dbus/exported_object.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "dbus/exported_object.h"
   6
   7 #include <stdint.h>
   8 #include <utility>
   9
  10 #include "base/bind.h"
  11 #include "base/logging.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/metrics/histogram_macros.h"
  14 #include "base/task_runner.h"
  15 #include "base/threading/thread_restrictions.h"
  16 #include "base/time/time.h"
  17 #include "dbus/bus.h"
  18 #include "dbus/message.h"
  19 #include "dbus/object_path.h"
  20 #include "dbus/scoped_dbus_error.h"
  21 #include "dbus/util.h"
  22
  23 namespace dbus {
  24
  25 namespace {
  26
  27 // Used for success ratio histograms. 1 for success, 0 for failure.
  28 const int kSuccessRatioHistogramMaxValue = 2;
  29
  30 }  // namespace
  31
  32 ExportedObject::ExportedObject(Bus* bus,
  33                                const ObjectPath& object_path)
  34     : bus_(bus),
  35       object_path_(object_path),
  36       object_is_registered_(false) {
  37   LOG_IF(FATAL, !object_path_.IsValid()) << object_path_.value();
  38 }
  39
  40 ExportedObject::~ExportedObject() {
  41   DCHECK(!object_is_registered_);
  42 }
  43
  44 bool ExportedObject::ExportMethodAndBlock(
  45     const std::string& interface_name,
  46     const std::string& method_name,
  47     MethodCallCallback method_call_callback) {
  48   bus_->AssertOnDBusThread();
  49
  50   // Check if the method is already exported.
  51   const std::string absolute_method_name =
  52       GetAbsoluteMemberName(interface_name, method_name);
  53   if (method_table_.find(absolute_method_name) != method_table_.end()) {
  54     LOG(ERROR) << absolute_method_name << " is already exported";
  55     return false;
  56   }
  57
  58   if (!bus_->Connect())
  59     return false;
  60   if (!bus_->SetUpAsyncOperations())
  61     return false;
  62   if (!Register())
  63     return false;
  64
  65   // Add the method callback to the method table.
  66   method_table_[absolute_method_name] = method_call_callback;
  67
  68   return true;
  69 }
  70
  71 void ExportedObject::ExportMethod(const std::string& interface_name,
  72                                   const std::string& method_name,
  73                                   MethodCallCallback method_call_callback,
  74                                   OnExportedCallback on_exported_calback) {
  75   bus_->AssertOnOriginThread();
  76
  77   base::Closure task = base::Bind(&ExportedObject::ExportMethodInternal,
  78                                   this,
  79                                   interface_name,
  80                                   method_name,
  81                                   method_call_callback,
  82                                   on_exported_calback);
  83   bus_->GetDBusTaskRunner()->PostTask(FROM_HERE, task);
  84 }
  85
  86 void ExportedObject::SendSignal(Signal* signal) {
  87   // For signals, the object path should be set to the path to the sender
  88   // object, which is this exported object here.
  89   CHECK(signal->SetPath(object_path_));
  90
  91   // Increment the reference count so we can safely reference the
  92   // underlying signal message until the signal sending is complete. This
  93   // will be unref'ed in SendSignalInternal().
  94   DBusMessage* signal_message = signal->raw_message();
  95   dbus_message_ref(signal_message);
  96
  97   const base::TimeTicks start_time = base::TimeTicks::Now();
  98   if (bus_->GetDBusTaskRunner()->RunsTasksInCurrentSequence()) {
  99     // The Chrome OS power manager doesn't use a dedicated TaskRunner for
 100     // sending DBus messages.  Sending signals asynchronously can cause an
 101     // inversion in the message order if the power manager calls
 102     // ObjectProxy::CallMethodAndBlock() before going back to the top level of
 103     // the MessageLoop: crbug.com/472361.
