AnyEvent-MP/MP.pm

=head1 NAME

AnyEvent::MP - multi-processing/message-passing framework

=head1 SYNOPSIS

   use AnyEvent::MP;

   $NODE      # contains this node's noderef
   NODE       # returns this node's noderef
   NODE $port # returns the noderef of the port

   snd $port, type => data...;

   $SELF      # receiving/own port id in rcv callbacks

   rcv $port, smartmatch => $cb->($port, @msg);

   # examples:
   rcv $port2, ping => sub { snd $_[0], "pong"; 0 };
   rcv $port1, pong => sub { warn "pong received\n" };
   snd $port2, ping => $port1;

   # more, smarter, matches (_any_ is exported by this module)
   rcv $port, [child_died => $pid] => sub { ...
   rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3

=head1 DESCRIPTION

This module (-family) implements a simple message passing framework.

Despite its simplicity, you can securely message other processes running
on the same or other hosts.

For an introduction to this module family, see the L<AnyEvent::MP::Intro>
manual page.

At the moment, this module family is severly broken and underdocumented,
so do not use. This was uploaded mainly to reserve the CPAN namespace -
stay tuned! The basic API should be finished, however.

=head1 CONCEPTS

=over 4

=item port

A port is something you can send messages to (with the C<snd> function).

Some ports allow you to register C<rcv> handlers that can match specific
messages. All C<rcv> handlers will receive messages they match, messages
will not be queued.

=item port id - C<noderef#portname>

A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
separator, and a port name (a printable string of unspecified format). An
exception is the the node port, whose ID is identical to its node
reference.

=item node

A node is a single process containing at least one port - the node
port. You can send messages to node ports to find existing ports or to
create new ports, among other things.

Nodes are either private (single-process only), slaves (connected to a
master node only) or public nodes (connectable from unrelated nodes).

=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>

A node reference is a string that either simply identifies the node (for
private and slave nodes), or contains a recipe on how to reach a given
node (for public nodes).

This recipe is simply a comma-separated list of C<address:port> pairs (for
TCP/IP, other protocols might look different).

Node references come in two flavours: resolved (containing only numerical
addresses) or unresolved (where hostnames are used instead of addresses).

Before using an unresolved node reference in a message you first have to
resolve it.

=back

=head1 VARIABLES/FUNCTIONS

=over 4

=cut

package AnyEvent::MP;

use AnyEvent::MP::Base;

use common::sense;

use Carp ();

use AE ();

use base "Exporter";

our $VERSION = '0.1';
our @EXPORT = qw(
   NODE $NODE *SELF node_of _any_
   resolve_node initialise_node
   snd rcv mon kil reg psub
   port
);

our $SELF;

sub _self_die() {
   my $msg = $@;
   $msg =~ s/\n+$// unless ref $msg;
   kil $SELF, die => $msg;
}

=item $thisnode = NODE / $NODE

The C<NODE> function returns, and the C<$NODE> variable contains
the noderef of the local node. The value is initialised by a call
to C<become_public> or C<become_slave>, after which all local port
identifiers become invalid.

=item $noderef = node_of $portid

Extracts and returns the noderef from a portid or a noderef.

=item $cv = resolve_node $noderef

Takes an unresolved node reference that may contain hostnames and
abbreviated IDs, resolves all of them and returns a resolved node
reference.

In addition to C<address:port> pairs allowed in resolved noderefs, the
following forms are supported:

=over 4

=item the empty string

An empty-string component gets resolved as if the default port (4040) was
specified.

=item naked port numbers (e.g. C<1234>)

These are resolved by prepending the local nodename and a colon, to be
further resolved.

=item hostnames (e.g. C<localhost:1234>, C<localhost>)

These are resolved by using AnyEvent::DNS to resolve them, optionally
looking up SRV records for the C<aemp=4040> port, if no port was
specified.

=back

=item $SELF

Contains the current port id while executing C<rcv> callbacks or C<psub>
blocks.

=item SELF, %SELF, @SELF...

Due to some quirks in how perl exports variables, it is impossible to
just export C<$SELF>, all the symbols called C<SELF> are exported by this
module, but only C<$SELF> is currently used.

=item snd $portid, type => @data

=item snd $portid, @msg

Send the given message to the given port ID, which can identify either
a local or a remote port, and can be either a string or soemthignt hat
stringifies a sa port ID (such as a port object :).

While the message can be about anything, it is highly recommended to use a
string as first element (a portid, or some word that indicates a request
type etc.).

The message data effectively becomes read-only after a call to this
function: modifying any argument is not allowed and can cause many
problems.

