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; |
24 | |
23 | |
25 | # creating/using ports, the simple way |
24 | # creating/using ports, the simple way |
26 | my $simple_port = port { my @msg = @_; 0 }; |
25 | my $simple_port = port { my @msg = @_ }; |
27 | |
26 | |
28 | # creating/using ports, tagged message matching |
27 | # creating/using ports, tagged message matching |
29 | my $port = port; |
28 | my $port = port; |
30 | rcv $port, ping => sub { snd $_[0], "pong"; 0 }; |
29 | rcv $port, ping => sub { snd $_[0], "pong" }; |
31 | rcv $port, pong => sub { warn "pong received\n"; 0 }; |
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 $localport, $cb->(@msg) # callback is invoked on death |
38 | mon $port, $otherport # kill otherport on abnormal death |
41 | mon $localport, $otherport # kill otherport on abnormal death |
39 | mon $port, $otherport, @msg # send message on death |
42 | mon $localport, $otherport, @msg # send message on death |
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43 | |
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44 | # temporarily execute code in port context |
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45 | peval $port, sub { die "kill the port!" }; |
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46 | |
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47 | # execute callbacks in $SELF port context |
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48 | my $timer = AE::timer 1, 0, psub { |
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49 | die "kill the port, delayed"; |
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50 | }; |
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 | |
… | |
… | |
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 |
146 | ); |
202 | ); |
147 | |
203 | |
148 | our $SELF; |
204 | our $SELF; |
149 | |
205 | |
150 | sub _self_die() { |
206 | sub _self_die() { |
… | |
… | |
161 | |
217 | |
162 | =item $nodeid = node_of $port |
218 | =item $nodeid = node_of $port |
163 | |
219 | |
164 | Extracts and returns the node ID from a port ID or a node ID. |
220 | Extracts and returns the node ID from a port ID or a node ID. |
165 | |
221 | |
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222 | =item configure $profile, key => value... |
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223 | |
166 | =item configure key => value... |
224 | =item configure key => value... |
167 | |
225 | |
168 | Before a node can talk to other nodes on the network (i.e. enter |
226 | 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 |
227 | "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 |
228 | 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. |
229 | some other nodes in the network to discover other nodes. |
172 | |
230 | |
173 | This function configures a node - it must be called exactly once (or |
231 | This function configures a node - it must be called exactly once (or |
174 | never) before calling other AnyEvent::MP functions. |
232 | never) before calling other AnyEvent::MP functions. |
175 | |
233 | |
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234 | The key/value pairs are basically the same ones as documented for the |
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235 | F<aemp> command line utility (sans the set/del prefix), with two additions: |
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236 | |
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237 | =over 4 |
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238 | |
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239 | =item norc => $boolean (default false) |
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240 | |
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241 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
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242 | be consulted - all configuraiton options must be specified in the |
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243 | C<configure> call. |
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244 | |
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245 | =item force => $boolean (default false) |
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246 | |
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247 | IF true, then the values specified in the C<configure> will take |
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248 | precedence over any values configured via the rc file. The default is for |
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249 | the rc file to override any options specified in the program. |
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250 | |
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251 | =back |
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252 | |
176 | =over 4 |
253 | =over 4 |
177 | |
254 | |
178 | =item step 1, gathering configuration from profiles |
