniport"), |
|
|
287 | depending on how C<rcv> callbacks are bound to the object. |
263 | |
288 | |
264 | =item $portid = port { my @msg = @_; $finished } |
289 | =item $port = port { my @msg = @_; $finished } |
265 | |
290 | |
266 | Creates a "mini port", that is, a very lightweight port without any |
291 | Creates a "miniport", that is, a very lightweight port without any pattern |
267 | pattern matching behind it, and returns its ID. |
292 | matching behind it, and returns its ID. Semantically the same as creating |
|
|
293 | a port and calling C<rcv $port, $callback> on it. |
268 | |
294 | |
269 | The block will be called for every message received on the port. When the |
295 | The block will be called for every message received on the port. When the |
270 | callback returns a true value its job is considered "done" and the port |
296 | callback returns a true value its job is considered "done" and the port |
271 | will be destroyed. Otherwise it will stay alive. |
297 | will be destroyed. Otherwise it will stay alive. |
272 | |
298 | |
273 | The message will be passed as-is, no extra argument (i.e. no port id) will |
299 | The message will be passed as-is, no extra argument (i.e. no port id) will |
274 | be passed to the callback. |
300 | be passed to the callback. |
275 | |
301 | |
276 | If you need the local port id in the callback, this works nicely: |
302 | If you need the local port id in the callback, this works nicely: |
277 | |
303 | |
278 | my $port; $port = miniport { |
304 | my $port; $port = port { |
279 | snd $otherport, reply => $port; |
305 | snd $otherport, reply => $port; |
280 | }; |
306 | }; |
281 | |
307 | |
282 | =cut |
308 | =cut |
|
|
309 | |
|
|
310 | sub rcv($@); |
283 | |
311 | |
284 | sub port(;&) { |
312 | sub port(;&) { |
285 | my $id = "$UNIQ." . $ID++; |
313 | my $id = "$UNIQ." . $ID++; |
286 | my $port = "$NODE#$id"; |
314 | my $port = "$NODE#$id"; |
287 | |
315 | |
288 | if (@_) { |
316 | if (@_) { |
|
|
317 | rcv $port, shift; |
|
|
318 | } else { |
|
|
319 | $PORT{$id} = sub { }; # nop |
|
|
320 | } |
|
|
321 | |
|
|
322 | $port |
|
|
323 | } |
|
|
324 | |
|
|
325 | =item reg $port, $name |
|
|
326 | |
|
|
327 | =item reg $name |
|
|
328 | |
|
|
329 | Registers the given port (or C<$SELF><<< if missing) under the name |
|
|
330 | C<$name>. If the name already exists it is replaced. |
|
|
331 | |
|
|
332 | A port can only be registered under one well known name. |
|
|
333 | |
|
|
334 | A port automatically becomes unregistered when it is killed. |
|
|
335 | |
|
|
336 | =cut |
|
|
337 | |
|
|
338 | sub reg(@) { |
|
|
339 | my $port = @_ > 1 ? shift : $SELF || Carp::croak 'reg: called with one argument only, but $SELF not set,'; |
|
|
340 | |
|
|
341 | $REG{$_[0]} = $port; |
|
|
342 | } |
|
|
343 | |
|
|
344 | =item rcv $port, $callback->(@msg) |
|
|
345 | |
|
|
346 | Replaces the callback on the specified miniport (after converting it to |
|
|
347 | one if required). |
|
|
348 | |
|
|
349 | =item rcv $port, tagstring => $callback->(@msg), ... |
|
|
350 | |
|
|
351 | =item rcv $port, $smartmatch => $callback->(@msg), ... |
|
|
352 | |
|
|
353 | =item rcv $port, [$smartmatch...] => $callback->(@msg), ... |
|
|
354 | |
|
|
355 | Register callbacks to be called on matching messages on the given full |
|
|
356 | port (after converting it to one if required) and return the port. |
|
|
357 | |
|
|
358 | The callback has to return a true value when its work is done, after |
|
|
359 | which is will be removed, or a false value in which case it will stay |
|
|
360 | registered. |
|
|
361 | |
|
|
362 | The global C<$SELF> (exported by this module) contains C<$port> while |
|
|
363 | executing the callback. |
|
|
364 | |
|
|
365 | Runtime errors during callback execution will result in the port being |
|
|
366 | C<kil>ed. |
|
|
367 | |
|
|
368 | If the match is an array reference, then it will be matched against the |
|
|
