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 # returns this node identifier |
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10 | $NODE # contains this node identifier |
9 | $NODE # contains this node's node ID |
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10 | NODE # returns this node's node ID |
11 | |
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 |
12 | 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; |
13 | |
23 | |
14 | rcv $port, smartmatch => $cb->($port, @msg); |
24 | # creating/using ports, the simple way |
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25 | my $simple_port = port { my @msg = @_ }; |
15 | |
26 | |
16 | # examples: |
27 | # creating/using ports, tagged message matching |
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28 | my $port = port; |
17 | rcv $port2, ping => sub { snd $_[0], "pong"; 0 }; |
29 | rcv $port, ping => sub { snd $_[0], "pong" }; |
18 | rcv $port1, pong => sub { warn "pong received\n" }; |
30 | rcv $port, pong => sub { warn "pong received\n" }; |
19 | snd $port2, ping => $port1; |
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20 | |
31 | |
21 | # more, smarter, matches (_any_ is exported by this module) |
32 | # create a port on another node |
22 | rcv $port, [child_died => $pid] => sub { ... |
33 | my $port = spawn $node, $initfunc, @initdata; |
23 | 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 $port, $cb->(@msg) # callback is invoked on death |
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41 | mon $port, $localport # kill localport on abnormal death |
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42 | mon $port, $localport, @msg # send message on death |
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43 | |
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44 | # temporarily execute code in port context |
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45 | peval $port, sub { die "kill the port!" }; |
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46 | |
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47 | # execute callbacks in $SELF port context |
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48 | my $timer = AE::timer 1, 0, psub { |
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49 | die "kill the port, delayed"; |
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50 | }; |
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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. |
24 | |
59 | |
25 | =head1 DESCRIPTION |
60 | =head1 DESCRIPTION |
26 | |
61 | |
27 | This module (-family) implements a simple message passing framework. |
62 | This module (-family) implements a simple message passing framework. |
28 | |
63 | |
29 | Despite its simplicity, you can securely message other processes running |
64 | Despite its simplicity, you can securely message other processes running |
30 | on the same or other hosts. |
65 | on the same or other hosts, and you can supervise entities remotely. |
31 | |
66 | |
32 | At the moment, this module family is severly brokena nd underdocumented, |
67 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
33 | so do not use. This was uploaded mainly to resreve the CPAN namespace - |
68 | manual page and the examples under F<eg/>. |
34 | stay tuned! |
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35 | |
69 | |
36 | =head1 CONCEPTS |
70 | =head1 CONCEPTS |
37 | |
71 | |
38 | =over 4 |
72 | =over 4 |
39 | |
73 | |
40 | =item port |
74 | =item port |
41 | |
75 | |
42 | 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 |
43 | you can register C<rcv> handlers with. All C<rcv> handlers will receive |
77 | messages to (with the C<snd> function). |
44 | messages they match, messages will not be queued. |
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45 | |
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 | |
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83 | Ports are represented by (printable) strings called "port IDs". |
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84 | |
46 | =item port id - C<noderef#portname> |
85 | =item port ID - C<nodeid#portname> |
47 | |
86 | |
48 | A port id is always the noderef, a hash-mark (C<#>) as separator, followed |
87 | A port ID is the concatenation of a node ID, a hash-mark (C<#>) |
49 | by 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). |
50 | |
90 | |
51 | =item node |
91 | =item node |
52 | |
92 | |
53 | A node is a single process containing at least one port - the node |
93 | A node is a single process containing at least one port - the node port, |
54 | port. You can send messages to node ports to let them create new ports, |
94 | which enables nodes to manage each other remotely, and to create new |
55 | among other things. |
95 | ports. |
56 | |
96 | |
57 | Initially, nodes are either private (single-process only) or hidden |
97 | Nodes are either public (have one or more listening ports) or private |
58 | (connected to a master node only). Only when they epxlicitly "become |
98 | (no listening ports). Private nodes cannot talk to other private nodes |
59 | public" can you send them messages from unrelated other nodes. |
99 | currently, but all nodes can talk to public nodes. |
60 | |
100 | |
61 | =item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> |
101 | Nodes is represented by (printable) strings called "node IDs". |
62 | |
102 | |
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103 | =item node ID - C<[A-Za-z0-9_\-.:]*> |
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104 | |
63 | A noderef is a string that either uniquely identifies a given node (for |
105 | A node ID is a string that uniquely identifies the node within a |
64 | private and hidden nodes), or contains a recipe on how to reach a given |
106 | network. Depending on the configuration used, node IDs can look like a |
65 | node (for public nodes). |
107 | hostname, a hostname and a port, or a random string. AnyEvent::MP itself |
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108 | doesn't interpret node IDs in any way except to uniquely identify a node. |
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109 | |
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110 | =item binds - C<ip:port> |
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111 | |
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112 | Nodes can only talk to each other by creating some kind of connection to |
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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 | |
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116 | Currently, only standard C<ip:port> specifications can be used, which |
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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. |
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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 | |
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149 | =item seed IDs - C<host:port> |
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150 | |
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151 | Seed IDs are transport endpoint(s) (usually a hostname/IP address and a |
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152 | TCP port) of nodes that should be used as seed nodes. |
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153 | |
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154 | =item global nodes |
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155 | |
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156 | An AEMP network needs a discovery service - nodes need to know how to |
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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). |
66 | |
170 | |
67 | =back |
171 | =back |
68 | |
172 | |
69 | =head1 VARIABLES/FUNCTIONS |
173 | =head1 VARIABLES/FUNCTIONS |
70 | |
174 | |
… | |
… | |
72 | |
176 | |
73 | =cut |
177 | =cut |
74 | |
178 | |
75 | package AnyEvent::MP; |
179 | package AnyEvent::MP; |
76 | |
180 | |
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181 | use AnyEvent::MP::Config (); |
77 | use AnyEvent::MP::Base; |
182 | use AnyEvent::MP::Kernel; |
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183 | use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID); |