255 | =item step 1, gathering configuration from profiles |
179 | |
256 | |
180 | The function first looks up a profile in the aemp configuration (see the |
257 | 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 |
258 | 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 |
259 | named C<profile> parameter or can simply be the first parameter). If it is |
183 | -n>) will be used as profile name. |
260 | missing, then the nodename (F<uname -n>) will be used as profile name. |
184 | |
261 | |
185 | The profile data is then gathered as follows: |
262 | The profile data is then gathered as follows: |
186 | |
263 | |
187 | First, all remaining key => value pairs (all of which are conviniently |
264 | First, all remaining key => value pairs (all of which are conveniently |
188 | undocumented at the moment) will be interpreted as configuration |
265 | undocumented at the moment) will be interpreted as configuration |
189 | data. Then they will be overwritten by any values specified in the global |
266 | 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 |
267 | default configuration (see the F<aemp> utility), then the chain of |
191 | profiles chosen by the profile name (and any C<parent> attributes). |
268 | profiles chosen by the profile name (and any C<parent> attributes). |
192 | |
269 | |
193 | That means that the values specified in the profile have highest priority |
270 | That means that the values specified in the profile have highest priority |
194 | and the values specified directly via C<configure> have lowest priority, |
271 | and the values specified directly via C<configure> have lowest priority, |
195 | and can only be used to specify defaults. |
272 | and can only be used to specify defaults. |
196 | |
273 | |
197 | If the profile specifies a node ID, then this will become the node ID of |
274 | 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 |
275 | 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. |
276 | a slash (C</>) attached. |
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277 | |
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278 | If the node ID (or profile name) ends with a slash (C</>), then a random |
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279 | string is appended to make it unique. |
200 | |
280 | |
201 | =item step 2, bind listener sockets |
281 | =item step 2, bind listener sockets |
202 | |
282 | |
203 | The next step is to look up the binds in the profile, followed by binding |
283 | 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 |
284 | aemp protocol listeners on all binds specified (it is possible and valid |
… | |
… | |
210 | used, meaning the node will bind on a dynamically-assigned port on every |
290 | used, meaning the node will bind on a dynamically-assigned port on every |
211 | local IP address it finds. |
291 | local IP address it finds. |
212 | |
292 | |
213 | =item step 3, connect to seed nodes |
293 | =item step 3, connect to seed nodes |
214 | |
294 | |
215 | As the last step, the seeds list from the profile is passed to the |
295 | 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 |
296 | L<AnyEvent::MP::Global> module, which will then use it to keep |
217 | connectivity with at least one node at any point in time. |
297 | connectivity with at least one node at any point in time. |
218 | |
298 | |
219 | =back |
299 | =back |
220 | |
300 | |
221 | Example: become a distributed node using the locla node name as profile. |
301 | 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. |
302 | This should be the most common form of invocation for "daemon"-type nodes. |
223 | |
303 | |
224 | configure |
304 | configure |
225 | |
305 | |
226 | Example: become an anonymous node. This form is often used for commandline |
306 | Example: become an anonymous node. This form is often used for commandline |
227 | clients. |
307 | clients. |
228 | |
308 | |
229 | configure nodeid => "anon/"; |
309 | configure nodeid => "anon/"; |
230 | |
310 | |
231 | Example: configure a node using a profile called seed, which si suitable |
311 | 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, |
312 | for a seed node as it binds on all local addresses on a fixed port (4040, |
233 | customary for aemp). |
313 | customary for aemp). |
234 | |
314 | |
235 | # use the aemp commandline utility |
315 | # use the aemp commandline utility |
236 | # aemp profile seed setnodeid anon/ setbinds '*:4040' |
316 | # aemp profile seed binds '*:4040' |
237 | |
317 | |
238 | # then use it |
318 | # then use it |
239 | configure profile => "seed"; |
319 | configure profile => "seed"; |
240 | |
320 | |
241 | # or simply use aemp from the shell again: |
321 | # or simply use aemp from the shell again: |
… | |
… | |
311 | sub _kilme { |
391 | sub _kilme { |
312 | die "received message on port without callback"; |
392 | die "received message on port without callback"; |
313 | } |
393 | } |
314 | |
394 | |