369 | first elements of the message, otherwise only the first element is being |
|
|
370 | matched. |
|
|
371 | |
|
|
372 | Any element in the match that is specified as C<_any_> (a function |
|
|
373 | exported by this module) matches any single element of the message. |
|
|
374 | |
|
|
375 | While not required, it is highly recommended that the first matching |
|
|
376 | element is a string identifying the message. The one-string-only match is |
|
|
377 | also the most efficient match (by far). |
|
|
378 | |
|
|
379 | Example: create a port and bind receivers on it in one go. |
|
|
380 | |
|
|
381 | my $port = rcv port, |
|
|
382 | msg1 => sub { ...; 0 }, |
|
|
383 | msg2 => sub { ...; 0 }, |
|
|
384 | ; |
|
|
385 | |
|
|
386 | Example: create a port, bind receivers and send it in a message elsewhere |
|
|
387 | in one go: |
|
|
388 | |
|
|
389 | snd $otherport, reply => |
|
|
390 | rcv port, |
|
|
391 | msg1 => sub { ...; 0 }, |
|
|
392 | ... |
|
|
393 | ; |
|
|
394 | |
|
|
395 | =cut |
|
|
396 | |
|
|
397 | sub rcv($@) { |
|
|
398 | my $port = shift; |
|
|
399 | my ($noderef, $portid) = split /#/, $port, 2; |
|
|
400 | |
|
|
401 | ($NODE{$noderef} || add_node $noderef) == $NODE{""} |
|
|
402 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
|
|
403 | |
|
|
404 | if (@_ == 1) { |
289 | my $cb = shift; |
405 | my $cb = shift; |
|
|
406 | delete $PORT_DATA{$portid}; |
290 | $PORT{$id} = sub { |
407 | $PORT{$portid} = sub { |
291 | local $SELF = $port; |
408 | local $SELF = $port; |
292 | eval { |
409 | eval { |
293 | &$cb |
410 | &$cb |
294 | and kil $id; |
411 | and kil $port; |
295 | }; |
412 | }; |
296 | _self_die if $@; |
413 | _self_die if $@; |
297 | }; |
414 | }; |
298 | } else { |
415 | } else { |
|
|
416 | my $self = $PORT_DATA{$portid} ||= do { |
299 | my $self = bless { |
417 | my $self = bless { |
300 | id => "$NODE#$id", |
418 | id => $port, |
301 | }, "AnyEvent::MP::Port"; |
419 | }, "AnyEvent::MP::Port"; |
302 | |
420 | |
303 | $PORT_DATA{$id} = $self; |
|
|
304 | $PORT{$id} = sub { |
421 | $PORT{$portid} = sub { |
305 | local $SELF = $port; |
422 | local $SELF = $port; |
306 | |
423 | |
307 | eval { |
424 | eval { |
308 | for (@{ $self->{rc0}{$_[0]} }) { |
425 | for (@{ $self->{rc0}{$_[0]} }) { |
309 | $_ && &{$_->[0]} |
426 | $_ && &{$_->[0]} |
310 | && undef $_; |
427 | && undef $_; |
311 | } |
428 | } |
312 | |
429 | |
313 | for (@{ $self->{rcv}{$_[0]} }) { |
430 | for (@{ $self->{rcv}{$_[0]} }) { |
314 | $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1] |
431 | $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1] |
315 | && &{$_->[0]} |
432 | && &{$_->[0]} |
316 | && undef $_; |
433 | && undef $_; |
317 | } |
434 | } |
318 | |
435 | |
319 | for (@{ $self->{any} }) { |
436 | for (@{ $self->{any} }) { |
320 | $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1] |
437 | $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1] |
321 | && &{$_->[0]} |
438 | && &{$_->[0]} |
322 | && undef $_; |
439 | && undef $_; |
|
|
440 | } |
323 | } |
441 | }; |
|
|
442 | _self_die if $@; |
324 | }; |
443 | }; |
325 | _self_die if $@; |
444 | |
|
|
445 | $self |
326 | }; |
446 | }; |
327 | } |
|
|
328 | |
447 | |
329 | $port |
|
|
330 | } |
|
|
331 | |
|
|
332 | =item reg $portid, $name |
|
|
333 | |
|
|
334 | Registers the given port under the name C<$name>. If the name already |
|
|
335 | exists it is replaced. |
|
|
336 | |
|
|
337 | A port can only be registered under one well known name. |
|
|
338 | |
|
|
339 | A port automatically becomes unregistered when it is killed. |
|
|
340 | |
|
|
341 | =cut |
|
|
342 | |
|
|
343 | sub reg(@) { |
|
|
344 | my ($portid, $name) = @_; |
|
|
345 | |
|
|
346 | $REG{$name} = $portid; |
|
|
347 | } |
|
|
348 | |
|
|
349 | =item rcv $portid, tagstring => $callback->(@msg), ... |
|
|
350 | |
|
|
351 | =item rcv $portid, $smartmatch => $callback->(@msg), ... |
|
|
352 | |
|
|
353 | =item rcv $portid, [$smartmatch...] => $callback->(@msg), ... |
|
|
354 | |
|