78 | |
184 | |
79 | use common::sense; |
185 | use common::sense; |
80 | |
186 | |
81 | use Carp (); |
187 | use Carp (); |
82 | |
188 | |
83 | use AE (); |
189 | use AE (); |
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190 | use Guard (); |
84 | |
191 | |
85 | use base "Exporter"; |
192 | use base "Exporter"; |
86 | |
193 | |
87 | our $VERSION = '0.02'; |
194 | our $VERSION = $AnyEvent::MP::Config::VERSION; |
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195 | |
88 | our @EXPORT = qw( |
196 | our @EXPORT = qw( |
89 | NODE $NODE $PORT snd rcv _any_ |
197 | NODE $NODE *SELF node_of after |
90 | create_port create_port_on |
198 | configure |
91 | become_slave become_public |
199 | snd rcv mon mon_guard kil psub peval spawn cal |
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200 | port |
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201 | db_set db_del db_reg |
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202 | db_mon db_family db_keys db_values |
92 | ); |
203 | ); |
93 | |
204 | |
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205 | our $SELF; |
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206 | |
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207 | sub _self_die() { |
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208 | my $msg = $@; |
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209 | $msg =~ s/\n+$// unless ref $msg; |
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210 | kil $SELF, die => $msg; |
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211 | } |
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212 | |
94 | =item NODE / $NODE |
213 | =item $thisnode = NODE / $NODE |
95 | |
214 | |
96 | The C<NODE ()> function and the C<$NODE> variable contain the noderef of |
215 | The C<NODE> function returns, and the C<$NODE> variable contains, the node |
97 | the local node. The value is initialised by a call to C<become_public> or |
216 | ID of the node running in the current process. This value is initialised by |
98 | C<become_slave>, after which all local port identifiers become invalid. |
217 | a call to C<configure>. |
99 | |
218 | |
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219 | =item $nodeid = node_of $port |
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220 | |
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221 | Extracts and returns the node ID from a port ID or a node ID. |
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222 | |
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223 | =item configure $profile, key => value... |
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224 | |
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225 | =item configure key => value... |
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226 | |
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227 | Before a node can talk to other nodes on the network (i.e. enter |
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228 | "distributed mode") it has to configure itself - the minimum a node needs |
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229 | to know is its own name, and optionally it should know the addresses of |
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230 | some other nodes in the network to discover other nodes. |
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231 | |
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232 | This function configures a node - it must be called exactly once (or |
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233 | never) before calling other AnyEvent::MP functions. |
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234 | |
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235 | The key/value pairs are basically the same ones as documented for the |
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236 | F<aemp> command line utility (sans the set/del prefix), with these additions: |
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237 | |
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238 | =over 4 |
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239 | |
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240 | =item norc => $boolean (default false) |
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241 | |
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242 | If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not> |
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243 | be consulted - all configuraiton options must be specified in the |
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244 | C<configure> call. |
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245 | |
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246 | =item force => $boolean (default false) |
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247 | |
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248 | IF true, then the values specified in the C<configure> will take |
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249 | precedence over any values configured via the rc file. The default is for |
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250 | the rc file to override any options specified in the program. |
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251 | |
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252 | =item secure => $pass->($nodeid) |
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253 | |
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254 | In addition to specifying a boolean, you can specify a code reference that |
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255 | is called for every remote execution attempt - the execution request is |
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256 | granted iff the callback returns a true value. |
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257 | |
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258 | See F<semp setsecure> for more info. |
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259 | |
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260 | =back |
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261 | |
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262 | =over 4 |
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263 | |
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264 | =item step 1, gathering configuration from profiles |
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265 | |
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266 | The function first looks up a profile in the aemp configuration (see the |
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267 | L<aemp> commandline utility). The profile name can be specified via the |
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268 | named C<profile> parameter or can simply be the first parameter). If it is |
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269 | missing, then the nodename (F<uname -n>) will be used as profile name. |
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270 | |
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271 | The profile data is then gathered as follows: |
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272 | |
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273 | First, all remaining key => value pairs (all of which are conveniently |
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274 | undocumented at the moment) will be interpreted as configuration |
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275 | data. Then they will be overwritten by any values specified in the global |
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276 | default configuration (see the F<aemp> utility), then the chain of |
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277 | profiles chosen by the profile name (and any C<parent> attributes). |
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278 | |
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279 | That means that the values specified in the profile have highest priority |
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280 | and the values specified directly via C<configure> have lowest priority, |
