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       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : /*
       8             :  * The storage stream provides an internal buffer that can be filled by a
       9             :  * client using a single output stream.  One or more independent input streams
      10             :  * can be created to read the data out non-destructively.  The implementation
      11             :  * uses a segmented buffer internally to avoid realloc'ing of large buffers,
      12             :  * with the attendant performance loss and heap fragmentation.
      13             :  */
      14             : 
      15             : #ifndef _nsStorageStream_h_
      16             : #define _nsStorageStream_h_
      17             : 
      18             : #include "nsIStorageStream.h"
      19             : #include "nsIOutputStream.h"
      20             : #include "nsMemory.h"
      21             : #include "mozilla/Attributes.h"
      22             : 
      23             : #define NS_STORAGESTREAM_CID                       \
      24             : { /* 669a9795-6ff7-4ed4-9150-c34ce2971b63 */       \
      25             :   0x669a9795,                                      \
      26             :   0x6ff7,                                          \
      27             :   0x4ed4,                                          \
      28             :   {0x91, 0x50, 0xc3, 0x4c, 0xe2, 0x97, 0x1b, 0x63} \
      29             : }
      30             : 
      31             : #define NS_STORAGESTREAM_CONTRACTID "@mozilla.org/storagestream;1"
      32             : 
      33             : class nsSegmentedBuffer;
      34             : 
      35             : class nsStorageStream final
      36             :   : public nsIStorageStream
      37             :   , public nsIOutputStream
      38             : {
      39             : public:
      40             :   nsStorageStream();
      41             : 
      42             :   NS_DECL_THREADSAFE_ISUPPORTS
      43             :   NS_DECL_NSISTORAGESTREAM
      44             :   NS_DECL_NSIOUTPUTSTREAM
      45             : 
      46             :   friend class nsStorageInputStream;
      47             : 
      48             : private:
      49             :   ~nsStorageStream();
      50             : 
      51             :   nsSegmentedBuffer* mSegmentedBuffer;
      52             :   uint32_t           mSegmentSize;       // All segments, except possibly the last, are of this size
      53             :                                          //   Must be power-of-2
      54             :   uint32_t           mSegmentSizeLog2;   // log2(mSegmentSize)
      55             :   bool               mWriteInProgress;   // true, if an un-Close'ed output stream exists
      56             :   int32_t            mLastSegmentNum;    // Last segment # in use, -1 initially
      57             :   char*              mWriteCursor;       // Pointer to next byte to be written
      58             :   char*              mSegmentEnd;        // Pointer to one byte after end of segment
      59             :                                          //   containing the write cursor
      60             :   uint32_t           mLogicalLength;     // Number of bytes written to stream
      61             : 
      62             :   nsresult Seek(int32_t aPosition);
      63           0 :   uint32_t SegNum(uint32_t aPosition)
      64             :   {
      65           0 :     return aPosition >> mSegmentSizeLog2;
      66             :   }
      67           0 :   uint32_t SegOffset(uint32_t aPosition)
      68             :   {
      69           0 :     return aPosition & (mSegmentSize - 1);
      70             :   }
      71             : };
      72             : 
      73             : #endif //  _nsStorageStream_h_