|
355 | Register callbacks to be called on matching messages on the given port. |
|
|
356 | |
|
|
357 | The callback has to return a true value when its work is done, after |
|
|
358 | which is will be removed, or a false value in which case it will stay |
|
|
359 | registered. |
|
|
360 | |
|
|
361 | The global C<$SELF> (exported by this module) contains C<$portid> while |
|
|
362 | executing the callback. |
|
|
363 | |
|
|
364 | Runtime errors wdurign callback execution will result in the port being |
|
|
365 | C<kil>ed. |
|
|
366 | |
|
|
367 | If the match is an array reference, then it will be matched against the |
|
|
368 | first elements of the message, otherwise only the first element is being |
|
|
369 | matched. |
|
|
370 | |
|
|
371 | Any element in the match that is specified as C<_any_> (a function |
|
|
372 | exported by this module) matches any single element of the message. |
|
|
373 | |
|
|
374 | While not required, it is highly recommended that the first matching |
|
|
375 | element is a string identifying the message. The one-string-only match is |
|
|
376 | also the most efficient match (by far). |
|
|
377 | |
|
|
378 | =cut |
|
|
379 | |
|
|
380 | sub rcv($@) { |
|
|
381 | my ($noderef, $port) = split /#/, shift, 2; |
|
|
382 | |
|
|
383 | ($NODE{$noderef} || add_node $noderef) == $NODE{""} |
|
|
384 | or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught"; |
|
|
385 | |
|
|
386 | my $self = $PORT_DATA{$port} |
|
|
387 | or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught"; |
|
|
388 | |
|
|
389 | "AnyEvent::MP::Port" eq ref $self |
448 | "AnyEvent::MP::Port" eq ref $self |
390 | or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught"; |
449 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
391 | |
450 | |
392 | while (@_) { |
451 | while (@_) { |
393 | my ($match, $cb) = splice @_, 0, 2; |
452 | my ($match, $cb) = splice @_, 0, 2; |
394 | |
453 | |
395 | if (!ref $match) { |
454 | if (!ref $match) { |
396 | push @{ $self->{rc0}{$match} }, [$cb]; |
455 | push @{ $self->{rc0}{$match} }, [$cb]; |
397 | } elsif (("ARRAY" eq ref $match && !ref $match->[0])) { |
456 | } elsif (("ARRAY" eq ref $match && !ref $match->[0])) { |
398 | my ($type, @match) = @$match; |
457 | my ($type, @match) = @$match; |
399 | @match |
458 | @match |
400 | ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match] |
459 | ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match] |
401 | : push @{ $self->{rc0}{$match->[0]} }, [$cb]; |
460 | : push @{ $self->{rc0}{$match->[0]} }, [$cb]; |
402 | } else { |
461 | } else { |
403 | push @{ $self->{any} }, [$cb, $match]; |
462 | push @{ $self->{any} }, [$cb, $match]; |
|
|
463 | } |
404 | } |
464 | } |
405 | } |
465 | } |
|
|
466 | |
|
|
467 | $port |
406 | } |
468 | } |
407 | |
469 | |
408 | =item $closure = psub { BLOCK } |
470 | =item $closure = psub { BLOCK } |
409 | |
471 | |
410 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
472 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
… | |
… | |
441 | $res |
503 | $res |
442 | } |
504 | } |
443 | } |
505 | } |
444 | } |
506 | } |
445 | |
507 | |
446 | =back |
508 | =item $guard = mon $port, $cb->(@reason) |
447 | |
509 | |
448 | =head1 FUNCTIONS FOR NODES |
510 | =item $guard = mon $port, $rcvport |
449 | |
511 | |
450 | =over 4 |
512 | =item $guard = mon $port |
451 | |
513 | |
452 | =item become_public endpoint... |
514 | =item $guard = mon $port, $rcvport, @msg |
453 | |
515 | |
454 | Tells the node to become a public node, i.e. reachable from other nodes. |
516 | Monitor the given port and do something when the port is killed or |
|
|
517 | messages to it were lost, and optionally return a guard that can be used |
|
|
518 | to stop monitoring again. |
455 | |
519 | |
456 | If no arguments are given, or the first argument is C<undef>, then |
520 | C<mon> effectively guarantees that, in the absence of hardware failures, |
457 | AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the |
