diff --git a/synapse/util/wheel_timer.py b/synapse/util/wheel_timer.py
index e108adc460..177e198e7e 100644
--- a/synapse/util/wheel_timer.py
+++ b/synapse/util/wheel_timer.py
@@ -11,17 +11,20 @@
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
-from typing import Generic, List, TypeVar
+import logging
+from typing import Generic, Hashable, List, Set, TypeVar
-T = TypeVar("T")
+import attr
+logger = logging.getLogger(__name__)
+
+T = TypeVar("T", bound=Hashable)
-class _Entry(Generic[T]):
- __slots__ = ["end_key", "queue"]
- def __init__(self, end_key: int) -> None:
- self.end_key: int = end_key
- self.queue: List[T] = []
+@attr.s(slots=True, frozen=True, auto_attribs=True)
+class _Entry(Generic[T]):
+ end_key: int
+ elements: Set[T] = attr.Factory(set)
class WheelTimer(Generic[T]):
@@ -48,17 +51,27 @@ class WheelTimer(Generic[T]):
then: When to return the object strictly after.
"""
then_key = int(then / self.bucket_size) + 1
+ now_key = int(now / self.bucket_size)
if self.entries:
min_key = self.entries[0].end_key
max_key = self.entries[-1].end_key
+ if min_key < now_key - 10:
+ # If we have ten buckets that are due and still nothing has
+ # called `fetch()` then we likely have a bug that is causing a
+ # memory leak.
+ logger.warning(
+ "Inserting into a wheel timer that hasn't been read from recently. Item: %s",
+ obj,
+ )
+
if then_key <= max_key:
# The max here is to protect against inserts for times in the past
- self.entries[max(min_key, then_key) - min_key].queue.append(obj)
+ self.entries[max(min_key, then_key) - min_key].elements.add(obj)
return
- next_key = int(now / self.bucket_size) + 1
+ next_key = now_key + 1
if self.entries:
last_key = self.entries[-1].end_key
else:
@@ -71,7 +84,7 @@ class WheelTimer(Generic[T]):
# to insert. This ensures there are no gaps.
self.entries.extend(_Entry(key) for key in range(last_key, then_key + 1))
- self.entries[-1].queue.append(obj)
+ self.entries[-1].elements.add(obj)
def fetch(self, now: int) -> List[T]:
"""Fetch any objects that have timed out
@@ -84,11 +97,11 @@ class WheelTimer(Generic[T]):
"""
now_key = int(now / self.bucket_size)
- ret = []
+ ret: List[T] = []
while self.entries and self.entries[0].end_key <= now_key:
- ret.extend(self.entries.pop(0).queue)
+ ret.extend(self.entries.pop(0).elements)
return ret
def __len__(self) -> int:
- return sum(len(entry.queue) for entry in self.entries)
+ return sum(len(entry.elements) for entry in self.entries)
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