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 | |
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120 | =item seed nodes |
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121 | |
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122 | When a node starts, it knows nothing about the network it is in - it |
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123 | needs to connect to at least one other node that is already in the |
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124 | network. These other nodes are called "seed nodes". |
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125 | |
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126 | Seed nodes themselves are not special - they are seed nodes only because |
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127 | some other node I<uses> them as such, but any node can be used as seed |
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128 | node for other nodes, and eahc node cna use a different set of seed nodes. |
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129 | |
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130 | In addition to discovering the network, seed nodes are also used to |
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131 | maintain the network - all nodes using the same seed node form are part of |
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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. |
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135 | |
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136 | Seed nodes are expected to be long-running, and at least one seed node |
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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. |
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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 | |
102 | =item seeds - C<host:port> |
149 | =item seed IDs - C<host:port> |
103 | |
150 | |
104 | When a node starts, it knows nothing about the network. To teach the node |
151 | Seed IDs are transport endpoint(s) (usually a hostname/IP address and a |
105 | about the network it first has to contact some other node within the |
152 | TCP port) of nodes that should be used as seed nodes. |
106 | network. This node is called a seed. |
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107 | |
153 | |
108 | Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes |
154 | =item global nodes |
109 | are expected to be long-running, and at least one of those should always |
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110 | be available. When nodes run out of connections (e.g. due to a network |
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111 | error), they try to re-establish connections to some seednodes again to |
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112 | join the network. |
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113 | |
155 | |
114 | Apart from being sued for seeding, seednodes are not special in any way - |
156 | An AEMP network needs a discovery service - nodes need to know how to |
115 | every public node can be a seednode. |
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). |
116 | |
170 | |
117 | =back |
171 | =back |
118 | |
172 | |
119 | =head1 VARIABLES/FUNCTIONS |
173 | =head1 VARIABLES/FUNCTIONS |
120 | |
174 | |
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122 | |
176 | |
123 | =cut |
177 | =cut |
124 | |
178 | |
125 | package AnyEvent::MP; |
179 | package AnyEvent::MP; |
126 | |
180 | |
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181 | use AnyEvent::MP::Config (); |
127 | 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); |
128 | |
184 | |
129 | use common::sense; |
185 | use common::sense; |
130 | |
186 | |
131 | use Carp (); |
187 | use Carp (); |
132 | |
188 | |
133 | use AE (); |
189 | use AE (); |
134 | |
190 | |
135 | use base "Exporter"; |
191 | use base "Exporter"; |
136 | |
192 | |
137 | our $VERSION = $AnyEvent::MP::Kernel::VERSION; |
193 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
138 | |
194 | |
139 | our @EXPORT = qw( |
195 | our @EXPORT = qw( |
140 | NODE $NODE *SELF node_of after |
196 | NODE $NODE *SELF node_of after |
141 | configure |
197 | configure |
142 | snd rcv mon mon_guard kil reg psub spawn |
198 | snd rcv mon mon_guard kil psub peval spawn cal |
143 | port |
199 | port |
144 | ); |
200 | ); |
145 | |
201 | |
146 | our $SELF; |
202 | our $SELF; |
147 | |
203 | |
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170 | to know is its own name, and optionally it should know the addresses of |
226 | to know is its own name, and optionally it should know the addresses of |
171 | some other nodes in the network to discover other nodes. |
227 | some other nodes in the network to discover other nodes. |
172 | |
228 | |
173 | This function configures a node - it must be called exactly once (or |
229 | This function configures a node - it must be called exactly once (or |
174 | never) before calling other AnyEvent::MP functions. |
230 | never) before calling other AnyEvent::MP functions. |
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231 | |
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232 | The key/value pairs are basically the same ones as documented for the |
