Add multiplexing of message pipes in the new EDK.

mojo/edk/system/message_pipe_dispatcher.cc

Index: mojo/edk/system/message_pipe_dispatcher.cc
diff --git a/mojo/edk/system/message_pipe_dispatcher.cc b/mojo/edk/system/message_pipe_dispatcher.cc
index 6ebab7489a799f655ccadf5768ed5510073fba44..e61b31a3e0af24204643e4641ae2a0edb85f2f5e 100644
--- a/mojo/edk/system/message_pipe_dispatcher.cc
+++ b/mojo/edk/system/message_pipe_dispatcher.cc
@@ -25,10 +25,13 @@ namespace {
 const size_t kInvalidMessagePipeHandleIndex = static_cast<size_t>(-1);
 
 struct MOJO_ALIGNAS(8) SerializedMessagePipeHandleDispatcher {
+  bool transferable;
+  bool write_error;
+  uint64_t pipe_id;  // If transferable is false.
+  // The following members are only set if transferable is true.
   // Could be |kInvalidMessagePipeHandleIndex| if the other endpoint of the MP
   // was closed.
   size_t platform_handle_index;
-  bool write_error;
 
   size_t shared_memory_handle_index;  // (Or |kInvalidMessagePipeHandleIndex|.)
   uint32_t shared_memory_size;
@@ -90,7 +93,8 @@ MojoResult MessagePipeDispatcher::ValidateCreateOptions(
     const MojoCreateMessagePipeOptions* in_options,
     MojoCreateMessagePipeOptions* out_options) {
   const MojoCreateMessagePipeOptionsFlags kKnownFlags =
-      MOJO_CREATE_MESSAGE_PIPE_OPTIONS_FLAG_NONE;
+      MOJO_CREATE_MESSAGE_PIPE_OPTIONS_FLAG_NONE |
+      MOJO_CREATE_MESSAGE_PIPE_OPTIONS_FLAG_TRANSFERABLE;
 
   *out_options = kDefaultCreateOptions;
   if (!in_options)
@@ -119,6 +123,7 @@ void MessagePipeDispatcher::Init(
     char* serialized_write_buffer, size_t serialized_write_buffer_size,
     std::vector<int>* serialized_read_fds,
     std::vector<int>* serialized_write_fds) {
+  CHECK(transferable_);
   if (message_pipe.get().is_valid()) {
     channel_ = RawChannel::Create(message_pipe.Pass());
 
@@ -132,8 +137,14 @@ void MessagePipeDispatcher::Init(
   }
 }
 
+void MessagePipeDispatcher::InitNonTransferable(uint64_t pipe_id) {
+  CHECK(!transferable_);
+  pipe_id_ = pipe_id;
+}
+
 void MessagePipeDispatcher::InitOnIO() {
   base::AutoLock locker(lock());
+  CHECK(transferable_);
   calling_init_ = true;
   if (channel_)
     channel_->Init(this);
@@ -142,10 +153,23 @@ void MessagePipeDispatcher::InitOnIO() {
 
 void MessagePipeDispatcher::CloseOnIO() {
   base::AutoLock locker(lock());
-
-  if (channel_) {
-    channel_->Shutdown();
-    channel_ = nullptr;
+  if (transferable_) {
+    if (channel_) {
+      channel_->Shutdown();
+      channel_ = nullptr;
+    }
+  } else {
+    if (non_transferable_state_ == CONNECT_CALLED) {
+      // We can't cancel the pending request yet, since the other side of the
+      // message pipe would want to get pending outgoing messages (if any) or
+      // at least know that this end was closed. So keep this object alive until
+      // then.
+      AddRef();
+    } else if (non_transferable_state_ == CONNECTED) {
+      internal::g_broker->CloseMessagePipe(pipe_id_, this);
+      non_transferable_state_ = CLOSED;
+      channel_ = nullptr;
+    }
   }
 }
 
@@ -153,6 +177,31 @@ Dispatcher::Type MessagePipeDispatcher::GetType() const {
   return Type::MESSAGE_PIPE;
 }
 