315 | sub port(;&) { |
395 | sub port(;&) { |
316 | my $id = "$UNIQ." . $ID++; |
396 | my $id = $UNIQ . ++$ID; |
317 | my $port = "$NODE#$id"; |
397 | my $port = "$NODE#$id"; |
318 | |
398 | |
319 | rcv $port, shift || \&_kilme; |
399 | rcv $port, shift || \&_kilme; |
320 | |
400 | |
321 | $port |
401 | $port |
… | |
… | |
360 | msg1 => sub { ... }, |
440 | msg1 => sub { ... }, |
361 | ... |
441 | ... |
362 | ; |
442 | ; |
363 | |
443 | |
364 | Example: temporarily register a rcv callback for a tag matching some port |
444 | 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. |
445 | (e.g. for an rpc reply) and unregister it after a message was received. |
366 | |
446 | |
367 | rcv $port, $otherport => sub { |
447 | rcv $port, $otherport => sub { |
368 | my @reply = @_; |
448 | my @reply = @_; |
369 | |
449 | |
370 | rcv $SELF, $otherport; |
450 | rcv $SELF, $otherport; |
… | |
… | |
372 | |
452 | |
373 | =cut |
453 | =cut |
374 | |
454 | |
375 | sub rcv($@) { |
455 | sub rcv($@) { |
376 | my $port = shift; |
456 | my $port = shift; |
377 | my ($noderef, $portid) = split /#/, $port, 2; |
457 | my ($nodeid, $portid) = split /#/, $port, 2; |
378 | |
458 | |
379 | $NODE{$noderef} == $NODE{""} |
459 | $NODE{$nodeid} == $NODE{""} |
380 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
460 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
381 | |
461 | |
382 | while (@_) { |
462 | while (@_) { |
383 | if (ref $_[0]) { |
463 | if (ref $_[0]) { |
384 | if (my $self = $PORT_DATA{$portid}) { |
464 | if (my $self = $PORT_DATA{$portid}) { |
385 | "AnyEvent::MP::Port" eq ref $self |
465 | "AnyEvent::MP::Port" eq ref $self |
386 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
466 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
387 | |
467 | |
388 | $self->[2] = shift; |
468 | $self->[0] = shift; |
389 | } else { |
469 | } else { |
390 | my $cb = shift; |
470 | my $cb = shift; |
391 | $PORT{$portid} = sub { |
471 | $PORT{$portid} = sub { |
392 | local $SELF = $port; |
472 | local $SELF = $port; |
393 | eval { &$cb }; _self_die if $@; |
473 | eval { &$cb }; _self_die if $@; |
394 | }; |
474 | }; |
395 | } |
475 | } |
396 | } elsif (defined $_[0]) { |
476 | } elsif (defined $_[0]) { |
397 | my $self = $PORT_DATA{$portid} ||= do { |
477 | my $self = $PORT_DATA{$portid} ||= do { |
398 | my $self = bless [$PORT{$port} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
478 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
399 | |
479 | |
400 | $PORT{$portid} = sub { |
480 | $PORT{$portid} = sub { |
401 | local $SELF = $port; |
481 | local $SELF = $port; |
402 | |
482 | |
403 | if (my $cb = $self->[1]{$_[0]}) { |
483 | if (my $cb = $self->[1]{$_[0]}) { |
… | |
… | |
425 | } |
505 | } |
426 | |
506 | |
427 | $port |
507 | $port |
428 | } |
508 | } |
429 | |
509 | |
|
|
510 | =item peval $port, $coderef[, @args] |
|
|
511 | |
|
|
512 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
|
|
513 | when the code throews an exception the C<$port> will be killed. |
|
|
514 | |
|
|
515 | Any remaining args will be passed to the callback. Any return values will |
|
|
516 | be returned to the caller. |
|
|
517 | |
|
|
518 | This is useful when you temporarily want to execute code in the context of |
|
|
519 | a port. |
|
|
520 | |
|
|
521 | Example: create a port and run some initialisation code in it's context. |
|
|
522 | |
|
|
523 | my $port = port { ... }; |
|
|
524 | |
|
|
525 | peval $port, sub { |
|
|
526 | init |
|
|
527 | or die "unable to init"; |
|
|
528 | }; |
|
|
529 | |
|
|
530 | =cut |
|
|
531 | |
|
|
532 | sub peval($$) { |
|
|
533 | local $SELF = shift; |
|
|
534 | my $cb = shift; |
|
|
535 | |
|
|
536 | if (wantarray) { |
|
|
537 | my @res = eval { &$cb }; |
|
|
538 | _self_die if $@; |
|
|
539 | @res |
|
|
540 | } else { |
|
|
541 | my $res = eval { &$cb }; |
|
|
542 | _self_die if $@; |
|
|
543 | $res |
|
|
544 | } |
|
|
545 | } |
|
|
546 | |
430 | =item $closure = psub { BLOCK } |
547 | =item $closure = psub { BLOCK } |
431 | |
548 | |
432 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
549 | 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> |
550 | 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. |
551 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
|
|
552 | |
|
|
553 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
|
|
554 | BLOCK }, @_ } >>. |
435 | |
555 | |
436 | This is useful when you register callbacks from C<rcv> callbacks: |
556 | This is useful when you register callbacks from C<rcv> callbacks: |
437 | |
557 | |
438 | rcv delayed_reply => sub { |
558 | rcv delayed_reply => sub { |
439 | my ($delay, @reply) = @_; |
559 | my ($delay, @reply) = @_; |
… | |
… | |
475 | |
595 | |
476 | Monitor the given port and do something when the port is killed or |
596 | Monitor the given port and do something when the port is killed or |
477 | messages to it were lost, and optionally return a guard that can be used |
