migrate to mutate_exist

Author: ferrell-code

rewards/src/lib.rs

@@ -130,28 +130,33 @@ impl<T: Config> Pallet<T> {
 		// claim rewards firstly
 		Self::claim_rewards(who, pool);
 
-		ShareAndWithdrawnReward::<T>::mutate(pool, who, |(share, withdrawn_rewards)| {
-			let remove_amount = remove_amount.min(*share);
+		ShareAndWithdrawnReward::<T>::mutate_exists(pool, who, |share_info| {
+			if let Some((mut share, mut withdrawn_rewards)) = share_info.take() {
+				let remove_amount = remove_amount.min(share);
 
-			if remove_amount.is_zero() {
-				return;
-			}
+				if remove_amount.is_zero() {
+					return;
+				}
 
-			Pools::<T>::mutate(pool, |pool_info| {
-				let proportion = FixedU128::checked_from_rational(remove_amount, *share)
-					.expect("share is gte remove_amount and not zero which checked before; qed");
-				let withdrawn_rewards_to_remove = proportion.saturating_mul_int(*withdrawn_rewards);
+				Pools::<T>::mutate(pool, |pool_info| {
+					let proportion = FixedU128::checked_from_rational(remove_amount, share)
+						.expect("share is gte remove_amount and not zero which checked before; qed");
+					let withdrawn_rewards_to_remove = proportion.saturating_mul_int(withdrawn_rewards);
 
-				pool_info.total_shares = pool_info.total_shares.saturating_sub(remove_amount);
-				pool_info.total_rewards = pool_info.total_rewards.saturating_sub(withdrawn_rewards_to_remove);
-				pool_info.total_withdrawn_rewards = pool_info
-					.total_withdrawn_rewards
-					.saturating_sub(withdrawn_rewards_to_remove);
+					pool_info.total_shares = pool_info.total_shares.saturating_sub(remove_amount);
+					pool_info.total_rewards = pool_info.total_rewards.saturating_sub(withdrawn_rewards_to_remove);
+					pool_info.total_withdrawn_rewards = pool_info
+						.total_withdrawn_rewards
+						.saturating_sub(withdrawn_rewards_to_remove);
 
-				*withdrawn_rewards = withdrawn_rewards.saturating_sub(withdrawn_rewards_to_remove);
-			});
+					withdrawn_rewards = withdrawn_rewards.saturating_sub(withdrawn_rewards_to_remove);
+				});
 
-			*share = share.saturating_sub(remove_amount);
+				share = share.saturating_sub(remove_amount);
+				if share != Zero::zero() {
+					*share_info = Some((share, withdrawn_rewards));
+				}
+			}
 		});
 	}