devtools/shared/heapsnapshot/ZeroCopyNSIOutputStream.cpp
author Sylvestre Ledru <sledru@mozilla.com>
Fri, 30 Nov 2018 11:46:48 +0100
changeset 448947 6f3709b3878117466168c40affa7bca0b60cf75b
parent 448216 fb09acfff1684500e989acc798e97fa7f9358dc0
permissions -rw-r--r--
Bug 1511181 - Reformat everything to the Google coding style r=ehsan a=clang-format # ignore-this-changeset

/* -*- 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/. */

#include "mozilla/devtools/ZeroCopyNSIOutputStream.h"

#include "mozilla/DebugOnly.h"
#include "mozilla/Unused.h"

namespace mozilla {
namespace devtools {

ZeroCopyNSIOutputStream::ZeroCopyNSIOutputStream(nsCOMPtr<nsIOutputStream>& out)
    : out(out), result_(NS_OK), amountUsed(0), writtenCount(0) {
  DebugOnly<bool> nonBlocking = false;
  MOZ_ASSERT(out->IsNonBlocking(&nonBlocking) == NS_OK);
  MOZ_ASSERT(!nonBlocking);
}

ZeroCopyNSIOutputStream::~ZeroCopyNSIOutputStream() {
  if (!failed()) Unused << NS_WARN_IF(NS_FAILED(writeBuffer()));
}

nsresult ZeroCopyNSIOutputStream::writeBuffer() {
  if (failed()) return result_;

  if (amountUsed == 0) return NS_OK;

  int32_t amountWritten = 0;
  while (amountWritten < amountUsed) {
    uint32_t justWritten = 0;

    result_ = out->Write(buffer + amountWritten, amountUsed - amountWritten,
                         &justWritten);
    if (NS_WARN_IF(NS_FAILED(result_))) return result_;

    amountWritten += justWritten;
  }

  writtenCount += amountUsed;
  amountUsed = 0;
  return NS_OK;
}

// ZeroCopyOutputStream Interface

bool ZeroCopyNSIOutputStream::Next(void** data, int* size) {
  MOZ_ASSERT(data != nullptr);
  MOZ_ASSERT(size != nullptr);

  if (failed()) return false;

  if (amountUsed == BUFFER_SIZE) {
    if (NS_FAILED(writeBuffer())) return false;
  }

  *data = buffer + amountUsed;
  *size = BUFFER_SIZE - amountUsed;
  amountUsed = BUFFER_SIZE;
  return true;
}

void ZeroCopyNSIOutputStream::BackUp(int count) {
  MOZ_ASSERT(count >= 0, "Cannot back up a negative amount of bytes.");
  MOZ_ASSERT(amountUsed == BUFFER_SIZE,
             "Can only call BackUp directly after calling Next.");
  MOZ_ASSERT(count <= amountUsed,
             "Can't back up further than we've given out.");

  amountUsed -= count;
}

::google::protobuf::int64 ZeroCopyNSIOutputStream::ByteCount() const {
  return writtenCount + amountUsed;
}

}  // namespace devtools
}  // namespace mozilla