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72 lines
2.8 KiB
C++
72 lines
2.8 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* The contents of this file are subject to the Netscape Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is Mozilla Communicator client code, released
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* March 31, 1998.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998-1999 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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*/
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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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class nsSegmentedBuffer;
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class NS_COM nsStorageStream : 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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virtual ~nsStorageStream();
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NS_METHOD Init(PRUint32 segmentSize, PRUint32 maxSize, nsIMemory *segmentAllocator = 0);
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NS_DECL_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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nsSegmentedBuffer* mSegmentedBuffer;
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PRUint32 mSegmentSize; // All segments, except possibly the last, are of this size
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// Must be power-of-2
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PRUint32 mSegmentSizeLog2; // log2(mSegmentSize)
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PRBool mWriteInProgress; // true, if an un-Close'ed output stream exists
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PRInt32 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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PRUint32 mLogicalLength; // Number of bytes written to stream
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NS_METHOD Seek(PRInt32 aPosition);
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PRUint32 SegNum(PRUint32 aPosition) {return aPosition >> mSegmentSizeLog2;}
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PRUint32 SegOffset(PRUint32 aPosition) {return aPosition & (mSegmentSize - 1);}
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};
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#endif // _nsStorageStream_h_
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