Mojo: First stab at making MessagePipes work across OS pipes.

mojo/system/channel.cc

+// Copyright 2013 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/system/channel.h"
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+#include "base/message_loop/message_loop.h"
+#include "base/strings/stringprintf.h"
+
+namespace mojo {
+namespace system {
+
+COMPILE_ASSERT(Channel::kBootstrapEndpointId !=
+                   MessageInTransit::kInvalidEndpointId,
+               kBootstrapEndpointId_is_invalid);
+
+STATIC_CONST_MEMBER_DEFINITION const MessageInTransit::EndpointId
+    Channel::kBootstrapEndpointId;
+
+Channel::EndpointInfo::EndpointInfo() {
+}
+
+Channel::EndpointInfo::EndpointInfo(scoped_refptr<MessagePipe> message_pipe,
+                                    unsigned port)
+    : message_pipe(message_pipe),
+      port(port) {
+}
+
+Channel::EndpointInfo::~EndpointInfo() {
+}
+
+Channel::Channel()
+    : next_local_id_(kBootstrapEndpointId) {
+}
+
+bool Channel::Init(const PlatformChannelHandle& handle) {
+  DCHECK(creation_thread_checker_.CalledOnValidThread());
+
+  // No need to take |lock_|, since this must be called before this object
+  // becomes thread-safe.
+  DCHECK(!raw_channel_.get());
+
+  raw_channel_.reset(
+      RawChannel::Create(handle, this, base::MessageLoop::current()));
+  if (!raw_channel_->Init()) {
+    raw_channel_.reset();
+    return false;
+  }
+
+  return true;
+}
+
+void Channel::Shutdown() {
+  DCHECK(creation_thread_checker_.CalledOnValidThread());
+
+  base::AutoLock locker(lock_);
+  DCHECK(raw_channel_.get());
+  raw_channel_->Shutdown();
+  raw_channel_.reset();
+
+  // TODO(vtl): Should I clear |local_id_to_endpoint_info_map_|? Or assert that
+  // it's empty?
+}
+
+MessageInTransit::EndpointId Channel::AttachMessagePipeEndpoint(
+    scoped_refptr<MessagePipe> message_pipe, unsigned port) {
+  MessageInTransit::EndpointId local_id;
+  {
+    base::AutoLock locker(lock_);
+
+    while (next_local_id_ == MessageInTransit::kInvalidEndpointId ||
+           local_id_to_endpoint_info_map_.find(next_local_id_) !=
+               local_id_to_endpoint_info_map_.end())
+      next_local_id_++;
+
+    local_id = next_local_id_;
+    next_local_id_++;
+
+    // TODO(vtl): Use emplace when we move to C++11 unordered_maps. (It'll avoid
+    // some expensive reference count increment/decrements.) Once this is done,
+    // we should be able to delete |EndpointInfo|'s default constructor.
+    local_id_to_endpoint_info_map_[local_id] = EndpointInfo(message_pipe, port);
+  }
+
+  message_pipe->Attach(port, scoped_refptr<Channel>(this), local_id);
+  return local_id;
+}
+
+void Channel::RunMessagePipeEndpoint(MessageInTransit::EndpointId local_id,
+                                     MessageInTransit::EndpointId remote_id) {
+  EndpointInfo endpoint_info;
+  {
+    base::AutoLock locker(lock_);
+
+    IdToEndpointInfoMap::const_iterator it =
+        local_id_to_endpoint_info_map_.find(local_id);
+    CHECK(it != local_id_to_endpoint_info_map_.end());
+    endpoint_info = it->second;
+  }
+
+  endpoint_info.message_pipe->Run(endpoint_info.port, remote_id);
+}
+
+bool Channel::WriteMessage(MessageInTransit* message) {
+  base::AutoLock locker(lock_);
+  if (!raw_channel_.get()) {
+    // TODO(vtl): I think this is probably not an error condition, but I should
+    // think about it (and the shutdown sequence) more carefully.
