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 | |
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12 | $SELF # receiving/own port id in rcv callbacks |
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13 | |
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14 | # initialise the node so it can send/receive messages |
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15 | configure; |
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16 | |
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17 | # ports are message destinations |
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18 | |
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19 | # sending messages |
13 | snd $port, type => data...; |
20 | snd $port, type => data...; |
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21 | snd $port, @msg; |
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22 | snd @msg_with_first_element_being_a_port; |
14 | |
23 | |
15 | $SELF # receiving/own port id in rcv callbacks |
24 | # creating/using ports, the simple way |
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25 | my $simple_port = port { my @msg = @_ }; |
16 | |
26 | |
17 | rcv $port, smartmatch => $cb->($port, @msg); |
27 | # creating/using ports, tagged message matching |
18 | |
28 | my $port = port; |
19 | # examples: |
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20 | rcv $port2, ping => sub { snd $_[0], "pong"; 0 }; |
29 | rcv $port, ping => sub { snd $_[0], "pong" }; |
21 | rcv $port1, pong => sub { warn "pong received\n" }; |
30 | rcv $port, pong => sub { warn "pong received\n" }; |
22 | snd $port2, ping => $port1; |
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23 | |
31 | |
24 | # more, smarter, matches (_any_ is exported by this module) |
32 | # create a port on another node |
25 | rcv $port, [child_died => $pid] => sub { ... |
33 | my $port = spawn $node, $initfunc, @initdata; |
26 | rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3 |
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 | |
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39 | # monitoring |
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40 | mon $localport, $cb->(@msg) # callback is invoked on death |
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41 | mon $localport, $otherport # kill otherport on abnormal death |
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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 | }; |
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51 | |
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52 | =head1 CURRENT STATUS |
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53 | |
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54 | bin/aemp - stable. |
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55 | AnyEvent::MP - stable API, should work. |
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56 | AnyEvent::MP::Intro - explains most concepts. |
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57 | AnyEvent::MP::Kernel - mostly stable API. |
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58 | AnyEvent::MP::Global - stable API. |
27 | |
59 | |
28 | =head1 DESCRIPTION |
60 | =head1 DESCRIPTION |
29 | |
61 | |
30 | This module (-family) implements a simple message passing framework. |
62 | This module (-family) implements a simple message passing framework. |
31 | |
63 | |
32 | Despite its simplicity, you can securely message other processes running |
64 | Despite its simplicity, you can securely message other processes running |
33 | on the same or other hosts. |
65 | on the same or other hosts, and you can supervise entities remotely. |
34 | |
66 | |
35 | 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> |
36 | manual page. |
68 | manual page and the examples under F<eg/>. |
37 | |
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38 | At the moment, this module family is severly broken and underdocumented, |
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39 | so do not use. This was uploaded mainly to reserve the CPAN namespace - |
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40 | stay tuned! The basic API should be finished, however. |
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41 | |
69 | |
42 | =head1 CONCEPTS |
70 | =head1 CONCEPTS |
43 | |
71 | |
44 | =over 4 |
72 | =over 4 |
45 | |
73 | |
46 | =item port |
74 | =item port |
47 | |
75 | |
48 | A port is something you can send messages to with the C<snd> function, and |
76 | Not to be confused with a TCP port, a "port" is something you can send |
49 | you can register C<rcv> handlers with. All C<rcv> handlers will receive |
77 | messages to (with the C<snd> function). |
50 | messages they match, messages will not be queued. |
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51 | |
78 | |
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79 | Ports allow you to register C<rcv> handlers that can match all or just |
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80 | some messages. Messages send to ports will not be queued, regardless of |
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81 | anything was listening for them or not. |
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82 | |
52 | =item port id - C<noderef#portname> |
83 | =item port ID - C<nodeid#portname> |
53 | |
84 | |
54 | A port id is always the noderef, a hash-mark (C<#>) as separator, followed |
85 | A port ID is the concatenation of a node ID, a hash-mark (C<#>) as |
55 | by a port name (a printable string of unspecified format). |
86 | separator, and a port name (a printable string of unspecified format). |
56 | |
87 | |
57 | =item node |
88 | =item node |
58 | |
89 | |
59 | A node is a single process containing at least one port - the node |
90 | A node is a single process containing at least one port - the node port, |
60 | port. You can send messages to node ports to let them create new ports, |
91 | which enables nodes to manage each other remotely, and to create new |
61 | among other things. |
92 | ports. |
62 | |
93 | |
63 | Initially, nodes are either private (single-process only) or hidden |
94 | Nodes are either public (have one or more listening ports) or private |
64 | (connected to a master node only). Only when they epxlicitly "become |
95 | (no listening ports). Private nodes cannot talk to other private nodes |
65 | public" can you send them messages from unrelated other nodes. |
96 | currently. |
66 | |
97 | |
67 | =item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> |
98 | =item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*> |
68 | |
99 | |
69 | A noderef is a string that either uniquely identifies a given node (for |
100 | A node ID is a string that uniquely identifies the node within a |
70 | private and hidden nodes), or contains a recipe on how to reach a given |
101 | network. Depending on the configuration used, node IDs can look like a |
71 | node (for public nodes). |
102 | hostname, a hostname and a port, or a random string. AnyEvent::MP itself |
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103 | doesn't interpret node IDs in any way. |
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104 | |
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105 | =item binds - C<ip:port> |
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106 | |
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107 | Nodes can only talk to each other by creating some kind of connection to |
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108 | each other. To do this, nodes should listen on one or more local transport |
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109 | endpoints - binds. Currently, only standard C<ip:port> specifications can |
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110 | be used, which specify TCP ports to listen on. |
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111 | |
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112 | =item seed nodes |
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113 | |
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114 | When a node starts, it knows nothing about the network. To teach the node |
