mirror of
https://github.com/FirebirdSQL/firebird.git
synced 2025-01-27 17:23:03 +01:00
112 lines
3.0 KiB
C++
112 lines
3.0 KiB
C++
/*
|
|
* PROGRAM: JRD Access Method
|
|
* MODULE: GlobalRWLock.h
|
|
* DESCRIPTION: Global Read Write Lock
|
|
*
|
|
* The contents of this file are subject to the Initial
|
|
* Developer's Public License Version 1.0 (the "License");
|
|
* you may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at
|
|
* http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_idpl.
|
|
*
|
|
* Software distributed under the License is distributed AS IS,
|
|
* WITHOUT WARRANTY OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing rights
|
|
* and limitations under the License.
|
|
*
|
|
* The Original Code was created by Nickolay Samofatov
|
|
* for the Firebird Open Source RDBMS project.
|
|
*
|
|
* Copyright (c) 2006 Nickolay Samofatov
|
|
* and all contributors signed below.
|
|
*
|
|
* All Rights Reserved.
|
|
* Contributor(s):
|
|
*
|
|
* Roman Simakov <roman-simakov@users.sourceforge.net>
|
|
*
|
|
*/
|
|
|
|
#ifndef GLOBAL_RW_LOCK
|
|
#define GLOBAL_RW_LOCK
|
|
|
|
#include "../common/classes/alloc.h"
|
|
#include "../jrd/jrd.h"
|
|
#include "../jrd/lck.h"
|
|
#include "../jrd/lck_proto.h"
|
|
#include "../include/fb_types.h"
|
|
#include "os/pio.h"
|
|
#include "../common/classes/condition.h"
|
|
|
|
//#define COS_DEBUG
|
|
|
|
#ifdef COS_DEBUG
|
|
DEFINE_TRACE_ROUTINE(cos_trace);
|
|
#define COS_TRACE(args) cos_trace args
|
|
#define COS_TRACE_AST(message) gds__trace(message)
|
|
#else
|
|
#define COS_TRACE(args) /* nothing */
|
|
#define COS_TRACE_AST(message) /* nothing */
|
|
#endif
|
|
|
|
|
|
namespace Jrd {
|
|
|
|
typedef USHORT locktype_t;
|
|
|
|
class GlobalRWLock : public Firebird::PermanentStorage
|
|
{
|
|
public:
|
|
GlobalRWLock(thread_db* tdbb, MemoryPool& p, locktype_t lckType,
|
|
lck_owner_t lock_owner, bool lock_caching = true,
|
|
size_t lockLen = 0, const UCHAR* lockStr = NULL);
|
|
|
|
virtual ~GlobalRWLock();
|
|
|
|
// This function returns false if it cannot take the lock
|
|
bool lockWrite(thread_db* tdbb, SSHORT wait);
|
|
void unlockWrite(thread_db* tdbb);
|
|
bool lockRead(thread_db* tdbb, SSHORT wait, const bool queueJump = false);
|
|
void unlockRead(thread_db* tdbb);
|
|
bool tryReleaseLock(thread_db* tdbb);
|
|
void shutdownLock();
|
|
|
|
protected:
|
|
// Flag to indicate that somebody is waiting via lock manager.
|
|
// If somebody uses lock manager, all concurrent requests should also
|
|
// go via lock manager to prevent starvation.
|
|
Lock* cachedLock;
|
|
|
|
// Load the object from shared location.
|
|
virtual bool fetch(thread_db* /*tdbb*/) { return true; }
|
|
virtual void invalidate(thread_db* /*tdbb*/)
|
|
{
|
|
fb_assert(readers == 0);
|
|
blocking = false;
|
|
}
|
|
|
|
virtual void blockingAstHandler(thread_db* tdbb);
|
|
|
|
private:
|
|
Firebird::Mutex counterMutex; // Protects counter and blocking flag
|
|
ULONG pendingLock;
|
|
|
|
ULONG readers;
|
|
Firebird::Condition noReaders; // Semaphore to wait all readers unlock to start relock
|
|
|
|
ULONG pendingWriters;
|
|
bool currentWriter;
|
|
Firebird::Condition writerFinished;
|
|
|
|
// true - unlock keep cached lock and release by AST.
|
|
// false - unlock releases cached lock if possible
|
|
bool lockCaching;
|
|
bool blocking; // Unprocessed AST pending
|
|
|
|
static int blocking_ast_cached_lock(void* ast_object);
|
|
};
|
|
|
|
}
|
|
|
|
#endif // GLOBAL_RW_LOCK
|