Add caching on client id for purchases

src/purchase/tests/test_send_rsc.py

@@ -45,7 +45,7 @@ def test_list_purchases(self):
         )
 
         response = self._post_support_response(
-            purchaser, post.id, "researchhubpost", tip_amount
+            purchaser, post.id, "client_id_1", "researchhubpost", tip_amount
         )
         self.assertContains(response, "id", status_code=201)
 
@@ -68,7 +68,7 @@ def test_list_purchases_cannot_list_other_users_purchases(self):
         )
 
         response = self._post_support_response(
-            purchaser, post.id, "researchhubpost", tip_amount
+            purchaser, post.id, "client_id_2", "researchhubpost", tip_amount
         )
         self.assertContains(response, "id", status_code=201)
 
@@ -125,7 +125,9 @@ def test_support_paper_distribution(self):
             amount="10000", user=user, content_type=DISTRIBUTION_CONTENT_TYPE
         )
 
-        response = self._post_support_response(user, paper.id, "paper", amount)
+        response = self._post_support_response(
+            user, paper.id, "client_id_3", "paper", amount
+        )
         self.assertContains(response, "id", status_code=201)
         self.assertTrue(Escrow.objects.filter(hold_type=Escrow.AUTHOR_RSC).count() == 1)
         author_pot = Escrow.objects.filter(hold_type=Escrow.AUTHOR_RSC).first()
@@ -146,7 +148,7 @@ def test_support_post_distribution(self):
         )
 
         response = self._post_support_response(
-            user, post.id, "researchhubpost", tip_amount
+            user, post.id, "client_id_4", "researchhubpost", tip_amount
         )
         self.assertContains(response, "id", status_code=201)
         purchase_id = response.data["id"]
@@ -193,7 +195,7 @@ def test_support_comment_distribution(self):
         )
 
         response = self._post_support_response(
-            user, comment.id, "rhcommentmodel", tip_amount
+            user, comment.id, "client_id_5", "rhcommentmodel", tip_amount
         )
         self.assertContains(response, "id", status_code=201)
         purchase_id = response.data["id"]
@@ -224,7 +226,36 @@ def test_support_comment_distribution(self):
         )
         self.assertEqual(poster_balance_amount, float(tip_amount))
 
-    def _post_support_response(self, user, object_id, content_type, amount=10):
+    def test_repeat_request_support_comment_distribution(self):
+        user = create_random_authenticated_user("rep_user")
+        poster = create_random_authenticated_user("rep_user")
+        post = create_post(created_by=poster)
+        comment = create_rh_comment(created_by=poster, post=post)
+        client_id = "client_id_6"
+
+        tip_amount = 100
+
+        # give the user 10,000 RSC
+        DISTRIBUTION_CONTENT_TYPE = ContentType.objects.get(model="distribution")
+        Balance.objects.create(
+            amount="10000", user=user, content_type=DISTRIBUTION_CONTENT_TYPE
+        )
+
+        response = self._post_support_response(
+            user, comment.id, client_id, "rhcommentmodel", tip_amount
+        )
+        self.assertContains(response, "id", status_code=201)
+
+        # make a second request with the same client_id which should fail.
+        response_repeat_call = self._post_support_response(
+            user, comment.id, client_id, "rhcommentmodel", tip_amount
+        )
+        self.assertEqual(response.data, response_repeat_call.data)
+        self.assertEqual(response_repeat_call.status_code, 201)
+
+    def _post_support_response(
+        self, user, object_id, client_id, content_type, amount=10
+    ):
         url = "/api/purchase/"
         return get_authenticated_post_response(
             user,
@@ -235,5 +266,6 @@ def _post_support_response(self, user, object_id, content_type, amount=10):
                 "object_id": object_id,
                 "purchase_method": "OFF_CHAIN",
                 "purchase_type": "BOOST",
+                "client_id": client_id,
             },
         )

src/purchase/views/purchase_view.py

@@ -56,6 +56,7 @@ def create(self, request):
         data = request.data
 
         amount = data["amount"]
+        client_id = data["client_id"]
         purchase_method = data["purchase_method"]
         purchase_type = data["purchase_type"]
         content_type_str = data["content_type"]
@@ -77,6 +78,13 @@ def create(self, request):
         with transaction.atomic():
             user = User.objects.select_for_update().get(id=user.id)
 
+            cached_serialized_data = cache.get(f"purchase_client_id_{client_id}")
+            if cached_serialized_data:
+                return Response(
+                    cached_serialized_data,
+                    status=201,
+                )
+
             purchase_data = {
                 "amount": amount,
                 "user": user.id,
@@ -204,8 +212,10 @@ def create(self, request):
                 )
                 distributor.distribute()
 
-        serializer = self.serializer_class(purchase, context=context)
-        serializer_data = serializer.data
+            serializer = self.serializer_class(purchase, context=context)
+            serializer_data = serializer.data
+
+            cache.set(f"purchase_client_id_{client_id}", serializer_data, timeout=3600)
 
         if recipient and user:
             self.send_purchase_notification(