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 bool ExportedObject::UnexportMethodAndBlock(const std::string& interface_name,
  72                                             const std::string& method_name) {
  73   bus_->AssertOnDBusThread();
  74
  75   const std::string absolute_method_name =
  76       GetAbsoluteMemberName(interface_name, method_name);
  77   MethodTable::const_iterator iter = method_table_.find(absolute_method_name);
  78   if (iter == method_table_.end()) {
  79     LOG(ERROR) << absolute_method_name << " is not exported";
  80     return false;
  81   }
  82
  83   method_table_.erase(iter);
  84
  85   return true;
  86 }
  87
  88 void ExportedObject::ExportMethod(const std::string& interface_name,
  89                                   const std::string& method_name,
  90                                   MethodCallCallback method_call_callback,
  91                                   OnExportedCallback on_exported_calback) {
  92   bus_->AssertOnOriginThread();
  93
  94   base::Closure task = base::Bind(&ExportedObject::ExportMethodInternal,
  95                                   this,
  96                                   interface_name,
  97                                   method_name,
  98                                   method_call_callback,
  99                                   on_exported_calback);
 100   bus_->GetDBusTaskRunner()->PostTask(FROM_HERE, task);
 101 }
 102
 103 void ExportedObject::UnexportMethod(
 104     const std::string& interface_name,
 105     const std::string& method_name,
 106     OnUnexportedCallback on_unexported_calback) {
 107   bus_->AssertOnOriginThread();
 108
 109   base::Closure task =
 110       base::Bind(&ExportedObject::UnexportMethodInternal, this, interface_name,
 111                  method_name, on_unexported_calback);
 112   bus_->GetDBusTaskRunner()->PostTask(FROM_HERE, task);
 113 }
 114
 115 void ExportedObject::SendSignal(Signal* signal) {
 116   // For signals, the object path should be set to the path to the sender
 117   // object, which is this exported object here.
 118   CHECK(signal->SetPath(object_path_));
 119
 120   // Increment the reference count so we can safely reference the
 121   // underlying signal message until the signal sending is complete. This
 122   // will be unref'ed in SendSignalInternal().
 123   DBusMessage* signal_message = signal->raw_message();
 124   dbus_message_ref(signal_message);
 125
 126   const base::TimeTicks start_time = base::TimeTicks::Now();
 127   if (bus_->GetDBusTaskRunner()->RunsTasksInCurrentSequence()) {
 128     // The Chrome OS power manager doesn't use a dedicated TaskRunner for
 129     // sending DBus messages.  Sending signals asynchronously can cause an
 130     // inversion in the message order if the power manager calls
 131     // ObjectProxy::CallMethodAndBlock() before going back to the top level of
 132     // the MessageLoop: crbug.com/472361.
 133     SendSignalInternal(start_time, signal_message);
 134   } else {
 135     bus_->GetDBusTaskRunner()->PostTask(
 136         FROM_HERE, base::BindOnce(&ExportedObject::SendSignalInternal, this,
 137                                   start_time, signal_message));
 138   }
 139 }
 140
 141 void ExportedObject::Unregister() {
 142   bus_->AssertOnDBusThread();
 143
 144   if (!object_is_registered_)
 145     return;
 146
 147   bus_->UnregisterObjectPath(object_path_);
 148   object_is_registered_ = false;
 149 }
 150
 151 void ExportedObject::ExportMethodInternal(
 152     const std::string& interface_name,
 153     const std::string& method_name,
 154     MethodCallCallback method_call_callback,
 155     OnExportedCallback on_exported_calback) {
 156   bus_->AssertOnDBusThread();
 157
 158   const bool success = ExportMethodAndBlock(interface_name,
 159                                             method_name,
 160                                             method_call_callback);
 161   bus_->GetOriginTaskRunner()->PostTask(
 162       FROM_HERE,
 163       base::BindOnce(&ExportedObject::OnExported, this, on_exported_calback,
 164                      interface_name, method_name, success));
 165 }
 166
 167 void ExportedObject::UnexportMethodInternal(
 168     const std::string& interface_name,
 169     const std::string& method_name,
 170     OnUnexportedCallback on_unexported_calback) {
