device/bluetooth/bluetooth_discovery_session.h

   1 // Copyright 2014 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 DEVICE_BLUETOOTH_BLUETOOTH_DISCOVERY_SESSION_H_
   6 #define DEVICE_BLUETOOTH_BLUETOOTH_DISCOVERY_SESSION_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/weak_ptr.h"
  11 #include "device/bluetooth/bluetooth_export.h"
  12
  13 namespace device {
  14
  15 class BluetoothAdapter;
  16
  17 // BluetoothDiscoverySession represents a current active or inactive device
  18 // discovery session. Instances of this class are obtained by calling
  19 // BluetoothAdapter::StartDiscoverySession. The Bluetooth adapter will be
  20 // constantly searching for nearby devices, as long as at least one instance
  21 // of an active BluetoothDiscoverySession exists. A BluetoothDiscoverySession is
  22 // considered active, as long as the adapter is discovering AND the owner of the
  23 // instance has not called BluetoothDiscoverySession::Stop. A
  24 // BluetoothDiscoverySession might unexpectedly become inactive, if the adapter
  25 // unexpectedly stops discovery. Users can implement the
  26 // AdapterDiscoveringChanged method of the BluetoothAdapter::Observer interface
  27 // to be notified of such a change and promptly request a new
  28 // BluetoothDiscoverySession if their existing sessions have become inactive.
  29 class DEVICE_BLUETOOTH_EXPORT BluetoothDiscoverySession {
  30  public:
  31   // The ErrorCallback is used by methods to asynchronously report errors.
  32   typedef base::Closure ErrorCallback;
  33
  34   // Destructor automatically terminates the discovery session. If this
  35   // results in a call to the underlying system to stop device discovery
  36   // (i.e. this instance represents the last active discovery session),
  37   // the call may not always succeed. To be notified of such failures,
  38   // users are highly encouraged to call BluetoothDiscoverySession::Stop,
  39   // instead of relying on the destructor.
  40   virtual ~BluetoothDiscoverySession();
  41
  42   // Returns true if the session is active, false otherwise. If false, the
  43   // adapter might still be discovering as there might still be other active
  44   // sessions; this just means that this instance no longer has a say in
  45   // whether or not discovery should continue. In this case, the application
  46   // should request a new BluetoothDiscoverySession to make sure that device
  47   // discovery continues.
  48   virtual bool IsActive() const;
  49
  50   // Requests this discovery session instance to stop. If this instance is
  51   // active, the session will stop. On success, |callback| is called and
  52   // on error |error_callback| is called. After a successful invocation, the
  53   // adapter may or may not stop device discovery, depending on whether or not
  54   // other active discovery sessions are present. Users are highly encouraged
  55   // to call this method to end a discovery session, instead of relying on the
  56   // destructor, so that they can be notified of the result via the callback
  57   // arguments.
  58   virtual void Stop(const base::Closure& callback,
  59                     const ErrorCallback& error_callback);
  60
  61  protected:
  62   explicit BluetoothDiscoverySession(scoped_refptr<BluetoothAdapter> adapter);
  63
  64  private:
  65   friend class BluetoothAdapter;
  66
  67   // Internal callback invoked when a call to Stop has succeeded.
  68   void OnStop(const base::Closure& callback);
  69
  70   // Marks this instance as inactive. Called by BluetoothAdapter to mark a
  71   // session as inactive in the case of an unexpected change to the adapter
  72   // discovery state.
  73   void MarkAsInactive();
  74
  75   // Whether or not this instance represents an active discovery session.
  76   bool active_;
  77
  78   // The adapter that created this instance.
  79   scoped_refptr<BluetoothAdapter> adapter_;
  80
  81   // Note: This should remain the last member so it'll be destroyed and
  82   // invalidate its weak pointers before any other members are destroyed.
  83   base::WeakPtrFactory<BluetoothDiscoverySession> weak_ptr_factory_;
  84
  85   DISALLOW_COPY_AND_ASSIGN(BluetoothDiscoverySession);
  86 };
  87
  88 }  // namespace device
  89
  90 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_DISCOVERY_SESSION_H_