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115 | about the network it first has to contact some other node within the |
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116 | network. This node is called a seed. |
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117 | |
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118 | Apart from the fact that other nodes know them as seed nodes and they have |
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119 | to have fixed listening addresses, seed nodes are perfectly normal nodes - |
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120 | any node can function as a seed node for others. |
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121 | |
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122 | In addition to discovering the network, seed nodes are also used to |
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123 | maintain the network and to connect nodes that otherwise would have |
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124 | trouble connecting. They form the backbone of an AnyEvent::MP network. |
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125 | |
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126 | Seed nodes are expected to be long-running, and at least one seed node |
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127 | should always be available. They should also be relatively responsive - a |
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128 | seed node that blocks for long periods will slow down everybody else. |
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129 | |
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130 | =item seeds - C<host:port> |
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131 | |
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132 | Seeds are transport endpoint(s) (usually a hostname/IP address and a |
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133 | TCP port) of nodes that should be used as seed nodes. |
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134 | |
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135 | The nodes listening on those endpoints are expected to be long-running, |
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136 | and at least one of those should always be available. When nodes run out |
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137 | of connections (e.g. due to a network error), they try to re-establish |
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138 | connections to some seednodes again to join the network. |
72 | |
139 | |
73 | =back |
140 | =back |
74 | |
141 | |
75 | =head1 VARIABLES/FUNCTIONS |
142 | =head1 VARIABLES/FUNCTIONS |
76 | |
143 | |
… | |
… | |
78 | |
145 | |
79 | =cut |
146 | =cut |
80 | |
147 | |
81 | package AnyEvent::MP; |
148 | package AnyEvent::MP; |
82 | |
149 | |
83 | use AnyEvent::MP::Base; |
150 | use AnyEvent::MP::Kernel; |
84 | |
151 | |
85 | use common::sense; |
152 | use common::sense; |
86 | |
153 | |
87 | use Carp (); |
154 | use Carp (); |
88 | |
155 | |
89 | use AE (); |
156 | use AE (); |
90 | |
157 | |
91 | use base "Exporter"; |
158 | use base "Exporter"; |
92 | |
159 | |
93 | our $VERSION = '0.02'; |
160 | our $VERSION = 1.29; |
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161 | |
94 | our @EXPORT = qw( |
162 | our @EXPORT = qw( |
95 | NODE $NODE *SELF node_of _any_ |
163 | NODE $NODE *SELF node_of after |
96 | become_slave become_public |
164 | configure |
97 | snd rcv mon kil reg psub |
165 | snd rcv mon mon_guard kil psub peval spawn cal |
98 | port |
166 | port |
99 | ); |
167 | ); |
100 | |
168 | |
101 | our $SELF; |
169 | our $SELF; |
102 | |
170 | |
… | |
… | |
106 | kil $SELF, die => $msg; |
174 | kil $SELF, die => $msg; |
107 | } |
175 | } |
108 | |
176 | |
109 | =item $thisnode = NODE / $NODE |
177 | =item $thisnode = NODE / $NODE |
110 | |
178 | |
111 | The C<NODE> function returns, and the C<$NODE> variable contains |
179 | The C<NODE> function returns, and the C<$NODE> variable contains, the node |
112 | the noderef of the local node. The value is initialised by a call |
180 | ID of the node running in the current process. This value is initialised by |
113 | to C<become_public> or C<become_slave>, after which all local port |
181 | a call to C<configure>. |
114 | identifiers become invalid. |
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115 | |
182 | |
116 | =item $noderef = node_of $portid |
183 | =item $nodeid = node_of $port |
117 | |
184 | |
118 | Extracts and returns the noderef from a portid or a noderef. |
185 | Extracts and returns the node ID from a port ID or a node ID. |
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186 | |
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187 | =item configure $profile, key => value... |
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188 | |
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189 | =item configure key => value... |
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190 | |
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191 | Before a node can talk to other nodes on the network (i.e. enter |
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192 | "distributed mode") it has to configure itself - the minimum a node needs |
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193 | to know is its own name, and optionally it should know the addresses of |
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194 | some other nodes in the network to discover other nodes. |
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195 | |
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196 | The key/value pairs are basically the same ones as documented for the |
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197 | F<aemp> command line utility (sans the set/del prefix). |
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198 | |
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199 | This function configures a node - it must be called exactly once (or |
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200 | never) before calling other AnyEvent::MP functions. |
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201 | |
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202 | =over 4 |
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203 | |
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204 | =item step 1, gathering configuration from profiles |
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205 | |
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206 | The function first looks up a profile in the aemp configuration (see the |
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207 | L<aemp> commandline utility). The profile name can be specified via the |
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208 | named C<profile> parameter or can simply be the first parameter). If it is |
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209 | missing, then the nodename (F<uname -n>) will be used as profile name. |
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210 | |
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211 | The profile data is then gathered as follows: |
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212 | |
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213 | First, all remaining key => value pairs (all of which are conveniently |
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214 | undocumented at the moment) will be interpreted as configuration |
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215 | data. Then they will be overwritten by any values specified in the global |
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216 | default configuration (see the F<aemp> utility), then the chain of |
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217 | profiles chosen by the profile name (and any C<parent> attributes). |
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218 | |
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219 | That means that the values specified in the profile have highest priority |
