… | |
… | |
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 | |
35 | # destroy a prot again |
35 | # destroy a port again |
36 | kil $port; # "normal" kill |
36 | kil $port; # "normal" kill |
37 | kil $port, my_error => "everything is broken"; # error kill |
37 | kil $port, my_error => "everything is broken"; # error kill |
38 | |
38 | |
39 | # monitoring |
39 | # monitoring |
40 | mon $localport, $cb->(@msg) # callback is invoked on death |
40 | mon $port, $cb->(@msg) # callback is invoked on death |
41 | mon $localport, $otherport # kill otherport on abnormal death |
41 | mon $port, $localport # kill localport on abnormal death |
42 | mon $localport, $otherport, @msg # send message on death |
42 | mon $port, $localport, @msg # send message on death |
43 | |
43 | |
44 | # temporarily execute code in port context |
44 | # temporarily execute code in port context |
45 | peval $port, sub { die "kill the port!" }; |
45 | peval $port, sub { die "kill the port!" }; |
46 | |
46 | |
47 | # execute callbacks in $SELF port context |
47 | # execute callbacks in $SELF port context |
48 | my $timer = AE::timer 1, 0, psub { |
48 | my $timer = AE::timer 1, 0, psub { |
49 | die "kill the port, delayed"; |
49 | die "kill the port, delayed"; |
50 | }; |
50 | }; |
51 | |
51 | |
52 | =head1 CURRENT STATUS |
52 | # distributed database - modification |
|
|
53 | db_set $family => $subkey [=> $value] # add a subkey |
|
|
54 | db_del $family => $subkey... # delete one or more subkeys |
|
|
55 | db_reg $family => $port [=> $value] # register a port |
53 | |
56 | |
54 | bin/aemp - stable. |
57 | # distributed database - queries |
55 | AnyEvent::MP - stable API, should work. |
58 | db_family $family => $cb->(\%familyhash) |
56 | AnyEvent::MP::Intro - explains most concepts. |
59 | db_keys $family => $cb->(\@keys) |
57 | AnyEvent::MP::Kernel - mostly stable API. |
60 | db_values $family => $cb->(\@values) |
58 | AnyEvent::MP::Global - stable API. |
61 | |
|
|
62 | # distributed database - monitoring a family |
|
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63 | db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted) |
59 | |
64 | |
60 | =head1 DESCRIPTION |
65 | =head1 DESCRIPTION |
61 | |
66 | |
62 | This module (-family) implements a simple message passing framework. |
67 | This module (-family) implements a simple message passing framework. |
63 | |
68 | |
… | |
… | |
78 | |
83 | |
79 | Ports allow you to register C<rcv> handlers that can match all or just |
84 | Ports allow you to register C<rcv> handlers that can match all or just |
80 | some messages. Messages send to ports will not be queued, regardless of |
85 | some messages. Messages send to ports will not be queued, regardless of |
81 | anything was listening for them or not. |
86 | anything was listening for them or not. |
82 | |
87 | |
|
|
88 | Ports are represented by (printable) strings called "port IDs". |
|
|
89 | |
83 | =item port ID - C<nodeid#portname> |
90 | =item port ID - C<nodeid#portname> |
84 | |
91 | |
85 | A port ID is the concatenation of a node ID, a hash-mark (C<#>) as |
92 | A port ID is the concatenation of a node ID, a hash-mark (C<#>) |
86 | separator, and a port name (a printable string of unspecified format). |
93 | as separator, and a port name (a printable string of unspecified |
|
|
94 | format created by AnyEvent::MP). |
87 | |
95 | |
88 | =item node |
96 | =item node |
89 | |
97 | |
90 | A node is a single process containing at least one port - the node port, |
98 | A node is a single process containing at least one port - the node port, |
91 | which enables nodes to manage each other remotely, and to create new |
99 | which enables nodes to manage each other remotely, and to create new |
92 | ports. |
100 | ports. |
93 | |
101 | |
94 | Nodes are either public (have one or more listening ports) or private |
102 | Nodes are either public (have one or more listening ports) or private |
95 | (no listening ports). Private nodes cannot talk to other private nodes |
103 | (no listening ports). Private nodes cannot talk to other private nodes |
96 | currently. |
104 | currently, but all nodes can talk to public nodes. |
97 | |
105 | |
|
|
106 | Nodes is represented by (printable) strings called "node IDs". |
|
|
107 | |
98 | =item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*> |
108 | =item node ID - C<[A-Za-z0-9_\-.:]*> |
99 | |
109 | |
100 | A node ID is a string that uniquely identifies the node within a |
110 | A node ID is a string that uniquely identifies the node within a |
101 | network. Depending on the configuration used, node IDs can look like a |
111 | network. Depending on the configuration used, node IDs can look like a |
102 | hostname, a hostname and a port, or a random string. AnyEvent::MP itself |
112 | hostname, a hostname and a port, or a random string. AnyEvent::MP itself |
103 | doesn't interpret node IDs in any way. |
113 | doesn't interpret node IDs in any way except to uniquely identify a node. |
104 | |
114 | |
105 | =item binds - C<ip:port> |
115 | =item binds - C<ip:port> |
106 | |
116 | |
107 | Nodes can only talk to each other by creating some kind of connection to |
117 | Nodes can only talk to each other by creating some kind of connection to |
108 | each other. To do this, nodes should listen on one or more local transport |
118 | each other. To do this, nodes should listen on one or more local transport |
|
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119 | endpoints - binds. |
|
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120 | |
109 | endpoints - binds. Currently, only standard C<ip:port> specifications can |
121 | Currently, only standard C<ip:port> specifications can be used, which |
110 | be used, which specify TCP ports to listen on. |
122 | specify TCP ports to listen on. So a bind is basically just a tcp socket |
|
|
123 | in listening mode that accepts connections from other nodes. |
111 | |
124 | |
112 | =item seed nodes |
125 | =item seed nodes |
113 | |
126 | |
114 | When a node starts, it knows nothing about the network. To teach the node |
127 | When a node starts, it knows nothing about the network it is in - it |
115 | about the network it first has to contact some other node within the |
128 | needs to connect to at least one other node that is already in the |
116 | network. This node is called a seed. |
129 | network. These other nodes are called "seed nodes". |
117 | |
130 | |
118 | Apart from the fact that other nodes know them as seed nodes and they have |
131 | Seed nodes themselves are not special - they are seed nodes only because |
119 | to have fixed listening addresses, seed nodes are perfectly normal nodes - |
132 | some other node I<uses> them as such, but any node can be used as seed |
120 | any node can function as a seed node for others. |
133 | node for other nodes, and eahc node can use a different set of seed nodes. |
121 | |
134 | |
122 | In addition to discovering the network, seed nodes are also used to |
135 | In addition to discovering the network, seed nodes are also used to |
123 | maintain the network and to connect nodes that otherwise would have |
136 | maintain the network - all nodes using the same seed node are part of the |
124 | trouble connecting. They form the backbone of an AnyEvent::MP network. |
137 | same network. If a network is split into multiple subnets because e.g. the |
|
