/Users/green/Documents/workspace/DavisDB_public/PageFileManager.h

/*
 * PF_Manager.h
 *
 *  Created on: Mar 15, 2010
 *      Author: green
 */

#ifndef PAGEFILE_MANAGER_H_
#define PAGEFILE_MANAGER_H_

#include "Common.h"
#include <list>

class FileHandle;

class PageBlock {
private:
        friend class PageFileManager;

        PageBlock();
        ~PageBlock();

        void clear();
        bool isConsistent();
        int pin();
        int unpin();

        bool isFree_;
        int pinCount_;
        bool isDirty_;
        FileHandle* fileHandle_;
        int pageNo_;
        long epoch_;
        char data_[PF_PAGE_SIZE];
        ulong guard_;

        static const ulong GUARD_VALUE = ULONG_MAX;
};




class PageFileManager {
public:
        ReturnCode createFile(const char *fileName);

        ReturnCode removeFile(const char *fileName);

        ReturnCode openFile(const char *fileName, FileHandle **fileHandle);

        ReturnCode closeFile(FileHandle *fileHandle);

        ReturnCode allocateBlock(char **buffer);

        ReturnCode disposeBlock(char *buffer);

        ReturnCode lookupBlock(FileHandle* fileHandle, int pageNo, char** data);

        ReturnCode setBlockDirty(FileHandle* fileHandle, int pageNo, bool isDirty);

        ReturnCode getBlockDirty(FileHandle* fileHandle, int pageNo, bool *isDirty);

        ReturnCode allocateBlock(FileHandle* fileHandle, int pageNo, char** data);

        ReturnCode disposeBlock(FileHandle* fileHandle, int pageNo);

        ReturnCode unpinBlock(FileHandle* fileHandle, int pageNo);

        ReturnCode getDirtyPageNumber(FileHandle* fileHandle, int* pageNo);

        ReturnCode getPinCount(FileHandle* fileHandle, int pageNo, int* pinCount);

        static PageFileManager* getInstance();

private:
        PageFileManager();

        ~PageFileManager();

        long nextEpoch();
        PageBlock* getPageBlock(char* data);
        PageBlock* getPageBlock(FileHandle* fileHandle, int pageNo);
        void disposePageBlock(PageBlock* pageBlock);
        void setPageBlock(PageBlock* pageBlock, FileHandle* fileHandle, int pageNo,
                        char** data);
        bool hasPinnedPage(FileHandle* fileHandle);

        std::list<FileHandle*> openFileList_;           // the list of open files
        PageBlock pageBlocks_[PF_BUFFER_SIZE];
        long nEpoch_;
};

#endif /* PAGEFILE_MANAGER_H_ */

---