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281 | and can only be used to specify defaults. |
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282 | |
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283 | If the profile specifies a node ID, then this will become the node ID of |
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284 | this process. If not, then the profile name will be used as node ID, with |
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285 | a unique randoms tring (C</%u>) appended. |
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286 | |
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287 | The node ID can contain some C<%> sequences that are expanded: C<%n> |
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288 | is expanded to the local nodename, C<%u> is replaced by a random |
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289 | strign to make the node unique. For example, the F<aemp> commandline |
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290 | utility uses C<aemp/%n/%u> as nodename, which might expand to |
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291 | C<aemp/cerebro/ZQDGSIkRhEZQDGSIkRhE>. |
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292 | |
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293 | =item step 2, bind listener sockets |
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294 | |
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295 | The next step is to look up the binds in the profile, followed by binding |
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296 | aemp protocol listeners on all binds specified (it is possible and valid |
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297 | to have no binds, meaning that the node cannot be contacted form the |
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298 | outside. This means the node cannot talk to other nodes that also have no |
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299 | binds, but it can still talk to all "normal" nodes). |
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300 | |
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301 | If the profile does not specify a binds list, then a default of C<*> is |
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302 | used, meaning the node will bind on a dynamically-assigned port on every |
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303 | local IP address it finds. |
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304 | |
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305 | =item step 3, connect to seed nodes |
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306 | |
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307 | As the last step, the seed ID list from the profile is passed to the |
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308 | L<AnyEvent::MP::Global> module, which will then use it to keep |
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309 | connectivity with at least one node at any point in time. |
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310 | |
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311 | =back |
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312 | |
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313 | Example: become a distributed node using the local node name as profile. |
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314 | This should be the most common form of invocation for "daemon"-type nodes. |
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315 | |
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316 | configure |
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317 | |
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318 | Example: become a semi-anonymous node. This form is often used for |
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319 | commandline clients. |
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320 | |
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321 | configure nodeid => "myscript/%n/%u"; |
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322 | |
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323 | Example: configure a node using a profile called seed, which is suitable |
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324 | for a seed node as it binds on all local addresses on a fixed port (4040, |
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325 | customary for aemp). |
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326 | |
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327 | # use the aemp commandline utility |
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328 | # aemp profile seed binds '*:4040' |
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329 | |
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330 | # then use it |
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331 | configure profile => "seed"; |
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332 | |
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333 | # or simply use aemp from the shell again: |
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334 | # aemp run profile seed |
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335 | |
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336 | # or provide a nicer-to-remember nodeid |
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337 | # aemp run profile seed nodeid "$(hostname)" |
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338 | |
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339 | =item $SELF |
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340 | |
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341 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
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342 | blocks. |
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343 | |
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344 | =item *SELF, SELF, %SELF, @SELF... |
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345 | |
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346 | Due to some quirks in how perl exports variables, it is impossible to |
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347 | just export C<$SELF>, all the symbols named C<SELF> are exported by this |
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348 | module, but only C<$SELF> is currently used. |
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349 | |
100 | =item snd $portid, type => @data |
350 | =item snd $port, type => @data |
101 | |
351 | |
102 | =item snd $portid, @msg |
352 | =item snd $port, @msg |
103 | |
353 | |
104 | Send the given message to the given port ID, which can identify either |
354 | Send the given message to the given port, which can identify either a |
105 | a local or a remote port, and can be either a string or soemthignt hat |
355 | local or a remote port, and must be a port ID. |
106 | stringifies a sa port ID (such as a port object :). |
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107 | |
356 | |
108 | While the message can be about anything, it is highly recommended to use a |
357 | While the message can be almost anything, it is highly recommended to |
109 | string as first element (a portid, or some word that indicates a request |
358 | use a string as first element (a port ID, or some word that indicates a |
110 | type etc.). |
359 | request type etc.) and to consist if only simple perl values (scalars, |
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360 | arrays, hashes) - if you think you need to pass an object, think again. |
111 | |
361 | |
112 | The message data effectively becomes read-only after a call to this |
362 | The message data logically becomes read-only after a call to this |
113 | function: modifying any argument is not allowed and can cause many |
363 | function: modifying any argument (or values referenced by them) is |
114 | problems. |
364 | forbidden, as there can be considerable time between the call to C<snd> |
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365 | and the time the message is actually being serialised - in fact, it might |
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366 | never be copied as within the same process it is simply handed to the |
