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 | |
9 | $NODE # contains this node's noderef |
9 | $NODE # contains this node's node ID |
10 | NODE # returns this node's noderef |
10 | NODE # returns this node's node ID |
11 | NODE $port # returns the noderef of the port |
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12 | |
11 | |
13 | $SELF # receiving/own port id in rcv callbacks |
12 | $SELF # receiving/own port id in rcv callbacks |
14 | |
13 | |
15 | # initialise the node so it can send/receive messages |
14 | # initialise the node so it can send/receive messages |
16 | configure; |
15 | configure; |
17 | |
16 | |
18 | # ports are message endpoints |
17 | # ports are message destinations |
19 | |
18 | |
20 | # sending messages |
19 | # sending messages |
21 | snd $port, type => data...; |
20 | snd $port, type => data...; |
22 | snd $port, @msg; |
21 | snd $port, @msg; |
23 | snd @msg_with_first_element_being_a_port; |
22 | snd @msg_with_first_element_being_a_port; |
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31 | rcv $port, pong => sub { warn "pong received\n" }; |
30 | rcv $port, pong => sub { warn "pong received\n" }; |
32 | |
31 | |
33 | # create a port on another node |
32 | # create a port on another node |
34 | my $port = spawn $node, $initfunc, @initdata; |
33 | my $port = spawn $node, $initfunc, @initdata; |
35 | |
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 | |
36 | # monitoring |
39 | # monitoring |
37 | mon $port, $cb->(@msg) # callback is invoked on death |
40 | mon $port, $cb->(@msg) # callback is invoked on death |
38 | mon $port, $otherport # kill otherport on abnormal death |
41 | mon $port, $localport # kill localport on abnormal death |
39 | mon $port, $otherport, @msg # send message on death |
42 | mon $port, $localport, @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 | }; |
40 | |
51 | |
41 | =head1 CURRENT STATUS |
52 | =head1 CURRENT STATUS |
42 | |
53 | |
43 | bin/aemp - stable. |
54 | bin/aemp - stable. |
44 | AnyEvent::MP - stable API, should work. |
55 | AnyEvent::MP - stable API, should work. |
45 | AnyEvent::MP::Intro - uptodate, but incomplete. |
56 | AnyEvent::MP::Intro - explains most concepts. |
46 | AnyEvent::MP::Kernel - mostly stable. |
57 | AnyEvent::MP::Kernel - mostly stable API. |
47 | AnyEvent::MP::Global - stable API, protocol not yet final. |
58 | AnyEvent::MP::Global - stable API. |
48 | |
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49 | stay tuned. |
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50 | |
59 | |
51 | =head1 DESCRIPTION |
60 | =head1 DESCRIPTION |
52 | |
61 | |
53 | This module (-family) implements a simple message passing framework. |
62 | This module (-family) implements a simple message passing framework. |
54 | |
63 | |
… | |
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56 | on the same or other hosts, and you can supervise entities remotely. |
65 | on the same or other hosts, and you can supervise entities remotely. |
57 | |
66 | |
58 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
67 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
59 | manual page and the examples under F<eg/>. |
68 | manual page and the examples under F<eg/>. |
60 | |
69 | |
61 | At the moment, this module family is a bit underdocumented. |
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62 | |
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63 | =head1 CONCEPTS |
70 | =head1 CONCEPTS |
64 | |
71 | |
65 | =over 4 |
72 | =over 4 |
66 | |
73 | |
67 | =item port |
74 | =item port |
68 | |
75 | |
69 | A port is something you can send messages to (with the C<snd> function). |
76 | Not to be confused with a TCP port, a "port" is something you can send |
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77 | messages to (with the C<snd> function). |
70 | |
78 | |
71 | 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 |
72 | 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 |
73 | anything was listening for them or not. |
81 | anything was listening for them or not. |
74 | |
82 | |
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83 | Ports are represented by (printable) strings called "port IDs". |
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84 | |
75 | =item port ID - C<nodeid#portname> |
85 | =item port ID - C<nodeid#portname> |
76 | |
86 | |
77 | 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<#>) |
78 | 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). |
79 | |
90 | |
80 | =item node |
91 | =item node |
81 | |
92 | |
82 | 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, |
83 | 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 |
84 | ports. |
95 | ports. |
85 | |
96 | |
86 | 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 |
87 | (no listening ports). Private nodes cannot talk to other private nodes |
98 | (no listening ports). Private nodes cannot talk to other private nodes |
88 | currently. |
99 | currently, but all nodes can talk to public nodes. |
89 | |
100 | |
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101 | Nodes is represented by (printable) strings called "node IDs". |
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102 | |
90 | =item node ID - C<[a-za-Z0-9_\-.:]+> |
103 | =item node ID - C<[A-Za-z0-9_\-.:]*> |
91 | |
104 | |
92 | 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 |
93 | 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 |
94 | 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 |
95 | doesn't interpret node IDs in any way. |
108 | doesn't interpret node IDs in any way except to uniquely identify a node. |
96 | |
109 | |
97 | =item binds - C<ip:port> |
110 | =item binds - C<ip:port> |
98 | |
111 | |
99 | 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 |
100 | 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 | |
101 | endpoints - binds. Currently, only standard C<ip:port> specifications can |
116 | Currently, only standard C<ip:port> specifications can be used, which |
102 | 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. |
103 | |
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 | |
104 | =item seeds - C<host:port> |
149 | =item seed IDs - C<host:port> |
105 | |
150 | |
106 | 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 |
107 | 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. |
108 | network. This node is called a seed. |
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109 | |
153 | |
110 | Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes |
154 | =item global nodes |
111 | are expected to be long-running, and at least one of those should always |
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112 | be available. When nodes run out of connections (e.g. due to a network |
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113 | error), they try to re-establish connections to some seednodes again to |
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114 | join the network. |
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115 | |
155 | |
116 | 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 |
117 | 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). |