The type of data you can transfer depends on the transport protocol: when
JSON is used, then only strings, numbers and arrays and hashes consisting
of those are allowed (no objects). When Storable is used, then anything
that Storable can serialise and deserialise is allowed, and for the local
node, anything can be passed.

=item $local_port = port

Create a new local port object that can be used either as a pattern
matching port ("full port") or a single-callback port ("miniport"),
depending on how C<rcv> callbacks are bound to the object.

=item $portid = port { my @msg = @_; $finished }

Creates a "mini port", that is, a very lightweight port without any
pattern matching behind it, and returns its ID.

The block will be called for every message received on the port. When the
callback returns a true value its job is considered "done" and the port
will be destroyed. Otherwise it will stay alive.

The message will be passed as-is, no extra argument (i.e. no port id) will
be passed to the callback.

If you need the local port id in the callback, this works nicely:

   my $port; $port = port {
      snd $otherport, reply => $port;
   };

=cut

sub port(;&) {
   my $id = "$UNIQ." . $ID++;
   my $port = "$NODE#$id";

   if (@_) {
      my $cb = shift;
      $PORT{$id} = sub {
         local $SELF = $port;
         eval {
            &$cb
               and kil $id;
         };
         _self_die if $@;
      };
   } else {
      my $self = bless {
         id    => "$NODE#$id",
      }, "AnyEvent::MP::Port";

      $PORT_DATA{$id} = $self;
      $PORT{$id} = sub {
         local $SELF = $port;

         eval {
            for (@{ $self->{rc0}{$_[0]} }) {
               $_ && &{$_->[0]}
                  && undef $_;
            }

            for (@{ $self->{rcv}{$_[0]} }) {
               $_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
                  && &{$_->[0]}
                  && undef $_;
            }

            for (@{ $self->{any} }) {
               $_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
                  && &{$_->[0]}
                  && undef $_;
            }
         };
         _self_die if $@;
      };
   }

   $port
}

=item reg $portid, $name

Registers the given port under the name C<$name>. If the name already
exists it is replaced.

A port can only be registered under one well known name.

A port automatically becomes unregistered when it is killed.

=cut

sub reg(@) {
   my ($portid, $name) = @_;

   $REG{$name} = $portid;
}

=item rcv $portid, $callback->(@msg)

Replaces the callback on the specified miniport (or newly created port
object, see C<port>). Full ports are configured with the following calls:

=item rcv $portid, tagstring        => $callback->(@msg), ...

=item rcv $portid, $smartmatch      => $callback->(@msg), ...

=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...

Register callbacks to be called on matching messages on the given full
port (or newly created port).

The callback has to return a true value when its work is done, after
which is will be removed, or a false value in which case it will stay
registered.

The global C<$SELF> (exported by this module) contains C<$portid> while
executing the callback.

Runtime errors wdurign callback execution will result in the port being
C<kil>ed.

If the match is an array reference, then it will be matched against the
first elements of the message, otherwise only the first element is being
matched.

Any element in the match that is specified as C<_any_> (a function
exported by this module) matches any single element of the message.

While not required, it is highly recommended that the first matching
element is a string identifying the message. The one-string-only match is
also the most efficient match (by far).

=cut

sub rcv($@) {
   my $portid = shift;
   my ($noderef, $port) = split /#/, $port, 2;

   ($NODE{$noderef} || add_node $noderef) == $NODE{""}
      or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";

   my $self = $PORT_DATA{$port}
      or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";

   "AnyEvent::MP::Port" eq ref $self
      or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";

   while (@_) {
      my ($match, $cb) = splice @_, 0, 2;

      if (!ref $match) {
         push @{ $self->{rc0}{$match}      }, [$cb];
      } elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
         my ($type, @match) = @$match;
         @match
            ? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
            : push @{ $self->{rc0}{$match->[0]} }, [$cb];
      } else {
         push @{ $self->{any}              }, [$cb, $match];
      }
   }

   $portid
}

=item $closure = psub { BLOCK }

Remembers C<$SELF> and creates a closure out of the BLOCK. When the
closure is executed, sets up the environment in the same way as in C<rcv>
callbacks, i.e. runtime errors will cause the port to get C<kil>ed.

This is useful when you register callbacks from C<rcv> callbacks:

   rcv delayed_reply => sub {
      my ($delay, @reply) = @_;
      my $timer = AE::timer $delay, 0, psub {
         snd @reply, $SELF;
      };
   };

=cut

sub psub(&) {
   my $cb = shift;

   my $port = $SELF
      or Carp::croak "psub can only be called from within rcv or psub callbacks, not";

   sub {
      local $SELF = $port;

      if (wantarray) {
         my @res = eval { &$cb };
         _self_die if $@;
         @res
      } else {
         my $res = eval { &$cb };
         _self_die if $@;
         $res
      }
   }
}

=item $guard = mon $portid, $cb->(@reason)

=item $guard = mon $portid, $otherport

=item $guard = mon $portid, $otherport, @msg

Monitor the given port and do something when the port is killed.