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367 | receiving port. |
115 | |
368 | |
116 | The type of data you can transfer depends on the transport protocol: when |
369 | The type of data you can transfer depends on the transport protocol: when |
117 | JSON is used, then only strings, numbers and arrays and hashes consisting |
370 | JSON is used, then only strings, numbers and arrays and hashes consisting |
118 | of those are allowed (no objects). When Storable is used, then anything |
371 | of those are allowed (no objects). When Storable is used, then anything |
119 | that Storable can serialise and deserialise is allowed, and for the local |
372 | that Storable can serialise and deserialise is allowed, and for the local |
120 | node, anything can be passed. |
373 | node, anything can be passed. Best rely only on the common denominator of |
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374 | these. |
121 | |
375 | |
122 | =item $local_port = create_port |
376 | =item $local_port = port |
123 | |
377 | |
124 | Create a new local port object. See the next section for allowed methods. |
378 | Create a new local port object and returns its port ID. Initially it has |
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379 | no callbacks set and will throw an error when it receives messages. |
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380 | |
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381 | =item $local_port = port { my @msg = @_ } |
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382 | |
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383 | Creates a new local port, and returns its ID. Semantically the same as |
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384 | creating a port and calling C<rcv $port, $callback> on it. |
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385 | |
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386 | The block will be called for every message received on the port, with the |
|
|
387 | global variable C<$SELF> set to the port ID. Runtime errors will cause the |
|
|
388 | port to be C<kil>ed. The message will be passed as-is, no extra argument |
|
|
389 | (i.e. no port ID) will be passed to the callback. |
|
|
390 | |
|
|
391 | If you want to stop/destroy the port, simply C<kil> it: |
|
|
392 | |
|
|
393 | my $port = port { |
|
|
394 | my @msg = @_; |
|
|
395 | ... |
|
|
396 | kil $SELF; |
|
|
397 | }; |
125 | |
398 | |
126 | =cut |
399 | =cut |
127 | |
400 | |
128 | sub create_port { |
401 | sub rcv($@); |
129 | my $id = "$AnyEvent::MP::Base::UNIQ." . ++$AnyEvent::MP::Base::ID; |
|
|
130 | |
402 | |
131 | my $self = bless { |
403 | sub _kilme { |
132 | id => "$NODE#$id", |
404 | die "received message on port without callback"; |
133 | names => [$id], |
405 | } |
134 | }, "AnyEvent::MP::Port"; |
|
|
135 | |
406 | |
136 | $AnyEvent::MP::Base::PORT{$id} = sub { |
407 | sub port(;&) { |
137 | unshift @_, $self; |
408 | my $id = $UNIQ . ++$ID; |
|
|
409 | my $port = "$NODE#$id"; |
138 | |
410 | |
139 | for (@{ $self->{rc0}{$_[1]} }) { |
411 | rcv $port, shift || \&_kilme; |
140 | $_ && &{$_->[0]} |
412 | |
141 | && undef $_; |
413 | $port |
|
|
414 | } |
|
|
415 | |
|
|
416 | =item rcv $local_port, $callback->(@msg) |
|
|
417 | |
|
|
418 | Replaces the default callback on the specified port. There is no way to |
|
|
419 | remove the default callback: use C<sub { }> to disable it, or better |
|
|
420 | C<kil> the port when it is no longer needed. |
|
|
421 | |
|
|
422 | The global C<$SELF> (exported by this module) contains C<$port> while |
|
|
423 | executing the callback. Runtime errors during callback execution will |
|
|
424 | result in the port being C<kil>ed. |
|
|
425 | |
|
|
426 | The default callback received all messages not matched by a more specific |
|
|
427 | C<tag> match. |
|
|
428 | |
|
|
429 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
|
|
430 | |
|
|
431 | Register (or replace) callbacks to be called on messages starting with the |
|
|
432 | given tag on the given port (and return the port), or unregister it (when |
|
|
433 | C<$callback> is C<$undef> or missing). There can only be one callback |
|
|
434 | registered for each tag. |
|
|
435 | |
|
|
436 | The original message will be passed to the callback, after the first |
|
|
437 | element (the tag) has been removed. The callback will use the same |
|
|
438 | environment as the default callback (see above). |
|
|
439 | |
|
|
440 | Example: create a port and bind receivers on it in one go. |
|
|
441 | |
|
|
442 | my $port = rcv port, |
|
|
443 | msg1 => sub { ... }, |
|
|
444 | msg2 => sub { ... }, |
|
|
445 | ; |
|
|
446 | |
|
|
447 | Example: create a port, bind receivers and send it in a message elsewhere |
|
|
448 | in one go: |
|
|
449 | |
|
|
450 | snd $otherport, reply => |
|
|
451 | rcv port, |
|
|
452 | msg1 => sub { ... }, |
|
|
453 | ... |
|
|
454 | ; |
|
|
455 | |
|
|
456 | Example: temporarily register a rcv callback for a tag matching some port |
|
|
457 | (e.g. for an rpc reply) and unregister it after a message was received. |
|
|
458 | |
|
|
459 | rcv $port, $otherport => sub { |
|
|
460 | my @reply = @_; |
|
|
461 | |
|
|
462 | rcv $SELF, $otherport; |
|
|
463 | }; |
|
|
464 | |
|
|
465 | =cut |
|
|
466 | |
|
|
467 | sub rcv($@) { |
|
|
468 | my $port = shift; |
|
|
469 | my ($nodeid, $portid) = split /#/, $port, 2; |
|
|
470 | |
|
|
471 | $NODE{$nodeid} == $NODE{""} |
|
|
472 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
|
|
473 | |
|
|
474 | while (@_) { |
|
|
475 | if (ref $_[0]) { |
|
|
476 | if (my $self = $PORT_DATA{$portid}) { |
|
|
477 | "AnyEvent::MP::Port" eq ref $self |
|
|
478 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
|
|
479 | |
|
|
480 | $self->[0] = shift; |
|
|
481 | } else { |
|
|
482 | my $cb = shift; |
|
|
483 | $PORT{$portid} = sub { |
|
|
484 | local $SELF = $port; |
|
|
485 | eval { &$cb }; _self_die if $@; |
|
|
486 | }; |
|
|
487 | } |
|
|
488 | } elsif (defined $_[0]) { |
|
|
489 | my $self = $PORT_DATA{$portid} ||= do { |
|
|
490 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
|
|
491 | |
|
|
492 | $PORT{$portid} = sub { |
|
|
493 | local $SELF = $port; |
|
|
494 | |
|
|
495 | if (my $cb = $self->[1]{$_[0]}) { |
|
|
496 | shift; |
|
|
497 | eval { &$cb }; _self_die if $@; |
|
|
498 | } else { |
|
|
499 | &{ $self->[0] }; |
|
|
500 | } |
|
|
501 | }; |
|
|
502 | |
|
|
503 | $self |
|
|
504 | }; |
|
|
505 | |
|
|
506 | "AnyEvent::MP::Port" eq ref $self |
|
|
507 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
|
|
508 | |
|
|
509 | my ($tag, $cb) = splice @_, 0, 2; |
|
|
510 | |
|
|
511 | if (defined $cb) { |
|
|
512 | $self->[1]{$tag} = $cb; |
|
|
513 | } else { |
|
|
514 | delete $self->[1]{$tag}; |
|
|
515 | } |
142 | } |
516 | } |
|
|
517 | } |
143 | |
518 | |
144 | for (@{ $self->{rcv}{$_[1]} }) { |
519 | $port |
145 | $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1] |
520 | } |
146 | && &{$_->[0]} |
|
|
147 | && undef $_; |
|
|
148 | } |
|
|
149 | |
521 | |
150 | for (@{ $self->{any} }) { |
522 | =item peval $port, $coderef[, @args] |
151 | $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1] |
523 | |
152 | && &{$_->[0]} |
524 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
153 | && undef $_; |
525 | when the code throews an exception the C<$port> will be killed. |
154 | } |
526 | |
|
|
527 | Any remaining args will be passed to the callback. Any return values will |
|
|
528 | be returned to the caller. |
|
|
529 | |
|
|
530 | This is useful when you temporarily want to execute code in the context of |
|
|
531 | a port. |
|
|
532 | |
|
|
533 | Example: create a port and run some initialisation code in it's context. |
|
|
534 | |
|
|
535 | my $port = port { ... }; |
|
|
536 | |
|
|
537 | peval $port, sub { |
|
|
538 | init |
|
|
539 | or die "unable to init"; |
155 | }; |
540 | }; |
156 | |
541 | |
157 | $self |
|
|
158 | } |
|
|
159 | |
|
|
160 | package AnyEvent::MP::Port; |
|
|
161 | |
|
|
162 | =back |
|
|
163 | |
|
|
164 | =head1 METHODS FOR PORT OBJECTS |
|
|
165 | |
|
|
166 | =over 4 |
|
|
167 | |
|
|
168 | =item "$port" |
|
|
169 | |
|
|
170 | A port object stringifies to its port ID, so can be used directly for |
|
|
171 | C<snd> operations. |
