1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | AnyEvent::MP - multi-processing/message-passing framework |
3 | AnyEvent::MP - erlang-style multi-processing/message-passing framework |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use AnyEvent::MP; |
7 | use AnyEvent::MP; |
8 | |
8 | |
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30 | rcv $port, pong => sub { warn "pong received\n" }; |
30 | rcv $port, pong => sub { warn "pong received\n" }; |
31 | |
31 | |
32 | # create a port on another node |
32 | # create a port on another node |
33 | my $port = spawn $node, $initfunc, @initdata; |
33 | my $port = spawn $node, $initfunc, @initdata; |
34 | |
34 | |
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35 | # destroy a port again |
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36 | kil $port; # "normal" kill |
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37 | kil $port, my_error => "everything is broken"; # error kill |
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38 | |
35 | # monitoring |
39 | # monitoring |
36 | mon $port, $cb->(@msg) # callback is invoked on death |
40 | mon $localport, $cb->(@msg) # callback is invoked on death |
37 | mon $port, $otherport # kill otherport on abnormal death |
41 | mon $localport, $otherport # kill otherport on abnormal death |
38 | mon $port, $otherport, @msg # send message on death |
42 | mon $localport, $otherport, @msg # send message on death |
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43 | |
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44 | # temporarily execute code in port context |
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45 | peval $port, sub { die "kill the port!" }; |
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46 | |
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47 | # execute callbacks in $SELF port context |
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48 | my $timer = AE::timer 1, 0, psub { |
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49 | die "kill the port, delayed"; |
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50 | }; |
39 | |
51 | |
40 | =head1 CURRENT STATUS |
52 | =head1 CURRENT STATUS |
41 | |
53 | |
42 | bin/aemp - stable. |
54 | bin/aemp - stable. |
43 | AnyEvent::MP - stable API, should work. |
55 | AnyEvent::MP - stable API, should work. |
44 | AnyEvent::MP::Intro - explains most concepts. |
56 | AnyEvent::MP::Intro - explains most concepts. |
45 | AnyEvent::MP::Kernel - mostly stable. |
57 | AnyEvent::MP::Kernel - mostly stable API. |
46 | AnyEvent::MP::Global - stable but incomplete, protocol not yet final. |
58 | AnyEvent::MP::Global - stable API. |
47 | |
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48 | stay tuned. |
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49 | |
59 | |
50 | =head1 DESCRIPTION |
60 | =head1 DESCRIPTION |
51 | |
61 | |
52 | This module (-family) implements a simple message passing framework. |
62 | This module (-family) implements a simple message passing framework. |
53 | |
63 | |
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68 | |
78 | |
69 | Ports allow you to register C<rcv> handlers that can match all or just |
79 | Ports allow you to register C<rcv> handlers that can match all or just |
70 | some messages. Messages send to ports will not be queued, regardless of |
80 | some messages. Messages send to ports will not be queued, regardless of |
71 | anything was listening for them or not. |
81 | anything was listening for them or not. |
72 | |
82 | |
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83 | Ports are represented by (printable) strings called "port IDs". |
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84 | |
73 | =item port ID - C<nodeid#portname> |
85 | =item port ID - C<nodeid#portname> |
74 | |
86 | |
75 | A port ID is the concatenation of a node ID, a hash-mark (C<#>) as |
87 | A port ID is the concatenation of a node ID, a hash-mark (C<#>) |
76 | separator, and a port name (a printable string of unspecified format). |
88 | as separator, and a port name (a printable string of unspecified |
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89 | format created by AnyEvent::MP). |
77 | |
90 | |
78 | =item node |
91 | =item node |
79 | |
92 | |
80 | A node is a single process containing at least one port - the node port, |
93 | A node is a single process containing at least one port - the node port, |
81 | which enables nodes to manage each other remotely, and to create new |
94 | which enables nodes to manage each other remotely, and to create new |
82 | ports. |
95 | ports. |
83 | |
96 | |
84 | Nodes are either public (have one or more listening ports) or private |
97 | Nodes are either public (have one or more listening ports) or private |
85 | (no listening ports). Private nodes cannot talk to other private nodes |
98 | (no listening ports). Private nodes cannot talk to other private nodes |
86 | currently. |
99 | currently, but all nodes can talk to public nodes. |
87 | |
100 | |
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101 | Nodes is represented by (printable) strings called "node IDs". |
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102 | |
88 | =item node ID - C<[a-za-Z0-9_\-.:]+> |
103 | =item node ID - C<[A-Za-z0-9_\-.:]*> |
89 | |
104 | |
90 | A node ID is a string that uniquely identifies the node within a |
105 | A node ID is a string that uniquely identifies the node within a |
91 | network. Depending on the configuration used, node IDs can look like a |
106 | network. Depending on the configuration used, node IDs can look like a |
92 | hostname, a hostname and a port, or a random string. AnyEvent::MP itself |
107 | hostname, a hostname and a port, or a random string. AnyEvent::MP itself |
93 | doesn't interpret node IDs in any way. |
108 | doesn't interpret node IDs in any way except to uniquely identify a node. |
94 | |
109 | |
95 | =item binds - C<ip:port> |
110 | =item binds - C<ip:port> |
96 | |
111 | |
97 | Nodes can only talk to each other by creating some kind of connection to |
112 | Nodes can only talk to each other by creating some kind of connection to |
98 | each other. To do this, nodes should listen on one or more local transport |
113 | each other. To do this, nodes should listen on one or more local transport |
