/**
 * Copyright - See the COPYRIGHT that is included with this distribution.
 * pvAccessCPP is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution.
 */
 
#ifndef REFERENCECOUNTINGLOCK_H
#define REFERENCECOUNTINGLOCK_H

#ifdef epicsExportSharedSymbols
#   define referenceCountingLockEpicsExportSharedSymbols
#   undef epicsExportSharedSymbols
#endif

#include <pv/lock.h>
#include <pv/pvType.h>
#include <pv/sharedPtr.h>

#ifdef referenceCountingLockEpicsExportSharedSymbols
#   define epicsExportSharedSymbols
#	undef referenceCountingLockEpicsExportSharedSymbols
#endif

namespace epics {
namespace pvAccess {

/**
 * Reference counting mutex implementation w/ deadlock detection.
 * Synchronization helper class used (intended for use) for activation/deactivation synchronization.
 * This class enforces <code>attempt</code> method of acquiring the locks to prevent deadlocks.
 * Class also offers reference counting.
 * (NOTE: automatic lock counting was not implemented due to imperfect usage.)
 *
 */
class ReferenceCountingLock
{
public:
    POINTER_DEFINITIONS(ReferenceCountingLock);

	/**
	 * Constructor of <code>ReferenceCountingLock</code>.
	 * After construction lock is free and reference count equals <code>1</code>.
	 */
	ReferenceCountingLock();
	/**
	 * Destructor of <code>ReferenceCountingLock</code>.
	 */
	virtual ~ReferenceCountingLock();
	/**
	 * Attempt to acquire lock.
	 *
	 * NOTE: Argument msecs is currently not supported due to
	 * Darwin OS not supporting pthread_mutex_timedlock. May be changed in the future.
	 *
	 * @param	msecs	the number of milleseconds to wait.
	 * 					An argument less than or equal to zero means not to wait at all.
	 *
	 * @return	<code>true</code> if acquired, <code>false</code> otherwise.
	 * 			NOTE: currently this routine always returns true. Look above for explanation.
	 *
	 */
	bool acquire(epics::pvData::int64 msecs);
	/**
	 * Release previously acquired lock.
	 */
	void release();
	/**
	 * Increment number of references.
	 *
	 * @return number of references.
	 */
	int increment();
	/**
	 * Decrement number of references.
	 *
	 * @return number of references.
	 */
	int decrement();
private:
	int _references;
	epics::pvData::Mutex _mutex;
	epics::pvData::Mutex _countMutex;
};

}}

#endif  /* REFERENCECOUNTINGLOCK_H */