Revert "Move mojo edk into mojo/edk"

mojo/edk/system/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_EDK_SYSTEM_CHANNEL_H_
-#define MOJO_EDK_SYSTEM_CHANNEL_H_
-
-#include <stdint.h>
-
-#include "base/compiler_specific.h"
-#include "base/containers/hash_tables.h"
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/strings/string_piece.h"
-#include "base/synchronization/lock.h"
-#include "base/threading/thread_checker.h"
-#include "mojo/edk/embedder/scoped_platform_handle.h"
-#include "mojo/edk/system/channel_endpoint.h"
-#include "mojo/edk/system/message_in_transit.h"
-#include "mojo/edk/system/message_pipe.h"
-#include "mojo/edk/system/raw_channel.h"
-#include "mojo/edk/system/system_impl_export.h"
-#include "mojo/public/c/system/types.h"
-
-namespace mojo {
-
-namespace embedder {
-class PlatformSupport;
-}
-
-namespace system {
-
-class ChannelEndpoint;
-
-// This class is mostly thread-safe. It must be created on an I/O thread.
-// |Init()| must be called on that same thread before it becomes thread-safe (in
-// particular, before references are given to any other thread) and |Shutdown()|
-// must be called on that same thread before destruction. Its public methods are
-// otherwise thread-safe. (Many private methods are restricted to the creation
-// thread.) It may be destroyed on any thread, in the sense that the last
-// reference to it may be released on any thread, with the proviso that
-// |Shutdown()| must have been called first (so the pattern is that a "main"
-// reference is kept on its creation thread and is released after |Shutdown()|
-// is called, but other threads may have temporarily "dangling" references).
-//
-// Note the lock order (in order of allowable acquisition): |MessagePipe|,
-// |ChannelEndpoint|, |Channel|. Thus |Channel| may not call into
-// |ChannelEndpoint| with |Channel|'s lock held.
-class MOJO_SYSTEM_IMPL_EXPORT Channel
-    : public base::RefCountedThreadSafe<Channel>,
-      public RawChannel::Delegate {
- public:
-  // The first message pipe endpoint attached will have this as its local ID.
-  static const MessageInTransit::EndpointId kBootstrapEndpointId = 1;
-
-  // |platform_support| (typically owned by |Core|) must remain alive until
-  // after |Shutdown()| is called.
-  explicit Channel(embedder::PlatformSupport* platform_support);
-
-  // This must be called on the creation thread before any other methods are
-  // called, and before references to this object are given to any other
-  // threads. |raw_channel| should be uninitialized. Returns true on success. On
-  // failure, no other methods should be called (including |Shutdown()|).
-  bool Init(scoped_ptr<RawChannel> raw_channel);
-
-  // This must be called on the creation thread before destruction (which can
-  // happen on any thread).
-  void Shutdown();
-
-  // Signals that |Shutdown()| will be called soon (this may be called from any
-  // thread, unlike |Shutdown()|). Warnings will be issued if, e.g., messages
-  // are written after this is called; other warnings may be suppressed. (This
-  // may be called multiple times, or not at all.)
-  void WillShutdownSoon();
-
-  // Attaches the given endpoint to this channel. This assigns it a local ID,
-  // which it returns. The first endpoint attached will always have
-  // |kBootstrapEndpointId| as its local ID. (For bootstrapping, this occurs on
-  // both sides, so one should use |kBootstrapEndpointId| for the remote ID for
-  // the first message pipe across a channel.) Returns |kInvalidEndpointId| on
-  // failure.
-  // TODO(vtl): This should be combined with "run", and it should take a
-  // |ChannelEndpoint| instead.
-  // TODO(vtl): Maybe limit the number of attached message pipes.
-  MessageInTransit::EndpointId AttachEndpoint(
-      scoped_refptr<ChannelEndpoint> endpoint);
-
-  // Runs the message pipe with the given |local_id| (previously attached), with
-  // the given |remote_id| (negotiated using some other means, e.g., over an
-  // existing message pipe; see comments above for the bootstrap case). Returns
-  // false on failure, in particular if no message pipe with |local_id| is
-  // attached.
-  bool RunMessagePipeEndpoint(MessageInTransit::EndpointId local_id,
-                              MessageInTransit::EndpointId remote_id);
-
-  // Tells the other side of the channel to run a message pipe endpoint (which
-  // must already be attached); |local_id| and |remote_id| are relative to this
-  // channel (i.e., |local_id| is the other side's remote ID and |remote_id| is
-  // its local ID).
