crypto: Allow devices to be deleted from the crypto store.

src/crypto/machine.rs

@@ -427,12 +427,13 @@ impl OlmMachine {
             for device_id in deleted_devices {
                 if let Some(device) = stored_devices.get(device_id) {
                     device.mark_as_deleted();
-                    // TODO change this to a delete device.
+                    // TODO change this to a bulk deletion.
-                    self.store.save_device(device).await?;
+                    self.store.delete_device(device).await?;
                 }
             }
         }
 
+        // TODO change this to a bulk operation.
         for device in &changed_devices {
             self.store.save_device(device.clone()).await?;
         }

src/crypto/store/memorystore.rs

@@ -88,6 +88,11 @@ impl CryptoStore for MemoryStore {
         Ok(self.devices.get(user_id, device_id))
     }
 
+    async fn delete_device(&self, device: Device) -> Result<()> {
+        self.devices.remove(device.user_id(), device.device_id());
+        Ok(())
+    }
+
     async fn get_user_devices(&self, user_id: &UserId) -> Result<UserDevices> {
         Ok(self.devices.user_devices(user_id))
     }
@@ -181,6 +186,13 @@ mod test {
         let loaded_device = user_devices.get(device.device_id()).unwrap();
 
         assert_eq!(device, loaded_device);
+
+        store.delete_device(device.clone()).await.unwrap();
+        assert!(store
+            .get_device(device.user_id(), device.device_id())
+            .await
+            .unwrap()
+            .is_none());
     }
 
     #[tokio::test]

src/crypto/store/mod.rs

@@ -133,6 +133,13 @@ pub trait CryptoStore: Debug + Send + Sync {
     /// * `device` - The device that should be stored.
     async fn save_device(&self, device: Device) -> Result<()>;
 
+    /// Delete the given device from the store.
+    ///
+    /// # Arguments
+    ///
+    /// * `device` - The device that should be stored.
+    async fn delete_device(&self, device: Device) -> Result<()>;
+
     /// Get the device for the given user with the given device id.
     ///
     /// # Arguments

src/crypto/store/sqlite.rs

@@ -613,6 +613,10 @@ impl CryptoStore for SqliteStore {
         self.save_device_helper(device).await
     }
 
+    async fn delete_device(&self, device: Device) -> Result<()> {
+        todo!()
+    }
+
     async fn get_device(&self, user_id: &UserId, device_id: &DeviceId) -> Result<Option<Device>> {
         Ok(self.devices.get(user_id, device_id))
     }