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       1             : /* -*-  Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : #ifndef mozilla_devtools_ZeroCopyNSIOutputStream__
       7             : #define mozilla_devtools_ZeroCopyNSIOutputStream__
       8             : 
       9             : #include <google/protobuf/io/zero_copy_stream.h>
      10             : #include <google/protobuf/stubs/common.h>
      11             : 
      12             : #include "nsCOMPtr.h"
      13             : #include "nsIOutputStream.h"
      14             : 
      15             : namespace mozilla {
      16             : namespace devtools {
      17             : 
      18             : // A `google::protobuf::io::ZeroCopyOutputStream` implementation that uses an
      19             : // `nsIOutputStream` under the covers.
      20             : //
      21             : // This class will automatically write and flush its data to the
      22             : // `nsIOutputStream` in its destructor, but if you care whether that call
      23             : // succeeds or fails, then you should call the `flush` method yourself. Errors
      24             : // will be logged, however.
      25             : class MOZ_STACK_CLASS ZeroCopyNSIOutputStream
      26             :   : public ::google::protobuf::io::ZeroCopyOutputStream
      27             : {
      28             :   static const int BUFFER_SIZE = 8192;
      29             : 
      30             :   // The nsIOutputStream we are streaming to.
      31             :   nsCOMPtr<nsIOutputStream>& out;
      32             : 
      33             :   // The buffer we write data to before passing it to the output stream.
      34             :   char buffer[BUFFER_SIZE];
      35             : 
      36             :   // The status of writing to the underlying output stream.
      37             :   nsresult result_;
      38             : 
      39             :   // The number of bytes in the buffer that have been used thus far.
      40             :   int amountUsed;
      41             : 
      42             :   // Excluding the amount of the buffer currently used (which hasn't been
      43             :   // written and flushed yet), this is the number of bytes written to the output
      44             :   // stream.
      45             :   int64_t writtenCount;
      46             : 
      47             :   // Write the internal buffer to the output stream and flush it.
      48             :   nsresult writeBuffer();
      49             : 
      50             : public:
      51             :   explicit ZeroCopyNSIOutputStream(nsCOMPtr<nsIOutputStream>& out);
      52             : 
      53             :   nsresult flush() { return writeBuffer(); }
      54             : 
      55             :   // Return true if writing to the underlying output stream ever failed.
      56           0 :   bool failed() const { return NS_FAILED(result_); }
      57             : 
      58           0 :   nsresult result() const { return result_; }
      59             : 
      60             :   // ZeroCopyOutputStream Interface
      61             :   virtual ~ZeroCopyNSIOutputStream() override;
      62             :   virtual bool Next(void** data, int* size) override;
      63             :   virtual void BackUp(int count) override;
      64             :   virtual ::google::protobuf::int64 ByteCount() const override;
      65             : };
      66             : 
      67             : } // namespace devtools
      68             : } // namespace mozilla
      69             : 
      70             : #endif // mozilla_devtools_ZeroCopyNSIOutputStream__