+    LOG(INFO) << "WriteMessage() after shutdown";
+    return false;
+  }
+
+  return raw_channel_->WriteMessage(message);
+}
+
+void Channel::DetachMessagePipeEndpoint(MessageInTransit::EndpointId local_id) {
+  DCHECK_NE(local_id, MessageInTransit::kInvalidEndpointId);
+
+  base::AutoLock locker_(lock_);
+  local_id_to_endpoint_info_map_.erase(local_id);
+}
+
+Channel::~Channel() {
+  // The channel should have been shut down first.
+  DCHECK(!raw_channel_.get());
+}
+
+void Channel::OnReadMessage(const MessageInTransit& message) {
+  switch (message.type()) {
+    case MessageInTransit::kTypeMessagePipeEndpoint:
+    case MessageInTransit::kTypeMessagePipe:
+      OnReadMessageForDownstream(message);
+      break;
+    case MessageInTransit::TYPE_CHANNEL:
+      OnReadMessageForChannel(message);
+      break;
+    default:
+      HandleRemoteError(base::StringPrintf(
+          "Received message of invalid type %u",
+          static_cast<unsigned>(message.type())));
+      break;
+  }
+}
+
+void Channel::OnFatalError(FatalError fatal_error) {
+  // TODO(vtl): IMPORTANT. Notify all our endpoints that they're dead.
+  NOTIMPLEMENTED();
+}
+
+void Channel::OnReadMessageForDownstream(const MessageInTransit& message) {
+  DCHECK(message.type() == MessageInTransit::kTypeMessagePipeEndpoint ||
+         message.type() == MessageInTransit::kTypeMessagePipe);
+
+  MessageInTransit::EndpointId local_id = message.destination_id();
+  if (local_id == MessageInTransit::kInvalidEndpointId) {
+    HandleRemoteError("Received message with no destination ID");
+    return;
+  }
+
+  EndpointInfo endpoint_info;
+  {
+    base::AutoLock locker(lock_);
+
+    // Since we own |raw_channel_|, and this method and |Shutdown()| should only
+    // be called from the creation thread, |raw_channel_| should never be null
+    // here.
+    DCHECK(raw_channel_.get());
+
+    IdToEndpointInfoMap::const_iterator it =
+        local_id_to_endpoint_info_map_.find(local_id);
+    if (it == local_id_to_endpoint_info_map_.end()) {
+      HandleRemoteError(base::StringPrintf(
+          "Received a message for nonexistent local destination ID %u",
+          static_cast<unsigned>(local_id)));
+      return;
+    }
+    endpoint_info = it->second;
+  }
+
+  // We need to duplicate the message, because |EnqueueMessage()| will take
+  // ownership of it.
+  MessageInTransit* own_message = MessageInTransit::Create(
+      message.type(), message.subtype(), message.data(), message.data_size());
+  if (endpoint_info.message_pipe->EnqueueMessage(
+          MessagePipe::GetPeerPort(endpoint_info.port),
+          own_message) != MOJO_RESULT_OK) {
+    HandleLocalError(base::StringPrintf(
+        "Failed to enqueue message to local destination ID %u",
+        static_cast<unsigned>(local_id)));
+    return;
+  }
+}
+
+void Channel::OnReadMessageForChannel(const MessageInTransit& message) {
+  // TODO(vtl): Currently no channel-only messages yet.
+  HandleRemoteError("Received invalid channel message");
+  NOTREACHED();
+}
+
+void Channel::HandleRemoteError(const base::StringPiece& error_message) {
+  // TODO(vtl): Is this how we really want to handle this?
+  LOG(INFO) << error_message;
+}
+
+void Channel::HandleLocalError(const base::StringPiece& error_message) {
+  // TODO(vtl): Is this how we really want to handle this?
+  LOG(FATAL) << error_message;
+}
+
+}  // namespace system
+}  // namespace mojo