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220 | and the values specified directly via C<configure> have lowest priority, |
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221 | and can only be used to specify defaults. |
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222 | |
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223 | If the profile specifies a node ID, then this will become the node ID of |
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224 | this process. If not, then the profile name will be used as node ID. The |
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225 | special node ID of C<anon/> will be replaced by a random node ID. |
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226 | |
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227 | =item step 2, bind listener sockets |
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228 | |
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229 | The next step is to look up the binds in the profile, followed by binding |
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230 | aemp protocol listeners on all binds specified (it is possible and valid |
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231 | to have no binds, meaning that the node cannot be contacted form the |
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232 | outside. This means the node cannot talk to other nodes that also have no |
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233 | binds, but it can still talk to all "normal" nodes). |
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234 | |
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235 | If the profile does not specify a binds list, then a default of C<*> is |
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236 | used, meaning the node will bind on a dynamically-assigned port on every |
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237 | local IP address it finds. |
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238 | |
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239 | =item step 3, connect to seed nodes |
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240 | |
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241 | As the last step, the seeds list from the profile is passed to the |
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242 | L<AnyEvent::MP::Global> module, which will then use it to keep |
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243 | connectivity with at least one node at any point in time. |
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244 | |
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245 | =back |
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246 | |
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247 | Example: become a distributed node using the local node name as profile. |
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248 | This should be the most common form of invocation for "daemon"-type nodes. |
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249 | |
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250 | configure |
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251 | |
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252 | Example: become an anonymous node. This form is often used for commandline |
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253 | clients. |
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254 | |
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255 | configure nodeid => "anon/"; |
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256 | |
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257 | Example: configure a node using a profile called seed, which si suitable |
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258 | for a seed node as it binds on all local addresses on a fixed port (4040, |
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259 | customary for aemp). |
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260 | |
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261 | # use the aemp commandline utility |
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262 | # aemp profile seed nodeid anon/ binds '*:4040' |
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263 | |
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264 | # then use it |
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265 | configure profile => "seed"; |
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266 | |
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267 | # or simply use aemp from the shell again: |
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268 | # aemp run profile seed |
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269 | |
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270 | # or provide a nicer-to-remember nodeid |
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271 | # aemp run profile seed nodeid "$(hostname)" |
119 | |
272 | |
120 | =item $SELF |
273 | =item $SELF |
121 | |
274 | |
122 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
275 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
123 | blocks. |
276 | blocks. |
124 | |
277 | |
125 | =item SELF, %SELF, @SELF... |
278 | =item *SELF, SELF, %SELF, @SELF... |
126 | |
279 | |
127 | Due to some quirks in how perl exports variables, it is impossible to |
280 | Due to some quirks in how perl exports variables, it is impossible to |
128 | just export C<$SELF>, all the symbols called C<SELF> are exported by this |
281 | just export C<$SELF>, all the symbols named C<SELF> are exported by this |
129 | module, but only C<$SELF> is currently used. |
282 | module, but only C<$SELF> is currently used. |
130 | |
283 | |
131 | =item snd $portid, type => @data |
284 | =item snd $port, type => @data |
132 | |
285 | |
133 | =item snd $portid, @msg |
286 | =item snd $port, @msg |
134 | |
287 | |
135 | Send the given message to the given port ID, which can identify either |
288 | Send the given message to the given port, which can identify either a |
136 | a local or a remote port, and can be either a string or soemthignt hat |
289 | local or a remote port, and must be a port ID. |
137 | stringifies a sa port ID (such as a port object :). |
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138 | |
290 | |
139 | While the message can be about anything, it is highly recommended to use a |
291 | While the message can be almost anything, it is highly recommended to |
140 | string as first element (a portid, or some word that indicates a request |
292 | use a string as first element (a port ID, or some word that indicates a |
141 | type etc.). |
293 | request type etc.) and to consist if only simple perl values (scalars, |
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294 | arrays, hashes) - if you think you need to pass an object, think again. |
142 | |
295 | |
143 | The message data effectively becomes read-only after a call to this |
296 | The message data logically becomes read-only after a call to this |
144 | function: modifying any argument is not allowed and can cause many |
297 | function: modifying any argument (or values referenced by them) is |
145 | problems. |
298 | forbidden, as there can be considerable time between the call to C<snd> |
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299 | and the time the message is actually being serialised - in fact, it might |
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300 | never be copied as within the same process it is simply handed to the |
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301 | receiving port. |
146 | |
302 | |
147 | The type of data you can transfer depends on the transport protocol: when |
303 | The type of data you can transfer depends on the transport protocol: when |
148 | JSON is used, then only strings, numbers and arrays and hashes consisting |
304 | JSON is used, then only strings, numbers and arrays and hashes consisting |
149 | of those are allowed (no objects). When Storable is used, then anything |