118 | |
170 | |
119 | =back |
171 | =back |
120 | |
172 | |
121 | =head1 VARIABLES/FUNCTIONS |
173 | =head1 VARIABLES/FUNCTIONS |
122 | |
174 | |
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124 | |
176 | |
125 | =cut |
177 | =cut |
126 | |
178 | |
127 | package AnyEvent::MP; |
179 | package AnyEvent::MP; |
128 | |
180 | |
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181 | use AnyEvent::MP::Config (); |
129 | 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); |
130 | |
184 | |
131 | use common::sense; |
185 | use common::sense; |
132 | |
186 | |
133 | use Carp (); |
187 | use Carp (); |
134 | |
188 | |
135 | use AE (); |
189 | use AE (); |
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190 | use Guard (); |
136 | |
191 | |
137 | use base "Exporter"; |
192 | use base "Exporter"; |
138 | |
193 | |
139 | our $VERSION = $AnyEvent::MP::Kernel::VERSION; |
194 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
140 | |
195 | |
141 | our @EXPORT = qw( |
196 | our @EXPORT = qw( |
142 | NODE $NODE *SELF node_of after |
197 | NODE $NODE *SELF node_of after |
143 | configure |
198 | configure |
144 | snd rcv mon mon_guard kil reg psub spawn |
199 | snd rcv mon mon_guard kil psub peval spawn cal |
145 | port |
200 | port |
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201 | db_set db_del db_reg |
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202 | db_mon db_family db_keys db_values |
146 | ); |
203 | ); |
147 | |
204 | |
148 | our $SELF; |
205 | our $SELF; |
149 | |
206 | |
150 | sub _self_die() { |
207 | sub _self_die() { |
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161 | |
218 | |
162 | =item $nodeid = node_of $port |
219 | =item $nodeid = node_of $port |
163 | |
220 | |
164 | Extracts and returns the node ID from a port ID or a node ID. |
221 | Extracts and returns the node ID from a port ID or a node ID. |
165 | |
222 | |
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223 | =item configure $profile, key => value... |
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224 | |
166 | =item configure key => value... |
225 | =item configure key => value... |
167 | |
226 | |
168 | Before a node can talk to other nodes on the network (i.e. enter |
227 | Before a node can talk to other nodes on the network (i.e. enter |
169 | "distributed mode") it has to configure itself - the minimum a node needs |
228 | "distributed mode") it has to configure itself - the minimum a node needs |
170 | to know is its own name, and optionally it should know the addresses of |
229 | 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. |
230 | some other nodes in the network to discover other nodes. |
172 | |
231 | |
173 | This function configures a node - it must be called exactly once (or |
232 | This function configures a node - it must be called exactly once (or |
174 | never) before calling other AnyEvent::MP functions. |
233 | never) before calling other AnyEvent::MP functions. |
175 | |
234 | |
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235 | The key/value pairs are basically the same ones as documented for the |
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236 | F<aemp> command line utility (sans the set/del prefix), with these additions: |
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237 | |
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238 | =over 4 |
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239 | |
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240 | =item norc => $boolean (default false) |
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241 | |
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242 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
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243 | be consulted - all configuraiton options must be specified in the |
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244 | C<configure> call. |
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245 | |
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246 | =item force => $boolean (default false) |
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247 | |
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248 | IF true, then the values specified in the C<configure> will take |
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249 | precedence over any values configured via the rc file. The default is for |
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250 | the rc file to override any options specified in the program. |
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251 | |
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252 | =item secure => $pass->($nodeid) |
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253 | |
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254 | In addition to specifying a boolean, you can specify a code reference that |
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255 | is called for every remote execution attempt - the execution request is |
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256 | granted iff the callback returns a true value. |
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257 | |
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258 | See F<semp setsecure> for more info. |
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259 | |
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260 | =back |
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261 | |
176 | =over 4 |
262 | =over 4 |
177 | |
263 | |
178 | =item step 1, gathering configuration from profiles |
264 | =item step 1, gathering configuration from profiles |
179 | |
265 | |
180 | The function first looks up a profile in the aemp configuration (see the |
266 | The function first looks up a profile in the aemp configuration (see the |
181 | L<aemp> commandline utility). The profile name can be specified via the |
267 | L<aemp> commandline utility). The profile name can be specified via the |
182 | named C<profile> parameter. If it is missing, then the nodename (F<uname |
268 | named C<profile> parameter or can simply be the first parameter). If it is |
183 | -n>) will be used as profile name. |
269 | missing, then the nodename (F<uname -n>) will be used as profile name. |
184 | |
270 | |
185 | The profile data is then gathered as follows: |
271 | The profile data is then gathered as follows: |
186 | |
272 | |
187 | First, all remaining key => value pairs (all of which are conviniently |
273 | First, all remaining key => value pairs (all of which are conveniently |
188 | undocumented at the moment) will be interpreted as configuration |
274 | undocumented at the moment) will be interpreted as configuration |
189 | data. Then they will be overwritten by any values specified in the global |
275 | data. Then they will be overwritten by any values specified in the global |
190 | default configuration (see the F<aemp> utility), then the chain of |
276 | default configuration (see the F<aemp> utility), then the chain of |
191 | profiles chosen by the profile name (and any C<parent> attributes). |
277 | profiles chosen by the profile name (and any C<parent> attributes). |
