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* EOControl/EOMultiReaderLock.[h/m]: New files.
* EOControl/EOControl.h: Add EOMultiReaderLock.h. * EOControl/GNUmakefile: Add EOMultiReaderLock.h/m. git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/gdl2/trunk@22176 72102866-910b-0410-8b05-ffd578937521
This commit is contained in:
David Ayers
parent
e69eb8938e
commit
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5 changed files with 333 additions and 0 deletions
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@ -2,6 +2,10 @@
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* AUTHORS: Add Matt Rice.
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* GDL2.gsdoc: Ditto.
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* EOControl/EOMultiReaderLock.[h/m]: New files.
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* EOControl/EOControl.h: Add EOMultiReaderLock.h.
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* EOControl/GNUmakefile: Add EOMultiReaderLock.h/m.
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2005-12-05 David Ayers <d.ayers@inode.at>
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@ -47,6 +47,7 @@
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#include <EOControl/EOArrayDataSource.h>
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#include <EOControl/EODetailDataSource.h>
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#include <EOControl/EOObserver.h>
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#include <EOControl/EOMultiReaderLock.h>
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#include <EOControl/EODebug.h>
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68
EOControl/EOMultiReaderLock.h
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68
EOControl/EOMultiReaderLock.h
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@ -0,0 +1,68 @@
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/* -*-objc-*-
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EOMultiReaderLock.h
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Copyright (C) 2005 Free Software Foundation, Inc.
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Author: David Ayers <d.ayers@inode.at>
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Date: November 2005
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This file is part of the GNUstep Database Library.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; see the file COPYING.LIB.
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If not, write to the Free Software Foundation,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef __EOControl_EOMultiReaderLock_h__
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#define __EOControl_EOMultiReaderLock_h__
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#ifdef GNUSTEP
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#include <Foundation/NSObject.h>
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#include <Foundation/NSMapTable.h>
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#else
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#include <Foundation/Foundation.h>
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#endif
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@class NSConditionLock;
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@class NSThread;
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/*
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* WARNING !!!
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* This class is in the middle of it's initial experimental implementation
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* Do not use it yet! But if you'd like to help implementing, please
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* feel free.
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*/
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@interface EOMultiReaderLock : NSObject
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{
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NSConditionLock *_mutex;
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int _readerFinishedCondition;
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int _writerFinishedCondition;
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NSMapTable *_readerThreads;
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unsigned int _writerLockCount;
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volatile NSThread *_writerLockThread;
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}
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- (BOOL)tryLockForReading;
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- (void)lockForReading;
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- (void)unlockForReading;
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- (BOOL)tryLockForWriting;
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- (void)lockForWriting;
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- (void)unlockForWriting;
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- (void)suspendReaderLocks;
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- (void)retrieveReaderLocks;
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@end
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#endif
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258
EOControl/EOMultiReaderLock.m
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258
EOControl/EOMultiReaderLock.m
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@ -0,0 +1,258 @@
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/* -*-objc-*-
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EOMultiReaderLock.m
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Copyright (C) 2005 Free Software Foundation, Inc.
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Author: David Ayers <d.ayers@inode.at>
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Date: November 2005
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This file is part of the GNUstep Database Library.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; see the file COPYING.LIB.
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If not, write to the Free Software Foundation,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "EOMultiReaderLock.h"
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#ifndef GNUSTEP
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#include <GNUstepBase/GNUstep.h>
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#include <GNUstepBase/GSCategories.h>
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#include <Foundation/Foundation.h>
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#else
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#include <Foundation/NSLock.h>
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#include <Foundation/NSThread.h>
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#include <Foundation/NSMapTable.h>
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#endif
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#define LCK_CND_UNLOCKD 0
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#define LCK_CND_READING 1
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#define LCK_CND_WAITWRT 2
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#define LCK_CND_WRITING 3
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#define LCK_CND_ALLOW_READER_LOCK 0
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#define LCK_CND_ALLOW_WRITER_LOCK 1
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/**
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* WARNING !!!
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* This class is in the middle of its initial experimental implementation
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* Do not use it yet! But if you'd like to help implementing, please
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* feel free.
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* EOMultiReaderLock is a recursive lock which allows multiple
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* threads to hold a lock for reading but only one thread
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* to hold a lock for writing and only when all reading locks
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* have been relinquished. Once thread requests for a lock to write
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* further requests for a read lock are blocked until the write lock
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* has been granted and relinquished again. But this only holds true
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* if the thread requesting the reading lock does not already hold
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* a reading lock in which case it is granted as it is assumed that
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* this thread needs to continue to release the previously acquired lock
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* or locks.