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138 | network link between the parts goes down, then using the same seed nodes |
|
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139 | for all nodes ensures that eventually the subnets get merged again. |
125 | |
140 | |
126 | Seed nodes are expected to be long-running, and at least one seed node |
141 | Seed nodes are expected to be long-running, and at least one seed node |
127 | should always be available. They should also be relatively responsive - a |
142 | should always be available. They should also be relatively responsive - a |
128 | seed node that blocks for long periods will slow down everybody else. |
143 | seed node that blocks for long periods will slow down everybody else. |
129 | |
144 | |
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145 | For small networks, it's best if every node uses the same set of seed |
|
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146 | nodes. For large networks, it can be useful to specify "regional" seed |
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147 | nodes for most nodes in an area, and use all seed nodes as seed nodes for |
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148 | each other. What's important is that all seed nodes connections form a |
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149 | complete graph, so that the network cannot split into separate subnets |
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150 | forever. |
|
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151 | |
|
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152 | Seed nodes are represented by seed IDs. |
|
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153 | |
130 | =item seeds - C<host:port> |
154 | =item seed IDs - C<host:port> |
131 | |
155 | |
132 | Seeds are transport endpoint(s) (usually a hostname/IP address and a |
156 | Seed IDs are transport endpoint(s) (usually a hostname/IP address and a |
133 | TCP port) of nodes that should be used as seed nodes. |
157 | TCP port) of nodes that should be used as seed nodes. |
134 | |
158 | |
135 | The nodes listening on those endpoints are expected to be long-running, |
159 | =item global nodes |
136 | and at least one of those should always be available. When nodes run out |
160 | |
137 | of connections (e.g. due to a network error), they try to re-establish |
161 | An AEMP network needs a discovery service - nodes need to know how to |
138 | connections to some seednodes again to join the network. |
162 | connect to other nodes they only know by name. In addition, AEMP offers a |
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163 | distributed "group database", which maps group names to a list of strings |
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164 | - for example, to register worker ports. |
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165 | |
|
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166 | A network needs at least one global node to work, and allows every node to |
|
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167 | be a global node. |
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168 | |
|
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169 | Any node that loads the L<AnyEvent::MP::Global> module becomes a global |
|
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170 | node and tries to keep connections to all other nodes. So while it can |
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171 | make sense to make every node "global" in small networks, it usually makes |
|
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172 | sense to only make seed nodes into global nodes in large networks (nodes |
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173 | keep connections to seed nodes and global nodes, so making them the same |
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174 | reduces overhead). |
139 | |
175 | |
140 | =back |
176 | =back |
141 | |
177 | |
142 | =head1 VARIABLES/FUNCTIONS |
178 | =head1 VARIABLES/FUNCTIONS |
143 | |
179 | |
… | |
… | |
145 | |
181 | |
146 | =cut |
182 | =cut |
147 | |
183 | |
148 | package AnyEvent::MP; |
184 | package AnyEvent::MP; |
149 | |
185 | |
|
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186 | use AnyEvent::MP::Config (); |
150 | use AnyEvent::MP::Kernel; |
187 | use AnyEvent::MP::Kernel; |
|
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188 | use AnyEvent::MP::Kernel qw( |
|
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189 | %NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID |
|
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190 | add_node load_func |
|
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191 | |
|
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192 | NODE $NODE |
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193 | configure |
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194 | node_of port_is_local |
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195 | snd kil |
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196 | db_set db_del |
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197 | db_mon db_family db_keys db_values |
|
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198 | ); |
151 | |
199 | |
152 | use common::sense; |
200 | use common::sense; |
153 | |
201 | |
154 | use Carp (); |
202 | use Carp (); |
155 | |
203 | |
156 | use AE (); |
204 | use AnyEvent (); |
|
|
205 | use Guard (); |
157 | |
206 | |
158 | use base "Exporter"; |
207 | use base "Exporter"; |
159 | |
208 | |
160 | our $VERSION = 1.23; |
209 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
161 | |
210 | |
162 | our @EXPORT = qw( |
211 | our @EXPORT = qw( |
163 | NODE $NODE *SELF node_of after |
212 | NODE $NODE |
164 | configure |
213 | configure |
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214 | node_of port_is_local |
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215 | snd kil |
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216 | db_set db_del |
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217 | db_mon db_family db_keys db_values |
|
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218 | |
|
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219 | *SELF |
|
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220 | |
165 | snd rcv mon mon_guard kil psub peval spawn cal |
221 | port rcv mon mon_guard psub peval spawn cal |
166 | port |
222 | db_set db_del db_reg |
|
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223 | db_mon db_family db_keys db_values |
|
|
224 | |
|
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225 | after |
167 | ); |
226 | ); |
168 | |
227 | |
169 | our $SELF; |
228 | our $SELF; |
170 | |
229 | |
171 | sub _self_die() { |
230 | sub _self_die() { |
… | |
… | |
182 | |
241 | |
183 | =item $nodeid = node_of $port |
242 | =item $nodeid = node_of $port |
184 | |
243 | |
185 | Extracts and returns the node ID from a port ID or a node ID. |
244 | Extracts and returns the node ID from a port ID or a node ID. |
186 | |
245 | |
|
|
246 | =item $is_local = port_is_local $port |
|
|
247 | |
|
|
248 | Returns true iff the port is a local port. |
|
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249 | |
187 | =item configure $profile, key => value... |
250 | =item configure $profile, key => value... |
188 | |