597 | messages to it were lost, and optionally return a guard that can be used |
478 | to stop monitoring again. |
598 | to stop monitoring again. |
479 | |
599 | |
|
|
600 | In the first form (callback), the callback is simply called with any |
|
|
601 | number of C<@reason> elements (no @reason means that the port was deleted |
|
|
602 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
|
|
603 | C<eval> if unsure. |
|
|
604 | |
|
|
605 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
606 | will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on |
|
|
607 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
608 | port is killed with the same reason. |
|
|
609 | |
|
|
610 | The third form (kill self) is the same as the second form, except that |
|
|
611 | C<$rvport> defaults to C<$SELF>. |
|
|
612 | |
|
|
613 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
614 | C<snd>. |
|
|
615 | |
|
|
616 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
|
|
617 | alert was raised), they are removed and will not trigger again. |
|
|
618 | |
|
|
619 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
620 | a local port (or callback). The reason is that kill messages might get |
|
|
621 | lost, just like any other message. Another less obvious reason is that |
|
|
622 | even monitoring requests can get lost (for example, when the connection |
|
|
623 | to the other node goes down permanently). When monitoring a port locally |
|
|
624 | these problems do not exist. |
|
|
625 | |
480 | C<mon> effectively guarantees that, in the absence of hardware failures, |
626 | C<mon> effectively guarantees that, in the absence of hardware failures, |
481 | after starting the monitor, either all messages sent to the port will |
627 | after starting the monitor, either all messages sent to the port will |
482 | arrive, or the monitoring action will be invoked after possible message |
628 | arrive, or the monitoring action will be invoked after possible message |
483 | loss has been detected. No messages will be lost "in between" (after |
629 | 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 |
630 | the first lost message no further messages will be received by the |
485 | port). After the monitoring action was invoked, further messages might get |
631 | port). After the monitoring action was invoked, further messages might get |
486 | delivered again. |
632 | delivered again. |
487 | |
633 | |
488 | Note that monitoring-actions are one-shot: once messages are lost (and a |
634 | Inter-host-connection timeouts and monitoring depend on the transport |
489 | monitoring alert was raised), they are removed and will not trigger again. |
635 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
|
|
636 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
|
|
637 | non-idle connection, and usually around two hours for idle connections). |
490 | |
638 | |
491 | In the first form (callback), the callback is simply called with any |
639 | 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 |
640 | 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 |
641 | 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<$SELF>. |
|
|
503 | |
|
|
504 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
505 | C<snd>. |
|
|
506 | |
|
|
507 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
508 | a local port (or callback). The reason is that kill messages might get |
|
|
509 | lost, just like any other message. Another less obvious reason is that |
|
|
510 | even monitoring requests can get lost (for exmaple, when the connection |
|
|
511 | to the other node goes down permanently). When monitoring a port locally |
|
|
512 | these problems do not exist. |
|
|
513 | |
642 | |
514 | Example: call a given callback when C<$port> is killed. |
643 | Example: call a given callback when C<$port> is killed. |
515 | |
644 | |
516 | mon $port, sub { warn "port died because of <@_>\n" }; |
645 | mon $port, sub { warn "port died because of <@_>\n" }; |
517 | |
646 | |
… | |
… | |
524 | mon $port, $self => "restart"; |
653 | mon $port, $self => "restart"; |
525 | |
654 | |
526 | =cut |
655 | =cut |
527 | |
656 | |
528 | sub mon { |
657 | sub mon { |
529 | my ($noderef, $port) = split /#/, shift, 2; |
658 | my ($nodeid, $port) = split /#/, shift, 2; |
530 | |
659 | |
531 | my $node = $NODE{$noderef} || add_node $noderef; |
660 | my $node = $NODE{$nodeid} || add_node $nodeid; |
532 | |
661 | |
533 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
662 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
534 | |
663 | |
535 | unless (ref $cb) { |
664 | unless (ref $cb) { |
536 | if (@_) { |
665 | if (@_) { |
… | |
… | |
545 | } |
674 | } |
546 | |
675 | |
547 | $node->monitor ($port, $cb); |
676 | $node->monitor ($port, $cb); |
548 | |
677 | |
549 | defined wantarray |
678 | defined wantarray |
550 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