|
|
172 | |
|
|
173 | =cut |
542 | =cut |
174 | |
543 | |
175 | use overload |
544 | sub peval($$) { |
176 | '""' => sub { $_[0]{id} }, |
545 | local $SELF = shift; |
177 | fallback => 1; |
546 | my $cb = shift; |
178 | |
547 | |
179 | =item $port->rcv (type => $callback->($port, @msg)) |
548 | if (wantarray) { |
180 | |
549 | my @res = eval { &$cb }; |
181 | =item $port->rcv ($smartmatch => $callback->($port, @msg)) |
550 | _self_die if $@; |
182 | |
551 | @res |
183 | =item $port->rcv ([$smartmatch...] => $callback->($port, @msg)) |
|
|
184 | |
|
|
185 | Register a callback on the given port. |
|
|
186 | |
|
|
187 | The callback has to return a true value when its work is done, after |
|
|
188 | which is will be removed, or a false value in which case it will stay |
|
|
189 | registered. |
|
|
190 | |
|
|
191 | If the match is an array reference, then it will be matched against the |
|
|
192 | first elements of the message, otherwise only the first element is being |
|
|
193 | matched. |
|
|
194 | |
|
|
195 | Any element in the match that is specified as C<_any_> (a function |
|
|
196 | exported by this module) matches any single element of the message. |
|
|
197 | |
|
|
198 | While not required, it is highly recommended that the first matching |
|
|
199 | element is a string identifying the message. The one-string-only match is |
|
|
200 | also the most efficient match (by far). |
|
|
201 | |
|
|
202 | =cut |
|
|
203 | |
|
|
204 | sub rcv($@) { |
|
|
205 | my ($self, $match, $cb) = @_; |
|
|
206 | |
|
|
207 | if (!ref $match) { |
|
|
208 | push @{ $self->{rc0}{$match} }, [$cb]; |
|
|
209 | } elsif (("ARRAY" eq ref $match && !ref $match->[0])) { |
|
|
210 | my ($type, @match) = @$match; |
|
|
211 | @match |
|
|
212 | ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match] |
|
|
213 | : push @{ $self->{rc0}{$match->[0]} }, [$cb]; |
|
|
214 | } else { |
552 | } else { |
215 | push @{ $self->{any} }, [$cb, $match]; |
553 | my $res = eval { &$cb }; |
|
|
554 | _self_die if $@; |
|
|
555 | $res |
216 | } |
556 | } |
217 | } |
557 | } |
218 | |
558 | |
219 | =item $port->register ($name) |
559 | =item $closure = psub { BLOCK } |
220 | |
560 | |
221 | Registers the given port under the well known name C<$name>. If the name |
561 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
222 | already exists it is replaced. |
562 | closure is executed, sets up the environment in the same way as in C<rcv> |
|
|
563 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
223 | |
564 | |
224 | A port can only be registered under one well known name. |
565 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
|
|
566 | BLOCK }, @_ } >>. |
|
|
567 | |
|
|
568 | This is useful when you register callbacks from C<rcv> callbacks: |
|
|
569 | |
|
|
570 | rcv delayed_reply => sub { |
|
|
571 | my ($delay, @reply) = @_; |
|
|
572 | my $timer = AE::timer $delay, 0, psub { |
|
|
573 | snd @reply, $SELF; |
|
|
574 | }; |
|
|
575 | }; |
225 | |
576 | |
226 | =cut |
577 | =cut |
227 | |
578 | |
228 | sub register { |
579 | sub psub(&) { |
229 | my ($self, $name) = @_; |
580 | my $cb = shift; |
230 | |
581 | |
231 | $self->{wkname} = $name; |
582 | my $port = $SELF |
232 | $AnyEvent::MP::Base::WKP{$name} = "$self"; |
583 | or Carp::croak "psub can only be called from within rcv or psub callbacks, not"; |
|
|
584 | |
|
|
585 | sub { |
|
|
586 | local $SELF = $port; |
|
|
587 | |
|
|
588 | if (wantarray) { |
|
|
589 | my @res = eval { &$cb }; |
|
|
590 | _self_die if $@; |
|
|
591 | @res |
|
|
592 | } else { |
|
|
593 | my $res = eval { &$cb }; |
|
|
594 | _self_die if $@; |
|
|
595 | $res |
|
|
596 | } |
|
|
597 | } |
233 | } |
598 | } |
234 | |
599 | |
235 | =item $port->destroy |
600 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
236 | |
601 | |
237 | Explicitly destroy/remove/nuke/vaporise the port. |
602 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
238 | |
603 | |
239 | Ports are normally kept alive by there mere existance alone, and need to |
604 | =item $guard = mon $port # kill $SELF when $port dies |
240 | be destroyed explicitly. |
605 | |
|
|
606 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
|
|
607 | |
|
|
608 | Monitor the given port and do something when the port is killed or |
|
|
609 | messages to it were lost, and optionally return a guard that can be used |
|
|
610 | to stop monitoring again. |
|
|
611 | |
|
|
612 | In the first form (callback), the callback is simply called with any |
|
|
613 | number of C<@reason> elements (no @reason means that the port was deleted |
|
|
614 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
|
|
615 | C<eval> if unsure. |
|
|
616 | |
|
|
617 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
618 | will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on |
|
|
619 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
620 | port is killed with the same reason. |
|
|
621 | |
|
|
622 | The third form (kill self) is the same as the second form, except that |
|
|
623 | C<$rvport> defaults to C<$SELF>. |
|
|
624 | |
|
|
625 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
626 | C<snd>. |
|
|
627 | |
|
|
628 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
|
|
629 | alert was raised), they are removed and will not trigger again. |
|
|
630 | |
|
|
631 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
632 | a local port (or callback). The reason is that kill messages might get |
|
|
633 | lost, just like any other message. Another less obvious reason is that |
|
|
634 | even monitoring requests can get lost (for example, when the connection |
|
|
635 | to the other node goes down permanently). When monitoring a port locally |
|
|
636 | these problems do not exist. |
|
|
637 | |
|
|
638 | C<mon> effectively guarantees that, in the absence of hardware failures, |
|
|
639 | after starting the monitor, either all messages sent to the port will |
|
|
640 | arrive, or the monitoring action will be invoked after possible message |
|
|
641 | loss has been detected. No messages will be lost "in between" (after |
|
|
642 | the first lost message no further messages will be received by the |
|
|
643 | port). After the monitoring action was invoked, further messages might get |
|
|
644 | delivered again. |
|
|
645 | |
|
|
646 | Inter-host-connection timeouts and monitoring depend on the transport |
|
|
647 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
|
|
648 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
|
|
649 | non-idle connection, and usually around two hours for idle connections). |
|
|
650 | |
|
|
651 | This means that monitoring is good for program errors and cleaning up |
|
|
652 | stuff eventually, but they are no replacement for a timeout when you need |
|
|
653 | to ensure some maximum latency. |
|
|
654 | |
|
|
655 | Example: call a given callback when C<$port> is killed. |
|
|
656 | |
|
|
657 | mon $port, sub { warn "port died because of <@_>\n" }; |
|
|
658 | |
|
|
659 | Example: kill ourselves when C<$port> is killed abnormally. |
|
|
660 | |
|
|
661 | mon $port; |
|
|
662 | |
|
|
663 | Example: send us a restart message when another C<$port> is killed. |
|
|
664 | |
|
|
665 | mon $port, $self => "restart"; |
241 | |
666 | |
242 | =cut |
667 | =cut |
243 | |
668 | |
244 | sub destroy { |
669 | sub mon { |
245 | my ($self) = @_; |
670 | my ($nodeid, $port) = split /#/, shift, 2; |
246 | |
671 | |
247 | delete $AnyEvent::MP::Base::WKP{ $self->{wkname} }; |
672 | my $node = $NODE{$nodeid} || add_node $nodeid; |
248 | |
673 | |
249 | delete $AnyEvent::MP::Base::PORT{$_} |
674 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
250 | for @{ $self->{names} }; |
675 | |
|
|
676 | unless (ref $cb) { |
|
|
677 | if (@_) { |
|
|
678 | # send a kill info message |
|
|
679 | my (@msg) = ($cb, @_); |
|
|
680 | $cb = sub { snd @msg, @_ }; |
|
|
681 | } else { |
|
|
682 | # simply kill other port |
|
|
683 | my $port = $cb; |
|
|
684 | $cb = sub { kil $port, @_ if @_ }; |
|
|
685 | } |
|
|
686 | } |
|
|
687 | |
|
|
688 | $node->monitor ($port, $cb); |
|
|
689 | |
|
|
690 | defined wantarray |
|
|
691 | and ($cb += 0, Guard::guard { $node->unmonitor ($port, $cb) }) |
251 | } |
692 | } |
252 | |
693 | |
|
|
694 | =item $guard = mon_guard $port, $ref, $ref... |
|
|
695 | |