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114 | endpoints - binds. |
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115 | |
99 | endpoints - binds. Currently, only standard C<ip:port> specifications can |
116 | Currently, only standard C<ip:port> specifications can be used, which |
100 | be used, which specify TCP ports to listen on. |
117 | specify TCP ports to listen on. So a bind is basically just a tcp socket |
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118 | in listening mode thta accepts conenctions form other nodes. |
101 | |
119 | |
102 | =item seed nodes |
120 | =item seed nodes |
103 | |
121 | |
104 | When a node starts, it knows nothing about the network. To teach the node |
122 | When a node starts, it knows nothing about the network it is in - it |
105 | about the network it first has to contact some other node within the |
123 | needs to connect to at least one other node that is already in the |
106 | network. This node is called a seed. |
124 | network. These other nodes are called "seed nodes". |
107 | |
125 | |
108 | Apart from the fact that other nodes know them as seed nodes and they have |
126 | Seed nodes themselves are not special - they are seed nodes only because |
109 | to have fixed listening addresses, seed nodes are perfectly normal nodes - |
127 | some other node I<uses> them as such, but any node can be used as seed |
110 | any node can function as a seed node for others. |
128 | node for other nodes, and eahc node cna use a different set of seed nodes. |
111 | |
129 | |
112 | In addition to discovering the network, seed nodes are also used to |
130 | In addition to discovering the network, seed nodes are also used to |
113 | maintain the network and to connect nodes that otherwise would have |
131 | maintain the network - all nodes using the same seed node form are part of |
114 | trouble connecting. They form the backbone of the AnyEvent::MP network. |
132 | the same network. If a network is split into multiple subnets because e.g. |
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133 | the network link between the parts goes down, then using the same seed |
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134 | nodes for all nodes ensures that eventually the subnets get merged again. |
115 | |
135 | |
116 | Seed nodes are expected to be long-running, and at least one seed node |
136 | Seed nodes are expected to be long-running, and at least one seed node |
117 | should always be available. |
137 | should always be available. They should also be relatively responsive - a |
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138 | seed node that blocks for long periods will slow down everybody else. |
118 | |
139 | |
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140 | For small networks, it's best if every node uses the same set of seed |
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141 | nodes. For large networks, it can be useful to specify "regional" seed |
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142 | nodes for most nodes in an area, and use all seed nodes as seed nodes for |
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143 | each other. What's important is that all seed nodes connections form a |
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144 | complete graph, so that the network cannot split into separate subnets |
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145 | forever. |
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146 | |
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147 | Seed nodes are represented by seed IDs. |
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148 | |
119 | =item seeds - C<host:port> |
149 | =item seed IDs - C<host:port> |
120 | |
150 | |
121 | Seeds are transport endpoint(s) (usually a hostname/IP address and a |
151 | Seed IDs are transport endpoint(s) (usually a hostname/IP address and a |
122 | TCP port) of nodes thta should be used as seed nodes. |
152 | TCP port) of nodes that should be used as seed nodes. |
123 | |
153 | |
124 | The nodes listening on those endpoints are expected to be long-running, |
154 | =item global nodes |
125 | and at least one of those should always be available. When nodes run out |
155 | |
126 | of connections (e.g. due to a network error), they try to re-establish |
156 | An AEMP network needs a discovery service - nodes need to know how to |
127 | connections to some seednodes again to join the network. |
157 | connect to other nodes they only know by name. In addition, AEMP offers a |
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158 | distributed "group database", which maps group names to a list of strings |
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159 | - for example, to register worker ports. |
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160 | |
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161 | A network needs at least one global node to work, and allows every node to |
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162 | be a global node. |
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163 | |
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164 | Any node that loads the L<AnyEvent::MP::Global> module becomes a global |
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165 | node and tries to keep connections to all other nodes. So while it can |
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166 | make sense to make every node "global" in small networks, it usually makes |
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167 | sense to only make seed nodes into global nodes in large networks (nodes |
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168 | keep connections to seed nodes and global nodes, so makign them the same |
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169 | reduces overhead). |
128 | |
170 | |
129 | =back |
171 | =back |
130 | |
172 | |
131 | =head1 VARIABLES/FUNCTIONS |
173 | =head1 VARIABLES/FUNCTIONS |
132 | |
174 | |
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134 | |
176 | |
135 | =cut |
177 | =cut |
136 | |
178 | |
137 | package AnyEvent::MP; |
179 | package AnyEvent::MP; |
138 | |
180 | |
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181 | use AnyEvent::MP::Config (); |
139 | use AnyEvent::MP::Kernel; |
