Ensure that in-flight message pipes are always closed and the other end is notified.

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 <stddef.h>
 #include <stdint.h>
 
@@ skipping 75 matching lines @@
       size_t size,
       PlatformHandleVector* platform_handles);
 
  private:
   // 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 CloseOnIOAndRelease();
   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,
@@ skipping 58 matching lines @@
   size_t serialized_message_fds_length_;
   ScopedPlatformHandle serialized_platform_handle_;
 
   // The following members are only used when transferable_ is false;
 
   // 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 {
+    // The pipe_id hasn't been bound to this object yet until it's read,
+    // written, or waited on.
     WAITING_FOR_READ_OR_WRITE,
+    // This object was interacted with, so the pipe_id has been bound and we are
+    // waiting for the broker to connect both sides.
     CONNECT_CALLED,
+    // We have a connection to the other end of the message pipe.
     CONNECTED,
+    // This object has been closed before it's connected. To ensure that the
+    // other end receives a closed message from this end, we've initiated
+    // connecting and will close after it succeeds.
     WAITING_FOR_CONNECT_TO_CLOSE,
+    // The message pipe is closed.
     CLOSED,
+    // The message pipe has been transferred.
     SERIALISED,
   };
 
   NonTransferableState non_transferable_state_;
   // Messages that were written while we were waiting to get a RawChannel.
   MessageInTransitQueue non_transferable_outgoing_message_queue_;
   scoped_ptr<base::debug::StackTrace> non_transferable_bound_stack_;
 
 
   // 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_;
+  // When this object is closed, it has to wait to flush any pending messages
+  // from the other side to ensure that any in-queue message pipes are closed.
+  // If this is true, we have already sent the other side the request.
+  bool close_requested_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MessagePipeDispatcher);
 };
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_MESSAGE_PIPE_DISPATCHER_H_