Add additional_rate_limit argument

Resolves #73

docs/changelog.rst

@@ -4,6 +4,12 @@ Change Log
 Unreleased_
 -----------
 
+Added
+~~~~~
+
+- ``additional_rate_limit`` argument to
+  :class:`~spacetrack.base.SpaceTrackClient`.
+
 Fixed
 ~~~~~
 

src/spacetrack/aio.py

@@ -37,6 +37,7 @@ def __init__(
         rush_store=None,
         rush_key_prefix="",
         httpx_client=None,
+        additional_rate_limit=None,
     ):
         if httpx_client is None:
             httpx_client = httpx.AsyncClient()
@@ -49,6 +50,7 @@ def __init__(
             rush_store=rush_store,
             rush_key_prefix=rush_key_prefix,
             httpx_client=httpx_client,
+            additional_rate_limit=additional_rate_limit,
         )
 
     async def _handle_event(self, event):

src/spacetrack/base.py

@@ -140,6 +140,8 @@ class SpaceTrackClient:
             ``SpaceTrackClient`` takes ownership of the httpx client. You should
             only provide your own client if you need to configure it first (e.g.
             for a proxy).
+        additional_rate_limit: Optionally, a :class:`rush.quota.Quota` if you
+            want to restrict the rate limit further than the defaults.
 
     For more information, refer to the `Space-Track documentation`_.
 
@@ -268,6 +270,7 @@ def __init__(
         rush_store=None,
         rush_key_prefix="",
         httpx_client=None,
+        additional_rate_limit=None,
     ):
         if httpx_client is None:
             httpx_client = httpx.Client()
@@ -303,6 +306,15 @@ def __init__(
         )
         self._per_minute_key = rush_key_prefix + "st_req_min"
         self._per_hour_key = rush_key_prefix + "st_req_hr"
+        self._additional_key = rush_key_prefix + "st_req_custom"
+        if isinstance(additional_rate_limit, Quota):
+            self._additional_throttle = Throttle(
+                limiter=limiter, rate=additional_rate_limit
+            )
+        elif additional_rate_limit is None:
+            self._additional_throttle = None
+        else:
+            raise TypeError("additional_rate_limit must be a rush.quota.Quota")
 
     @property
     def base_url(self):
@@ -600,6 +612,10 @@ def _ratelimited_send_generator(self, request, *, stream=False):
         if hour_limit.limited:
             sleep_time = max(sleep_time, hour_limit.retry_after.total_seconds())
 
+        if self._additional_throttle is not None:
+            additional_limit = self._additional_throttle.check(self._additional_key, 1)
+            sleep_time = max(sleep_time, additional_limit.retry_after.total_seconds())
+
         if sleep_time > 0:
             yield RateLimitWait(sleep_time)