679 | and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) }) |
551 | } |
680 | } |
552 | |
681 | |
553 | =item $guard = mon_guard $port, $ref, $ref... |
682 | =item $guard = mon_guard $port, $ref, $ref... |
554 | |
683 | |
555 | Monitors the given C<$port> and keeps the passed references. When the port |
684 | Monitors the given C<$port> and keeps the passed references. When the port |
… | |
… | |
578 | |
707 | |
579 | =item kil $port[, @reason] |
708 | =item kil $port[, @reason] |
580 | |
709 | |
581 | Kill the specified port with the given C<@reason>. |
710 | Kill the specified port with the given C<@reason>. |
582 | |
711 | |
583 | If no C<@reason> is specified, then the port is killed "normally" (ports |
712 | If no C<@reason> is specified, then the port is killed "normally" - |
584 | monitoring other ports will not necessarily die because a port dies |
713 | monitor callback will be invoked, but the kil will not cause linked ports |
585 | "normally"). |
714 | (C<mon $mport, $lport> form) to get killed. |
586 | |
715 | |
587 | Otherwise, linked ports get killed with the same reason (second form of |
716 | If a C<@reason> is specified, then linked ports (C<mon $mport, $lport> |
588 | C<mon>, see above). |
717 | form) get killed with the same reason. |
589 | |
718 | |
590 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
719 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
591 | will be reported as reason C<< die => $@ >>. |
720 | will be reported as reason C<< die => $@ >>. |
592 | |
721 | |
593 | Transport/communication errors are reported as C<< transport_error => |
722 | Transport/communication errors are reported as C<< transport_error => |
… | |
… | |
612 | the package, then the package above the package and so on (e.g. |
741 | the package, then the package above the package and so on (e.g. |
613 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
742 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
614 | exists or it runs out of package names. |
743 | exists or it runs out of package names. |
615 | |
744 | |
616 | The init function is then called with the newly-created port as context |
745 | The init function is then called with the newly-created port as context |
617 | object (C<$SELF>) and the C<@initdata> values as arguments. |
746 | object (C<$SELF>) and the C<@initdata> values as arguments. It I<must> |
|
|
747 | call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise |
|
|
748 | the port might not get created. |
618 | |
749 | |
619 | A common idiom is to pass a local port, immediately monitor the spawned |
750 | 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 |
751 | 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 |
752 | local port. This two-way monitoring ensures that both ports get cleaned up |
622 | when there is a problem. |
753 | when there is a problem. |
623 | |
754 | |
|
|
755 | C<spawn> guarantees that the C<$initfunc> has no visible effects on the |
|
|
756 | caller before C<spawn> returns (by delaying invocation when spawn is |
|
|
757 | called for the local node). |
|
|
758 | |
624 | Example: spawn a chat server port on C<$othernode>. |
759 | Example: spawn a chat server port on C<$othernode>. |
625 | |
760 | |
626 | # this node, executed from within a port context: |
761 | # this node, executed from within a port context: |
627 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
762 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
628 | mon $server; |
763 | mon $server; |
… | |
… | |
642 | |
777 | |
643 | sub _spawn { |
778 | sub _spawn { |
644 | my $port = shift; |
779 | my $port = shift; |
645 | my $init = shift; |
780 | my $init = shift; |
646 | |
781 | |
|
|
782 | # rcv will create the actual port |
647 | local $SELF = "$NODE#$port"; |
783 | local $SELF = "$NODE#$port"; |
648 | eval { |
784 | eval { |
649 | &{ load_func $init } |
785 | &{ load_func $init } |
650 | }; |
786 | }; |
651 | _self_die if $@; |
787 | _self_die if $@; |
652 | } |
788 | } |
653 | |
789 | |
654 | sub spawn(@) { |
790 | sub spawn(@) { |
655 | my ($noderef, undef) = split /#/, shift, 2; |
791 | my ($nodeid, undef) = split /#/, shift, 2; |
656 | |
792 | |
657 | my $id = "$RUNIQ." . $ID++; |
793 | my $id = $RUNIQ . ++$ID; |
658 | |
794 | |
659 | $_[0] =~ /::/ |
795 | $_[0] =~ /::/ |
660 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
796 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
661 | |
797 | |
662 | snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_; |
798 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
663 | |
799 | |
664 | "$noderef#$id" |
800 | "$nodeid#$id" |
665 | } |
801 | } |
|
|
802 | |
666 | |
803 | |
667 | =item after $timeout, @msg |
804 | =item after $timeout, @msg |
668 | |
805 | |
669 | =item after $timeout, $callback |
806 | =item after $timeout, $callback |
670 | |
807 | |
… | |
… | |
686 | ? $action[0]() |
823 | ? $action[0]() |
687 | : snd @action; |
824 | : snd @action; |
688 | }; |
