Free some additional structures from winapi properly

src/sm_session_notifier.rs

@@ -16,7 +16,9 @@ use windows::{
             eRender, IAudioSessionControl2, IAudioSessionManager2, IAudioSessionNotification,
             IMMDeviceEnumerator, IMMNotificationClient, MMDeviceEnumerator, DEVICE_STATE_ACTIVE,
         },
-        System::Com::{CoCreateInstance, CLSCTX_ALL, STGM_READ},
+        System::Com::{
+            CoCreateInstance, StructuredStorage::PropVariantClear, CLSCTX_ALL, STGM_READ,
+        },
     },
 };
 
@@ -78,9 +80,7 @@ impl SMSessionNotifier {
                 }),
             }),
             session_notification: IAudioSessionNotification::from(SessionNotification {
-                observer: Box::new(SessionToMessage {
-                    sender
-                }),
+                observer: Box::new(SessionToMessage { sender }),
             }),
             notification_function: callback,
             receiver,
@@ -98,7 +98,6 @@ impl SMSessionNotifier {
                 let mmdevice = device?;
                 self.add_device(mmdevice)?;
             }
-            println!("All devices initialized.");
             Ok(())
         }
     }
@@ -117,9 +116,9 @@ impl SMSessionNotifier {
         self: &mut SMSessionNotifier,
         device: windows::Win32::Media::Audio::IMMDevice,
     ) -> Result<(), Box<dyn Error>> {
-        let sm: IAudioSessionManager2 = device.Activate(CLSCTX_ALL, None)?;
-        sm.RegisterSessionNotification(&self.session_notification)?;
-        let session_enumerator = sm.GetSessionEnumerator()?;
+        let session_manager: IAudioSessionManager2 = device.Activate(CLSCTX_ALL, None)?;
+        session_manager.RegisterSessionNotification(&self.session_notification)?;
+        let session_enumerator = session_manager.GetSessionEnumerator()?;
         let session_count = session_enumerator.GetCount()?;
         let device_sessions = (0..session_count)
             .map(|idx| {
@@ -132,13 +131,15 @@ impl SMSessionNotifier {
             (self.notification_function)(session);
         }
         let prop_store = device.OpenPropertyStore(STGM_READ)?;
-        let prop_var = prop_store.GetValue(&PKEY_Device_FriendlyName)?;
+        let mut prop_var = prop_store.GetValue(&PKEY_Device_FriendlyName)?;
         println!(
             "Device Added: {} Existing Sessions: {}",
             prop_var.Anonymous.Anonymous.Anonymous.pwszVal.to_string()?,
             session_count
         );
-        self.session_managers.push(sm);
+        PropVariantClear(&mut prop_var)?;
+
+        self.session_managers.push(session_manager);
         Ok(())
     }
 
@@ -161,6 +162,21 @@ impl SMSessionNotifier {
     }
 }
 
+impl Drop for SMSessionNotifier {
+    fn drop(&mut self) {
+        unsafe {
+            self.session_managers
+                .drain(..)
+                .map(|x| x.UnregisterSessionNotification(&self.session_notification))
+                .collect::<Result<(), _>>()
+                .unwrap();
+            self.device_enumerator
+                .UnregisterEndpointNotificationCallback(&self.device_notification_client)
+                .unwrap();
+        }
+    }
+}
+
 pub struct SMSessionNotifierThread {
     handle: Option<JoinHandle<()>>,
     sender: Sender<SMMessage>,