1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/io/nsStorageStream.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,65 @@
1.4 +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
1.5 + * This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/*
1.10 + * The storage stream provides an internal buffer that can be filled by a
1.11 + * client using a single output stream. One or more independent input streams
1.12 + * can be created to read the data out non-destructively. The implementation
1.13 + * uses a segmented buffer internally to avoid realloc'ing of large buffers,
1.14 + * with the attendant performance loss and heap fragmentation.
1.15 + */
1.16 +
1.17 +#ifndef _nsStorageStream_h_
1.18 +#define _nsStorageStream_h_
1.19 +
1.20 +#include "nsIStorageStream.h"
1.21 +#include "nsIOutputStream.h"
1.22 +#include "nsMemory.h"
1.23 +#include "mozilla/Attributes.h"
1.24 +
1.25 +#define NS_STORAGESTREAM_CID \
1.26 +{ /* 669a9795-6ff7-4ed4-9150-c34ce2971b63 */ \
1.27 + 0x669a9795, \
1.28 + 0x6ff7, \
1.29 + 0x4ed4, \
1.30 + {0x91, 0x50, 0xc3, 0x4c, 0xe2, 0x97, 0x1b, 0x63} \
1.31 +}
1.32 +
1.33 +#define NS_STORAGESTREAM_CONTRACTID "@mozilla.org/storagestream;1"
1.34 +
1.35 +class nsSegmentedBuffer;
1.36 +
1.37 +class nsStorageStream MOZ_FINAL : public nsIStorageStream,
1.38 + public nsIOutputStream
1.39 +{
1.40 +public:
1.41 + nsStorageStream();
1.42 +
1.43 + NS_DECL_THREADSAFE_ISUPPORTS
1.44 + NS_DECL_NSISTORAGESTREAM
1.45 + NS_DECL_NSIOUTPUTSTREAM
1.46 +
1.47 + friend class nsStorageInputStream;
1.48 +
1.49 +private:
1.50 + ~nsStorageStream();
1.51 +
1.52 + nsSegmentedBuffer* mSegmentedBuffer;
1.53 + uint32_t mSegmentSize; // All segments, except possibly the last, are of this size
1.54 + // Must be power-of-2
1.55 + uint32_t mSegmentSizeLog2; // log2(mSegmentSize)
1.56 + bool mWriteInProgress; // true, if an un-Close'ed output stream exists
1.57 + int32_t mLastSegmentNum; // Last segment # in use, -1 initially
1.58 + char* mWriteCursor; // Pointer to next byte to be written
1.59 + char* mSegmentEnd; // Pointer to one byte after end of segment
1.60 + // containing the write cursor
1.61 + uint32_t mLogicalLength; // Number of bytes written to stream
1.62 +
1.63 + NS_METHOD Seek(int32_t aPosition);
1.64 + uint32_t SegNum(uint32_t aPosition) {return aPosition >> mSegmentSizeLog2;}
1.65 + uint32_t SegOffset(uint32_t aPosition) {return aPosition & (mSegmentSize - 1);}
1.66 +};
1.67 +
1.68 +#endif // _nsStorageStream_h_
