[CrOS Tether] Do not register a new Bluetooth advertisement until any previous identical advertisem…

chromeos/components/tether/ble_advertiser.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROMEOS_COMPONENTS_TETHER_BLE_ADVERTISER_H_
 #define CHROMEOS_COMPONENTS_TETHER_BLE_ADVERTISER_H_
 
 #include <map>
+#include <unordered_set>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "components/cryptauth/foreground_eid_generator.h"
 #include "components/cryptauth/remote_device.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 #include "device/bluetooth/bluetooth_advertisement.h"
 
 namespace cryptauth {
 class LocalDeviceDataProvider;
@@ skipping 18 matching lines @@
   virtual ~BleAdvertiser();
 
   virtual bool StartAdvertisingToDevice(
       const cryptauth::RemoteDevice& remote_device);
   virtual bool StopAdvertisingToDevice(
       const cryptauth::RemoteDevice& remote_device);
 
  private:
   friend class BleAdvertiserTest;
 
+  // One IndividualAdvertisement is created for each device to which
+  // BleAdvertiser should be advertising. When an IndividualAdvertisement is
+  // created, it starts trying to advertise to its associated device ID;
+  // likewise, when it is destroyed, it stops advertising if necessary.
+  //
+  // However, because unregistering an advertisement is an asynchronous
+  // operation, it is possible that if an IndividualAdvertisement for one device
+  // is created just after another IndividualAdvertisement for the same device
+  // was destroyed, the previous advertisement was not fully unregistered.
+  // If that is the case, the newly-created IndividualAdvertisement must wait

[Ryan Hansberry, 2017/07/11 21:27:41]

please explicitly mention OnPreviousAdvertisementUnregistered()

[Kyle Horimoto, 2017/07/12 02:22:04]

Done.

+  // until the previous advertisement was unregistered.
   class IndividualAdvertisement
       : public device::BluetoothAdapter::Observer,
         public device::BluetoothAdvertisement::Observer {
    public:
     IndividualAdvertisement(
         const std::string& device_id,
         scoped_refptr<device::BluetoothAdapter> adapter,
-        std::unique_ptr<cryptauth::DataWithTimestamp> advertisement_data);
+        std::unique_ptr<cryptauth::DataWithTimestamp> advertisement_data,
+        const base::Closure& on_advertisement_unregistered_callback,
+        std::unordered_set<std::string>* active_advertisement_device_ids_set);
     ~IndividualAdvertisement() override;
 
+    // Callback for when a previously-registered advertisement corresponding to
+    // |device_id_| has been unregistered.
+    void OnPreviousAdvertisementUnregistered();
+
     // device::BluetoothAdapter::Observer
     void AdapterPoweredChanged(device::BluetoothAdapter* adapter,
                                bool powered) override;
 
     // device::BluetoothAdvertisement::Observer
     void AdvertisementReleased(
         device::BluetoothAdvertisement* advertisement) override;
 
    private:
     friend class BleAdvertiserTest;
@@ skipping 11 matching lines @@
 
     std::unique_ptr<device::BluetoothAdvertisement::ServiceData>
     CreateServiceData() const;
 
     std::string device_id_;
     scoped_refptr<device::BluetoothAdapter> adapter_;
     std::unique_ptr<cryptauth::DataWithTimestamp> advertisement_data_;
     bool is_initializing_advertising_;
     scoped_refptr<device::BluetoothAdvertisement> advertisement_;
 
+    base::Closure on_advertisement_unregistered_callback_;
+    std::unordered_set<std::string>* active_advertisement_device_ids_set_;
+
     base::WeakPtrFactory<IndividualAdvertisement> weak_ptr_factory_;
 
     DISALLOW_COPY_AND_ASSIGN(IndividualAdvertisement);
   };
 
   BleAdvertiser(
       scoped_refptr<device::BluetoothAdapter> adapter,
       std::unique_ptr<cryptauth::ForegroundEidGenerator> eid_generator,
       const cryptauth::RemoteBeaconSeedFetcher* remote_beacon_seed_fetcher,
       const cryptauth::LocalDeviceDataProvider* local_device_data_provider);
 
+  void OnAdvertisementUnregistered(const std::string& associated_device_id);
+
   scoped_refptr<device::BluetoothAdapter> adapter_;
 
   std::unique_ptr<cryptauth::ForegroundEidGenerator> eid_generator_;
   // Not owned by this instance and must outlive it.
   const cryptauth::RemoteBeaconSeedFetcher* remote_beacon_seed_fetcher_;
   const cryptauth::LocalDeviceDataProvider* local_device_data_provider_;
 
   std::map<std::string, std::unique_ptr<IndividualAdvertisement>>
       device_id_to_advertisement_map_;
+  std::unordered_set<std::string> active_advertisement_device_ids_set_;
+
+  base::WeakPtrFactory<BleAdvertiser> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BleAdvertiser);
 };
 
 }  // namespace tether
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_COMPONENTS_TETHER_BLE_ADVERTISER_H_