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 prot 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. |
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. |
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66 | |
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67 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
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68 | manual page and the examples under F<eg/>. |
31 | |
69 | |
32 | =head1 CONCEPTS |
70 | =head1 CONCEPTS |
33 | |
71 | |
34 | =over 4 |
72 | =over 4 |
35 | |
73 | |
36 | =item port |
74 | =item port |
37 | |
75 | |
38 | 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 |
39 | you can register C<rcv> handlers with. All C<rcv> handlers will receive |
77 | messages to (with the C<snd> function). |
40 | messages they match, messages will not be queued. |
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41 | |
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 | |
42 | =item port id - C<noderef#portname> |
83 | =item port ID - C<nodeid#portname> |
43 | |
84 | |
44 | 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 |
45 | by a port name (a printable string of unspecified format). |
86 | separator, and a port name (a printable string of unspecified format). |
46 | |
87 | |
47 | =item node |
88 | =item node |
48 | |
89 | |
49 | 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, |
50 | 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 |
51 | among other things. |
92 | ports. |
52 | |
93 | |
53 | Initially, nodes are either private (single-process only) or hidden |
94 | Nodes are either public (have one or more listening ports) or private |
54 | (connected to a master node only). Only when they epxlicitly "become |
95 | (no listening ports). Private nodes cannot talk to other private nodes |
55 | public" can you send them messages from unrelated other nodes. |
96 | currently. |
56 | |
97 | |
57 | =item noderef - C<host:port,host:port...>, C<id@noderef, C<id> |
98 | =item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*> |
58 | |
99 | |
59 | 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 |
60 | 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 |
61 | 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. |
62 | |
139 | |
63 | =back |
140 | =back |
64 | |
141 | |
65 | =head1 VARIABLES/FUNCTIONS |
142 | =head1 VARIABLES/FUNCTIONS |
66 | |
143 | |
… | |
… | |
68 | |
145 | |
69 | =cut |
146 | =cut |
70 | |
147 | |
71 | package AnyEvent::MP; |
148 | package AnyEvent::MP; |
72 | |
149 | |
73 | use AnyEvent::MP::Util (); |
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74 | use AnyEvent::MP::Node; |
150 | use AnyEvent::MP::Kernel; |
75 | use AnyEvent::MP::Transport; |
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76 | |
151 | |
77 | use utf8; |
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78 | use common::sense; |
152 | use common::sense; |
79 | |
153 | |
80 | use Carp (); |
154 | use Carp (); |
81 | |
155 | |
82 | use AE (); |
156 | use AE (); |
83 | |
157 | |
84 | use base "Exporter"; |
158 | use base "Exporter"; |
85 | |
159 | |
86 | our $VERSION = '0.0'; |
160 | our $VERSION = 1.23; |
87 | our @EXPORT = qw(NODE $NODE $PORT snd rcv _any_); |
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88 | |
161 | |
89 | our $DEFAULT_SECRET; |
162 | our @EXPORT = qw( |
90 | our $DEFAULT_PORT = "4040"; |
163 | NODE $NODE *SELF node_of after |
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164 | configure |
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165 | snd rcv mon mon_guard kil psub peval spawn cal |
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166 | port |
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167 | ); |
91 | |
168 | |
92 | our $CONNECT_INTERVAL = 5; # new connect every 5s, at least |
169 | our $SELF; |
93 | our $CONNECT_TIMEOUT = 30; # includes handshake |
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94 | |
170 | |
95 | sub default_secret { |
171 | sub _self_die() { |
96 | unless (defined $DEFAULT_SECRET) { |
172 | my $msg = $@; |
97 | if (open my $fh, "<$ENV{HOME}/.aemp-secret") { |
173 | $msg =~ s/\n+$// unless ref $msg; |
98 | sysread $fh, $DEFAULT_SECRET, -s $fh; |
174 | kil $SELF, die => $msg; |
99 | } else { |
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100 | $DEFAULT_SECRET = AnyEvent::MP::Util::nonce 32; |
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101 | } |
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102 | } |
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103 | |
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104 | $DEFAULT_SECRET |
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105 | } |
175 | } |
106 | |
176 | |
107 | =item NODE / $NODE |
177 | =item $thisnode = NODE / $NODE |
108 | |
178 | |
109 | The C<NODE ()> function and the C<$NODE> variable contain the noderef of |
179 | The C<NODE> function returns, and the C<$NODE> variable contains, the node |
110 | the local node. The value is initialised by a call to C<become_public> or |
180 | ID of the node running in the current process. This value is initialised by |
111 | C<become_slave>, after which all local port identifiers become invalid. |
181 | a call to C<configure>. |
112 | |
182 | |
113 | =cut |
183 | =item $nodeid = node_of $port |
114 | |
184 | |
115 | our $UNIQ = sprintf "%x.%x", $$, time; # per-process/node unique cookie |
185 | Extracts and returns the node ID from a port ID or a node ID. |
116 | our $PUBLIC = 0; |
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117 | our $NODE; |
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118 | our $PORT; |
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119 | |
186 | |
120 | our %NODE; # node id to transport mapping, or "undef", for local node |
187 | =item configure $profile, key => value... |
121 | our %PORT; # local ports |
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122 | our %LISTENER; # local transports |
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123 | |
188 | |
124 | sub NODE() { $NODE } |
189 | =item configure key => value... |
125 | |
190 | |
126 | { |
191 | Before a node can talk to other nodes on the network (i.e. enter |
127 | use POSIX (); |
192 | "distributed mode") it has to configure itself - the minimum a node needs |
128 | my $nodename = (POSIX::uname)[1]; |
193 | to know is its own name, and optionally it should know the addresses of |
129 | $NODE = "$$\@$nodename"; |
194 | some other nodes in the network to discover other nodes. |
130 | } |
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131 | |
195 | |
