track weight for clear/removal

Author: camfairchild

pallets/subtensor/src/migration.rs

@@ -38,7 +38,11 @@ pub fn do_migrate_fix_total_coldkey_stake<T: Config>() -> Weight {
     let mut weight = T::DbWeight::get().reads(1);
 
     // Clear everything from the map first
-    let _ = TotalColdkeyStake::<T>::clear(u32::MAX, None);
+    let removal_results = TotalColdkeyStake::<T>::clear(u32::MAX, None);
+    // 1 read/write per removal
+    let entries_removed: u64 = removal_results.backend.into();
+    weight =
+        weight.saturating_add(T::DbWeight::get().reads_writes(entries_removed, entries_removed));
 
     // Iterate through all staking hotkeys.
     for (coldkey, hotkey_vec) in StakingHotkeys::<T>::iter() {