slight simplification to get_min_fee_rate() (#17092)

chia/full_node/mempool.py

@@ -184,32 +184,33 @@ class Mempool:
                 items.extend(self._row_to_item(row) for row in cursor)
         return items
 
-    def get_min_fee_rate(self, cost: int) -> float:
+    def get_min_fee_rate(self, cost: int) -> Optional[float]:
         """
         Gets the minimum fpc rate that a transaction with specified cost will need in order to get included.
         """
 
-        if self.at_full_capacity(cost):
-            # TODO: make MempoolItem.cost be CLVMCost
-            current_cost = int(self.total_mempool_cost())
+        if not self.at_full_capacity(cost):
+            return 0
 
-            # Iterates through all spends in increasing fee per cost
-            with self._db_conn:
-                cursor = self._db_conn.execute("SELECT cost,fee_per_cost FROM tx ORDER BY fee_per_cost ASC, seq DESC")
+        # TODO: make MempoolItem.cost be CLVMCost
+        current_cost = int(self.total_mempool_cost())
 
-                item_cost: int
-                fee_per_cost: float
-                for item_cost, fee_per_cost in cursor:
-                    current_cost -= item_cost
-                    # Removing one at a time, until our transaction of size cost fits
-                    if current_cost + cost <= self.mempool_info.max_size_in_cost:
-                        return fee_per_cost
+        # Iterates through all spends in increasing fee per cost
+        with self._db_conn:
+            cursor = self._db_conn.execute("SELECT cost,fee_per_cost FROM tx ORDER BY fee_per_cost ASC, seq DESC")
 
-            raise ValueError(
+            item_cost: int
+            fee_per_cost: float
+            for item_cost, fee_per_cost in cursor:
+                current_cost -= item_cost
+                # Removing one at a time, until our transaction of size cost fits
+                if current_cost + cost <= self.mempool_info.max_size_in_cost:
+                    return fee_per_cost
+
+            log.info(
                 f"Transaction with cost {cost} does not fit in mempool of max cost {self.mempool_info.max_size_in_cost}"
             )
-        else:
-            return 0
+            return None
 
     def new_tx_block(self, block_height: uint32, timestamp: uint64) -> None:
         """

chia/full_node/mempool_manager.py

@@ -244,11 +244,12 @@ class MempoolManager:
         if cost == 0:
             return False
         fees_per_cost = fees / cost
-        if not self.mempool.at_full_capacity(cost) or (
-            fees_per_cost >= self.nonzero_fee_minimum_fpc and fees_per_cost > self.mempool.get_min_fee_rate(cost)
-        ):
+        if not self.mempool.at_full_capacity(cost):
             return True
-        return False
+        if fees_per_cost < self.nonzero_fee_minimum_fpc:
+            return False
+        min_fee_rate = self.mempool.get_min_fee_rate(cost)
+        return min_fee_rate is not None and fees_per_cost > min_fee_rate
 
     def add_and_maybe_pop_seen(self, spend_name: bytes32) -> None:
         self.seen_bundle_hashes[spend_name] = spend_name
@@ -465,8 +466,12 @@ class MempoolManager:
         if self.mempool.at_full_capacity(cost):
             if fees_per_cost < self.nonzero_fee_minimum_fpc:
                 return Err.INVALID_FEE_TOO_CLOSE_TO_ZERO, None, []
-            if fees_per_cost <= self.mempool.get_min_fee_rate(cost):
+            min_fee_rate = self.mempool.get_min_fee_rate(cost)
+            if min_fee_rate is None:
+                return Err.INVALID_COST_RESULT, None, []
+            if fees_per_cost <= min_fee_rate:
                 return Err.INVALID_FEE_LOW_FEE, None, []
+
         # Check removals against UnspentDB + DiffStore + Mempool + SpendBundle
         # Use this information later when constructing a block
         fail_reason, conflicts = self.check_removals(non_eligible_coin_ids, removal_record_dict)

tests/core/mempool/test_mempool.py

@@ -310,8 +310,7 @@ class TestMempool:
         mempool = Mempool(mempool_info, fee_estimator)
         assert mempool.get_min_fee_rate(104000) == 0
 
-        with pytest.raises(ValueError):
-            mempool.get_min_fee_rate(max_mempool_cost + 1)
+        assert mempool.get_min_fee_rate(max_mempool_cost + 1) is None
 
         coin = await next_block(full_node_1, wallet_a, bt)
         spend_bundle = generate_test_spend_bundle(wallet_a, coin)