182 | use AnyEvent::MP::Kernel; |
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183 | use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID); |
140 | |
184 | |
141 | use common::sense; |
185 | use common::sense; |
142 | |
186 | |
143 | use Carp (); |
187 | use Carp (); |
144 | |
188 | |
145 | use AE (); |
189 | use AE (); |
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190 | use Guard (); |
146 | |
191 | |
147 | use base "Exporter"; |
192 | use base "Exporter"; |
148 | |
193 | |
149 | our $VERSION = $AnyEvent::MP::Kernel::VERSION; |
194 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
150 | |
195 | |
151 | our @EXPORT = qw( |
196 | our @EXPORT = qw( |
152 | NODE $NODE *SELF node_of after |
197 | NODE $NODE *SELF node_of after |
153 | configure |
198 | configure |
154 | snd rcv mon mon_guard kil reg psub spawn |
199 | snd rcv mon mon_guard kil psub peval spawn cal |
155 | port |
200 | port |
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201 | db_set db_del db_reg |
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202 | db_mon db_family db_keys db_values |
156 | ); |
203 | ); |
157 | |
204 | |
158 | our $SELF; |
205 | our $SELF; |
159 | |
206 | |
160 | sub _self_die() { |
207 | sub _self_die() { |
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183 | some other nodes in the network to discover other nodes. |
230 | some other nodes in the network to discover other nodes. |
184 | |
231 | |
185 | This function configures a node - it must be called exactly once (or |
232 | This function configures a node - it must be called exactly once (or |
186 | never) before calling other AnyEvent::MP functions. |
233 | never) before calling other AnyEvent::MP functions. |
187 | |
234 | |
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235 | The key/value pairs are basically the same ones as documented for the |
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236 | F<aemp> command line utility (sans the set/del prefix), with these additions: |
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237 | |
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238 | =over 4 |
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239 | |
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240 | =item norc => $boolean (default false) |
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241 | |
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242 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
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243 | be consulted - all configuraiton options must be specified in the |
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244 | C<configure> call. |
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245 | |
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246 | =item force => $boolean (default false) |
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247 | |
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248 | IF true, then the values specified in the C<configure> will take |
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249 | precedence over any values configured via the rc file. The default is for |
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250 | the rc file to override any options specified in the program. |
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251 | |
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252 | =item secure => $pass->($nodeid) |
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253 | |
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254 | In addition to specifying a boolean, you can specify a code reference that |
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255 | is called for every remote execution attempt - the execution request is |
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256 | granted iff the callback returns a true value. |
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257 | |
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258 | See F<semp setsecure> for more info. |
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259 | |
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260 | =back |
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261 | |
188 | =over 4 |
262 | =over 4 |
189 | |
263 | |
190 | =item step 1, gathering configuration from profiles |
264 | =item step 1, gathering configuration from profiles |
191 | |
265 | |
192 | The function first looks up a profile in the aemp configuration (see the |
266 | The function first looks up a profile in the aemp configuration (see the |
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205 | That means that the values specified in the profile have highest priority |
279 | That means that the values specified in the profile have highest priority |
206 | and the values specified directly via C<configure> have lowest priority, |
280 | and the values specified directly via C<configure> have lowest priority, |
207 | and can only be used to specify defaults. |
281 | and can only be used to specify defaults. |
208 | |
282 | |
209 | If the profile specifies a node ID, then this will become the node ID of |
283 | If the profile specifies a node ID, then this will become the node ID of |
210 | this process. If not, then the profile name will be used as node ID. The |
284 | this process. If not, then the profile name will be used as node ID, with |
211 | special node ID of C<anon/> will be replaced by a random node ID. |
285 | a unique randoms tring (C</%u>) appended. |
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286 | |
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287 | The node ID can contain some C<%> sequences that are expanded: C<%n> |
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288 | is expanded to the local nodename, C<%u> is replaced by a random |
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289 | strign to make the node unique. For example, the F<aemp> commandline |
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290 | utility uses C<aemp/%n/%u> as nodename, which might expand to |
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291 | C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>. |
212 | |
292 | |
213 | =item step 2, bind listener sockets |
293 | =item step 2, bind listener sockets |
214 | |
294 | |