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233 | F<aemp> command line utility (sans the set/del prefix), with two additions: |
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234 | |
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235 | =over 4 |
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236 | |
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237 | =item norc => $boolean (default false) |
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238 | |
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239 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
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240 | be consulted - all configuraiton options must be specified in the |
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241 | C<configure> call. |
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242 | |
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243 | =item force => $boolean (default false) |
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244 | |
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245 | IF true, then the values specified in the C<configure> will take |
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246 | precedence over any values configured via the rc file. The default is for |
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247 | the rc file to override any options specified in the program. |
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248 | |
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249 | =back |
175 | |
250 | |
176 | =over 4 |
251 | =over 4 |
177 | |
252 | |
178 | =item step 1, gathering configuration from profiles |
253 | =item step 1, gathering configuration from profiles |
179 | |
254 | |
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193 | That means that the values specified in the profile have highest priority |
268 | That means that the values specified in the profile have highest priority |
194 | and the values specified directly via C<configure> have lowest priority, |
269 | and the values specified directly via C<configure> have lowest priority, |
195 | and can only be used to specify defaults. |
270 | and can only be used to specify defaults. |
196 | |
271 | |
197 | If the profile specifies a node ID, then this will become the node ID of |
272 | If the profile specifies a node ID, then this will become the node ID of |
198 | this process. If not, then the profile name will be used as node ID. The |
273 | this process. If not, then the profile name will be used as node ID, with |
199 | special node ID of C<anon/> will be replaced by a random node ID. |
274 | a slash (C</>) attached. |
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275 | |
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276 | If the node ID (or profile name) ends with a slash (C</>), then a random |
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277 | string is appended to make it unique. |
200 | |
278 | |
201 | =item step 2, bind listener sockets |
279 | =item step 2, bind listener sockets |
202 | |
280 | |
203 | The next step is to look up the binds in the profile, followed by binding |
281 | The next step is to look up the binds in the profile, followed by binding |
204 | aemp protocol listeners on all binds specified (it is possible and valid |
282 | aemp protocol listeners on all binds specified (it is possible and valid |
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210 | used, meaning the node will bind on a dynamically-assigned port on every |
288 | used, meaning the node will bind on a dynamically-assigned port on every |
211 | local IP address it finds. |
289 | local IP address it finds. |
212 | |
290 | |
213 | =item step 3, connect to seed nodes |
291 | =item step 3, connect to seed nodes |
214 | |
292 | |
215 | As the last step, the seeds list from the profile is passed to the |
293 | As the last step, the seed ID list from the profile is passed to the |
216 | L<AnyEvent::MP::Global> module, which will then use it to keep |
294 | L<AnyEvent::MP::Global> module, which will then use it to keep |
217 | connectivity with at least one node at any point in time. |
295 | connectivity with at least one node at any point in time. |
218 | |
296 | |
219 | =back |
297 | =back |
220 | |
298 | |
221 | Example: become a distributed node using the locla node name as profile. |
299 | Example: become a distributed node using the local node name as profile. |
222 | This should be the most common form of invocation for "daemon"-type nodes. |
300 | This should be the most common form of invocation for "daemon"-type nodes. |
223 | |
301 | |
224 | configure |
302 | configure |
225 | |
303 | |
226 | Example: become an anonymous node. This form is often used for commandline |
304 | Example: become an anonymous node. This form is often used for commandline |
227 | clients. |
305 | clients. |
228 | |
306 | |
229 | configure nodeid => "anon/"; |
307 | configure nodeid => "anon/"; |
230 | |
308 | |
231 | Example: configure a node using a profile called seed, which si suitable |
309 | Example: configure a node using a profile called seed, which is suitable |
232 | for a seed node as it binds on all local addresses on a fixed port (4040, |