251 | |
189 | =item configure key => value... |
252 | =item configure key => value... |
190 | |
253 | |
191 | Before a node can talk to other nodes on the network (i.e. enter |
254 | Before a node can talk to other nodes on the network (i.e. enter |
… | |
… | |
193 | to know is its own name, and optionally it should know the addresses of |
256 | to know is its own name, and optionally it should know the addresses of |
194 | some other nodes in the network to discover other nodes. |
257 | some other nodes in the network to discover other nodes. |
195 | |
258 | |
196 | This function configures a node - it must be called exactly once (or |
259 | This function configures a node - it must be called exactly once (or |
197 | never) before calling other AnyEvent::MP functions. |
260 | never) before calling other AnyEvent::MP functions. |
|
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261 | |
|
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262 | The key/value pairs are basically the same ones as documented for the |
|
|
263 | F<aemp> command line utility (sans the set/del prefix), with these additions: |
|
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264 | |
|
|
265 | =over 4 |
|
|
266 | |
|
|
267 | =item norc => $boolean (default false) |
|
|
268 | |
|
|
269 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
|
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270 | be consulted - all configuration options must be specified in the |
|
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271 | C<configure> call. |
|
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272 | |
|
|
273 | =item force => $boolean (default false) |
|
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274 | |
|
|
275 | IF true, then the values specified in the C<configure> will take |
|
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276 | precedence over any values configured via the rc file. The default is for |
|
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277 | the rc file to override any options specified in the program. |
|
|
278 | |
|
|
279 | =back |
198 | |
280 | |
199 | =over 4 |
281 | =over 4 |
200 | |
282 | |
201 | =item step 1, gathering configuration from profiles |
283 | =item step 1, gathering configuration from profiles |
202 | |
284 | |
… | |
… | |
216 | That means that the values specified in the profile have highest priority |
298 | That means that the values specified in the profile have highest priority |
217 | and the values specified directly via C<configure> have lowest priority, |
299 | and the values specified directly via C<configure> have lowest priority, |
218 | and can only be used to specify defaults. |
300 | and can only be used to specify defaults. |
219 | |
301 | |
220 | If the profile specifies a node ID, then this will become the node ID of |
302 | If the profile specifies a node ID, then this will become the node ID of |
221 | this process. If not, then the profile name will be used as node ID. The |
303 | this process. If not, then the profile name will be used as node ID, with |
222 | special node ID of C<anon/> will be replaced by a random node ID. |
304 | a unique randoms tring (C</%u>) appended. |
|
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305 | |
|
|
306 | The node ID can contain some C<%> sequences that are expanded: C<%n> |
|
|
307 | is expanded to the local nodename, C<%u> is replaced by a random |
|
|
308 | strign to make the node unique. For example, the F<aemp> commandline |
|
|
309 | utility uses C<aemp/%n/%u> as nodename, which might expand to |
|
|
310 | C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>. |
223 | |
311 | |
224 | =item step 2, bind listener sockets |
312 | =item step 2, bind listener sockets |
225 | |
313 | |
226 | The next step is to look up the binds in the profile, followed by binding |
314 | The next step is to look up the binds in the profile, followed by binding |
227 | aemp protocol listeners on all binds specified (it is possible and valid |
315 | aemp protocol listeners on all binds specified (it is possible and valid |
228 | to have no binds, meaning that the node cannot be contacted form the |
316 | to have no binds, meaning that the node cannot be contacted from the |
229 | outside. This means the node cannot talk to other nodes that also have no |
317 | outside. This means the node cannot talk to other nodes that also have no |
230 | binds, but it can still talk to all "normal" nodes). |
318 | binds, but it can still talk to all "normal" nodes). |
231 | |
319 | |
232 | If the profile does not specify a binds list, then a default of C<*> is |
320 | If the profile does not specify a binds list, then a default of C<*> is |
233 | used, meaning the node will bind on a dynamically-assigned port on every |
321 | used, meaning the node will bind on a dynamically-assigned port on every |
234 | local IP address it finds. |
322 | local IP address it finds. |
235 | |
323 | |
236 | =item step 3, connect to seed nodes |
324 | =item step 3, connect to seed nodes |
237 | |
325 | |
238 | As the last step, the seeds list from the profile is passed to the |
326 | As the last step, the seed ID list from the profile is passed to the |
239 | L<AnyEvent::MP::Global> module, which will then use it to keep |
327 | L<AnyEvent::MP::Global> module, which will then use it to keep |
240 | connectivity with at least one node at any point in time. |
328 | connectivity with at least one node at any point in time. |
241 | |
329 | |
242 | =back |
330 | =back |
243 | |
331 | |
244 | Example: become a distributed node using the local node name as profile. |
332 | Example: become a distributed node using the local node name as profile. |
245 | This should be the most common form of invocation for "daemon"-type nodes. |
333 | This should be the most common form of invocation for "daemon"-type nodes. |
246 | |
334 | |
247 | configure |
335 | configure |
248 | |
336 | |
249 | Example: become an anonymous node. This form is often used for commandline |
337 | Example: become a semi-anonymous node. This form is often used for |
250 | clients. |
338 | commandline clients. |
251 | |
339 | |
252 | configure nodeid => "anon/"; |
340 | configure nodeid => "myscript/%n/%u"; |
253 | |
341 | |
254 | Example: configure a node using a profile called seed, which si suitable |
342 | Example: configure a node using a profile called seed, which is suitable |
255 | for a seed node as it binds on all local addresses on a fixed port (4040, |
343 | for a seed node as it binds on all local addresses on a fixed port (4040, |
256 | customary for aemp). |
344 | customary for aemp). |
257 | |
345 | |
258 | # use the aemp commandline utility |
346 | # use the aemp commandline utility |
259 | # aemp profile seed nodeid anon/ binds '*:4040' |
347 | # aemp profile seed binds '*:4040' |
260 | |
348 | |
261 | # then use it |
349 | # then use it |
262 | configure profile => "seed"; |
350 | configure profile => "seed"; |
263 | |
351 | |
264 | # or simply use aemp from the shell again: |
352 | # or simply use aemp from the shell again: |
… | |
… | |
329 | |
417 | |
330 | =cut |
418 | =cut |
331 | |
419 | |
332 | sub rcv($@); |
420 | sub rcv($@); |
333 | |
421 | |
334 | sub _kilme { |
422 | my $KILME = sub { |
335 | die "received message on port without callback"; |
423 | (my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g; |