215 | The next step is to look up the binds in the profile, followed by binding |
295 | The next step is to look up the binds in the profile, followed by binding |
216 | aemp protocol listeners on all binds specified (it is possible and valid |
296 | aemp protocol listeners on all binds specified (it is possible and valid |
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222 | used, meaning the node will bind on a dynamically-assigned port on every |
302 | used, meaning the node will bind on a dynamically-assigned port on every |
223 | local IP address it finds. |
303 | local IP address it finds. |
224 | |
304 | |
225 | =item step 3, connect to seed nodes |
305 | =item step 3, connect to seed nodes |
226 | |
306 | |
227 | As the last step, the seeds list from the profile is passed to the |
307 | As the last step, the seed ID list from the profile is passed to the |
228 | L<AnyEvent::MP::Global> module, which will then use it to keep |
308 | L<AnyEvent::MP::Global> module, which will then use it to keep |
229 | connectivity with at least one node at any point in time. |
309 | connectivity with at least one node at any point in time. |
230 | |
310 | |
231 | =back |
311 | =back |
232 | |
312 | |
233 | Example: become a distributed node using the locla node name as profile. |
313 | Example: become a distributed node using the local node name as profile. |
234 | This should be the most common form of invocation for "daemon"-type nodes. |
314 | This should be the most common form of invocation for "daemon"-type nodes. |
235 | |
315 | |
236 | configure |
316 | configure |
237 | |
317 | |
238 | Example: become an anonymous node. This form is often used for commandline |
318 | Example: become a semi-anonymous node. This form is often used for |
239 | clients. |
319 | commandline clients. |
240 | |
320 | |
241 | configure nodeid => "anon/"; |
321 | configure nodeid => "myscript/%n/%u"; |
242 | |
322 | |
243 | Example: configure a node using a profile called seed, which si suitable |
323 | Example: configure a node using a profile called seed, which is suitable |
244 | for a seed node as it binds on all local addresses on a fixed port (4040, |
324 | for a seed node as it binds on all local addresses on a fixed port (4040, |
245 | customary for aemp). |
325 | customary for aemp). |
246 | |
326 | |
247 | # use the aemp commandline utility |
327 | # use the aemp commandline utility |
248 | # aemp profile seed nodeid anon/ binds '*:4040' |
328 | # aemp profile seed binds '*:4040' |
249 | |
329 | |
250 | # then use it |
330 | # then use it |
251 | configure profile => "seed"; |
331 | configure profile => "seed"; |
252 | |
332 | |
253 | # or simply use aemp from the shell again: |
333 | # or simply use aemp from the shell again: |
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323 | sub _kilme { |
403 | sub _kilme { |
324 | die "received message on port without callback"; |
404 | die "received message on port without callback"; |
325 | } |
405 | } |
326 | |
406 | |
327 | sub port(;&) { |
407 | sub port(;&) { |
328 | my $id = "$UNIQ." . $ID++; |
408 | my $id = $UNIQ . ++$ID; |
329 | my $port = "$NODE#$id"; |
409 | my $port = "$NODE#$id"; |
330 | |
410 | |
331 | rcv $port, shift || \&_kilme; |
411 | rcv $port, shift || \&_kilme; |
332 | |
412 | |
333 | $port |
413 | $port |
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372 | msg1 => sub { ... }, |
452 | msg1 => sub { ... }, |
373 | ... |
453 | ... |
374 | ; |
454 | ; |
375 | |
455 | |
376 | Example: temporarily register a rcv callback for a tag matching some port |
456 | Example: temporarily register a rcv callback for a tag matching some port |
377 | (e.g. for a rpc reply) and unregister it after a message was received. |
457 | (e.g. for an rpc reply) and unregister it after a message was received. |
378 | |
458 | |
379 | rcv $port, $otherport => sub { |
459 | rcv $port, $otherport => sub { |
380 | my @reply = @_; |
460 | my @reply = @_; |
381 | |
461 | |
382 | rcv $SELF, $otherport; |
462 | rcv $SELF, $otherport; |
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395 | if (ref $_[0]) { |
475 | if (ref $_[0]) { |
396 | if (my $self = $PORT_DATA{$portid}) { |
476 | if (my $self = $PORT_DATA{$portid}) { |
397 | "AnyEvent::MP::Port" eq ref $self |
477 | "AnyEvent::MP::Port" eq ref $self |
398 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
478 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
399 | |
479 | |
400 | $self->[2] = shift; |
480 | $self->[0] = shift; |
401 | } else { |
481 | } else { |
402 | my $cb = shift; |
482 | my $cb = shift; |
403 | $PORT{$portid} = sub { |
483 | $PORT{$portid} = sub { |
404 | local $SELF = $port; |
484 | local $SELF = $port; |
405 | eval { &$cb }; _self_die if $@; |
485 | eval { &$cb }; _self_die if $@; |
406 | }; |
486 | }; |
407 | } |
487 | } |
408 | } elsif (defined $_[0]) { |
488 | } elsif (defined $_[0]) { |
409 | my $self = $PORT_DATA{$portid} ||= do { |
489 | my $self = $PORT_DATA{$portid} ||= do { |
410 | my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
490 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
411 | |
491 | |
412 | $PORT{$portid} = sub { |
492 | $PORT{$portid} = sub { |
413 | local $SELF = $port; |
493 | local $SELF = $port; |
414 | |
494 | |
415 | if (my $cb = $self->[1]{$_[0]}) { |
495 | if (my $cb = $self->[1]{$_[0]}) { |
… | |
… | |
437 | } |
517 | } |
438 | |
518 | |
439 | $port |
519 | $port |
440 | } |
520 | } |
441 | |
521 | |
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522 | =item peval $port, $coderef[, @args] |
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523 | |
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524 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
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525 | when the code throews an exception the C<$port> will be killed. |
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526 | |
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527 | Any remaining args will be passed to the callback. Any return values will |
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528 | be returned to the caller. |
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529 | |
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530 | This is useful when you temporarily want to execute code in the context of |
