feat: add Client.stop(subscription_id)

Maintaining a list of subscriptions on a connection to be able to stop
them with a list of Subscription items is difficult/complex due to the
generics. I couldn't figure out how to box them when I am sending
different subscription types.

Instead just exposing the subscription id and allowing you to cancel the
subscription by id on the client itself allows you to manage
subscriptions easily and not have to worry about the request types at
all.

Author: luca992

src/client/mod.rs

@@ -121,6 +121,18 @@ impl Client {
         })
     }
 
+    /// Stops a subscription by id
+    ///
+    /// # Errors
+    ///
+    /// Will return `Err` if the connection actor has already been shut down.
+    pub async fn stop(self, subscription_id: SubscriptionId) -> Result<(), Error> {
+        self.actor
+            .send(ConnectionCommand::Cancel(subscription_id))
+            .await
+            .map_err(|error| Error::Send(error.to_string()))
+    }
+
     /// Gracefully closes the connection
     ///
     /// This will stop all running subscriptions and shut down the [`ConnectionActor`] wherever

src/client/subscription.rs

@@ -41,11 +41,20 @@ impl<Operation> Subscription<Operation>
 where
     Operation: GraphqlOperation + Send,
 {
-    /// Stops the subscription by sending a Complete message to the server.
+    /// Returns the identifier for this subscription. 
+    ///
+    /// This can be used with [`crate::Client::stop`] to stop
+    /// a running subscription without needing access to the `Subscription`
+    /// itself.
+    pub fn id(&self) -> SubscriptionId {
+        self.id
+    }
+
+    /// Stops this subscription
     ///
     /// # Errors
     ///
-    /// Will return `Err` if the stop operation fails.
+    /// Will return `Err` if the connection actor has already been shut down.
     pub async fn stop(self) -> Result<(), Error> {
         self.actor
             .send(ConnectionCommand::Cancel(self.id))