In the first form, the callback is simply called with any number
of C<@reason> elements (no @reason means that the port was deleted
"normally"). Note also that I<< the callback B<must> never die >>, so use
C<eval> if unsure.

In the second form, the other port will be C<kil>'ed with C<@reason>, iff
a @reason was specified, i.e. on "normal" kils nothing happens, while
under all other conditions, the other port is killed with the same reason.

In the last form, a message of the form C<@msg, @reason> will be C<snd>.

Example: call a given callback when C<$port> is killed.

   mon $port, sub { warn "port died because of <@_>\n" };

Example: kill ourselves when C<$port> is killed abnormally.

   mon $port, $self;

Example: send us a restart message another C<$port> is killed.

   mon $port, $self => "restart";

=cut

sub mon {
   my ($noderef, $port) = split /#/, shift, 2;

   my $node = $NODE{$noderef} || add_node $noderef;

   my $cb = shift;

   unless (ref $cb) {
      if (@_) {
         # send a kill info message
         my (@msg) = ($cb, @_);
         $cb = sub { snd @msg, @_ };
      } else {
         # simply kill other port
         my $port = $cb;
         $cb = sub { kil $port, @_ if @_ };
      }
   }

   $node->monitor ($port, $cb);

   defined wantarray
      and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
}

=item $guard = mon_guard $port, $ref, $ref...

Monitors the given C<$port> and keeps the passed references. When the port
is killed, the references will be freed.

Optionally returns a guard that will stop the monitoring.

This function is useful when you create e.g. timers or other watchers and
want to free them when the port gets killed:

  $port->rcv (start => sub {
     my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
        undef $timer if 0.9 < rand;
     });
  });

=cut

sub mon_guard {
   my ($port, @refs) = @_;

   mon $port, sub { 0 && @refs }
}

=item lnk $port1, $port2

Link two ports. This is simply a shorthand for:

   mon $port1, $port2;
   mon $port2, $port1;

It means that if either one is killed abnormally, the other one gets
killed as well.

=item kil $portid[, @reason]

Kill the specified port with the given C<@reason>.

If no C<@reason> is specified, then the port is killed "normally" (linked
ports will not be kileld, or even notified).

Otherwise, linked ports get killed with the same reason (second form of
C<mon>, see below).

Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
will be reported as reason C<< die => $@ >>.

Transport/communication errors are reported as C<< transport_error =>
$message >>.

=back

=head1 FUNCTIONS FOR NODES

=over 4

=item become_public $noderef

Tells the node to become a public node, i.e. reachable from other nodes.

The first argument is the (unresolved) node reference of the local node
(if missing then the empty string is used).

It is quite common to not specify anything, in which case the local node
tries to listen on the default port, or to only specify a port number, in
which case AnyEvent::MP tries to guess the local addresses.

=cut

=back

=head1 NODE MESSAGES

Nodes understand the following messages sent to them. Many of them take
arguments called C<@reply>, which will simply be used to compose a reply
message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
the remaining arguments are simply the message data.

While other messages exist, they are not public and subject to change.

=over 4

=cut

=item lookup => $name, @reply

Replies with the port ID of the specified well-known port, or C<undef>.

=item devnull => ...

Generic data sink/CPU heat conversion.

=item relay => $port, @msg

Simply forwards the message to the given port.

=item eval => $string[ @reply]

Evaluates the given string. If C<@reply> is given, then a message of the
form C<@reply, $@, @evalres> is sent.

Example: crash another node.

   snd $othernode, eval => "exit";

=item time => @reply

Replies the the current node time to C<@reply>.

Example: tell the current node to send the current time to C<$myport> in a
C<timereply> message.

   snd $NODE, time => $myport, timereply => 1, 2;
   # => snd $myport, timereply => 1, 2, <time>

=back

=head1 AnyEvent::MP vs. Distributed Erlang

AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
== aemp node, erlang process == aemp port), so many of the documents and
programming techniques employed by erlang apply to AnyEvent::MP. Here is a
sample:

   http://www.erlang.se/doc/programming_rules.shtml
   http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
   http://erlang.org/download/erlang-book-part1.pdf      # chapters 5 and 6
   http://erlang.org/download/armstrong_thesis_2003.pdf  # chapters 4 and 5

Despite the similarities, there are also some important differences:

=over 4

=item * Node references contain the recipe on how to contact them.