825 | }; |
689 | } |
826 | } |
690 | |
827 | |
|
|
828 | =item cal $port, @msg, $callback[, $timeout] |
|
|
829 | |
|
|
830 | A simple form of RPC - sends a message to the given C<$port> with the |
|
|
831 | given contents (C<@msg>), but adds a reply port to the message. |
|
|
832 | |
|
|
833 | The reply port is created temporarily just for the purpose of receiving |
|
|
834 | the reply, and will be C<kil>ed when no longer needed. |
|
|
835 | |
|
|
836 | A reply message sent to the port is passed to the C<$callback> as-is. |
|
|
837 | |
|
|
838 | If an optional time-out (in seconds) is given and it is not C<undef>, |
|
|
839 | then the callback will be called without any arguments after the time-out |
|
|
840 | elapsed and the port is C<kil>ed. |
|
|
841 | |
|
|
842 | If no time-out is given (or it is C<undef>), then the local port will |
|
|
843 | monitor the remote port instead, so it eventually gets cleaned-up. |
|
|
844 | |
|
|
845 | Currently this function returns the temporary port, but this "feature" |
|
|
846 | might go in future versions unless you can make a convincing case that |
|
|
847 | this is indeed useful for something. |
|
|
848 | |
|
|
849 | =cut |
|
|
850 | |
|
|
851 | sub cal(@) { |
|
|
852 | my $timeout = ref $_[-1] ? undef : pop; |
|
|
853 | my $cb = pop; |
|
|
854 | |
|
|
855 | my $port = port { |
|
|
856 | undef $timeout; |
|
|
857 | kil $SELF; |
|
|
858 | &$cb; |
|
|
859 | }; |
|
|
860 | |
|
|
861 | if (defined $timeout) { |
|
|
862 | $timeout = AE::timer $timeout, 0, sub { |
|
|
863 | undef $timeout; |
|
|
864 | kil $port; |
|
|
865 | $cb->(); |
|
|
866 | }; |
|
|
867 | } else { |
|
|
868 | mon $_[0], sub { |
|
|
869 | kil $port; |
|
|
870 | $cb->(); |
|
|
871 | }; |
|
|
872 | } |
|
|
873 | |
|
|
874 | push @_, $port; |
|
|
875 | &snd; |
|
|
876 | |
|
|
877 | $port |
|
|
878 | } |
|
|
879 | |
|
|
880 | =back |
|
|
881 | |
|
|
882 | =head1 DISTRIBUTED DATABASE |
|
|
883 | |
|
|
884 | AnyEvent::MP comes with a simple distributed database. The database will |
|
|
885 | be mirrored asynchronously at all global nodes. Other nodes bind to one of |
|
|
886 | the global nodes for their needs. |
|
|
887 | |
|
|
888 | The database consists of a two-level hash - a hash contains a hash which |
|
|
889 | contains values. |
|
|
890 | |
|
|
891 | The top level hash key is called "family", and the second-level hash key |
|
|
892 | is simply called "key". |
|
|
893 | |
|
|
894 | The family must be alphanumeric, i.e. start with a letter and consist |
|
|
895 | of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>, |
|
|
896 | pretty much like Perl module names. |
|
|
897 | |
|
|
898 | As the family namespace is global, it is recommended to prefix family names |
|
|
899 | with the name of the application or module using it. |
|
|
900 | |
|
|
901 | The keys must be strings, with no other limitations. |
|
|
902 | |
|
|
903 | The values should preferably be strings, but other perl scalars should |
|
|
904 | work as well (such as undef, arrays and hashes). |
|
|
905 | |
|
|
906 | Every database entry is owned by one node - adding the same family/key |
|
|
907 | combination on multiple nodes will not cause discomfort for AnyEvent::MP, |
|
|
908 | but the result might be nondeterministic, i.e. the key might have |
|
|
909 | different values on different nodes. |
|
|
910 | |
|
|
911 | =item db_set $family => $key => $value |
|
|
912 | |
|
|
913 | Sets (or replaces) a key to the database. |
|
|
914 | |
|
|
915 | =item db_del $family => $key |
|
|
916 | |
|
|
917 | Deletes a key from the database. |
|
|
918 | |
|
|
919 | =item $guard = db_reg $family => $key [=> $value] |
|
|
920 | |
|
|
921 | Sets the key on the database and returns a guard. When the guard is |
|
|
922 | destroyed, the key is deleted from the database. If C<$value> is missing, |
|
|
923 | then C<undef> is used. |
|
|
924 | |
|
|
925 | =cut |
|
|
926 | |
691 | =back |
927 | =back |
692 | |
928 | |
693 | =head1 AnyEvent::MP vs. Distributed Erlang |
929 | =head1 AnyEvent::MP vs. Distributed Erlang |
694 | |
930 | |
695 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
931 | 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 |
932 | == 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 |
933 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
698 | sample: |
934 | sample: |
699 | |
935 | |
700 | http://www.Erlang.se/doc/programming_rules.shtml |
936 | http://www.erlang.se/doc/programming_rules.shtml |
701 | http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
937 | 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 |
938 | 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 |
939 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
704 | |
940 | |
705 | Despite the similarities, there are also some important differences: |
941 | Despite the similarities, there are also some important differences: |
706 | |
942 | |
707 | =over 4 |
943 | =over 4 |
708 | |
944 | |