+void MessagePipeDispatcher::GotNonTransferableChannel(RawChannel* channel) {
+  base::AutoLock locker(lock());
+  channel_ = channel;
+  while (!non_transferable_outgoing_message_queue_.IsEmpty()) {
+    channel_->WriteMessage(
+        non_transferable_outgoing_message_queue_.GetMessage());
+  }
+
+  if (is_closed()) {
+    CHECK_EQ(non_transferable_state_, CONNECT_CALLED);
+    // We kept this object alive until it's connected, we can release it now.
+    // Since we're in a callback from the Broker, call it asynchronously.
+    internal::g_io_thread_task_runner->PostTask(
+        FROM_HERE,
+        base::Bind(&Broker::CloseMessagePipe,
+                   base::Unretained(internal::g_broker), pipe_id_,
+                   base::Unretained(this)));
+    non_transferable_state_ = CLOSED;
+    channel_ = nullptr;
+    base::MessageLoop::current()->ReleaseSoon(FROM_HERE, this);
+  } else {
+    non_transferable_state_ = CONNECTED;
+  }
+}
+
 #if defined(OS_WIN)
 // TODO(jam): this is copied from RawChannelWin till I figure out what's the
 // best way we want to share this.
@@ -186,6 +235,14 @@ scoped_refptr<MessagePipeDispatcher> MessagePipeDispatcher::Deserialize(
 
   const SerializedMessagePipeHandleDispatcher* serialization =
       static_cast<const SerializedMessagePipeHandleDispatcher*>(source);
+
+  scoped_refptr<MessagePipeDispatcher> rv(
+      new MessagePipeDispatcher(serialization->transferable));
+  if (!rv->transferable_) {
+    rv->InitNonTransferable(serialization->pipe_id);
+    return rv;
+  }
+
   if (serialization->shared_memory_size !=
       (serialization->serialized_read_buffer_size +
        serialization->serialized_write_buffer_size +
@@ -233,8 +290,6 @@ scoped_refptr<MessagePipeDispatcher> MessagePipeDispatcher::Deserialize(
     }
   }
 
-  scoped_refptr<MessagePipeDispatcher> rv(
-      Create(MessagePipeDispatcher::kDefaultCreateOptions));
   rv->write_error_ = serialization->write_error;
 
   std::vector<int> serialized_read_fds;
@@ -333,14 +388,17 @@ scoped_refptr<MessagePipeDispatcher> MessagePipeDispatcher::Deserialize(
   return rv;
 }
 
-MessagePipeDispatcher::MessagePipeDispatcher()
+MessagePipeDispatcher::MessagePipeDispatcher(bool transferable)
     : channel_(nullptr),
-      serialized_(false),
       serialized_read_fds_length_(0u),
       serialized_write_fds_length_(0u),
       serialized_message_fds_length_(0u),
+      pipe_id_(0),
+      non_transferable_state_(WAITING_FOR_READ_OR_WRITE),
+      serialized_(false),
       calling_init_(false),
-      write_error_(false) {
+      write_error_(false),
+      transferable_(transferable) {
 }
 
 MessagePipeDispatcher::~MessagePipeDispatcher() {
@@ -369,6 +427,15 @@ void MessagePipeDispatcher::CloseImplNoLock() {
 }
 
 void MessagePipeDispatcher::SerializeInternal() {
+  serialized_ = true;
+  if (!transferable_) {
+    CHECK(non_transferable_state_ == WAITING_FOR_READ_OR_WRITE)
+        << "Non transferable message pipe being sent after read/write. "
+        << "MOJO_CREATE_MESSAGE_PIPE_OPTIONS_FLAG_TRANSFERABLE must be used if "
+        << "the pipe can be sent after it's read or written.";
+    return;
+  }
+
   // We need to stop watching handle immediately, even though not on IO thread,
   // so that other messages aren't read after this.
   std::vector<int> serialized_read_fds, serialized_write_fds;
@@ -385,8 +452,6 @@ void MessagePipeDispatcher::SerializeInternal() {
                           serialized_write_fds.end());
     serialized_write_fds_length_ = serialized_write_fds.size();
     channel_ = nullptr;
-    if (write_error)
-      write_error = true;
   } else {
     // It's valid that the other side wrote some data and closed its end.
   }
@@ -453,8 +518,6 @@ void MessagePipeDispatcher::SerializeInternal() {
     for (size_t i = 0; i < dispatchers.size(); ++i)
       dispatchers[i]->TransportEnded();
   }
-
-  serialized_ = true;
 }
 
 scoped_refptr<Dispatcher>
@@ -466,18 +529,24 @@ MessagePipeDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock() {
   // TODO(vtl): Currently, there are no options, so we just use

[yzshen1, 2015/12/03 23:37:50]

I think this comment is not useful anymore.

