pool: replace OnceLock with Option for the external notification sender

Replace `OnceLock` with `Option` for the external notification sender in `Relay` struct`. Removed the now unused `PoolNotificationSenderAlreadySet` error variant.

Signed-off-by: Yuki Kishimoto <[email protected]>

Author: yukibtc

crates/nostr-relay-pool/src/pool/inner.rs

@@ -143,12 +143,12 @@ impl InnerRelayPool {
         }
 
         // Compose new relay
-        let relay: Relay = Relay::new(url, self.state.clone(), opts);
+        let mut relay: Relay = Relay::new(url, self.state.clone(), opts);
 
         // Set notification sender
         relay
             .inner
-            .set_notification_sender(self.notification_sender.clone())?;
+            .set_notification_sender(self.notification_sender.clone());
 
         // If relay has `READ` flag, inherit pool subscriptions
         if relay.flags().has_read() {

crates/nostr-relay-pool/src/relay/error.rs

@@ -37,8 +37,6 @@ pub enum Error {
     NegentropyDeprecated(negentropy_deprecated::Error),
     /// Database error
     Database(DatabaseError),
-    /// Pool notification sender already set
-    PoolNotificationSenderAlreadySet,
     /// Generic timeout
     Timeout,
     /// Not replied to ping
@@ -130,9 +128,6 @@ impl fmt::Display for Error {
             Self::Negentropy(e) => write!(f, "{e}"),
             Self::NegentropyDeprecated(e) => write!(f, "{e}"),
             Self::Database(e) => write!(f, "{e}"),
-            Self::PoolNotificationSenderAlreadySet => {
-                write!(f, "pool notification sender already set")
-            }
             Self::Timeout => write!(f, "timeout"),
             Self::NotRepliedToPing => write!(f, "not replied to ping"),
             Self::CantParsePong => write!(f, "can't parse pong"),

crates/nostr-relay-pool/src/relay/inner.rs

@@ -8,7 +8,7 @@ use std::collections::{HashMap, HashSet};
 #[cfg(feature = "nip11")]
 use std::sync::atomic::AtomicU64;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::{Arc, OnceLock};
+use std::sync::Arc;
 use std::time::Duration;
 
 use async_utility::{task, time};
@@ -148,7 +148,7 @@ pub(crate) struct InnerRelay {
     pub(super) stats: RelayConnectionStats,
     pub(super) state: SharedState,
     pub(super) internal_notification_sender: broadcast::Sender<RelayNotification>,
-    external_notification_sender: OnceLock<broadcast::Sender<RelayPoolNotification>>,
+    external_notification_sender: Option<broadcast::Sender<RelayPoolNotification>>,
 }
 
 impl AtomicDestroyer for InnerRelay {
@@ -178,7 +178,7 @@ impl InnerRelay {
             stats: RelayConnectionStats::default(),
             state,
             internal_notification_sender: relay_notification_sender,
-            external_notification_sender: OnceLock::new(),
+            external_notification_sender: None,
         }
     }
 
@@ -359,16 +359,14 @@ impl InnerRelay {
     }
 
     pub(crate) fn set_notification_sender(
-        &self,
+        &mut self,
         notification_sender: broadcast::Sender<RelayPoolNotification>,
-    ) -> Result<(), Error> {
-        self.external_notification_sender
-            .set(notification_sender)
-            .map_err(|_| Error::PoolNotificationSenderAlreadySet)
+    ) {
+        self.external_notification_sender = Some(notification_sender);
     }
 
     fn send_notification(&self, notification: RelayNotification, external: bool) {
-        match (external, self.external_notification_sender.get()) {
+        match (external, &self.external_notification_sender) {
             (true, Some(external_notification_sender)) => {
                 // Clone and send internal notification
                 let _ = self.internal_notification_sender.send(notification.clone());