336 | } |
424 | kil $SELF, unhandled_message => "no callback found for message '$tag'"; |
|
|
425 | }; |
337 | |
426 | |
338 | sub port(;&) { |
427 | sub port(;&) { |
339 | my $id = "$UNIQ." . $ID++; |
428 | my $id = $UNIQ . ++$ID; |
340 | my $port = "$NODE#$id"; |
429 | my $port = "$NODE#$id"; |
341 | |
430 | |
342 | rcv $port, shift || \&_kilme; |
431 | rcv $port, shift || $KILME; |
343 | |
432 | |
344 | $port |
433 | $port |
345 | } |
434 | } |
346 | |
435 | |
347 | =item rcv $local_port, $callback->(@msg) |
436 | =item rcv $local_port, $callback->(@msg) |
… | |
… | |
352 | |
441 | |
353 | The global C<$SELF> (exported by this module) contains C<$port> while |
442 | The global C<$SELF> (exported by this module) contains C<$port> while |
354 | executing the callback. Runtime errors during callback execution will |
443 | executing the callback. Runtime errors during callback execution will |
355 | result in the port being C<kil>ed. |
444 | result in the port being C<kil>ed. |
356 | |
445 | |
357 | The default callback received all messages not matched by a more specific |
446 | The default callback receives all messages not matched by a more specific |
358 | C<tag> match. |
447 | C<tag> match. |
359 | |
448 | |
360 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
449 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
361 | |
450 | |
362 | Register (or replace) callbacks to be called on messages starting with the |
451 | Register (or replace) callbacks to be called on messages starting with the |
… | |
… | |
397 | |
486 | |
398 | sub rcv($@) { |
487 | sub rcv($@) { |
399 | my $port = shift; |
488 | my $port = shift; |
400 | my ($nodeid, $portid) = split /#/, $port, 2; |
489 | my ($nodeid, $portid) = split /#/, $port, 2; |
401 | |
490 | |
402 | $NODE{$nodeid} == $NODE{""} |
491 | $nodeid eq $NODE |
403 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
492 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
404 | |
493 | |
405 | while (@_) { |
494 | while (@_) { |
406 | if (ref $_[0]) { |
495 | if (ref $_[0]) { |
407 | if (my $self = $PORT_DATA{$portid}) { |
496 | if (my $self = $PORT_DATA{$portid}) { |
… | |
… | |
451 | } |
540 | } |
452 | |
541 | |
453 | =item peval $port, $coderef[, @args] |
542 | =item peval $port, $coderef[, @args] |
454 | |
543 | |
455 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
544 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
456 | when the code throews an exception the C<$port> will be killed. |
545 | when the code throws an exception the C<$port> will be killed. |
457 | |
546 | |
458 | Any remaining args will be passed to the callback. Any return values will |
547 | Any remaining args will be passed to the callback. Any return values will |
459 | be returned to the caller. |
548 | be returned to the caller. |
460 | |
549 | |
461 | This is useful when you temporarily want to execute code in the context of |
550 | This is useful when you temporarily want to execute code in the context of |
… | |
… | |
492 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
581 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
493 | closure is executed, sets up the environment in the same way as in C<rcv> |
582 | closure is executed, sets up the environment in the same way as in C<rcv> |
494 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
583 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
495 | |
584 | |
496 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
585 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
497 | BLOCK } } >>. |
586 | BLOCK }, @_ } >>. |
498 | |
587 | |
499 | This is useful when you register callbacks from C<rcv> callbacks: |
588 | This is useful when you register callbacks from C<rcv> callbacks: |
500 | |
589 | |
501 | rcv delayed_reply => sub { |
590 | rcv delayed_reply => sub { |
502 | my ($delay, @reply) = @_; |
591 | my ($delay, @reply) = @_; |
… | |
… | |
526 | $res |
615 | $res |
527 | } |
616 | } |
528 | } |
617 | } |
529 | } |
618 | } |
530 | |
619 | |
|
|
620 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
621 | |
|
|
622 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
623 | |
531 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
624 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
532 | |
|
|
533 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
534 | |
|
|
535 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
536 | |
625 | |
537 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
626 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
538 | |
627 | |
539 | Monitor the given port and do something when the port is killed or |
628 | Monitor the given port and do something when the port is killed or |
540 | messages to it were lost, and optionally return a guard that can be used |
629 | messages to it were lost, and optionally return a guard that can be used |
541 | to stop monitoring again. |
630 | to stop monitoring again. |
542 | |
631 | |
|
|
632 | The first two forms distinguish between "normal" and "abnormal" kil's: |
|
|
633 | |
|
|
634 | In the first form (another port given), if the C<$port> is C<kil>'ed with |
|
|
635 | a non-empty reason, the other port (C<$rcvport>) will be kil'ed with the |
|
|
636 | same reason. That is, on "normal" kil's nothing happens, while under all |
|
|
637 | other conditions, the other port is killed with the same reason. |
|
|
638 | |
|
|
639 | The second form (kill self) is the same as the first form, except that |
|
|
640 | C<$rvport> defaults to C<$SELF>. |
|
|
641 | |
|
|
642 | The remaining forms don't distinguish between "normal" and "abnormal" kil's |
|
|
643 | - it's up to the callback or receiver to check whether the C<@reason> is |
|
|
644 | empty and act accordingly. |
|
|
645 | |
543 | In the first form (callback), the callback is simply called with any |
646 | In the third form (callback), the callback is simply called with any |
544 | number of C<@reason> elements (no @reason means that the port was deleted |
647 | number of C<@reason> elements (empty @reason means that the port was deleted |
545 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
648 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
546 | C<eval> if unsure. |
649 | C<eval> if unsure. |
547 | |
650 | |
548 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
549 | will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on |
|
|
550 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
551 | port is killed with the same reason. |
|
|
552 | |
|
|
553 | The third form (kill self) is the same as the second form, except that |
|
|
554 | C<$rvport> defaults to C<$SELF>. |
|
|
555 | |
|
|
556 | In the last form (message), a message of the form C<@msg, @reason> will be |
651 | In the last form (message), a message of the form C<$rcvport, @msg, |
557 | C<snd>. |
652 | @reason> will be C<snd>. |
558 | |
653 | |
559 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
654 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
560 | alert was raised), they are removed and will not trigger again. |
655 | alert was raised), they are removed and will not trigger again, even if it |
|
|
656 | turns out that the port is still alive. |
561 | |
657 | |
562 | As a rule of thumb, monitoring requests should always monitor a port from |
658 | As a rule of thumb, monitoring requests should always monitor a remote |