132 | sub _ANY_() { 1 } |
196 | This function configures a node - it must be called exactly once (or |
133 | sub _any_() { \&_ANY_ } |
197 | never) before calling other AnyEvent::MP functions. |
134 | |
198 | |
135 | sub add_node { |
199 | =over 4 |
136 | my ($noderef) = @_; |
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137 | |
200 | |
138 | return $NODE{$noderef} |
201 | =item step 1, gathering configuration from profiles |
139 | if exists $NODE{$noderef}; |
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140 | |
202 | |
141 | for (split /,/, $noderef) { |
203 | The function first looks up a profile in the aemp configuration (see the |
142 | return $NODE{$noderef} = $NODE{$_} |
204 | L<aemp> commandline utility). The profile name can be specified via the |
143 | if exists $NODE{$_}; |
205 | named C<profile> parameter or can simply be the first parameter). If it is |
144 | } |
206 | missing, then the nodename (F<uname -n>) will be used as profile name. |
145 | |
207 | |
146 | # for indirect sends, use a different class |
208 | The profile data is then gathered as follows: |
147 | my $node = new AnyEvent::MP::Node::Direct $noderef; |
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148 | |
209 | |
149 | $NODE{$_} = $node |
210 | First, all remaining key => value pairs (all of which are conveniently |
150 | for $noderef, split /,/, $noderef; |
211 | undocumented at the moment) will be interpreted as configuration |
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212 | data. Then they will be overwritten by any values specified in the global |
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213 | default configuration (see the F<aemp> utility), then the chain of |
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214 | profiles chosen by the profile name (and any C<parent> attributes). |
151 | |
215 | |
152 | $node |
216 | That means that the values specified in the profile have highest priority |
153 | } |
217 | and the values specified directly via C<configure> have lowest priority, |
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218 | and can only be used to specify defaults. |
154 | |
219 | |
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220 | If the profile specifies a node ID, then this will become the node ID of |
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221 | this process. If not, then the profile name will be used as node ID. The |
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222 | special node ID of C<anon/> will be replaced by a random node ID. |
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223 | |
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224 | =item step 2, bind listener sockets |
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225 | |
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226 | The next step is to look up the binds in the profile, followed by binding |
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227 | aemp protocol listeners on all binds specified (it is possible and valid |
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228 | to have no binds, meaning that the node cannot be contacted form the |
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229 | outside. This means the node cannot talk to other nodes that also have no |
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230 | binds, but it can still talk to all "normal" nodes). |
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231 | |
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232 | If the profile does not specify a binds list, then a default of C<*> is |
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233 | used, meaning the node will bind on a dynamically-assigned port on every |
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234 | local IP address it finds. |
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235 | |
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236 | =item step 3, connect to seed nodes |
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237 | |
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238 | As the last step, the seeds list from the profile is passed to the |
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239 | L<AnyEvent::MP::Global> module, which will then use it to keep |
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240 | connectivity with at least one node at any point in time. |
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241 | |
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242 | =back |
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243 | |
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244 | Example: become a distributed node using the local node name as profile. |
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245 | This should be the most common form of invocation for "daemon"-type nodes. |
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246 | |
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247 | configure |
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248 | |
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249 | Example: become an anonymous node. This form is often used for commandline |
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250 | clients. |
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251 | |
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252 | configure nodeid => "anon/"; |
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253 | |
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254 | Example: configure a node using a profile called seed, which si suitable |
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255 | for a seed node as it binds on all local addresses on a fixed port (4040, |
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256 | customary for aemp). |
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257 | |
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258 | # use the aemp commandline utility |
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259 | # aemp profile seed nodeid anon/ binds '*:4040' |
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260 | |
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261 | # then use it |
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262 | configure profile => "seed"; |
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263 | |
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264 | # or simply use aemp from the shell again: |
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265 | # aemp run profile seed |
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266 | |
