keybuk@chromium.org | 7e0c493 | 2012-02-15 13:21:08 +0900 | [diff] [blame] | 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 | #ifndef DBUS_PROPERTY_H_ |
| 6 | #define DBUS_PROPERTY_H_ |
| 7 | #pragma once |
| 8 | |
| 9 | #include <map> |
| 10 | #include <string> |
| 11 | |
| 12 | #include "base/basictypes.h" |
| 13 | #include "base/bind.h" |
| 14 | #include "base/callback.h" |
| 15 | #include "dbus/message.h" |
| 16 | #include "dbus/object_proxy.h" |
| 17 | |
| 18 | // D-Bus objects frequently provide sets of properties accessed via a |
| 19 | // standard interface of method calls and signals to obtain the current value, |
| 20 | // set a new value and be notified of changes to the value. Unfortunately this |
| 21 | // interface makes heavy use of variants and dictionaries of variants. The |
| 22 | // classes defined here make dealing with properties in a type-safe manner |
| 23 | // possible. |
| 24 | // |
| 25 | // Client implementation classes should define a Properties structure, deriving |
| 26 | // from the PropertySet class defined here. This structure should contain a |
| 27 | // member for each property defined as an instance of the Property<> class, |
| 28 | // specifying the type to the template. Finally the structure should chain up |
| 29 | // to the PropertySet constructor, and then call RegisterProperty() for each |
| 30 | // property defined to associate them with their string name. |
| 31 | // |
| 32 | // Example: |
| 33 | // class ExampleClient { |
| 34 | // public: |
| 35 | // struct Properties : public dbus::PropertySet { |
| 36 | // dbus::Property<std::string> name; |
| 37 | // dbus::Property<uint16> version; |
| 38 | // dbus::Property<dbus::ObjectPath> parent; |
| 39 | // dbus::Property<std::vector<std::string> > children; |
| 40 | // |
| 41 | // Properties(dbus::ObjectProxy* object_proxy, |
| 42 | // PropertyChangedCallback callback) |
| 43 | // : dbus::PropertySet(object_proxy, kExampleInterface, callback) { |
| 44 | // RegisterProperty("Name", &name); |
| 45 | // RegisterProperty("Version", &version); |
| 46 | // RegisterProperty("Parent", &parent); |
| 47 | // RegisterProperty("Children", &children); |
| 48 | // } |
| 49 | // }; |
| 50 | // |
| 51 | // The Properties structure requires a pointer to the object proxy of the |
| 52 | // actual object to track, and after construction should have signals |
| 53 | // connected to that object and initial values set by calling ConnectSignals() |
| 54 | // and GetAll(). The structure should not outlive the object proxy, so it |
| 55 | // is recommended that the lifecycle of both be managed together. |
| 56 | // |
| 57 | // Example (continued): |
| 58 | // |
| 59 | // typedef std::map<std::pair<dbus::ObjectProxy*,Properties*> > Object; |
| 60 | // typedef std::map<dbus::ObjectPath,Object> ObjectMap; |
| 61 | // ObjectMap object_map_; |
| 62 | // |
| 63 | // dbus::ObjectProxy* GetObjectProxy(const dbus::ObjectPath& object_path) { |
| 64 | // return GetObject(object_path).first; |
| 65 | // } |
| 66 | // |
| 67 | // Properties* GetProperties(const dbus::ObjectPath& object_path) { |
| 68 | // return GetObject(object_path).second; |
| 69 | // } |
| 70 | // |
| 71 | // Object GetObject(const dbus::ObjectPath& object_path) { |
| 72 | // ObjectMap::iterator it = object_map_.find(object_path); |
| 73 | // if (it != object_map_.end()) |
| 74 | // return it->second; |
| 75 | // |
| 76 | // dbus::ObjectProxy* object_proxy = bus->GetObjectProxy(...); |
| 77 | // // connect signals, ect. |
| 78 | // |
| 79 | // Properties* properties = new Properties( |
| 80 | // object_proxy, |
| 81 | // base::Bind(&PropertyChanged, |
| 82 | // weak_ptr_factory_.GetWeakPtr(), |
| 83 | // object_path)); |
| 84 | // properties->ConnectSignals(); |
| 85 | // properties->GetAll(); |
| 86 | // |
| 87 | // return object_map_.insert(std::make_pair(object_proxy, |
| 88 | // properties).first; |
| 89 | // } |
| 90 | // }; |
| 91 | // |
| 92 | // This now allows code using the client implementation to access properties |
| 93 | // in a type-safe manner, and assuming the PropertyChanged callback is |