Erlang relies on special naming and DNS to work everywhere in the
same way. AEMP relies on each node knowing it's own address(es), with
convenience functionality.

This means that AEMP requires a less tightly controlled environment at the
cost of longer node references and a slightly higher management overhead.

=item * Erlang uses processes and a mailbox, AEMP does not queue.

Erlang uses processes that selctively receive messages, and therefore
needs a queue. AEMP is event based, queuing messages would serve no useful
purpose.

(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).

=item * Erlang sends are synchronous, AEMP sends are asynchronous.

Sending messages in erlang is synchronous and blocks the process. AEMP
sends are immediate, connection establishment is handled in the
background.

=item * Erlang can silently lose messages, AEMP cannot.

Erlang makes few guarantees on messages delivery - messages can get lost
without any of the processes realising it (i.e. you send messages a, b,
and c, and the other side only receives messages a and c).

AEMP guarantees correct ordering, and the guarantee that there are no
holes in the message sequence.

=item * In erlang, processes can be declared dead and later be found to be
alive.

In erlang it can happen that a monitored process is declared dead and
linked processes get killed, but later it turns out that the process is
still alive - and can receive messages.

In AEMP, when port monitoring detects a port as dead, then that port will
eventually be killed - it cannot happen that a node detects a port as dead
and then later sends messages to it, finding it is still alive.

=item * Erlang can send messages to the wrong port, AEMP does not.

In erlang it is quite possible that a node that restarts reuses a process
ID known to other nodes for a completely different process, causing
messages destined for that process to end up in an unrelated process.

AEMP never reuses port IDs, so old messages or old port IDs floating
around in the network will not be sent to an unrelated port.

=item * Erlang uses unprotected connections, AEMP uses secure
authentication and can use TLS.

AEMP can use a proven protocol - SSL/TLS - to protect connections and
securely authenticate nodes.

=item * The AEMP protocol is optimised for both text-based and binary
communications.

The AEMP protocol, unlike the erlang protocol, supports both
language-independent text-only protocols (good for debugging) and binary,
language-specific serialisers (e.g. Storable).

It has also been carefully designed to be implementable in other languages
with a minimum of work while gracefully degrading fucntionality to make the
protocol simple.

=back

=head1 SEE ALSO

L<AnyEvent>.

