dbus/exported_object.h

   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_EXPORTED_OBJECT_H_
   6 #define DBUS_EXPORTED_OBJECT_H_
   7
   8 #include <dbus/dbus.h>
   9
  10 #include <map>
  11 #include <string>
  12 #include <utility>
  13
  14 #include "base/callback.h"
  15 #include "base/memory/ref_counted.h"
  16 #include "base/synchronization/waitable_event.h"
  17 #include "base/threading/platform_thread.h"
  18 #include "base/time/time.h"
  19 #include "dbus/dbus_export.h"
  20 #include "dbus/object_path.h"
  21
  22 namespace dbus {
  23
  24 class Bus;
  25 class MethodCall;
  26 class Response;
  27 class Signal;
  28
  29 // ExportedObject is used to export objects and methods to other D-Bus
  30 // clients.
  31 //
  32 // ExportedObject is a ref counted object, to ensure that |this| of the
  33 // object is alive when callbacks referencing |this| are called.
  34 class CHROME_DBUS_EXPORT ExportedObject
  35     : public base::RefCountedThreadSafe<ExportedObject> {
  36  public:
  37   // Client code should use Bus::GetExportedObject() instead of this
  38   // constructor.
  39   ExportedObject(Bus* bus, const ObjectPath& object_path);
  40
  41   // Called to send a response from an exported method. |response| is the
  42   // response message. Callers should pass NULL in the event of an error that
  43   // prevents the sending of a response.
  44   typedef base::Callback<void (scoped_ptr<Response> response)> ResponseSender;
  45
  46   // Called when an exported method is called. |method_call| is the request
  47   // message. |sender| is the callback that's used to send a response.
  48   //
  49   // |method_call| is owned by ExportedObject, hence client code should not
  50   // delete |method_call|.
  51   typedef base::Callback<void (MethodCall* method_call, ResponseSender sender)>
  52       MethodCallCallback;
  53
  54   // Called when method exporting is done.
  55   // |success| indicates whether exporting was successful or not.
  56   typedef base::Callback<void (const std::string& interface_name,
  57                                const std::string& method_name,
  58                                bool success)>
  59       OnExportedCallback;
  60
  61   // Exports the method specified by |interface_name| and |method_name|,
  62   // and blocks until exporting is done. Returns true on success.
  63   //
  64   // |method_call_callback| will be called in the origin thread, when the
  65   // exported method is called. As it's called in the origin thread,
  66   // |method_callback| can safely reference objects in the origin thread
  67   // (i.e. UI thread in most cases).
  68   //
  69   // IMPORTANT NOTE: You should export all methods before requesting a
  70   // service name by Bus::RequestOwnership/AndBlock(). If you do it in the
  71   // wrong order (i.e. request a service name then export methods), there
  72   // will be a short time period where your service is unable to respond to
  73   // method calls because these methods aren't yet exposed. This race is a
  74   // real problem as clients may start calling methods of your service as
  75   // soon as you acquire a service name, by watching the name owner change.
  76   //
  77   // BLOCKING CALL.
  78   virtual bool ExportMethodAndBlock(const std::string& interface_name,
  79                                     const std::string& method_name,
  80                                     MethodCallCallback method_call_callback);
  81
  82   // Requests to export the method specified by |interface_name| and
  83   // |method_name|. See Also ExportMethodAndBlock().
  84   //
  85   // |on_exported_callback| is called when the method is exported or
  86   // failed to be exported, in the origin thread.
  87   //
  88   // Must be called in the origin thread.
  89   virtual void ExportMethod(const std::string& interface_name,
  90                             const std::string& method_name,
  91                             MethodCallCallback method_call_callback,
  92                             OnExportedCallback on_exported_callback);
  93
  94   // Requests to send the signal from this object. The signal will be sent
  95   // asynchronously from the message loop in the D-Bus thread.
  96   virtual void SendSignal(Signal* signal);
  97
  98   // Unregisters the object from the bus. The Bus object will take care of
  99   // unregistering so you don't have to do this manually.
 100   //
 101   // BLOCKING CALL.
 102   virtual void Unregister();
 103
 104  protected:
 105   // This is protected, so we can define sub classes.
 106   virtual ~ExportedObject();
 107
 108  private:
 109   friend class base::RefCountedThreadSafe<ExportedObject>;
 110
 111   // Helper function for ExportMethod().
 112   void ExportMethodInternal(const std::string& interface_name,
 113                             const std::string& method_name,
 114                             MethodCallCallback method_call_callback,
 115                             OnExportedCallback exported_callback);
 116
 117   // Called when the object is exported.
 118   void OnExported(OnExportedCallback on_exported_callback,
 119                   const std::string& interface_name,
 120                   const std::string& method_name,
 121                   bool success);
 122
 123   // Helper function for SendSignal().
 124   void SendSignalInternal(base::TimeTicks start_time,
 125                           DBusMessage* signal_message);
 126
 127   // Registers this object to the bus.
 128   // Returns true on success, or the object is already registered.
 129   //
 130   // BLOCKING CALL.
 131   bool Register();
 132
 133   // Handles the incoming request messages and dispatches to the exported
 134   // methods.
 135   DBusHandlerResult HandleMessage(DBusConnection* connection,
 136                                   DBusMessage* raw_message);
 137
 138   // Runs the method. Helper function for HandleMessage().
 139   void RunMethod(MethodCallCallback method_call_callback,
 140                  scoped_ptr<MethodCall> method_call,
 141                  base::TimeTicks start_time);
 142
 143   // Callback invoked by service provider to send a response to a method call.
 144   // Can be called immediately from a MethodCallCallback to implement a
 145   // synchronous service or called later to implement an asynchronous service.
 146   void SendResponse(base::TimeTicks start_time,
 147                     scoped_ptr<MethodCall> method_call,
 148                     scoped_ptr<Response> response);
 149
 150   // Called on completion of the method run from SendResponse().
 151   // Takes ownership of |method_call| and |response|.
 152   void OnMethodCompleted(scoped_ptr<MethodCall> method_call,
 153                          scoped_ptr<Response> response,
 154                          base::TimeTicks start_time);
 155
 156   // Called when the object is unregistered.
 157   void OnUnregistered(DBusConnection* connection);
 158
 159   // Redirects the function call to HandleMessage().
 160   static DBusHandlerResult HandleMessageThunk(DBusConnection* connection,
 161                                               DBusMessage* raw_message,
 162                                               void* user_data);
 163
 164   // Redirects the function call to OnUnregistered().
 165   static void OnUnregisteredThunk(DBusConnection* connection,
 166                                   void* user_data);
 167
 168   scoped_refptr<Bus> bus_;
 169   ObjectPath object_path_;
 170   bool object_is_registered_;
 171
 172   // The method table where keys are absolute method names (i.e. interface
 173   // name + method name), and values are the corresponding callbacks.
 174   typedef std::map<std::string, MethodCallCallback> MethodTable;
 175   MethodTable method_table_;
 176 };
 177
 178 }  // namespace dbus
 179
 180 #endif  // DBUS_EXPORTED_OBJECT_H_