fix: avoid retaining uncled blocks

graph-gateway/src/chains/mod.rs

@@ -187,11 +187,17 @@ impl Actor {
             }
         }
 
-        self.handle_block(head.block.clone()).await;
-
         let blocks_per_minute = self.block_rate_estimator.update(head.block.number);
         self.blocks_per_minute_tx.write(blocks_per_minute);
 
+        // Remove prior blocks from the past minute. This avoids retaining uncled blocks that are
+        // frequently used.
+        let cutoff = head.block.number - blocks_per_minute;
+        self.number_to_hash.retain(|n, _| *n < cutoff);
+        self.hash_to_number.retain(|_, n| *n < cutoff);
+
+        self.handle_block(head.block.clone()).await;
+
         with_metric(&METRICS.chain_head, &[&self.chain], |g| {
             g.set(head.block.number as i64)
         });

prelude/src/epoch_cache.rs

@@ -82,6 +82,13 @@ impl<K: Eq + Hash, V, const C: u8> EpochCache<K, V, C> {
             f(v);
         }
     }
+
+    pub fn retain<F>(&mut self, mut f: F)
+    where
+        F: FnMut(&K, &mut V) -> bool,
+    {
+        self.0.retain(|k, (v, _)| f(k, v));
+    }
 }
 
 #[cfg(test)]