dom/quota/MemoryOutputStream.h
author Brian Hackett <bhackett1024@gmail.com>
Fri, 31 Aug 2018 05:35:36 -1000
changeset 434430 d8447a4c32e7d4d991773f478f9dd2996628c51c
parent 432345 3ef89713c643aea9bda9f69a60a1b76995c762ae
child 448947 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1486616 - Execute record/replay triggers when finalizing deferred things, r=mccr8.

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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_dom_quota_MemoryOutputStream_h
#define mozilla_dom_quota_MemoryOutputStream_h

#include "nsIOutputStream.h"

namespace mozilla {
namespace dom {
namespace quota {

// An output stream so you can read your potentially-async input stream into
// a contiguous buffer in the form of an nsCString using NS_AsyncCopy.
// Back when streams were more synchronous and people didn't know blocking I/O
// was bad, if you wanted to read a stream into a flat buffer, you could use
// NS_ReadInputStreamToString/NS_ReadInputStreamToBuffer.  But those don't work
// with async streams. This can be used to replace hand-rolled Read/AsyncWait()
// loops.  Because you specify the expected size up front, the nsCString buffer
// is pre-allocated so wasteful reallocations can be avoided.  However,
// nsCString currently may over-allocate and this can be problematic on 32-bit
// windows until we're rid of that build configuration.
class MemoryOutputStream final
  : public nsIOutputStream
{
  nsCString mData;
  uint64_t mOffset;

public:
  static already_AddRefed<MemoryOutputStream>
  Create(uint64_t aSize);

  const nsCString&
  Data() const
  {
    return mData;
  }

private:
  MemoryOutputStream()
  : mOffset(0)
  { }

  virtual ~MemoryOutputStream()
  { }

  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIOUTPUTSTREAM
};

} // namespace quota
} // namespace dom
} // namespace mozilla

#endif /* mozilla_dom_quota_MemoryOutputStream_h */