netfilecache.h

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#pragma once

/*+
________________________________________________________________________

 (C) dGB Beheer B.V.; (LICENSE) http://opendtect.org/OpendTect_license.txt
 Author:        Bert
 Date:          April 2016
________________________________________________________________________

-*/

#include "networkmod.h"
#include "ranges.h"
#include "sets.h"
#include "od_iosfwd.h"


namespace Network
{

mExpClass(Network) FileCache
{
public:

    typedef unsigned char               BufType;
    typedef int                         ChunkSizeType;
    typedef od_stream_Count             FileSizeType;
    typedef od_stream_Pos               FilePosType;
    typedef Interval<FilePosType>       FileChunkType;
    typedef TypeSet<FileChunkType>      FileChunkSetType;

    virtual             ~FileCache();

    FileSizeType        size() const;
    bool                isEmpty() const                 { return size() < 1; }
    virtual void        clearData()                     = 0;

    virtual void        setMinCacheSize(FileSizeType)   = 0;

protected:

                        FileCache(FileSizeType);

    class Block
    {
    public:

        typedef ChunkSizeType   SizeType;
        typedef SizeType        PosType;
        static const SizeType   cFullSize;

                        Block(PosType);
                        ~Block();

        BufType*        buf_;
        SizeType        bufsz_;

    };

public:

    // Block-based access

    typedef ObjectSet<Block>::size_type BlockIdxType;
    typedef Block::SizeType             BlockSizeType;

    BlockIdxType        blockIdx(FilePosType) const;
    static FilePosType  blockStart(BlockIdxType);
    BlockSizeType       blockSize(BlockIdxType) const;
    inline bool         validBlockIdx( BlockIdxType bidx ) const
                        { return blocks_.validIdx(bidx); }

    bool                isLiveBlock(BlockIdxType) const;
    BufType*            getBlock(BlockIdxType);
    const BufType*      getBlock(BlockIdxType) const;

protected:

    ObjectSet<Block>    blocks_;
    const BlockSizeType lastblocksz_;
    const FileSizeType  knownfilesize_;

    Block*              gtBlk(BlockIdxType) const;
    void                dismissBlock(BlockIdxType);
    void                clearBlocks();
    inline FilePosType  lastBlockPos() const
                        { return blockStart(blocks_.size()-1); }
    inline FilePosType  lastFilePos() const
                        { return lastBlockPos() + lastblocksz_ - 1; }

    virtual void        handleNewLiveBlock(BlockIdxType)        {}

};


mExpClass(Network) ReadCache : public FileCache
{
public:

                        ReadCache(FileSizeType knownsize=0);
                        ~ReadCache();

    virtual void        clearData();
    virtual void        setMinCacheSize(FileSizeType);

                        // Free-sized access of buffered data
    bool                isAvailable(FilePosType,FileSizeType) const;
    FileSizeType        getAt(FilePosType,BufType*,FileSizeType) const;
                        // returns actual nr bytes handled

                        // Stuff data, presumably obtained from remote source
    FileChunkSetType    stillNeededDataFor(FilePosType,ChunkSizeType) const;
    bool                setData(FileChunkType,const BufType*);

protected:

    TypeSet<BlockIdxType> liveblockidxs_;
    BlockIdxType        maxnrliveblocks_;

    virtual void        handleNewLiveBlock(BlockIdxType);

};


mExpClass(Network) WriteCache : public FileCache
{
public:

                        WriteCache();
                        ~WriteCache();

    virtual void        clearData();
    virtual void        setMinCacheSize(FileSizeType);


protected:

    BlockIdxType        nrblocksmem_;

    virtual void        handleNewLiveBlock(BlockIdxType);

};

} // namespace Network