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267 | # or provide a nicer-to-remember nodeid |
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268 | # aemp run profile seed nodeid "$(hostname)" |
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269 | |
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270 | =item $SELF |
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271 | |
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272 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
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273 | blocks. |
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274 | |
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275 | =item *SELF, SELF, %SELF, @SELF... |
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276 | |
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277 | Due to some quirks in how perl exports variables, it is impossible to |
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278 | just export C<$SELF>, all the symbols named C<SELF> are exported by this |
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279 | module, but only C<$SELF> is currently used. |
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280 | |
155 | =item snd $portid, type => @data |
281 | =item snd $port, type => @data |
156 | |
282 | |
157 | =item snd $portid, @msg |
283 | =item snd $port, @msg |
158 | |
284 | |
159 | Send the given message to the given port ID, which can identify either a |
285 | Send the given message to the given port, which can identify either a |
160 | local or a remote port. |
286 | local or a remote port, and must be a port ID. |
161 | |
287 | |
162 | While the message can be about anything, it is highly recommended to use |
288 | While the message can be almost anything, it is highly recommended to |
163 | a constant string as first element. |
289 | use a string as first element (a port ID, or some word that indicates a |
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290 | request type etc.) and to consist if only simple perl values (scalars, |
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291 | arrays, hashes) - if you think you need to pass an object, think again. |
164 | |
292 | |
165 | The message data effectively becomes read-only after a call to this |
293 | The message data logically becomes read-only after a call to this |
166 | function: modifying any argument is not allowed and can cause many |
294 | function: modifying any argument (or values referenced by them) is |
167 | problems. |
295 | forbidden, as there can be considerable time between the call to C<snd> |
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296 | and the time the message is actually being serialised - in fact, it might |
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297 | never be copied as within the same process it is simply handed to the |
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298 | receiving port. |
168 | |
299 | |
169 | The type of data you can transfer depends on the transport protocol: when |
300 | The type of data you can transfer depends on the transport protocol: when |
170 | JSON is used, then only strings, numbers and arrays and hashes consisting |
301 | JSON is used, then only strings, numbers and arrays and hashes consisting |
171 | of those are allowed (no objects). When Storable is used, then anything |
302 | of those are allowed (no objects). When Storable is used, then anything |
172 | that Storable can serialise and deserialise is allowed, and for the local |
303 | that Storable can serialise and deserialise is allowed, and for the local |
173 | node, anything can be passed. |
304 | node, anything can be passed. Best rely only on the common denominator of |
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305 | these. |
174 | |
306 | |
175 | =cut |
307 | =item $local_port = port |
176 | |
308 | |
177 | sub snd(@) { |
309 | Create a new local port object and returns its port ID. Initially it has |
178 | my ($noderef, $port) = split /#/, shift, 2; |
310 | no callbacks set and will throw an error when it receives messages. |
179 | |
311 | |
180 | add_node $noderef |
312 | =item $local_port = port { my @msg = @_ } |
181 | unless exists $NODE{$noderef}; |
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182 | |
313 | |
183 | $NODE{$noderef}->send (["$port", [@_]]); |
314 | Creates a new local port, and returns its ID. Semantically the same as |
184 | } |
315 | creating a port and calling C<rcv $port, $callback> on it. |
185 | |
316 | |
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317 | The block will be called for every message received on the port, with the |
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318 | global variable C<$SELF> set to the port ID. Runtime errors will cause the |
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319 | port to be C<kil>ed. The message will be passed as-is, no extra argument |
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320 | (i.e. no port ID) will be passed to the callback. |
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321 | |
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322 | If you want to stop/destroy the port, simply C<kil> it: |
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323 | |
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324 | my $port = port { |
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325 | my @msg = @_; |
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326 | ... |
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327 | kil $SELF; |
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328 | }; |
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329 | |
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330 | =cut |
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331 | |
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332 | sub rcv($@); |
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333 | |
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334 | sub _kilme { |
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335 | die "received message on port without callback"; |
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336 | } |
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337 | |
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338 | sub port(;&) { |
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339 | my $id = "$UNIQ." . $ID++; |
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340 | my $port = "$NODE#$id"; |
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341 | |
