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# 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.
from typing import Generic, List, TypeVar
T = TypeVar("T")
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] = []
class WheelTimer(Generic[T]):
"""Stores arbitrary objects that will be returned after their timers have
expired.
"""
def __init__(self, bucket_size: int = 5000) -> None:
"""
Args:
bucket_size: Size of buckets in ms. Corresponds roughly to the
accuracy of the timer.
"""
self.bucket_size: int = bucket_size
self.entries: List[_Entry[T]] = []
self.current_tick: int = 0
def insert(self, now: int, obj: T, then: int) -> None:
"""Inserts object into timer.
Args:
now: Current time in msec
obj: Object to be inserted
then: When to return the object strictly after.
"""
then_key = int(then / self.bucket_size) + 1
if self.entries:
min_key = self.entries[0].end_key
max_key = self.entries[-1].end_key
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)
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 range(last_key, then_key + 1))
self.entries[-1].queue.append(obj)
def fetch(self, now: int) -> List[T]:
"""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
def __len__(self) -> int:
return sum(len(entry.queue) for entry in self.entries)
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