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531 | a port. |
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532 | |
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533 | Example: create a port and run some initialisation code in it's context. |
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534 | |
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535 | my $port = port { ... }; |
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536 | |
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537 | peval $port, sub { |
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538 | init |
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539 | or die "unable to init"; |
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540 | }; |
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541 | |
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542 | =cut |
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543 | |
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544 | sub peval($$) { |
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545 | local $SELF = shift; |
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546 | my $cb = shift; |
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547 | |
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548 | if (wantarray) { |
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549 | my @res = eval { &$cb }; |
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550 | _self_die if $@; |
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551 | @res |
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552 | } else { |
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553 | my $res = eval { &$cb }; |
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554 | _self_die if $@; |
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555 | $res |
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556 | } |
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557 | } |
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558 | |
442 | =item $closure = psub { BLOCK } |
559 | =item $closure = psub { BLOCK } |
443 | |
560 | |
444 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
561 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
445 | closure is executed, sets up the environment in the same way as in C<rcv> |
562 | closure is executed, sets up the environment in the same way as in C<rcv> |
446 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
563 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
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564 | |
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565 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
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566 | BLOCK }, @_ } >>. |
447 | |
567 | |
448 | This is useful when you register callbacks from C<rcv> callbacks: |
568 | This is useful when you register callbacks from C<rcv> callbacks: |
449 | |
569 | |
450 | rcv delayed_reply => sub { |
570 | rcv delayed_reply => sub { |
451 | my ($delay, @reply) = @_; |
571 | my ($delay, @reply) = @_; |
… | |
… | |
524 | delivered again. |
644 | delivered again. |
525 | |
645 | |
526 | Inter-host-connection timeouts and monitoring depend on the transport |
646 | Inter-host-connection timeouts and monitoring depend on the transport |
527 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
647 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
528 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
648 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
529 | non-idle connection, and usually around two hours for idle conenctions). |
649 | non-idle connection, and usually around two hours for idle connections). |
530 | |
650 | |
531 | This means that monitoring is good for program errors and cleaning up |
651 | This means that monitoring is good for program errors and cleaning up |
532 | stuff eventually, but they are no replacement for a timeout when you need |
652 | stuff eventually, but they are no replacement for a timeout when you need |
533 | to ensure some maximum latency. |
653 | to ensure some maximum latency. |
534 | |
654 | |
… | |
… | |
566 | } |
686 | } |
567 | |
687 | |
568 | $node->monitor ($port, $cb); |
688 | $node->monitor ($port, $cb); |
569 | |
689 | |
570 | defined wantarray |
690 | defined wantarray |
571 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
691 | and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) }) |
572 | } |
692 | } |
573 | |
693 | |
574 | =item $guard = mon_guard $port, $ref, $ref... |
694 | =item $guard = mon_guard $port, $ref, $ref... |
575 | |
695 | |
576 | Monitors the given C<$port> and keeps the passed references. When the port |
696 | Monitors the given C<$port> and keeps the passed references. When the port |
… | |
… | |
599 | |
719 | |
600 | =item kil $port[, @reason] |
720 | =item kil $port[, @reason] |
601 | |
721 | |
602 | Kill the specified port with the given C<@reason>. |
722 | Kill the specified port with the given C<@reason>. |
603 | |
723 | |
604 | If no C<@reason> is specified, then the port is killed "normally" (ports |
724 | If no C<@reason> is specified, then the port is killed "normally" - |
605 | monitoring other ports will not necessarily die because a port dies |
725 | monitor callback will be invoked, but the kil will not cause linked ports |
606 | "normally"). |
726 | (C<mon $mport, $lport> form) to get killed. |
607 | |
727 | |
608 | Otherwise, linked ports get killed with the same reason (second form of |
728 | If a C<@reason> is specified, then linked ports (C<mon $mport, $lport> |
609 | C<mon>, see above). |
729 | form) get killed with the same reason. |
610 | |
730 | |
611 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
731 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
612 | will be reported as reason C<< die => $@ >>. |
732 | will be reported as reason C<< die => $@ >>. |
613 | |
733 | |
614 | Transport/communication errors are reported as C<< transport_error => |
734 | Transport/communication errors are reported as C<< transport_error => |
… | |
… | |
680 | } |
800 | } |
681 | |
801 | |
682 | sub spawn(@) { |
802 | sub spawn(@) { |
683 | my ($nodeid, undef) = split /#/, shift, 2; |
803 | my ($nodeid, undef) = split /#/, shift, 2; |
684 | |
804 | |
685 | my $id = "$RUNIQ." . $ID++; |