709 | =item * Node IDs are arbitrary strings in AEMP. |
945 | =item * Node IDs are arbitrary strings in AEMP. |
710 | |
946 | |
711 | Erlang relies on special naming and DNS to work everywhere in the same |
947 | 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 |
948 | 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. |
949 | configuration or DNS), and possibly the addresses of some seed nodes, but |
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950 | will otherwise discover other nodes (and their IDs) itself. |
714 | |
951 | |
715 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
952 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
716 | uses "local ports are like remote ports". |
953 | uses "local ports are like remote ports". |
717 | |
954 | |
718 | The failure modes for local ports are quite different (runtime errors |
955 | The failure modes for local ports are quite different (runtime errors |
… | |
… | |
727 | ports being the special case/exception, where transport errors cannot |
964 | ports being the special case/exception, where transport errors cannot |
728 | occur. |
965 | occur. |
729 | |
966 | |
730 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
967 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
731 | |
968 | |
732 | Erlang uses processes that selectively receive messages, and therefore |
969 | Erlang uses processes that selectively receive messages out of order, and |
733 | needs a queue. AEMP is event based, queuing messages would serve no |
970 | therefore needs a queue. AEMP is event based, queuing messages would serve |
734 | useful purpose. For the same reason the pattern-matching abilities of |
971 | 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 |
972 | of AnyEvent::MP are more limited, as there is little need to be able to |
736 | filter messages without dequeing them. |
973 | filter messages without dequeuing them. |
737 | |
974 | |
738 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
975 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
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|
976 | being event-based, while Erlang is process-based. |
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|
977 | |
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|
978 | You cna have a look at L<Coro::MP> for a more Erlang-like process model on |
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|
979 | top of AEMP and Coro threads. |
739 | |
980 | |
740 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
981 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
741 | |
982 | |
742 | Sending messages in Erlang is synchronous and blocks the process (and |
983 | Sending messages in Erlang is synchronous and blocks the process until |
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|
984 | 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, |
985 | need a queue that can overflow). AEMP sends return immediately, connection |
744 | connection establishment is handled in the background. |
986 | establishment is handled in the background. |
745 | |
987 | |
746 | =item * Erlang suffers from silent message loss, AEMP does not. |
988 | =item * Erlang suffers from silent message loss, AEMP does not. |
747 | |
989 | |
748 | Erlang makes few guarantees on messages delivery - messages can get lost |
990 | 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, |
991 | 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). |
992 | b, and c, and the other side only receives messages a and c). |
751 | |
993 | |
752 | AEMP guarantees correct ordering, and the guarantee that after one message |
994 | 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 |
995 | 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 |
996 | same port are lost as well, until monitoring raises an error, so there are |
755 | sequence. |
997 | no silent "holes" in the message sequence. |
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998 | |
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999 | If you want your software to be very reliable, you have to cope with |
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1000 | corrupted and even out-of-order messages in both Erlang and AEMP. AEMP |
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1001 | simply tries to work better in common error cases, such as when a network |
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1002 | link goes down. |
756 | |
1003 | |
757 | =item * Erlang can send messages to the wrong port, AEMP does not. |
1004 | =item * Erlang can send messages to the wrong port, AEMP does not. |
758 | |
1005 | |
759 | In Erlang it is quite likely that a node that restarts reuses a process ID |
1006 | 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 |
1007 | process ID known to other nodes for a completely different process, |
761 | destined for that process to end up in an unrelated process. |