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342 | rcv $port, shift || \&_kilme; |
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343 | |
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344 | $port |
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345 | } |
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346 | |
186 | =item rcv $portid, type => $callback->(@msg) |
347 | =item rcv $local_port, $callback->(@msg) |
187 | |
348 | |
188 | =item rcv $portid, $smartmatch => $callback->(@msg) |
349 | Replaces the default callback on the specified port. There is no way to |
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350 | remove the default callback: use C<sub { }> to disable it, or better |
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351 | C<kil> the port when it is no longer needed. |
189 | |
352 | |
190 | =item rcv $portid, [$smartmatch...] => $callback->(@msg) |
353 | The global C<$SELF> (exported by this module) contains C<$port> while |
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354 | executing the callback. Runtime errors during callback execution will |
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355 | result in the port being C<kil>ed. |
191 | |
356 | |
192 | Register a callback on the port identified by C<$portid>, which I<must> be |
357 | The default callback received all messages not matched by a more specific |
193 | a local port. |
358 | C<tag> match. |
194 | |
359 | |
195 | The callback has to return a true value when its work is done, after |
360 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
196 | which is will be removed, or a false value in which case it will stay |
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197 | registered. |
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198 | |
361 | |
199 | If the match is an array reference, then it will be matched against the |
362 | Register (or replace) callbacks to be called on messages starting with the |
200 | first elements of the message, otherwise only the first element is being |
363 | given tag on the given port (and return the port), or unregister it (when |
201 | matched. |
364 | C<$callback> is C<$undef> or missing). There can only be one callback |
|
|
365 | registered for each tag. |
202 | |
366 | |
203 | Any element in the match that is specified as C<_any_> (a function |
367 | The original message will be passed to the callback, after the first |
204 | exported by this module) matches any single element of the message. |
368 | element (the tag) has been removed. The callback will use the same |
|
|
369 | environment as the default callback (see above). |
205 | |
370 | |
206 | While not required, it is highly recommended that the first matching |
371 | Example: create a port and bind receivers on it in one go. |
207 | element is a string identifying the message. The one-string-only match is |
372 | |
208 | also the most efficient match (by far). |
373 | my $port = rcv port, |
|
|
374 | msg1 => sub { ... }, |
|
|
375 | msg2 => sub { ... }, |
|
|
376 | ; |
|
|
377 | |
|
|
378 | Example: create a port, bind receivers and send it in a message elsewhere |
|
|
379 | in one go: |
|
|
380 | |
|
|
381 | snd $otherport, reply => |
|
|
382 | rcv port, |
|
|
383 | msg1 => sub { ... }, |
|
|
384 | ... |
|
|
385 | ; |
|
|
386 | |
|
|
387 | Example: temporarily register a rcv callback for a tag matching some port |
|
|
388 | (e.g. for an rpc reply) and unregister it after a message was received. |
|
|
389 | |
|
|
390 | rcv $port, $otherport => sub { |
|
|
391 | my @reply = @_; |
|
|
392 | |
|
|
393 | rcv $SELF, $otherport; |
|
|
394 | }; |
209 | |
395 | |
210 | =cut |
396 | =cut |
211 | |
397 | |
212 | sub rcv($@) { |
398 | sub rcv($@) { |
213 | my ($port, $match, $cb) = @_; |
399 | my $port = shift; |
214 | |
|
|
215 | my $port = $PORT{$port} |
|
|
216 | or do { |
|
|
217 | my ($noderef, $lport) = split /#/, $port; |
400 | my ($nodeid, $portid) = split /#/, $port, 2; |
218 | "AnyEvent::MP::Node::Self" eq ref $NODE{$noderef} |
401 | |
|
|
402 | $NODE{$nodeid} == $NODE{""} |
219 | or Carp::croak "$port: can only rcv on local ports"; |
403 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
220 | |
404 | |
221 | $PORT{$lport} |
405 | while (@_) { |
222 | or Carp::croak "$port: port does not exist"; |
406 | if (ref $_[0]) { |
223 | |
407 | if (my $self = $PORT_DATA{$portid}) { |
224 | $PORT{$port} = $PORT{$lport} # also return |
408 | "AnyEvent::MP::Port" eq ref $self |
225 | }; |
409 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
226 | |
410 | |
227 | if (!ref $match) { |
411 | $self->[0] = shift; |
228 | push @{ $port->{rc0}{$match} }, [$cb]; |
|
|
229 | } elsif (("ARRAY" eq ref $match && !ref $match->[0])) { |
|
|
230 | my ($type, @match) = @$match; |
|
|
231 | @match |
|
|
232 | ? push @{ $port->{rcv}{$match->[0]} }, [$cb, \@match] |
|
|
233 | : push @{ $port->{rc0}{$match->[0]} }, [$cb]; |
|
|
234 | } else { |
412 | } else { |
235 | push @{ $port->{any} }, [$cb, $match]; |
413 | my $cb = shift; |
236 | } |
414 | $PORT{$portid} = sub { |
237 | } |
415 | local $SELF = $port; |
238 | |
416 | eval { &$cb }; _self_die if $@; |
239 | sub _inject { |
|
|
240 | my ($port, $msg) = @{+shift}; |
|
|
241 | |
|
|
242 | $port = $PORT{$port} |
|
|
243 | or return; |
|
|
244 | |
|
|
245 | @_ = @$msg; |
|
|
246 | |
|
|
247 | for (@{ $port->{rc0}{$msg->[0]} }) { |
|
|
248 | $_ && &{$_->[0]} |
|
|
249 | && undef $_; |
|
|
250 | } |
|
|
251 | |
|
|
252 | for (@{ $port->{rcv}{$msg->[0]} }) { |
|
|
253 | $_ && [@_[1..$#{$_->[1]}]] ~~ $_->[1] |
|
|
254 | && &{$_->[0]} |
|
|
255 | && undef $_; |
|
|
256 | } |
|
|
257 | |
|
|
258 | for (@{ $port->{any} }) { |
|
|
259 | $_ && [@_[0..$#{$_->[1]}]] ~~ $_->[1] |
|
|
260 | && &{$_->[0]} |
|
|
261 | && undef $_; |
|
|
262 | } |
|
|
263 | } |
|
|
264 | |
|
|
265 | sub normalise_noderef($) { |
|
|
266 | my ($noderef) = @_; |
|
|
267 | |
|
|
268 | my $cv = AE::cv; |
|
|
269 | my @res; |
|
|
270 | |
|
|
271 | $cv->begin (sub { |
|
|
272 | my %seen; |
|
|
273 | my @refs; |
|
|
274 | for (sort { $a->[0] <=> $b->[0] } @res) { |
|
|
275 | push @refs, $_->[1] unless $seen{$_->[1]}++ |
|
|
276 | } |
|
|
277 | shift->send (join ",", @refs); |
|
|
278 | }); |
|
|
279 | |
|
|
280 | $noderef = $DEFAULT_PORT unless length $noderef; |
|
|
281 | |
|
|
282 | my $idx; |
|
|
283 | for my $t (split /,/, $noderef) { |
|
|
284 | my $pri = ++$idx; |
|
|
285 | |
|
|
286 | #TODO: this should be outside normalise_noderef and in become_public |
|
|
287 | if ($t =~ /^\d*$/) { |
|
|
288 | my $nodename = (POSIX::uname)[1]; |
|
|
289 | |
|
|
290 | $cv->begin; |
|
|