563 | a local port (or callback). The reason is that kill messages might get |
659 | port locally (using a local C<$rcvport> or a callback). The reason is that |
564 | lost, just like any other message. Another less obvious reason is that |
660 | kill messages might get lost, just like any other message. Another less |
565 | even monitoring requests can get lost (for example, when the connection |
661 | obvious reason is that even monitoring requests can get lost (for example, |
566 | to the other node goes down permanently). When monitoring a port locally |
662 | when the connection to the other node goes down permanently). When |
567 | these problems do not exist. |
663 | monitoring a port locally these problems do not exist. |
568 | |
664 | |
569 | C<mon> effectively guarantees that, in the absence of hardware failures, |
665 | C<mon> effectively guarantees that, in the absence of hardware failures, |
570 | after starting the monitor, either all messages sent to the port will |
666 | after starting the monitor, either all messages sent to the port will |
571 | arrive, or the monitoring action will be invoked after possible message |
667 | arrive, or the monitoring action will be invoked after possible message |
572 | loss has been detected. No messages will be lost "in between" (after |
668 | loss has been detected. No messages will be lost "in between" (after |
… | |
… | |
617 | } |
713 | } |
618 | |
714 | |
619 | $node->monitor ($port, $cb); |
715 | $node->monitor ($port, $cb); |
620 | |
716 | |
621 | defined wantarray |
717 | defined wantarray |
622 | and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }) |
718 | and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) }) |
623 | } |
719 | } |
624 | |
720 | |
625 | =item $guard = mon_guard $port, $ref, $ref... |
721 | =item $guard = mon_guard $port, $ref, $ref... |
626 | |
722 | |
627 | Monitors the given C<$port> and keeps the passed references. When the port |
723 | Monitors the given C<$port> and keeps the passed references. When the port |
… | |
… | |
650 | |
746 | |
651 | =item kil $port[, @reason] |
747 | =item kil $port[, @reason] |
652 | |
748 | |
653 | Kill the specified port with the given C<@reason>. |
749 | Kill the specified port with the given C<@reason>. |
654 | |
750 | |
655 | If no C<@reason> is specified, then the port is killed "normally" (ports |
751 | If no C<@reason> is specified, then the port is killed "normally" - |
656 | monitoring other ports will not necessarily die because a port dies |
752 | monitor callback will be invoked, but the kil will not cause linked ports |
657 | "normally"). |
753 | (C<mon $mport, $lport> form) to get killed. |
658 | |
754 | |
659 | Otherwise, linked ports get killed with the same reason (second form of |
755 | If a C<@reason> is specified, then linked ports (C<mon $mport, $lport> |
660 | C<mon>, see above). |
756 | form) get killed with the same reason. |
661 | |
757 | |
662 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
758 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
663 | will be reported as reason C<< die => $@ >>. |
759 | will be reported as reason C<< die => $@ >>. |
664 | |
760 | |
665 | Transport/communication errors are reported as C<< transport_error => |
761 | Transport/communication errors are reported as C<< transport_error => |
666 | $message >>. |
762 | $message >>. |
667 | |
763 | |
668 | =cut |
764 | Common idioms: |
|
|
765 | |
|
|
766 | # silently remove yourself, do not kill linked ports |
|
|
767 | kil $SELF; |
|
|
768 | |
|
|
769 | # report a failure in some detail |
|
|
770 | kil $SELF, failure_mode_1 => "it failed with too high temperature"; |
|
|
771 | |
|
|
772 | # do not waste much time with killing, just die when something goes wrong |
|
|
773 | open my $fh, "<file" |
|
|
774 | or die "file: $!"; |
669 | |
775 | |
670 | =item $port = spawn $node, $initfunc[, @initdata] |
776 | =item $port = spawn $node, $initfunc[, @initdata] |
671 | |
777 | |
672 | Creates a port on the node C<$node> (which can also be a port ID, in which |
778 | Creates a port on the node C<$node> (which can also be a port ID, in which |
673 | case it's the node where that port resides). |
779 | case it's the node where that port resides). |
… | |
… | |
731 | } |
837 | } |
732 | |
838 | |
733 | sub spawn(@) { |
839 | sub spawn(@) { |
734 | my ($nodeid, undef) = split /#/, shift, 2; |
840 | my ($nodeid, undef) = split /#/, shift, 2; |
735 | |
841 | |
736 | my $id = "$RUNIQ." . $ID++; |
842 | my $id = $RUNIQ . ++$ID; |
737 | |
843 | |
738 | $_[0] =~ /::/ |
844 | $_[0] =~ /::/ |
739 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
845 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
740 | |
846 | |
741 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
847 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
742 | |
848 | |
743 | "$nodeid#$id" |
849 | "$nodeid#$id" |
744 | } |
850 | } |
|
|
851 | |
745 | |
852 | |
746 | =item after $timeout, @msg |
853 | =item after $timeout, @msg |
747 | |
854 | |
748 | =item after $timeout, $callback |
855 | =item after $timeout, $callback |
749 | |
856 | |
… | |
… | |
764 | ref $action[0] |
871 | ref $action[0] |
765 | ? $action[0]() |
872 | ? $action[0]() |
766 | : snd @action; |
873 | : snd @action; |
767 | }; |
874 | }; |
768 | } |
875 | } |
|
|
876 | |
|
|
877 | #=item $cb2 = timeout $seconds, $cb[, @args] |
769 | |
878 | |
770 | =item cal $port, @msg, $callback[, $timeout] |
879 | =item cal $port, @msg, $callback[, $timeout] |
771 | |
880 | |
772 | A simple form of RPC - sends a message to the given C<$port> with the |
881 | A simple form of RPC - sends a message to the given C<$port> with the |
773 | given contents (C<@msg>), but adds a reply port to the message. |
882 | given contents (C<@msg>), but adds a reply port to the message. |
… | |
… | |
819 | $port |
928 | $port |
820 | } |
929 | } |
821 | |
930 | |
822 | =back |
931 | =back |
823 | |
932 | |
|
|
933 | =head1 DISTRIBUTED DATABASE |
|
|
934 | |
|
|
935 | AnyEvent::MP comes with a simple distributed database. The database will |
|
|
936 | be mirrored asynchronously on all global nodes. Other nodes bind to one |
|
|
937 | of the global nodes for their needs. Every node has a "local database" |
|
|
938 | which contains all the values that are set locally. All local databases |
|
|
939 | are merged together to form the global database, which can be queried. |
|
|
940 | |
|
|
941 | The database structure is that of a two-level hash - the database hash |
|
|
942 | contains hashes which contain values, similarly to a perl hash of hashes, |
|
|
943 | i.e.: |
|
|
944 | |
|
|
945 | $DATABASE{$family}{$subkey} = $value |
|
|
946 | |
|
|
947 | The top level hash key is called "family", and the second-level hash key |
|
|
948 | is called "subkey" or simply "key". |
|
|
949 | |
|
|
950 | The family must be alphanumeric, i.e. start with a letter and consist |
|
|
951 | of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>, |
|
|
952 | pretty much like Perl module names. |
|
|
953 | |
|
|
954 | As the family namespace is global, it is recommended to prefix family names |
|
|
955 | with the name of the application or module using it. |
|
|
956 | |
|
|
957 | The subkeys must be non-empty strings, with no further restrictions. |
|
|
958 | |
|
|
959 | The values should preferably be strings, but other perl scalars should |
|
|
960 | work as well (such as C<undef>, arrays and hashes). |