|
|
696 | Monitors the given C<$port> and keeps the passed references. When the port |
|
|
697 | is killed, the references will be freed. |
|
|
698 | |
|
|
699 | Optionally returns a guard that will stop the monitoring. |
|
|
700 | |
|
|
701 | This function is useful when you create e.g. timers or other watchers and |
|
|
702 | want to free them when the port gets killed (note the use of C<psub>): |
|
|
703 | |
|
|
704 | $port->rcv (start => sub { |
|
|
705 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub { |
|
|
706 | undef $timer if 0.9 < rand; |
|
|
707 | }); |
|
|
708 | }); |
|
|
709 | |
|
|
710 | =cut |
|
|
711 | |
|
|
712 | sub mon_guard { |
|
|
713 | my ($port, @refs) = @_; |
|
|
714 | |
|
|
715 | #TODO: mon-less form? |
|
|
716 | |
|
|
717 | mon $port, sub { 0 && @refs } |
|
|
718 | } |
|
|
719 | |
|
|
720 | =item kil $port[, @reason] |
|
|
721 | |
|
|
722 | Kill the specified port with the given C<@reason>. |
|
|
723 | |
|
|
724 | If no C<@reason> is specified, then the port is killed "normally" - |
|
|
725 | monitor callback will be invoked, but the kil will not cause linked ports |
|
|
726 | (C<mon $mport, $lport> form) to get killed. |
|
|
727 | |
|
|
728 | If a C<@reason> is specified, then linked ports (C<mon $mport, $lport> |
|
|
729 | form) get killed with the same reason. |
|
|
730 | |
|
|
731 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
|
|
732 | will be reported as reason C<< die => $@ >>. |
|
|
733 | |
|
|
734 | Transport/communication errors are reported as C<< transport_error => |
|
|
735 | $message >>. |
|
|
736 | |
|
|
737 | =cut |
|
|
738 | |
|
|
739 | =item $port = spawn $node, $initfunc[, @initdata] |
|
|
740 | |
|
|
741 | Creates a port on the node C<$node> (which can also be a port ID, in which |
|
|
742 | case it's the node where that port resides). |
|
|
743 | |
|
|
744 | The port ID of the newly created port is returned immediately, and it is |
|
|
745 | possible to immediately start sending messages or to monitor the port. |
|
|
746 | |
|
|
747 | After the port has been created, the init function is called on the remote |
|
|
748 | node, in the same context as a C<rcv> callback. This function must be a |
|
|
749 | fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To |
|
|
750 | specify a function in the main program, use C<::name>. |
|
|
751 | |
|
|
752 | If the function doesn't exist, then the node tries to C<require> |
|
|
753 | the package, then the package above the package and so on (e.g. |
|
|
754 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
|
|
755 | exists or it runs out of package names. |
|
|
756 | |
|
|
757 | The init function is then called with the newly-created port as context |
|
|
758 | object (C<$SELF>) and the C<@initdata> values as arguments. It I<must> |
|
|
759 | call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise |
|
|
760 | the port might not get created. |
|
|
761 | |
|
|
762 | A common idiom is to pass a local port, immediately monitor the spawned |
|
|
763 | port, and in the remote init function, immediately monitor the passed |
|
|
764 | local port. This two-way monitoring ensures that both ports get cleaned up |
|
|
765 | when there is a problem. |
|
|
766 | |
|
|
767 | C<spawn> guarantees that the C<$initfunc> has no visible effects on the |
|
|
768 | caller before C<spawn> returns (by delaying invocation when spawn is |
|
|
769 | called for the local node). |
|
|
770 | |
|
|
771 | Example: spawn a chat server port on C<$othernode>. |
|
|
772 | |
|
|
773 | # this node, executed from within a port context: |
|
|
774 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
|
|
775 | mon $server; |
|
|
776 | |
|
|
777 | # init function on C<$othernode> |
|
|
778 | sub connect { |
|
|
779 | my ($srcport) = @_; |
|
|
780 | |
|
|
781 | mon $srcport; |
|
|
782 | |
|
|
783 | rcv $SELF, sub { |
|
|
784 | ... |
|
|
785 | }; |
|
|
786 | } |
|
|
787 | |
|
|
788 | =cut |
|
|
789 | |
|
|
790 | sub _spawn { |
|
|
791 | my $port = shift; |
|
|
792 | my $init = shift; |
|
|
793 | |
|
|
794 | # rcv will create the actual port |
|
|
795 | local $SELF = "$NODE#$port"; |
|
|
796 | eval { |
|
|
797 | &{ load_func $init } |
|
|
798 | }; |
|
|
799 | _self_die if $@; |
|
|
800 | } |
|
|
801 | |
|
|
802 | sub spawn(@) { |
|
|
803 | my ($nodeid, undef) = split /#/, shift, 2; |
|
|
804 | |
|
|
805 | my $id = $RUNIQ . ++$ID; |
|
|
806 | |
|
|
807 | $_[0] =~ /::/ |
|
|
808 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
|
|
809 | |
|
|
810 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
|
|
811 | |
|
|
812 | "$nodeid#$id" |
|
|
813 | } |
|
|
814 | |
|
|
815 | |
|
|
816 | =item after $timeout, @msg |
|
|
817 | |
|
|
818 | =item after $timeout, $callback |
|
|
819 | |
|
|
820 | Either sends the given message, or call the given callback, after the |
|
|
821 | specified number of seconds. |
|
|
822 | |
|
|
823 | This is simply a utility function that comes in handy at times - the |
|
|
824 | AnyEvent::MP author is not convinced of the wisdom of having it, though, |
|
|
825 | so it may go away in the future. |
|
|
826 | |
|
|
827 | =cut |
|
|
828 | |
|
|
829 | sub after($@) { |
|
|
830 | my ($timeout, @action) = @_; |
|
|
831 | |
|
|
832 | my $t; $t = AE::timer $timeout, 0, sub { |
|
|
833 | undef $t; |
|
|
834 | ref $action[0] |
|
|
835 | ? $action[0]() |
|
|
836 | : snd @action; |
|
|
837 | }; |
|
|
838 | } |
|
|
839 | |
|
|
840 | #=item $cb2 = timeout $seconds, $cb[, @args] |
|
|
841 | |
|
|
842 | =item cal $port, @msg, $callback[, $timeout] |
|
|
843 | |
|
|
844 | A simple form of RPC - sends a message to the given C<$port> with the |
|
|
845 | given contents (C<@msg>), but adds a reply port to the message. |
|
|
846 | |
|
|
847 | The reply port is created temporarily just for the purpose of receiving |
|
|
848 | the reply, and will be C<kil>ed when no longer needed. |
|
|
849 | |
|
|
850 | A reply message sent to the port is passed to the C<$callback> as-is. |
|
|
851 | |
|
|
852 | If an optional time-out (in seconds) is given and it is not C<undef>, |
|
|
853 | then the callback will be called without any arguments after the time-out |
|
|
854 | elapsed and the port is C<kil>ed. |
|
|
855 | |
|
|
856 | If no time-out is given (or it is C<undef>), then the local port will |
|
|
857 | monitor the remote port instead, so it eventually gets cleaned-up. |
|
|
858 | |
|
|
859 | Currently this function returns the temporary port, but this "feature" |
|
|
860 | might go in future versions unless you can make a convincing case that |
|
|
861 | this is indeed useful for something. |
|
|
862 | |
|
|
863 | =cut |
|
|
864 | |
|
|
865 | sub cal(@) { |
|
|
866 | my $timeout = ref $_[-1] ? undef : pop; |
|
|
867 | my $cb = pop; |
|
|
868 | |
|
|
869 | my $port = port { |
|
|
870 | undef $timeout; |
|
|
871 | kil $SELF; |
|
|
872 | &$cb; |
|
|
873 | }; |
|
|
874 | |
|
|
875 | if (defined $timeout) { |
|
|
876 | $timeout = AE::timer $timeout, 0, sub { |
|
|
877 | undef $timeout; |
|
|
878 | kil $port; |
|
|
879 | $cb->(); |
|
|
880 | }; |
|
|
881 | } else { |
|
|
882 | mon $_[0], sub { |
|
|
883 | kil $port; |
|
|
884 | $cb->(); |
|
|
885 | }; |
|
|
886 | } |
|
|
887 | |
|
|
888 | push @_, $port; |
|
|
889 | &snd; |
|
|
890 | |
|
|
891 | $port |
|
|
892 | } |
|
|
893 | |
253 | =back |
894 | =back |
254 | |
895 | |
255 | =head1 FUNCTIONS FOR NODES |
896 | =head1 DISTRIBUTED DATABASE |
|
|
897 | |
|
|
898 | AnyEvent::MP comes with a simple distributed database. The database will |
|
|
899 | be mirrored asynchronously at all global nodes. Other nodes bind to one of |
|
|
900 | the global nodes for their needs. |
|
|
901 | |
|
|
902 | The database consists of a two-level hash - a hash contains a hash which |
|
|
903 | contains values. |
|
|
904 | |
|
|
905 | The top level hash key is called "family", and the second-level hash key |
|
|
906 | is called "subkey" or simply "key". |
|
|
907 | |
|
|
908 | The family must be alphanumeric, i.e. start with a letter and consist |
|
|
909 | of letters, digits, underscores and colons (C<[A-Za-z][A-Za-z0-9_:]*>, |
|
|
910 | pretty much like Perl module names. |
|
|
911 | |
|
|
912 | As the family namespace is global, it is recommended to prefix family names |
|
|
913 | with the name of the application or module using it. |
|
|
914 | |
|
|
