Add multiplexing of message pipes in the new EDK.

mojo/edk/system/routed_raw_channel.cc

+// 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.
+
+#include "mojo/edk/system/routed_raw_channel.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "mojo/edk/embedder/embedder_internal.h"
+#include "mojo/edk/system/message_pipe_dispatcher.h"
+
+namespace mojo {
+namespace edk {
+
+namespace {
+const uint64_t kInternalRoutingId = 0;
+
+// These are messages sent over our internal routing id above, meant for the
+// other side's RoutedRawChannel to dispatch.
+enum InternalMessages {
+  ROUTE_CLOSED = 0,
+};
+}
+
+RoutedRawChannel::PendingMessage::PendingMessage() {
+}
+
+RoutedRawChannel::PendingMessage::~PendingMessage() {
+}
+
+RoutedRawChannel::RoutedRawChannel(
+    ScopedPlatformHandle handle,
+    const base::Callback<void(RoutedRawChannel*)>& destruct_callback)
+    : channel_(RawChannel::Create(handle.Pass())),
+      destruct_callback_(destruct_callback) {
+  internal::g_io_thread_task_runner->PostTask(
+        FROM_HERE,
+        base::Bind(&RawChannel::Init, base::Unretained(channel_), this));
+  internal::g_io_thread_task_runner->PostTask(
+        FROM_HERE,
+        base::Bind(&RawChannel::EnsureLazyInitialized,
+                   base::Unretained(channel_)));
+}
+
+void RoutedRawChannel::AddRoute(uint64_t pipe_id, MessagePipeDispatcher* pipe) {
+  CHECK_NE(pipe_id, kInternalRoutingId) << kInternalRoutingId << " is reserved";
+  base::AutoLock auto_lock(lock_);
+  CHECK(routes_.find(pipe_id) == routes_.end());
+  routes_[pipe_id] = pipe;
+
+  for (size_t i = 0; i < pending_messages_.size();) {
+    MessageInTransit::View view(pending_messages_[i]->message.size(),
+                                &pending_messages_[i]->message[0]);
+    if (view.route_id() == pipe_id) {
+      pipe->OnReadMessage(view, pending_messages_[i]->handles.Pass());
+      pending_messages_.erase(pending_messages_.begin() + i);
+    } else {
+      ++i;
+    }
+  }
+
+  if (close_routes_.find(pipe_id) != close_routes_.end())
+    pipe->OnError(ERROR_READ_SHUTDOWN);
+}
+
+void RoutedRawChannel::RemoveRoute(uint64_t pipe_id,
+                                   MessagePipeDispatcher* pipe) {
+  base::AutoLock auto_lock(lock_);
+  CHECK(routes_.find(pipe_id) != routes_.end());
+  CHECK_EQ(routes_[pipe_id], pipe);
+  routes_.erase(pipe_id);
+
+  // Only send a message to the other side to close the route if we hadn't
+  // received a close route message. Otherwise they would keep going back and
+  // forth.
+  if (close_routes_.find(pipe_id) != close_routes_.end()) {
+    close_routes_.erase(pipe_id);
+  } else if (channel_) {
+    // Default route id of 0 to reach the other side's RoutedRawChannel.
+    char message_data[sizeof(char) + sizeof(uint64_t)];
+    message_data[0] = ROUTE_CLOSED;
+    memcpy(&message_data[1], &pipe_id, sizeof(uint64_t));
+    scoped_ptr<MessageInTransit> message(new MessageInTransit(
+        MessageInTransit::Type::MESSAGE, arraysize(message_data),
+          message_data));
+    message->set_route_id(kInternalRoutingId);
+    channel_->WriteMessage(message.Pass());
+  }
+
+  if (!channel_ && routes_.empty()) {
+    // PostTask to avoid reentrancy since the broker might be calling us.
+    base::MessageLoop::current()->DeleteSoon(FROM_HERE, this);
+  }
+}
+
+RoutedRawChannel::~RoutedRawChannel() {
+  destruct_callback_.Run(this);
+}
+
+void RoutedRawChannel::OnReadMessage(
+    const MessageInTransit::View& message_view,
+    ScopedPlatformHandleVectorPtr platform_handles) {
+  DCHECK(internal::g_io_thread_task_runner->RunsTasksOnCurrentThread());
+  // Note: normally, when a message arrives here we should find a corresponding
+  // entry for the MessagePipeDispatcher with the given route_id. However it is
+  // possible that they just connected, and due to race conditions one side has
+  // connected and sent a message (and even closed) before the other side had a
+  // chance to register with this RoutedRawChannel. In that case, we must buffer
+  // all messages.
+  base::AutoLock auto_lock(lock_);
+  uint64_t route_id = message_view.route_id();
+  if (route_id == kInternalRoutingId) {
+    CHECK_EQ(message_view.num_bytes(), sizeof(char) + sizeof(uint64_t));
+    const char* bytes = static_cast<const char*>(message_view.bytes());
+    CHECK_EQ(bytes[0], ROUTE_CLOSED);
+    uint64_t closed_route = *reinterpret_cast<const uint64_t*>(&bytes[1]);
+    if (close_routes_.find(closed_route) != close_routes_.end()) {
+      NOTREACHED() << "Should only receive one ROUTE_CLOSED per route.";
+      return;
+    }
+    close_routes_.insert(closed_route);
+    if (routes_.find(closed_route) == routes_.end())
+      return;  // This side hasn't connected yet.
+
+    routes_[closed_route]->OnError(ERROR_READ_SHUTDOWN);
+    return;
+  }
+
+  if (routes_.find(route_id) != routes_.end()) {
+    routes_[route_id]->OnReadMessage(message_view, platform_handles.Pass());
+  } else {
+    scoped_ptr<PendingMessage> msg(new PendingMessage);
+    msg->message.resize(message_view.total_size());
+    memcpy(&msg->message[0], message_view.main_buffer(),
+           message_view.total_size());
+    msg->handles = platform_handles.Pass();
+    pending_messages_.push_back(msg.Pass());
+  }
+}
+
+void RoutedRawChannel::OnError(Error error) {
+  DCHECK(internal::g_io_thread_task_runner->RunsTasksOnCurrentThread());
+  bool destruct = false;
+  {
+    base::AutoLock auto_lock(lock_);
+
+    channel_->Shutdown();
+    channel_ = nullptr;
+    if (routes_.empty()) {
+      destruct = true;
+    } else {
+      for (auto it = routes_.begin(); it != routes_.end(); ++it)
+        it->second->OnError(error);
+    }
+  }
+
+  if (destruct)
+    delete this;
+}
+
+}  // namespace edk
+}  // namespace mojo