291 | AnyEvent::Socket::resolve_sockaddr $nodename, $t || "aemp=$DEFAULT_PORT", "tcp", 0, undef, sub { |
|
|
292 | for (@_) { |
|
|
293 | my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3]; |
|
|
294 | push @res, [ |
|
|
295 | $pri += 1e-5, |
|
|
296 | AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service |
|
|
297 | ]; |
|
|
298 | } |
417 | }; |
299 | $cv->end; |
418 | } |
|
|
419 | } elsif (defined $_[0]) { |
|
|
420 | my $self = $PORT_DATA{$portid} ||= do { |
|
|
421 | my $self = bless [$PORT{$portid} || sub { }, { }, $port], "AnyEvent::MP::Port"; |
|
|
422 | |
|
|
423 | $PORT{$portid} = sub { |
|
|
424 | local $SELF = $port; |
|
|
425 | |
|
|
426 | if (my $cb = $self->[1]{$_[0]}) { |
|
|
427 | shift; |
|
|
428 | eval { &$cb }; _self_die if $@; |
|
|
429 | } else { |
|
|
430 | &{ $self->[0] }; |
|
|
431 | } |
|
|
432 | }; |
|
|
433 | |
|
|
434 | $self |
300 | }; |
435 | }; |
301 | |
436 | |
302 | # my (undef, undef, undef, undef, @ipv4) = gethostbyname $nodename; |
437 | "AnyEvent::MP::Port" eq ref $self |
303 | # |
438 | or Carp::croak "$port: rcv can only be called on message matching ports, caught"; |
304 | # for (@ipv4) { |
439 | |
305 | # push @res, [ |
440 | my ($tag, $cb) = splice @_, 0, 2; |
306 | # $pri, |
441 | |
307 | # AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $_, $t || $DEFAULT_PORT, |
442 | if (defined $cb) { |
308 | # ]; |
443 | $self->[1]{$tag} = $cb; |
309 | # } |
|
|
310 | } else { |
444 | } else { |
311 | my ($host, $port) = AnyEvent::Socket::parse_hostport $t, "aemp=$DEFAULT_PORT" |
445 | delete $self->[1]{$tag}; |
312 | or Carp::croak "$t: unparsable transport descriptor"; |
|
|
313 | |
|
|
314 | $cv->begin; |
|
|
315 | AnyEvent::Socket::resolve_sockaddr $host, $port, "tcp", 0, undef, sub { |
|
|
316 | for (@_) { |
|
|
317 | my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3]; |
|
|
318 | push @res, [ |
|
|
319 | $pri += 1e-5, |
|
|
320 | AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service |
|
|
321 | ]; |
|
|
322 | } |
|
|
323 | $cv->end; |
|
|
324 | } |
446 | } |
325 | } |
447 | } |
326 | } |
448 | } |
327 | |
449 | |
328 | $cv->end; |
450 | $port |
329 | |
|
|
330 | $cv |
|
|
331 | } |
451 | } |
332 | |
452 | |
333 | sub become_public { |
453 | =item peval $port, $coderef[, @args] |
334 | return if $PUBLIC; |
|
|
335 | |
454 | |
336 | my $noderef = join ",", ref $_[0] ? @{+shift} : shift; |
455 | Evaluates the given C<$codref> within the contetx of C<$port>, that is, |
337 | my @args = @_; |
456 | when the code throews an exception the C<$port> will be killed. |
338 | |
457 | |
339 | $NODE = (normalise_noderef $noderef)->recv; |
458 | Any remaining args will be passed to the callback. Any return values will |
|
|
459 | be returned to the caller. |
340 | |
460 | |
341 | for my $t (split /,/, $NODE) { |
461 | This is useful when you temporarily want to execute code in the context of |
342 | $NODE{$t} = $NODE{""}; |
462 | a port. |
343 | |
463 | |
344 | my ($host, $port) = AnyEvent::Socket::parse_hostport $t; |
464 | Example: create a port and run some initialisation code in it's context. |
345 | |
465 | |
346 | $LISTENER{$t} = AnyEvent::MP::Transport::mp_server $host, $port, |
466 | my $port = port { ... }; |
347 | @args, |
|
|
348 | on_error => sub { |
|
|
349 | die "on_error<@_>\n";#d# |
|
|
350 | }, |
|
|
351 | on_connect => sub { |
|
|
352 | my ($tp) = @_; |
|
|
353 | |
467 | |
354 | $NODE{$tp->{remote_id}} = $_[0]; |
468 | peval $port, sub { |
355 | }, |
469 | init |
356 | sub { |
470 | or die "unable to init"; |
357 | my ($tp) = @_; |
471 | }; |
358 | |
472 | |
359 | $NODE{"$tp->{peerhost}:$tp->{peerport}"} = $tp; |
473 | =cut |
360 | }, |
474 | |
361 | ; |
475 | sub peval($$) { |
|
|
476 | local $SELF = shift; |
|
|
477 | my $cb = shift; |
|
|
478 | |
|
|
479 | if (wantarray) { |
|
|
480 | my @res = eval { &$cb }; |
|
|
481 | _self_die if $@; |
|
|
482 | @res |
|
|
483 | } else { |
|
|
484 | my $res = eval { &$cb }; |
|
|
485 | _self_die if $@; |
|
|
486 | $res |
362 | } |
487 | } |
|
|
488 | } |
363 | |
489 | |
364 | $PUBLIC = 1; |
490 | =item $closure = psub { BLOCK } |
|
|
491 | |
|
|
492 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
|
|
493 | closure is executed, sets up the environment in the same way as in C<rcv> |
|
|
494 | callbacks, i.e. runtime errors will cause the port to get C<kil>ed. |
|
|
495 | |
|
|
496 | The effect is basically as if it returned C<< sub { peval $SELF, sub { |
|
|
497 | BLOCK } } >>. |
|
|
498 | |
|
|
499 | This is useful when you register callbacks from C<rcv> callbacks: |
|
|
500 | |
|
|
501 | rcv delayed_reply => sub { |
|
|
502 | my ($delay, @reply) = @_; |
|
|
503 | my $timer = AE::timer $delay, 0, psub { |
|
|
504 | snd @reply, $SELF; |
|
|
505 | }; |
|
|
506 | }; |
|
|
507 | |
|
|
508 | =cut |
|
|
509 | |
|
|
510 | sub psub(&) { |
|
|
511 | my $cb = shift; |
|
|
512 | |
|
|
513 | my $port = $SELF |
|
|
514 | or Carp::croak "psub can only be called from within rcv or psub callbacks, not"; |
|
|
515 | |
|
|
516 | sub { |
|
|
517 | local $SELF = $port; |
|
|
518 | |
|
|
519 | if (wantarray) { |
|
|
520 | my @res = eval { &$cb }; |
|
|
521 | _self_die if $@; |
|
|
522 | @res |
|
|
523 | } else { |
|
|
524 | my $res = eval { &$cb }; |
|
|
525 | _self_die if $@; |
|
|
526 | $res |
|
|
527 | } |
|
|
528 | } |
|
|
529 | } |
|
|
530 | |
|
|
531 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
|
|
532 | |
|
|
533 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
|
|
534 | |
|
|
535 | =item $guard = mon $port # kill $SELF when $port dies |
|
|
536 | |
|
|
537 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
|
|
538 | |
|
|
539 | Monitor the given port and do something when the port is killed or |
|
|
540 | messages to it were lost, and optionally return a guard that can be used |
|
|
541 | to stop monitoring again. |
|
|
542 | |
|
|
543 | In the first form (callback), the callback is simply called with any |
|
|
544 | number of C<@reason> elements (no @reason means that the port was deleted |
|
|
545 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
|
|
546 | C<eval> if unsure. |
|
|
547 | |
|
|
548 | In the second form (another port given), the other port (C<$rcvport>) |
|
|
549 | will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on |
|
|
550 | "normal" kils nothing happens, while under all other conditions, the other |
|
|
551 | port is killed with the same reason. |
|
|
552 | |
|
|
553 | The third form (kill self) is the same as the second form, except that |
|
|
554 | C<$rvport> defaults to C<$SELF>. |
|
|
555 | |
|
|
556 | In the last form (message), a message of the form C<@msg, @reason> will be |