| 94 | // propogated up to observers, be notified of changes. A typical access of |
| 95 | // the current value of the name property would be: |
| 96 | // |
| 97 | // ExampleClient::Properties* p = example_client->GetProperties(object_path); |
| 98 | // std::string name = p->name.value(); |
| 99 | // |
| 100 | // Normally these values are updated from signals emitted by the remote object, |
| 101 | // in case an explicit round-trip is needed to obtain the current value, the |
| 102 | // Get() method can be used and indicates whether or not the value update was |
| 103 | // successful. The updated value can be obtained in the callback using the |
| 104 | // value() method. |
| 105 | // |
| 106 | // p->children.Get(base::Bind(&OnGetChildren)); |
| 107 | // |
| 108 | // A new value can be set using the Set() method, the callback indicates |
| 109 | // success only; it is up to the remote object when (and indeed if) it updates |
| 110 | // the property value, and whether it emits a signal or a Get() call is |
| 111 | // required to obtain it. |
| 112 | // |
| 113 | // p->version.Set(20, base::Bind(&OnSetVersion)) |
| 114 | |
| 115 | namespace dbus { |
| 116 | |
| 117 | // D-Bus Properties interface constants, declared here rather than |
| 118 | // in property.cc because template methods use them. |
| 119 | const char kPropertiesInterface[] = "org.freedesktop.DBus.Properties"; |
| 120 | const char kPropertiesGetAll[] = "GetAll"; |
| 121 | const char kPropertiesGet[] = "Get"; |
| 122 | const char kPropertiesSet[] = "Set"; |
| 123 | const char kPropertiesChanged[] = "PropertiesChanged"; |
| 124 | |
| 125 | class PropertySet; |
| 126 | |
| 127 | // PropertyBase is an abstract base-class consisting of the parts of |
| 128 | // the Property<> template that are not type-specific, such as the |
| 129 | // associated PropertySet, property name, and the type-unsafe parts |
| 130 | // used by PropertySet. |
| 131 | class PropertyBase { |
| 132 | public: |
| 133 | PropertyBase() : property_set_(NULL) {} |
| 134 | |
| 135 | // Initializes the |property_set| and property |name| so that method |
| 136 | // calls may be made from this class. This method is called by |
| 137 | // PropertySet::RegisterProperty(), there should be no need to call it |
| 138 | // directly. |
| 139 | void Init(PropertySet* property_set, const std::string& name); |
| 140 | |
| 141 | // Retrieves the name of this property, this may be useful in observers |
| 142 | // to avoid specifying the name in more than once place, e.g. |
| 143 | // |
| 144 | // void Client::PropertyChanged(const dbus::ObjectPath& object_path, |
| 145 | // const std::string &property_name) { |
| 146 | // Properties& properties = GetProperties(object_path); |
| 147 | // if (property_name == properties.version.name()) { |
| 148 | // // Handle version property changing |
| 149 | // } |
| 150 | // } |
| 151 | const std::string& name() { return name_; } |
| 152 | |
| 153 | // Method used by PropertySet to retrieve the value from a MessageReader, |
| 154 | // no knowledge of the contained type is required, this method returns |
| 155 | // true if its expected type was found, false if not. |
| 156 | virtual bool PopValueFromReader(MessageReader*) = 0; |
| 157 | |
| 158 | protected: |
| 159 | // Retrieves the associated property set. |
| 160 | PropertySet* property_set() { return property_set_; } |
| 161 | |
| 162 | private: |
| 163 | // Pointer to the associated property set. |
| 164 | PropertySet* property_set_; |
| 165 | |
| 166 | // Name of the property. |
| 167 | std::string name_; |
| 168 | |
| 169 | DISALLOW_COPY_AND_ASSIGN(PropertyBase); |
| 170 | }; |
| 171 | |
| 172 | // PropertySet groups a collection of properties for a remote object |
| 173 | // together into a single structure, fixing their types and name such |
| 174 | // that calls made through it are type-safe. |
| 175 | // |
| 176 | // Clients always sub-class this to add the properties, and should always |
| 177 | // provide a constructor that chains up to this and then calls |
