Move mojo edk into mojo/edk

mojo/system/raw_channel.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_SYSTEM_RAW_CHANNEL_H_
-#define MOJO_SYSTEM_RAW_CHANNEL_H_
-
-#include <deque>
-#include <vector>
-
-#include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "base/synchronization/lock.h"
-#include "mojo/embedder/platform_handle_vector.h"
-#include "mojo/embedder/scoped_platform_handle.h"
-#include "mojo/system/constants.h"
-#include "mojo/system/message_in_transit.h"
-#include "mojo/system/system_impl_export.h"
-
-namespace base {
-class MessageLoopForIO;
-}
-
-namespace mojo {
-namespace system {
-
-// |RawChannel| is an interface and base class for objects that wrap an OS
-// "pipe". It presents the following interface to users:
-//  - Receives and dispatches messages on an I/O thread (running a
-//    |MessageLoopForIO|.
-//  - Provides a thread-safe way of writing messages (|WriteMessage()|);
-//    writing/queueing messages will not block and is atomic from the point of
-//    view of the caller. If necessary, messages are queued (to be written on
-//    the aforementioned thread).
-//
-// OS-specific implementation subclasses are to be instantiated using the
-// |Create()| static factory method.
-//
-// With the exception of |WriteMessage()|, this class is thread-unsafe (and in
-// general its methods should only be used on the I/O thread, i.e., the thread
-// on which |Init()| is called).
-class MOJO_SYSTEM_IMPL_EXPORT RawChannel {
- public:
-  virtual ~RawChannel();
-
-  // The |Delegate| is only accessed on the same thread as the message loop
-  // (passed in on creation).
-  class MOJO_SYSTEM_IMPL_EXPORT Delegate {
-   public:
-    enum Error {
-      // Failed read due to raw channel shutdown (e.g., on the other side).
-      ERROR_READ_SHUTDOWN,
-      // Failed read due to raw channel being broken (e.g., if the other side
-      // died without shutting down).
-      ERROR_READ_BROKEN,
-      // Received a bad message.
-      ERROR_READ_BAD_MESSAGE,
-      // Unknown read error.
-      ERROR_READ_UNKNOWN,
-      // Generic write error.
-      ERROR_WRITE
-    };
-
-    // Called when a message is read. This may call |Shutdown()| (on the
-    // |RawChannel|), but must not destroy it.
-    virtual void OnReadMessage(
-        const MessageInTransit::View& message_view,
-        embedder::ScopedPlatformHandleVectorPtr platform_handles) = 0;
-
-    // Called when there's a (fatal) error. This may call the raw channel's
-    // |Shutdown()|, but must not destroy it.
-    //
-    // For each raw channel, there'll be at most one |ERROR_READ_...| and at
-    // most one |ERROR_WRITE| notification. After |OnError(ERROR_READ_...)|,
-    // |OnReadMessage()| won't be called again.
-    virtual void OnError(Error error) = 0;
-
-   protected:
-    virtual ~Delegate() {}
-  };
-
-  // Static factory method. |handle| should be a handle to a
-  // (platform-appropriate) bidirectional communication channel (e.g., a socket
-  // on POSIX, a named pipe on Windows).
-  static scoped_ptr<RawChannel> Create(embedder::ScopedPlatformHandle handle);
-
-  // This must be called (on an I/O thread) before this object is used. Does
-  // *not* take ownership of |delegate|. Both the I/O thread and |delegate| must
-  // remain alive until |Shutdown()| is called (unless this fails); |delegate|
-  // will no longer be used after |Shutdown()|. Returns true on success. On
-  // failure, |Shutdown()| should *not* be called.
-  bool Init(Delegate* delegate);
-
-  // This must be called (on the I/O thread) before this object is destroyed.
-  void Shutdown();
-
-  // Writes the given message (or schedules it to be written). |message| must
-  // have no |Dispatcher|s still attached (i.e.,
-  // |SerializeAndCloseDispatchers()| should have been called). This method is
-  // thread-safe and may be called from any thread. Returns true on success.
-  bool WriteMessage(scoped_ptr<MessageInTransit> message);
-
-  // Returns true if the write buffer is empty (i.e., all messages written using
-  // |WriteMessage()| have actually been sent.
-  // TODO(vtl): We should really also notify our delegate when the write buffer
-  // becomes empty (or something like that).
-  bool IsWriteBufferEmpty();
-
-  // Returns the amount of space needed in the |MessageInTransit|'s
-  // |TransportData|'s "platform handle table" per platform handle (to be
-  // attached to a message). (This amount may be zero.)
-  virtual size_t GetSerializedPlatformHandleSize() const = 0;
-
- protected:
-  // Result of I/O operations.
-  enum IOResult {
-    IO_SUCCEEDED,
-    // Failed due to a (probably) clean shutdown (e.g., of the other end).
