buffermanager.h

我们自己写的miniSQL代码

// BufferManager.h: interface for the BufferManager class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_BUFFERMANAGER_H__9600F8CE_F199_4B7C_B709_C5FEB9B8EA85__INCLUDED_)
#define AFX_BUFFERMANAGER_H__9600F8CE_F199_4B7C_B709_C5FEB9B8EA85__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#define BLOCK_SIZE (4 * 1024)
#define BLOCK_TABLE_SIZE (1024 * 1024)
#define IN_MEM_SIZE (1024 * 1024)
#define IN_MEM_BLOCKS (IN_MEM_SIZE / BLOCK_SIZE)

class BufferManager  
{
public:
	BufferManager();
	virtual ~BufferManager();

private:
	int fileDesc;
	char *buffer;
	struct BlockEntry
	{
		unsigned inMemLocation : 16;
		unsigned dirtyFlag : 1;
		unsigned lockedFlag : 1;
	} *blockTable; 
	int *inMemQueue; 
	int front, rear, qsize;
	int *usedTable;

private:	
	int findReplacement();
	void dequeue();
	void enqueue(int blockNum);
	int bringBlock(int blockNum, int inMem);
	int seekBlock(int blockNum);
	int flushBlock(int blockNum);
	bool isQueueEmpty();
	bool isQueueFull();
	int removeBlock();
	long getFileSize();

public:
	int unlockBlock(int blockNum);
	int lockBlock(int blockNum);
	int finalize();
	int writeBlock(int blockNum);
	int initialize(char *dataFile);
	char *readBlock(int blockNum);

};

#endif // !defined(AFX_BUFFERMANAGER_H__9600F8CE_F199_4B7C_B709_C5FEB9B8EA85__INCLUDED_)