| 178 | // RegisterProperty() for each property defined. |
| 179 | // |
| 180 | // After creation, client code should call ConnectSignals() and most likely |
| 181 | // GetAll() to seed initial values and update as changes occur. |
| 182 | class PropertySet { |
| 183 | public: |
| 184 | // Callback for changes to cached values of properties, either notified |
| 185 | // via signal, or as a result of calls to Get() and GetAll(). The |name| |
| 186 | // argument specifies the name of the property changed. |
| 187 | typedef base::Callback<void(const std::string& name)> PropertyChangedCallback; |
| 188 | |
| 189 | // Construct a property set, |object_proxy| specifies the proxy for the |
| 190 | // remote object that these properties are for, care should be taken to |
| 191 | // ensure that this object does not outlive the lifetime of the proxy; |
| 192 | // |interface| specifies the D-Bus interface of these properties, and |
| 193 | // |property_changed_callback| specifies the callback for when properties |
| 194 | // are changed, this may be a NULL callback. |
| 195 | PropertySet(ObjectProxy* object_proxy, const std::string& interface, |
| 196 | PropertyChangedCallback property_changed_callback); |
| 197 | |
| 198 | // Destructor; we don't hold on to any references or memory that needs |
| 199 | // explicit clean-up, but clang thinks we might. |
keybuk@chromium.org | 82e082a | 2012-02-17 10:01:18 +0900 | [diff] [blame^] | 200 | virtual ~PropertySet(); |
keybuk@chromium.org | 7e0c493 | 2012-02-15 13:21:08 +0900 | [diff] [blame] | 201 | |
| 202 | // Registers a property, generally called from the subclass constructor; |
| 203 | // pass the |name| of the property as used in method calls and signals, |
| 204 | // and the pointer to the |property| member of the structure. This will |
| 205 | // call the PropertyBase::Init method. |
| 206 | void RegisterProperty(const std::string& name, PropertyBase* property); |
| 207 | |
| 208 | // Call after construction to connect property change notification |
| 209 | // signals. Sub-classes may override to use different D-Bus signals. |
| 210 | void ConnectSignals(); |
| 211 | |
| 212 | // Methods connected by ConnectSignals() and called by dbus:: when |
| 213 | // a property is changed. Sub-classes may override if the property |
| 214 | // changed signal provides different arguments. |
| 215 | virtual void ChangedReceived(Signal*); |
| 216 | virtual void ChangedConnected(const std::string& interface_name, |
| 217 | const std::string& signal_name, |
| 218 | bool success); |
| 219 | |
| 220 | // Queries the remove object for values of all properties and updates |
| 221 | // initial values. Sub-classes may override to use a different D-Bus |
| 222 | // method, or if the remote object does not support retrieving all |
| 223 | // properties, either ignore or obtain each property value individually. |
| 224 | void GetAll(); |
| 225 | virtual void OnGetAll(Response* response); |
| 226 | |
| 227 | // Update properties by reading an array of dictionary entries, each |
| 228 | // containing a string with the name and a variant with the value, from |
| 229 | // |message_reader|. Returns false if message in incorrect format. |
| 230 | bool UpdatePropertiesFromReader(MessageReader* reader); |
| 231 | |
| 232 | // Updates a single property by reading a string with the name and a |
| 233 | // variant with the value from |message_reader|. Returns false if message |
| 234 | // in incorrect format, or property type doesn't match. |
| 235 | bool UpdatePropertyFromReader(MessageReader* reader); |
| 236 | |
| 237 | // Calls the property changed callback passed to the constructor, used |
| 238 | // by sub-classes that do not call UpdatePropertiesFromReader() or |
| 239 | // UpdatePropertyFromReader(). Takes the |name| of the changed property. |
| 240 | void NotifyPropertyChanged(const std::string& name); |
| 241 | |
| 242 | // Retrieves the object proxy this property set was initialized with, |
| 243 | // provided for sub-classes overriding methods that make D-Bus calls |
| 244 | // and for Property<>. |