192 | |
278 | |
193 | That means that the values specified in the profile have highest priority |
279 | That means that the values specified in the profile have highest priority |
194 | and the values specified directly via C<configure> have lowest priority, |
280 | and the values specified directly via C<configure> have lowest priority, |
195 | and can only be used to specify defaults. |
281 | and can only be used to specify defaults. |
196 | |
282 | |
197 | If the profile specifies a node ID, then this will become the node ID of |
283 | If the profile specifies a node ID, then this will become the node ID of |
198 | this process. If not, then the profile name will be used as node ID. The |
284 | this process. If not, then the profile name will be used as node ID, with |
199 | special node ID of C<anon/> will be replaced by a random node ID. |
285 | a unique randoms tring (C</%u>) appended. |
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286 | |
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287 | The node ID can contain some C<%> sequences that are expanded: C<%n> |
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288 | is expanded to the local nodename, C<%u> is replaced by a random |
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289 | strign to make the node unique. For example, the F<aemp> commandline |
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290 | utility uses C<aemp/%n/%u> as nodename, which might expand to |
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291 | C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>. |
200 | |
292 | |
201 | =item step 2, bind listener sockets |
293 | =item step 2, bind listener sockets |
202 | |
294 | |
203 | The next step is to look up the binds in the profile, followed by binding |
295 | The next step is to look up the binds in the profile, followed by binding |
204 | aemp protocol listeners on all binds specified (it is possible and valid |
296 | aemp protocol listeners on all binds specified (it is possible and valid |
… | |
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210 | used, meaning the node will bind on a dynamically-assigned port on every |
302 | used, meaning the node will bind on a dynamically-assigned port on every |
211 | local IP address it finds. |
303 | local IP address it finds. |
212 | |
304 | |
213 | =item step 3, connect to seed nodes |
305 | =item step 3, connect to seed nodes |
214 | |
306 | |
215 | As the last step, the seeds list from the profile is passed to the |
307 | As the last step, the seed ID list from the profile is passed to the |
216 | L<AnyEvent::MP::Global> module, which will then use it to keep |
308 | L<AnyEvent::MP::Global> module, which will then use it to keep |
217 | connectivity with at least one node at any point in time. |
309 | connectivity with at least one node at any point in time. |
218 | |
310 | |
219 | =back |
311 | =back |
220 | |
312 | |
221 | Example: become a distributed node using the locla node name as profile. |
313 | Example: become a distributed node using the local node name as profile. |
222 | This should be the most common form of invocation for "daemon"-type nodes. |
314 | This should be the most common form of invocation for "daemon"-type nodes. |
223 | |
315 | |
224 | configure |
316 | configure |
225 | |
317 | |
226 | Example: become an anonymous node. This form is often used for commandline |
318 | Example: become a semi-anonymous node. This form is often used for |
227 | clients. |
319 | commandline clients. |
228 | |
320 | |
229 | configure nodeid => "anon/"; |
321 | configure nodeid => "myscript/%n/%u"; |
230 | |
322 | |
231 | Example: configure a node using a profile called seed, which si suitable |
323 | Example: configure a node using a profile called seed, which is suitable |
232 | for a seed node as it binds on all local addresses on a fixed port (4040, |
324 | for a seed node as it binds on all local addresses on a fixed port (4040, |
233 | customary for aemp). |
325 | customary for aemp). |
234 | |
326 | |
235 | # use the aemp commandline utility |
327 | # use the aemp commandline utility |
236 | # aemp profile seed nodeid anon/ binds '*:4040' |
328 | # aemp profile seed binds '*:4040' |
237 | |
329 | |
238 | # then use it |
330 | # then use it |
239 | configure profile => "seed"; |
331 | configure profile => "seed"; |
240 | |
332 | |
241 | # or simply use aemp from the shell again: |
333 | # or simply use aemp from the shell again: |
… | |
… | |
306 | |
398 | |
307 | =cut |
399 | =cut |
308 | |
400 | |
309 | sub rcv($@); |
401 | sub rcv($@); |
310 | |
402 | |
311 | sub _kilme { |
403 | my $KILME = sub { |
312 | die "received message on port without callback"; |
404 | (my $tag = substr $_[0], 0, 30) =~ s/([\x20-\x7e])/./g; |
313 | } |
405 | kil $SELF, unhandled_message => "no callback found for message '$tag'"; |
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406 | }; |
314 | |
407 | |
315 | sub port(;&) { |
408 | sub port(;&) { |
316 | my $id = "$UNIQ." . $ID++; |
409 | my $id = $UNIQ . ++$ID; |
317 | my $port = "$NODE#$id"; |
410 | my $port = "$NODE#$id"; |
318 | |
411 | |
319 | rcv $port, shift || \&_kilme; |
412 | rcv $port, shift || $KILME; |
320 | |
413 | |
321 | $port |
414 | $port |
322 | } |
415 | } |
323 | |
416 | |
324 | =item rcv $local_port, $callback->(@msg) |
417 | =item rcv $local_port, $callback->(@msg) |
… | |
… | |
329 | |
422 | |
330 | The global C<$SELF> (exported by this module) contains C<$port> while |
423 | The global C<$SELF> (exported by this module) contains C<$port> while |
331 | executing the callback. Runtime errors during callback execution will |
424 | executing the callback. Runtime errors during callback execution will |
332 | result in the port being C<kil>ed. |
425 | result in the port being C<kil>ed. |
333 | |
426 | |
334 | The default callback received all messages not matched by a more specific |
427 | The default callback receives all messages not matched by a more specific |
335 | C<tag> match. |
428 | C<tag> match. |
336 | |
429 | |
337 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
430 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
338 | |
431 | |
339 | Register (or replace) callbacks to be called on messages starting with the |
432 | Register (or replace) callbacks to be called on messages starting with the |
… | |
… | |
360 | msg1 => sub { ... }, |
453 | msg1 => sub { ... }, |
361 | ... |
454 | ... |
362 | ; |
455 | ; |
363 | |
456 | |
364 | Example: temporarily register a rcv callback for a tag matching some port |
457 | 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. |
458 | (e.g. for an rpc reply) and unregister it after a message was received. |
366 | |
459 | |
367 | rcv $port, $otherport => sub { |
460 | rcv $port, $otherport => sub { |
368 | my @reply = @_; |
461 | my @reply = @_; |
369 | |
462 | |
370 | rcv $SELF, $otherport; |
463 | rcv $SELF, $otherport; |
… | |
… | |
372 | |
465 | |
373 | =cut |
466 | =cut |
374 | |
467 | |
375 | sub rcv($@) { |
468 | sub rcv($@) { |
376 | my $port = shift; |
469 | my $port = shift; |
377 | my ($noderef, $portid) = split /#/, $port, 2; |
