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/*
* Copyright (C) 2003-2006 Ben van Klinken and the CLucene Team
*
* Distributable under the terms of either the Apache License (Version 2.0) or
* the GNU Lesser General Public License, as specified in the COPYING file.
*
* Changes are Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies), all rights reserved.
*/
#ifndef _lucene_store_Lock_
#define _lucene_store_Lock_
#if defined(_LUCENE_PRAGMA_ONCE)
# pragma once
#endif
CL_NS_DEF(store)
class LuceneLock : LUCENE_BASE
{
public:
LUCENE_STATIC_CONSTANT(int64_t, LOCK_POLL_INTERVAL = 1000);
virtual ~LuceneLock() {}
// Attempts to obtain exclusive access and immediately return upon success
// or failure. Return true if exclusive access is obtained.
virtual bool obtain() = 0;
// Attempts to obtain an exclusive lock within amount of time given.
// Currently polls once per second until lockWaitTimeout is passed.
// @param lockWaitTimeout length of time to wait in ms
// @return true if lock was obtained
// @throws IOException if lock wait times out or obtain() throws an IOException
bool obtain(int64_t lockWaitTimeout);
// Release exclusive access.
virtual void release() = 0;
// Returns true if the resource is currently locked. Note that one must
// still call {@link #obtain()} before using the resource.
virtual bool isLocked() = 0;
virtual QString toString() const = 0;
};
// Utility class for executing code with exclusive access.
template<typename T>
class LuceneLockWith
{
public:
// Constructs an executor that will grab the named lock. Defaults
// lockWaitTimeout to LUCENE_COMMIT_LOCK_TIMEOUT.
// @deprecated Kept only to avoid breaking existing code.
LuceneLockWith(LuceneLock* lock, int64_t lockWaitTimeout)
{
this->lock = lock;
this->lockWaitTimeout = lockWaitTimeout;
}
virtual ~LuceneLockWith() {}
// Calls {@link #doBody} while <i>lock</i> is obtained. Blocks if lock
// cannot be obtained immediately. Retries to obtain lock once per second
// until it is obtained, or until it has tried ten times. Lock is released
// when {@link #doBody} exits.
T runAndReturn()
{
bool locked = false;
T ret = NULL;
try {
locked = lock->obtain(lockWaitTimeout);
ret = doBody();
} _CLFINALLY (
if (locked)
lock->release();
);
return ret;
}
// @see runAndReturn
// Same as runAndReturn, except doesn't return any value. The only
// difference is that no void values are used
void run()
{
bool locked = false;
try {
locked = lock->obtain(lockWaitTimeout);
doBody();
} _CLFINALLY (
if (locked)
lock->release();
);
}
protected:
virtual T doBody() = 0;
private:
LuceneLock* lock;
int64_t lockWaitTimeout;
};
CL_NS_END
#endif
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