OwnableSynchronizerObjectBuffer.hpp

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 * Copyright (c) 1991, 2014 IBM Corp. and others
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 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
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 * is available at https://www.apache.org/licenses/LICENSE-2.0.
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 * forth in the Eclipse Public License, v. 2.0 are satisfied: GNU
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#ifndef OWNABLESYNCHRONIZEROBJECTBUFFER_HPP_
#define OWNABLESYNCHRONIZEROBJECTBUFFER_HPP_

#include "j9.h"
#include "j9cfg.h"

#include "BaseVirtual.hpp"

class MM_EnvironmentBase;
class MM_GCExtensions;
class MM_HeapRegionDescriptor;

/**
 * A per-thread buffer of recently allocated OwnableSynchronizer objects.
 * The buffer is periodically flushed to the global list. 
 */
class MM_OwnableSynchronizerObjectBuffer : public MM_BaseVirtual
{
private:
protected:
	j9object_t _head; /**< the head of the linked list of OwnableSynchronizer objects */
	j9object_t _tail; /**< the tail of the linked list of OwnableSynchronizer objects */
	MM_HeapRegionDescriptor* _region;  /**< the region in which all buffered objects are located */
	UDATA _objectCount; /**< the number of buffered objects */
	const UDATA _maxObjectCount; /**< the maximum number of objects permitted before a forced flush */
	MM_GCExtensions * const _extensions; /**< a cached pointer to the extensions structure */
public:
	
private:
	
	/**
	 * Reset a flushed buffer to the empty state.
	 */
	void reset();

protected:

	virtual bool initialize(MM_EnvironmentBase *env) = 0;
	virtual void tearDown(MM_EnvironmentBase *env) = 0;

	/**
	 * Flush the contents of the buffer to the appropriate global buffers.
	 * Subclasses must override.
	 * @param env[in] the current thread
	 */
	virtual void flushImpl(MM_EnvironmentBase* env);
	
public:
	void kill(MM_EnvironmentBase *env);
	/**
	 * Add the specified OwnableSynchronizer object to the buffer.
	 * @param env[in] the current thread
	 * @param object[in] the object to add
	 */
	void add(MM_EnvironmentBase* env, j9object_t object);
	
	/**
	 * Flush the contents of the buffer to the appropriate global buffers.
	 * @param env[in] the current thread
	 */
	void flush(MM_EnvironmentBase* env);

	/**
	 * Construct a new buffer.
	 * @param extensions[in] the GC extensions
	 * @param maxObjectCount the maximum number of objects permitted before a forced flush 
	 */
	MM_OwnableSynchronizerObjectBuffer(MM_GCExtensions *extensions, UDATA maxObjectCount);
};

#endif /* OWNABLESYNCHRONIZEROBJECTBUFFER_HPP_ */