470 | my ($nodeid, $portid) = split /#/, $port, 2; |
378 | |
471 | |
379 | $NODE{$noderef} == $NODE{""} |
472 | $NODE{$nodeid} == $NODE{""} |
380 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
473 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
381 | |
474 | |
382 | while (@_) { |
475 | while (@_) { |
383 | if (ref $_[0]) { |
476 | if (ref $_[0]) { |
384 | if (my $self = $PORT_DATA{$portid}) { |
477 | if (my $self = $PORT_DATA{$portid}) { |
385 | "AnyEvent::MP::Port" eq ref $self |
478 | "AnyEvent::MP::Port" eq ref $self |
386 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
479 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
387 | |
480 | |
388 | $self->[2] = shift; |
481 | $self->[0] = shift; |
389 | } else { |
482 | } else { |
390 | my $cb = shift; |
483 | my $cb = shift; |
391 | $PORT{$portid} = sub { |
484 | $PORT{$portid} = sub { |
392 | local $SELF = $port; |
485 | local $SELF = $port; |
393 | eval { &$cb }; _self_die if $@; |
486 | eval { &$cb }; _self_die if $@; |
394 | }; |
487 | }; |
395 | } |
488 | } |
396 | } elsif (defined $_[0]) { |
489 | } elsif (defined $_[0]) { |
397 | my $self = $PORT_DATA{$portid} ||= do { |
490 | my $self = $PORT_DATA{$portid} ||= do { |
398 | my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
491 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
399 | |
492 | |
400 | $PORT{$portid} = sub { |
493 | $PORT{$portid} = sub { |
401 | local $SELF = $port; |
494 | local $SELF = $port; |
402 | |
495 | |
403 | if (my $cb = $self->[1]{$_[0]}) { |
496 | if (my $cb = $self->[1]{$_[0]}) { |
… | |
… | |
425 | } |
518 | } |
426 | |
519 | |
427 | $port |
520 | $port |
428 | } |
521 | } |
429 | |
522 | |
|
|
523 | =item peval $port, $coderef[, @args] |
|
|
524 | |
|
|
525 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
|
|
526 | when the code throews an exception the C<$port> will be killed. |
|
|
527 | |
|
|
528 | Any remaining args will be passed to the callback. Any return values will |
|
|
529 | be returned to the caller. |
|
|
530 | |
|
|
531 | This is useful when you temporarily want to execute code in the context of |
|
|
532 | a port. |
|
|
533 | |
|
|
534 | Example: create a port and run some initialisation code in it's context. |
|
|
535 | |
|
|
536 | my $port = port { ... }; |
|
|
537 | |
|
|
538 | peval $port, sub { |
|
|
539 | init |
|
|
540 | or die "unable to init"; |
|
|
541 | }; |
|
|
542 | |
|
|
543 | =cut |
|
|
544 | |
|
|
545 | sub peval($$) { |
|
|
546 | local $SELF = shift; |
|
|
547 | my $cb = shift; |
|
|
548 | |
|
|
549 | if (wantarray) { |
|
|
550 | my @res = eval { &$cb }; |
|
|
551 | _self_die if $@; |
|
|
552 | @res |
|
|
553 | } else { |
|
|
554 | my $res = eval { &$cb }; |
|
|
555 | _self_die if $@; |
|
|
556 | $res |
|
|
557 | } |
|
|
558 | } |
|
|
559 | |
430 | =item $closure = psub { BLOCK } |
560 | =item $closure = psub { BLOCK } |
431 | |
561 | |
432 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
562 | 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> |
563 | 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. |
564 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
|
|
565 | |
|
|
566 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
|
|
567 | BLOCK }, @_ } >>. |
435 | |
568 | |
436 | This is useful when you register callbacks from C<rcv> callbacks: |
569 | This is useful when you register callbacks from C<rcv> callbacks: |
437 | |
570 | |
438 | rcv delayed_reply => sub { |
571 | rcv delayed_reply => sub { |
439 | my ($delay, @reply) = @_; |
572 | my ($delay, @reply) = @_; |
… | |
… | |
475 | |
608 | |
476 | Monitor the given port and do something when the port is killed or |
609 | Monitor the given port and do something when the port is killed or |
477 | messages to it were lost, and optionally return a guard that can be used |
610 | messages to it were lost, and optionally return a guard that can be used |
478 | to stop monitoring again. |
611 | to stop monitoring again. |
479 | |
612 | |
|
|
613 | In the first form (callback), the callback is simply called with any |
|
|
614 | number of C<@reason> elements (no @reason means that the port was deleted |
|
|
615 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
|
|
616 | C<eval> if unsure. |
|
|
617 | |
|
|
618 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
619 | will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on |
|
|
620 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
621 | port is killed with the same reason. |
|
|
622 | |
|
|
623 | The third form (kill self) is the same as the second form, except that |
|
|
624 | C<$rvport> defaults to C<$SELF>. |
|
|
625 | |
|
|
626 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
627 | C<snd>. |
|
|
628 | |
|
|
629 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
|
|
630 | alert was raised), they are removed and will not trigger again. |
|
|
631 | |
|
|
632 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
633 | a local port (or callback). The reason is that kill messages might get |
|
|
634 | lost, just like any other message. Another less obvious reason is that |
|
|
635 | even monitoring requests can get lost (for example, when the connection |
|
|
636 | to the other node goes down permanently). When monitoring a port locally |
|
|
637 | these problems do not exist. |
|
|
638 | |
480 | C<mon> effectively guarantees that, in the absence of hardware failures, |
639 | C<mon> effectively guarantees that, in the absence of hardware failures, |
481 | after starting the monitor, either all messages sent to the port will |
640 | after starting the monitor, either all messages sent to the port will |
482 | arrive, or the monitoring action will be invoked after possible message |
641 | arrive, or the monitoring action will be invoked after possible message |
483 | loss has been detected. No messages will be lost "in between" (after |
642 | loss has been detected. No messages will be lost "in between" (after |
484 | the first lost message no further messages will be received by the |
643 | the first lost message no further messages will be received by the |
485 | port). After the monitoring action was invoked, further messages might get |
644 | port). After the monitoring action was invoked, further messages might get |
486 | delivered again. |
645 | delivered again. |
487 | |
646 | |
488 | Note that monitoring-actions are one-shot: once messages are lost (and a |
647 | Inter-host-connection timeouts and monitoring depend on the transport |
489 | monitoring alert was raised), they are removed and will not trigger again. |
648 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
|
|
649 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
|
|
650 | non-idle connection, and usually around two hours for idle connections). |
490 | |
651 | |
491 | In the first form (callback), the callback is simply called with any |
652 | This means that monitoring is good for program errors and cleaning up |
492 | number of C<@reason> elements (no @reason means that the port was deleted |
653 | stuff eventually, but they are no replacement for a timeout when you need |
493 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