-    IO_FAILED_SHUTDOWN,
-    // Failed due to the connection being broken (e.g., the other end dying).
-    IO_FAILED_BROKEN,
-    // Failed due to some other (unexpected) reason.
-    IO_FAILED_UNKNOWN,
-    IO_PENDING
-  };
-
-  class MOJO_SYSTEM_IMPL_EXPORT ReadBuffer {
-   public:
-    ReadBuffer();
-    ~ReadBuffer();
-
-    void GetBuffer(char** addr, size_t* size);
-
-   private:
-    friend class RawChannel;
-
-    // We store data from |[Schedule]Read()|s in |buffer_|. The start of
-    // |buffer_| is always aligned with a message boundary (we will copy memory
-    // to ensure this), but |buffer_| may be larger than the actual number of
-    // bytes we have.
-    std::vector<char> buffer_;
-    size_t num_valid_bytes_;
-
-    DISALLOW_COPY_AND_ASSIGN(ReadBuffer);
-  };
-
-  class MOJO_SYSTEM_IMPL_EXPORT WriteBuffer {
-   public:
-    struct Buffer {
-      const char* addr;
-      size_t size;
-    };
-
-    explicit WriteBuffer(size_t serialized_platform_handle_size);
-    ~WriteBuffer();
-
-    // Returns true if there are (more) platform handles to be sent (from the
-    // front of |message_queue_|).
-    bool HavePlatformHandlesToSend() const;
-    // Gets platform handles to be sent (from the front of |message_queue_|).
-    // This should only be called if |HavePlatformHandlesToSend()| returned
-    // true. There are two components to this: the actual |PlatformHandle|s
-    // (which should be closed once sent) and any additional serialization
-    // information (which will be embedded in the message's data; there are
-    // |GetSerializedPlatformHandleSize()| bytes per handle). Once all platform
-    // handles have been sent, the message data should be written next (see
-    // |GetBuffers()|).
-    void GetPlatformHandlesToSend(size_t* num_platform_handles,
-                                  embedder::PlatformHandle** platform_handles,
-                                  void** serialization_data);
-
-    // Gets buffers to be written. These buffers will always come from the front
-    // of |message_queue_|. Once they are completely written, the front
-    // |MessageInTransit| should be popped (and destroyed); this is done in
-    // |OnWriteCompletedNoLock()|.
-    void GetBuffers(std::vector<Buffer>* buffers) const;
-
-   private:
-    friend class RawChannel;
-
-    const size_t serialized_platform_handle_size_;
-
-    // TODO(vtl): When C++11 is available, switch this to a deque of
-    // |scoped_ptr|/|unique_ptr|s.
-    std::deque<MessageInTransit*> message_queue_;
-    // Platform handles are sent before the message data, but doing so may
-    // require several passes. |platform_handles_offset_| indicates the position
-    // in the first message's vector of platform handles to send next.
-    size_t platform_handles_offset_;
-    // The first message's data may have been partially sent. |data_offset_|
-    // indicates the position in the first message's data to start the next
-    // write.
-    size_t data_offset_;
-
-    DISALLOW_COPY_AND_ASSIGN(WriteBuffer);
-  };
-
-  RawChannel();
-
-  // |result| must not be |IO_PENDING|. Must be called on the I/O thread WITHOUT
-  // |write_lock_| held.
-  void OnReadCompleted(IOResult io_result, size_t bytes_read);
-  // |result| must not be |IO_PENDING|. Must be called on the I/O thread WITHOUT
-  // |write_lock_| held.
-  void OnWriteCompleted(IOResult io_result,
-                        size_t platform_handles_written,
-                        size_t bytes_written);
-
-  base::MessageLoopForIO* message_loop_for_io() { return message_loop_for_io_; }
-  base::Lock& write_lock() { return write_lock_; }
-
-  // Should only be called on the I/O thread.
-  ReadBuffer* read_buffer() { return read_buffer_.get(); }
-
-  // Only called under |write_lock_|.
-  WriteBuffer* write_buffer_no_lock() {
-    write_lock_.AssertAcquired();
-    return write_buffer_.get();
-  }
-
-  // Adds |message| to the write message queue. Implementation subclasses may
-  // override this to add any additional "control" messages needed. This is
-  // called (on any thread) with |write_lock_| held.
-  virtual void EnqueueMessageNoLock(scoped_ptr<MessageInTransit> message);
-
-  // Handles any control messages targeted to the |RawChannel| (or
-  // implementation subclass). Implementation subclasses may override this to
-  // handle any implementation-specific control messages, but should call
-  // |RawChannel::OnReadMessageForRawChannel()| for any remaining messages.
-  // Returns true on success and false on error (e.g., invalid control message).
-  // This is only called on the I/O thread.
-  virtual bool OnReadMessageForRawChannel(
-      const MessageInTransit::View& message_view);
-
-  // Reads into |read_buffer()|.