|
|
961 | |
|
|
962 | Every database entry is owned by one node - adding the same family/subkey |
|
|
963 | combination on multiple nodes will not cause discomfort for AnyEvent::MP, |
|
|
964 | but the result might be nondeterministic, i.e. the key might have |
|
|
965 | different values on different nodes. |
|
|
966 | |
|
|
967 | Different subkeys in the same family can be owned by different nodes |
|
|
968 | without problems, and in fact, this is the common method to create worker |
|
|
969 | pools. For example, a worker port for image scaling might do this: |
|
|
970 | |
|
|
971 | db_set my_image_scalers => $port; |
|
|
972 | |
|
|
973 | And clients looking for an image scaler will want to get the |
|
|
974 | C<my_image_scalers> keys from time to time: |
|
|
975 | |
|
|
976 | db_keys my_image_scalers => sub { |
|
|
977 | @ports = @{ $_[0] }; |
|
|
978 | }; |
|
|
979 | |
|
|
980 | Or better yet, they want to monitor the database family, so they always |
|
|
981 | have a reasonable up-to-date copy: |
|
|
982 | |
|
|
983 | db_mon my_image_scalers => sub { |
|
|
984 | @ports = keys %{ $_[0] }; |
|
|
985 | }; |
|
|
986 | |
|
|
987 | In general, you can set or delete single subkeys, but query and monitor |
|
|
988 | whole families only. |
|
|
989 | |
|
|
990 | If you feel the need to monitor or query a single subkey, try giving it |
|
|
991 | it's own family. |
|
|
992 | |
|
|
993 | =over |
|
|
994 | |
|
|
995 | =item $guard = db_set $family => $subkey [=> $value] |
|
|
996 | |
|
|
997 | Sets (or replaces) a key to the database - if C<$value> is omitted, |
|
|
998 | C<undef> is used instead. |
|
|
999 | |
|
|
1000 | When called in non-void context, C<db_set> returns a guard that |
|
|
1001 | automatically calls C<db_del> when it is destroyed. |
|
|
1002 | |
|
|
1003 | =item db_del $family => $subkey... |
|
|
1004 | |
|
|
1005 | Deletes one or more subkeys from the database family. |
|
|
1006 | |
|
|
1007 | =item $guard = db_reg $family => $port => $value |
|
|
1008 | |
|
|
1009 | =item $guard = db_reg $family => $port |
|
|
1010 | |
|
|
1011 | =item $guard = db_reg $family |
|
|
1012 | |
|
|
1013 | Registers a port in the given family and optionally returns a guard to |
|
|
1014 | remove it. |
|
|
1015 | |
|
|
1016 | This function basically does the same as: |
|
|
1017 | |
|
|
1018 | db_set $family => $port => $value |
|
|
1019 | |
|
|
1020 | Except that the port is monitored and automatically removed from the |
|
|
1021 | database family when it is kil'ed. |
|
|
1022 | |
|
|
1023 | If C<$value> is missing, C<undef> is used. If C<$port> is missing, then |
|
|
1024 | C<$SELF> is used. |
|
|
1025 | |
|
|
1026 | This function is most useful to register a port in some port group (which |
|
|
1027 | is just another name for a database family), and have it removed when the |
|
|
1028 | port is gone. This works best when the port is a local port. |
|
|
1029 | |
|
|
1030 | =cut |
|
|
1031 | |
|
|
1032 | sub db_reg($$;$) { |
|
|
1033 | my $family = shift; |
|
|
1034 | my $port = @_ ? shift : $SELF; |
|
|
1035 | |
|
|
1036 | my $clr = sub { db_del $family => $port }; |
|
|
1037 | mon $port, $clr; |
|
|
1038 | |
|
|
1039 | db_set $family => $port => $_[0]; |
|
|
1040 | |
|
|
1041 | defined wantarray |
|
|
1042 | and &Guard::guard ($clr) |
|
|
1043 | } |
|
|
1044 | |
|
|
1045 | =item db_family $family => $cb->(\%familyhash) |
|
|
1046 | |
|
|
1047 | Queries the named database C<$family> and call the callback with the |
|
|
1048 | family represented as a hash. You can keep and freely modify the hash. |
|
|
1049 | |
|
|
1050 | =item db_keys $family => $cb->(\@keys) |
|
|
1051 | |
|
|
1052 | Same as C<db_family>, except it only queries the family I<subkeys> and passes |
|
|
1053 | them as array reference to the callback. |
|
|
1054 | |
|
|
1055 | =item db_values $family => $cb->(\@values) |
|
|
1056 | |
|
|
1057 | Same as C<db_family>, except it only queries the family I<values> and passes them |
|
|
1058 | as array reference to the callback. |
|
|
1059 | |
|
|
1060 | =item $guard = db_mon $family => $cb->(\%familyhash, \@added, \@changed, \@deleted) |
|
|
1061 | |
|
|
1062 | Creates a monitor on the given database family. Each time a key is |
|
|
1063 | set or is deleted the callback is called with a hash containing the |
|
|
1064 | database family and three lists of added, changed and deleted subkeys, |
|
|
1065 | respectively. If no keys have changed then the array reference might be |
|
|
1066 | C<undef> or even missing. |
|
|
1067 | |
|
|
1068 | If not called in void context, a guard object is returned that, when |
|
|
1069 | destroyed, stops the monitor. |
|
|
1070 | |
|
|
1071 | The family hash reference and the key arrays belong to AnyEvent::MP and |
|
|
1072 | B<must not be modified or stored> by the callback. When in doubt, make a |
|
|
1073 | copy. |
|
|
1074 | |
|
|
1075 | As soon as possible after the monitoring starts, the callback will be |
|
|
1076 | called with the intiial contents of the family, even if it is empty, |
|
|
1077 | i.e. there will always be a timely call to the callback with the current |
|
|
1078 | contents. |
|
|
1079 | |
|
|
1080 | It is possible that the callback is called with a change event even though |
|
|
1081 | the subkey is already present and the value has not changed. |
|
|
1082 | |
|
|
1083 | The monitoring stops when the guard object is destroyed. |
|
|
1084 | |
|
|
1085 | Example: on every change to the family "mygroup", print out all keys. |
|
|
1086 | |
|
|
1087 | my $guard = db_mon mygroup => sub { |
|
|
1088 | my ($family, $a, $c, $d) = @_; |
|
|
1089 | print "mygroup members: ", (join " ", keys %$family), "\n"; |
|
|
1090 | }; |
|
|
1091 | |
|
|
1092 | Exmaple: wait until the family "My::Module::workers" is non-empty. |
|
|
1093 | |
|
|
1094 | my $guard; $guard = db_mon My::Module::workers => sub { |
|
|
1095 | my ($family, $a, $c, $d) = @_; |
|
|
1096 | return unless %$family; |
|
|
1097 | undef $guard; |
|
|
1098 | print "My::Module::workers now nonempty\n"; |
|
|
1099 | }; |
|
|
1100 | |
|
|
1101 | Example: print all changes to the family "AnyEvent::Fantasy::Module". |
|
|
1102 | |
|
|
1103 | my $guard = db_mon AnyEvent::Fantasy::Module => sub { |
|
|
1104 | my ($family, $a, $c, $d) = @_; |
|
|
1105 | |
|
|
1106 | print "+$_=$family->{$_}\n" for @$a; |
|
|
1107 | print "*$_=$family->{$_}\n" for @$c; |
|
|
1108 | print "-$_=$family->{$_}\n" for @$d; |
|
|
1109 | }; |
|
|
1110 | |
|
|
1111 | =cut |
|
|
1112 | |
|
|
1113 | =back |
|
|
1114 | |
824 | =head1 AnyEvent::MP vs. Distributed Erlang |
1115 | =head1 AnyEvent::MP vs. Distributed Erlang |
825 | |
1116 | |
826 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
1117 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
827 | == aemp node, Erlang process == aemp port), so many of the documents and |
1118 | == aemp node, Erlang process == aemp port), so many of the documents and |
828 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
1119 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
… | |
… | |
859 | ports being the special case/exception, where transport errors cannot |
1150 | ports being the special case/exception, where transport errors cannot |
860 | occur. |
1151 | occur. |
861 | |
1152 | |
862 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
1153 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
863 | |
1154 | |
