/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*

 * The storage stream provides an internal buffer that can be filled by a

 * client using a single output stream.  One or more independent input streams

 * can be created to read the data out non-destructively.  The implementation

 * uses a segmented buffer internally to avoid realloc'ing of large buffers,

 * with the attendant performance loss and heap fragmentation.

 */

#ifndef _nsStorageStream_h_

#define _nsStorageStream_h_

#include "nsIStorageStream.h"

#include "nsIOutputStream.h"

#include "nsMemory.h"

#include "mozilla/Attributes.h"

#define NS_STORAGESTREAM_CID                       \

{ /* 669a9795-6ff7-4ed4-9150-c34ce2971b63 */       \

  0x669a9795,                                      \

  0x6ff7,                                          \

  0x4ed4,                                          \

  {0x91, 0x50, 0xc3, 0x4c, 0xe2, 0x97, 0x1b, 0x63} \

}

#define NS_STORAGESTREAM_CONTRACTID "@mozilla.org/storagestream;1"

class nsSegmentedBuffer;

class nsStorageStream final

  : public nsIStorageStream

  , public nsIOutputStream

{

public:

  nsStorageStream();

  NS_DECL_THREADSAFE_ISUPPORTS

  NS_DECL_NSISTORAGESTREAM

  NS_DECL_NSIOUTPUTSTREAM

  friend class nsStorageInputStream;

private:

  ~nsStorageStream();

  nsSegmentedBuffer* mSegmentedBuffer;

  uint32_t           mSegmentSize;       // All segments, except possibly the last, are of this size

                                         //   Must be power-of-2

  uint32_t           mSegmentSizeLog2;   // log2(mSegmentSize)

  bool               mWriteInProgress;   // true, if an un-Close'ed output stream exists

  int32_t            mLastSegmentNum;    // Last segment # in use, -1 initially

  char*              mWriteCursor;       // Pointer to next byte to be written

  char*              mSegmentEnd;        // Pointer to one byte after end of segment

                                         //   containing the write cursor

  uint32_t           mLogicalLength;     // Number of bytes written to stream

  nsresult Seek(int32_t aPosition);

  uint32_t SegNum(uint32_t aPosition)

  {

    return aPosition >> mSegmentSizeLog2;

  }

  uint32_t SegOffset(uint32_t aPosition)

  {

    return aPosition & (mSegmentSize - 1);

  }

};

#endif //  _nsStorageStream_h_