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