jens@0: /*
jens@0:  *  VersionDictionary.h
jens@0:  *  Ottoman
jens@0:  *
jens@0:  *  Created by Jens Alfke on 8/21/09.
jens@0:  *  Copyright 2009 Jens Alfke. All rights reserved.
jens@0:  *  BSD-Licensed: See the file "LICENSE.txt" for details.
jens@0:  */
jens@0: 
jens@0: #ifndef _MOOSEYARD_VERSIONDICTIONARY_
jens@0: #define _MOOSEYARD_VERSIONDICTIONARY_
jens@0: #include "Dictionary.h"
jens@0: 
jens@0: namespace Mooseyard {
jens@0:     
jens@0:     class File;
jens@0:     class Index;
jens@0:     
jens@0:     /** A persistent Dictionary embedded in a memory-mapped file, 
jens@0:         representing one complete version of an Ottoman dictionary. */
jens@0:     class VersionDictionary :public Dictionary {
jens@0:     public:
jens@0:         
jens@0:         /** The generation number. The first version in a new file is zero. */
jens@0:         int generation() const;
jens@0:         
jens@0:         /** The absolute time at which this version was written to the file. */
jens@0:         time_t timestamp() const;
jens@0:         
jens@0:         /** The previous version, before this one was saved. */
jens@0:         const VersionDictionary* previousVersion() const;
jens@0:         
jens@0:         /** Is this the latest version in the file? */
jens@0:         bool isLatestVersion() const;
jens@0:         
jens@0:         virtual int count() const;
jens@0:         virtual Blob get (Key) const;
jens@0:         class Iterator;
jens@0:         virtual Dictionary::Iterator* iterate() const;
jens@0:         
jens@0:         class ChangeIterator;
jens@0:         /** Iterates over the changes between this dictionary and the previous version. */
jens@0:         virtual ChangeIterator* iterateChanges() const;
jens@0: 
jens@0:         
jens@0:         // Stuff you probably won't need to use:
jens@0:         
jens@0:         File* file() const                                          {return _file;}
jens@0:         explicit VersionDictionary (File*);
jens@0:         VersionDictionary (File *file, FilePosition trailerPosition);
jens@0:         
jens@0:     private:
jens@0:         /** The type of the trailer chunk that's used as the position of the dictionary. */
jens@0:         static const uint16_t kChunkType = 3;
jens@0:         
jens@0:         struct IndexPositions {
jens@0:             LittleEndian<FilePosition> position[256];
jens@0:             LittleEndian<FilePosition>& operator[] (int i)              {return position[i];}
jens@0:             LittleEndian<FilePosition> const& operator[] (int i) const  {return position[i];}
jens@0:         };
jens@0:                 
jens@0:         class Trailer;
jens@0:         const Trailer* _trailer() const;
jens@0:         const Index* _index (int i) const;
jens@0:         void _read (FilePosition trailerPosition =0);
jens@0:         static FilePosition _append (const VersionDictionary *baseDict, 
jens@0:                                      const Dictionary *addDict, 
jens@0:                                      File *dstFile, 
jens@0:                                      bool replace);
jens@0:         
jens@0:         File *_file;
jens@0:         FilePosition _trailerPosition, _previousTrailerPosition;
jens@0:         IndexPositions _indexPositions;
jens@0:         int _count;
jens@0:         mutable const VersionDictionary *_previousVersion;
jens@0:         
jens@0: #if VERSIONDICTIONARY_TESTING
jens@0:     public:
jens@0: #endif
jens@0:         static VersionDictionary* create (File *file, const Dictionary *srcDict);
jens@0:         VersionDictionary* byAppending (const Dictionary* d) const     {return _appendAndOpen(d,_file,false);}
jens@0:         VersionDictionary* byReplacing (const Dictionary* d) const     {return _appendAndOpen(d,_file,true);}
jens@0:         VersionDictionary* _appendAndOpen (const Dictionary *addDict, File *dstFile, bool replace) const;
jens@0:         
jens@0:         friend class Ottoman;
jens@0:         UNCOPYABLE(VersionDictionary);
jens@0:     };
jens@0:     
jens@0:     
jens@0:     class VersionDictionary::Iterator :public Dictionary::Iterator {
jens@0:     public:
jens@0:         explicit Iterator (const VersionDictionary*);
jens@0:         virtual ~Iterator();
jens@0:         virtual Key key() const;
jens@0:         virtual Blob value() const;
jens@0:         virtual bool next();
jens@0:         virtual bool hasValue() const;
jens@0:     private:
jens@0:         bool nextIndex();
jens@0:         
jens@0:         const VersionDictionary *_file;
jens@0:         int _bucket;
jens@0:         Dictionary::Iterator *_iter;
jens@0:         UNCOPYABLE(Iterator);
jens@0:     };
jens@0:     
jens@0:     
jens@0:     class VersionDictionary::ChangeIterator :public Dictionary::Iterator {
jens@0:     public:
jens@0:         explicit ChangeIterator (const VersionDictionary*);
jens@0:         virtual ~ChangeIterator();
jens@0:         virtual Key key() const;
jens@0:         virtual Blob value() const;
jens@0:         virtual bool next();
jens@0:         virtual bool hasValue() const;
jens@0:     private:
jens@0:         bool nextIndex();
jens@0:         
jens@0:         const VersionDictionary *_file;
jens@0:         int _bucket;
jens@0:         Dictionary::Iterator *_iter;
jens@0:         UNCOPYABLE(ChangeIterator);
jens@0:     };
jens@0: 
jens@0: }
jens@0: 
jens@0: #endif //_MOOSEYARD_VERSIONDICTIONARY_