521 | that after starting the monitor, either all messages sent to the port |
458 | local nodename resolves to. |
522 | will arrive, or the monitoring action will be invoked after possible |
|
|
523 | message loss has been detected. No messages will be lost "in between" |
|
|
524 | (after the first lost message no further messages will be received by the |
|
|
525 | port). After the monitoring action was invoked, further messages might get |
|
|
526 | delivered again. |
459 | |
527 | |
460 | Otherwise the first argument must be an array-reference with transport |
528 | In the first form (callback), the callback is simply called with any |
461 | endpoints ("ip:port", "hostname:port") or port numbers (in which case the |
529 | number of C<@reason> elements (no @reason means that the port was deleted |
462 | local nodename is used as hostname). The endpoints are all resolved and |
530 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
463 | will become the node reference. |
531 | C<eval> if unsure. |
464 | |
532 | |
|
|
533 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
534 | will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on |
|
|
535 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
536 | port is killed with the same reason. |
|
|
537 | |
|
|
538 | The third form (kill self) is the same as the second form, except that |
|
|
539 | C<$rvport> defaults to C<$SELF>. |
|
|
540 | |
|
|
541 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
542 | C<snd>. |
|
|
543 | |
|
|
544 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
545 | a local port (or callback). The reason is that kill messages might get |
|
|
546 | lost, just like any other message. Another less obvious reason is that |
|
|
547 | even monitoring requests can get lost (for exmaple, when the connection |
|
|
548 | to the other node goes down permanently). When monitoring a port locally |
|
|
549 | these problems do not exist. |
|
|
550 | |
|
|
551 | Example: call a given callback when C<$port> is killed. |
|
|
552 | |
|
|
553 | mon $port, sub { warn "port died because of <@_>\n" }; |
|
|
554 | |
|
|
555 | Example: kill ourselves when C<$port> is killed abnormally. |
|
|
556 | |
|
|
557 | mon $port; |
|
|
558 | |
|
|
559 | Example: send us a restart message when another C<$port> is killed. |
|
|
560 | |
|
|
561 | mon $port, $self => "restart"; |
|
|
562 | |
465 | =cut |
563 | =cut |
|
|
564 | |
|
|
565 | sub mon { |
|
|
566 | my ($noderef, $port) = split /#/, shift, 2; |
|
|
567 | |
|
|
568 | my $node = $NODE{$noderef} || add_node $noderef; |
|
|
569 | |
|
|
570 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
|
|
571 | |
|
|
572 | unless (ref $cb) { |
|
|
573 | if (@_) { |
|
|
574 | # send a kill info message |
|
|
575 | my (@msg) = ($cb, @_); |
|
|
576 | $cb = sub { snd @msg, @_ }; |
|
|
577 | } else { |
|
|
578 | # simply kill other port |
|
|
579 | my $port = $cb; |
|
|
580 | $cb = sub { kil $port, @_ if @_ }; |
|
|
581 | } |
|
|
582 | } |
|
|
583 | |
|
|
584 | $node->monitor ($port, $cb); |
|
|
585 | |
|
|
586 | defined wantarray |
|
|
587 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
|
|
588 | } |
|
|
589 | |
|
|
590 | =item $guard = mon_guard $port, $ref, $ref... |
|
|
591 | |
|
|
592 | Monitors the given C<$port> and keeps the passed references. When the port |
|
|
593 | is killed, the references will be freed. |
|
|
594 | |
|
|
595 | Optionally returns a guard that will stop the monitoring. |
|
|
596 | |
|
|
597 | This function is useful when you create e.g. timers or other watchers and |
|
|
598 | want to free them when the port gets killed: |
|
|
599 | |
|
|
600 | $port->rcv (start => sub { |
|
|
601 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { |
|
|
602 | undef $timer if 0.9 < rand; |
|
|
603 | }); |
|
|
604 | }); |
|
|
605 | |
|
|
606 | =cut |
|
|
607 | |
|
|
608 | sub mon_guard { |
|
|
609 | my ($port, @refs) = @_; |
|
|
610 | |
|
|