864 | Erlang uses processes that selectively receive messages, and therefore |
1155 | Erlang uses processes that selectively receive messages out of order, and |
865 | needs a queue. AEMP is event based, queuing messages would serve no |
1156 | therefore needs a queue. AEMP is event based, queuing messages would serve |
866 | useful purpose. For the same reason the pattern-matching abilities of |
1157 | no useful purpose. For the same reason the pattern-matching abilities |
867 | AnyEvent::MP are more limited, as there is little need to be able to |
1158 | of AnyEvent::MP are more limited, as there is little need to be able to |
868 | filter messages without dequeuing them. |
1159 | filter messages without dequeuing them. |
869 | |
1160 | |
870 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
1161 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
|
|
1162 | being event-based, while Erlang is process-based. |
|
|
1163 | |
|
|
1164 | You can have a look at L<Coro::MP> for a more Erlang-like process model on |
|
|
1165 | top of AEMP and Coro threads. |
871 | |
1166 | |
872 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
1167 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
873 | |
1168 | |
874 | Sending messages in Erlang is synchronous and blocks the process (and |
1169 | Sending messages in Erlang is synchronous and blocks the process until |
|
|
1170 | a connection has been established and the message sent (and so does not |
875 | so does not need a queue that can overflow). AEMP sends are immediate, |
1171 | need a queue that can overflow). AEMP sends return immediately, connection |
876 | connection establishment is handled in the background. |
1172 | establishment is handled in the background. |
877 | |
1173 | |
878 | =item * Erlang suffers from silent message loss, AEMP does not. |
1174 | =item * Erlang suffers from silent message loss, AEMP does not. |
879 | |
1175 | |
880 | Erlang implements few guarantees on messages delivery - messages can get |
1176 | Erlang implements few guarantees on messages delivery - messages can get |
881 | lost without any of the processes realising it (i.e. you send messages a, |
1177 | lost without any of the processes realising it (i.e. you send messages a, |
882 | b, and c, and the other side only receives messages a and c). |
1178 | b, and c, and the other side only receives messages a and c). |
883 | |
1179 | |
884 | AEMP guarantees correct ordering, and the guarantee that after one message |
1180 | AEMP guarantees (modulo hardware errors) correct ordering, and the |
885 | is lost, all following ones sent to the same port are lost as well, until |
1181 | guarantee that after one message is lost, all following ones sent to the |
886 | monitoring raises an error, so there are no silent "holes" in the message |
1182 | same port are lost as well, until monitoring raises an error, so there are |
887 | sequence. |
1183 | no silent "holes" in the message sequence. |
|
|
1184 | |
|
|
1185 | If you want your software to be very reliable, you have to cope with |
|
|
1186 | corrupted and even out-of-order messages in both Erlang and AEMP. AEMP |
|
|
1187 | simply tries to work better in common error cases, such as when a network |
|
|
1188 | link goes down. |
888 | |
1189 | |
889 | =item * Erlang can send messages to the wrong port, AEMP does not. |
1190 | =item * Erlang can send messages to the wrong port, AEMP does not. |
890 | |
1191 | |
891 | In Erlang it is quite likely that a node that restarts reuses a process ID |
1192 | In Erlang it is quite likely that a node that restarts reuses an Erlang |
892 | known to other nodes for a completely different process, causing messages |
1193 | process ID known to other nodes for a completely different process, |
893 | destined for that process to end up in an unrelated process. |
1194 | causing messages destined for that process to end up in an unrelated |
|
|
1195 | process. |
894 | |
1196 | |
895 | AEMP never reuses port IDs, so old messages or old port IDs floating |
1197 | AEMP does not reuse port IDs, so old messages or old port IDs floating |
896 | around in the network will not be sent to an unrelated port. |
1198 | around in the network will not be sent to an unrelated port. |
897 | |
1199 | |
898 | =item * Erlang uses unprotected connections, AEMP uses secure |
1200 | =item * Erlang uses unprotected connections, AEMP uses secure |
899 | authentication and can use TLS. |
1201 | authentication and can use TLS. |
900 | |
1202 | |
… | |
… | |
903 | |
1205 | |
904 | =item * The AEMP protocol is optimised for both text-based and binary |
1206 | =item * The AEMP protocol is optimised for both text-based and binary |
905 | communications. |
1207 | communications. |
906 | |
1208 | |
907 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
1209 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
908 | language independent text-only protocols (good for debugging) and binary, |
1210 | language independent text-only protocols (good for debugging), and binary, |
909 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
1211 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
910 | used, the protocol is actually completely text-based. |
1212 | used, the protocol is actually completely text-based. |
911 | |
1213 | |
912 | It has also been carefully designed to be implementable in other languages |
1214 | It has also been carefully designed to be implementable in other languages |
913 | with a minimum of work while gracefully degrading functionality to make the |
1215 | with a minimum of work while gracefully degrading functionality to make the |
914 | protocol simple. |
1216 | protocol simple. |
915 | |
1217 | |
916 | =item * AEMP has more flexible monitoring options than Erlang. |
1218 | =item * AEMP has more flexible monitoring options than Erlang. |
917 | |
1219 | |
918 | In Erlang, you can chose to receive I<all> exit signals as messages |
1220 | In Erlang, you can chose to receive I<all> exit signals as messages or |
919 | or I<none>, there is no in-between, so monitoring single processes is |
1221 | I<none>, there is no in-between, so monitoring single Erlang processes is |
920 | difficult to implement. Monitoring in AEMP is more flexible than in |
1222 | difficult to implement. |
921 | Erlang, as one can choose between automatic kill, exit message or callback |
1223 | |
922 | on a per-process basis. |
1224 | Monitoring in AEMP is more flexible than in Erlang, as one can choose |
|
|
1225 | between automatic kill, exit message or callback on a per-port basis. |
923 | |
1226 | |
924 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
1227 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
925 | |
1228 | |
926 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
1229 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
927 | same way as linking is (except linking is unreliable in Erlang). |
1230 | same way as linking is (except linking is unreliable in Erlang). |
… | |
… | |
949 | overhead, as well as having to keep a proxy object everywhere. |
1252 | overhead, as well as having to keep a proxy object everywhere. |
950 | |
1253 | |
951 | Strings can easily be printed, easily serialised etc. and need no special |
1254 | Strings can easily be printed, easily serialised etc. and need no special |
952 | procedures to be "valid". |
1255 | procedures to be "valid". |
953 | |
1256 | |