|
|
557 | C<snd>. |
|
|
558 | |
|
|
559 | Monitoring-actions are one-shot: once messages are lost (and a monitoring |
|
|
560 | alert was raised), they are removed and will not trigger again. |
|
|
561 | |
|
|
562 | As a rule of thumb, monitoring requests should always monitor a port from |
|
|
563 | a local port (or callback). The reason is that kill messages might get |
|
|
564 | lost, just like any other message. Another less obvious reason is that |
|
|
565 | even monitoring requests can get lost (for example, when the connection |
|
|
566 | to the other node goes down permanently). When monitoring a port locally |
|
|
567 | these problems do not exist. |
|
|
568 | |
|
|
569 | C<mon> effectively guarantees that, in the absence of hardware failures, |
|
|
570 | after starting the monitor, either all messages sent to the port will |
|
|
571 | arrive, or the monitoring action will be invoked after possible message |
|
|
572 | loss has been detected. No messages will be lost "in between" (after |
|
|
573 | the first lost message no further messages will be received by the |
|
|
574 | port). After the monitoring action was invoked, further messages might get |
|
|
575 | delivered again. |
|
|
576 | |
|
|
577 | Inter-host-connection timeouts and monitoring depend on the transport |
|
|
578 | used. The only transport currently implemented is TCP, and AnyEvent::MP |
|
|
579 | relies on TCP to detect node-downs (this can take 10-15 minutes on a |
|
|
580 | non-idle connection, and usually around two hours for idle connections). |
|
|
581 | |
|
|
582 | This means that monitoring is good for program errors and cleaning up |
|
|
583 | stuff eventually, but they are no replacement for a timeout when you need |
|
|
584 | to ensure some maximum latency. |
|
|
585 | |
|
|
586 | Example: call a given callback when C<$port> is killed. |
|
|
587 | |
|
|
588 | mon $port, sub { warn "port died because of <@_>\n" }; |
|
|
589 | |
|
|
590 | Example: kill ourselves when C<$port> is killed abnormally. |
|
|
591 | |
|
|
592 | mon $port; |
|
|
593 | |
|
|
594 | Example: send us a restart message when another C<$port> is killed. |
|
|
595 | |
|
|
596 | mon $port, $self => "restart"; |
|
|
597 | |
|
|
598 | =cut |
|
|
599 | |
|
|
600 | sub mon { |
|
|
601 | my ($nodeid, $port) = split /#/, shift, 2; |
|
|
602 | |
|
|
603 | my $node = $NODE{$nodeid} || add_node $nodeid; |
|
|
604 | |
|
|
605 | my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; |
|
|
606 | |
|
|
607 | unless (ref $cb) { |
|
|
608 | if (@_) { |
|
|
609 | # send a kill info message |
|
|
610 | my (@msg) = ($cb, @_); |
|
|
611 | $cb = sub { snd @msg, @_ }; |
|
|
612 | } else { |
|
|
613 | # simply kill other port |
|
|
614 | my $port = $cb; |
|
|
615 | $cb = sub { kil $port, @_ if @_ }; |
|
|
616 | } |
|
|
617 | } |
|
|
618 | |
|
|
619 | $node->monitor ($port, $cb); |
|
|
620 | |
|
|
621 | defined wantarray |
|
|
622 | and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }) |
|
|
623 | } |
|
|
624 | |
|
|
625 | =item $guard = mon_guard $port, $ref, $ref... |
|
|
626 | |
|
|
627 | Monitors the given C<$port> and keeps the passed references. When the port |
|
|
628 | is killed, the references will be freed. |
|
|
629 | |
|
|
630 | Optionally returns a guard that will stop the monitoring. |
|
|
631 | |
|
|
632 | This function is useful when you create e.g. timers or other watchers and |
|
|
633 | want to free them when the port gets killed (note the use of C<psub>): |
|
|
634 | |
|
|
635 | $port->rcv (start => sub { |
|
|
636 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub { |
|
|
637 | undef $timer if 0.9 < rand; |
|
|
638 | }); |
|
|
639 | }); |
|
|
640 | |
|
|
641 | =cut |
|
|
642 | |
|
|
643 | sub mon_guard { |
|
|
644 | my ($port, @refs) = @_; |
|
|
645 | |
|
|
646 | #TODO: mon-less form? |
|
|
647 | |
|
|
648 | mon $port, sub { 0 && @refs } |
|
|
649 | } |
|
|
650 | |
|
|
651 | =item kil $port[, @reason] |
|
|
652 | |
|
|
653 | Kill the specified port with the given C<@reason>. |
|
|
654 | |
|
|
655 | If no C<@reason> is specified, then the port is killed "normally" (ports |
|
|
656 | monitoring other ports will not necessarily die because a port dies |
|
|
657 | "normally"). |
|
|
658 | |
|
|
659 | Otherwise, linked ports get killed with the same reason (second form of |
|
|
660 | C<mon>, see above). |
|
|
661 | |
|
|
662 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
|
|
663 | will be reported as reason C<< die => $@ >>. |
|
|
664 | |
|
|
665 | Transport/communication errors are reported as C<< transport_error => |
|
|
666 | $message >>. |
|
|
667 | |
|
|
668 | =cut |
|
|
669 | |
|
|
670 | =item $port = spawn $node, $initfunc[, @initdata] |
|
|
671 | |
|
|
672 | Creates a port on the node C<$node> (which can also be a port ID, in which |
|
|
673 | case it's the node where that port resides). |
|
|
674 | |
|
|
675 | The port ID of the newly created port is returned immediately, and it is |
|
|
676 | possible to immediately start sending messages or to monitor the port. |
|
|
677 | |
|
|
678 | After the port has been created, the init function is called on the remote |
|
|
679 | node, in the same context as a C<rcv> callback. This function must be a |
|
|
680 | fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To |
|
|
681 | specify a function in the main program, use C<::name>. |
|
|
682 | |
|
|
683 | If the function doesn't exist, then the node tries to C<require> |
|
|
684 | the package, then the package above the package and so on (e.g. |
|
|
685 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
|
|
686 | exists or it runs out of package names. |
|
|
687 | |
|
|
688 | The init function is then called with the newly-created port as context |
|
|
689 | object (C<$SELF>) and the C<@initdata> values as arguments. It I<must> |
|
|
690 | call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise |
|
|
691 | the port might not get created. |
|
|
692 | |
|
|
693 | A common idiom is to pass a local port, immediately monitor the spawned |
|
|
694 | port, and in the remote init function, immediately monitor the passed |
|
|
695 | local port. This two-way monitoring ensures that both ports get cleaned up |
|
|
696 | when there is a problem. |
|
|
697 | |
|
|
698 | C<spawn> guarantees that the C<$initfunc> has no visible effects on the |
|
|
699 | caller before C<spawn> returns (by delaying invocation when spawn is |
|
|
700 | called for the local node). |
|
|
701 | |
|
|
702 | Example: spawn a chat server port on C<$othernode>. |
|
|
703 | |
|
|
704 | # this node, executed from within a port context: |
|
|
705 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