305 | of those are allowed (no objects). When Storable is used, then anything |
150 | that Storable can serialise and deserialise is allowed, and for the local |
306 | that Storable can serialise and deserialise is allowed, and for the local |
151 | node, anything can be passed. |
307 | node, anything can be passed. Best rely only on the common denominator of |
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308 | these. |
152 | |
309 | |
153 | =item kil $portid[, @reason] |
310 | =item $local_port = port |
154 | |
311 | |
155 | Kill the specified port with the given C<@reason>. |
312 | Create a new local port object and returns its port ID. Initially it has |
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313 | no callbacks set and will throw an error when it receives messages. |
156 | |
314 | |
157 | If no C<@reason> is specified, then the port is killed "normally" (linked |
315 | =item $local_port = port { my @msg = @_ } |
158 | ports will not be kileld, or even notified). |
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159 | |
316 | |
160 | Otherwise, linked ports get killed with the same reason (second form of |
317 | Creates a new local port, and returns its ID. Semantically the same as |
161 | C<mon>, see below). |
318 | creating a port and calling C<rcv $port, $callback> on it. |
162 | |
319 | |
163 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
320 | The block will be called for every message received on the port, with the |
164 | will be reported as reason C<< die => $@ >>. |
321 | global variable C<$SELF> set to the port ID. Runtime errors will cause the |
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322 | port to be C<kil>ed. The message will be passed as-is, no extra argument |
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323 | (i.e. no port ID) will be passed to the callback. |
165 | |
324 | |
166 | Transport/communication errors are reported as C<< transport_error => |
325 | If you want to stop/destroy the port, simply C<kil> it: |
167 | $message >>. |
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168 | |
326 | |
169 | =item $guard = mon $portid, $cb->(@reason) |
327 | my $port = port { |
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328 | my @msg = @_; |
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329 | ... |
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330 | kil $SELF; |
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331 | }; |
170 | |
332 | |
171 | =item $guard = mon $portid, $otherport |
333 | =cut |
172 | |
334 | |
173 | =item $guard = mon $portid, $otherport, @msg |
335 | sub rcv($@); |
174 | |
336 | |
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337 | sub _kilme { |
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338 | die "received message on port without callback"; |
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339 | } |
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340 | |
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341 | sub port(;&) { |
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342 | my $id = "$UNIQ." . $ID++; |
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343 | my $port = "$NODE#$id"; |
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344 | |
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345 | rcv $port, shift || \&_kilme; |
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346 | |
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347 | $port |
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348 | } |
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349 | |
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350 | =item rcv $local_port, $callback->(@msg) |
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351 | |
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352 | Replaces the default callback on the specified port. There is no way to |
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353 | remove the default callback: use C<sub { }> to disable it, or better |
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354 | C<kil> the port when it is no longer needed. |
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355 | |
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356 | The global C<$SELF> (exported by this module) contains C<$port> while |
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357 | executing the callback. Runtime errors during callback execution will |
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358 | result in the port being C<kil>ed. |
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359 | |
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360 | The default callback received all messages not matched by a more specific |
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361 | C<tag> match. |
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362 | |
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363 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
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364 | |
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365 | Register (or replace) callbacks to be called on messages starting with the |
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366 | given tag on the given port (and return the port), or unregister it (when |
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367 | C<$callback> is C<$undef> or missing). There can only be one callback |
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368 | registered for each tag. |
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369 | |
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370 | The original message will be passed to the callback, after the first |
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371 | element (the tag) has been removed. The callback will use the same |
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372 | environment as the default callback (see above). |
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373 | |
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374 | Example: create a port and bind receivers on it in one go. |
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375 | |
|
|
376 | my $port = rcv port, |
|
|
377 | msg1 => sub { ... }, |
|
|
378 | msg2 => sub { ... }, |
|
|
379 | ; |
|
|
380 | |
|
|
381 | Example: create a port, bind receivers and send it in a message elsewhere |
|
|
382 | in one go: |
|
|
383 | |
|
|
384 | snd $otherport, reply => |
|
|
385 | rcv port, |
|
|
386 | msg1 => sub { ... }, |
|
|
387 | ... |
|
|
388 | ; |
|
|
389 | |
|
|
390 | Example: temporarily register a rcv callback for a tag matching some port |
|
|
391 | (e.g. for an rpc reply) and unregister it after a message was received. |
|
|
392 | |
|
|
393 | rcv $port, $otherport => sub { |
|
|
394 | my @reply = @_; |
|
|
395 | |
|
|
396 | rcv $SELF, $otherport; |
|
|
397 | }; |
|
|
398 | |
|
|
399 | =cut |
|
|
400 | |
|
|
401 | sub rcv($@) { |
|
|
402 | my $port = shift; |
|
|
403 | my ($nodeid, $portid) = split /#/, $port, 2; |
|
|
404 | |
|
|
405 | $NODE{$nodeid} == $NODE{""} |
|
|
406 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
|
|
407 | |
|
|
408 | while (@_) { |
|
|
409 | if (ref $_[0]) { |
|
|
410 | if (my $self = $PORT_DATA{$portid}) { |
|
|
411 | "AnyEvent::MP::Port" eq ref $self |
|
|
412 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
|
|
413 | |
|
|
414 | $self->[0] = shift; |
|
|
415 | } else { |
|
|
416 | my $cb = shift; |
|
|
417 | $PORT{$portid} = sub { |
|
|
418 | local $SELF = $port; |
|
|
419 | eval { &$cb }; _self_die if $@; |
|
|
420 | }; |
|
|
421 | } |
|
|
422 | } elsif (defined $_[0]) { |
|
|
423 | my $self = $PORT_DATA{$portid} ||= do { |
|
|
424 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
|
|
425 | |
|
|
426 | $PORT{$portid} = sub { |
|
|
427 | local $SELF = $port; |
|
|
428 | |
|
|
429 | if (my $cb = $self->[1]{$_[0]}) { |
|
|
430 | shift; |
|
|
431 | eval { &$cb }; _self_die if $@; |
|
|
432 | } else { |
|
|
433 | &{ $self->[0] }; |
|
|
434 | } |
|
|
435 | }; |
|
|
436 | |
|
|
437 | $self |
|
|
438 | }; |
|
|
439 | |
|
|
440 | "AnyEvent::MP::Port" eq ref $self |
|
|