915 | The subkeys must be non-empty strings, with no further restrictions. |
|
|
916 | |
|
|
917 | The values should preferably be strings, but other perl scalars should |
|
|
918 | work as well (such as undef, arrays and hashes). |
|
|
919 | |
|
|
920 | Every database entry is owned by one node - adding the same family/subkey |
|
|
921 | combination on multiple nodes will not cause discomfort for AnyEvent::MP, |
|
|
922 | but the result might be nondeterministic, i.e. the key might have |
|
|
923 | different values on different nodes. |
|
|
924 | |
|
|
925 | Different subkeys in the same family can be owned by different nodes |
|
|
926 | without problems, and in fact, this is the common method to create worker |
|
|
927 | pools. For example, a worker port for image scaling might do this: |
|
|
928 | |
|
|
929 | db_set my_image_scalers => $port; |
|
|
930 | |
|
|
931 | And clients looking for an image scaler will want to get the |
|
|
932 | C<my_image_scalers> keys from time to time: |
|
|
933 | |
|
|
934 | db_keys my_image_scalers => sub { |
|
|
935 | @ports = @{ $_[0] }; |
|
|
936 | }; |
|
|
937 | |
|
|
938 | Or better yet, they want to monitor the database family, so they always |
|
|
939 | have a reasonable up-to-date copy: |
|
|
940 | |
|
|
941 | db_mon my_image_scalers => sub { |
|
|
942 | @ports = keys %{ $_[0] }; |
|
|
943 | }; |
|
|
944 | |
|
|
945 | In general, you can set or delete single subkeys, but query and monitor |
|
|
946 | whole families only. |
|
|
947 | |
|
|
948 | If you feel the need to monitor or query a single subkey, try giving it |
|
|
949 | it's own family. |
|
|
950 | |
|
|
951 | =over |
|
|
952 | |
|
|
953 | =item db_set $family => $subkey [=> $value] |
|
|
954 | |
|
|
955 | Sets (or replaces) a key to the database - if C<$value> is omitted, |
|
|
956 | C<undef> is used instead. |
|
|
957 | |
|
|
958 | =item db_del $family => $subkey... |
|
|
959 | |
|
|
960 | Deletes one or more subkeys from the database family. |
|
|
961 | |
|
|
962 | =item $guard = db_reg $family => $subkey [=> $value] |
|
|
963 | |
|
|
964 | Sets the key on the database and returns a guard. When the guard is |
|
|
965 | destroyed, the key is deleted from the database. If C<$value> is missing, |
|
|
966 | then C<undef> is used. |
|
|
967 | |
|
|
968 | =item db_family $family => $cb->(\%familyhash) |
|
|
969 | |
|
|
970 | Queries the named database C<$family> and call the callback with the |
|
|
971 | family represented as a hash. You can keep and freely modify the hash. |
|
|
972 | |
|
|
973 | =item db_keys $family => $cb->(\@keys) |
|
|
974 | |
|
|
975 | Same as C<db_family>, except it only queries the family I<subkeys> and passes |
|
|
976 | them as array reference to the callback. |
|
|
977 | |
|
|
978 | =item db_values $family => $cb->(\@values) |
|
|
979 | |
|
|
980 | Same as C<db_family>, except it only queries the family I<values> and passes them |
|
|
981 | as array reference to the callback. |
|
|
982 | |
|
|
983 | =item $guard = db_mon $family => $cb->($familyhash, \@added, \@changed, \@deleted) |
|
|
984 | |
|
|
985 | Creates a monitor on the given database family. Each time a key is set |
|
|
986 | or or is deleted the callback is called with a hash containing the |
|
|
987 | database family and three lists of added, changed and deleted subkeys, |
|
|
988 | respectively. If no keys have changed then the array reference might be |
|
|
989 | C<undef> or even missing. |
|
|
990 | |
|
|
991 | The family hash reference and the key arrays belong to AnyEvent::MP and |
|
|
992 | B<must not be modified or stored> by the callback. When in doubt, make a |
|
|
993 | copy. |
|
|
994 | |
|
|
995 | As soon as possible after the monitoring starts, the callback will be |
|
|
996 | called with the intiial contents of the family, even if it is empty, |
|
|
997 | i.e. there will always be a timely call to the callback with the current |
|
|
998 | contents. |
|
|
999 | |
|
|
1000 | It is possible that the callback is called with a change event even though |
|
|
1001 | the subkey is already present and the value has not changed. |
|
|
1002 | |
|
|
1003 | The monitoring stops when the guard object is destroyed. |
|
|
1004 | |
|
|
1005 | Example: on every change to the family "mygroup", print out all keys. |
|
|
1006 | |
|
|
1007 | my $guard = db_mon mygroup => sub { |
|
|
1008 | my ($family, $a, $c, $d) = @_; |
|
|
1009 | print "mygroup members: ", (join " ", keys %$family), "\n"; |
|
|
1010 | }; |
|
|
1011 | |
|
|
1012 | Exmaple: wait until the family "My::Module::workers" is non-empty. |
|
|
1013 | |
|
|
1014 | my $guard; $guard = db_mon My::Module::workers => sub { |
|
|
1015 | my ($family, $a, $c, $d) = @_; |
|
|
1016 | return unless %$family; |
|
|
1017 | undef $guard; |
|
|
1018 | print "My::Module::workers now nonempty\n"; |
|
|
1019 | }; |
|
|
1020 | |
|
|
1021 | Example: print all changes to the family "AnyRvent::Fantasy::Module". |
|
|
1022 | |
|
|
1023 | my $guard = db_mon AnyRvent::Fantasy::Module => sub { |
|
|
1024 | my ($family, $a, $c, $d) = @_; |
|
|
1025 | |
|
|
1026 | print "+$_=$family->{$_}\n" for @$a; |
|
|
1027 | print "*$_=$family->{$_}\n" for @$c; |
|
|
1028 | print "-$_=$family->{$_}\n" for @$d; |
|
|
1029 | }; |
|
|
1030 | |
|
|
1031 | =cut |
|
|
1032 | |
|
|
1033 | =back |
|
|
1034 | |
|
|
1035 | =head1 AnyEvent::MP vs. Distributed Erlang |
|
|
1036 | |
|
|
1037 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
|
|
1038 | == aemp node, Erlang process == aemp port), so many of the documents and |
|
|
1039 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
|
|
1040 | sample: |
|
|
1041 | |
|
|
1042 | http://www.erlang.se/doc/programming_rules.shtml |
|
|
1043 | http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
|
|
1044 | http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6 |
|
|
1045 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
|
|
1046 | |
|
|
1047 | Despite the similarities, there are also some important differences: |
256 | |
1048 | |
257 | =over 4 |
1049 | =over 4 |
258 | |
1050 | |
259 | =item mon $noderef, $callback->($noderef, $status, $) |
1051 | =item * Node IDs are arbitrary strings in AEMP. |
260 | |
1052 | |
261 | Monitors the given noderef. |
1053 | Erlang relies on special naming and DNS to work everywhere in the same |
|
|
1054 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
|
|
1055 | configuration or DNS), and possibly the addresses of some seed nodes, but |
|
|
1056 | will otherwise discover other nodes (and their IDs) itself. |
262 | |
1057 | |
263 | =item become_public endpoint... |
1058 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
|
|
1059 | uses "local ports are like remote ports". |
264 | |
1060 | |
265 | Tells the node to become a public node, i.e. reachable from other nodes. |
1061 | The failure modes for local ports are quite different (runtime errors |
|
|
1062 | only) then for remote ports - when a local port dies, you I<know> it dies, |
|
|
1063 | when a connection to another node dies, you know nothing about the other |
|
|
1064 | port. |
266 | |
1065 | |
267 | If no arguments are given, or the first argument is C<undef>, then |
1066 | Erlang pretends remote ports are as reliable as local ports, even when |
268 | AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the |
1067 | they are not. |
269 | local nodename resolves to. |
|
|
270 | |
1068 | |
271 | Otherwise the first argument must be an array-reference with transport |
1069 | AEMP encourages a "treat remote ports differently" philosophy, with local |
272 | endpoints ("ip:port", "hostname:port") or port numbers (in which case the |
1070 | ports being the special case/exception, where transport errors cannot |
273 | local nodename is used as hostname). The endpoints are all resolved and |
1071 | occur. |
274 | will become the node reference. |
|
|
275 | |
1072 | |
276 | =cut |
1073 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
|
|
1074 | |
|
|
1075 | Erlang uses processes that selectively receive messages out of order, and |
|
|
1076 | therefore needs a queue. AEMP is event based, queuing messages would serve |
|
|
1077 | no useful purpose. For the same reason the pattern-matching abilities |
|
|
1078 | of AnyEvent::MP are more limited, as there is little need to be able to |
|
|