611 | #TODO: mon-less form? |
|
|
612 | |
|
|
613 | mon $port, sub { 0 && @refs } |
|
|
614 | } |
|
|
615 | |
|
|
616 | =item kil $port[, @reason] |
|
|
617 | |
|
|
618 | Kill the specified port with the given C<@reason>. |
|
|
619 | |
|
|
620 | If no C<@reason> is specified, then the port is killed "normally" (linked |
|
|
621 | ports will not be kileld, or even notified). |
|
|
622 | |
|
|
623 | Otherwise, linked ports get killed with the same reason (second form of |
|
|
624 | C<mon>, see below). |
|
|
625 | |
|
|
626 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
|
|
627 | will be reported as reason C<< die => $@ >>. |
|
|
628 | |
|
|
629 | Transport/communication errors are reported as C<< transport_error => |
|
|
630 | $message >>. |
|
|
631 | |
|
|
632 | =cut |
|
|
633 | |
|
|
634 | =item $port = spawn $node, $initfunc[, @initdata] |
|
|
635 | |
|
|
636 | Creates a port on the node C<$node> (which can also be a port ID, in which |
|
|
637 | case it's the node where that port resides). |
|
|
638 | |
|
|
639 | The port ID of the newly created port is return immediately, and it is |
|
|
640 | permissible to immediately start sending messages or monitor the port. |
|
|
641 | |
|
|
642 | After the port has been created, the init function is |
|
|
643 | called. This function must be a fully-qualified function name |
|
|
644 | (e.g. C<MyApp::Chat::Server::init>). To specify a function in the main |
|
|
645 | program, use C<::name>. |
|
|
646 | |
|
|
647 | If the function doesn't exist, then the node tries to C<require> |
|
|
648 | the package, then the package above the package and so on (e.g. |
|
|
649 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
|
|
650 | exists or it runs out of package names. |
|
|
651 | |
|
|
652 | The init function is then called with the newly-created port as context |
|
|
653 | object (C<$SELF>) and the C<@initdata> values as arguments. |
|
|
654 | |
|
|
655 | A common idiom is to pass your own port, monitor the spawned port, and |
|
|
656 | in the init function, monitor the original port. This two-way monitoring |
|
|
657 | ensures that both ports get cleaned up when there is a problem. |
|
|
658 | |
|
|
659 | Example: spawn a chat server port on C<$othernode>. |
|
|
660 | |
|
|
661 | # this node, executed from within a port context: |
|
|
662 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
|
|
663 | mon $server; |
|
|
664 | |
|
|
665 | # init function on C<$othernode> |
|
|
666 | sub connect { |
|
|
667 | my ($srcport) = @_; |
|
|
668 | |
|
|
669 | mon $srcport; |
|
|
670 | |
|
|
671 | rcv $SELF, sub { |
|
|
672 | ... |
|
|
673 | }; |
|
|
674 | } |
|
|
675 | |
|
|
676 | =cut |
|
|
677 | |
|
|
678 | sub _spawn { |
|
|
679 | my $port = shift; |
|
|
680 | my $init = shift; |
|
|
681 | |
|
|
682 | local $SELF = "$NODE#$port"; |
|
|
683 | eval { |
|
|
684 | &{ load_func $init } |
|
|
685 | }; |
|
|
686 | _self_die if $@; |
|
|
687 | } |
|
|
688 | |
|
|
689 | sub spawn(@) { |
|
|
690 | my ($noderef, undef) = split /#/, shift, 2; |
|
|
691 | |
|
|
692 | my $id = "$RUNIQ." . $ID++; |
|
|
693 | |
|
|
694 | $_[0] =~ /::/ |
|
|
695 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
|
|
696 | |
|
|
697 | ($NODE{$noderef} || add_node $noderef) |
|
|
698 | ->send (["", "AnyEvent::MP::_spawn" => $id, @_]); |
|
|
699 | |
|
|
700 | "$noderef#$id" |
|
|
701 | } |
466 | |
702 | |
467 | =back |
703 | =back |
468 | |
704 | |
469 | =head1 NODE MESSAGES |
705 | =head1 NODE MESSAGES |
470 | |
706 | |
471 | Nodes understand the following messages sent to them. Many of them take |
707 | Nodes understand the following messages sent to them. Many of them take |
472 | arguments called C<@reply>, which will simply be used to compose a reply |
708 | arguments called C<@reply>, which will simply be used to compose a reply |
473 | message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and |
709 | message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and |
