SegPageBackupRestoreDevice.h

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/*
// $Id: //open/dev/fennel/segment/SegPageBackupRestoreDevice.h#6 $
// Fennel is a library of data storage and processing components.
// Copyright (C) 2005-2009 The Eigenbase Project
// Copyright (C) 2005-2009 SQLstream, Inc.
// Copyright (C) 2005-2009 LucidEra, Inc.
// Portions Copyright (C) 1999-2009 John V. Sichi
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 of the License, or (at your option)
// any later version approved by The Eigenbase Project.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#ifndef Fennel_SegPageBackupRestoreDevice_Included
#define Fennel_SegPageBackupRestoreDevice_Included

#include "fennel/common/ClosableObject.h"
#include "fennel/common/FennelExcn.h"
#include "fennel/synch/SynchObj.h"
#include "fennel/device/RandomAccessRequest.h"
#include "fennel/segment/SegPageLock.h"

#include <vector>
#include <boost/enable_shared_from_this.hpp>
#include <boost/scoped_array.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/utility.hpp>

FENNEL_BEGIN_NAMESPACE

class FENNEL_SEGMENT_EXPORT BackupRestorePage
    : public RandomAccessRequestBinding
{
    PBuffer pBuffer;

    BlockNum pageCounter;

    uint bufferSize;

    bool isRead;

    WeakSegPageBackupRestoreDevice pParent;

public:
    // implement RandomAccessRequestBinding
    virtual PBuffer getBuffer() const;
    virtual uint getBufferSize() const;
    virtual void notifyTransferCompletion(bool bSuccess);

    void setParent(WeakSegPageBackupRestoreDevice pParentInit);

    void setBuffer(PBuffer pBuffer);

    void setBufferSize(uint bufferSize);

    BlockNum getPageCounter();

    void setPageCounter(BlockNum counter);

    void setReadRequest(bool isRead);
};

class FENNEL_SEGMENT_EXPORT SegPageBackupRestoreDevice
    : public boost::noncopyable,
        public ClosableObject,
        public boost::enable_shared_from_this<SegPageBackupRestoreDevice>
{
    std::string backupFilePathname;

    uint nReservedPages;

    SegmentAccessor scratchAccessor;

    DeviceAccessScheduler &scheduler;

    SharedRandomAccessDevice pDataDevice;

    char *mode;

    /*
     * If non-empty string, the full path of the program to use to compress or
     * decompress the backup file
     */
    std::string compressionProgram;

    /*
     * The number of scratch pages to allocate for backing up and restoring
     * data pages
     */
    uint nScratchPages;

    bool isCompressed;

    SegPageLock scratchLock;

    FILE *backupFile;

    uint pageSize;

    boost::scoped_array<PBuffer> reservedPages;

    std::vector<BackupRestorePage *> freeScratchPageQueue;

    LocalCondition freeScratchPageCondition;

    StrictMutex mutex;

    typedef std::hash_map<BlockNum, BackupRestorePage *> PendingWriteMap;

    typedef PendingWriteMap::iterator PendingWriteMapIter;

    PendingWriteMap pendingWriteMap;

    BlockNum currPageReadCount;

    BlockNum currPageWriteCount;

    boost::scoped_array<BackupRestorePage> backupRestorePages;

    boost::scoped_ptr<FennelExcn> pPendingExcn;

    void init();

    void setCompressionProgramPathname(const std::string &programName);

    void initScratchPages(
        SegPageLock &scratchLock,
        uint nScratchPages,
        uint nReservedPages,
        uint bufferSize);

    BackupRestorePage *getFreeScratchPage();

    void freeScratchPage(BackupRestorePage &scratchPage);

    void writeBackupPage(PConstBuffer pageBuffer, bool scheduledWrite);

    void checkPendingException();

    // Implement ClosableObject
    virtual void closeImpl();

public:
    SegPageBackupRestoreDevice(
        const std::string &backupFilePathname,
        const char *mode,
        const std::string &compressionProgram,
        uint nScratchPages,
        uint nReservedPages,
        SegmentAccessor &scratchAccessor,
        DeviceAccessScheduler &scheduler,
        SharedRandomAccessDevice pDataDevice);

    static SharedSegPageBackupRestoreDevice newSegPageBackupRestoreDevice(
        const std::string &backupFilePathname,
        const char *mode,
        const std::string &compressionProgram,
        uint nScratchPages,
        uint nReservedPages,
        SegmentAccessor &scratchAccessor,
        DeviceAccessScheduler &scheduler,
        SharedRandomAccessDevice pDataDevice);

    PBuffer getReservedBufferPage();

    void writeBackupPage(PConstBuffer pageBuffer);

    void backupPage(BlockId blockId);

    void notifyReadTransferCompletion(
        BackupRestorePage &scratchPage,
        bool bSuccess);

    void restorePage(BlockId blockId);

    void notifyWriteTransferCompletion(
        BackupRestorePage &scratchPage,
        bool bSuccess);

    void waitForPendingWrites();

    StrictMutex &getMutex();
};

FENNEL_END_NAMESPACE

#endif

// End SegPageBackupRestoreDevice.h

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