74 lines
2.5 KiB
C++
74 lines
2.5 KiB
C++
/* -*- 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
|
|
|
|
NS_METHOD 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_
|