654 | to ensure some maximum latency. |
494 | C<eval> if unsure. |
|
|
495 | |
|
|
496 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
497 | will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on |
|
|
498 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
499 | port is killed with the same reason. |
|
|
500 | |
|
|
501 | The third form (kill self) is the same as the second form, except that |
|
|
502 | C<$rvport> defaults to C<$SELF>. |
|
|
503 | |
|
|
504 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
505 | C<snd>. |
|
|
506 | |
|
|
507 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
508 | a local port (or callback). The reason is that kill messages might get |
|
|
509 | lost, just like any other message. Another less obvious reason is that |
|
|
510 | even monitoring requests can get lost (for exmaple, when the connection |
|
|
511 | to the other node goes down permanently). When monitoring a port locally |
|
|
512 | these problems do not exist. |
|
|
513 | |
655 | |
514 | Example: call a given callback when C<$port> is killed. |
656 | Example: call a given callback when C<$port> is killed. |
515 | |
657 | |
516 | mon $port, sub { warn "port died because of <@_>\n" }; |
658 | mon $port, sub { warn "port died because of <@_>\n" }; |
517 | |
659 | |
… | |
… | |
524 | mon $port, $self => "restart"; |
666 | mon $port, $self => "restart"; |
525 | |
667 | |
526 | =cut |
668 | =cut |
527 | |
669 | |
528 | sub mon { |
670 | sub mon { |
529 | my ($noderef, $port) = split /#/, shift, 2; |
671 | my ($nodeid, $port) = split /#/, shift, 2; |
530 | |
672 | |
531 | my $node = $NODE{$noderef} || add_node $noderef; |
673 | my $node = $NODE{$nodeid} || add_node $nodeid; |
532 | |
674 | |
533 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
675 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
534 | |
676 | |
535 | unless (ref $cb) { |
677 | unless (ref $cb) { |
536 | if (@_) { |
678 | if (@_) { |
… | |
… | |
545 | } |
687 | } |
546 | |
688 | |
547 | $node->monitor ($port, $cb); |
689 | $node->monitor ($port, $cb); |
548 | |
690 | |
549 | defined wantarray |
691 | defined wantarray |
550 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
692 | and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) }) |
551 | } |
693 | } |
552 | |
694 | |
553 | =item $guard = mon_guard $port, $ref, $ref... |
695 | =item $guard = mon_guard $port, $ref, $ref... |
554 | |
696 | |
555 | Monitors the given C<$port> and keeps the passed references. When the port |
697 | Monitors the given C<$port> and keeps the passed references. When the port |
… | |
… | |
578 | |
720 | |
579 | =item kil $port[, @reason] |
721 | =item kil $port[, @reason] |
580 | |
722 | |
581 | Kill the specified port with the given C<@reason>. |
723 | Kill the specified port with the given C<@reason>. |
582 | |
724 | |
583 | If no C<@reason> is specified, then the port is killed "normally" (ports |
725 | If no C<@reason> is specified, then the port is killed "normally" - |
584 | monitoring other ports will not necessarily die because a port dies |
726 | monitor callback will be invoked, but the kil will not cause linked ports |
585 | "normally"). |
727 | (C<mon $mport, $lport> form) to get killed. |
586 | |
728 | |
587 | Otherwise, linked ports get killed with the same reason (second form of |
729 | If a C<@reason> is specified, then linked ports (C<mon $mport, $lport> |
588 | C<mon>, see above). |
730 | form) get killed with the same reason. |
589 | |
731 | |
590 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
732 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
591 | will be reported as reason C<< die => $@ >>. |
733 | will be reported as reason C<< die => $@ >>. |
592 | |
734 | |
593 | Transport/communication errors are reported as C<< transport_error => |
735 | Transport/communication errors are reported as C<< transport_error => |
594 | $message >>. |
736 | $message >>. |
595 | |
737 | |
596 | =cut |
738 | Common idioms: |
|
|
739 | |
|
|
740 | # silently remove yourself, do not kill linked ports |
|
|
741 | kil $SELF; |
|
|
742 | |
|
|
743 | # report a failure in some detail |
|
|
744 | kil $SELF, failure_mode_1 => "it failed with too high temperature"; |
|
|
745 | |
|
|
746 | # do not waste much time with killing, just die when something goes wrong |
|
|
747 | open my $fh, "<file" |
|
|
748 | or die "file: $!"; |
597 | |
749 | |
598 | =item $port = spawn $node, $initfunc[, @initdata] |
750 | =item $port = spawn $node, $initfunc[, @initdata] |
599 | |
751 | |
600 | Creates a port on the node C<$node> (which can also be a port ID, in which |
752 | Creates a port on the node C<$node> (which can also be a port ID, in which |
601 | case it's the node where that port resides). |
753 | case it's the node where that port resides). |
… | |
… | |
612 | the package, then the package above the package and so on (e.g. |
764 | the package, then the package above the package and so on (e.g. |
613 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
765 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
614 | exists or it runs out of package names. |
766 | exists or it runs out of package names. |
615 | |
767 | |
616 | The init function is then called with the newly-created port as context |
768 | The init function is then called with the newly-created port as context |
617 | object (C<$SELF>) and the C<@initdata> values as arguments. |
769 | object (C<$SELF>) and the C<@initdata> values as arguments. It I<must> |
|
|
770 | call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise |
|
|
771 | the port might not get created. |
618 | |
772 | |
619 | A common idiom is to pass a local port, immediately monitor the spawned |
773 | A common idiom is to pass a local port, immediately monitor the spawned |
620 | port, and in the remote init function, immediately monitor the passed |
774 | port, and in the remote init function, immediately monitor the passed |
621 | local port. This two-way monitoring ensures that both ports get cleaned up |
775 | local port. This two-way monitoring ensures that both ports get cleaned up |
622 | when there is a problem. |
776 | when there is a problem. |
623 | |
777 | |
|
|
778 | C<spawn> guarantees that the C<$initfunc> has no visible effects on the |
|
|
779 | caller before C<spawn> returns (by delaying invocation when spawn is |
|
|
780 | called for the local node). |
|
|
781 | |
624 | Example: spawn a chat server port on C<$othernode>. |
782 | Example: spawn a chat server port on C<$othernode>. |
625 | |
783 | |
626 | # this node, executed from within a port context: |
784 | # this node, executed from within a port context: |
627 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
785 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
628 | mon $server; |
786 | mon $server; |
… | |
… | |
642 | |
800 | |
643 | sub _spawn { |
801 | sub _spawn { |
644 | my $port = shift; |
802 | my $port = shift; |
645 | my $init = shift; |
803 | my $init = shift; |
646 | |
804 | |
|
|
805 | # rcv will create the actual port |
647 | local $SELF = "$NODE#$port"; |
806 | local $SELF = "$NODE#$port"; |
648 | eval { |
807 | eval { |