441 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
|
|
442 | |
|
|
443 | my ($tag, $cb) = splice @_, 0, 2; |
|
|
444 | |
|
|
445 | if (defined $cb) { |
|
|
446 | $self->[1]{$tag} = $cb; |
|
|
447 | } else { |
|
|
448 | delete $self->[1]{$tag}; |
|
|
449 | } |
|
|
450 | } |
|
|
451 | } |
|
|
452 | |
|
|
453 | $port |
|
|
454 | } |
|
|
455 | |
|
|
456 | =item peval $port, $coderef[, @args] |
|
|
457 | |
|
|
458 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
|
|
459 | when the code throews an exception the C<$port> will be killed. |
|
|
460 | |
|
|
461 | Any remaining args will be passed to the callback. Any return values will |
|
|
462 | be returned to the caller. |
|
|
463 | |
|
|
464 | This is useful when you temporarily want to execute code in the context of |
|
|
465 | a port. |
|
|
466 | |
|
|
467 | Example: create a port and run some initialisation code in it's context. |
|
|
468 | |
|
|
469 | my $port = port { ... }; |
|
|
470 | |
|
|
471 | peval $port, sub { |
|
|
472 | init |
|
|
473 | or die "unable to init"; |
|
|
474 | }; |
|
|
475 | |
|
|
476 | =cut |
|
|
477 | |
|
|
478 | sub peval($$) { |
|
|
479 | local $SELF = shift; |
|
|
480 | my $cb = shift; |
|
|
481 | |
|
|
482 | if (wantarray) { |
|
|
483 | my @res = eval { &$cb }; |
|
|
484 | _self_die if $@; |
|
|
485 | @res |
|
|
486 | } else { |
|
|
487 | my $res = eval { &$cb }; |
|
|
488 | _self_die if $@; |
|
|
489 | $res |
|
|
490 | } |
|
|
491 | } |
|
|
492 | |
|
|
493 | =item $closure = psub { BLOCK } |
|
|
494 | |
|
|
495 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
|
|
496 | closure is executed, sets up the environment in the same way as in C<rcv> |
|
|
497 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
|
|
498 | |
|
|
499 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
|
|
500 | BLOCK }, @_ } >>. |
|
|
501 | |
|
|
502 | This is useful when you register callbacks from C<rcv> callbacks: |
|
|
503 | |
|
|
504 | rcv delayed_reply => sub { |
|
|
505 | my ($delay, @reply) = @_; |
|
|
506 | my $timer = AE::timer $delay, 0, psub { |
|
|
507 | snd @reply, $SELF; |
|
|
508 | }; |
|
|
509 | }; |
|
|
510 | |
|
|
511 | =cut |
|
|
512 | |
|
|
513 | sub psub(&) { |
|
|
514 | my $cb = shift; |
|
|
515 | |
|
|
516 | my $port = $SELF |
|
|
517 | or Carp::croak "psub can only be called from within rcv or psub callbacks, not"; |
|
|
518 | |
|
|
519 | sub { |
|
|
520 | local $SELF = $port; |
|
|
521 | |
|
|
522 | if (wantarray) { |
|
|
523 | my @res = eval { &$cb }; |
|
|
524 | _self_die if $@; |
|
|
525 | @res |
|
|
526 | } else { |
|
|
527 | my $res = eval { &$cb }; |
|
|
528 | _self_die if $@; |
|
|
529 | $res |
|
|
530 | } |
|
|
531 | } |
|
|
532 | } |
|
|
533 | |
|
|
534 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
|
|
535 | |
|
|
536 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
537 | |
|
|
538 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
539 | |
|
|
540 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
|
|
541 | |
175 | Monitor the given port and do something when the port is killed. |
542 | Monitor the given port and do something when the port is killed or |
|
|
543 | messages to it were lost, and optionally return a guard that can be used |
|
|
544 | to stop monitoring again. |
176 | |
545 | |
177 | In the first form, the callback is simply called with any number |
546 | In the first form (callback), the callback is simply called with any |
178 | of C<@reason> elements (no @reason means that the port was deleted |
547 | number of C<@reason> elements (no @reason means that the port was deleted |
179 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
548 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
180 | C<eval> if unsure. |
549 | C<eval> if unsure. |
181 | |
550 | |
182 | In the second form, the other port will be C<kil>'ed with C<@reason>, iff |
551 | In the second form (another port given), the other port (C<$rcvport>) |
183 | a @reason was specified, i.e. on "normal" kils nothing happens, while |
552 | will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on |
184 | under all other conditions, the other port is killed with the same reason. |
553 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
554 | port is killed with the same reason. |
185 | |
555 | |
|
|
556 | The third form (kill self) is the same as the second form, except that |
|
|
557 | C<$rvport> defaults to C<$SELF>. |
|
|
558 | |
186 | In the last form, a message of the form C<@msg, @reason> will be C<snd>. |
559 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
560 | C<snd>. |
|
|
561 | |
|
|
562 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
|
|
563 | alert was raised), they are removed and will not trigger again. |
|
|
564 | |
|
|
565 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
566 | a local port (or callback). The reason is that kill messages might get |
|
|
567 | lost, just like any other message. Another less obvious reason is that |
|
|
568 | even monitoring requests can get lost (for example, when the connection |
|
|
569 | to the other node goes down permanently). When monitoring a port locally |
|
|
570 | these problems do not exist. |
|
|
571 | |
|
|
572 | C<mon> effectively guarantees that, in the absence of hardware failures, |
|
|
573 | after starting the monitor, either all messages sent to the port will |
|
|
574 | arrive, or the monitoring action will be invoked after possible message |
|
|
575 | loss has been detected. No messages will be lost "in between" (after |
|
|
576 | the first lost message no further messages will be received by the |
|
|
577 | port). After the monitoring action was invoked, further messages might get |
|
|
578 | delivered again. |
|
|
579 | |
|
|
580 | Inter-host-connection timeouts and monitoring depend on the transport |
|
|
581 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
|
|
582 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
|
|
583 | non-idle connection, and usually around two hours for idle connections). |
|
|
584 | |
|
|
585 | This means that monitoring is good for program errors and cleaning up |
|
|
586 | stuff eventually, but they are no replacement for a timeout when you need |
|
|
587 | to ensure some maximum latency. |
187 | |
588 | |
188 | Example: call a given callback when C<$port> is killed. |
589 | Example: call a given callback when C<$port> is killed. |
189 | |
590 | |
190 | mon $port, sub { warn "port died because of <@_>\n" }; |
591 | mon $port, sub { warn "port died because of <@_>\n" }; |
191 | |
592 | |
192 | Example: kill ourselves when C<$port> is killed abnormally. |
593 | Example: kill ourselves when C<$port> is killed abnormally. |
193 | |
594 | |
194 | mon $port, $self; |
595 | mon $port; |
195 | |
596 | |
196 | Example: send us a restart message another C<$port> is killed. |
597 | Example: send us a restart message when another C<$port> is killed. |
197 | |
598 | |
198 | mon $port, $self => "restart"; |
599 | mon $port, $self => "restart"; |
199 | |
600 | |
200 | =cut |
601 | =cut |
201 | |
602 | |
202 | sub mon { |
603 | sub mon { |
203 | my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift); |
604 | my ($nodeid, $port) = split /#/, shift, 2; |
204 | |
605 | |
205 | my $node = $NODE{$noderef} || add_node $noderef; |
606 | my $node = $NODE{$nodeid} || add_node $nodeid; |
206 | |
607 | |
207 | #TODO: ports must not be references |
608 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
208 | if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) { |
609 | |
|
|
610 | unless (ref $cb) { |
209 | if (@_) { |
611 | if (@_) { |
210 | # send a kill info message |
612 | # send a kill info message |
211 | my (@msg) = ($cb, @_); |
613 | my (@msg) = ($cb, @_); |
212 | $cb = sub { snd @msg, @_ }; |
614 | $cb = sub { snd @msg, @_ }; |
213 | } else { |
615 | } else { |
… | |
… | |
218 | } |
620 | } |
219 | |
621 | |
220 | $node->monitor ($port, $cb); |
622 | $node->monitor ($port, $cb); |
221 | |
623 | |
222 | defined wantarray |
624 | defined wantarray |
223 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
625 | and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }) |
224 | } |
626 | } |
225 | |
627 | |