-  // TODO(vtl): Maybe we should just have a flag argument to
-  // |RunMessagePipeEndpoint()| that tells it to do this.
-  void RunRemoteMessagePipeEndpoint(MessageInTransit::EndpointId local_id,
-                                    MessageInTransit::EndpointId remote_id);
-
-  // This forwards |message| verbatim to |raw_channel_|.
-  bool WriteMessage(scoped_ptr<MessageInTransit> message);
-
-  // See |RawChannel::IsWriteBufferEmpty()|.
-  // TODO(vtl): Maybe we shouldn't expose this, and instead have a
-  // |FlushWriteBufferAndShutdown()| or something like that.
-  bool IsWriteBufferEmpty();
-
-  // This removes the message pipe/port's endpoint (with the given local ID and
-  // given remote ID, which should be |kInvalidEndpointId| if not yet running),
-  // returned by |AttachEndpoint()| from this channel. After this is called,
-  // |local_id| may be reused for another message pipe.
-  void DetachMessagePipeEndpoint(MessageInTransit::EndpointId local_id,
-                                 MessageInTransit::EndpointId remote_id);
-
-  // See |RawChannel::GetSerializedPlatformHandleSize()|.
-  size_t GetSerializedPlatformHandleSize() const;
-
-  embedder::PlatformSupport* platform_support() const {
-    return platform_support_;
-  }
-
- private:
-  friend class base::RefCountedThreadSafe<Channel>;
-  virtual ~Channel();
-
-  // |RawChannel::Delegate| implementation (only called on the creation thread):
-  virtual void OnReadMessage(
-      const MessageInTransit::View& message_view,
-      embedder::ScopedPlatformHandleVectorPtr platform_handles) override;
-  virtual void OnError(Error error) override;
-
-  // Helpers for |OnReadMessage| (only called on the creation thread):
-  void OnReadMessageForDownstream(
-      const MessageInTransit::View& message_view,
-      embedder::ScopedPlatformHandleVectorPtr platform_handles);
-  void OnReadMessageForChannel(
-      const MessageInTransit::View& message_view,
-      embedder::ScopedPlatformHandleVectorPtr platform_handles);
-
-  // Handles "remove message pipe endpoint" messages.
-  bool OnRemoveMessagePipeEndpoint(MessageInTransit::EndpointId local_id,
-                                   MessageInTransit::EndpointId remote_id);
-  // Handles "remove message pipe endpoint ack" messages.
-  bool OnRemoveMessagePipeEndpointAck(MessageInTransit::EndpointId local_id);
-
-  // Handles errors (e.g., invalid messages) from the remote side. Callable from
-  // any thread.
-  void HandleRemoteError(const base::StringPiece& error_message);
-  // Handles internal errors/failures from the local side. Callable from any
-  // thread.
-  void HandleLocalError(const base::StringPiece& error_message);
-
-  // Helper to send channel control messages. Returns true on success. Should be
-  // called *without* |lock_| held. Callable from any thread.
-  bool SendControlMessage(MessageInTransit::Subtype subtype,
-                          MessageInTransit::EndpointId source_id,
-                          MessageInTransit::EndpointId destination_id);
-
-  base::ThreadChecker creation_thread_checker_;
-
-  embedder::PlatformSupport* const platform_support_;
-
-  // Note: |MessagePipe|s MUST NOT be used under |lock_|. I.e., |lock_| can only
-  // be acquired after |MessagePipe::lock_|, never before. Thus to call into a
-  // |MessagePipe|, a reference to the |MessagePipe| should be acquired from
-  // |local_id_to_endpoint_map_| under |lock_| and then the lock released.
-  base::Lock lock_;  // Protects the members below.
-
-  scoped_ptr<RawChannel> raw_channel_;
-  bool is_running_;
-  // Set when |WillShutdownSoon()| is called.
-  bool is_shutting_down_;
-
-  typedef base::hash_map<MessageInTransit::EndpointId,
-                         scoped_refptr<ChannelEndpoint>> IdToEndpointMap;
-  IdToEndpointMap local_id_to_endpoint_map_;
-  // The next local ID to try (when allocating new local IDs). Note: It should
-  // be checked for existence before use.
-  MessageInTransit::EndpointId next_local_id_;
-
-  DISALLOW_COPY_AND_ASSIGN(Channel);
-};
-
-}  // namespace system
-}  // namespace mojo
-
-#endif  // MOJO_EDK_SYSTEM_CHANNEL_H_