649 | &{ load_func $init } |
808 | &{ load_func $init } |
650 | }; |
809 | }; |
651 | _self_die if $@; |
810 | _self_die if $@; |
652 | } |
811 | } |
653 | |
812 | |
654 | sub spawn(@) { |
813 | sub spawn(@) { |
655 | my ($noderef, undef) = split /#/, shift, 2; |
814 | my ($nodeid, undef) = split /#/, shift, 2; |
656 | |
815 | |
657 | my $id = "$RUNIQ." . $ID++; |
816 | my $id = $RUNIQ . ++$ID; |
658 | |
817 | |
659 | $_[0] =~ /::/ |
818 | $_[0] =~ /::/ |
660 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
819 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
661 | |
820 | |
662 | snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_; |
821 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
663 | |
822 | |
664 | "$noderef#$id" |
823 | "$nodeid#$id" |
665 | } |
824 | } |
|
|
825 | |
666 | |
826 | |
667 | =item after $timeout, @msg |
827 | =item after $timeout, @msg |
668 | |
828 | |
669 | =item after $timeout, $callback |
829 | =item after $timeout, $callback |
670 | |
830 | |
… | |
… | |
686 | ? $action[0]() |
846 | ? $action[0]() |
687 | : snd @action; |
847 | : snd @action; |
688 | }; |
848 | }; |
689 | } |
849 | } |
690 | |
850 | |
|
|
851 | #=item $cb2 = timeout $seconds, $cb[, @args] |
|
|
852 | |
|
|
853 | =item cal $port, @msg, $callback[, $timeout] |
|
|
854 | |
|
|
855 | A simple form of RPC - sends a message to the given C<$port> with the |
|
|
856 | given contents (C<@msg>), but adds a reply port to the message. |
|
|
857 | |
|
|
858 | The reply port is created temporarily just for the purpose of receiving |
|
|
859 | the reply, and will be C<kil>ed when no longer needed. |
|
|
860 | |
|
|
861 | A reply message sent to the port is passed to the C<$callback> as-is. |
|
|
862 | |
|
|
863 | If an optional time-out (in seconds) is given and it is not C<undef>, |
|
|
864 | then the callback will be called without any arguments after the time-out |
|
|
865 | elapsed and the port is C<kil>ed. |
|
|
866 | |
|
|
867 | If no time-out is given (or it is C<undef>), then the local port will |
|
|
868 | monitor the remote port instead, so it eventually gets cleaned-up. |
|
|
869 | |
|
|
870 | Currently this function returns the temporary port, but this "feature" |
|
|
871 | might go in future versions unless you can make a convincing case that |
|
|
872 | this is indeed useful for something. |
|
|
873 | |
|
|
874 | =cut |
|
|
875 | |
|
|
876 | sub cal(@) { |
|
|
877 | my $timeout = ref $_[-1] ? undef : pop; |
|
|
878 | my $cb = pop; |
|
|
879 | |
|
|
880 | my $port = port { |
|
|
881 | undef $timeout; |
|
|
882 | kil $SELF; |
|
|
883 | &$cb; |
|
|
884 | }; |
|
|
885 | |
|
|
886 | if (defined $timeout) { |
|
|
887 | $timeout = AE::timer $timeout, 0, sub { |
|
|
888 | undef $timeout; |
|
|
889 | kil $port; |
|
|
890 | $cb->(); |
|
|
891 | }; |
|
|
892 | } else { |
|
|
893 | mon $_[0], sub { |
|
|
894 | kil $port; |
|
|
895 | $cb->(); |
|
|
896 | }; |
|
|
897 | } |
|
|
898 | |
|
|
899 | push @_, $port; |
|
|
900 | &snd; |
|
|
901 | |
|
|
902 | $port |
|
|
903 | } |
|
|
904 | |
|
|
905 | =back |
|
|
906 | |
|
|
907 | =head1 DISTRIBUTED DATABASE |
|
|
908 | |
|
|
909 | AnyEvent::MP comes with a simple distributed database. The database will |
|
|
910 | be mirrored asynchronously on all global nodes. Other nodes bind to one |
|
|
911 | of the global nodes for their needs. Every node has a "local database" |
|
|
912 | which contains all the values that are set locally. All local databases |
|
|
913 | are merged together to form the global database, which can be queried. |
|
|
914 | |
|
|
915 | The database structure is that of a two-level hash - the database hash |
|
|
916 | contains hashes which contain values, similarly to a perl hash of hashes, |
|
|
917 | i.e.: |
|
|
918 | |
|
|
919 | $DATABASE{$family}{$subkey} = $value |
|
|
920 | |
|
|
921 | The top level hash key is called "family", and the second-level hash key |
|
|
922 | is called "subkey" or simply "key". |
|
|
923 | |
|
|
924 | The family must be alphanumeric, i.e. start with a letter and consist |
|
|
925 | of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>, |
|
|
926 | pretty much like Perl module names. |
|
|
927 | |
|
|
928 | As the family namespace is global, it is recommended to prefix family names |
|
|
929 | with the name of the application or module using it. |
|
|
930 | |
|
|
931 | The subkeys must be non-empty strings, with no further restrictions. |
|
|
932 | |
|
|
933 | The values should preferably be strings, but other perl scalars should |
|
|
934 | work as well (such as C<undef>, arrays and hashes). |
|
|
935 | |
|
|
936 | Every database entry is owned by one node - adding the same family/subkey |
|
|
937 | combination on multiple nodes will not cause discomfort for AnyEvent::MP, |
|
|
938 | but the result might be nondeterministic, i.e. the key might have |
|
|
939 | different values on different nodes. |
|
|
940 | |
|
|
941 | Different subkeys in the same family can be owned by different nodes |
|
|
942 | without problems, and in fact, this is the common method to create worker |
|
|
943 | pools. For example, a worker port for image scaling might do this: |
|
|
944 | |
|
|
945 | db_set my_image_scalers => $port; |
|
|
946 | |
|
|
947 | And clients looking for an image scaler will want to get the |
|
|
948 | C<my_image_scalers> keys from time to time: |
|
|
949 | |
|
|
950 | db_keys my_image_scalers => sub { |
|
|
951 | @ports = @{ $_[0] }; |
|
|
952 | }; |
|
|
953 | |
|
|
954 | Or better yet, they want to monitor the database family, so they always |
|
|
955 | have a reasonable up-to-date copy: |
|
|
956 | |
|
|
957 | db_mon my_image_scalers => sub { |
|
|
958 | @ports = keys %{ $_[0] }; |
|
|
959 | }; |
|
|
960 | |
|
|
961 | In general, you can set or delete single subkeys, but query and monitor |
|
|
962 | whole families only. |
|
|
963 | |
|
|
964 | If you feel the need to monitor or query a single subkey, try giving it |
|
|
965 | it's own family. |
|
|
966 | |
|
|
967 | =over |
|
|
968 | |
|
|
969 | =item db_set $family => $subkey [=> $value] |
|
|
970 | |
|
|
971 | Sets (or replaces) a key to the database - if C<$value> is omitted, |
|
|
972 | C<undef> is used instead. |
|
|
973 | |
|
|
974 | =item db_del $family => $subkey... |
|
|
975 | |
|
|
976 | Deletes one or more subkeys from the database family. |
|
|
977 | |
|
|
978 | =item $guard = db_reg $family => $subkey [=> $value] |
|
|
979 | |
|
|
980 | Sets the key on the database and returns a guard. When the guard is |
|
|
981 | destroyed, the key is deleted from the database. If C<$value> is missing, |
|
|
982 | then C<undef> is used. |
|
|
983 | |
|
|
984 | =item db_family $family => $cb->(\%familyhash) |
|
|
985 | |
|
|
986 | Queries the named database C<$family> and call the callback with the |
|
|
987 | family represented as a hash. You can keep and freely modify the hash. |
|
|
988 | |
|
|
989 | =item db_keys $family => $cb->(\@keys) |
|
|
990 | |
|
|
991 | Same as C<db_family>, except it only queries the family I<subkeys> and passes |
|
|
992 | them as array reference to the callback. |
|
|
993 | |
|
|
994 | =item db_values $family => $cb->(\@values) |
|
|
995 | |
|
|
