Add discovery session

components/net/bluetooth_thread.rs

@@ -4,6 +4,7 @@
 
 use device::bluetooth::BluetoothAdapter;
 use device::bluetooth::BluetoothDevice;
+use device::bluetooth::BluetoothDiscoverySession;
 use device::bluetooth::BluetoothGATTCharacteristic;
 use device::bluetooth::BluetoothGATTDescriptor;
 use device::bluetooth::BluetoothGATTService;
@@ -16,6 +17,8 @@ use net_traits::bluetooth_thread::{BluetoothResult, BluetoothServiceMsg, Bluetoo
 use std::borrow::ToOwned;
 use std::collections::HashMap;
 use std::string::String;
+use std::thread;
+use std::time::Duration;
 use util::thread::spawn_named;
 
 const ADAPTER_ERROR: &'static str = "No adapter found";
@@ -25,6 +28,8 @@ const PRIMARY_SERVICE_ERROR: &'static str = "No primary service found";
 const CHARACTERISTIC_ERROR: &'static str = "No characteristic found";
 const DESCRIPTOR_ERROR: &'static str = "No descriptor found";
 const VALUE_ERROR: &'static str = "No characteristic or descriptor found with that id";
+// The discovery session needs some time to find any nearby devices
+const DISCOVERY_TIMEOUT_MS: u64 = 1500;
 
 bitflags! {
     flags Flags: u32 {
@@ -355,11 +360,13 @@ impl BluetoothManager {
             Some(a) => a,
             None => return drop(sender.send(Err(String::from(ADAPTER_ERROR)))),
         };
-        let devices = self.get_and_cache_devices(&mut adapter);
-        if devices.is_empty() {
-            return drop(sender.send(Err(String::from(DEVICE_ERROR))));
+        if let Some(ref session) = BluetoothDiscoverySession::create_session(adapter.get_object_path()).ok() {
+            if session.start_discovery().is_ok() {
+                thread::sleep(Duration::from_millis(DISCOVERY_TIMEOUT_MS));
+            }
+            let _ = session.stop_discovery();
         }
-
+        let devices = self.get_and_cache_devices(&mut adapter);
         let matched_devices: Vec<BluetoothDevice> = devices.into_iter()
                                                            .filter(|d| matches_filters(d, options.get_filters()))
                                                            .collect();