 104     SendSignalInternal(start_time, signal_message);
 105   } else {
 106     bus_->GetDBusTaskRunner()->PostTask(
 107         FROM_HERE,
 108         base::Bind(&ExportedObject::SendSignalInternal,
 109                    this,
 110                    start_time,
 111                    signal_message));
 112   }
 113 }
 114
 115 void ExportedObject::Unregister() {
 116   bus_->AssertOnDBusThread();
 117
 118   if (!object_is_registered_)
 119     return;
 120
 121   bus_->UnregisterObjectPath(object_path_);
 122   object_is_registered_ = false;
 123 }
 124
 125 void ExportedObject::ExportMethodInternal(
 126     const std::string& interface_name,
 127     const std::string& method_name,
 128     MethodCallCallback method_call_callback,
 129     OnExportedCallback on_exported_calback) {
 130   bus_->AssertOnDBusThread();
 131
 132   const bool success = ExportMethodAndBlock(interface_name,
 133                                             method_name,
 134                                             method_call_callback);
 135   bus_->GetOriginTaskRunner()->PostTask(FROM_HERE,
 136                                         base::Bind(&ExportedObject::OnExported,
 137                                                    this,
 138                                                    on_exported_calback,
 139                                                    interface_name,
 140                                                    method_name,
 141                                                    success));
 142 }
 143
 144 void ExportedObject::OnExported(OnExportedCallback on_exported_callback,
 145                                 const std::string& interface_name,
 146                                 const std::string& method_name,
 147                                 bool success) {
 148   bus_->AssertOnOriginThread();
 149
 150   on_exported_callback.Run(interface_name, method_name, success);
 151 }
 152
 153 void ExportedObject::SendSignalInternal(base::TimeTicks start_time,
 154                                         DBusMessage* signal_message) {
 155   uint32_t serial = 0;
 156   bus_->Send(signal_message, &serial);
 157   dbus_message_unref(signal_message);
 158   // Record time spent to send the the signal. This is not accurate as the
 159   // signal will actually be sent from the next run of the message loop,
 160   // but we can at least tell the number of signals sent.
 161   UMA_HISTOGRAM_TIMES("DBus.SignalSendTime",
 162                       base::TimeTicks::Now() - start_time);
 163 }
 164
 165 bool ExportedObject::Register() {
 166   bus_->AssertOnDBusThread();
 167
 168   if (object_is_registered_)
 169     return true;
 170
 171   ScopedDBusError error;
 172
 173   DBusObjectPathVTable vtable = {};
 174   vtable.message_function = &ExportedObject::HandleMessageThunk;
 175   vtable.unregister_function = &ExportedObject::OnUnregisteredThunk;
 176   const bool success = bus_->TryRegisterObjectPath(object_path_,
 177                                                    &vtable,
 178                                                    this,
 179                                                    error.get());
 180   if (!success) {
 181     LOG(ERROR) << "Failed to register the object: " << object_path_.value()
 182                << ": " << (error.is_set() ? error.message() : "");
 183     return false;
 184   }
 185
 186   object_is_registered_ = true;
 187   return true;
 188 }
 189
 190 DBusHandlerResult ExportedObject::HandleMessage(
 191     DBusConnection* connection,
 192     DBusMessage* raw_message) {
 193   bus_->AssertOnDBusThread();
 194   // ExportedObject only handles method calls. Ignore other message types (e.g.
 195   // signal).
 196   if (dbus_message_get_type(raw_message) != DBUS_MESSAGE_TYPE_METHOD_CALL)
 197     return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 198
 199   // raw_message will be unrefed on exit of the function. Increment the
 200   // reference so we can use it in MethodCall.
 201   dbus_message_ref(raw_message);
 202   std::unique_ptr<MethodCall> method_call(
 203       MethodCall::FromRawMessage(raw_message));
 204   const std::string interface = method_call->GetInterface();
 205   const std::string member = method_call->GetMember();
 206
 207   if (interface.empty()) {
 208     // We don't support method calls without interface.
 209     LOG(WARNING) << "Interface is missing: " << method_call->ToString();
 210     return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 211   }
 212
 213   // Check if we know about the method.
 214   const std::string absolute_method_name = GetAbsoluteMemberName(
 215       interface, member);
 216   MethodTable::const_iterator iter = method_table_.find(absolute_method_name);
 217   if (iter == method_table_.end()) {
 218     // Don't know about the method.
 219     LOG(WARNING) << "Unknown method: " << method_call->ToString();
 220     return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 221   }
 222
 223   const base::TimeTicks start_time = base::TimeTicks::Now();
 224   if (bus_->HasDBusThread()) {
 225     // Post a task to run the method in the origin thread.