805 | my $id = $RUNIQ . ++$ID; |
686 | |
806 | |
687 | $_[0] =~ /::/ |
807 | $_[0] =~ /::/ |
688 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
808 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
689 | |
809 | |
690 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
810 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
691 | |
811 | |
692 | "$nodeid#$id" |
812 | "$nodeid#$id" |
693 | } |
813 | } |
|
|
814 | |
694 | |
815 | |
695 | =item after $timeout, @msg |
816 | =item after $timeout, @msg |
696 | |
817 | |
697 | =item after $timeout, $callback |
818 | =item after $timeout, $callback |
698 | |
819 | |
… | |
… | |
714 | ? $action[0]() |
835 | ? $action[0]() |
715 | : snd @action; |
836 | : snd @action; |
716 | }; |
837 | }; |
717 | } |
838 | } |
718 | |
839 | |
|
|
840 | =item cal $port, @msg, $callback[, $timeout] |
|
|
841 | |
|
|
842 | A simple form of RPC - sends a message to the given C<$port> with the |
|
|
843 | given contents (C<@msg>), but adds a reply port to the message. |
|
|
844 | |
|
|
845 | The reply port is created temporarily just for the purpose of receiving |
|
|
846 | the reply, and will be C<kil>ed when no longer needed. |
|
|
847 | |
|
|
848 | A reply message sent to the port is passed to the C<$callback> as-is. |
|
|
849 | |
|
|
850 | If an optional time-out (in seconds) is given and it is not C<undef>, |
|
|
851 | then the callback will be called without any arguments after the time-out |
|
|
852 | elapsed and the port is C<kil>ed. |
|
|
853 | |
|
|
854 | If no time-out is given (or it is C<undef>), then the local port will |
|
|
855 | monitor the remote port instead, so it eventually gets cleaned-up. |
|
|
856 | |
|
|
857 | Currently this function returns the temporary port, but this "feature" |
|
|
858 | might go in future versions unless you can make a convincing case that |
|
|
859 | this is indeed useful for something. |
|
|
860 | |
|
|
861 | =cut |
|
|
862 | |
|
|
863 | sub cal(@) { |
|
|
864 | my $timeout = ref $_[-1] ? undef : pop; |
|
|
865 | my $cb = pop; |
|
|
866 | |
|
|
867 | my $port = port { |
|
|
868 | undef $timeout; |
|
|
869 | kil $SELF; |
|
|
870 | &$cb; |
|
|
871 | }; |
|
|
872 | |
|
|
873 | if (defined $timeout) { |
|
|
874 | $timeout = AE::timer $timeout, 0, sub { |
|
|
875 | undef $timeout; |
|
|
876 | kil $port; |
|
|
877 | $cb->(); |
|
|
878 | }; |
|
|
879 | } else { |
|
|
880 | mon $_[0], sub { |
|
|
881 | kil $port; |
|
|
882 | $cb->(); |
|
|
883 | }; |
|
|
884 | } |
|
|
885 | |
|
|
886 | push @_, $port; |
|
|
887 | &snd; |
|
|
888 | |
|
|
889 | $port |
|
|
890 | } |
|
|
891 | |
|
|
892 | =back |
|
|
893 | |
|
|
894 | =head1 DISTRIBUTED DATABASE |
|
|
895 | |
|
|
896 | AnyEvent::MP comes with a simple distributed database. The database will |
|
|
897 | be mirrored asynchronously at all global nodes. Other nodes bind to one of |
|
|
898 | the global nodes for their needs. |
|
|
899 | |
|
|
900 | The database consists of a two-level hash - a hash contains a hash which |
|
|
901 | contains values. |
|
|
902 | |
|
|
903 | The top level hash key is called "family", and the second-level hash key |
|
|
904 | is called "subkey" or simply "key". |
|
|
905 | |
|
|
906 | The family must be alphanumeric, i.e. start with a letter and consist |
|
|
907 | of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>, |
|
|
908 | pretty much like Perl module names. |
|
|
909 | |
|
|
910 | As the family namespace is global, it is recommended to prefix family names |
|
|
911 | with the name of the application or module using it. |
|
|
912 | |
|
|
913 | The subkeys must be non-empty strings, with no further restrictions. |
|
|
914 | |
|
|
915 | The values should preferably be strings, but other perl scalars should |
|
|
916 | work as well (such as undef, arrays and hashes). |
|
|
917 | |
|
|
918 | Every database entry is owned by one node - adding the same family/subkey |
|
|
919 | combination on multiple nodes will not cause discomfort for AnyEvent::MP, |
|
|
920 | but the result might be nondeterministic, i.e. the key might have |
|
|
921 | different values on different nodes. |
|
|
922 | |
|
|
923 | Different subkeys in the same family can be owned by different nodes |
|
|
924 | without problems, and in fact, this is the common method to create worker |
|
|
925 | pools. For example, a worker port for image scaling might do this: |
|
|
926 | |
|
|
927 | db_set my_image_scalers => $port; |
|
|
928 | |
|
|
929 | And clients looking for an image scaler will want to get the |
|
|
930 | C<my_image_scalers> keys: |
|
|
931 | |
|
|
932 | db_keys "my_image_scalers" => 60 => sub { |
|
|
933 | #d##TODO# |
|
|
934 | |
|
|
935 | =over |
|
|
936 | |
|
|
937 | =item db_set $family => $subkey [=> $value] |
|
|
938 | |
|
|
939 | Sets (or replaces) a key to the database - if C<$value> is omitted, |
|
|
940 | C<undef> is used instead. |
|
|
941 | |
|
|
942 | =item db_del $family => $subkey |
|
|
943 | |
|
|
944 | Deletes a key from the database. |
|
|
945 | |
|
|
946 | =item $guard = db_reg $family => $subkey [=> $value] |
|
|
947 | |
|
|
948 | Sets the key on the database and returns a guard. When the guard is |
|
|
949 | destroyed, the key is deleted from the database. If C<$value> is missing, |
|
|
950 | then C<undef> is used. |
|
|
951 | |
|
|
952 | =item $guard = db_mon $family => $cb->($familyhash, \@subkeys...) |
|
|
953 | |
|
|
954 | Creates a monitor on the given database family. Each time a key is set or |
|
|
955 | or is deleted the callback is called with a hash containing the database |
|
|
956 | family and an arrayref with subkeys that have changed. |
|
|
957 | |
|
|
958 | Specifically, if one of the passed subkeys exists in the $familyhash, then |
|
|
959 | it is currently set to the value in the $familyhash. Otherwise, it has |
|
|
960 | been deleted. |
|
|
961 | |
|
|
962 | The first call will be with the current contents of the family and all |
|
|
963 | keys, as if they were just added. |
|
|
964 | |
|
|
965 | It is possible that the callback is called with a change event even though |
|
|
966 | the subkey is already present and the value has not changed. |
|
|
967 | |
|
|
968 | The monitoring stops when the guard object is destroyed. |
|
|
969 | |
|
|
970 | Example: on every change to the family "mygroup", print out all keys. |
|
|
971 | |
|
|