| 245 | ObjectProxy* object_proxy() { return object_proxy_; } |
| 246 | |
| 247 | // Retrieves the interface of this property set. |
| 248 | const std::string& interface() { return interface_; } |
| 249 | |
| 250 | protected: |
| 251 | // Get a weak pointer to this property set, provided so that sub-classes |
| 252 | // overriding methods that make D-Bus calls may use the existing (or |
| 253 | // override) callbacks without providing their own weak pointer factory. |
| 254 | base::WeakPtr<PropertySet> GetWeakPtr() { |
| 255 | return weak_ptr_factory_.GetWeakPtr(); |
| 256 | } |
| 257 | |
| 258 | private: |
| 259 | // Pointer to object proxy for making method calls. |
| 260 | ObjectProxy* object_proxy_; |
| 261 | |
| 262 | // Interface of property, e.g. "org.chromium.ExampleService", this is |
| 263 | // distinct from the interface of the method call itself which is the |
| 264 | // general D-Bus Properties interface "org.freedesktop.DBus.Properties". |
| 265 | std::string interface_; |
| 266 | |
| 267 | // Callback for property changes. |
| 268 | PropertyChangedCallback property_changed_callback_; |
| 269 | |
| 270 | // Map of properties (as PropertyBase*) defined in the structure to |
| 271 | // names as used in D-Bus method calls and signals. The base pointer |
| 272 | // restricts property access via this map to type-unsafe and non-specific |
| 273 | // actions only. |
| 274 | typedef std::map<const std::string, PropertyBase*> PropertiesMap; |
| 275 | PropertiesMap properties_map_; |
| 276 | |
| 277 | // Weak pointer factory as D-Bus callbacks may last longer than these |
| 278 | // objects. |
| 279 | base::WeakPtrFactory<PropertySet> weak_ptr_factory_; |
| 280 | |
| 281 | DISALLOW_COPY_AND_ASSIGN(PropertySet); |
| 282 | }; |
| 283 | |
| 284 | // Property template, this defines the type-specific and type-safe methods |
| 285 | // of properties that can be accessed as members of a PropertySet structure. |
| 286 | // |
| 287 | // Properties provide a cached value that has an initial sensible default |
| 288 | // until the reply to PropertySet::GetAll() is retrieved and is updated by |
| 289 | // all calls to that method, Property<>::Get() and property changed signals |
| 290 | // handled by PropertySet. It can be obtained by calling value() on the |
| 291 | // property. |
| 292 | // |
| 293 | // It is recommended that this cached value be used where necessary, with |
| 294 | // code using PropertySet::PropertyChangedCallback to be notified of changes, |
| 295 | // rather than incurring a round-trip to the remote object for each property |
| 296 | // access. |
| 297 | // |
| 298 | // Where a round-trip is necessary, the Get() method is provided. And to |
| 299 | // update the remote object value, the Set() method is also provided. |
| 300 | // |
| 301 | // Handling of particular D-Bus types is performed via specialization, |
| 302 | // typically the PopValueFromReader() and AppendToWriter() methods will need |
| 303 | // to be provided, and in rare cases a constructor to provide a default value. |
| 304 | // Specializations for basic D-Bus types, strings, object paths and arrays |
| 305 | // are provided for you. |
| 306 | template <class T> |
| 307 | class Property : public PropertyBase { |
| 308 | public: |
| 309 | // Callback for Get() method, |success| indicates whether or not the |
| 310 | // value could be retrived, if true the new value can be obtained by |
| 311 | // calling value() on the property. |
| 312 | typedef base::Callback<void(bool success)> GetCallback; |
| 313 | |
| 314 | // Callback for Set() method, |success| indicates whether or not the |
| 315 | // new property value was accepted by the remote object. |
| 316 | typedef base::Callback<void(bool success)> SetCallback; |
| 317 | |
| 318 | Property() : weak_ptr_factory_(this) {} |
| 319 | |
| 320 | // Retrieves the cached value. |
| 321 | const T& value() { return value_; } |
| 322 | |
| 323 | // Requests an updated value from the remote object incurring a |
| 324 | // round-trip. |callback| will be called when the new value is available. |