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

1

Revision:	1.32
Committed:	Wed Aug 5 19:58:46 2009 UTC (14 years, 9 months ago) by root
Branch:	MAIN
Changes since 1.31:	+110 -109 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3			AnyEvent::MP - multi-processing/message-passing framework
4
5			=head1 SYNOPSIS
6
7			use AnyEvent::MP;
8
9	root	1.22	$NODE # contains this node's noderef
10			NODE # returns this node's noderef
11			NODE $port # returns the noderef of the port
12	root	1.2
13			snd $port, type => data...;
14
15	root	1.22	$SELF # receiving/own port id in rcv callbacks
16
17	root	1.2	rcv $port, smartmatch => $cb->($port, @msg);
18
19			# examples:
20			rcv $port2, ping => sub { snd $_[0], "pong"; 0 };
21			rcv $port1, pong => sub { warn "pong received\n" };
22			snd $port2, ping => $port1;
23
24			# more, smarter, matches (_any_ is exported by this module)
25			rcv $port, [child_died => $pid] => sub { ...
26			rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27
28	root	1.1	=head1 DESCRIPTION
29
30	root	1.2	This module (-family) implements a simple message passing framework.
31
32			Despite its simplicity, you can securely message other processes running
33			on the same or other hosts.
34
35	root	1.23	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36			manual page.
37
38			At the moment, this module family is severly broken and underdocumented,
39	root	1.21	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	root	1.23	stay tuned! The basic API should be finished, however.
41	root	1.6
42	root	1.2	=head1 CONCEPTS
43
44			=over 4
45
46			=item port
47
48	root	1.29	A port is something you can send messages to (with the C<snd> function).
49
50			Some ports allow you to register C<rcv> handlers that can match specific
51			messages. All C<rcv> handlers will receive messages they match, messages
52			will not be queued.
53	root	1.2
54	root	1.3	=item port id - C<noderef#portname>
55	root	1.2
56	root	1.29	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
57			separator, and a port name (a printable string of unspecified format). An
58	root	1.30	exception is the the node port, whose ID is identical to its node
59	root	1.29	reference.
60	root	1.2
61			=item node
62
63			A node is a single process containing at least one port - the node
64	root	1.29	port. You can send messages to node ports to find existing ports or to
65			create new ports, among other things.
66	root	1.2
67	root	1.29	Nodes are either private (single-process only), slaves (connected to a
68			master node only) or public nodes (connectable from unrelated nodes).
69	root	1.2
70	root	1.5	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
71	root	1.2
72	root	1.29	A node reference is a string that either simply identifies the node (for
73			private and slave nodes), or contains a recipe on how to reach a given
74	root	1.2	node (for public nodes).
75
76	root	1.29	This recipe is simply a comma-separated list of C<address:port> pairs (for
77			TCP/IP, other protocols might look different).
78
79			Node references come in two flavours: resolved (containing only numerical
80			addresses) or unresolved (where hostnames are used instead of addresses).
81
82			Before using an unresolved node reference in a message you first have to
83			resolve it.
84
85	root	1.2	=back
86
87	root	1.3	=head1 VARIABLES/FUNCTIONS
88	root	1.2
89			=over 4
90
91	root	1.1	=cut
92
93			package AnyEvent::MP;
94
95	root	1.8	use AnyEvent::MP::Base;
96	root	1.2
97	root	1.1	use common::sense;
98
99	root	1.2	use Carp ();
100
101	root	1.1	use AE ();
102
103	root	1.2	use base "Exporter";
104
105	root	1.25	our $VERSION = '0.1';
106	root	1.8	our @EXPORT = qw(
107	root	1.22	NODE $NODE *SELF node_of _any_
108	root	1.31	resolve_node initialise_node
109	root	1.22	snd rcv mon kil reg psub
110			port
111	root	1.8	);
112	root	1.2
113	root	1.22	our $SELF;
114
115			sub _self_die() {
116			my $msg = $@;
117			$msg =~ s/\n+$// unless ref $msg;
118			kil $SELF, die => $msg;
119			}
120
121			=item $thisnode = NODE / $NODE
122
123			The C<NODE> function returns, and the C<$NODE> variable contains
124			the noderef of the local node. The value is initialised by a call
125			to C<become_public> or C<become_slave>, after which all local port
126			identifiers become invalid.
127
128			=item $noderef = node_of $portid
129
130			Extracts and returns the noderef from a portid or a noderef.
131
132	root	1.29	=item $cv = resolve_node $noderef
133
134			Takes an unresolved node reference that may contain hostnames and
135			abbreviated IDs, resolves all of them and returns a resolved node
136			reference.
137
138			In addition to C<address:port> pairs allowed in resolved noderefs, the
139			following forms are supported:
140
141			=over 4
142
143			=item the empty string
144
145			An empty-string component gets resolved as if the default port (4040) was
146			specified.
147
148			=item naked port numbers (e.g. C<1234>)
149
150			These are resolved by prepending the local nodename and a colon, to be
151			further resolved.
152
153			=item hostnames (e.g. C<localhost:1234>, C<localhost>)
154
155			These are resolved by using AnyEvent::DNS to resolve them, optionally
156			looking up SRV records for the C<aemp=4040> port, if no port was
157			specified.
158
159			=back
160
161	root	1.22	=item $SELF
162
163			Contains the current port id while executing C<rcv> callbacks or C<psub>
164			blocks.
165	root	1.3
166	root	1.22	=item SELF, %SELF, @SELF...
167
