Add mechanism to get blockhash's last valid slot (#10239)

automerge

runtime/src/bank.rs

@@ -936,6 +936,15 @@ impl Bank {
         &self.fee_rate_governor
     }
 
+    pub fn get_blockhash_last_valid_slot(&self, blockhash: &Hash) -> Option<Slot> {
+        let blockhash_queue = self.blockhash_queue.read().unwrap();
+        // This calculation will need to be updated to consider epoch boundaries if BlockhashQueue
+        // length is made variable by epoch
+        blockhash_queue
+            .get_hash_age(blockhash)
+            .map(|age| self.slot + blockhash_queue.len() as u64 - age)
+    }
+
     pub fn confirmed_last_blockhash(&self) -> (Hash, FeeCalculator) {
         const NUM_BLOCKHASH_CONFIRMATIONS: usize = 3;
 

runtime/src/blockhash_queue.rs

@@ -58,6 +58,12 @@ impl BlockhashQueue {
             .map(|age| self.hash_height - age.hash_height <= max_age as u64)
     }
 
+    pub fn get_hash_age(&self, hash: &Hash) -> Option<u64> {
+        self.ages
+            .get(hash)
+            .map(|age| self.hash_height - age.hash_height)
+    }
+
     /// check if hash is valid
     #[cfg(test)]
     pub fn check_hash(&self, hash: Hash) -> bool {
@@ -119,6 +125,10 @@ impl BlockhashQueue {
             .iter()
             .map(|(k, v)| recent_blockhashes::IterItem(v.hash_height, k, &v.fee_calculator))
     }
+
+    pub fn len(&self) -> usize {
+        self.max_age
+    }
 }
 #[cfg(test)]
 mod tests {