474 | the remaining arguments are simply the message data. |
710 | the remaining arguments are simply the message data. |
475 | |
711 | |
|
|
712 | While other messages exist, they are not public and subject to change. |
|
|
713 | |
476 | =over 4 |
714 | =over 4 |
477 | |
715 | |
478 | =cut |
716 | =cut |
479 | |
717 | |
480 | =item lookup => $name, @reply |
718 | =item lookup => $name, @reply |
… | |
… | |
508 | snd $NODE, time => $myport, timereply => 1, 2; |
746 | snd $NODE, time => $myport, timereply => 1, 2; |
509 | # => snd $myport, timereply => 1, 2, <time> |
747 | # => snd $myport, timereply => 1, 2, <time> |
510 | |
748 | |
511 | =back |
749 | =back |
512 | |
750 | |
|
|
751 | =head1 AnyEvent::MP vs. Distributed Erlang |
|
|
752 | |
|
|
753 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
|
|
754 | == aemp node, Erlang process == aemp port), so many of the documents and |
|
|
755 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
|
|
756 | sample: |
|
|
757 | |
|
|
758 | http://www.Erlang.se/doc/programming_rules.shtml |
|
|
759 | http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
|
|
760 | http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6 |
|
|
761 | http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
|
|
762 | |
|
|
763 | Despite the similarities, there are also some important differences: |
|
|
764 | |
|
|
765 | =over 4 |
|
|
766 | |
|
|
767 | =item * Node references contain the recipe on how to contact them. |
|
|
768 | |
|
|
769 | Erlang relies on special naming and DNS to work everywhere in the |
|
|
770 | same way. AEMP relies on each node knowing it's own address(es), with |
|
|
771 | convenience functionality. |
|
|
772 | |
|
|
773 | This means that AEMP requires a less tightly controlled environment at the |
|
|
774 | cost of longer node references and a slightly higher management overhead. |
|
|
775 | |
|
|
776 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
|
|
777 | |
|
|
778 | Erlang uses processes that selctively receive messages, and therefore |
|
|
779 | needs a queue. AEMP is event based, queuing messages would serve no useful |
|
|
780 | purpose. |
|
|
781 | |
|
|
782 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
|
|
783 | |
|
|
784 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
|
|
785 | |
|
|
786 | Sending messages in Erlang is synchronous and blocks the process. AEMP |
|
|
787 | sends are immediate, connection establishment is handled in the |
|
|
788 | background. |
|
|
789 | |
|
|
790 | =item * Erlang can silently lose messages, AEMP cannot. |
|
|
791 | |
|
|
792 | Erlang makes few guarantees on messages delivery - messages can get lost |
|
|
793 | without any of the processes realising it (i.e. you send messages a, b, |
|
|
794 | and c, and the other side only receives messages a and c). |
|
|
795 | |
|
|
796 | AEMP guarantees correct ordering, and the guarantee that there are no |
|
|
797 | holes in the message sequence. |
|
|
798 | |
|
|
799 | =item * In Erlang, processes can be declared dead and later be found to be |
|
|
800 | alive. |
|
|
801 | |
|
|
802 | In Erlang it can happen that a monitored process is declared dead and |
|
|
803 | linked processes get killed, but later it turns out that the process is |
|
|
804 | still alive - and can receive messages. |
|
|
805 | |
|
|
806 | In AEMP, when port monitoring detects a port as dead, then that port will |
|
|
807 | eventually be killed - it cannot happen that a node detects a port as dead |
|
|
808 | and then later sends messages to it, finding it is still alive. |
|
|
809 | |
|
|
810 | =item * Erlang can send messages to the wrong port, AEMP does not. |
|
|
811 | |
|
|
812 | In Erlang it is quite possible that a node that restarts reuses a process |
|
|
813 | ID known to other nodes for a completely different process, causing |
|
|
814 | messages destined for that process to end up in an unrelated process. |
|
|
815 | |
|
|
