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70 lines
2.3 KiB
C++
70 lines
2.3 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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#ifndef mozilla_SnappyCompressOutputStream_h__
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#define mozilla_SnappyCompressOutputStream_h__
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#include "mozilla/Attributes.h"
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#include "mozilla/UniquePtr.h"
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#include "nsCOMPtr.h"
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#include "nsIOutputStream.h"
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#include "nsISupportsImpl.h"
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#include "SnappyFrameUtils.h"
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namespace mozilla {
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class SnappyCompressOutputStream MOZ_FINAL : public nsIOutputStream
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, protected detail::SnappyFrameUtils
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{
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public:
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// Maximum compression block size.
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static const size_t kMaxBlockSize;
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// Construct a new blocking output stream to compress data to
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// the given base stream. The base stream must also be blocking.
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// The compression block size may optionally be set to a value
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// up to kMaxBlockSize.
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explicit SnappyCompressOutputStream(nsIOutputStream* aBaseStream,
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size_t aBlockSize = kMaxBlockSize);
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// The compression block size. To optimize stream performance
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// try to write to the stream in segments at least this size.
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size_t BlockSize() const;
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private:
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virtual ~SnappyCompressOutputStream();
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nsresult FlushToBaseStream();
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nsresult MaybeFlushStreamIdentifier();
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nsresult WriteAll(const char* aBuf, uint32_t aCount,
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uint32_t* aBytesWrittenOut);
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nsCOMPtr<nsIOutputStream> mBaseStream;
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const size_t mBlockSize;
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// Buffer holding copied uncompressed data. This must be copied here
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// so that the compression can be performed on a single flat buffer.
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mozilla::UniquePtr<char[]> mBuffer;
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// The next byte in the uncompressed data to copy incoming data to.
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size_t mNextByte;
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// Buffer holding the resulting compressed data.
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mozilla::UniquePtr<char[]> mCompressedBuffer;
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size_t mCompressedBufferLength;
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// The first thing written to the stream must be a stream identifier.
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bool mStreamIdentifierWritten;
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public:
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSIOUTPUTSTREAM
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};
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} // namespace mozilla
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#endif // mozilla_SnappyCompressOutputStream_h__
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