168			Due to some quirks in how perl exports variables, it is impossible to
169			just export C<$SELF>, all the symbols called C<SELF> are exported by this
170			module, but only C<$SELF> is currently used.
171	root	1.3
172			=item snd $portid, type => @data
173
174			=item snd $portid, @msg
175
176	root	1.8	Send the given message to the given port ID, which can identify either
177			a local or a remote port, and can be either a string or soemthignt hat
178			stringifies a sa port ID (such as a port object :).
179
180			While the message can be about anything, it is highly recommended to use a
181			string as first element (a portid, or some word that indicates a request
182			type etc.).
183	root	1.3
184			The message data effectively becomes read-only after a call to this
185			function: modifying any argument is not allowed and can cause many
186			problems.
187
188			The type of data you can transfer depends on the transport protocol: when
189			JSON is used, then only strings, numbers and arrays and hashes consisting
190			of those are allowed (no objects). When Storable is used, then anything
191			that Storable can serialise and deserialise is allowed, and for the local
192			node, anything can be passed.
193
194	root	1.22	=item $local_port = port
195	root	1.2
196	root	1.31	Create a new local port object that can be used either as a pattern
197			matching port ("full port") or a single-callback port ("miniport"),
198			depending on how C<rcv> callbacks are bound to the object.
199	root	1.3
200	root	1.22	=item $portid = port { my @msg = @_; $finished }
201	root	1.10
202	root	1.15	Creates a "mini port", that is, a very lightweight port without any
203			pattern matching behind it, and returns its ID.
204
205			The block will be called for every message received on the port. When the
206			callback returns a true value its job is considered "done" and the port
207			will be destroyed. Otherwise it will stay alive.
208
209	root	1.17	The message will be passed as-is, no extra argument (i.e. no port id) will
210	root	1.15	be passed to the callback.
211
212			If you need the local port id in the callback, this works nicely:
213
214	root	1.31	my $port; $port = port {
215	root	1.15	snd $otherport, reply => $port;
216			};
217	root	1.10
218			=cut
219
220	root	1.22	sub port(;&) {
221			my $id = "$UNIQ." . $ID++;
222			my $port = "$NODE#$id";
223
224			if (@_) {
225			my $cb = shift;
226			$PORT{$id} = sub {
227			local $SELF = $port;
228			eval {
229			&$cb
230			and kil $id;
231			};
232			_self_die if $@;
233			};
234			} else {
235			my $self = bless {
236			id => "$NODE#$id",
237			}, "AnyEvent::MP::Port";
238
239			$PORT_DATA{$id} = $self;
240			$PORT{$id} = sub {
241			local $SELF = $port;
242
243			eval {
244			for (@{ $self->{rc0}{$_[0]} }) {
245			$_ && &{$_->[0]}
246			&& undef $_;
247			}
248
249			for (@{ $self->{rcv}{$_[0]} }) {
250			$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
251			&& &{$_->[0]}
252			&& undef $_;
253			}
254
255			for (@{ $self->{any} }) {
256			$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
257			&& &{$_->[0]}
258			&& undef $_;
259			}
260			};
261			_self_die if $@;
262			};
263			}
264	root	1.10
265	root	1.22	$port
266	root	1.10	}
267
268	root	1.22	=item reg $portid, $name
269	root	1.8
270	root	1.22	Registers the given port under the name C<$name>. If the name already
271			exists it is replaced.
272	root	1.8
273	root	1.22	A port can only be registered under one well known name.
274	root	1.8
275	root	1.22	A port automatically becomes unregistered when it is killed.
276	root	1.8
277			=cut
278
279	root	1.22	sub reg(@) {
280			my ($portid, $name) = @_;
281	root	1.8
282	root	1.22	$REG{$name} = $portid;
283			}
284	root	1.18
285	root	1.31	=item rcv $portid, $callback->(@msg)
286
287			Replaces the callback on the specified miniport (or newly created port
288			object, see C<port>). Full ports are configured with the following calls:
289
290	root	1.22	=item rcv $portid, tagstring => $callback->(@msg), ...
291	root	1.3
292	root	1.22	=item rcv $portid, $smartmatch => $callback->(@msg), ...
293	root	1.3
294	root	1.22	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
295	root	1.3
296	root	1.32	Register callbacks to be called on matching messages on the given full
297			port (or newly created port).
298	root	1.3
299			The callback has to return a true value when its work is done, after
300			which is will be removed, or a false value in which case it will stay
301			registered.
302
303	root	1.22	The global C<$SELF> (exported by this module) contains C<$portid> while
304			executing the callback.
305
306			Runtime errors wdurign callback execution will result in the port being
307			C<kil>ed.
308
309	root	1.3	If the match is an array reference, then it will be matched against the
310			first elements of the message, otherwise only the first element is being
311			matched.
312
313			Any element in the match that is specified as C<_any_> (a function
314			exported by this module) matches any single element of the message.
315
316			While not required, it is highly recommended that the first matching
317			element is a string identifying the message. The one-string-only match is
318			also the most efficient match (by far).
319
320			=cut
321
322			sub rcv($@) {
323	root	1.31	my $portid = shift;
324			my ($noderef, $port) = split /#/, $port, 2;
325	root	1.3
326	root	1.22	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
327			or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