310 | for a seed node as it binds on all local addresses on a fixed port (4040, |
233 | customary for aemp). |
311 | customary for aemp). |
234 | |
312 | |
235 | # use the aemp commandline utility |
313 | # use the aemp commandline utility |
236 | # aemp profile seed nodeid anon/ binds '*:4040' |
314 | # aemp profile seed binds '*:4040' |
237 | |
315 | |
238 | # then use it |
316 | # then use it |
239 | configure profile => "seed"; |
317 | configure profile => "seed"; |
240 | |
318 | |
241 | # or simply use aemp from the shell again: |
319 | # or simply use aemp from the shell again: |
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311 | sub _kilme { |
389 | sub _kilme { |
312 | die "received message on port without callback"; |
390 | die "received message on port without callback"; |
313 | } |
391 | } |
314 | |
392 | |
315 | sub port(;&) { |
393 | sub port(;&) { |
316 | my $id = "$UNIQ." . $ID++; |
394 | my $id = $UNIQ . ++$ID; |
317 | my $port = "$NODE#$id"; |
395 | my $port = "$NODE#$id"; |
318 | |
396 | |
319 | rcv $port, shift || \&_kilme; |
397 | rcv $port, shift || \&_kilme; |
320 | |
398 | |
321 | $port |
399 | $port |
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360 | msg1 => sub { ... }, |
438 | msg1 => sub { ... }, |
361 | ... |
439 | ... |
362 | ; |
440 | ; |
363 | |
441 | |
364 | Example: temporarily register a rcv callback for a tag matching some port |
442 | Example: temporarily register a rcv callback for a tag matching some port |
365 | (e.g. for a rpc reply) and unregister it after a message was received. |
443 | (e.g. for an rpc reply) and unregister it after a message was received. |
366 | |
444 | |
367 | rcv $port, $otherport => sub { |
445 | rcv $port, $otherport => sub { |
368 | my @reply = @_; |
446 | my @reply = @_; |
369 | |
447 | |
370 | rcv $SELF, $otherport; |
448 | rcv $SELF, $otherport; |
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383 | if (ref $_[0]) { |
461 | if (ref $_[0]) { |
384 | if (my $self = $PORT_DATA{$portid}) { |
462 | if (my $self = $PORT_DATA{$portid}) { |
385 | "AnyEvent::MP::Port" eq ref $self |
463 | "AnyEvent::MP::Port" eq ref $self |
386 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
464 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
387 | |
465 | |
388 | $self->[2] = shift; |
466 | $self->[0] = shift; |
389 | } else { |
467 | } else { |
390 | my $cb = shift; |
468 | my $cb = shift; |
391 | $PORT{$portid} = sub { |
469 | $PORT{$portid} = sub { |
392 | local $SELF = $port; |
470 | local $SELF = $port; |
393 | eval { &$cb }; _self_die if $@; |
471 | eval { &$cb }; _self_die if $@; |
394 | }; |
472 | }; |
395 | } |
473 | } |
396 | } elsif (defined $_[0]) { |
474 | } elsif (defined $_[0]) { |
397 | my $self = $PORT_DATA{$portid} ||= do { |
475 | my $self = $PORT_DATA{$portid} ||= do { |
398 | my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
476 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
399 | |
477 | |
400 | $PORT{$portid} = sub { |
478 | $PORT{$portid} = sub { |
401 | local $SELF = $port; |
479 | local $SELF = $port; |
402 | |
480 | |
403 | if (my $cb = $self->[1]{$_[0]}) { |
481 | if (my $cb = $self->[1]{$_[0]}) { |
… | |
… | |
425 | } |
503 | } |
426 | |
504 | |
427 | $port |
505 | $port |
428 | } |
506 | } |
429 | |
507 | |
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508 | =item peval $port, $coderef[, @args] |
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509 | |
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510 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
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511 | when the code throews an exception the C<$port> will be killed. |
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512 | |
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513 | Any remaining args will be passed to the callback. Any return values will |
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514 | be returned to the caller. |
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515 | |
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516 | This is useful when you temporarily want to execute code in the context of |
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517 | a port. |
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518 | |
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519 | Example: create a port and run some initialisation code in it's context. |
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520 | |
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521 | my $port = port { ... }; |
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522 | |
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523 | peval $port, sub { |
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524 | init |
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525 | or die "unable to init"; |
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526 | }; |
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527 | |
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528 | =cut |
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529 | |
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530 | sub peval($$) { |
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531 | local $SELF = shift; |
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532 | my $cb = shift; |