|
|
706 | mon $server; |
|
|
707 | |
|
|
708 | # init function on C<$othernode> |
|
|
709 | sub connect { |
|
|
710 | my ($srcport) = @_; |
|
|
711 | |
|
|
712 | mon $srcport; |
|
|
713 | |
|
|
714 | rcv $SELF, sub { |
|
|
715 | ... |
|
|
716 | }; |
|
|
717 | } |
|
|
718 | |
|
|
719 | =cut |
|
|
720 | |
|
|
721 | sub _spawn { |
|
|
722 | my $port = shift; |
|
|
723 | my $init = shift; |
|
|
724 | |
|
|
725 | # rcv will create the actual port |
|
|
726 | local $SELF = "$NODE#$port"; |
|
|
727 | eval { |
|
|
728 | &{ load_func $init } |
|
|
729 | }; |
|
|
730 | _self_die if $@; |
|
|
731 | } |
|
|
732 | |
|
|
733 | sub spawn(@) { |
|
|
734 | my ($nodeid, undef) = split /#/, shift, 2; |
|
|
735 | |
|
|
736 | my $id = "$RUNIQ." . $ID++; |
|
|
737 | |
|
|
738 | $_[0] =~ /::/ |
|
|
739 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
|
|
740 | |
|
|
741 | snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_; |
|
|
742 | |
|
|
743 | "$nodeid#$id" |
|
|
744 | } |
|
|
745 | |
|
|
746 | =item after $timeout, @msg |
|
|
747 | |
|
|
748 | =item after $timeout, $callback |
|
|
749 | |
|
|
750 | Either sends the given message, or call the given callback, after the |
|
|
751 | specified number of seconds. |
|
|
752 | |
|
|
753 | This is simply a utility function that comes in handy at times - the |
|
|
754 | AnyEvent::MP author is not convinced of the wisdom of having it, though, |
|
|
755 | so it may go away in the future. |
|
|
756 | |
|
|
757 | =cut |
|
|
758 | |
|
|
759 | sub after($@) { |
|
|
760 | my ($timeout, @action) = @_; |
|
|
761 | |
|
|
762 | my $t; $t = AE::timer $timeout, 0, sub { |
|
|
763 | undef $t; |
|
|
764 | ref $action[0] |
|
|
765 | ? $action[0]() |
|
|
766 | : snd @action; |
|
|
767 | }; |
|
|
768 | } |
|
|
769 | |
|
|
770 | =item cal $port, @msg, $callback[, $timeout] |
|
|
771 | |
|
|
772 | A simple form of RPC - sends a message to the given C<$port> with the |
|
|
773 | given contents (C<@msg>), but adds a reply port to the message. |
|
|
774 | |
|
|
775 | The reply port is created temporarily just for the purpose of receiving |
|
|
776 | the reply, and will be C<kil>ed when no longer needed. |
|
|
777 | |
|
|
778 | A reply message sent to the port is passed to the C<$callback> as-is. |
|
|
779 | |
|
|
780 | If an optional time-out (in seconds) is given and it is not C<undef>, |
|
|
781 | then the callback will be called without any arguments after the time-out |
|
|
782 | elapsed and the port is C<kil>ed. |
|
|
783 | |
|
|
784 | If no time-out is given (or it is C<undef>), then the local port will |
|
|
785 | monitor the remote port instead, so it eventually gets cleaned-up. |
|
|
786 | |
|
|
787 | Currently this function returns the temporary port, but this "feature" |
|
|
788 | might go in future versions unless you can make a convincing case that |
|
|
789 | this is indeed useful for something. |
|
|
790 | |
|
|
791 | =cut |
|
|
792 | |
|
|
793 | sub cal(@) { |
|
|
794 | my $timeout = ref $_[-1] ? undef : pop; |
|
|
795 | my $cb = pop; |
|
|
796 | |
|
|
797 | my $port = port { |
|
|
798 | undef $timeout; |
|
|
799 | kil $SELF; |
|
|
800 | &$cb; |
|
|
801 | }; |
|
|
802 | |
|
|
803 | if (defined $timeout) { |
|
|
804 | $timeout = AE::timer $timeout, 0, sub { |
|
|
805 | undef $timeout; |
|
|
806 | kil $port; |
|
|
807 | $cb->(); |
|
|
808 | }; |
|
|
809 | } else { |
|
|
810 | mon $_[0], sub { |
|
|
811 | kil $port; |
|
|
812 | $cb->(); |
|
|
813 | }; |
|
|
814 | } |
|
|
815 | |
|
|
816 | push @_, $port; |
|
|
817 | &snd; |
|
|
818 | |
|
|
819 | $port |
365 | } |
820 | } |
366 | |
821 | |
367 | =back |
822 | =back |
368 | |
823 | |
369 | =head1 NODE MESSAGES |
824 | =head1 AnyEvent::MP vs. Distributed Erlang |
370 | |
825 | |
371 | Nodes understand the following messages sent to them: |
826 | AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node |
|
|
827 | == aemp node, Erlang process == aemp port), so many of the documents and |
|
|
828 | programming techniques employed by Erlang apply to AnyEvent::MP. Here is a |
|
|
829 | sample: |
|
|
830 | |
|
|
831 | http://www.erlang.se/doc/programming_rules.shtml |
|
|
832 | http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
|
|
833 | http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6 |
|
|
834 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
|
|
835 | |
|
|
836 | Despite the similarities, there are also some important differences: |
372 | |
837 | |
373 | =over 4 |
838 | =over 4 |
374 | |
839 | |
375 | =cut |
840 | =item * Node IDs are arbitrary strings in AEMP. |
376 | |
841 | |
377 | ############################################################################# |
842 | Erlang relies on special naming and DNS to work everywhere in the same |
378 | # self node code |
843 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
|
|
844 | configuration or DNS), and possibly the addresses of some seed nodes, but |
|
|
845 | will otherwise discover other nodes (and their IDs) itself. |
379 | |
846 | |
380 | sub _new_port($) { |
847 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
381 | my ($name) = @_; |
848 | uses "local ports are like remote ports". |
382 | |
849 | |
383 | my ($noderef, $portname) = split /#/, $name; |
850 | The failure modes for local ports are quite different (runtime errors |
|
|
851 | only) then for remote ports - when a local port dies, you I<know> it dies, |
|
|
852 | when a connection to another node dies, you know nothing about the other |
|
|
853 | port. |
384 | |
854 | |
385 | $PORT{$name} = |
855 | Erlang pretends remote ports are as reliable as local ports, even when |
386 | $PORT{$portname} = { |
856 | they are not. |
387 | names => [$name, $portname], |
|
|
388 | }; |
|
|
389 | } |
|
|
390 | |
857 | |
391 | $NODE{""} = new AnyEvent::MP::Node::Self noderef => $NODE; |
858 | AEMP encourages a "treat remote ports differently" philosophy, with local |
392 | _new_port ""; |
859 | ports being the special case/exception, where transport errors cannot |
|
|
860 | occur. |
393 | |
861 | |
394 | =item relay => $port, @msg |
862 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
395 | |
863 | |
396 | Simply forwards the message to the given port. |
864 | Erlang uses processes that selectively receive messages, and therefore |
|
|
865 | needs a queue. AEMP is event based, queuing messages would serve no |
|
|
866 | useful purpose. For the same reason the pattern-matching abilities of |
|
|
867 | AnyEvent::MP are more limited, as there is little need to be able to |
|
|
868 | filter messages without dequeuing them. |
397 | |
869 | |
398 | =cut |
870 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
