/*
 * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

#ifndef SQUID_FS_ROCK_IO_STATE_H
#define SQUID_FS_ROCK_IO_STATE_H

#include "fs/rock/RockSwapDir.h"
#include "MemBlob.h"

class DiskFile;

namespace Rock
{

class DbCellHeader;
class SwapDir;

/// \ingroup Rock
class IoState: public ::StoreIOState
{
public:
    typedef RefCount<IoState> Pointer;

    IoState(Rock::SwapDir::Pointer &aDir, StoreEntry *e, StoreIOState::STFNCB *cbFile, StoreIOState::STIOCB *cbIo, void *data);
    virtual ~IoState();

    void file(const RefCount<DiskFile> &aFile);

    // ::StoreIOState API
    virtual void read_(char *buf, size_t size, off_t offset, STRCB * callback, void *callback_data);
    virtual bool write(char const *buf, size_t size, off_t offset, FREE * free_func);
    virtual void close(int how);

    /// whether we are still waiting for the I/O results (i.e., not closed)
    bool stillWaiting() const { return theFile != NULL; }

    /// forwards read data to the reader that initiated this I/O
    void callReaderBack(const char *buf, int rlen);

    /// called by SwapDir::writeCompleted() after the last write and on error
    void finishedWriting(const int errFlag);

    MEMPROXY_CLASS(IoState);

    /* one and only one of these will be set and locked; access via *Anchor() */
    const Ipc::StoreMapAnchor *readableAnchor_; ///< starting point for reading
    Ipc::StoreMapAnchor *writeableAnchor_; ///< starting point for writing

    SlotId sidCurrent; ///< ID of the db slot currently being read or written

private:
    const Ipc::StoreMapAnchor &readAnchor() const;
    Ipc::StoreMapAnchor &writeAnchor();
    const Ipc::StoreMapSlice &currentReadableSlice() const;

    void tryWrite(char const *buf, size_t size, off_t offset);
    size_t writeToBuffer(char const *buf, size_t size);
    void writeToDisk(const SlotId nextSlot);
    void writeBufToDisk(const SlotId nextSlot, const bool eof);
    SlotId reserveSlotForWriting();

    void callBack(int errflag);

    Rock::SwapDir::Pointer dir; ///< swap dir that initiated I/O
    const size_t slotSize; ///< db cell size
    int64_t objOffset; ///< object offset for current db slot

    RefCount<DiskFile> theFile; // "file" responsible for this I/O
    MemBlob theBuf; // use for write content accumulation only
};

MEMPROXY_CLASS_INLINE(IoState);

} // namespace Rock

#endif /* SQUID_FS_ROCK_IO_STATE_H */