gecko-dev/toolkit/devtools/heapsnapshot/ZeroCopyNSIOutputStream.h

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/* -*- Mode: C++; tab-width: 2; 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_devtools_ZeroCopyNSIOutputStream__
#define mozilla_devtools_ZeroCopyNSIOutputStream__
#include <google/protobuf/io/zero_copy_stream.h>
#include <google/protobuf/stubs/common.h>
#include "nsCOMPtr.h"
#include "nsIOutputStream.h"
namespace mozilla {
namespace devtools {
// A `google::protobuf::io::ZeroCopyOutputStream` implementation that uses an
// `nsIOutputStream` under the covers.
//
// This class will automatically write and flush its data to the
// `nsIOutputStream` in its destructor, but if you care whether that call
// succeeds or fails, then you should call the `flush` method yourself. Errors
// will be logged, however.
class MOZ_STACK_CLASS ZeroCopyNSIOutputStream
: public ::google::protobuf::io::ZeroCopyOutputStream
{
static const int BUFFER_SIZE = 8192;
// The nsIOutputStream we are streaming to.
nsCOMPtr<nsIOutputStream>& out;
// The buffer we write data to before passing it to the output stream.
char buffer[BUFFER_SIZE];
// The status of writing to the underlying output stream.
nsresult result_;
// The number of bytes in the buffer that have been used thus far.
int amountUsed;
// Excluding the amount of the buffer currently used (which hasn't been
// written and flushed yet), this is the number of bytes written to the output
// stream.
int64_t writtenCount;
// Write the internal buffer to the output stream and flush it.
nsresult writeBuffer();
public:
explicit ZeroCopyNSIOutputStream(nsCOMPtr<nsIOutputStream>& out);
nsresult flush() { return writeBuffer(); }
// Return true if writing to the underlying output stream ever failed.
bool failed() const { return NS_FAILED(result_); }
nsresult result() const { return result_; }
// ZeroCopyOutputStream Interface
virtual ~ZeroCopyNSIOutputStream() override;
virtual bool Next(void** data, int* size) override;
virtual void BackUp(int count) override;
virtual ::google::protobuf::int64 ByteCount() const override;
};
} // namespace devtools
} // namespace mozilla
#endif // mozilla_devtools_ZeroCopyNSIOutputStream__