 171   bus_->AssertOnDBusThread();
 172
 173   const bool success = UnexportMethodAndBlock(interface_name, method_name);
 174   bus_->GetOriginTaskRunner()->PostTask(
 175       FROM_HERE,
 176       base::BindOnce(&ExportedObject::OnUnexported, this, on_unexported_calback,
 177                      interface_name, method_name, success));
 178 }
 179
 180 void ExportedObject::OnExported(OnExportedCallback on_exported_callback,
 181                                 const std::string& interface_name,
 182                                 const std::string& method_name,
 183                                 bool success) {
 184   bus_->AssertOnOriginThread();
 185
 186   on_exported_callback.Run(interface_name, method_name, success);
 187 }
 188
 189 void ExportedObject::OnUnexported(OnExportedCallback on_unexported_callback,
 190                                   const std::string& interface_name,
 191                                   const std::string& method_name,
 192                                   bool success) {
 193   bus_->AssertOnOriginThread();
 194
 195   on_unexported_callback.Run(interface_name, method_name, success);
 196 }
 197
 198 void ExportedObject::SendSignalInternal(base::TimeTicks start_time,
 199                                         DBusMessage* signal_message) {
 200   uint32_t serial = 0;
 201   bus_->Send(signal_message, &serial);
 202   dbus_message_unref(signal_message);
 203   // Record time spent to send the the signal. This is not accurate as the
 204   // signal will actually be sent from the next run of the message loop,
 205   // but we can at least tell the number of signals sent.
 206   UMA_HISTOGRAM_TIMES("DBus.SignalSendTime",
 207                       base::TimeTicks::Now() - start_time);
 208 }
 209
 210 bool ExportedObject::Register() {
 211   bus_->AssertOnDBusThread();
 212
 213   if (object_is_registered_)
 214     return true;
 215
 216   ScopedDBusError error;
 217
 218   DBusObjectPathVTable vtable = {};
 219   vtable.message_function = &ExportedObject::HandleMessageThunk;
 220   vtable.unregister_function = &ExportedObject::OnUnregisteredThunk;
 221   const bool success = bus_->TryRegisterObjectPath(object_path_,
 222                                                    &vtable,
 223                                                    this,
 224                                                    error.get());
 225   if (!success) {
 226     LOG(ERROR) << "Failed to register the object: " << object_path_.value()
 227                << ": " << (error.is_set() ? error.message() : "");
 228     return false;
 229   }
 230
 231   object_is_registered_ = true;
 232   return true;
 233 }
 234
 235 DBusHandlerResult ExportedObject::HandleMessage(
 236     DBusConnection* connection,
 237     DBusMessage* raw_message) {
 238   bus_->AssertOnDBusThread();
 239   // ExportedObject only handles method calls. Ignore other message types (e.g.
 240   // signal).
 241   if (dbus_message_get_type(raw_message) != DBUS_MESSAGE_TYPE_METHOD_CALL)
 242     return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 243
 244   // raw_message will be unrefed on exit of the function. Increment the
 245   // reference so we can use it in MethodCall.
 246   dbus_message_ref(raw_message);
 247   std::unique_ptr<MethodCall> method_call(
 248       MethodCall::FromRawMessage(raw_message));
 249   const std::string interface = method_call->GetInterface();
 250   const std::string member = method_call->GetMember();
 251
 252   if (interface.empty()) {
 253     // We don't support method calls without interface.
 254     LOG(WARNING) << "Interface is missing: " << method_call->ToString();
 255     return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 256   }
 257
 258   // Check if we know about the method.
 259   const std::string absolute_method_name = GetAbsoluteMemberName(
 260       interface, member);
 261   MethodTable::const_iterator iter = method_table_.find(absolute_method_name);
 262   if (iter == method_table_.end()) {
 263     // Don't know about the method.
 264     LOG(WARNING) << "Unknown method: " << method_call->ToString();
 265     return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 266   }
 267
 268   const base::TimeTicks start_time = base::TimeTicks::Now();
 269   if (bus_->HasDBusThread()) {
 270     // Post a task to run the method in the origin thread.