[jam, 2015/12/04 05:06:47]

Done.

   // |kDefaultCreateOptions|. Eventually, we'll have to duplicate the options
   // too.
-  scoped_refptr<MessagePipeDispatcher> rv = Create(kDefaultCreateOptions);
-  rv->serialized_platform_handle_ = serialized_platform_handle_.Pass();
-  serialized_message_queue_.swap(rv->serialized_message_queue_);
-  serialized_read_buffer_.swap(rv->serialized_read_buffer_);
-  serialized_write_buffer_.swap(rv->serialized_write_buffer_);
-  serialized_fds_.swap(rv->serialized_fds_);
-  rv->serialized_read_fds_length_ = serialized_read_fds_length_;
-  rv->serialized_write_fds_length_ = serialized_write_fds_length_;
-  rv->serialized_message_fds_length_ = serialized_message_fds_length_;
+  scoped_refptr<MessagePipeDispatcher> rv(
+      new MessagePipeDispatcher(transferable_));
   rv->serialized_ = true;
-  rv->write_error_ = write_error_;
-  return scoped_refptr<Dispatcher>(rv.get());
+  if (transferable_) {
+    rv->serialized_platform_handle_ = serialized_platform_handle_.Pass();
+    serialized_message_queue_.swap(rv->serialized_message_queue_);
+    serialized_read_buffer_.swap(rv->serialized_read_buffer_);
+    serialized_write_buffer_.swap(rv->serialized_write_buffer_);
+    serialized_fds_.swap(rv->serialized_fds_);
+    rv->serialized_read_fds_length_ = serialized_read_fds_length_;
+    rv->serialized_write_fds_length_ = serialized_write_fds_length_;
+    rv->serialized_message_fds_length_ = serialized_message_fds_length_;
+    rv->write_error_ = write_error_;
+  } else {
+    rv->pipe_id_ = pipe_id_;
+    rv->non_transferable_state_ = non_transferable_state_;
+  }
+  return rv;
 }
 
 MojoResult MessagePipeDispatcher::WriteMessageImplNoLock(
@@ -485,15 +554,17 @@ MojoResult MessagePipeDispatcher::WriteMessageImplNoLock(
     uint32_t num_bytes,
     std::vector<DispatcherTransport>* transports,
     MojoWriteMessageFlags flags) {
+  lock().AssertAcquired();
 
   DCHECK(!transports ||
          (transports->size() > 0 &&
           transports->size() <= GetConfiguration().max_message_num_handles));
 
-  lock().AssertAcquired();
-
-  if (!channel_ || write_error_)
+  if (write_error_ ||
+      (transferable_ && !channel_) ||
+      (!transferable_ && non_transferable_state_ == CLOSED)) {
     return MOJO_RESULT_FAILED_PRECONDITION;
+  }
 
   if (num_bytes > GetConfiguration().max_message_num_bytes)
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
@@ -506,7 +577,17 @@ MojoResult MessagePipeDispatcher::WriteMessageImplNoLock(
   }
 
   message->SerializeAndCloseDispatchers();
-  channel_->WriteMessage(message.Pass());
+  if (!transferable_)
+    message->set_route_id(pipe_id_);
+  if (!transferable_ &&
+      (non_transferable_state_ == WAITING_FOR_READ_OR_WRITE ||
+       non_transferable_state_ == CONNECT_CALLED)) {
+    if (non_transferable_state_ == WAITING_FOR_READ_OR_WRITE)
+      RequestNontransferableChannel();
+    non_transferable_outgoing_message_queue_.AddMessage(message.Pass());
+  } else {
+    channel_->WriteMessage(message.Pass());
+  }
 
   return MOJO_RESULT_OK;
 }
@@ -518,8 +599,14 @@ MojoResult MessagePipeDispatcher::ReadMessageImplNoLock(
     uint32_t* num_dispatchers,
     MojoReadMessageFlags flags) {
   lock().AssertAcquired();
-  if (channel_)
+  if (channel_) {
     channel_->EnsureLazyInitialized();
+  } else if (!transferable_ &&
+             non_transferable_state_ == WAITING_FOR_READ_OR_WRITE) {
+    RequestNontransferableChannel();
+    return MOJO_RESULT_SHOULD_WAIT;
+  }
+
   DCHECK(!dispatchers || dispatchers->empty());
 
