f make the queue LRU

Author: TheBlueMatt

lightning-block-sync/src/gossip.rs

@@ -209,11 +209,14 @@ impl<S: FutureSpawner,
 			}
 			{
 				let recent_blocks = block_cache.lock().unwrap();
-				for (height, block) in recent_blocks.iter() {
-					if *height == block_height {
-						process_block!(block);
-						break 'tx_found;
+				let pos_opt = recent_blocks.iter().position(|(height, _)| *height == block_height);
+				if let Some(pos) = pos_opt {
+					if pos != recent_blocks.len() - 1 {
+						// Push the block to the end of the LRU queue
+						core::mem::swap(&mut recent_blocks.last_mut().unwrap(), &mut recent_blocks[pos]);
 					}
+					process_block!(recent_blocks.last().unwrap().1);
+					break 'tx_found;
 				}
 			}