Add wheeltimer impl
1 files changed, 88 insertions, 0 deletions
diff --git a/synapse/util/wheel_timer.py b/synapse/util/wheel_timer.py
new file mode 100644
index 0000000000..b447b2456c
--- /dev/null
+++ b/synapse/util/wheel_timer.py
@@ -0,0 +1,88 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+
+
+class _Entry(object):
+ __slots__ = ["end_key", "queue"]
+
+ def __init__(self, end_key):
+ self.end_key = end_key
+ self.queue = []
+
+
+class WheelTimer(object):
+ """Stores arbitrary objects that will be returned after their timers have
+ expired.
+ """
+
+ def __init__(self, bucket_size=5000):
+ """
+ Args:
+ bucket_size (int): Size of buckets in ms. Corresponds roughly to the
+ accuracy of the timer.
+ """
+ self.bucket_size = bucket_size
+ self.entries = []
+ self.current_tick = 0
+
+ def insert(self, now, obj, then):
+ """Inserts object into timer.
+
+ Args:
+ now (int): Current time in msec
+ obj (object): Object to be inserted
+ then (int): When to return the object strictly after.
+ """
+ then_key = int(then / self.bucket_size) + 1
+ for entry in self.entries:
+ # Add to first bucket we find. This should gracefully handle inserts
+ # for times in the past.
+ if entry.end_key >= then_key:
+ entry.queue.append(obj)
+ return
+
+ next_key = int(now / self.bucket_size) + 1
+ if self.entries:
+ last_key = self.entries[-1].end_key
+ else:
+ last_key = next_key
+
+ # Handle the case when `then` is in the past and `entries` is empty.
+ then_key = max(last_key, then_key)
+
+ # Add empty entries between the end of the current list and when we want
+ # to insert. This ensures there are no gaps.
+ self.entries.extend(
+ _Entry(key) for key in xrange(last_key, then_key + 1)
+ )
+
+ self.entries[-1].queue.append(obj)
+
+ def fetch(self, now):
+ """Fetch any objects that have timed out
+
+ Args:
+ now (ms): Current time in msec
+
+ Returns:
+ list: List of objects that have timed out
+ """
+ now_key = int(now / self.bucket_size)
+
+ ret = []
+ while self.entries and self.entries[0].end_key <= now_key:
+ ret.extend(self.entries.pop(0).queue)
+
+ return ret
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