996 | Same as C<db_family>, except it only queries the family I<values> and passes them |
|
|
997 | as array reference to the callback. |
|
|
998 | |
|
|
999 | =item $guard = db_mon $family => $cb->($familyhash, \@added, \@changed, \@deleted) |
|
|
1000 | |
|
|
1001 | Creates a monitor on the given database family. Each time a key is set |
|
|
1002 | or or is deleted the callback is called with a hash containing the |
|
|
1003 | database family and three lists of added, changed and deleted subkeys, |
|
|
1004 | respectively. If no keys have changed then the array reference might be |
|
|
1005 | C<undef> or even missing. |
|
|
1006 | |
|
|
1007 | If not called in void context, a guard object is returned that, when |
|
|
1008 | destroyed, stops the monitor. |
|
|
1009 | |
|
|
1010 | The family hash reference and the key arrays belong to AnyEvent::MP and |
|
|
1011 | B<must not be modified or stored> by the callback. When in doubt, make a |
|
|
1012 | copy. |
|
|
1013 | |
|
|
1014 | As soon as possible after the monitoring starts, the callback will be |
|
|
1015 | called with the intiial contents of the family, even if it is empty, |
|
|
1016 | i.e. there will always be a timely call to the callback with the current |
|
|
1017 | contents. |
|
|
1018 | |
|
|
1019 | It is possible that the callback is called with a change event even though |
|
|
1020 | the subkey is already present and the value has not changed. |
|
|
1021 | |
|
|
1022 | The monitoring stops when the guard object is destroyed. |
|
|
1023 | |
|
|
1024 | Example: on every change to the family "mygroup", print out all keys. |
|
|
1025 | |
|
|
1026 | my $guard = db_mon mygroup => sub { |
|
|
1027 | my ($family, $a, $c, $d) = @_; |
|
|
1028 | print "mygroup members: ", (join " ", keys %$family), "\n"; |
|
|
1029 | }; |
|
|
1030 | |
|
|
1031 | Exmaple: wait until the family "My::Module::workers" is non-empty. |
|
|
1032 | |
|
|
1033 | my $guard; $guard = db_mon My::Module::workers => sub { |
|
|
1034 | my ($family, $a, $c, $d) = @_; |
|
|
1035 | return unless %$family; |
|
|
1036 | undef $guard; |
|
|
1037 | print "My::Module::workers now nonempty\n"; |
|
|
1038 | }; |
|
|
1039 | |
|
|
1040 | Example: print all changes to the family "AnyRvent::Fantasy::Module". |
|
|
1041 | |
|
|
1042 | my $guard = db_mon AnyRvent::Fantasy::Module => sub { |
|
|
1043 | my ($family, $a, $c, $d) = @_; |
|
|
1044 | |
|
|
1045 | print "+$_=$family->{$_}\n" for @$a; |
|
|
1046 | print "*$_=$family->{$_}\n" for @$c; |
|
|
1047 | print "-$_=$family->{$_}\n" for @$d; |
|
|
1048 | }; |
|
|
1049 | |
|
|
1050 | =cut |
|
|
1051 | |
691 | =back |
1052 | =back |
692 | |
1053 | |
693 | =head1 AnyEvent::MP vs. Distributed Erlang |
1054 | =head1 AnyEvent::MP vs. Distributed Erlang |
694 | |
1055 | |
695 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
1056 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
696 | == aemp node, Erlang process == aemp port), so many of the documents and |
1057 | == aemp node, Erlang process == aemp port), so many of the documents and |
697 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
1058 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
698 | sample: |
1059 | sample: |
699 | |
1060 | |
700 | http://www.Erlang.se/doc/programming_rules.shtml |
1061 | http://www.erlang.se/doc/programming_rules.shtml |
701 | http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
1062 | http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
702 | http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6 |
1063 | http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6 |
703 | http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
1064 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
704 | |
1065 | |
705 | Despite the similarities, there are also some important differences: |
1066 | Despite the similarities, there are also some important differences: |
706 | |
1067 | |
707 | =over 4 |
1068 | =over 4 |
708 | |
1069 | |
709 | =item * Node IDs are arbitrary strings in AEMP. |
1070 | =item * Node IDs are arbitrary strings in AEMP. |
710 | |
1071 | |
711 | Erlang relies on special naming and DNS to work everywhere in the same |
1072 | Erlang relies on special naming and DNS to work everywhere in the same |
712 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
1073 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
713 | configuraiton or DNS), but will otherwise discover other odes itself. |
1074 | configuration or DNS), and possibly the addresses of some seed nodes, but |
|
|
1075 | will otherwise discover other nodes (and their IDs) itself. |
714 | |
1076 | |
715 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
1077 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
716 | uses "local ports are like remote ports". |
1078 | uses "local ports are like remote ports". |
717 | |
1079 | |
718 | The failure modes for local ports are quite different (runtime errors |
1080 | The failure modes for local ports are quite different (runtime errors |
… | |
… | |
727 | ports being the special case/exception, where transport errors cannot |
1089 | ports being the special case/exception, where transport errors cannot |
728 | occur. |
1090 | occur. |
729 | |
1091 | |
730 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
1092 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
731 | |
1093 | |
732 | Erlang uses processes that selectively receive messages, and therefore |
1094 | Erlang uses processes that selectively receive messages out of order, and |
733 | needs a queue. AEMP is event based, queuing messages would serve no |
1095 | therefore needs a queue. AEMP is event based, queuing messages would serve |
734 | useful purpose. For the same reason the pattern-matching abilities of |
1096 | no useful purpose. For the same reason the pattern-matching abilities |
735 | AnyEvent::MP are more limited, as there is little need to be able to |
1097 | of AnyEvent::MP are more limited, as there is little need to be able to |
736 | filter messages without dequeing them. |
1098 | filter messages without dequeuing them. |
737 | |
1099 | |
738 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
1100 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
|
|
1101 | being event-based, while Erlang is process-based. |
|
|
1102 | |
|
|
1103 | You cna have a look at L<Coro::MP> for a more Erlang-like process model on |
|
|
1104 | top of AEMP and Coro threads. |
739 | |
1105 | |
740 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
1106 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
741 | |
1107 | |
742 | Sending messages in Erlang is synchronous and blocks the process (and |
1108 | Sending messages in Erlang is synchronous and blocks the process until |
|
|
1109 | a conenction has been established and the message sent (and so does not |
743 | so does not need a queue that can overflow). AEMP sends are immediate, |
1110 | need a queue that can overflow). AEMP sends return immediately, connection |
744 | connection establishment is handled in the background. |
1111 | establishment is handled in the background. |
745 | |
1112 | |
746 | =item * Erlang suffers from silent message loss, AEMP does not. |
