Export RatelimitOverride from ModuleApi (element-hq#18513)

Author: hughns

changelog.d/18513.bugfix

@@ -0,0 +1 @@
+Support the import of the `RatelimitOverride` type from `synapse.module_api` in modules and rename `messages_per_second` to `per_second`.

docs/modules/ratelimit_callbacks.md

@@ -11,7 +11,7 @@ The available ratelimit callbacks are:
 _First introduced in Synapse v1.132.0_
 
 ```python
-async def get_ratelimit_override_for_user(user: str, limiter_name: str) -> Optional[RatelimitOverride]
+async def get_ratelimit_override_for_user(user: str, limiter_name: str) -> Optional[synapse.module_api.RatelimitOverride]
 ```
 
 Called when constructing a ratelimiter of a particular type for a user. The module can
@@ -26,6 +26,11 @@ The limiters that are currently supported are:
 - `rc_invites.per_user`
 - `rc_invites.per_issuer`
 
+The `RatelimitOverride` return type has the following fields:
+
+- `per_second: float`. The number of actions that can be performed in a second. `0.0` means that ratelimiting is disabled.
+- `burst_count: int`. The number of actions that can be performed before being limited.
+
 If multiple modules implement this callback, they will be considered in order. If a
 callback returns `None`, Synapse falls through to the next one. The value of the first
 callback that does not return `None` will be used. If this happens, Synapse will not call

synapse/api/ratelimiting.py

@@ -184,7 +184,7 @@ async def can_do_action(
             )
 
             if module_override:
-                rate_hz = module_override.messages_per_second
+                rate_hz = module_override.per_second
                 burst_count = module_override.burst_count
 
         # Override default values if set

synapse/module_api/__init__.py

@@ -96,6 +96,7 @@
 )
 from synapse.module_api.callbacks.ratelimit_callbacks import (
     GET_RATELIMIT_OVERRIDE_FOR_USER_CALLBACK,
+    RatelimitOverride,
 )
 from synapse.module_api.callbacks.spamchecker_callbacks import (
     CHECK_EVENT_FOR_SPAM_CALLBACK,
@@ -197,6 +198,7 @@
     "ProfileInfo",
     "RoomAlias",
     "UserProfile",
+    "RatelimitOverride",
 ]
 
 logger = logging.getLogger(__name__)

synapse/module_api/callbacks/ratelimit_callbacks.py

@@ -15,7 +15,8 @@
 import logging
 from typing import TYPE_CHECKING, Awaitable, Callable, List, Optional
 
-from synapse.storage.databases.main.room import RatelimitOverride
+import attr
+
 from synapse.util.async_helpers import delay_cancellation
 from synapse.util.metrics import Measure
 
@@ -24,6 +25,17 @@
 
 logger = logging.getLogger(__name__)
 
+
+@attr.s(auto_attribs=True)
+class RatelimitOverride:
+    """Represents a ratelimit being overridden."""
+
+    per_second: float
+    """The number of actions that can be performed in a second. `0.0` means that ratelimiting is disabled."""
+    burst_count: int
+    """How many actions that can be performed before being limited."""
+
+
 GET_RATELIMIT_OVERRIDE_FOR_USER_CALLBACK = Callable[
     [str, str], Awaitable[Optional[RatelimitOverride]]
 ]

synapse/storage/databases/main/room.py

@@ -77,7 +77,9 @@
 
 @attr.s(slots=True, frozen=True, auto_attribs=True)
 class RatelimitOverride:
-    messages_per_second: float
+    # n.b. elsewhere in Synapse messages_per_second is represented as a float, but it is
+    # an integer in the database
+    messages_per_second: int
     burst_count: int
 
 

tests/api/test_ratelimiting.py

@@ -3,8 +3,8 @@
 from synapse.api.ratelimiting import LimitExceededError, Ratelimiter
 from synapse.appservice import ApplicationService
 from synapse.config.ratelimiting import RatelimitSettings
+from synapse.module_api import RatelimitOverride
 from synapse.module_api.callbacks.ratelimit_callbacks import RatelimitModuleApiCallbacks
-from synapse.storage.databases.main.room import RatelimitOverride
 from synapse.types import create_requester
 
 from tests import unittest
@@ -477,7 +477,7 @@ async def get_ratelimit_override_for_user(
         ) -> Optional[RatelimitOverride]:
             if user_id == test_user_id:
                 return RatelimitOverride(
-                    messages_per_second=0.1,
+                    per_second=0.1,
                     burst_count=10,
                 )
             return None