 271     bus_->GetOriginTaskRunner()->PostTask(
 272         FROM_HERE,
 273         base::BindOnce(&ExportedObject::RunMethod, this, iter->second,
 274                        std::move(method_call), start_time));
 275   } else {
 276     // If the D-Bus thread is not used, just call the method directly.
 277     MethodCall* method = method_call.get();
 278     iter->second.Run(method,
 279                      base::Bind(&ExportedObject::SendResponse,
 280                                 this,
 281                                 start_time,
 282                                 base::Passed(&method_call)));
 283   }
 284
 285   // It's valid to say HANDLED here, and send a method response at a later
 286   // time from OnMethodCompleted() asynchronously.
 287   return DBUS_HANDLER_RESULT_HANDLED;
 288 }
 289
 290 void ExportedObject::RunMethod(MethodCallCallback method_call_callback,
 291                                std::unique_ptr<MethodCall> method_call,
 292                                base::TimeTicks start_time) {
 293   bus_->AssertOnOriginThread();
 294   MethodCall* method = method_call.get();
 295   method_call_callback.Run(method,
 296                            base::Bind(&ExportedObject::SendResponse,
 297                                       this,
 298                                       start_time,
 299                                       base::Passed(&method_call)));
 300 }
 301
 302 void ExportedObject::SendResponse(base::TimeTicks start_time,
 303                                   std::unique_ptr<MethodCall> method_call,
 304                                   std::unique_ptr<Response> response) {
 305   DCHECK(method_call);
 306   if (bus_->HasDBusThread()) {
 307     bus_->GetDBusTaskRunner()->PostTask(
 308         FROM_HERE, base::BindOnce(&ExportedObject::OnMethodCompleted, this,
 309                                   std::move(method_call), std::move(response),
 310                                   start_time));
 311   } else {
 312     OnMethodCompleted(std::move(method_call), std::move(response), start_time);
 313   }
 314 }
 315
 316 void ExportedObject::OnMethodCompleted(std::unique_ptr<MethodCall> method_call,
 317                                        std::unique_ptr<Response> response,
 318                                        base::TimeTicks start_time) {
 319   bus_->AssertOnDBusThread();
 320
 321   // Record if the method call is successful, or not. 1 if successful.
 322   UMA_HISTOGRAM_ENUMERATION("DBus.ExportedMethodHandleSuccess",
 323                             response ? 1 : 0,
 324                             kSuccessRatioHistogramMaxValue);
 325
 326   // Check if the bus is still connected. If the method takes long to
 327   // complete, the bus may be shut down meanwhile.
 328   if (!bus_->IsConnected())
 329     return;
 330
 331   if (!response) {
 332     // Something bad happened in the method call.
 333     std::unique_ptr<ErrorResponse> error_response(ErrorResponse::FromMethodCall(
 334         method_call.get(), DBUS_ERROR_FAILED,
 335         "error occurred in " + method_call->GetMember()));
 336     bus_->Send(error_response->raw_message(), nullptr);
 337     return;
 338   }
 339
 340   // The method call was successful.
 341   bus_->Send(response->raw_message(), nullptr);
 342
 343   // Record time spent to handle the the method call. Don't include failures.
 344   UMA_HISTOGRAM_TIMES("DBus.ExportedMethodHandleTime",
 345                       base::TimeTicks::Now() - start_time);
 346 }
 347
 348 void ExportedObject::OnUnregistered(DBusConnection* connection) {
 349 }
 350
 351 DBusHandlerResult ExportedObject::HandleMessageThunk(
 352     DBusConnection* connection,
 353     DBusMessage* raw_message,
 354     void* user_data) {
 355   ExportedObject* self = reinterpret_cast<ExportedObject*>(user_data);
 356   return self->HandleMessage(connection, raw_message);
 357 }
 358
 359 void ExportedObject::OnUnregisteredThunk(DBusConnection *connection,
 360                                          void* user_data) {
 361   ExportedObject* self = reinterpret_cast<ExportedObject*>(user_data);
 362   return self->OnUnregistered(connection);
 363 }
 364
 365 }  // namespace dbus