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533 | |
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534 | if (wantarray) { |
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535 | my @res = eval { &$cb }; |
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536 | _self_die if $@; |
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537 | @res |
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538 | } else { |
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539 | my $res = eval { &$cb }; |
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540 | _self_die if $@; |
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541 | $res |
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542 | } |
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543 | } |
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544 | |
430 | =item $closure = psub { BLOCK } |
545 | =item $closure = psub { BLOCK } |
431 | |
546 | |
432 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
547 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
433 | closure is executed, sets up the environment in the same way as in C<rcv> |
548 | closure is executed, sets up the environment in the same way as in C<rcv> |
434 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
549 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
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550 | |
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551 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
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552 | BLOCK }, @_ } >>. |
435 | |
553 | |
436 | This is useful when you register callbacks from C<rcv> callbacks: |
554 | This is useful when you register callbacks from C<rcv> callbacks: |
437 | |
555 | |
438 | rcv delayed_reply => sub { |
556 | rcv delayed_reply => sub { |
439 | my ($delay, @reply) = @_; |
557 | my ($delay, @reply) = @_; |
… | |
… | |
512 | delivered again. |
630 | delivered again. |
513 | |
631 | |
514 | Inter-host-connection timeouts and monitoring depend on the transport |
632 | Inter-host-connection timeouts and monitoring depend on the transport |
515 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
633 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
516 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
634 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
517 | non-idle connection, and usually around two hours for idle conenctions). |
635 | non-idle connection, and usually around two hours for idle connections). |
518 | |
636 | |
519 | This means that monitoring is good for program errors and cleaning up |
637 | This means that monitoring is good for program errors and cleaning up |
520 | stuff eventually, but they are no replacement for a timeout when you need |
638 | stuff eventually, but they are no replacement for a timeout when you need |
521 | to ensure some maximum latency. |
639 | to ensure some maximum latency. |
522 | |
640 | |
… | |
… | |
554 | } |
672 | } |
555 | |
673 | |
556 | $node->monitor ($port, $cb); |
674 | $node->monitor ($port, $cb); |
557 | |
675 | |
558 | defined wantarray |
676 | defined wantarray |
559 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
677 | and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }) |
560 | } |
678 | } |
561 | |
679 | |
562 | =item $guard = mon_guard $port, $ref, $ref... |
680 | =item $guard = mon_guard $port, $ref, $ref... |
563 | |
681 | |
564 | Monitors the given C<$port> and keeps the passed references. When the port |
682 | Monitors the given C<$port> and keeps the passed references. When the port |
… | |
… | |
587 | |
705 | |
588 | =item kil $port[, @reason] |
706 | =item kil $port[, @reason] |
589 | |
707 | |
590 | Kill the specified port with the given C<@reason>. |
708 | Kill the specified port with the given C<@reason>. |
591 | |
709 | |
592 | If no C<@reason> is specified, then the port is killed "normally" (ports |
710 | If no C<@reason> is specified, then the port is killed "normally" - |
593 | monitoring other ports will not necessarily die because a port dies |
711 | monitor callback will be invoked, but the kil will not cause linked ports |
594 | "normally"). |
712 | (C<mon $mport, $lport> form) to get killed. |
595 | |
713 | |
596 | Otherwise, linked ports get killed with the same reason (second form of |
714 | If a C<@reason> is specified, then linked ports (C<mon $mport, $lport> |
597 | C<mon>, see above). |
715 | form) get killed with the same reason. |
598 | |
716 | |
599 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
717 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
600 | will be reported as reason C<< die => $@ >>. |
718 | will be reported as reason C<< die => $@ >>. |
601 | |
719 | |
602 | Transport/communication errors are reported as C<< transport_error => |
720 | Transport/communication errors are reported as C<< transport_error => |
… | |
… | |
621 | the package, then the package above the package and so on (e.g. |
739 | the package, then the package above the package and so on (e.g. |
622 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
740 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
623 | exists or it runs out of package names. |
741 | exists or it runs out of package names. |
624 | |
742 | |
