| # |
| # 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. |
| # |
| |
| """Sample disk usage under a particular path |
| |
| This module provides threads which can be used to gather information on the disk utilisation |
| under a particular path. |
| """ |
| |
| import threading |
| import time |
| |
| from twitter.common import log |
| from twitter.common.dirutil import du |
| from twitter.common.exceptions import ExceptionalThread |
| from twitter.common.lang import Lockable |
| |
| |
| class DiskCollectorThread(ExceptionalThread): |
| """ Thread to calculate aggregate disk usage under a given path using a simple algorithm """ |
| |
| def __init__(self, path): |
| self.path = path |
| self.value = None |
| self.event = threading.Event() |
| super(DiskCollectorThread, self).__init__() |
| self.daemon = True |
| |
| def run(self): |
| start = time.time() |
| self.value = du(self.path) |
| log.debug("DiskCollectorThread: finished collection of %s in %.1fms", |
| self.path, 1000.0 * (time.time() - start)) |
| self.event.set() |
| |
| def finished(self): |
| return self.event.is_set() |
| |
| |
| class DiskCollector(Lockable): |
| """ Spawn a background thread to sample disk usage """ |
| |
| def __init__(self, root): |
| self._root = root |
| self._thread = None |
| self._value = 0 |
| super(DiskCollector, self).__init__() |
| |
| @Lockable.sync |
| def sample(self): |
| """ Trigger collection of sample, if not already begun """ |
| if self._thread is None: |
| self._thread = DiskCollectorThread(self._root) |
| self._thread.start() |
| |
| @property |
| @Lockable.sync |
| def value(self): |
| """ Retrieve value of disk usage """ |
| if self._thread is not None and self._thread.finished(): |
| self._value = self._thread.value |
| self._thread = None |
| return self._value |
| |
| @property |
| @Lockable.sync |
| def completed_event(self): |
| """ Return a threading.Event that will block until an in-progress disk collection is complete, |
| or block indefinitely otherwise. Use with caution! (i.e.: set a timeout) """ |
| if self._thread is not None: |
| return self._thread.event |
| else: |
| return threading.Event() |
