Implement Bus and ObjectProxy classes for our D-Bus library.

dbus/object_proxy.cc

+// Copyright (c) 2011 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 "dbus/bus.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/message_loop.h"
+#include "base/threading/thread.h"
+#include "base/threading/thread_restrictions.h"
+#include "dbus/error.h"
+#include "dbus/message.h"
+#include "dbus/object_proxy.h"
+
+namespace dbus {
+
+ObjectProxy::ObjectProxy(Bus* bus,
+                         const std::string& service_name,
+                         const std::string& object_path)
+    : bus_(bus),
+      service_name_(service_name),
+      object_path_(object_path) {
+}
+
+ObjectProxy::~ObjectProxy() {
+}
+
+// Originally we tried to make |method_call| a const reference, but we
+// gave up as dbus_connection_send_with_reply_and_block() takes a
+// non-const pointer of DBusMessage as the second parameter.
+bool ObjectProxy::CallMethodAndBlock(MethodCall* method_call,
+                                     int timeout_ms,
+                                     Response* response) {
+  bus_->AssertOnDBusThread();
+
+  if (!bus_->Connect())
+    return false;
+
+  method_call->SetDestination(service_name_);
+  method_call->SetPath(object_path_);
+  DBusMessage* request_message = method_call->raw_message();
+
+  ScopedDBusError error;
+
+  // Send the message synchronously.
+  DBusMessage* response_message =
+      bus_->SendWithReplyAndBlock(request_message, timeout_ms, error.get());
+
+  if (!response_message) {
+    LOG(ERROR) << "Failed to call method: "
+               << (error.is_set() ? error.message() : "");
+    return false;
+  }
+  response->reset_raw_message(response_message);
+
+  return true;
+}
+
+void ObjectProxy::CallMethod(MethodCall* method_call,
+                             int timeout_ms,
+                             ResponseCallback callback) {
+  bus_->AssertOnOriginThread();
+
+  method_call->SetDestination(service_name_);
+  method_call->SetPath(object_path_);
+  // Increment the reference count so we can safely reference the
+  // underlying request message until the method call is complete. This
+  // will be unref'ed in StartAsyncMethodCall().
+  DBusMessage* request_message = method_call->raw_message();
+  dbus_message_ref(request_message);
+
+  // Bind() won't compile if we pass request_message as-is since
+  // DBusMessage is an opaque struct which Bind() cannot handle.
+  // Hence we cast it to void* to workaround the issue.
+  base::Closure task = base::Bind(&ObjectProxy::StartAsyncMethodCall,
+                                  this,
+                                  timeout_ms,
+                                  static_cast<void*>(request_message),
+                                  callback);
+  // Wait for the response in the D-Bus thread.
+  bus_->PostTaskToDBusThread(FROM_HERE, task);
+}
+
+ObjectProxy::OnPendingCallIsCompleteData::OnPendingCallIsCompleteData(
+    ObjectProxy* in_object_proxy,
+    ResponseCallback in_response_callback)
+    : object_proxy(in_object_proxy),
+      response_callback(in_response_callback) {
+}
+
+ObjectProxy::OnPendingCallIsCompleteData::~OnPendingCallIsCompleteData() {
+}
+
+void ObjectProxy::StartAsyncMethodCall(int timeout_ms,
+                                       void* in_request_message,
+                                       ResponseCallback response_callback) {
+  bus_->AssertOnDBusThread();
+
+  if (!bus_->Connect() || !bus_->SetUpAsyncOperations()) {

[stevenjb, 2011/08/15 21:42:04]

Comment describing this case? Is this an error? Is the NULL response the failure
indicator?

[satorux1, 2011/08/16 22:25:37]

Yes. Added a comment about it.

+    Response* response = NULL;
+    base::Closure task = base::Bind(&ObjectProxy::RunResponseCallback,
+                                    this,
+                                    response_callback,
+                                    response);
+    bus_->PostTaskToOriginThread(FROM_HERE, task);
+    return;
+  }
+
+  DBusMessage* request_message =
+      static_cast<DBusMessage*>(in_request_message);
+  DBusPendingCall* pending_call = NULL;
+
+  bus_->SendWithReply(request_message, &pending_call, timeout_ms);
+
+  // Prepare the data we'll be passing to OnPendingCallIsCompleteThunk().
+  // The data will be deleted in OnPendingCallIsCompleteThunk().
+  OnPendingCallIsCompleteData* data =
+      new OnPendingCallIsCompleteData(this, response_callback);
+
+  // This returns false only when unable to allocate memory.
+  const bool success = dbus_pending_call_set_notify(
+      pending_call,
+      &ObjectProxy::OnPendingCallIsCompleteThunk,
+      data,
+      NULL);
+  CHECK(success) << "Unable to allocate memory";
+  dbus_pending_call_unref(pending_call);
+
+  // It's now safe to unref the request message.
+  dbus_message_unref(request_message);
+}
+
+void ObjectProxy::OnPendingCallIsComplete(DBusPendingCall* pending_call,
+                                          ResponseCallback response_callback) {
+  bus_->AssertOnDBusThread();
+
+  DBusMessage* response_message = dbus_pending_call_steal_reply(pending_call);
+
+  if (!response_message) {
+    // This shouldn't happen but just in case.
+    LOG(ERROR) << "The response message is not received for some reason";
+    Response* response = NULL;
+    base::Closure task = base::Bind(&ObjectProxy::RunResponseCallback,
+                                    this,
+                                    response_callback,
+                                    response);
+    bus_->PostTaskToOriginThread(FROM_HERE, task);
+    return;
+  }
+
+  // The response message will be deleted in RunResponseCallback().
+  Response* response = new Response;
+  response->reset_raw_message(response_message);
+  base::Closure task = base::Bind(&ObjectProxy::RunResponseCallback,
+                                  this,
+                                  response_callback,
+                                  response);
+  bus_->PostTaskToOriginThread(FROM_HERE, task);
+}
+
+void ObjectProxy::RunResponseCallback(ResponseCallback response_callback,
+                                      Response* response) {
+  bus_->AssertOnOriginThread();
+
+  if (!response) {
+    // The response is not received.
+    response_callback.Run(NULL);
+  } else if (response->GetMessageType() == Message::MESSAGE_ERROR) {
+    // Error message may contain the error message as string.
+    dbus::MessageReader reader(response);
+    std::string error_message;
+    reader.PopString(&error_message);
+    LOG(ERROR) << "Failed to call method: " << response->GetErrorName()
+               << ": " << error_message;
+    // We don't give the error message to the callback.
+    response_callback.Run(NULL);
+  } else {
+    // The response is successfuly received.
+    response_callback.Run(response);
+  }
+  delete response;  // It's ok to delete NULL.
+}
+
+void ObjectProxy::OnPendingCallIsCompleteThunk(DBusPendingCall* pending_call,
+                                               void* user_data) {
+  OnPendingCallIsCompleteData* data =
+      reinterpret_cast<OnPendingCallIsCompleteData*>(user_data);
+  ObjectProxy* self = data->object_proxy;
+  self->OnPendingCallIsComplete(pending_call,
+                                data->response_callback);
+  delete data;
+}
+
+}  // namespace dbus