fix: drop WS server if work complete (#399)

* fix: drop WS server if work complete

* fix: remove closed subscriptions

* fix: handle error correctly

* style: better notification handling

ethers-providers/src/transports/ws.rs

@@ -12,6 +12,7 @@ use futures_util::{
     stream::{Fuse, Stream, StreamExt},
 };
 use serde::{de::DeserializeOwned, Serialize};
+use std::collections::btree_map::Entry;
 use std::{
     collections::BTreeMap,
     fmt::{self, Debug},
@@ -198,6 +199,14 @@ where
         }
     }
 
+    /// Returns whether the all work has been completed.
+    ///
+    /// If this method returns `true`, then the `instructions` channel has been closed and all
+    /// pending requests and subscriptions have been completed.
+    fn is_done(&self) -> bool {
+        self.instructions.is_done() && self.pending.is_empty() && self.subscriptions.is_empty()
+    }
+
     /// Spawns the event loop
     fn spawn(mut self)
     where
@@ -205,6 +214,10 @@ where
     {
         let f = async move {
             loop {
+                if self.is_done() {
+                    tracing::info!("work complete");
+                    break;
+                }
                 match self.tick().await {
                     Err(ClientError::UnexpectedClose) => {
                         tracing::error!("{}", ClientError::UnexpectedClose);
@@ -288,10 +301,14 @@ where
             }
             Ok(Incoming::Notification(notification)) => {
                 let id = notification.params.subscription;
-                if let Some(stream) = self.subscriptions.get(&id) {
-                    stream
-                        .unbounded_send(notification.params.result)
-                        .map_err(to_client_error)?;
+                if let Entry::Occupied(stream) = self.subscriptions.entry(id) {
+                    if let Err(err) = stream.get().unbounded_send(notification.params.result) {
+                        if err.is_disconnected() {
+                            // subscription channel was closed on the receiver end
+                            stream.remove();
+                        }
+                        return Err(to_client_error(err));
+                    }
                 }
             }
         }