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