954 | And as a result, a miniport consists of a single closure stored in a |
1257 | And as a result, a port with just a default receiver consists of a single |
955 | global hash - it can't become much cheaper. |
1258 | code reference stored in a global hash - it can't become much cheaper. |
956 | |
1259 | |
957 | =item Why favour JSON, why not a real serialising format such as Storable? |
1260 | =item Why favour JSON, why not a real serialising format such as Storable? |
958 | |
1261 | |
959 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
1262 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
960 | format, but currently there is no way to make a node use Storable by |
1263 | format, but currently there is no way to make a node use Storable by |
… | |
… | |
970 | Keeping your messages simple, concentrating on data structures rather than |
1273 | Keeping your messages simple, concentrating on data structures rather than |
971 | objects, will keep your messages clean, tidy and efficient. |
1274 | objects, will keep your messages clean, tidy and efficient. |
972 | |
1275 | |
973 | =back |
1276 | =back |
974 | |
1277 | |
|
|
1278 | =head1 PORTING FROM AnyEvent::MP VERSION 1.X |
|
|
1279 | |
|
|
1280 | AEMP version 2 has a few major incompatible changes compared to version 1: |
|
|
1281 | |
|
|
1282 | =over 4 |
|
|
1283 | |
|
|
1284 | =item AnyEvent::MP::Global no longer has group management functions. |
|
|
1285 | |
|
|
1286 | At least not officially - the grp_* functions are still exported and might |
|
|
1287 | work, but they will be removed in some later release. |
|
|
1288 | |
|
|
1289 | AnyEvent::MP now comes with a distributed database that is more |
|
|
1290 | powerful. Its database families map closely to port groups, but the API |
|
|
1291 | has changed (the functions are also now exported by AnyEvent::MP). Here is |
|
|
1292 | a rough porting guide: |
|
|
1293 | |
|
|
1294 | grp_reg $group, $port # old |
|
|
1295 | db_reg $group, $port # new |
|
|
1296 | |
|
|
1297 | $list = grp_get $group # old |
|
|
1298 | db_keys $group, sub { my $list = shift } # new |
|
|
1299 | |
|
|
1300 | grp_mon $group, $cb->(\@ports, $add, $del) # old |
|
|
1301 | db_mon $group, $cb->(\%ports, $add, $change, $del) # new |
|
|
1302 | |
|
|
1303 | C<grp_reg> is a no-brainer (just replace by C<db_reg>), but C<grp_get> is |
|
|
1304 | no longer instant, because the local node might not have a copy of the |
|
|
1305 | group. You can either modify your code to allow for a callback, or use |
|
|
1306 | C<db_mon> to keep an updated copy of the group: |
|
|
1307 | |
|
|
1308 | my $local_group_copy; |
|
|
1309 | db_mon $group => sub { $local_group_copy = $_[0] }; |
|
|
1310 | |
|
|
1311 | # now "keys %$local_group_copy" always returns the most up-to-date |
|
|
1312 | # list of ports in the group. |
|
|
1313 | |
|
|
1314 | C<grp_mon> can be replaced by C<db_mon> with minor changes - C<db_mon> |
|
|
1315 | passes a hash as first argument, and an extra C<$chg> argument that can be |
|
|
1316 | ignored: |
|
|
1317 | |
|
|
1318 | db_mon $group => sub { |
|
|
1319 | my ($ports, $add, $chg, $lde) = @_; |
|
|
1320 | $ports = [keys %$ports]; |
|
|
1321 | |
|
|
1322 | # now $ports, $add and $del are the same as |
|
|
1323 | # were originally passed by grp_mon. |
|
|
1324 | ... |
|
|
1325 | }; |
|
|
1326 | |
|
|
1327 | =item Nodes not longer connect to all other nodes. |
|
|
1328 | |
|
|
1329 | In AEMP 1.x, every node automatically loads the L<AnyEvent::MP::Global> |
|
|
1330 | module, which in turn would create connections to all other nodes in the |
|
|
1331 | network (helped by the seed nodes). |
|
|
1332 | |
|
|
1333 | In version 2.x, global nodes still connect to all other global nodes, but |
|
|
1334 | other nodes don't - now every node either is a global node itself, or |
|
|
1335 | attaches itself to another global node. |
|
|
1336 | |
|
|
1337 | If a node isn't a global node itself, then it attaches itself to one |
|
|
1338 | of its seed nodes. If that seed node isn't a global node yet, it will |
|
|
1339 | automatically be upgraded to a global node. |
|
|
1340 | |
|
|
1341 | So in many cases, nothing needs to be changed - one just has to make sure |
|
|
1342 | that all seed nodes are meshed together with the other seed nodes (as with |
|
|
1343 | AEMP 1.x), and other nodes specify them as seed nodes. This is most easily |
|
|
1344 | achieved by specifying the same set of seed nodes for all nodes in the |
|
|
1345 | network. |
|
|
1346 | |
|
|
1347 | Not opening a connection to every other node is usually an advantage, |
|
|
1348 | except when you need the lower latency of an already established |
|
|
1349 | connection. To ensure a node establishes a connection to another node, |
|
|
1350 | you can monitor the node port (C<mon $node, ...>), which will attempt to |
|
|
1351 | create the connection (and notify you when the connection fails). |
|
|
1352 | |
|
|
1353 | =item Listener-less nodes (nodes without binds) are gone. |
|
|
1354 | |
|
|
1355 | And are not coming back, at least not in their old form. If no C<binds> |
|
|
1356 | are specified for a node, AnyEvent::MP assumes a default of C<*:*>. |
|
|
1357 | |
|
|
1358 | There are vague plans to implement some form of routing domains, which |
|
|
1359 | might or might not bring back listener-less nodes, but don't count on it. |
|
|
1360 | |
|
|
1361 | The fact that most connections are now optional somewhat mitigates this, |
|
|
1362 | as a node can be effectively unreachable from the outside without any |
|
|
1363 | problems, as long as it isn't a global node and only reaches out to other |
|
|
1364 | nodes (as opposed to being contacted from other nodes). |
|
|
1365 | |
|
|
1366 | =item $AnyEvent::MP::Kernel::WARN has gone. |
|
|
1367 | |
|
|
1368 | AnyEvent has acquired a logging framework (L<AnyEvent::Log>), and AEMP now |
|
|
1369 | uses this, and so should your programs. |
|
|
1370 | |
|
|
1371 | Every module now documents what kinds of messages it generates, with |
|
|
1372 | AnyEvent::MP acting as a catch all. |
|
|
1373 | |
|
|
1374 | On the positive side, this means that instead of setting |
|
|
1375 | C<PERL_ANYEVENT_MP_WARNLEVEL>, you can get away by setting C<AE_VERBOSE> - |
|
|
1376 | much less to type. |
|
|
1377 | |
|
|
1378 | =back |
|
|
1379 | |
|
|
1380 | =head1 LOGGING |
|
|
1381 | |
|
|
1382 | AnyEvent::MP does not normally log anything by itself, but since it is the |
|
|
1383 | root of the contetx hierarchy for AnyEvent::MP modules, it will receive |
|
|
1384 | all log messages by submodules. |
|
|
1385 | |
975 | =head1 SEE ALSO |
1386 | =head1 SEE ALSO |
976 | |
1387 | |
977 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1388 | L<AnyEvent::MP::Intro> - a gentle introduction. |
978 | |
1389 | |
979 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
1390 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
980 | |
1391 | |
981 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
1392 | L<AnyEvent::MP::Global> - network maintenance and port groups, to find |
982 | your applications. |
1393 | your applications. |
|
|
1394 | |
|
|
1395 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
983 | |
1396 | |
984 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
1397 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
985 | all nodes. |
1398 | all nodes. |
986 | |
1399 | |
987 | L<AnyEvent>. |
1400 | L<AnyEvent>. |