[bluetooth] Graciously handle systems without DBus (#10153)

bundles/org.openhab.binding.bluetooth.bluez/src/main/java/org/openhab/binding/bluetooth/bluez/internal/DeviceManagerFactory.java

@@ -51,7 +51,7 @@ public class DeviceManagerFactory {
 
     private final BlueZPropertiesChangedHandler changeHandler = new BlueZPropertiesChangedHandler();
 
-    private @Nullable CompletableFuture<DeviceManager> deviceManagerFuture;
+    private @Nullable CompletableFuture<@Nullable DeviceManager> deviceManagerFuture;
     private @Nullable CompletableFuture<DeviceManagerWrapper> deviceManagerWrapperFuture;
 
     public BlueZPropertiesChangedHandler getPropertiesChangedHandler() {
@@ -79,7 +79,13 @@ public class DeviceManagerFactory {
                 // Experimental - seems reuse does not work
             } catch (IllegalStateException e) {
                 // Exception caused by first call to the library
+                try {
                     return DeviceManager.createInstance(false);
+                } catch (DBusException ex) {
+                    // we might be on a system without DBus, such as macOS or Windows
+                    logger.debug("Failed to initialize DeviceManager: {}", ex.getMessage());
+                    return null;
+                }
             }
         }, scheduler);
 
@@ -90,8 +96,10 @@ public class DeviceManagerFactory {
                 int count = tryCount.incrementAndGet();
                 try {
                     logger.debug("Registering property handler attempt: {}", count);
+                    if (devManager != null) {
                         devManager.registerPropertyHandler(changeHandler);
                         logger.debug("Successfully registered property handler");
+                    }
                     return new DeviceManagerWrapper(devManager);
                 } catch (DBusException e) {
                     if (count < 3) {
@@ -103,8 +111,13 @@ public class DeviceManagerFactory {
             }, scheduler);
         }).whenComplete((devManagerWrapper, th) -> {
             if (th != null) {
+                if (th.getCause() instanceof DBusException) {
+                    // we might be on a system without DBus, such as macOS or Windows
+                    logger.debug("Failed to initialize DeviceManager: {}", th.getMessage());
+                } else {
                     logger.warn("Failed to initialize DeviceManager: {}", th.getMessage());
                 }
+            }
         });
     }
 
@@ -114,7 +127,11 @@ public class DeviceManagerFactory {
         if (stage1 != null) {
             if (!stage1.cancel(true)) {
                 // a failure to cancel means that the stage completed normally
-                stage1.thenAccept(DeviceManager::closeConnection);
+                stage1.thenAccept(devManager -> {
+                    if (devManager != null) {
+                        devManager.closeConnection();
+                    }
+                });
             }
         }
         this.deviceManagerFuture = null;

bundles/org.openhab.binding.bluetooth.bluez/src/main/java/org/openhab/binding/bluetooth/bluez/internal/DeviceManagerWrapper.java

@@ -14,6 +14,7 @@ package org.openhab.binding.bluetooth.bluez.internal;
 
 import java.util.Collection;
 import java.util.List;
+import java.util.Set;
 
 import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
@@ -32,20 +33,26 @@ import com.github.hypfvieh.bluetooth.wrapper.BluetoothDevice;
 @NonNullByDefault
 public class DeviceManagerWrapper {
 
-    private DeviceManager deviceManager;
+    private @Nullable DeviceManager deviceManager;
 
-    public DeviceManagerWrapper(DeviceManager deviceManager) {
+    public DeviceManagerWrapper(@Nullable DeviceManager deviceManager) {
         this.deviceManager = deviceManager;
     }
 
     public synchronized Collection<BluetoothAdapter> scanForBluetoothAdapters() {
+        if (deviceManager != null) {
             return deviceManager.scanForBluetoothAdapters();
+        } else {
+            return Set.of();
+        }
     }
 
     public synchronized @Nullable BluetoothAdapter getAdapter(BluetoothAddress address) {
+        DeviceManager devMgr = deviceManager;
+        if (devMgr != null) {
             // we don't use `deviceManager.getAdapter` here since it might perform a scan if the adapter is missing.
             String addr = address.toString();
-        List<BluetoothAdapter> adapters = deviceManager.getAdapters();
+            List<BluetoothAdapter> adapters = devMgr.getAdapters();
             if (adapters != null) {
                 for (BluetoothAdapter btAdapter : adapters) {
                     String btAddr = btAdapter.getAddress();
@@ -54,10 +61,15 @@ public class DeviceManagerWrapper {
                     }
                 }
             }
+        }
         return null;
     }
 
     public synchronized List<BluetoothDevice> getDevices(BluetoothAdapter adapter) {
+        if (deviceManager != null) {
             return deviceManager.getDevices(adapter.getAddress(), true);
+        } else {
+            return List.of();
+        }
     }
 }