зеркало из https://github.com/mozilla/gecko-dev.git
74 строки
2.5 KiB
C++
74 строки
2.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* The storage stream provides an internal buffer that can be filled by a
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* client using a single output stream. One or more independent input streams
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* can be created to read the data out non-destructively. The implementation
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* uses a segmented buffer internally to avoid realloc'ing of large buffers,
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* with the attendant performance loss and heap fragmentation.
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*/
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#ifndef _nsStorageStream_h_
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#define _nsStorageStream_h_
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#include "nsIStorageStream.h"
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#include "nsIOutputStream.h"
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#include "nsMemory.h"
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#include "mozilla/Attributes.h"
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#define NS_STORAGESTREAM_CID \
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{ /* 669a9795-6ff7-4ed4-9150-c34ce2971b63 */ \
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0x669a9795, \
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0x6ff7, \
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0x4ed4, \
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{0x91, 0x50, 0xc3, 0x4c, 0xe2, 0x97, 0x1b, 0x63} \
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}
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#define NS_STORAGESTREAM_CONTRACTID "@mozilla.org/storagestream;1"
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class nsSegmentedBuffer;
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class nsStorageStream final
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: public nsIStorageStream
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, public nsIOutputStream
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{
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public:
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nsStorageStream();
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSISTORAGESTREAM
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NS_DECL_NSIOUTPUTSTREAM
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friend class nsStorageInputStream;
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private:
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~nsStorageStream();
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nsSegmentedBuffer* mSegmentedBuffer;
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uint32_t mSegmentSize; // All segments, except possibly the last, are of this size
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// Must be power-of-2
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uint32_t mSegmentSizeLog2; // log2(mSegmentSize)
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bool mWriteInProgress; // true, if an un-Close'ed output stream exists
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int32_t mLastSegmentNum; // Last segment # in use, -1 initially
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char* mWriteCursor; // Pointer to next byte to be written
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char* mSegmentEnd; // Pointer to one byte after end of segment
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// containing the write cursor
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uint32_t mLogicalLength; // Number of bytes written to stream
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NS_METHOD Seek(int32_t aPosition);
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uint32_t SegNum(uint32_t aPosition)
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{
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return aPosition >> mSegmentSizeLog2;
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}
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uint32_t SegOffset(uint32_t aPosition)
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{
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return aPosition & (mSegmentSize - 1);
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}
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};
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#endif // _nsStorageStream_h_
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