   const uint32_t max_bytes = !num_bytes ? 0 : *num_bytes;
@@ -583,14 +670,21 @@ HandleSignalsState MessagePipeDispatcher::GetHandleSignalsStateImplNoLock()
   HandleSignalsState rv;
   if (!message_queue_.IsEmpty())
     rv.satisfied_signals |= MOJO_HANDLE_SIGNAL_READABLE;
-  if (channel_ || !message_queue_.IsEmpty())
+  if (!message_queue_.IsEmpty() ||
+      (transferable_ && channel_) ||
+      (!transferable_ && non_transferable_state_ != CLOSED))
     rv.satisfiable_signals |= MOJO_HANDLE_SIGNAL_READABLE;
-  if (channel_ && !write_error_) {
+  if (!write_error_ &&
+      ((transferable_ && channel_) ||
+       (!transferable_ && non_transferable_state_ != CLOSED))) {
     rv.satisfied_signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
     rv.satisfiable_signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
   }
-  if (!channel_ || write_error_)
+  if (write_error_ ||
+      (transferable_ && !channel_) ||
+       (!transferable_ && non_transferable_state_ == CLOSED)) {
     rv.satisfied_signals |= MOJO_HANDLE_SIGNAL_PEER_CLOSED;
+  }
   rv.satisfiable_signals |= MOJO_HANDLE_SIGNAL_PEER_CLOSED;
   return rv;
 }
@@ -601,8 +695,13 @@ MojoResult MessagePipeDispatcher::AddAwakableImplNoLock(
     uintptr_t context,
     HandleSignalsState* signals_state) {
   lock().AssertAcquired();
-  if (channel_)
+  if (channel_) {
     channel_->EnsureLazyInitialized();
+  } else if (!transferable_ &&
+             non_transferable_state_ == WAITING_FOR_READ_OR_WRITE) {
+    RequestNontransferableChannel();
+  }
+
   HandleSignalsState state = GetHandleSignalsStateImplNoLock();
   if (state.satisfies(signals)) {
     if (signals_state)
@@ -653,6 +752,8 @@ bool MessagePipeDispatcher::EndSerializeAndCloseImplNoLock(
   CloseImplNoLock();
   SerializedMessagePipeHandleDispatcher* serialization =
       static_cast<SerializedMessagePipeHandleDispatcher*>(destination);
+  serialization->transferable = transferable_;
+  serialization->pipe_id = pipe_id_;
   if (serialized_platform_handle_.is_valid()) {
     serialization->platform_handle_index = platform_handles->size();
     platform_handles->push_back(serialized_platform_handle_.release());
@@ -796,7 +897,18 @@ void MessagePipeDispatcher::OnError(Error error) {
     // called, that is safe since this class always does a PostTask to the IO
     // thread to self destruct.
     if (channel_ && error != ERROR_WRITE) {
-      channel_->Shutdown();
+      if (transferable_) {
+        channel_->Shutdown();
+      } else {
+        CHECK_NE(non_transferable_state_, CLOSED);
+        // Since we're in a callback from the Broker, call it asynchronously.
+        internal::g_io_thread_task_runner->PostTask(
+            FROM_HERE,
+            base::Bind(&Broker::CloseMessagePipe,
+                       base::Unretained(internal::g_broker), pipe_id_,
+                       base::Unretained(this)));
+        non_transferable_state_ = CLOSED;
+      }
       channel_ = nullptr;
     }
     awakable_list_.AwakeForStateChange(GetHandleSignalsStateImplNoLock());
@@ -849,5 +961,19 @@ MojoResult MessagePipeDispatcher::AttachTransportsNoLock(
   return MOJO_RESULT_OK;
 }
 
+void MessagePipeDispatcher::RequestNontransferableChannel() {
+  lock().AssertAcquired();
+  CHECK(!transferable_);
+  CHECK_EQ(non_transferable_state_, WAITING_FOR_READ_OR_WRITE);
+  non_transferable_state_ = CONNECT_CALLED;
+
+  // PostTask since the broker can call us back synchronously.
+  internal::g_io_thread_task_runner->PostTask(
+      FROM_HERE,
+      base::Bind(&Broker::ConnectMessagePipe,
+                 base::Unretained(internal::g_broker), pipe_id_,
+                 base::Unretained(this)));
+}
+
 }  // namespace edk
 }  // namespace mojo