feat(client): adjust retry behavior to be exponential backoff (#149)

Author: stainless-bot

src/finch/_base_client.py

@@ -158,7 +158,7 @@ class BasePage(GenericModel, Generic[ModelT]):
 
     Methods:
         has_next_page(): Check if there is another page available
-        next_page_info(): Get the necesary information to make a request for the next page
+        next_page_info(): Get the necessary information to make a request for the next page
     """
 
     _options: FinalRequestOptions = PrivateAttr()
@@ -691,15 +691,15 @@ def _calculate_retry_timeout(
             return retry_after
 
         initial_retry_delay = 0.5
-        max_retry_delay = 2.0
+        max_retry_delay = 8.0
         nb_retries = max_retries - remaining_retries
 
         # Apply exponential backoff, but not more than the max.
-        sleep_seconds = min(initial_retry_delay * pow(nb_retries - 1, 2), max_retry_delay)
+        sleep_seconds = min(initial_retry_delay * pow(2.0, nb_retries), max_retry_delay)
 
         # Apply some jitter, plus-or-minus half a second.
-        jitter = random() - 0.5
-        timeout = sleep_seconds + jitter
+        jitter = 1 - 0.25 * random()
+        timeout = sleep_seconds * jitter
         return timeout if timeout >= 0 else 0
 
     def _should_retry(self, response: httpx.Response) -> bool:

tests/test_client.py

@@ -639,28 +639,30 @@ class Model(BaseModel):
         "remaining_retries,retry_after,timeout",
         [
             [3, "20", 20],
-            [3, "0", 2],
-            [3, "-10", 2],
+            [3, "0", 0.5],
+            [3, "-10", 0.5],
             [3, "60", 60],
-            [3, "61", 2],
+            [3, "61", 0.5],
             [3, "Fri, 29 Sep 2023 16:26:57 GMT", 20],
-            [3, "Fri, 29 Sep 2023 16:26:37 GMT", 2],
-            [3, "Fri, 29 Sep 2023 16:26:27 GMT", 2],
+            [3, "Fri, 29 Sep 2023 16:26:37 GMT", 0.5],
+            [3, "Fri, 29 Sep 2023 16:26:27 GMT", 0.5],
             [3, "Fri, 29 Sep 2023 16:27:37 GMT", 60],
-            [3, "Fri, 29 Sep 2023 16:27:38 GMT", 2],
-            [3, "99999999999999999999999999999999999", 2],
-            [3, "Zun, 29 Sep 2023 16:26:27 GMT", 2],
-            [3, "", 2],
+            [3, "Fri, 29 Sep 2023 16:27:38 GMT", 0.5],
+            [3, "99999999999999999999999999999999999", 0.5],
+            [3, "Zun, 29 Sep 2023 16:26:27 GMT", 0.5],
+            [3, "", 0.5],
+            [2, "", 0.5 * 2.0],
+            [1, "", 0.5 * 4.0],
         ],
     )
     @mock.patch("time.time", mock.MagicMock(return_value=1696004797))
     def test_parse_retry_after_header(self, remaining_retries: int, retry_after: str, timeout: float) -> None:
         client = Finch(base_url=base_url, access_token=access_token, _strict_response_validation=True)
 
         headers = httpx.Headers({"retry-after": retry_after})
-        options = FinalRequestOptions(method="get", url="/foo", max_retries=2)
+        options = FinalRequestOptions(method="get", url="/foo", max_retries=3)
         calculated = client._calculate_retry_timeout(remaining_retries, options, headers)
-        assert calculated == pytest.approx(timeout, 0.6)  # pyright: ignore[reportUnknownMemberType]
+        assert calculated == pytest.approx(timeout, 0.5 * 0.875)  # pyright: ignore[reportUnknownMemberType]
 
 
 class TestAsyncFinch:
@@ -1272,18 +1274,20 @@ class Model(BaseModel):
         "remaining_retries,retry_after,timeout",
         [
             [3, "20", 20],
-            [3, "0", 2],
-            [3, "-10", 2],
+            [3, "0", 0.5],
+            [3, "-10", 0.5],
             [3, "60", 60],
-            [3, "61", 2],
+            [3, "61", 0.5],
             [3, "Fri, 29 Sep 2023 16:26:57 GMT", 20],
-            [3, "Fri, 29 Sep 2023 16:26:37 GMT", 2],
-            [3, "Fri, 29 Sep 2023 16:26:27 GMT", 2],
+            [3, "Fri, 29 Sep 2023 16:26:37 GMT", 0.5],
+            [3, "Fri, 29 Sep 2023 16:26:27 GMT", 0.5],
             [3, "Fri, 29 Sep 2023 16:27:37 GMT", 60],
-            [3, "Fri, 29 Sep 2023 16:27:38 GMT", 2],
-            [3, "99999999999999999999999999999999999", 2],
-            [3, "Zun, 29 Sep 2023 16:26:27 GMT", 2],
-            [3, "", 2],
+            [3, "Fri, 29 Sep 2023 16:27:38 GMT", 0.5],
+            [3, "99999999999999999999999999999999999", 0.5],
+            [3, "Zun, 29 Sep 2023 16:26:27 GMT", 0.5],
+            [3, "", 0.5],
+            [2, "", 0.5 * 2.0],
+            [1, "", 0.5 * 4.0],
         ],
     )
     @mock.patch("time.time", mock.MagicMock(return_value=1696004797))
@@ -1292,6 +1296,6 @@ async def test_parse_retry_after_header(self, remaining_retries: int, retry_afte
         client = AsyncFinch(base_url=base_url, access_token=access_token, _strict_response_validation=True)
 
         headers = httpx.Headers({"retry-after": retry_after})
-        options = FinalRequestOptions(method="get", url="/foo", max_retries=2)
+        options = FinalRequestOptions(method="get", url="/foo", max_retries=3)
         calculated = client._calculate_retry_timeout(remaining_retries, options, headers)
-        assert calculated == pytest.approx(timeout, 0.6)  # pyright: ignore[reportUnknownMemberType]
+        assert calculated == pytest.approx(timeout, 0.5 * 0.875)  # pyright: ignore[reportUnknownMemberType]