1079 | filter messages without dequeuing them. |
|
|
1080 | |
|
|
1081 | This is not a philosophical difference, but simply stems from AnyEvent::MP |
|
|
1082 | being event-based, while Erlang is process-based. |
|
|
1083 | |
|
|
1084 | You cna have a look at L<Coro::MP> for a more Erlang-like process model on |
|
|
1085 | top of AEMP and Coro threads. |
|
|
1086 | |
|
|
1087 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
|
|
1088 | |
|
|
1089 | Sending messages in Erlang is synchronous and blocks the process until |
|
|
1090 | a conenction has been established and the message sent (and so does not |
|
|
1091 | need a queue that can overflow). AEMP sends return immediately, connection |
|
|
1092 | establishment is handled in the background. |
|
|
1093 | |
|
|
1094 | =item * Erlang suffers from silent message loss, AEMP does not. |
|
|
1095 | |
|
|
1096 | Erlang implements few guarantees on messages delivery - messages can get |
|
|
1097 | lost without any of the processes realising it (i.e. you send messages a, |
|
|
1098 | b, and c, and the other side only receives messages a and c). |
|
|
1099 | |
|
|
1100 | AEMP guarantees (modulo hardware errors) correct ordering, and the |
|
|
1101 | guarantee that after one message is lost, all following ones sent to the |
|
|
1102 | same port are lost as well, until monitoring raises an error, so there are |
|
|
1103 | no silent "holes" in the message sequence. |
|
|
1104 | |
|
|
1105 | If you want your software to be very reliable, you have to cope with |
|
|
1106 | corrupted and even out-of-order messages in both Erlang and AEMP. AEMP |
|
|
1107 | simply tries to work better in common error cases, such as when a network |
|
|
1108 | link goes down. |
|
|
1109 | |
|
|
1110 | =item * Erlang can send messages to the wrong port, AEMP does not. |
|
|
1111 | |
|
|
1112 | In Erlang it is quite likely that a node that restarts reuses an Erlang |
|
|
1113 | process ID known to other nodes for a completely different process, |
|
|
1114 | causing messages destined for that process to end up in an unrelated |
|
|
1115 | process. |
|
|
1116 | |
|
|
1117 | AEMP does not reuse port IDs, so old messages or old port IDs floating |
|
|
1118 | around in the network will not be sent to an unrelated port. |
|
|
1119 | |
|
|
1120 | =item * Erlang uses unprotected connections, AEMP uses secure |
|
|
1121 | authentication and can use TLS. |
|
|
1122 | |
|
|
1123 | AEMP can use a proven protocol - TLS - to protect connections and |
|
|
1124 | securely authenticate nodes. |
|
|
1125 | |
|
|
1126 | =item * The AEMP protocol is optimised for both text-based and binary |
|
|
1127 | communications. |
|
|
1128 | |
|
|
1129 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
|
|
1130 | language independent text-only protocols (good for debugging), and binary, |
|
|
1131 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
|
|
1132 | used, the protocol is actually completely text-based. |
|
|
1133 | |
|
|
1134 | It has also been carefully designed to be implementable in other languages |
|
|
1135 | with a minimum of work while gracefully degrading functionality to make the |
|
|
1136 | protocol simple. |
|
|
1137 | |
|
|
1138 | =item * AEMP has more flexible monitoring options than Erlang. |
|
|
1139 | |
|
|
1140 | In Erlang, you can chose to receive I<all> exit signals as messages or |
|
|
1141 | I<none>, there is no in-between, so monitoring single Erlang processes is |
|
|
1142 | difficult to implement. |
|
|
1143 | |
|
|
1144 | Monitoring in AEMP is more flexible than in Erlang, as one can choose |
|
|
1145 | between automatic kill, exit message or callback on a per-port basis. |
|
|
1146 | |
|
|
1147 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
|
|
1148 | |
|
|
1149 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
|
|
1150 | same way as linking is (except linking is unreliable in Erlang). |
|
|
1151 | |
|
|
1152 | In AEMP, you don't "look up" registered port names or send to named ports |
|
|
1153 | that might or might not be persistent. Instead, you normally spawn a port |
|
|
1154 | on the remote node. The init function monitors you, and you monitor the |
|
|
1155 | remote port. Since both monitors are local to the node, they are much more |
|
|
1156 | reliable (no need for C<spawn_link>). |
|
|
1157 | |
|
|
1158 | This also saves round-trips and avoids sending messages to the wrong port |
|
|
1159 | (hard to do in Erlang). |
277 | |
1160 | |
278 | =back |
1161 | =back |
279 | |
1162 | |
280 | =head1 NODE MESSAGES |
1163 | =head1 RATIONALE |
281 | |
|
|
282 | Nodes understand the following messages sent to them. Many of them take |
|
|
283 | arguments called C<@reply>, which will simply be used to compose a reply |
|
|
284 | message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and |
|
|
285 | the remaining arguments are simply the message data. |
|
|
286 | |
1164 | |
287 | =over 4 |
1165 | =over 4 |
288 | |
1166 | |
289 | =cut |
1167 | =item Why strings for port and node IDs, why not objects? |
290 | |
1168 | |
291 | =item wkp => $name, @reply |
1169 | We considered "objects", but found that the actual number of methods |
|
|
1170 | that can be called are quite low. Since port and node IDs travel over |
|
|
1171 | the network frequently, the serialising/deserialising would add lots of |
|
|
1172 | overhead, as well as having to keep a proxy object everywhere. |
292 | |
1173 | |
293 | Replies with the port ID of the specified well-known port, or C<undef>. |
1174 | Strings can easily be printed, easily serialised etc. and need no special |
|
|
1175 | procedures to be "valid". |
294 | |
1176 | |
295 | =item devnull => ... |
1177 | And as a result, a port with just a default receiver consists of a single |
|
|
1178 | code reference stored in a global hash - it can't become much cheaper. |
296 | |
1179 | |
297 | Generic data sink/CPU heat conversion. |
1180 | =item Why favour JSON, why not a real serialising format such as Storable? |
298 | |
1181 | |
299 | =item relay => $port, @msg |
1182 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
|
|
1183 | format, but currently there is no way to make a node use Storable by |
|
|
1184 | default (although all nodes will accept it). |
300 | |
1185 | |
301 | Simply forwards the message to the given port. |
1186 | The default framing protocol is JSON because a) JSON::XS is many times |
|
|
1187 | faster for small messages and b) most importantly, after years of |
|
|
1188 | experience we found that object serialisation is causing more problems |
|
|
1189 | than it solves: Just like function calls, objects simply do not travel |
|
|
1190 | easily over the network, mostly because they will always be a copy, so you |
|
|
1191 | always have to re-think your design. |
302 | |
1192 | |
303 | =item eval => $string[ @reply] |
1193 | Keeping your messages simple, concentrating on data structures rather than |
304 | |
1194 | objects, will keep your messages clean, tidy and efficient. |
305 | Evaluates the given string. If C<@reply> is given, then a message of the |
|
|
306 | form C<@reply, $@, @evalres> is sent. |
|
|
307 | |
|
|
308 | Example: crash another node. |
|
|
309 | |
|
|
310 | snd $othernode, eval => "exit"; |
|
|
311 | |
|
|
312 | =item time => @reply |
|
|
313 | |
|
|
314 | Replies the the current node time to C<@reply>. |
|
|
315 | |
|
|
316 | Example: tell the current node to send the current time to C<$myport> in a |
|
|
317 | C<timereply> message. |
|
|
318 | |
|
|
319 | snd $NODE, time => $myport, timereply => 1, 2; |
|
|
320 | # => snd $myport, timereply => 1, 2, <time> |
|
|
321 | |
1195 | |
322 | =back |
1196 | =back |
323 | |
1197 | |
324 | =head1 SEE ALSO |
1198 | =head1 SEE ALSO |
|
|
1199 | |
|
|
1200 | L<AnyEvent::MP::Intro> - a gentle introduction. |
|
|
1201 | |
|
|
1202 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
|
|
1203 | |
|
|
1204 | L<AnyEvent::MP::Global> - network maintenance and port groups, to find |
|
|
1205 | your applications. |
|
|
1206 | |
|
|
1207 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
|
|
1208 | |
|
|
1209 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
|
|
1210 | all nodes. |
325 | |
1211 | |
326 | L<AnyEvent>. |
1212 | L<AnyEvent>. |
327 | |
1213 | |
328 | =head1 AUTHOR |
1214 | =head1 AUTHOR |
329 | |
1215 | |