gecko-dev/netwerk/base/nsBufferedStreams.h

/* -*- 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 nsBufferedStreams_h__
#define nsBufferedStreams_h__

#include "nsIBufferedStreams.h"
#include "nsIInputStream.h"
#include "nsIOutputStream.h"
#include "nsISafeOutputStream.h"
#include "nsISeekableStream.h"
#include "nsIStreamBufferAccess.h"
#include "nsCOMPtr.h"
#include "nsIIPCSerializableInputStream.h"
#include "nsIAsyncInputStream.h"
#include "nsICloneableInputStream.h"
#include "nsIInputStreamLength.h"
#include "mozilla/Mutex.h"
#include "mozilla/RecursiveMutex.h"

////////////////////////////////////////////////////////////////////////////////

class nsBufferedStream : public nsISeekableStream {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSISEEKABLESTREAM
  NS_DECL_NSITELLABLESTREAM

  nsBufferedStream() = default;

  void Close();

 protected:
  virtual ~nsBufferedStream();

  nsresult Init(nsISupports* stream, uint32_t bufferSize);
  nsresult GetData(nsISupports** aResult);
  NS_IMETHOD Fill() = 0;
  NS_IMETHOD Flush() = 0;

  uint32_t mBufferSize{0};
  char* mBuffer MOZ_GUARDED_BY(mBufferMutex){nullptr};

  mozilla::RecursiveMutex mBufferMutex{"nsBufferedStream::mBufferMutex"};

  // mBufferStartOffset is the offset relative to the start of mStream.
  int64_t mBufferStartOffset{0};

  // mCursor is the read cursor for input streams, or write cursor for
  // output streams, and is relative to mBufferStartOffset.
  uint32_t mCursor{0};

  // mFillPoint is the amount available in the buffer for input streams,
  // or the high watermark of bytes written into the buffer, and therefore
  // is relative to mBufferStartOffset.
  uint32_t mFillPoint{0};

  nsCOMPtr<nsISupports> mStream;  // cast to appropriate subclass

  bool mBufferDisabled{false};
  bool mEOF{false};  // True if mStream is at EOF
  bool mSeekable{true};
  uint8_t mGetBufferCount{0};
};

////////////////////////////////////////////////////////////////////////////////

class nsBufferedInputStream final : public nsBufferedStream,
                                    public nsIBufferedInputStream,
                                    public nsIStreamBufferAccess,
                                    public nsIIPCSerializableInputStream,
                                    public nsIAsyncInputStream,
                                    public nsIInputStreamCallback,
                                    public nsICloneableInputStream,
                                    public nsIInputStreamLength,
                                    public nsIAsyncInputStreamLength,
                                    public nsIInputStreamLengthCallback {
 public:
  NS_DECL_ISUPPORTS_INHERITED
  NS_DECL_NSIINPUTSTREAM
  NS_DECL_NSIBUFFEREDINPUTSTREAM
  NS_DECL_NSISTREAMBUFFERACCESS
  NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
  NS_DECL_NSIASYNCINPUTSTREAM
  NS_DECL_NSIINPUTSTREAMCALLBACK
  NS_DECL_NSICLONEABLEINPUTSTREAM
  NS_DECL_NSIINPUTSTREAMLENGTH
  NS_DECL_NSIASYNCINPUTSTREAMLENGTH
  NS_DECL_NSIINPUTSTREAMLENGTHCALLBACK

  nsBufferedInputStream() = default;

  static nsresult Create(REFNSIID aIID, void** aResult);

  nsIInputStream* Source() { return (nsIInputStream*)mStream.get(); }

  /**
   * If there's a reference/pointer to an nsBufferedInputStream BEFORE calling
   * Init() AND the intent is to ultimately convert/assign that
   * reference/pointer to an nsIInputStream, DO NOT use that initial
   * reference/pointer. Instead, use the value of QueryInterface-ing to an
   * nsIInputStream (and, again, the QueryInterface must be performed after
   * Init()). This is because nsBufferedInputStream has multiple underlying
   * nsIInputStreams (one from nsIBufferedInputStream and one from
   * nsIAsyncInputStream), and the correct base nsIInputStream to use will be
   * unknown until the final value of mIsAsyncInputStream is set in Init().
   *
   * This method, however, does just that but also hides the QI details and
   * will assert if called before Init().
   */
  already_AddRefed<nsIInputStream> GetInputStream();

 protected:
  virtual ~nsBufferedInputStream() = default;

  NS_IMETHOD Fill() override;
  NS_IMETHOD Flush() override { return NS_OK; }  // no-op for input streams

  mozilla::Mutex mMutex MOZ_UNANNOTATED{"nsBufferedInputStream::mMutex"};

  // This value is protected by mutex.
  nsCOMPtr<nsIInputStreamCallback> mAsyncWaitCallback;

  // This value is protected by mutex.
  nsCOMPtr<nsIInputStreamLengthCallback> mAsyncInputStreamLengthCallback;

  bool mIsIPCSerializable{true};
  bool mIsAsyncInputStream{false};
  bool mIsCloneableInputStream{false};
  bool mIsInputStreamLength{false};
  bool mIsAsyncInputStreamLength{false};
};

////////////////////////////////////////////////////////////////////////////////

class nsBufferedOutputStream : public nsBufferedStream,
                               public nsISafeOutputStream,
                               public nsIBufferedOutputStream,
                               public nsIStreamBufferAccess {
 public:
  NS_DECL_ISUPPORTS_INHERITED
  NS_DECL_NSIOUTPUTSTREAM
  NS_DECL_NSISAFEOUTPUTSTREAM
  NS_DECL_NSIBUFFEREDOUTPUTSTREAM
  NS_DECL_NSISTREAMBUFFERACCESS

  nsBufferedOutputStream() = default;

  static nsresult Create(REFNSIID aIID, void** aResult);

  nsIOutputStream* Sink() { return (nsIOutputStream*)mStream.get(); }

 protected:
  virtual ~nsBufferedOutputStream() { nsBufferedOutputStream::Close(); }

  NS_IMETHOD Fill() override { return NS_OK; }  // no-op for output streams

  nsCOMPtr<nsISafeOutputStream> mSafeStream;  // QI'd from mStream
};

////////////////////////////////////////////////////////////////////////////////

#endif  // nsBufferedStreams_h__