Merge pull request #50 from CirclesUBI/update-predict-address

Avoid predicting a new address if there's already one registered

safe_relay_service/relay/services/safe_creation_service.py

@@ -153,6 +153,25 @@ def _check_safe_balance(self, safe_creation2: SafeCreation2) -> NoReturn:
             logger.info('Found %d balance for safe=%s with payment-token=%s. Required=%d', safe_balance,
                         safe_address, safe_creation2.payment_token, safe_creation2.payment)
 
+    def existing_predicted_address(self, salt_nonce: int, owners: Iterable[str]) -> str:
+        """
+        Return a previously predicted Safe address.
+        Note that the prediction parameters are not updated for the SafeCreation2 object
+        :param salt_nonce: Random value for solidity `create2` salt
+        :param owners: Owners of the new Safe
+        :rtype: str
+        """
+        try:
+            # The salt_nonce is deterministicly generated from the owner address
+            safe_creation = SafeCreation2.objects.filter(owners__contains=owners, salt_nonce=salt_nonce).order_by('created').first()
+            if not safe_creation:
+                return NULL_ADDRESS
+            logger.info('The relayer had already predicted an address for this owner. Safe addr: %s, owner: %s', safe_creation.safe_id, owners)
+            return safe_creation.safe_id
+        except SafeCreation2.DoesNotExist:
+            return NULL_ADDRESS
+
+
     def predict_address(self, salt_nonce: int, owners: Iterable[str], threshold: int,
                         payment_token: Optional[str]) -> str:
         """

safe_relay_service/relay/views_v3.py

@@ -50,7 +50,8 @@ class SafeAddressPredictionView(CreateAPIView):
                                     422: 'Cannot process data'})
     def post(self, request, *args, **kwargs):
         """
-        Predicts the safe address
+        Predicts the safe address. If the relayer already predicted an address for that owner, it doesn't do the prediction again.
+        Note that the prediction parameters are not updated for the SafeCreation2 object
         """
         serializer = self.serializer_class(data=request.data)
         if serializer.is_valid():
@@ -59,7 +60,9 @@ def post(self, request, *args, **kwargs):
                                                             serializer.data['payment_token'])
 
             safe_creation_service = SafeCreationServiceProvider()
-            safe_prediction = safe_creation_service.predict_address(salt_nonce, owners, threshold, payment_token)
+            safe_prediction = safe_creation_service.existing_predicted_address(salt_nonce, owners)
+            if safe_prediction == NULL_ADDRESS:
+                safe_prediction = safe_creation_service.predict_address(salt_nonce, owners, threshold, payment_token)
             safe_prediction_response_data = SafeAddressPredictionResponseSerializer(data={
                 'safe': safe_prediction,
             })