226 | =item $guard = mon_guard $port, $ref, $ref... |
628 | =item $guard = mon_guard $port, $ref, $ref... |
227 | |
629 | |
228 | Monitors the given C<$port> and keeps the passed references. When the port |
630 | Monitors the given C<$port> and keeps the passed references. When the port |
229 | is killed, the references will be freed. |
631 | is killed, the references will be freed. |
230 | |
632 | |
231 | Optionally returns a guard that will stop the monitoring. |
633 | Optionally returns a guard that will stop the monitoring. |
232 | |
634 | |
233 | This function is useful when you create e.g. timers or other watchers and |
635 | This function is useful when you create e.g. timers or other watchers and |
234 | want to free them when the port gets killed: |
636 | want to free them when the port gets killed (note the use of C<psub>): |
235 | |
637 | |
236 | $port->rcv (start => sub { |
638 | $port->rcv (start => sub { |
237 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { |
639 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub { |
238 | undef $timer if 0.9 < rand; |
640 | undef $timer if 0.9 < rand; |
239 | }); |
641 | }); |
240 | }); |
642 | }); |
241 | |
643 | |
242 | =cut |
644 | =cut |
243 | |
645 | |
244 | sub mon_guard { |
646 | sub mon_guard { |
245 | my ($port, @refs) = @_; |
647 | my ($port, @refs) = @_; |
246 | |
648 | |
|
|
649 | #TODO: mon-less form? |
|
|
650 | |
247 | mon $port, sub { 0 && @refs } |
651 | mon $port, sub { 0 && @refs } |
248 | } |
652 | } |
249 | |
653 | |
250 | =item lnk $port1, $port2 |
654 | =item kil $port[, @reason] |
251 | |
655 | |
252 | Link two ports. This is simply a shorthand for: |
656 | Kill the specified port with the given C<@reason>. |
253 | |
657 | |
254 | mon $port1, $port2; |
658 | If no C<@reason> is specified, then the port is killed "normally" - |
255 | mon $port2, $port1; |
659 | monitor callback will be invoked, but the kil will not cause linked ports |
|
|
660 | (C<mon $mport, $lport> form) to get killed. |
256 | |
661 | |
257 | It means that if either one is killed abnormally, the other one gets |
662 | If a C<@reason> is specified, then linked ports (C<mon $mport, $lport> |
258 | killed as well. |
663 | form) get killed with the same reason. |
259 | |
664 | |
260 | =item $local_port = port |
665 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
|
|
666 | will be reported as reason C<< die => $@ >>. |
261 | |
667 | |
262 | Create a new local port object that supports message matching. |
668 | Transport/communication errors are reported as C<< transport_error => |
|
|
669 | $message >>. |
263 | |
670 | |
264 | =item $portid = port { my @msg = @_; $finished } |
671 | =cut |
265 | |
672 | |
266 | Creates a "mini port", that is, a very lightweight port without any |
673 | =item $port = spawn $node, $initfunc[, @initdata] |
267 | pattern matching behind it, and returns its ID. |
|
|
268 | |
674 | |
269 | The block will be called for every message received on the port. When the |
675 | Creates a port on the node C<$node> (which can also be a port ID, in which |
270 | callback returns a true value its job is considered "done" and the port |
676 | case it's the node where that port resides). |
271 | will be destroyed. Otherwise it will stay alive. |
|
|
272 | |
677 | |
273 | The message will be passed as-is, no extra argument (i.e. no port id) will |
678 | The port ID of the newly created port is returned immediately, and it is |
274 | be passed to the callback. |
679 | possible to immediately start sending messages or to monitor the port. |
275 | |
680 | |
276 | If you need the local port id in the callback, this works nicely: |
681 | After the port has been created, the init function is called on the remote |
|
|
682 | node, in the same context as a C<rcv> callback. This function must be a |
|
|
683 | fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To |
|
|
684 | specify a function in the main program, use C<::name>. |
277 | |
685 | |
278 | my $port; $port = miniport { |
686 | If the function doesn't exist, then the node tries to C<require> |
279 | snd $otherport, reply => $port; |
687 | the package, then the package above the package and so on (e.g. |
|
|
688 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
|
|
689 | exists or it runs out of package names. |
|
|
690 | |
|
|
691 | The init function is then called with the newly-created port as context |
|
|
692 | object (C<$SELF>) and the C<@initdata> values as arguments. It I<must> |
|
|
693 | call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise |
|
|
694 | the port might not get created. |
|
|
695 | |
|
|
696 | A common idiom is to pass a local port, immediately monitor the spawned |
|
|
697 | port, and in the remote init function, immediately monitor the passed |
|
|
698 | local port. This two-way monitoring ensures that both ports get cleaned up |
|
|
699 | when there is a problem. |
|
|
700 | |
|
|
701 | C<spawn> guarantees that the C<$initfunc> has no visible effects on the |
|
|
702 | caller before C<spawn> returns (by delaying invocation when spawn is |
|
|
703 | called for the local node). |
|
|
704 | |
|
|
705 | Example: spawn a chat server port on C<$othernode>. |
|
|
706 | |
|
|
707 | # this node, executed from within a port context: |
|
|
708 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
|
|
709 | mon $server; |
|
|
710 | |
|
|
711 | # init function on C<$othernode> |
|
|
712 | sub connect { |
|
|
713 | my ($srcport) = @_; |
|
|
714 | |
|
|
715 | mon $srcport; |
|
|
716 | |
|
|
717 | rcv $SELF, sub { |
|
|
718 | ... |
|
|
719 | }; |
|
|
720 | } |
|
|
721 | |
|
|
722 | =cut |
|
|
723 | |
|
|
724 | sub _spawn { |
|
|
725 | my $port = shift; |
|
|
726 | my $init = shift; |
|
|
727 | |
|
|
728 | # rcv will create the actual port |
|
|
729 | local $SELF = "$NODE#$port"; |
|
|
730 | eval { |
|
|
731 | &{ load_func $init } |
280 | }; |
732 | }; |
|
|
733 | _self_die if $@; |
|
|
734 | } |
281 | |
735 | |
282 | =cut |
736 | sub spawn(@) { |
|
|
737 | my ($nodeid, undef) = split /#/, shift, 2; |
283 | |
738 | |
284 | sub port(;&) { |
|
|
285 | my $id = "$UNIQ." . $ID++; |
739 | my $id = "$RUNIQ." . $ID++; |
286 | my $port = "$NODE#$id"; |
|
|
287 | |
740 | |
288 | if (@_) { |
741 | $_[0] =~ /::/ |
289 | my $cb = shift; |
742 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
290 | $PORT{$id} = sub { |
743 | |
291 | local $SELF = $port; |
744 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
292 | eval { |
745 | |
293 | &$cb |
746 | "$nodeid#$id" |
294 | and kil $id; |
747 | } |
295 | }; |
748 | |
296 | _self_die if $@; |
749 | =item after $timeout, @msg |
|
|
750 | |
|
|
751 | =item after $timeout, $callback |
|
|
752 | |
|
|
753 | Either sends the given message, or call the given callback, after the |
|
|
754 | specified number of seconds. |
|
|
755 | |
|
|
756 | This is simply a utility function that comes in handy at times - the |
|
|
757 | AnyEvent::MP author is not convinced of the wisdom of having it, though, |
|
|
758 | so it may go away in the future. |
|
|
759 | |
|
|
760 | =cut |
|
|
761 | |
|
|
762 | sub after($@) { |
|
|
763 | my ($timeout, @action) = @_; |
|
|
764 | |
|
|
765 | my $t; $t = AE::timer $timeout, 0, sub { |
|
|
766 | undef $t; |
|
|
767 | ref $action[0] |
|
|
768 | ? $action[0]() |
|
|
769 | : snd @action; |
|
|
770 | }; |
|
|
771 | } |
|
|
772 | |
|
|
773 | =item cal $port, @msg, $callback[, $timeout] |
|
|
774 | |
|
|
775 | A simple form of RPC - sends a message to the given C<$port> with the |
|
|
776 | given contents (C<@msg>), but adds a reply port to the message. |
|
|
777 | |
|
|
778 | The reply port is created temporarily just for the purpose of receiving |
|
|
779 | the reply, and will be C<kil>ed when no longer needed. |
|
|
780 | |
|
|
781 | A reply message sent to the port is passed to the C<$callback> as-is. |
|
|
782 | |
|
|
783 | If an optional time-out (in seconds) is given and it is not C<undef>, |
|
|
784 | then the callback will be called without any arguments after the time-out |
|
|
785 | elapsed and the port is C<kil>ed. |
|
|
786 | |
|
|
787 | If no time-out is given (or it is C<undef>), then the local port will |
|
|