328
329			my $self = $PORT_DATA{$port}
330			or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
331
332			"AnyEvent::MP::Port" eq ref $self
333			or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
334
335			while (@_) {
336			my ($match, $cb) = splice @_, 0, 2;
337
338			if (!ref $match) {
339			push @{ $self->{rc0}{$match} }, [$cb];
340			} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
341			my ($type, @match) = @$match;
342			@match
343			? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
344			: push @{ $self->{rc0}{$match->[0]} }, [$cb];
345			} else {
346			push @{ $self->{any} }, [$cb, $match];
347			}
348	root	1.3	}
349	root	1.31
350			$portid
351	root	1.2	}
352
353	root	1.22	=item $closure = psub { BLOCK }
354	root	1.2
355	root	1.22	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
356			closure is executed, sets up the environment in the same way as in C<rcv>
357			callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
358
359			This is useful when you register callbacks from C<rcv> callbacks:
360
361			rcv delayed_reply => sub {
362			my ($delay, @reply) = @_;
363			my $timer = AE::timer $delay, 0, psub {
364			snd @reply, $SELF;
365			};
366			};
367	root	1.3
368	root	1.8	=cut
369	root	1.3
370	root	1.22	sub psub(&) {
371			my $cb = shift;
372	root	1.3
373	root	1.22	my $port = $SELF
374			or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
375	root	1.1
376	root	1.22	sub {
377			local $SELF = $port;
378	root	1.2
379	root	1.22	if (wantarray) {
380			my @res = eval { &$cb };
381			_self_die if $@;
382			@res
383			} else {
384			my $res = eval { &$cb };
385			_self_die if $@;
386			$res
387			}
388			}
389	root	1.2	}
390
391	root	1.32	=item $guard = mon $portid, $cb->(@reason)
392
393			=item $guard = mon $portid, $otherport
394
395			=item $guard = mon $portid, $otherport, @msg
396
397			Monitor the given port and do something when the port is killed.
398
399			In the first form, the callback is simply called with any number
400			of C<@reason> elements (no @reason means that the port was deleted
401			"normally"). Note also that I<< the callback B<must> never die >>, so use
402			C<eval> if unsure.
403
404			In the second form, the other port will be C<kil>'ed with C<@reason>, iff
405			a @reason was specified, i.e. on "normal" kils nothing happens, while
406			under all other conditions, the other port is killed with the same reason.
407
408			In the last form, a message of the form C<@msg, @reason> will be C<snd>.
409
410			Example: call a given callback when C<$port> is killed.
411
412			mon $port, sub { warn "port died because of <@_>\n" };
413
414			Example: kill ourselves when C<$port> is killed abnormally.
415
416			mon $port, $self;
417
418			Example: send us a restart message another C<$port> is killed.
419
420			mon $port, $self => "restart";
421
422			=cut
423
424			sub mon {
425			my ($noderef, $port) = split /#/, shift, 2;
426
427			my $node = $NODE{$noderef} \|\| add_node $noderef;
428
429			my $cb = shift;
430
431			unless (ref $cb) {
432			if (@_) {
433			# send a kill info message
434			my (@msg) = ($cb, @_);
435			$cb = sub { snd @msg, @_ };
436			} else {
437			# simply kill other port
438			my $port = $cb;
439			$cb = sub { kil $port, @_ if @_ };
440			}
441			}
442
443			$node->monitor ($port, $cb);
444
445			defined wantarray
446			and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
447			}
448
449			=item $guard = mon_guard $port, $ref, $ref...
450
451			Monitors the given C<$port> and keeps the passed references. When the port
452			is killed, the references will be freed.
453
454			Optionally returns a guard that will stop the monitoring.
455
456			This function is useful when you create e.g. timers or other watchers and
457			want to free them when the port gets killed:
458
459			$port->rcv (start => sub {
460			my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
461			undef $timer if 0.9 < rand;
462			});
463			});
464
465			=cut
466
467			sub mon_guard {
468			my ($port, @refs) = @_;
469
470			mon $port, sub { 0 && @refs }
471			}
472
473			=item lnk $port1, $port2
474
475			Link two ports. This is simply a shorthand for:
476
477			mon $port1, $port2;
478			mon $port2, $port1;
479
480			It means that if either one is killed abnormally, the other one gets
481			killed as well.
482
483			=item kil $portid[, @reason]
484
485			Kill the specified port with the given C<@reason>.
486
487			If no C<@reason> is specified, then the port is killed "normally" (linked
488			ports will not be kileld, or even notified).
489
490			Otherwise, linked ports get killed with the same reason (second form of
491			C<mon>, see below).
492
493			Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
494			will be reported as reason C<< die => $@ >>.
495
496			Transport/communication errors are reported as C<< transport_error =>
497			$message >>.
498
499	root	1.8	=back
500
501			=head1 FUNCTIONS FOR NODES
502
503			=over 4
504	root	1.2
505	root	1.29	=item become_public $noderef
506	root	1.8
507			Tells the node to become a public node, i.e. reachable from other nodes.
508
509	root	1.29	The first argument is the (unresolved) node reference of the local node
510			(if missing then the empty string is used).
511
512			It is quite common to not specify anything, in which case the local node
513			tries to listen on the default port, or to only specify a port number, in
514			which case AnyEvent::MP tries to guess the local addresses.