-  // This class guarantees that:
-  // - the area indicated by |GetBuffer()| will stay valid until read completion
-  //   (but please also see the comments for |OnShutdownNoLock()|);
-  // - a second read is not started if there is a pending read;
-  // - the method is called on the I/O thread WITHOUT |write_lock_| held.
-  //
-  // The implementing subclass must guarantee that:
-  // - |bytes_read| is untouched unless |Read()| returns |IO_SUCCEEDED|;
-  // - if the method returns |IO_PENDING|, |OnReadCompleted()| will be called on
-  //   the I/O thread to report the result, unless |Shutdown()| is called.
-  virtual IOResult Read(size_t* bytes_read) = 0;
-  // Similar to |Read()|, except that the implementing subclass must also
-  // guarantee that the method doesn't succeed synchronously, i.e., it only
-  // returns |IO_FAILED_...| or |IO_PENDING|.
-  virtual IOResult ScheduleRead() = 0;
-
-  // Called by |OnReadCompleted()| to get the platform handles associated with
-  // the given platform handle table (from a message). This should only be
-  // called when |num_platform_handles| is nonzero. Returns null if the
-  // |num_platform_handles| handles are not available. Only called on the I/O
-  // thread (without |write_lock_| held).
-  virtual embedder::ScopedPlatformHandleVectorPtr GetReadPlatformHandles(
-      size_t num_platform_handles,
-      const void* platform_handle_table) = 0;
-
-  // Writes contents in |write_buffer_no_lock()|.
-  // This class guarantees that:
-  // - the |PlatformHandle|s given by |GetPlatformHandlesToSend()| and the
-  //   buffer(s) given by |GetBuffers()| will remain valid until write
-  //   completion (see also the comments for |OnShutdownNoLock()|);
-  // - a second write is not started if there is a pending write;
-  // - the method is called under |write_lock_|.
-  //
-  // The implementing subclass must guarantee that:
-  // - |platform_handles_written| and |bytes_written| are untouched unless
-  //   |WriteNoLock()| returns |IO_SUCCEEDED|;
-  // - if the method returns |IO_PENDING|, |OnWriteCompleted()| will be called
-  //   on the I/O thread to report the result, unless |Shutdown()| is called.
-  virtual IOResult WriteNoLock(size_t* platform_handles_written,
-                               size_t* bytes_written) = 0;
-  // Similar to |WriteNoLock()|, except that the implementing subclass must also
-  // guarantee that the method doesn't succeed synchronously, i.e., it only
-  // returns |IO_FAILED_...| or |IO_PENDING|.
-  virtual IOResult ScheduleWriteNoLock() = 0;
-
-  // Must be called on the I/O thread WITHOUT |write_lock_| held.
-  virtual bool OnInit() = 0;
-  // On shutdown, passes the ownership of the buffers to subclasses, which may
-  // want to preserve them if there are pending read/write. Must be called on
-  // the I/O thread under |write_lock_|.
-  virtual void OnShutdownNoLock(scoped_ptr<ReadBuffer> read_buffer,
-                                scoped_ptr<WriteBuffer> write_buffer) = 0;
-
- private:
-  // Converts an |IO_FAILED_...| for a read to a |Delegate::Error|.
-  static Delegate::Error ReadIOResultToError(IOResult io_result);
-
-  // Calls |delegate_->OnError(error)|. Must be called on the I/O thread WITHOUT
-  // |write_lock_| held.
-  void CallOnError(Delegate::Error error);
-
-  // If |io_result| is |IO_SUCCESS|, updates the write buffer and schedules a
-  // write operation to run later if there is more to write. If |io_result| is
-  // failure or any other error occurs, cancels pending writes and returns
-  // false. Must be called under |write_lock_| and only if |write_stopped_| is
-  // false.
-  bool OnWriteCompletedNoLock(IOResult io_result,
-                              size_t platform_handles_written,
-                              size_t bytes_written);
-
-  // Set in |Init()| and never changed (hence usable on any thread without
-  // locking):
-  base::MessageLoopForIO* message_loop_for_io_;
-
-  // Only used on the I/O thread:
-  Delegate* delegate_;
-  bool read_stopped_;
-  scoped_ptr<ReadBuffer> read_buffer_;
-
-  base::Lock write_lock_;  // Protects the following members.
-  bool write_stopped_;
-  scoped_ptr<WriteBuffer> write_buffer_;
-
-  // This is used for posting tasks from write threads to the I/O thread. It
-  // must only be accessed under |write_lock_|. The weak pointers it produces
-  // are only used/invalidated on the I/O thread.
-  base::WeakPtrFactory<RawChannel> weak_ptr_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(RawChannel);
-};
-
-}  // namespace system
-}  // namespace mojo
-
-#endif  // MOJO_SYSTEM_RAW_CHANNEL_H_