399 | |
871 | |
400 | rcv "", relay => \&snd; |
872 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
401 | |
873 | |
402 | =item eval => $string[ @reply] |
874 | Sending messages in Erlang is synchronous and blocks the process (and |
|
|
875 | so does not need a queue that can overflow). AEMP sends are immediate, |
|
|
876 | connection establishment is handled in the background. |
403 | |
877 | |
404 | Evaluates the given string. If C<@reply> is given, then a message of the |
878 | =item * Erlang suffers from silent message loss, AEMP does not. |
405 | form C<@reply, $@, @evalres> is sent (C<$reply[0]> is the port to reply to). |
|
|
406 | |
879 | |
407 | =cut |
880 | Erlang implements few guarantees on messages delivery - messages can get |
|
|
881 | lost without any of the processes realising it (i.e. you send messages a, |
|
|
882 | b, and c, and the other side only receives messages a and c). |
408 | |
883 | |
409 | rcv "", eval => sub { |
884 | AEMP guarantees correct ordering, and the guarantee that after one message |
410 | my (undef, $string, @reply) = @_; |
885 | is lost, all following ones sent to the same port are lost as well, until |
411 | my @res = eval $string; |
886 | monitoring raises an error, so there are no silent "holes" in the message |
412 | snd @reply, "$@", @res if @reply; |
887 | sequence. |
413 | }; |
|
|
414 | |
888 | |
415 | =item time => @reply |
889 | =item * Erlang can send messages to the wrong port, AEMP does not. |
416 | |
890 | |
417 | Replies the the current node time to C<@reply>. |
891 | In Erlang it is quite likely that a node that restarts reuses a process ID |
|
|
892 | known to other nodes for a completely different process, causing messages |
|
|
893 | destined for that process to end up in an unrelated process. |
418 | |
894 | |
419 | =cut |
895 | AEMP never reuses port IDs, so old messages or old port IDs floating |
|
|
896 | around in the network will not be sent to an unrelated port. |
420 | |
897 | |
421 | rcv "", time => sub { shift; snd @_, AE::time }; |
898 | =item * Erlang uses unprotected connections, AEMP uses secure |
|
|
899 | authentication and can use TLS. |
|
|
900 | |
|
|
901 | AEMP can use a proven protocol - TLS - to protect connections and |
|
|
902 | securely authenticate nodes. |
|
|
903 | |
|
|
904 | =item * The AEMP protocol is optimised for both text-based and binary |
|
|
905 | communications. |
|
|
906 | |
|
|
907 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
|
|
908 | language independent text-only protocols (good for debugging) and binary, |
|
|
909 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
|
|
910 | used, the protocol is actually completely text-based. |
|
|
911 | |
|
|
912 | It has also been carefully designed to be implementable in other languages |
|
|
913 | with a minimum of work while gracefully degrading functionality to make the |
|
|
914 | protocol simple. |
|
|
915 | |
|
|
916 | =item * AEMP has more flexible monitoring options than Erlang. |
|
|
917 | |
|
|
918 | In Erlang, you can chose to receive I<all> exit signals as messages |
|
|
919 | or I<none>, there is no in-between, so monitoring single processes is |
|
|
920 | difficult to implement. Monitoring in AEMP is more flexible than in |
|
|
921 | Erlang, as one can choose between automatic kill, exit message or callback |
|
|
922 | on a per-process basis. |
|
|
923 | |
|
|
924 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
|
|
925 | |
|
|
926 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
|
|
927 | same way as linking is (except linking is unreliable in Erlang). |
|
|
928 | |
|
|
929 | In AEMP, you don't "look up" registered port names or send to named ports |
|
|
930 | that might or might not be persistent. Instead, you normally spawn a port |
|
|
931 | on the remote node. The init function monitors you, and you monitor the |
|
|
932 | remote port. Since both monitors are local to the node, they are much more |
|
|
933 | reliable (no need for C<spawn_link>). |
|
|
934 | |
|
|
935 | This also saves round-trips and avoids sending messages to the wrong port |
|
|
936 | (hard to do in Erlang). |
422 | |
937 | |
423 | =back |
938 | =back |
424 | |
939 | |
|
|
940 | =head1 RATIONALE |
|
|
941 | |
|
|
942 | =over 4 |
|
|
943 | |
|
|
944 | =item Why strings for port and node IDs, why not objects? |
|
|
945 | |
|
|
946 | We considered "objects", but found that the actual number of methods |
|
|
947 | that can be called are quite low. Since port and node IDs travel over |
|
|
948 | the network frequently, the serialising/deserialising would add lots of |
|
|
949 | overhead, as well as having to keep a proxy object everywhere. |
|
|
950 | |
|
|
951 | Strings can easily be printed, easily serialised etc. and need no special |
|
|
952 | procedures to be "valid". |
|
|
953 | |
|
|
954 | And as a result, a miniport consists of a single closure stored in a |
|
|
955 | global hash - it can't become much cheaper. |
|
|
956 | |
|
|
957 | =item Why favour JSON, why not a real serialising format such as Storable? |
|
|
958 | |
|
|
959 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
|
|
960 | format, but currently there is no way to make a node use Storable by |
|
|
961 | default (although all nodes will accept it). |
|
|
962 | |
|
|
963 | The default framing protocol is JSON because a) JSON::XS is many times |
|
|
964 | faster for small messages and b) most importantly, after years of |
|
|
965 | experience we found that object serialisation is causing more problems |
|
|
966 | than it solves: Just like function calls, objects simply do not travel |
|
|
967 | easily over the network, mostly because they will always be a copy, so you |
|
|
968 | always have to re-think your design. |
|
|
969 | |
|
|
970 | Keeping your messages simple, concentrating on data structures rather than |
|
|
971 | objects, will keep your messages clean, tidy and efficient. |
|
|
972 | |
|
|
973 | =back |
|
|
974 | |
425 | =head1 SEE ALSO |
975 | =head1 SEE ALSO |
|
|
976 | |
|
|
977 | L<AnyEvent::MP::Intro> - a gentle introduction. |
|
|
978 | |
|
|
979 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
|
|
980 | |
|
|
981 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
|
|
982 | your applications. |
|
|
983 | |
|
|
984 | L<AnyEvent::MP::DataConn> - establish data connections between nodes. |
|
|
985 | |
|
|
986 | L<AnyEvent::MP::LogCatcher> - simple service to display log messages from |
|
|
987 | all nodes. |
426 | |
988 | |
427 | L<AnyEvent>. |
989 | L<AnyEvent>. |
428 | |
990 | |
429 | =head1 AUTHOR |
991 | =head1 AUTHOR |
430 | |
992 | |