515	root	1.2
516	root	1.8	=cut
517	root	1.1
518	root	1.4	=back
519
520			=head1 NODE MESSAGES
521
522	root	1.5	Nodes understand the following messages sent to them. Many of them take
523			arguments called C<@reply>, which will simply be used to compose a reply
524			message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
525			the remaining arguments are simply the message data.
526	root	1.4
527	root	1.29	While other messages exist, they are not public and subject to change.
528
529	root	1.4	=over 4
530
531			=cut
532
533	root	1.22	=item lookup => $name, @reply
534	root	1.3
535	root	1.8	Replies with the port ID of the specified well-known port, or C<undef>.
536	root	1.3
537	root	1.7	=item devnull => ...
538
539			Generic data sink/CPU heat conversion.
540
541	root	1.4	=item relay => $port, @msg
542
543			Simply forwards the message to the given port.
544
545			=item eval => $string[ @reply]
546
547			Evaluates the given string. If C<@reply> is given, then a message of the
548	root	1.5	form C<@reply, $@, @evalres> is sent.
549
550			Example: crash another node.
551
552			snd $othernode, eval => "exit";
553	root	1.4
554			=item time => @reply
555
556			Replies the the current node time to C<@reply>.
557
558	root	1.5	Example: tell the current node to send the current time to C<$myport> in a
559			C<timereply> message.
560
561			snd $NODE, time => $myport, timereply => 1, 2;
562			# => snd $myport, timereply => 1, 2, <time>
563
564	root	1.2	=back
565
566	root	1.26	=head1 AnyEvent::MP vs. Distributed Erlang
567
568	root	1.27	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
569			== aemp node, erlang process == aemp port), so many of the documents and
570			programming techniques employed by erlang apply to AnyEvent::MP. Here is a
571			sample:
572
573			http://www.erlang.se/doc/programming_rules.shtml
574			http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
575			http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
576			http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
577
578			Despite the similarities, there are also some important differences:
579	root	1.26
580			=over 4
581
582			=item * Node references contain the recipe on how to contact them.
583
584			Erlang relies on special naming and DNS to work everywhere in the
585			same way. AEMP relies on each node knowing it's own address(es), with
586			convenience functionality.
587
588	root	1.27	This means that AEMP requires a less tightly controlled environment at the
589			cost of longer node references and a slightly higher management overhead.
590
591	root	1.26	=item * Erlang uses processes and a mailbox, AEMP does not queue.
592
593			Erlang uses processes that selctively receive messages, and therefore
594			needs a queue. AEMP is event based, queuing messages would serve no useful
595			purpose.
596
597			(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).
598
599			=item * Erlang sends are synchronous, AEMP sends are asynchronous.
600
601			Sending messages in erlang is synchronous and blocks the process. AEMP
602			sends are immediate, connection establishment is handled in the
603			background.
604
605			=item * Erlang can silently lose messages, AEMP cannot.
606
607			Erlang makes few guarantees on messages delivery - messages can get lost
608			without any of the processes realising it (i.e. you send messages a, b,
609			and c, and the other side only receives messages a and c).
610
611			AEMP guarantees correct ordering, and the guarantee that there are no
612			holes in the message sequence.
613
614			=item * In erlang, processes can be declared dead and later be found to be
615			alive.
616
617			In erlang it can happen that a monitored process is declared dead and
618			linked processes get killed, but later it turns out that the process is
619			still alive - and can receive messages.
620
621			In AEMP, when port monitoring detects a port as dead, then that port will
622			eventually be killed - it cannot happen that a node detects a port as dead
623			and then later sends messages to it, finding it is still alive.
624
625			=item * Erlang can send messages to the wrong port, AEMP does not.
626
627			In erlang it is quite possible that a node that restarts reuses a process
628			ID known to other nodes for a completely different process, causing
629			messages destined for that process to end up in an unrelated process.
630
631			AEMP never reuses port IDs, so old messages or old port IDs floating
632			around in the network will not be sent to an unrelated port.
633
634			=item * Erlang uses unprotected connections, AEMP uses secure
635			authentication and can use TLS.
636
637			AEMP can use a proven protocol - SSL/TLS - to protect connections and
638			securely authenticate nodes.
639
640	root	1.28	=item * The AEMP protocol is optimised for both text-based and binary
641			communications.
642
643			The AEMP protocol, unlike the erlang protocol, supports both
644			language-independent text-only protocols (good for debugging) and binary,
645			language-specific serialisers (e.g. Storable).
646
647			It has also been carefully designed to be implementable in other languages
648			with a minimum of work while gracefully degrading fucntionality to make the
649			protocol simple.
650
651	root	1.26	=back
652
653	root	1.1	=head1 SEE ALSO
654
655			L<AnyEvent>.
656
657			=head1 AUTHOR
658
659			Marc Lehmann <schmorp@schmorp.de>
660			http://home.schmorp.de/
661
662			=cut
663
664			1
665