mojo/edk/system/local_data_pipe_impl.h

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MOJO_EDK_SYSTEM_LOCAL_DATA_PIPE_IMPL_H_
#define MOJO_EDK_SYSTEM_LOCAL_DATA_PIPE_IMPL_H_

#include "base/memory/aligned_memory.h"
#include "base/memory/scoped_ptr.h"
#include "mojo/edk/system/data_pipe_impl.h"
#include "mojo/edk/system/system_impl_export.h"
#include "mojo/public/cpp/system/macros.h"

namespace mojo {
namespace system {

class MessageInTransitQueue;

// |LocalDataPipeImpl| is a subclass that "implements" |DataPipe| for data pipes
// whose producer and consumer are both local. See |DataPipeImpl| for more
// details.
class MOJO_SYSTEM_IMPL_EXPORT LocalDataPipeImpl final : public DataPipeImpl {
 public:
  LocalDataPipeImpl();
  ~LocalDataPipeImpl() override;

 private:
  // |DataPipeImpl| implementation:
  void ProducerClose() override;
  MojoResult ProducerWriteData(UserPointer<const void> elements,
                               UserPointer<uint32_t> num_bytes,
                               uint32_t max_num_bytes_to_write,
                               uint32_t min_num_bytes_to_write) override;
  MojoResult ProducerBeginWriteData(UserPointer<void*> buffer,
                                    UserPointer<uint32_t> buffer_num_bytes,
                                    uint32_t min_num_bytes_to_write) override;
  MojoResult ProducerEndWriteData(uint32_t num_bytes_written) override;
  HandleSignalsState ProducerGetHandleSignalsState() const override;
  void ProducerStartSerialize(Channel* channel,
                              size_t* max_size,
                              size_t* max_platform_handles) override;
  bool ProducerEndSerialize(
      Channel* channel,
      void* destination,
      size_t* actual_size,
      embedder::PlatformHandleVector* platform_handles) override;
  void ConsumerClose() override;
  MojoResult ConsumerReadData(UserPointer<void> elements,
                              UserPointer<uint32_t> num_bytes,
                              uint32_t max_num_bytes_to_read,
                              uint32_t min_num_bytes_to_read,
                              bool peek) override;
  MojoResult ConsumerDiscardData(UserPointer<uint32_t> num_bytes,
                                 uint32_t max_num_bytes_to_discard,
                                 uint32_t min_num_bytes_to_discard) override;
  MojoResult ConsumerQueryData(UserPointer<uint32_t> num_bytes) override;
  MojoResult ConsumerBeginReadData(UserPointer<const void*> buffer,
                                   UserPointer<uint32_t> buffer_num_bytes,
                                   uint32_t min_num_bytes_to_read) override;
  MojoResult ConsumerEndReadData(uint32_t num_bytes_read) override;
  HandleSignalsState ConsumerGetHandleSignalsState() const override;
  void ConsumerStartSerialize(Channel* channel,
                              size_t* max_size,
                              size_t* max_platform_handles) override;
  bool ConsumerEndSerialize(
      Channel* channel,
      void* destination,
      size_t* actual_size,
      embedder::PlatformHandleVector* platform_handles) override;
  bool OnReadMessage(unsigned port, MessageInTransit* message) override;
  void OnDetachFromChannel(unsigned port) override;

  void EnsureBuffer();
  void DestroyBuffer();

  // Get the maximum (single) write/read size right now (in number of elements);
  // result fits in a |uint32_t|.
  size_t GetMaxNumBytesToWrite();
  size_t GetMaxNumBytesToRead();

  // Marks the given number of bytes as consumed/discarded. |num_bytes| must be
  // no greater than |current_num_bytes_|.
  void MarkDataAsConsumed(size_t num_bytes);

  scoped_ptr<char, base::AlignedFreeDeleter> buffer_;
  // Circular buffer.
  size_t start_index_;
  size_t current_num_bytes_;

  MOJO_DISALLOW_COPY_AND_ASSIGN(LocalDataPipeImpl);
};

}  // namespace system
}  // namespace mojo

#endif  // MOJO_EDK_SYSTEM_LOCAL_DATA_PIPE_IMPL_H_