625 | The init function is then called with the newly-created port as context |
743 | The init function is then called with the newly-created port as context |
626 | object (C<$SELF>) and the C<@initdata> values as arguments. |
744 | object (C<$SELF>) and the C<@initdata> values as arguments. It I<must> |
|
|
745 | call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise |
|
|
746 | the port might not get created. |
627 | |
747 | |
628 | A common idiom is to pass a local port, immediately monitor the spawned |
748 | A common idiom is to pass a local port, immediately monitor the spawned |
629 | port, and in the remote init function, immediately monitor the passed |
749 | port, and in the remote init function, immediately monitor the passed |
630 | local port. This two-way monitoring ensures that both ports get cleaned up |
750 | local port. This two-way monitoring ensures that both ports get cleaned up |
631 | when there is a problem. |
751 | when there is a problem. |
… | |
… | |
655 | |
775 | |
656 | sub _spawn { |
776 | sub _spawn { |
657 | my $port = shift; |
777 | my $port = shift; |
658 | my $init = shift; |
778 | my $init = shift; |
659 | |
779 | |
|
|
780 | # rcv will create the actual port |
660 | local $SELF = "$NODE#$port"; |
781 | local $SELF = "$NODE#$port"; |
661 | eval { |
782 | eval { |
662 | &{ load_func $init } |
783 | &{ load_func $init } |
663 | }; |
784 | }; |
664 | _self_die if $@; |
785 | _self_die if $@; |
665 | } |
786 | } |
666 | |
787 | |
667 | sub spawn(@) { |
788 | sub spawn(@) { |
668 | my ($nodeid, undef) = split /#/, shift, 2; |
789 | my ($nodeid, undef) = split /#/, shift, 2; |
669 | |
790 | |
670 | my $id = "$RUNIQ." . $ID++; |
791 | my $id = $RUNIQ . ++$ID; |
671 | |
792 | |
672 | $_[0] =~ /::/ |
793 | $_[0] =~ /::/ |
673 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
794 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
674 | |
795 | |
675 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
796 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
676 | |
797 | |
677 | "$nodeid#$id" |
798 | "$nodeid#$id" |
678 | } |
799 | } |
|
|
800 | |
679 | |
801 | |
680 | =item after $timeout, @msg |
802 | =item after $timeout, @msg |
681 | |
803 | |
682 | =item after $timeout, $callback |
804 | =item after $timeout, $callback |
683 | |
805 | |
… | |
… | |
699 | ? $action[0]() |
821 | ? $action[0]() |
700 | : snd @action; |
822 | : snd @action; |
701 | }; |
823 | }; |
702 | } |
824 | } |
703 | |
825 | |
|
|
826 | =item cal $port, @msg, $callback[, $timeout] |
|
|
827 | |
|
|
828 | A simple form of RPC - sends a message to the given C<$port> with the |
|
|
829 | given contents (C<@msg>), but adds a reply port to the message. |
|
|
830 | |
|
|
831 | The reply port is created temporarily just for the purpose of receiving |
|
|
832 | the reply, and will be C<kil>ed when no longer needed. |
|
|
833 | |
|
|
834 | A reply message sent to the port is passed to the C<$callback> as-is. |
|
|
835 | |
|
|
836 | If an optional time-out (in seconds) is given and it is not C<undef>, |
|
|
837 | then the callback will be called without any arguments after the time-out |
|
|
838 | elapsed and the port is C<kil>ed. |
|
|
839 | |
|
|
840 | If no time-out is given (or it is C<undef>), then the local port will |
|
|
841 | monitor the remote port instead, so it eventually gets cleaned-up. |
|
|
842 | |
|
|
843 | Currently this function returns the temporary port, but this "feature" |
|
|
844 | might go in future versions unless you can make a convincing case that |
|
|
845 | this is indeed useful for something. |
|
|
846 | |
|
|
847 | =cut |
|
|
848 | |
|
|
849 | sub cal(@) { |
|
|
850 | my $timeout = ref $_[-1] ? undef : pop; |
|
|
851 | my $cb = pop; |
|
|
852 | |
|
|
853 | my $port = port { |
|
|
854 | undef $timeout; |
|
|
855 | kil $SELF; |
|
|
856 | &$cb; |
|
|
857 | }; |
|
|
858 | |
|
|
859 | if (defined $timeout) { |
|
|
860 | $timeout = AE::timer $timeout, 0, sub { |
|
|
861 | undef $timeout; |
|
|
862 | kil $port; |
|
|
863 | $cb->(); |
|
|
864 | }; |
|
|
865 | } else { |
|
|
866 | mon $_[0], sub { |
|
|
867 | kil $port; |
|
|
868 | $cb->(); |
|
|
869 | }; |
|
|
870 | } |
|
|
871 | |
|
|
872 | push @_, $port; |
|
|
873 | &snd; |
|
|
874 | |
|
|
875 | $port |
|
|
876 | } |
|
|
877 | |
704 | =back |
878 | =back |
705 | |
879 | |
706 | =head1 AnyEvent::MP vs. Distributed Erlang |
880 | =head1 AnyEvent::MP vs. Distributed Erlang |
707 | |
881 | |
708 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
882 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
709 | == aemp node, Erlang process == aemp port), so many of the documents and |
883 | == aemp node, Erlang process == aemp port), so many of the documents and |
710 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
884 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
711 | sample: |
885 | sample: |
712 | |
886 | |
713 | http://www.Erlang.se/doc/programming_rules.shtml |
887 | http://www.erlang.se/doc/programming_rules.shtml |
714 | http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
888 | http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
715 | http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6 |
889 | http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6 |
716 | http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
