Add multiplexing of message pipes in the new EDK.

mojo/edk/system/message_pipe_dispatcher.h

 // 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/message_in_transit_queue.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());
+      const MojoCreateMessagePipeOptions& validated_options) {
+    return make_scoped_refptr(new MessagePipeDispatcher(
+        !!(validated_options.flags &
+           MOJO_CREATE_MESSAGE_PIPE_OPTIONS_FLAG_TRANSFERABLE)));
   }
 
   // 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);
 
+  // Initializes a transferable message pipe.
   // Must be called before any other methods. (This method is not thread-safe.)
   void Init(
       ScopedPlatformHandle message_pipe,
       char* serialized_read_buffer, size_t serialized_read_buffer_size,
       char* serialized_write_buffer, size_t serialized_write_buffer_size,
       std::vector<int>* serialized_read_fds,
       std::vector<int>* serialized_write_fds);
 
+  // Initializes a nontransferable message pipe.
+  void InitNonTransferable(uint64_t pipe_id);
+
   // |Dispatcher| public methods:
   Type GetType() const override;
 
+  // RawChannel::Delegate methods:
+  void OnReadMessage(
+      const MessageInTransit::View& message_view,
+      ScopedPlatformHandleVectorPtr platform_handles) override;
+  void OnError(Error error) override;
+
+  // Called by broker when a route is established between this
+  // MessagePipeDispatcher and another one. This object will receive messages
+  // sent to its pipe_id. It should tag all outgoing messages by calling
+  // MessageInTransit::set_route_id with pipe_id_.
+  void GotNonTransferableChannel(RawChannel* channel);
+
   // 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();
+  // See MOJO_CREATE_MESSAGE_PIPE_OPTIONS_FLAG_TRANSFERABLE's definition for an
+  // explanation of what is a transferable pipe.
+  explicit MessagePipeDispatcher(bool transferable);
   ~MessagePipeDispatcher() override;
 
   void InitOnIO();
   void CloseOnIO();
 
   // |Dispatcher| protected methods:
   void CancelAllAwakablesNoLock() override;
   void CloseImplNoLock() override;
   scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
       override;
@@ skipping 16 matching lines @@
                                 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);
 
+  // Called whenever a read or write is done on a non-transferable pipe, which
+  // "binds" the pipe id to this object.
+  void RequestNontransferableChannel();
+
   // 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_;
+
+  // The following members are only used when transferable_ is false;
+
   // When sending MP, contains serialized message_queue_.
-  bool serialized_;
   std::vector<char> serialized_message_queue_;
   std::vector<char> serialized_read_buffer_;
   std::vector<char> serialized_write_buffer_;
   // Contains FDs from (in this order): the read buffer, the write buffer, and
   // message queue.
   std::vector<int> serialized_fds_;
   size_t serialized_read_fds_length_;
   size_t serialized_write_fds_length_;
   size_t serialized_message_fds_length_;
   ScopedPlatformHandle serialized_platform_handle_;
+
+  // The following members are only used when transferable_ is true;
+
+  // The unique id shared by both ends of a non-transferable message pipe. This
+  // is held on until a read or write are done, and at that point it's used to
+  // get a RawChannel.
+  uint64_t pipe_id_;
+  enum NonTransferableState {
+    WAITING_FOR_READ_OR_WRITE,
+    CONNECT_CALLED,
+    CONNECTED,
+    WAITING_FOR_CONNECT_TO_CLOSE,
+    CLOSED,
+    SERIALISED,
+  };
+
+  NonTransferableState non_transferable_state_;
+  // Messages that were written while we were waiting to get a RawChannel.
+  MessageInTransitQueue non_transferable_outgoing_message_queue_;
+
+
+  // The following members are used for both modes of transferable_.
+
   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 serialized_;
   bool calling_init_;
   bool write_error_;
+  // Whether it can be sent after read or write.
+  bool transferable_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MessagePipeDispatcher);
 };
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_MESSAGE_PIPE_DISPATCHER_H_