| 325 | // This may not be implemented by some interfaces, and may be overriden by |
| 326 | // sub-classes if interfaces use different method calls. |
| 327 | void Get(GetCallback callback) { |
| 328 | DVLOG(1) << "Get: " << name(); |
| 329 | |
| 330 | MethodCall method_call(kPropertiesInterface, kPropertiesGet); |
| 331 | MessageWriter writer(&method_call); |
| 332 | writer.AppendString(property_set()->interface()); |
| 333 | writer.AppendString(name()); |
| 334 | |
| 335 | ObjectProxy *object_proxy = property_set()->object_proxy(); |
| 336 | DCHECK(object_proxy); |
| 337 | object_proxy->CallMethod(&method_call, |
| 338 | ObjectProxy::TIMEOUT_USE_DEFAULT, |
| 339 | base::Bind(&Property<T>::OnGet, |
| 340 | GetWeakPtr(), |
| 341 | callback)); |
| 342 | } |
| 343 | |
| 344 | // Callback for Get(), may be overriden by sub-classes if interfaces |
| 345 | // use different response arguments. |
| 346 | virtual void OnGet(SetCallback callback, Response* response) { |
| 347 | DVLOG(1) << "OnGet: " << name(); |
| 348 | if (!response) { |
| 349 | LOG(WARNING) << name() << ": Get: failed."; |
| 350 | return; |
| 351 | } |
| 352 | |
| 353 | MessageReader reader(response); |
| 354 | if (PopValueFromReader(&reader)) |
| 355 | property_set()->NotifyPropertyChanged(name()); |
| 356 | |
| 357 | if (!callback.is_null()) |
| 358 | callback.Run(response); |
| 359 | } |
| 360 | |
| 361 | // Requests that the remote object change the property value to |value|, |
| 362 | // |callback| will be called to indicate the success or failure of the |
| 363 | // request, however the new value may not be available depending on the |
| 364 | // remote object. This method may be overriden by sub-classes if |
| 365 | // interfaces use different method calls. |
| 366 | void Set(const T& value, SetCallback callback) { |
| 367 | DVLOG(1) << "Set: " << name(); |
| 368 | |
| 369 | MethodCall method_call(kPropertiesInterface, kPropertiesSet); |
| 370 | MessageWriter writer(&method_call); |
| 371 | writer.AppendString(property_set()->interface()); |
| 372 | writer.AppendString(name()); |
| 373 | AppendToWriter(&writer, value); |
| 374 | |
| 375 | ObjectProxy *object_proxy = property_set()->object_proxy(); |
| 376 | DCHECK(object_proxy); |
| 377 | object_proxy->CallMethod(&method_call, |
| 378 | ObjectProxy::TIMEOUT_USE_DEFAULT, |
| 379 | base::Bind(&Property<T>::OnSet, |
| 380 | GetWeakPtr(), |
| 381 | callback)); |
| 382 | } |
| 383 | |
| 384 | // Callback for Set(), may be overriden by sub-classes if interfaces |
| 385 | // use different response arguments. |
| 386 | virtual void OnSet(SetCallback callback, Response* response) { |
| 387 | DVLOG(1) << "OnSet: " << name(); |
| 388 | LOG_IF(WARNING, !response) << name() << ": Set: failed."; |
| 389 | if (!callback.is_null()) |
| 390 | callback.Run(response); |
| 391 | } |
| 392 | |
| 393 | // Updates the cached property value by popping from |reader| which |
| 394 | // should be positioned at the property value, generally of variant |
| 395 | // type. Implementation provided by specialization. |
| 396 | virtual bool PopValueFromReader(MessageReader* reader); |
| 397 | |
| 398 | // Appends the passed |value| to |writer|, generally as a variant type. |
| 399 | // Implementation provided by specialization. |
| 400 | virtual void AppendToWriter(MessageWriter* writer, const T& value); |
| 401 | |
| 402 | protected: |
| 403 | // Get a weak pointer to this propertyt, provided so that sub-classes |
| 404 | // overriding methods that make D-Bus calls may use the existing (or |
| 405 | // override) callbacks without providing their own weak pointer factory. |
| 406 | base::WeakPtr<Property<T> > GetWeakPtr() { |
| 407 | return weak_ptr_factory_.GetWeakPtr(); |
| 408 | } |
| 409 | |
| 410 | private: |
| 411 | // Current cached value of the property. |
| 412 | T value_; |
| 413 | |
| 414 | // Weak pointer factory as D-Bus callbacks may last longer than these |
| 415 | // objects. |
| 416 | base::WeakPtrFactory<Property<T> > weak_ptr_factory_; |
| 417 | }; |
| 418 | |
| 419 | } // namespace dbus |
| 420 | |
| 421 | #endif // DBUS_PROPERTY_H_ |