788 | monitor the remote port instead, so it eventually gets cleaned-up. |
|
|
789 | |
|
|
790 | Currently this function returns the temporary port, but this "feature" |
|
|
791 | might go in future versions unless you can make a convincing case that |
|
|
792 | this is indeed useful for something. |
|
|
793 | |
|
|
794 | =cut |
|
|
795 | |
|
|
796 | sub cal(@) { |
|
|
797 | my $timeout = ref $_[-1] ? undef : pop; |
|
|
798 | my $cb = pop; |
|
|
799 | |
|
|
800 | my $port = port { |
|
|
801 | undef $timeout; |
|
|
802 | kil $SELF; |
|
|
803 | &$cb; |
|
|
804 | }; |
|
|
805 | |
|
|
806 | if (defined $timeout) { |
|
|
807 | $timeout = AE::timer $timeout, 0, sub { |
|
|
808 | undef $timeout; |
|
|
809 | kil $port; |
|
|
810 | $cb->(); |
297 | }; |
811 | }; |
298 | } else { |
812 | } else { |
299 | my $self = bless { |
813 | mon $_[0], sub { |
300 | id => "$NODE#$id", |
814 | kil $port; |
301 | }, "AnyEvent::MP::Port"; |
815 | $cb->(); |
302 | |
|
|
303 | $PORT_DATA{$id} = $self; |
|
|
304 | $PORT{$id} = sub { |
|
|
305 | local $SELF = $port; |
|
|
306 | |
|
|
307 | eval { |
|
|
308 | for (@{ $self->{rc0}{$_[0]} }) { |
|
|
309 | $_ && &{$_->[0]} |
|
|
310 | && undef $_; |
|
|
311 | } |
|
|
312 | |
|
|
313 | for (@{ $self->{rcv}{$_[0]} }) { |
|
|
314 | $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1] |
|
|
315 | && &{$_->[0]} |
|
|
316 | && undef $_; |
|
|
317 | } |
|
|
318 | |
|
|
319 | for (@{ $self->{any} }) { |
|
|
320 | $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1] |
|
|
321 | && &{$_->[0]} |
|
|
322 | && undef $_; |
|
|
323 | } |
|
|
324 | }; |
|
|
325 | _self_die if $@; |
|
|
326 | }; |
816 | }; |
327 | } |
817 | } |
328 | |
818 | |
|
|
819 | push @_, $port; |
|
|
820 | &snd; |
|
|
821 | |
329 | $port |
822 | $port |
330 | } |
823 | } |
331 | |
824 | |
332 | =item reg $portid, $name |
|
|
333 | |
|
|
334 | Registers the given port under the name C<$name>. If the name already |
|
|
335 | exists it is replaced. |
|
|
336 | |
|
|
337 | A port can only be registered under one well known name. |
|
|
338 | |
|
|
339 | A port automatically becomes unregistered when it is killed. |
|
|
340 | |
|
|
341 | =cut |
|
|
342 | |
|
|
343 | sub reg(@) { |
|
|
344 | my ($portid, $name) = @_; |
|
|
345 | |
|
|
346 | $REG{$name} = $portid; |
|
|
347 | } |
|
|
348 | |
|
|
349 | =item rcv $portid, tagstring => $callback->(@msg), ... |
|
|
350 | |
|
|
351 | =item rcv $portid, $smartmatch => $callback->(@msg), ... |
|
|
352 | |
|
|
353 | =item rcv $portid, [$smartmatch...] => $callback->(@msg), ... |
|
|
354 | |
|
|
355 | Register callbacks to be called on matching messages on the given port. |
|
|
356 | |
|
|
357 | The callback has to return a true value when its work is done, after |
|
|
358 | which is will be removed, or a false value in which case it will stay |
|
|
359 | registered. |
|
|
360 | |
|
|
361 | The global C<$SELF> (exported by this module) contains C<$portid> while |
|
|
362 | executing the callback. |
|
|
363 | |
|
|
364 | Runtime errors wdurign callback execution will result in the port being |
|
|
365 | C<kil>ed. |
|
|
366 | |
|
|
367 | If the match is an array reference, then it will be matched against the |
|
|
368 | first elements of the message, otherwise only the first element is being |
|
|
369 | matched. |
|
|
370 | |
|
|
371 | Any element in the match that is specified as C<_any_> (a function |
|
|
372 | exported by this module) matches any single element of the message. |
|
|
373 | |
|
|
374 | While not required, it is highly recommended that the first matching |
|
|
375 | element is a string identifying the message. The one-string-only match is |
|
|
376 | also the most efficient match (by far). |
|
|
377 | |
|
|
378 | =cut |
|
|
379 | |
|
|
380 | sub rcv($@) { |
|
|
381 | my ($noderef, $port) = split /#/, shift, 2; |
|
|
382 | |
|
|
383 | ($NODE{$noderef} || add_node $noderef) == $NODE{""} |
|
|
384 | or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught"; |
|
|
385 | |
|
|
386 | my $self = $PORT_DATA{$port} |
|
|
387 | or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught"; |
|
|
388 | |
|
|
389 | "AnyEvent::MP::Port" eq ref $self |
|
|
390 | or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught"; |
|
|
391 | |
|
|
392 | while (@_) { |
|
|
393 | my ($match, $cb) = splice @_, 0, 2; |
|
|
394 | |
|
|
395 | if (!ref $match) { |
|
|
396 | push @{ $self->{rc0}{$match} }, [$cb]; |
|
|
397 | } elsif (("ARRAY" eq ref $match && !ref $match->[0])) { |
|
|
398 | my ($type, @match) = @$match; |
|
|
399 | @match |
|
|
400 | ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match] |
|
|
401 | : push @{ $self->{rc0}{$match->[0]} }, [$cb]; |
|
|
402 | } else { |
|
|
403 | push @{ $self->{any} }, [$cb, $match]; |
|
|
404 | } |
|
|
405 | } |
|
|
406 | } |
|
|
407 | |
|
|
408 | =item $closure = psub { BLOCK } |
|
|
409 | |
|
|
410 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
|
|
411 | closure is executed, sets up the environment in the same way as in C<rcv> |
|
|
412 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
|
|
413 | |
|
|
414 | This is useful when you register callbacks from C<rcv> callbacks: |
|
|
415 | |
|
|
416 | rcv delayed_reply => sub { |
|
|
417 | my ($delay, @reply) = @_; |
|
|
418 | my $timer = AE::timer $delay, 0, psub { |
|
|
419 | snd @reply, $SELF; |
|
|
420 | }; |
|
|
421 | }; |
|
|
422 | |
|
|
423 | =cut |
|
|
424 | |
|
|
425 | sub psub(&) { |
|
|
426 | my $cb = shift; |
|
|
427 | |
|
|
428 | my $port = $SELF |
|
|
429 | or Carp::croak "psub can only be called from within rcv or psub callbacks, not"; |
|
|
430 | |
|
|
431 | sub { |
|
|
432 | local $SELF = $port; |
|
|
433 | |
|
|
434 | if (wantarray) { |
|
|
435 | my @res = eval { &$cb }; |
|
|
436 | _self_die if $@; |
|
|
437 | @res |
|
|
438 | } else { |
|
|
439 | my $res = eval { &$cb }; |
|
|
440 | _self_die if $@; |
|
|
441 | $res |
|
|
442 | } |
|
|
443 | } |
|
|
444 | } |
|
|
445 | |
|
|
446 | =back |
825 | =back |
447 | |
826 | |
448 | =head1 FUNCTIONS FOR NODES |
827 | =head1 AnyEvent::MP vs. Distributed Erlang |
|
|
828 | |
|
|
829 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
|
|
830 | == aemp node, Erlang process == aemp port), so many of the documents and |
|
|
831 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
|
|
832 | sample: |
|
|
833 | |
|
|
834 | http://www.erlang.se/doc/programming_rules.shtml |
|
|
835 | http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
|
|
836 | http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6 |
|
|
837 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
|
|
838 | |
|
|
839 | Despite the similarities, there are also some important differences: |
449 | |
840 | |
450 | =over 4 |
841 | =over 4 |
451 | |
842 | |
452 | =item become_public endpoint... |
843 | =item * Node IDs are arbitrary strings in AEMP. |
453 | |
844 | |
454 | Tells the node to become a public node, i.e. reachable from other nodes. |
845 | Erlang relies on special naming and DNS to work everywhere in the same |
|
|
846 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
|
|
847 | configuration or DNS), and possibly the addresses of some seed nodes, but |
|
|
848 | will otherwise discover other nodes (and their IDs) itself. |
455 | |
849 | |
456 | If no arguments are given, or the first argument is C<undef>, then |
850 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
457 | AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the |
851 | uses "local ports are like remote ports". |
458 | local nodename resolves to. |
|
|
459 | |
852 | |
460 | Otherwise the first argument must be an array-reference with transport |
853 | The failure modes for local ports are quite different (runtime errors |
461 | endpoints ("ip:port", "hostname:port") or port numbers (in which case the |
854 | only) then for remote ports - when a local port dies, you I<know> it dies, |
462 | local nodename is used as hostname). The endpoints are all resolved and |
855 | when a connection to another node dies, you know nothing about the other |
463 | will become the node reference. |
856 | port. |
464 | |
857 | |
465 | =cut |
858 | Erlang pretends remote ports are as reliable as local ports, even when |