 226     bus_->GetOriginTaskRunner()->PostTask(
 227         FROM_HERE,
 228         base::BindOnce(&ExportedObject::RunMethod, this, iter->second,
 229                        std::move(method_call), start_time));
 230   } else {
 231     // If the D-Bus thread is not used, just call the method directly.
 232     MethodCall* method = method_call.get();
 233     iter->second.Run(method,
 234                      base::Bind(&ExportedObject::SendResponse,
 235                                 this,
 236                                 start_time,
 237                                 base::Passed(&method_call)));
 238   }
 239
 240   // It's valid to say HANDLED here, and send a method response at a later
 241   // time from OnMethodCompleted() asynchronously.
 242   return DBUS_HANDLER_RESULT_HANDLED;
 243 }
 244
 245 void ExportedObject::RunMethod(MethodCallCallback method_call_callback,
 246                                std::unique_ptr<MethodCall> method_call,
 247                                base::TimeTicks start_time) {
 248   bus_->AssertOnOriginThread();
 249   MethodCall* method = method_call.get();
 250   method_call_callback.Run(method,
 251                            base::Bind(&ExportedObject::SendResponse,
 252                                       this,
 253                                       start_time,
 254                                       base::Passed(&method_call)));
 255 }
 256
 257 void ExportedObject::SendResponse(base::TimeTicks start_time,
 258                                   std::unique_ptr<MethodCall> method_call,
 259                                   std::unique_ptr<Response> response) {
 260   DCHECK(method_call);
 261   if (bus_->HasDBusThread()) {
 262     bus_->GetDBusTaskRunner()->PostTask(
 263         FROM_HERE, base::BindOnce(&ExportedObject::OnMethodCompleted, this,
 264                                   std::move(method_call), std::move(response),
 265                                   start_time));
 266   } else {
 267     OnMethodCompleted(std::move(method_call), std::move(response), start_time);
 268   }
 269 }
 270
 271 void ExportedObject::OnMethodCompleted(std::unique_ptr<MethodCall> method_call,
 272                                        std::unique_ptr<Response> response,
 273                                        base::TimeTicks start_time) {
 274   bus_->AssertOnDBusThread();
 275
 276   // Record if the method call is successful, or not. 1 if successful.
 277   UMA_HISTOGRAM_ENUMERATION("DBus.ExportedMethodHandleSuccess",
 278                             response ? 1 : 0,
 279                             kSuccessRatioHistogramMaxValue);
 280
 281   // Check if the bus is still connected. If the method takes long to
 282   // complete, the bus may be shut down meanwhile.
 283   if (!bus_->IsConnected())
 284     return;
 285
 286   if (!response) {
 287     // Something bad happened in the method call.
 288     std::unique_ptr<ErrorResponse> error_response(ErrorResponse::FromMethodCall(
 289         method_call.get(), DBUS_ERROR_FAILED,
 290         "error occurred in " + method_call->GetMember()));
 291     bus_->Send(error_response->raw_message(), nullptr);
 292     return;
 293   }
 294
 295   // The method call was successful.
 296   bus_->Send(response->raw_message(), nullptr);
 297
 298   // Record time spent to handle the the method call. Don't include failures.
 299   UMA_HISTOGRAM_TIMES("DBus.ExportedMethodHandleTime",
 300                       base::TimeTicks::Now() - start_time);
 301 }
 302
 303 void ExportedObject::OnUnregistered(DBusConnection* connection) {
 304 }
 305
 306 DBusHandlerResult ExportedObject::HandleMessageThunk(
 307     DBusConnection* connection,
 308     DBusMessage* raw_message,
 309     void* user_data) {
 310   ExportedObject* self = reinterpret_cast<ExportedObject*>(user_data);
 311   return self->HandleMessage(connection, raw_message);
 312 }
 313
 314 void ExportedObject::OnUnregisteredThunk(DBusConnection *connection,
 315                                          void* user_data) {
 316   ExportedObject* self = reinterpret_cast<ExportedObject*>(user_data);
 317   return self->OnUnregistered(connection);
 318 }
 319
 320 }  // namespace dbus