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#!/usr/bin/env python
# Copyright (C) 2012 OpenStack, LLC.
#
# 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.
# Manage jobs in Jenkins server
import errno
import io
import logging
import os
import re
import tempfile
import fasteners
import yaml
from jenkins_jobs import errors
logger = logging.getLogger(__name__)
class JobCache(object):
# ensure each instance of the class has a reference to the required
# modules so that they are available to be used when the destructor
# is being called since python will not guarantee that it won't have
# removed global module references during teardown.
_logger = logger
_os = os
_tempfile = tempfile
_yaml = yaml
def __init__(self, jenkins_url, flush=False):
cache_dir = self.get_cache_dir()
# One cache per remote Jenkins URL:
host_vary = re.sub(r"[^A-Za-z0-9\-\~]", "_", jenkins_url)
self.cachefilename = os.path.join(
cache_dir, "cache-host-jobs-" + host_vary + ".yml"
)
# generate named lockfile if none exists, and lock it
self._locked = self._lock()
if not self._locked:
raise errors.JenkinsJobsException(
"Unable to lock cache for '%s'" % jenkins_url
)
if flush or not os.path.isfile(self.cachefilename):
self.data = {}
else:
with io.open(self.cachefilename, "r", encoding="utf-8") as yfile:
self.data = yaml.safe_load(yfile)
logger.debug("Using cache: '{0}'".format(self.cachefilename))
def _lock(self):
self._fastener = fasteners.InterProcessLock("%s.lock" % self.cachefilename)
return self._fastener.acquire(delay=1, max_delay=2, timeout=60)
def _unlock(self):
if getattr(self, "_locked", False):
if getattr(self, "_fastener", None) is not None:
self._fastener.release()
self._locked = None
@staticmethod
def get_cache_dir():
home = os.path.expanduser("~")
if home == "~":
raise OSError("Could not locate home folder")
xdg_cache_home = os.environ.get("XDG_CACHE_HOME") or os.path.join(
home, ".cache"
)
path = os.path.join(xdg_cache_home, "jenkins_jobs")
if not os.path.isdir(path):
try:
os.makedirs(path)
except OSError as ose:
# it could happen that two jjb instances are running at the
# same time and that the other instance created the directory
# after we made the check, in which case there is no error
if ose.errno != errno.EEXIST:
raise
return path
def set(self, job, md5):
self.data[job] = md5
def clear(self):
self.data.clear()
def is_cached(self, job):
if job in self.data:
return True
return False
def has_changed(self, job, md5):
if job in self.data and self.data[job] == md5:
return False
return True
def save(self):
# use self references to required modules in case called via __del__
# write to tempfile under same directory and then replace to avoid
# issues around corruption such the process be killed
tfile = self._tempfile.NamedTemporaryFile(
dir=self.get_cache_dir(), delete=False
)
tfile.write(self._yaml.dump(self.data).encode("utf-8"))
# force contents to be synced on disk before overwriting cachefile
tfile.flush()
self._os.fsync(tfile.fileno())
tfile.close()
try:
self._os.rename(tfile.name, self.cachefilename)
except OSError:
# On Windows, if dst already exists, OSError will be raised even if
# it is a file. Remove the file first in that case and try again.
self._os.remove(self.cachefilename)
self._os.rename(tfile.name, self.cachefilename)
self._logger.debug("Cache written out to '%s'" % self.cachefilename)
def __del__(self):
# check we initialized sufficiently in case called
# due to an exception occurring in the __init__
if getattr(self, "data", None) is not None:
try:
self.save()
except Exception as e:
self._logger.error(
"Failed to write to cache file '%s' on "
"exit: %s" % (self.cachefilename, e)
)
self._unlock()
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