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[urisagit/Stem.git] / lib / Stem / Event / Queue.pm
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4536f655 1# File: Stem/Event/Queue.pm
2
3# This file is part of Stem.
4# Copyright (C) 1999, 2000, 2001 Stem Systems, Inc.
5
6# Stem is free software; you can redistribute it and/or modify
7# it under the terms of the GNU General Public License as published by
8# the Free Software Foundation; either version 2 of the License, or
9# (at your option) any later version.
10
11# Stem is distributed in the hope that it will be useful,
12# but WITHOUT ANY WARRANTY; without even the implied warranty of
13# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14# GNU General Public License for more details.
15
16# You should have received a copy of the GNU General Public License
17# along with Stem; if not, write to the Free Software
18# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19
20# For a license to use the Stem under conditions other than those
21# described here, to purchase support for this software, or to purchase a
22# commercial warranty contract, please contact Stem Systems at:
23
24# Stem Systems, Inc. 781-643-7504
25# 79 Everett St. info@stemsystems.com
26# Arlington, MA 02474
27# USA
28
29# this class provides a way to deliver certain events and messages
30# synchronously with the main event loop. this is done by queueing the
31# actual event/message and writing a byte down a special pipe used
32# only inside this process. the other side of the pipe has a read
33# event that when triggered will then deliver the queued
34# events/messages.
35
36# when using Stem::Event::Signal you need to use this module as
37# well. perl signals will be delivered (safely) between perl
38# operations but they could then be delivered inside an executing
39# event handler and that means possible corruption. so this module
40# allows those signal events to be delivered by the event loop itself.
41
42
43package Stem::Event::Queue ;
44
45use strict ;
46use warnings ;
47
48use Socket;
49use IO::Handle ;
50
51use base 'Exporter' ;
52our @EXPORT = qw( &mark_not_empty ) ;
53
54my( $queue_read, $queue_write, $queue_read_event ) ;
55
56my $self ;
57
58sub _init_queue {
59
60 socketpair( $queue_read, $queue_write,
61 AF_UNIX, SOCK_STREAM, PF_UNSPEC ) || die <<DIE ;
62can't create socketpair $!
63DIE
64
65#print fileno( $queue_read ), " FILENO\n" ;
66
67 $self = bless {} ;
68
69 $queue_read->blocking( 0 ) ;
70 $queue_read_event = Stem::Event::Read->new(
71 'object' => $self,
72 'fh' => $queue_read,
73 ) ;
74
75 ref $queue_read_event or die <<DIE ;
76can't create Stem::Event::Queue read event: $queue_read_event
77DIE
78
79}
80
81my $queue_is_marked ;
82
83sub mark_not_empty {
84
85 my( $always_mark ) = @_ ;
86
87# don't mark the queue if it is already marked and we aren't forced
88# the signal queue always marks the queue
89
90 return if $queue_is_marked && !$always_mark ;
91
92 syswrite( $queue_write, 'x' ) ;
93
94 $queue_is_marked = 1 ;
95}
96
97sub readable {
98
99 sysread( $queue_read, my $buf, 10 ) ;
100
101 $queue_is_marked = 0 ;
102
103# Stem::Event::Plain::process_queue();
104 Stem::Event::Signal::process_signal_queue();
105# Stem::Msg::process_queue() if defined &Stem::Msg::process_queue;
106
107 return ;
108}
109
1101 ;