972 | my $guard = db_mon mygroup => sub { |
|
|
973 | my ($family, $keys) = @_; |
|
|
974 | print "mygroup members: ", (join " ", keys %$family), "\n"; |
|
|
975 | }; |
|
|
976 | |
|
|
977 | Exmaple: wait until the family "My::Module::workers" is non-empty. |
|
|
978 | |
|
|
979 | my $guard; $guard = db_mon My::Module::workers => sub { |
|
|
980 | my ($family, $keys) = @_; |
|
|
981 | return unless %$family; |
|
|
982 | undef $guard; |
|
|
983 | print "My::Module::workers now nonempty\n"; |
|
|
984 | }; |
|
|
985 | |
|
|
986 | Example: print all changes to the family "AnyRvent::Fantasy::Module". |
|
|
987 | |
|
|
988 | my $guard = db_mon AnyRvent::Fantasy::Module => sub { |
|
|
989 | my ($family, $keys) = @_; |
|
|
990 | |
|
|
991 | for (@$keys) { |
|
|
992 | print "$_: ", |
|
|
993 | (exists $family->{$_} |
|
|
994 | ? $family->{$_} |
|
|
995 | : "(deleted)"), |
|
|
996 | "\n"; |
|
|
997 | } |
|
|
998 | }; |
|
|
999 | |
|
|
1000 | =cut |
|
|
1001 | |
719 | =back |
1002 | =back |
720 | |
1003 | |
721 | =head1 AnyEvent::MP vs. Distributed Erlang |
1004 | =head1 AnyEvent::MP vs. Distributed Erlang |
722 | |
1005 | |
723 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
1006 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
724 | == aemp node, Erlang process == aemp port), so many of the documents and |
1007 | == aemp node, Erlang process == aemp port), so many of the documents and |
725 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
1008 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
726 | sample: |
1009 | sample: |
727 | |
1010 | |
728 | http://www.Erlang.se/doc/programming_rules.shtml |
1011 | http://www.erlang.se/doc/programming_rules.shtml |
729 | http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
1012 | http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
730 | http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6 |
1013 | http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6 |
731 | http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
1014 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
732 | |
1015 | |
733 | Despite the similarities, there are also some important differences: |
1016 | Despite the similarities, there are also some important differences: |
734 | |
1017 | |
735 | =over 4 |
1018 | =over 4 |
736 | |
1019 | |
737 | =item * Node IDs are arbitrary strings in AEMP. |
1020 | =item * Node IDs are arbitrary strings in AEMP. |
738 | |
1021 | |
739 | Erlang relies on special naming and DNS to work everywhere in the same |
1022 | Erlang relies on special naming and DNS to work everywhere in the same |
740 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
1023 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
741 | configuration or DNS), but will otherwise discover other odes itself. |
1024 | configuration or DNS), and possibly the addresses of some seed nodes, but |
|
|
1025 | will otherwise discover other nodes (and their IDs) itself. |
742 | |
1026 | |
743 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
1027 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
744 | uses "local ports are like remote ports". |
1028 | uses "local ports are like remote ports". |
745 | |
1029 | |
746 | The failure modes for local ports are quite different (runtime errors |
1030 | The failure modes for local ports are quite different (runtime errors |
… | |
… | |
755 | ports being the special case/exception, where transport errors cannot |
1039 | ports being the special case/exception, where transport errors cannot |
756 | occur. |
1040 | occur. |
757 | |
1041 | |
758 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
1042 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
759 | |
1043 | |
760 | Erlang uses processes that selectively receive messages, and therefore |
1044 | Erlang uses processes that selectively receive messages out of order, and |
761 | needs a queue. AEMP is event based, queuing messages would serve no |
1045 | therefore needs a queue. AEMP is event based, queuing messages would serve |
762 | useful purpose. For the same reason the pattern-matching abilities of |
1046 | no useful purpose. For the same reason the pattern-matching abilities |
763 | AnyEvent::MP are more limited, as there is little need to be able to |
1047 | of AnyEvent::MP are more limited, as there is little need to be able to |
764 | filter messages without dequeuing them. |
1048 | filter messages without dequeuing them. |
765 | |
1049 | |
766 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
1050 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
|
|
1051 | being event-based, while Erlang is process-based. |
|
|
1052 | |
|
|
1053 | You cna have a look at L<Coro::MP> for a more Erlang-like process model on |
|
|
1054 | top of AEMP and Coro threads. |
767 | |
1055 | |
768 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
1056 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
769 | |
1057 | |
770 | Sending messages in Erlang is synchronous and blocks the process (and |
1058 | Sending messages in Erlang is synchronous and blocks the process until |
|
|
1059 | a conenction has been established and the message sent (and so does not |
771 | so does not need a queue that can overflow). AEMP sends are immediate, |
1060 | need a queue that can overflow). AEMP sends return immediately, connection |
772 | connection establishment is handled in the background. |
1061 | establishment is handled in the background. |
773 | |
1062 | |
774 | =item * Erlang suffers from silent message loss, AEMP does not. |
1063 | =item * Erlang suffers from silent message loss, AEMP does not. |
775 | |
1064 | |
776 | Erlang makes few guarantees on messages delivery - messages can get lost |
1065 | Erlang implements few guarantees on messages delivery - messages can get |
777 | without any of the processes realising it (i.e. you send messages a, b, |
1066 | lost without any of the processes realising it (i.e. you send messages a, |
778 | and c, and the other side only receives messages a and c). |
1067 | b, and c, and the other side only receives messages a and c). |
779 | |
1068 | |
780 | AEMP guarantees correct ordering, and the guarantee that after one message |
1069 | AEMP guarantees (modulo hardware errors) correct ordering, and the |
781 | is lost, all following ones sent to the same port are lost as well, until |