1113 | =item * Erlang suffers from silent message loss, AEMP does not. |
747 | |
1114 | |
748 | Erlang makes few guarantees on messages delivery - messages can get lost |
1115 | Erlang implements few guarantees on messages delivery - messages can get |
749 | without any of the processes realising it (i.e. you send messages a, b, |
1116 | lost without any of the processes realising it (i.e. you send messages a, |
750 | and c, and the other side only receives messages a and c). |
1117 | b, and c, and the other side only receives messages a and c). |
751 | |
1118 | |
752 | AEMP guarantees correct ordering, and the guarantee that after one message |
1119 | AEMP guarantees (modulo hardware errors) correct ordering, and the |
753 | is lost, all following ones sent to the same port are lost as well, until |
1120 | guarantee that after one message is lost, all following ones sent to the |
754 | monitoring raises an error, so there are no silent "holes" in the message |
1121 | same port are lost as well, until monitoring raises an error, so there are |
755 | sequence. |
1122 | no silent "holes" in the message sequence. |
|
|
1123 | |
|
|
1124 | If you want your software to be very reliable, you have to cope with |
|
|
1125 | corrupted and even out-of-order messages in both Erlang and AEMP. AEMP |
|
|
1126 | simply tries to work better in common error cases, such as when a network |
|
|
1127 | link goes down. |
756 | |
1128 | |
757 | =item * Erlang can send messages to the wrong port, AEMP does not. |
1129 | =item * Erlang can send messages to the wrong port, AEMP does not. |
758 | |
1130 | |
759 | In Erlang it is quite likely that a node that restarts reuses a process ID |
1131 | In Erlang it is quite likely that a node that restarts reuses an Erlang |
760 | known to other nodes for a completely different process, causing messages |
1132 | process ID known to other nodes for a completely different process, |
761 | destined for that process to end up in an unrelated process. |
1133 | causing messages destined for that process to end up in an unrelated |
|
|
1134 | process. |
762 | |
1135 | |
763 | AEMP never reuses port IDs, so old messages or old port IDs floating |
1136 | AEMP does not reuse port IDs, so old messages or old port IDs floating |
764 | around in the network will not be sent to an unrelated port. |
1137 | around in the network will not be sent to an unrelated port. |
765 | |
1138 | |
766 | =item * Erlang uses unprotected connections, AEMP uses secure |
1139 | =item * Erlang uses unprotected connections, AEMP uses secure |
767 | authentication and can use TLS. |
1140 | authentication and can use TLS. |
768 | |
1141 | |
… | |
… | |
771 | |
1144 | |
772 | =item * The AEMP protocol is optimised for both text-based and binary |
1145 | =item * The AEMP protocol is optimised for both text-based and binary |
773 | communications. |
1146 | communications. |
774 | |
1147 | |
775 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
1148 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
776 | language independent text-only protocols (good for debugging) and binary, |
1149 | language independent text-only protocols (good for debugging), and binary, |
777 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
1150 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
778 | used, the protocol is actually completely text-based. |
1151 | used, the protocol is actually completely text-based. |
779 | |
1152 | |
780 | It has also been carefully designed to be implementable in other languages |
1153 | It has also been carefully designed to be implementable in other languages |
781 | with a minimum of work while gracefully degrading functionality to make the |
1154 | with a minimum of work while gracefully degrading functionality to make the |
782 | protocol simple. |
1155 | protocol simple. |
783 | |
1156 | |
784 | =item * AEMP has more flexible monitoring options than Erlang. |
1157 | =item * AEMP has more flexible monitoring options than Erlang. |
785 | |
1158 | |
786 | In Erlang, you can chose to receive I<all> exit signals as messages |
1159 | In Erlang, you can chose to receive I<all> exit signals as messages or |
787 | or I<none>, there is no in-between, so monitoring single processes is |
1160 | I<none>, there is no in-between, so monitoring single Erlang processes is |
788 | difficult to implement. Monitoring in AEMP is more flexible than in |
1161 | difficult to implement. |
789 | Erlang, as one can choose between automatic kill, exit message or callback |
1162 | |
790 | on a per-process basis. |
1163 | Monitoring in AEMP is more flexible than in Erlang, as one can choose |
|
|
1164 | between automatic kill, exit message or callback on a per-port basis. |
791 | |
1165 | |
792 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
1166 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
793 | |
1167 | |
794 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
1168 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
795 | same way as linking is (except linking is unreliable in Erlang). |
1169 | same way as linking is (except linking is unreliable in Erlang). |
… | |
… | |
817 | overhead, as well as having to keep a proxy object everywhere. |
1191 | overhead, as well as having to keep a proxy object everywhere. |
818 | |
1192 | |
819 | Strings can easily be printed, easily serialised etc. and need no special |
1193 | Strings can easily be printed, easily serialised etc. and need no special |
820 | procedures to be "valid". |
1194 | procedures to be "valid". |
821 | |
1195 | |
822 | And as a result, a miniport consists of a single closure stored in a |
1196 | And as a result, a port with just a default receiver consists of a single |
823 | global hash - it can't become much cheaper. |
1197 | code reference stored in a global hash - it can't become much cheaper. |
824 | |
1198 | |
825 | =item Why favour JSON, why not a real serialising format such as Storable? |
1199 | =item Why favour JSON, why not a real serialising format such as Storable? |
826 | |
1200 | |
827 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
1201 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
828 | format, but currently there is no way to make a node use Storable by |
1202 | format, but currently there is no way to make a node use Storable by |
… | |
… | |
844 | |
1218 | |
845 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1219 | L<AnyEvent::MP::Intro> - a gentle introduction. |
846 | |
1220 | |
847 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
1221 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
848 | |
1222 | |
849 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
1223 | L<AnyEvent::MP::Global> - network maintenance and port groups, to find |
850 | your applications. |
1224 | your applications. |
|
|
1225 | |
|
|
1226 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
|
|
1227 | |
|
|
1228 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
|
|
1229 | all nodes. |
851 | |
1230 | |
852 | L<AnyEvent>. |
1231 | L<AnyEvent>. |
853 | |
1232 | |
854 | =head1 AUTHOR |
1233 | =head1 AUTHOR |
855 | |
1234 | |