chore: ensure sub before adding to LRU cache

Author: thlorenz

magicblock-chainlink/src/remote_account_provider/lru_cache.rs

@@ -128,6 +128,10 @@ impl AccountsLruCache {
         self.accounts_to_never_evict.iter().cloned().collect()
     }
 
+    pub fn can_evict(&self, pubkey: &Pubkey) -> bool {
+        !self.accounts_to_never_evict.contains(pubkey)
+    }
+
     pub fn pubkeys(&self) -> Vec<Pubkey> {
         let subs = self
             .subscribed_accounts

magicblock-chainlink/src/remote_account_provider/mod.rs

@@ -732,31 +732,28 @@ impl<T: ChainRpcClient, U: ChainPubsubClient> RemoteAccountProvider<T, U> {
         &self,
         pubkey: &Pubkey,
     ) -> RemoteAccountProviderResult<()> {
-        // If an account is evicted then we need to unsubscribe from it first
+        // 1. First realize subscription
+        if let Err(err) = self.pubsub_client.subscribe(*pubkey).await {
+            return Err(err);
+        }
+
+        // 2. Add to LRU cache
+        // If an account is evicted then we need to unsubscribe from it
         // and then inform upstream that we are no longer tracking it
         if let Some(evicted) = self.lrucache_subscribed_accounts.add(*pubkey) {
             trace!("Evicting {pubkey}");
 
             // 1. Unsubscribe from the account directly (LRU has already removed it)
             if let Err(err) = self.pubsub_client.unsubscribe(evicted).await {
+                // Should we retry here?
                 warn!(
                     "Failed to unsubscribe from pubsub for evicted account {evicted}: {err:?}");
-                // Rollback the LRU add since eviction failed
-                self.lrucache_subscribed_accounts.remove(pubkey);
-                return Err(err);
             }
 
             // 2. Inform upstream so it can remove it from the store
             self.send_removal_update(evicted).await?;
         }
 
-        // 3. Subscribe to the new account (only after successful eviction handling)
-        if let Err(err) = self.pubsub_client.subscribe(*pubkey).await {
-            // Rollback the LRU add since subscription failed
-            self.lrucache_subscribed_accounts.remove(pubkey);
-            return Err(err);
-        }
-
         Ok(())
     }
 
@@ -803,6 +800,13 @@ impl<T: ChainRpcClient, U: ChainPubsubClient> RemoteAccountProvider<T, U> {
         &self,
         pubkey: &Pubkey,
     ) -> RemoteAccountProviderResult<()> {
+        if !self.lrucache_subscribed_accounts.can_evict(pubkey) {
+            warn!(
+                "Tried to unsubscribe from account {} that should never be evicted",
+                pubkey
+            );
+            return Ok(());
+        }
         if !self.lrucache_subscribed_accounts.contains(pubkey) {
             warn!(
                 "Tried to unsubscribe from account {} that was not subscribed in the LRU cache",