890 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
717 | |
891 | |
718 | Despite the similarities, there are also some important differences: |
892 | Despite the similarities, there are also some important differences: |
719 | |
893 | |
720 | =over 4 |
894 | =over 4 |
721 | |
895 | |
722 | =item * Node IDs are arbitrary strings in AEMP. |
896 | =item * Node IDs are arbitrary strings in AEMP. |
723 | |
897 | |
724 | Erlang relies on special naming and DNS to work everywhere in the same |
898 | Erlang relies on special naming and DNS to work everywhere in the same |
725 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
899 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
726 | configuration or DNS), but will otherwise discover other odes itself. |
900 | configuration or DNS), and possibly the addresses of some seed nodes, but |
|
|
901 | will otherwise discover other nodes (and their IDs) itself. |
727 | |
902 | |
728 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
903 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
729 | uses "local ports are like remote ports". |
904 | uses "local ports are like remote ports". |
730 | |
905 | |
731 | The failure modes for local ports are quite different (runtime errors |
906 | The failure modes for local ports are quite different (runtime errors |
… | |
… | |
740 | ports being the special case/exception, where transport errors cannot |
915 | ports being the special case/exception, where transport errors cannot |
741 | occur. |
916 | occur. |
742 | |
917 | |
743 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
918 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
744 | |
919 | |
745 | Erlang uses processes that selectively receive messages, and therefore |
920 | Erlang uses processes that selectively receive messages out of order, and |
746 | needs a queue. AEMP is event based, queuing messages would serve no |
921 | therefore needs a queue. AEMP is event based, queuing messages would serve |
747 | useful purpose. For the same reason the pattern-matching abilities of |
922 | no useful purpose. For the same reason the pattern-matching abilities |
748 | AnyEvent::MP are more limited, as there is little need to be able to |
923 | of AnyEvent::MP are more limited, as there is little need to be able to |
749 | filter messages without dequeuing them. |
924 | filter messages without dequeuing them. |
750 | |
925 | |
751 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
926 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
|
|
927 | being event-based, while Erlang is process-based. |
|
|
928 | |
|
|
929 | You cna have a look at L<Coro::MP> for a more Erlang-like process model on |
|
|
930 | top of AEMP and Coro threads. |
752 | |
931 | |
753 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
932 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
754 | |
933 | |
755 | Sending messages in Erlang is synchronous and blocks the process (and |
934 | Sending messages in Erlang is synchronous and blocks the process until |
|
|
935 | a conenction has been established and the message sent (and so does not |
756 | so does not need a queue that can overflow). AEMP sends are immediate, |
936 | need a queue that can overflow). AEMP sends return immediately, connection |
757 | connection establishment is handled in the background. |
937 | establishment is handled in the background. |
758 | |
938 | |
759 | =item * Erlang suffers from silent message loss, AEMP does not. |
939 | =item * Erlang suffers from silent message loss, AEMP does not. |
760 | |
940 | |
761 | Erlang makes few guarantees on messages delivery - messages can get lost |
941 | Erlang implements few guarantees on messages delivery - messages can get |
762 | without any of the processes realising it (i.e. you send messages a, b, |
942 | lost without any of the processes realising it (i.e. you send messages a, |
763 | and c, and the other side only receives messages a and c). |
943 | b, and c, and the other side only receives messages a and c). |
764 | |
944 | |
765 | AEMP guarantees correct ordering, and the guarantee that after one message |
945 | AEMP guarantees (modulo hardware errors) correct ordering, and the |
766 | is lost, all following ones sent to the same port are lost as well, until |
946 | guarantee that after one message is lost, all following ones sent to the |
767 | monitoring raises an error, so there are no silent "holes" in the message |
947 | same port are lost as well, until monitoring raises an error, so there are |
768 | sequence. |
948 | no silent "holes" in the message sequence. |
|
|
949 | |
|
|
950 | If you want your software to be very reliable, you have to cope with |
|
|
951 | corrupted and even out-of-order messages in both Erlang and AEMP. AEMP |
|
|
952 | simply tries to work better in common error cases, such as when a network |
|
|
953 | link goes down. |
769 | |
954 | |
770 | =item * Erlang can send messages to the wrong port, AEMP does not. |
955 | =item * Erlang can send messages to the wrong port, AEMP does not. |
771 | |
956 | |
772 | In Erlang it is quite likely that a node that restarts reuses a process ID |
957 | In Erlang it is quite likely that a node that restarts reuses an Erlang |
