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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_SnappyCompressOutputStream_h__
#define mozilla_SnappyCompressOutputStream_h__
#include "mozilla/Attributes.h"
#include "mozilla/UniquePtr.h"
#include "nsCOMPtr.h"
#include "nsIOutputStream.h"
#include "nsISupportsImpl.h"
#include "SnappyFrameUtils.h"
namespace mozilla {
class SnappyCompressOutputStream final : public nsIOutputStream
, protected detail::SnappyFrameUtils
{
public:
// Maximum compression block size.
static const size_t kMaxBlockSize;
// Construct a new blocking output stream to compress data to
// the given base stream. The base stream must also be blocking.
// The compression block size may optionally be set to a value
// up to kMaxBlockSize.
explicit SnappyCompressOutputStream(nsIOutputStream* aBaseStream,
size_t aBlockSize = kMaxBlockSize);
// The compression block size. To optimize stream performance
// try to write to the stream in segments at least this size.
size_t BlockSize() const;
private:
virtual ~SnappyCompressOutputStream();
nsresult FlushToBaseStream();
nsresult MaybeFlushStreamIdentifier();
nsresult WriteAll(const char* aBuf, uint32_t aCount,
uint32_t* aBytesWrittenOut);
nsCOMPtr<nsIOutputStream> mBaseStream;
const size_t mBlockSize;
// Buffer holding copied uncompressed data. This must be copied here
// so that the compression can be performed on a single flat buffer.
mozilla::UniquePtr<char[]> mBuffer;
// The next byte in the uncompressed data to copy incoming data to.
size_t mNextByte;
// Buffer holding the resulting compressed data.
mozilla::UniquePtr<char[]> mCompressedBuffer;
size_t mCompressedBufferLength;
// The first thing written to the stream must be a stream identifier.
bool mStreamIdentifierWritten;
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIOUTPUTSTREAM
};
} // namespace mozilla
#endif // mozilla_SnappyCompressOutputStream_h__
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