Auto merge of #11269 - szeged:discovery, r=jdm

Extend WebBluetooth with discovery session and dialog

Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data:
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy --faster` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

Either:
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because the there are no webbluetooth tests ye.

Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process.

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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 +17,10 @@ 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;
+#[cfg(target_os = "linux")]
+use tinyfiledialogs;
 use util::thread::spawn_named;
 
 const ADAPTER_ERROR: &'static str = "No adapter found";
@@ -25,6 +30,14 @@ 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;
+#[cfg(target_os = "linux")]
+const DIALOG_TITLE: &'static str = "Choose a device";
+#[cfg(target_os = "linux")]
+const DIALOG_COLUMN_ID: &'static str = "Id";
+#[cfg(target_os = "linux")]
+const DIALOG_COLUMN_NAME: &'static str = "Name";
 
 bitflags! {
     flags Flags: u32 {
@@ -203,6 +216,37 @@ impl BluetoothManager {
         None
     }
 
+    #[cfg(target_os = "linux")]
+    fn select_device(&mut self, devices: Vec<BluetoothDevice>) -> Option<String> {
+        let mut dialog_rows: Vec<String> = vec!();
+        for device in devices {
+            dialog_rows.extend_from_slice(&[device.get_address().unwrap_or("".to_string()),
+                                            device.get_name().unwrap_or("".to_string())]);
+        }
+        let dialog_rows: Vec<&str> = dialog_rows.iter()
+                                                .map(|s| s.as_ref())
+                                                .collect();
+        let dialog_rows: &[&str] = dialog_rows.as_slice();
+
+        if let Some(device) = tinyfiledialogs::list_dialog(DIALOG_TITLE,
+                                                           &[DIALOG_COLUMN_ID, DIALOG_COLUMN_NAME],
+                                                           Some(dialog_rows)) {
+            // The device string format will be "Address|Name". We need the first part of it.
+            return device.split("|").next().map(|s| s.to_string());
+        }
+        None
+    }
+
+    #[cfg(not(target_os = "linux"))]
+    fn select_device(&mut self, devices: Vec<BluetoothDevice>) -> Option<String> {
+        for device in devices {
+            if let Ok(address) = device.get_address() {
+                return Some(address);
+            }
+        }
+        None
+    }
+
     // Service
 
     fn get_and_cache_gatt_services(&mut self,
@@ -355,16 +399,18 @@ 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();
-        for device in matched_devices {
-            if let Ok(address) = device.get_address() {
+        if let Some(address) = self.select_device(matched_devices) {
+            if let Some(device) = self.get_device(&mut adapter, address.as_str()) {
                 let message = Ok(BluetoothDeviceMsg {
                                      id: address,
                                      name: device.get_name().ok(),

components/servo/Cargo.lock

@@ -2266,7 +2266,7 @@ dependencies = [
 [[package]]
 name = "tinyfiledialogs"
 version = "0.1.0"
-source = "git+https://github.com/jdm/tinyfiledialogs#686abf781f30b360a4c265964fd3744e2f61cf2d"
+source = "git+https://github.com/jdm/tinyfiledialogs#3a30f8f95686195cb3bcecfc77ff77277a624a53"
 dependencies = [
  "libc 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
 ]