source: box/trunk/lib/backupstore/BackupStoreRefCountDatabase.h @ 2545

// --------------------------------------------------------------------------
//
// File
//              Name:    BackupStoreRefCountDatabase.h
//              Purpose: Main backup store information storage
//              Created: 2003/08/28
//
// --------------------------------------------------------------------------

#ifndef BACKUPSTOREREFCOUNTDATABASE__H
#define BACKUPSTOREREFCOUNTDATABASE__H

#include <memory>
#include <string>
#include <vector>

#include "BackupStoreAccountDatabase.h"
#include "FileStream.h"

class BackupStoreCheck;
class BackupStoreContext;

// set packing to one byte
#ifdef STRUCTURE_PACKING_FOR_WIRE_USE_HEADERS
#include "BeginStructPackForWire.h"
#else
BEGIN_STRUCTURE_PACKING_FOR_WIRE
#endif

typedef struct
{
        uint32_t mMagicValue;   // also the version number
        uint32_t mAccountID;
} refcount_StreamFormat;

// Use default packing
#ifdef STRUCTURE_PACKING_FOR_WIRE_USE_HEADERS
#include "EndStructPackForWire.h"
#else
END_STRUCTURE_PACKING_FOR_WIRE
#endif

// --------------------------------------------------------------------------
//
// Class
//              Name:    BackupStoreRefCountDatabase
//              Purpose: Backup store reference count database storage
//              Created: 2009/06/01
//
// --------------------------------------------------------------------------
class BackupStoreRefCountDatabase
{
        friend class BackupStoreCheck;
        friend class BackupStoreContext;
        friend class HousekeepStoreAccount;

public:
        ~BackupStoreRefCountDatabase();
private:
        // Creation through static functions only
        BackupStoreRefCountDatabase(const BackupStoreAccountDatabase::Entry&
                rAccount);
        // No copying allowed
        BackupStoreRefCountDatabase(const BackupStoreRefCountDatabase &);
        
public:
        // Create a new database for a new account. This method will refuse
        // to overwrite any existing file.
        static void CreateNew(const BackupStoreAccountDatabase::Entry& rAccount)
        {
                Create(rAccount, false);
        }
        
        // Load it from the store
        static std::auto_ptr<BackupStoreRefCountDatabase> Load(const
                BackupStoreAccountDatabase::Entry& rAccount, bool ReadOnly);
        
        typedef uint32_t refcount_t;

        // Data access functions
        refcount_t GetRefCount(int64_t ObjectID) const;
        int64_t GetLastObjectIDUsed() const;
        
        // Data modification functions
        void AddReference(int64_t ObjectID);
        // RemoveReference returns false if refcount drops to zero
        bool RemoveReference(int64_t ObjectID);

private:
        // Create a new database for an existing account. Used during
        // account checking if opening the old database throws an exception.
        // This method will overwrite any existing file.
        static void CreateForRegeneration(const
                BackupStoreAccountDatabase::Entry& rAccount)
        {
                Create(rAccount, true);
        }

        static void Create(const BackupStoreAccountDatabase::Entry& rAccount,
                bool AllowOverwrite);

        static std::string GetFilename(const BackupStoreAccountDatabase::Entry&
                rAccount);
        IOStream::pos_type GetSize() const
        {
                return mapDatabaseFile->GetPosition() +
                        mapDatabaseFile->BytesLeftToRead();
        }
        IOStream::pos_type GetEntrySize() const
        {
                return sizeof(refcount_t);
        }
        IOStream::pos_type GetOffset(int64_t ObjectID) const
        {
                return ((ObjectID - 1) * GetEntrySize()) +
                        sizeof(refcount_StreamFormat);
        }
        void SetRefCount(int64_t ObjectID, refcount_t NewRefCount);
        
        // Location information
        BackupStoreAccountDatabase::Entry mAccount;
        std::string mFilename;
        bool mReadOnly;
        bool mIsModified;
        std::auto_ptr<FileStream> mapDatabaseFile;
};

#endif // BACKUPSTOREREFCOUNTDATABASE__H