|
|
859 | they are not. |
|
|
860 | |
|
|
861 | AEMP encourages a "treat remote ports differently" philosophy, with local |
|
|
862 | ports being the special case/exception, where transport errors cannot |
|
|
863 | occur. |
|
|
864 | |
|
|
865 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
|
|
866 | |
|
|
867 | Erlang uses processes that selectively receive messages, and therefore |
|
|
868 | needs a queue. AEMP is event based, queuing messages would serve no |
|
|
869 | useful purpose. For the same reason the pattern-matching abilities of |
|
|
870 | AnyEvent::MP are more limited, as there is little need to be able to |
|
|
871 | filter messages without dequeuing them. |
|
|
872 | |
|
|
873 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
|
|
874 | |
|
|
875 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
|
|
876 | |
|
|
877 | Sending messages in Erlang is synchronous and blocks the process (and |
|
|
878 | so does not need a queue that can overflow). AEMP sends are immediate, |
|
|
879 | connection establishment is handled in the background. |
|
|
880 | |
|
|
881 | =item * Erlang suffers from silent message loss, AEMP does not. |
|
|
882 | |
|
|
883 | Erlang implements few guarantees on messages delivery - messages can get |
|
|
884 | lost without any of the processes realising it (i.e. you send messages a, |
|
|
885 | b, and c, and the other side only receives messages a and c). |
|
|
886 | |
|
|
887 | AEMP guarantees correct ordering, and the guarantee that after one message |
|
|
888 | is lost, all following ones sent to the same port are lost as well, until |
|
|
889 | monitoring raises an error, so there are no silent "holes" in the message |
|
|
890 | sequence. |
|
|
891 | |
|
|
892 | =item * Erlang can send messages to the wrong port, AEMP does not. |
|
|
893 | |
|
|
894 | In Erlang it is quite likely that a node that restarts reuses a process ID |
|
|
895 | known to other nodes for a completely different process, causing messages |
|
|
896 | destined for that process to end up in an unrelated process. |
|
|
897 | |
|
|
898 | AEMP never reuses port IDs, so old messages or old port IDs floating |
|
|
899 | around in the network will not be sent to an unrelated port. |
|
|
900 | |
|
|
901 | =item * Erlang uses unprotected connections, AEMP uses secure |
|
|
902 | authentication and can use TLS. |
|
|
903 | |
|
|
904 | AEMP can use a proven protocol - TLS - to protect connections and |
|
|
905 | securely authenticate nodes. |
|
|
906 | |
|
|
907 | =item * The AEMP protocol is optimised for both text-based and binary |
|
|
908 | communications. |
|
|
909 | |
|
|
910 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
|
|
911 | language independent text-only protocols (good for debugging) and binary, |
|
|
912 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
|
|
913 | used, the protocol is actually completely text-based. |
|
|
914 | |
|
|
915 | It has also been carefully designed to be implementable in other languages |
|
|
916 | with a minimum of work while gracefully degrading functionality to make the |
|
|
917 | protocol simple. |
|
|
918 | |
|
|
919 | =item * AEMP has more flexible monitoring options than Erlang. |
|
|
920 | |
|
|
921 | In Erlang, you can chose to receive I<all> exit signals as messages |
|
|
922 | or I<none>, there is no in-between, so monitoring single processes is |
|
|
923 | difficult to implement. Monitoring in AEMP is more flexible than in |
|
|
924 | Erlang, as one can choose between automatic kill, exit message or callback |
|
|
925 | on a per-process basis. |
|
|
926 | |
|
|
927 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
|
|
928 | |
|
|
929 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
|
|
930 | same way as linking is (except linking is unreliable in Erlang). |
|
|
931 | |
|
|
932 | In AEMP, you don't "look up" registered port names or send to named ports |
|
|
933 | that might or might not be persistent. Instead, you normally spawn a port |
|
|
934 | on the remote node. The init function monitors you, and you monitor the |
|
|
935 | remote port. Since both monitors are local to the node, they are much more |
|
|
936 | reliable (no need for C<spawn_link>). |
|
|
937 | |
|
|
938 | This also saves round-trips and avoids sending messages to the wrong port |
|
|
939 | (hard to do in Erlang). |
466 | |
940 | |
467 | =back |
941 | =back |
468 | |
942 | |
469 | =head1 NODE MESSAGES |
943 | =head1 RATIONALE |
470 | |
|
|
471 | Nodes understand the following messages sent to them. Many of them take |
|
|
472 | arguments called C<@reply>, which will simply be used to compose a reply |
|
|
473 | message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and |
|
|
474 | the remaining arguments are simply the message data. |
|
|
475 | |
944 | |
476 | =over 4 |
945 | =over 4 |
477 | |
946 | |
478 | =cut |
947 | =item Why strings for port and node IDs, why not objects? |
479 | |
948 | |
480 | =item lookup => $name, @reply |
949 | We considered "objects", but found that the actual number of methods |
|
|
950 | that can be called are quite low. Since port and node IDs travel over |
|
|
951 | the network frequently, the serialising/deserialising would add lots of |
|
|
952 | overhead, as well as having to keep a proxy object everywhere. |
481 | |
953 | |
482 | Replies with the port ID of the specified well-known port, or C<undef>. |
954 | Strings can easily be printed, easily serialised etc. and need no special |
|
|
955 | procedures to be "valid". |
483 | |
956 | |
484 | =item devnull => ... |
957 | And as a result, a port with just a default receiver consists of a single |
|
|
958 | closure stored in a global hash - it can't become much cheaper. |
485 | |
959 | |
486 | Generic data sink/CPU heat conversion. |
960 | =item Why favour JSON, why not a real serialising format such as Storable? |
487 | |
961 | |
488 | =item relay => $port, @msg |
962 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
|
|
963 | format, but currently there is no way to make a node use Storable by |
|
|
964 | default (although all nodes will accept it). |
489 | |
965 | |
490 | Simply forwards the message to the given port. |
966 | The default framing protocol is JSON because a) JSON::XS is many times |
|
|
967 | faster for small messages and b) most importantly, after years of |
|
|
968 | experience we found that object serialisation is causing more problems |
|
|
969 | than it solves: Just like function calls, objects simply do not travel |
|
|
970 | easily over the network, mostly because they will always be a copy, so you |
|
|
971 | always have to re-think your design. |
491 | |
972 | |
492 | =item eval => $string[ @reply] |
973 | Keeping your messages simple, concentrating on data structures rather than |
493 | |
974 | objects, will keep your messages clean, tidy and efficient. |
494 | Evaluates the given string. If C<@reply> is given, then a message of the |
|
|
495 | form C<@reply, $@, @evalres> is sent. |
|
|
496 | |
|
|
497 | Example: crash another node. |
|
|
498 | |
|
|
499 | snd $othernode, eval => "exit"; |
|
|
500 | |
|
|
501 | =item time => @reply |
|
|
502 | |
|
|
503 | Replies the the current node time to C<@reply>. |
|
|
504 | |
|
|
505 | Example: tell the current node to send the current time to C<$myport> in a |
|
|
506 | C<timereply> message. |
|
|
507 | |
|
|
508 | snd $NODE, time => $myport, timereply => 1, 2; |
|
|
509 | # => snd $myport, timereply => 1, 2, <time> |
|
|
510 | |
975 | |
511 | =back |
976 | =back |
512 | |
977 | |
513 | =head1 SEE ALSO |
978 | =head1 SEE ALSO |
|
|
979 | |
|
|
980 | L<AnyEvent::MP::Intro> - a gentle introduction. |
|
|
981 | |
|
|
982 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
|
|
983 | |
|
|
984 | L<AnyEvent::MP::Global> - network maintenance and port groups, to find |
|
|
985 | your applications. |
|
|
986 | |
|
|
987 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
|
|
988 | |
|
|
989 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
|
|
990 | all nodes. |
514 | |
991 | |
515 | L<AnyEvent>. |
992 | L<AnyEvent>. |
516 | |
993 | |
517 | =head1 AUTHOR |
994 | =head1 AUTHOR |
518 | |
995 | |