feat: add reorg metrics (#3824)

crates/blockchain-tree/src/blockchain_tree.rs

@@ -1003,6 +1003,7 @@ impl<DB: Database, C: Consensus, EF: ExecutorFactory> BlockchainTree<DB, C, EF>
                 };
                 // insert old canon chain
                 self.insert_chain(AppendableChain::new(old_canon_chain));
+                self.metrics.reorgs.increment(1);
             } else {
                 // error here to confirm that we are reverting nothing from db.
                 error!(target: "blockchain_tree", "Reverting nothing from db on block: #{:?}", block_hash);

crates/blockchain-tree/src/metrics.rs

@@ -1,5 +1,5 @@
 use reth_metrics::{
-    metrics::{self, Gauge},
+    metrics::{self, Counter, Gauge},
     Metrics,
 };
 
@@ -11,6 +11,8 @@ pub struct TreeMetrics {
     pub sidechains: Gauge,
     /// The highest block number in the canonical chain
     pub canonical_chain_height: Gauge,
+    /// The number of reorgs
+    pub reorgs: Counter,
 }
 
 /// Metrics for the blockchain tree block buffer