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SharedQueue.st
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1991-09-12
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"======================================================================
|
| SharedQueue Method Definitions
|
======================================================================"
"======================================================================
|
| Copyright (C) 1990, 1991 Free Software Foundation, Inc.
| Written by Steve Byrne.
|
| This file is part of GNU Smalltalk.
|
| GNU Smalltalk is free software; you can redistribute it and/or modify it
| under the terms of the GNU General Public License as published by the Free
| Software Foundation; either version 1, or (at your option) any later version.
|
| GNU Smalltalk is distributed in the hope that it will be useful, but WITHOUT
| ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
| FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
| details.
|
| You should have received a copy of the GNU General Public License along with
| GNU Smalltalk; see the file COPYING. If not, write to the Free Software
| Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
|
======================================================================"
"
| Change Log
| ============================================================================
| Author Date Change
| sbyrne 25 Apr 89 created.
|
"
Object subclass: #SharedQueue
instanceVariableNames: 'queueSem valueReady queue'
classVariableNames: ''
poolDictionaries: ''
category: nil!
SharedQueue comment:
'My instances provide a guaranteed safe mechanism to allow for communication
between processes. All access to the underlying data structures is
controlled with critical sections so that things proceed smoothly.' !
!SharedQueue class methodsFor: 'instance creation'!
new
^super new init
!!
!SharedQueue methodsFor: 'accessing'!
next
| result |
valueReady wait.
queueSem critical: [ result _ queue removeFirst ].
^result
!
nextPut: value
queueSem critical: [ queue addLast: value ].
valueReady signal.
^value
!!
!SharedQueue methodsFor: 'private'!
init
queue _ OrderedCollection new: 10.
valueReady _ Semaphore new.
queueSem _ Semaphore forMutualExclusion
!!