Blockstore: only return block times for rooted slots (solana-labs#33871)

* Add Blockstore::get_rooted_block_time method and use in RPC

* Un-pub get_block_time

ledger/src/blockstore.rs

@@ -1962,12 +1962,23 @@ impl Blockstore {
         }
     }
 
-    pub fn get_block_time(&self, slot: Slot) -> Result<Option<UnixTimestamp>> {
-        datapoint_info!("blockstore-rpc-api", ("method", "get_block_time", String));
+    fn get_block_time(&self, slot: Slot) -> Result<Option<UnixTimestamp>> {
         let _lock = self.check_lowest_cleanup_slot(slot)?;
         self.blocktime_cf.get(slot)
     }
 
+    pub fn get_rooted_block_time(&self, slot: Slot) -> Result<Option<UnixTimestamp>> {
+        datapoint_info!(
+            "blockstore-rpc-api",
+            ("method", "get_rooted_block_time", String)
+        );
+        let _lock = self.check_lowest_cleanup_slot(slot)?;
+        if self.is_root(slot) {
+            return self.blocktime_cf.get(slot);
+        }
+        Err(BlockstoreError::SlotNotRooted)
+    }
+
     pub fn cache_block_time(&self, slot: Slot, timestamp: UnixTimestamp) -> Result<()> {
         self.blocktime_cf.put(slot, &timestamp)
     }

rpc/src/rpc.rs

@@ -1321,7 +1321,7 @@ impl JsonRpcRequestProcessor {
                 .unwrap()
                 .highest_super_majority_root()
         {
-            let result = self.blockstore.get_block_time(slot);
+            let result = self.blockstore.get_rooted_block_time(slot);
             self.check_blockstore_root(&result, slot)?;
             if result.is_err() || matches!(result, Ok(None)) {
                 if let Some(bigtable_ledger_storage) = &self.bigtable_ledger_storage {