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*/
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@implementation EOMultiReaderLock
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- (id)init
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{
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if ((self = [super init]))
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{
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_mutex = [NSConditionLock initWithCondition: LCK_CND_UNLOCKD];
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_readerThreads = NSCreateMapTable(NSNonOwnedPointerMapKeyCallBacks,
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NSIntMapValueCallBacks, 32);
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}
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return self;
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}
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/**
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* <p>Tries to obtain a lock for reading. Returns NO upon failure.</p>
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* <p>If the thread already holds this lock for reading or writing
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* the method returns true. All successful locks must be paired with
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* corresponding unlocks.</p>
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*/
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- (BOOL)tryLockForReading
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{
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NSThread *ct = [NSThread currentThread];
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int cnt = (int)NSMapGet(_readerThreads,ct);
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BOOL flag;
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if (ct == _writerLockThread)
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{
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NSMapInsert(_readerThreads,ct,(void *)(++cnt));
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return YES;
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}
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if (cnt > 0)
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{
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NSMapInsert(_readerThreads,ct,(void *)(++cnt));
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return YES;
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}
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if ((flag = [_mutex tryLock]))
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{
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if (_writerLockThread)
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{
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flag = NO;
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}
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else
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{
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NSMapInsert(_readerThreads,ct,(void *)(++cnt));
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flag = YES;
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}
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[_mutex unlock];
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}
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return flag;
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}
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/**
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* <p>Blocks until a lock for reading is obtained.</p>
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* <p>If the thread already holds this lock for reading or writing
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* the method returns immediatly. All successful locks must be paired with
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* corresponding unlocks.</p>
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*/
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- (void)lockForReading
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{
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NSThread *ct = [NSThread currentThread];
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int cnt = (int)NSMapGet(_readerThreads,ct);
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if (ct == _writerLockThread)
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{
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NSMapInsert(_readerThreads,ct,(void *)(++cnt));
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return;
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}
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if (cnt > 0)
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{
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NSMapInsert(_readerThreads,ct,(void *)(++cnt));
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return;
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}
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while (1)
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{
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[_mutex lock];
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if (_writerLockThread)
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{
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[_mutex unlock];
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continue;
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}
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else
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{
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NSMapInsert(_readerThreads,ct,(void *)(++cnt));
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[_mutex unlock];
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break;
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}
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}
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}
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/**
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* <p>Relinquishes obtained a previously obtained lock for reading.</p>
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* <p>If the thread already holds this lock for reading or writing
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* the method returns immediatly. All successful locks must be paired with
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* corresponding unlocks.</p>
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*/
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- (void)unlockForReading
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{
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NSThread *ct = [NSThread currentThread];
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int cnt = (int)NSMapGet(_readerThreads,ct);
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if (--cnt)
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{
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NSMapInsert(_readerThreads,ct,(void *)(cnt));
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}
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else
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{
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NSMapRemove(_readerThreads,ct);
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}
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}
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/**
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* <p>Tries to obtain a lock for writing. Returns NO upon failure.</p>
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* <p>If the thread already holds this lock for reading or writing
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* the method returns true. All successful locks must be paired with
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* corresponding unlocks.</p>
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*/
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- (BOOL)tryLockForWriting
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{
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NSThread *ct = [NSThread currentThread];
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if (ct == _writerLockThread)
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{
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_writerLockCount++;
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return YES;
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}
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if (_writerLockThread) return NO;
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if ([_mutex tryLock])
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{
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int entries;
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if (_writerLockThread)
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{
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[_mutex unlock];
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return NO;
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}
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entries = (int)NSCountMapTable(_readerThreads);
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if (entries > 1)
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{
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[_mutex unlock];
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return NO;
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}
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if (entries == 0 || NSMapGet(_readerThreads,ct))
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{
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_writerLockThread = ct;
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_writerLockCount = 1;
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[_mutex unlock];
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return YES;
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}
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[_mutex unlock];
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return NO;
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}
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return NO;
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}
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/**
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* <p>Blocks until a lock for writing is obtained.</p>
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* <p>If the thread already holds this lock for reading or writing
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* the method returns immediatly. All successful locks must be paired with
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* corresponding unlocks.</p>
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*/
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- (void)lockForWriting
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{
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}
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/**
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* <p>Relinquishes obtained a previously obtained lock for writing.</p>
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* <p>If the thread already holds this lock for reading or writing
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* the method returns immediatly. All successful locks must be paired with
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* corresponding unlocks.</p>
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*/
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- (void)unlockForWriting
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{
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}
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/**
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* <p>Disables the currently registered reader locks.</p>
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* <p>Subsequent calls may increment the count for it's thread
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* but the lock is not reactivated.</p>
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*/
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- (void)suspendReaderLocks
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{
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}
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/**
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* <p>Reenables the current registred locks.</p>
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* <p>This method blocks as long as a writer lock is held by
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* another thread.</p>
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*/
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- (void)retrieveReaderLocks
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{
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}
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@end
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@ -67,6 +67,7 @@ EOMutableKnownKeyDictionary.m \
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EONSAddOns.m \
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EOCheapArray.m \
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EOArrayDataSource.m \
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EOMultiReaderLock.m \
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EODebug.m \
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EOPrivate.m
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@ -93,6 +94,7 @@ EOSharedEditingContext.h \
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EODataSource.h \
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EODetailDataSource.h \
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EOArrayDataSource.h \
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EOMultiReaderLock.h \
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EODebug.h \
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EONSAddOns.h \
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EODefines.h \
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