1008 | causing messages destined for that process to end up in an unrelated |
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|
1009 | process. |
762 | |
1010 | |
763 | AEMP never reuses port IDs, so old messages or old port IDs floating |
1011 | 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. |
1012 | around in the network will not be sent to an unrelated port. |
765 | |
1013 | |
766 | =item * Erlang uses unprotected connections, AEMP uses secure |
1014 | =item * Erlang uses unprotected connections, AEMP uses secure |
767 | authentication and can use TLS. |
1015 | authentication and can use TLS. |
768 | |
1016 | |
… | |
… | |
771 | |
1019 | |
772 | =item * The AEMP protocol is optimised for both text-based and binary |
1020 | =item * The AEMP protocol is optimised for both text-based and binary |
773 | communications. |
1021 | communications. |
774 | |
1022 | |
775 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
1023 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
776 | language independent text-only protocols (good for debugging) and binary, |
1024 | language independent text-only protocols (good for debugging), and binary, |
777 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
1025 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
778 | used, the protocol is actually completely text-based. |
1026 | used, the protocol is actually completely text-based. |
779 | |
1027 | |
780 | It has also been carefully designed to be implementable in other languages |
1028 | 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 |
1029 | with a minimum of work while gracefully degrading functionality to make the |
782 | protocol simple. |
1030 | protocol simple. |
783 | |
1031 | |
784 | =item * AEMP has more flexible monitoring options than Erlang. |
1032 | =item * AEMP has more flexible monitoring options than Erlang. |
785 | |
1033 | |
786 | In Erlang, you can chose to receive I<all> exit signals as messages |
1034 | 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 |
1035 | 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 |
1036 | difficult to implement. |
789 | Erlang, as one can choose between automatic kill, exit message or callback |
1037 | |
790 | on a per-process basis. |
1038 | Monitoring in AEMP is more flexible than in Erlang, as one can choose |
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|
1039 | between automatic kill, exit message or callback on a per-port basis. |
791 | |
1040 | |
792 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
1041 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
793 | |
1042 | |
794 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
1043 | 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). |
1044 | same way as linking is (except linking is unreliable in Erlang). |
… | |
… | |
817 | overhead, as well as having to keep a proxy object everywhere. |
1066 | overhead, as well as having to keep a proxy object everywhere. |
818 | |
1067 | |
819 | Strings can easily be printed, easily serialised etc. and need no special |
1068 | Strings can easily be printed, easily serialised etc. and need no special |
820 | procedures to be "valid". |
1069 | procedures to be "valid". |
821 | |
1070 | |
822 | And as a result, a miniport consists of a single closure stored in a |
1071 | And as a result, a port with just a default receiver consists of a single |
823 | global hash - it can't become much cheaper. |
1072 | code reference stored in a global hash - it can't become much cheaper. |
824 | |
1073 | |
825 | =item Why favour JSON, why not a real serialising format such as Storable? |
1074 | =item Why favour JSON, why not a real serialising format such as Storable? |
826 | |
1075 | |
827 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
1076 | 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 |
1077 | format, but currently there is no way to make a node use Storable by |
… | |
… | |
844 | |
1093 | |
845 | L<AnyEvent::MP::Intro> - a gentle introduction. |
1094 | L<AnyEvent::MP::Intro> - a gentle introduction. |
846 | |
1095 | |
847 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
1096 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
848 | |
1097 | |
849 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
1098 | L<AnyEvent::MP::Global> - network maintenance and port groups, to find |
850 | your applications. |
1099 | your applications. |
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1100 | |
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1101 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
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1102 | |
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1103 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
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1104 | all nodes. |
851 | |
1105 | |
852 | L<AnyEvent>. |
1106 | L<AnyEvent>. |
853 | |
1107 | |
854 | =head1 AUTHOR |
1108 | =head1 AUTHOR |
855 | |
1109 | |