Add a Mojo EDK for Chrome that uses one OS pipe per message pipe.

mojo/edk/system/message_pipe_dispatcher.h

Index: mojo/edk/system/message_pipe_dispatcher.h
diff --git a/mojo/edk/system/message_pipe_dispatcher.h b/mojo/edk/system/message_pipe_dispatcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..c47b55050ab670a21ced73d0a19903b563ba8136
--- /dev/null
+++ b/mojo/edk/system/message_pipe_dispatcher.h
@@ -0,0 +1,145 @@
+// Copyright 2015 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_MESSAGE_PIPE_DISPATCHER_H_
+#define MOJO_EDK_SYSTEM_MESSAGE_PIPE_DISPATCHER_H_
+
+#include "base/memory/ref_counted.h"
+#include "mojo/edk/embedder/platform_channel_pair.h"
+#include "mojo/edk/system/awakable_list.h"
+#include "mojo/edk/system/dispatcher.h"
+#include "mojo/edk/system/raw_channel.h"
+#include "mojo/edk/system/system_impl_export.h"
+#include "mojo/public/cpp/system/macros.h"
+
+namespace mojo {
+namespace edk {
+
+// This is the |Dispatcher| implementation for message pipes (created by the
+// Mojo primitive |MojoCreateMessagePipe()|). This class is thread-safe.
+class MOJO_SYSTEM_IMPL_EXPORT MessagePipeDispatcher final
+    : public Dispatcher, public RawChannel::Delegate {
+ public:
+  // The default options to use for |MojoCreateMessagePipe()|. (Real uses
+  // should obtain this via |ValidateCreateOptions()| with a null |in_options|;
+  // this is exposed directly for testing convenience.)
+  static const MojoCreateMessagePipeOptions kDefaultCreateOptions;
+
+  static scoped_refptr<MessagePipeDispatcher> Create(
+      const MojoCreateMessagePipeOptions& /*validated_options*/) {
+    return make_scoped_refptr(new MessagePipeDispatcher());
+  }
+
+  // Validates and/or sets default options for |MojoCreateMessagePipeOptions|.
+  // If non-null, |in_options| must point to a struct of at least
+  // |in_options->struct_size| bytes. |out_options| must point to a (current)
+  // |MojoCreateMessagePipeOptions| and will be entirely overwritten on success
+  // (it may be partly overwritten on failure).
+  static MojoResult ValidateCreateOptions(
+      const MojoCreateMessagePipeOptions* in_options,
+      MojoCreateMessagePipeOptions* out_options);
+
+  // Must be called before any other methods. (This method is not thread-safe.)
+  void Init(ScopedPlatformHandle message_pipe);
+
+  // |Dispatcher| public methods:
+  Type GetType() const override;
+
+  // The "opposite" of |SerializeAndClose()|. (Typically this is called by
+  // |Dispatcher::Deserialize()|.)
+  static scoped_refptr<MessagePipeDispatcher> Deserialize(
+      const void* source,
+      size_t size,
+      PlatformHandleVector* platform_handles);
+
+ private:
+  MessagePipeDispatcher();
+  ~MessagePipeDispatcher() override;
+
+  void InitWithReadBuffer(ScopedPlatformHandle message_pipe,
+                          char* data,
+                          size_t size);
+
+  void InitOnIO();
+  void CloseOnIO();
+
+  // |Dispatcher| protected methods:
+  void CancelAllAwakablesNoLock() override;
+  void CloseImplNoLock() override;
+  scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
+      override;
+  MojoResult WriteMessageImplNoLock(
+      const void* bytes,
+      uint32_t num_bytes,
+      std::vector<DispatcherTransport>* transports,
+      MojoWriteMessageFlags flags) override;
+  MojoResult ReadMessageImplNoLock(void* bytes,
+                                   uint32_t* num_bytes,
+                                   DispatcherVector* dispatchers,
+                                   uint32_t* num_dispatchers,
+                                   MojoReadMessageFlags flags) override;
+  HandleSignalsState GetHandleSignalsStateImplNoLock() const override;
+  MojoResult AddAwakableImplNoLock(Awakable* awakable,
+                                   MojoHandleSignals signals,
+                                   uint32_t context,
+                                   HandleSignalsState* signals_state) override;
+  void RemoveAwakableImplNoLock(Awakable* awakable,
+                                HandleSignalsState* signals_state) override;
+  void StartSerializeImplNoLock(size_t* max_size,
+                                size_t* max_platform_handles) override;
+  bool EndSerializeAndCloseImplNoLock(
+      void* destination,
+      size_t* actual_size,
+      PlatformHandleVector* platform_handles) override;
+  void TransportStarted() override;
+  void TransportEnded() override;
+
+  // |RawChannel::Delegate methods:
+  void OnReadMessage(
+    const MessageInTransit::View& message_view,
+    ScopedPlatformHandleVectorPtr platform_handles) override;
+  void OnError(Error error) override;
+
+  // Calls ReleaseHandle and serializes the raw channel. This is split into a
+  // function because it's called in two different ways:
+  // 1) When serializing "live" dispatchers that are passed to MojoWriteMessage,
+  // CreateEquivalentDispatcherAndCloseImplNoLock calls this.
+  // 2) When serializing dispatchers that are attached to deserialized messages
+  // which haven't been consumed by MojoReadMessage, StartSerializeImplNoLock
+  // calls this.
+  void SerializeInternal();
+
+  MojoResult AttachTransportsNoLock(
+      MessageInTransit* message,
+      std::vector<DispatcherTransport>* transports);
+
+  // Protected by |lock()|:
+  RawChannel* channel_;
+
+  // Queue of incoming messages that we read from RawChannel but haven't been
+  // consumed through MojoReadMessage yet.
+  MessageInTransitQueue message_queue_;
+  // When sending MP, contains serialized message_queue_.
+  bool serialized_;
+  // TODO(jam): stop using this and use shared memory instead since we are
+  // limited to 10K.
+  std::vector<char> serialized_message_queue_;
+  std::vector<char> serialized_read_buffer_;
+  PlatformHandle serialized_platform_handle_;
+  AwakableList awakable_list_;
+
+  // If DispatcherTransport is created. Must be set before lock() is called to
+  // avoid deadlocks with RawChannel calling us.
+  base::Lock started_transport_;
+
+  bool calling_init_;
+  bool error_;
+
+  MOJO_DISALLOW_COPY_AND_ASSIGN(MessagePipeDispatcher);
+};
+
+}  // namespace edk
+}  // namespace mojo
+
+#endif  // MOJO_EDK_SYSTEM_MESSAGE_PIPE_DISPATCHER_H_