816 | AEMP never reuses port IDs, so old messages or old port IDs floating |
|
|
817 | around in the network will not be sent to an unrelated port. |
|
|
818 | |
|
|
819 | =item * Erlang uses unprotected connections, AEMP uses secure |
|
|
820 | authentication and can use TLS. |
|
|
821 | |
|
|
822 | AEMP can use a proven protocol - SSL/TLS - to protect connections and |
|
|
823 | securely authenticate nodes. |
|
|
824 | |
|
|
825 | =item * The AEMP protocol is optimised for both text-based and binary |
|
|
826 | communications. |
|
|
827 | |
|
|
828 | The AEMP protocol, unlike the Erlang protocol, supports both |
|
|
829 | language-independent text-only protocols (good for debugging) and binary, |
|
|
830 | language-specific serialisers (e.g. Storable). |
|
|
831 | |
|
|
832 | It has also been carefully designed to be implementable in other languages |
|
|
833 | with a minimum of work while gracefully degrading fucntionality to make the |
|
|
834 | protocol simple. |
|
|
835 | |
|
|
836 | =item * AEMP has more flexible monitoring options than Erlang. |
|
|
837 | |
|
|
838 | In Erlang, you can chose to receive I<all> exit signals as messages |
|
|
839 | or I<none>, there is no in-between, so monitoring single processes is |
|
|
840 | difficult to implement. Monitoring in AEMP is more flexible than in |
|
|
841 | Erlang, as one can choose between automatic kill, exit message or callback |
|
|
842 | on a per-process basis. |
|
|
843 | |
|
|
844 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
|
|
845 | |
|
|
846 | Monitoring in Erlang is not an indicator of process death/crashes, |
|
|
847 | as linking is (except linking is unreliable in Erlang). |
|
|
848 | |
|
|
849 | In AEMP, you don't "look up" registered port names or send to named ports |
|
|
850 | that might or might not be persistent. Instead, you normally spawn a port |
|
|
851 | on the remote node. The init function monitors the you, and you monitor |
|
|
852 | the remote port. Since both monitors are local to the node, they are much |
|
|
853 | more reliable. |
|
|
854 | |
|
|
855 | This also saves round-trips and avoids sending messages to the wrong port |
|
|
856 | (hard to do in Erlang). |
|
|
857 | |
|
|
858 | =back |
|
|
859 | |
|
|
860 | =head1 RATIONALE |
|
|
861 | |
|
|
862 | =over 4 |
|
|
863 | |
|
|
864 | =item Why strings for ports and noderefs, why not objects? |
|
|
865 | |
|
|
866 | We considered "objects", but found that the actual number of methods |
|
|
867 | thatc an be called are very low. Since port IDs and noderefs travel over |
|
|
868 | the network frequently, the serialising/deserialising would add lots of |
|
|
869 | overhead, as well as having to keep a proxy object. |
|
|
870 | |
|
|
871 | Strings can easily be printed, easily serialised etc. and need no special |
|
|
872 | procedures to be "valid". |
|
|
873 | |
|
|
874 | =item Why favour JSON, why not real serialising format such as Storable? |
|
|
875 | |
|
|
876 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
|
|
877 | format, but currently there is no way to make a node use Storable by |
|
|
878 | default. |
|
|
879 | |
|
|
880 | The default framing protocol is JSON because a) JSON::XS is many times |
|
|
881 | faster for small messages and b) most importantly, after years of |
|
|
882 | experience we found that object serialisation is causing more problems |
|
|
883 | than it gains: Just like function calls, objects simply do not travel |
|
|
884 | easily over the network, mostly because they will always be a copy, so you |
|
|
885 | always have to re-think your design. |
|
|
886 | |
|
|
887 | Keeping your messages simple, concentrating on data structures rather than |
|
|
888 | objects, will keep your messages clean, tidy and efficient. |
|
|
889 | |
|
|
890 | =back |
|
|
891 | |
513 | =head1 SEE ALSO |
892 | =head1 SEE ALSO |
514 | |
893 | |
515 | L<AnyEvent>. |
894 | L<AnyEvent>. |
516 | |
895 | |
517 | =head1 AUTHOR |
896 | =head1 AUTHOR |