1070 | guarantee that after one message is lost, all following ones sent to the |
782 | monitoring raises an error, so there are no silent "holes" in the message |
1071 | same port are lost as well, until monitoring raises an error, so there are |
783 | sequence. |
1072 | no silent "holes" in the message sequence. |
|
|
1073 | |
|
|
1074 | If you want your software to be very reliable, you have to cope with |
|
|
1075 | corrupted and even out-of-order messages in both Erlang and AEMP. AEMP |
|
|
1076 | simply tries to work better in common error cases, such as when a network |
|
|
1077 | link goes down. |
784 | |
1078 | |
785 | =item * Erlang can send messages to the wrong port, AEMP does not. |
1079 | =item * Erlang can send messages to the wrong port, AEMP does not. |
786 | |
1080 | |
787 | In Erlang it is quite likely that a node that restarts reuses a process ID |
1081 | In Erlang it is quite likely that a node that restarts reuses an Erlang |
788 | known to other nodes for a completely different process, causing messages |
1082 | process ID known to other nodes for a completely different process, |
789 | destined for that process to end up in an unrelated process. |
1083 | causing messages destined for that process to end up in an unrelated |
|
|
1084 | process. |
790 | |
1085 | |
791 | AEMP never reuses port IDs, so old messages or old port IDs floating |
1086 | AEMP does not reuse port IDs, so old messages or old port IDs floating |
792 | around in the network will not be sent to an unrelated port. |
1087 | around in the network will not be sent to an unrelated port. |
793 | |
1088 | |
794 | =item * Erlang uses unprotected connections, AEMP uses secure |
1089 | =item * Erlang uses unprotected connections, AEMP uses secure |
795 | authentication and can use TLS. |
1090 | authentication and can use TLS. |
796 | |
1091 | |
… | |
… | |
799 | |
1094 | |
800 | =item * The AEMP protocol is optimised for both text-based and binary |
1095 | =item * The AEMP protocol is optimised for both text-based and binary |
801 | communications. |
1096 | communications. |
802 | |
1097 | |
803 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
1098 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
804 | language independent text-only protocols (good for debugging) and binary, |
1099 | language independent text-only protocols (good for debugging), and binary, |
805 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
1100 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
806 | used, the protocol is actually completely text-based. |
1101 | used, the protocol is actually completely text-based. |
807 | |
1102 | |
808 | It has also been carefully designed to be implementable in other languages |
1103 | It has also been carefully designed to be implementable in other languages |
809 | with a minimum of work while gracefully degrading functionality to make the |
1104 | with a minimum of work while gracefully degrading functionality to make the |
810 | protocol simple. |
1105 | protocol simple. |
811 | |
1106 | |
812 | =item * AEMP has more flexible monitoring options than Erlang. |
1107 | =item * AEMP has more flexible monitoring options than Erlang. |
813 | |
1108 | |
814 | In Erlang, you can chose to receive I<all> exit signals as messages |
1109 | In Erlang, you can chose to receive I<all> exit signals as messages or |
815 | or I<none>, there is no in-between, so monitoring single processes is |
1110 | I<none>, there is no in-between, so monitoring single Erlang processes is |
816 | difficult to implement. Monitoring in AEMP is more flexible than in |
1111 | difficult to implement. |
817 | Erlang, as one can choose between automatic kill, exit message or callback |
1112 | |
818 | on a per-process basis. |
1113 | Monitoring in AEMP is more flexible than in Erlang, as one can choose |
|
|
1114 | between automatic kill, exit message or callback on a per-port basis. |
819 | |
1115 | |
820 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
1116 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
821 | |
1117 | |
822 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
1118 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
823 | same way as linking is (except linking is unreliable in Erlang). |
1119 | same way as linking is (except linking is unreliable in Erlang). |
… | |
… | |
845 | overhead, as well as having to keep a proxy object everywhere. |
1141 | overhead, as well as having to keep a proxy object everywhere. |
846 | |
1142 | |
847 | Strings can easily be printed, easily serialised etc. and need no special |
1143 | Strings can easily be printed, easily serialised etc. and need no special |
848 | procedures to be "valid". |
1144 | procedures to be "valid". |
849 | |
1145 | |
850 | And as a result, a miniport consists of a single closure stored in a |
1146 | And as a result, a port with just a default receiver consists of a single |
851 | global hash - it can't become much cheaper. |
1147 | code reference stored in a global hash - it can't become much cheaper. |
852 | |
1148 | |
853 | =item Why favour JSON, why not a real serialising format such as Storable? |
1149 | =item Why favour JSON, why not a real serialising format such as Storable? |
854 | |
1150 | |
855 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
1151 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
856 | format, but currently there is no way to make a node use Storable by |
1152 | format, but currently there is no way to make a node use Storable by |
… | |
… | |
872 | |
1168 | |
873 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1169 | L<AnyEvent::MP::Intro> - a gentle introduction. |
874 | |
1170 | |
875 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
1171 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
876 | |
1172 | |
877 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
1173 | L<AnyEvent::MP::Global> - network maintenance and port groups, to find |
878 | your applications. |
1174 | your applications. |
|
|
1175 | |
|
|
1176 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
879 | |
1177 | |
880 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
1178 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
881 | all nodes. |
1179 | all nodes. |
882 | |
1180 | |
883 | L<AnyEvent>. |
1181 | L<AnyEvent>. |