773 | known to other nodes for a completely different process, causing messages |
958 | process ID known to other nodes for a completely different process, |
774 | destined for that process to end up in an unrelated process. |
959 | causing messages destined for that process to end up in an unrelated |
|
|
960 | process. |
775 | |
961 | |
776 | AEMP never reuses port IDs, so old messages or old port IDs floating |
962 | AEMP does not reuse port IDs, so old messages or old port IDs floating |
777 | around in the network will not be sent to an unrelated port. |
963 | around in the network will not be sent to an unrelated port. |
778 | |
964 | |
779 | =item * Erlang uses unprotected connections, AEMP uses secure |
965 | =item * Erlang uses unprotected connections, AEMP uses secure |
780 | authentication and can use TLS. |
966 | authentication and can use TLS. |
781 | |
967 | |
… | |
… | |
784 | |
970 | |
785 | =item * The AEMP protocol is optimised for both text-based and binary |
971 | =item * The AEMP protocol is optimised for both text-based and binary |
786 | communications. |
972 | communications. |
787 | |
973 | |
788 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
974 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
789 | language independent text-only protocols (good for debugging) and binary, |
975 | language independent text-only protocols (good for debugging), and binary, |
790 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
976 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
791 | used, the protocol is actually completely text-based. |
977 | used, the protocol is actually completely text-based. |
792 | |
978 | |
793 | It has also been carefully designed to be implementable in other languages |
979 | It has also been carefully designed to be implementable in other languages |
794 | with a minimum of work while gracefully degrading functionality to make the |
980 | with a minimum of work while gracefully degrading functionality to make the |
795 | protocol simple. |
981 | protocol simple. |
796 | |
982 | |
797 | =item * AEMP has more flexible monitoring options than Erlang. |
983 | =item * AEMP has more flexible monitoring options than Erlang. |
798 | |
984 | |
799 | In Erlang, you can chose to receive I<all> exit signals as messages |
985 | In Erlang, you can chose to receive I<all> exit signals as messages or |
800 | or I<none>, there is no in-between, so monitoring single processes is |
986 | I<none>, there is no in-between, so monitoring single Erlang processes is |
801 | difficult to implement. Monitoring in AEMP is more flexible than in |
987 | difficult to implement. |
802 | Erlang, as one can choose between automatic kill, exit message or callback |
988 | |
803 | on a per-process basis. |
989 | Monitoring in AEMP is more flexible than in Erlang, as one can choose |
|
|
990 | between automatic kill, exit message or callback on a per-port basis. |
804 | |
991 | |
805 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
992 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
806 | |
993 | |
807 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
994 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
808 | same way as linking is (except linking is unreliable in Erlang). |
995 | same way as linking is (except linking is unreliable in Erlang). |
… | |
… | |
830 | overhead, as well as having to keep a proxy object everywhere. |
1017 | overhead, as well as having to keep a proxy object everywhere. |
831 | |
1018 | |
832 | Strings can easily be printed, easily serialised etc. and need no special |
1019 | Strings can easily be printed, easily serialised etc. and need no special |
833 | procedures to be "valid". |
1020 | procedures to be "valid". |
834 | |
1021 | |
835 | And as a result, a miniport consists of a single closure stored in a |
1022 | And as a result, a port with just a default receiver consists of a single |
836 | global hash - it can't become much cheaper. |
1023 | code reference stored in a global hash - it can't become much cheaper. |
837 | |
1024 | |
838 | =item Why favour JSON, why not a real serialising format such as Storable? |
1025 | =item Why favour JSON, why not a real serialising format such as Storable? |
839 | |
1026 | |
840 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
1027 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
841 | format, but currently there is no way to make a node use Storable by |
1028 | format, but currently there is no way to make a node use Storable by |
… | |
… | |
857 | |
1044 | |
858 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1045 | L<AnyEvent::MP::Intro> - a gentle introduction. |
859 | |
1046 | |
860 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
1047 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
861 | |
1048 | |
862 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
1049 | L<AnyEvent::MP::Global> - network maintenance and port groups, to find |
863 | your applications. |
1050 | your applications. |
|
|
1051 | |
|
|
1052 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
|
|
1053 | |
|
|
1054 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
|
|
1055 | all nodes. |
864 | |
1056 | |
865 | L<AnyEvent>. |
1057 | L<AnyEvent>. |
866 | |
1058 | |
867 | =head1 AUTHOR |
1059 | =head1 AUTHOR |
868 | |
1060 | |