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Some pylint cleanup
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Ben Cotton committed Dec 17, 2014
1 parent b5db59a commit 90c3703
Showing 1 changed file with 62 additions and 58 deletions.
120 changes: 62 additions & 58 deletions cache_config.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,13 +3,13 @@
###### COPYRIGHT NOTICE ########################################################
#
# Copyright (C) 2007-2011, Cycle Computing, 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.txt
#
#
# 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.
Expand All @@ -34,7 +34,7 @@
#
# The cache_config script will attempt to pull an updated configuration for a machine
# from the URL list, stopping when it successfully pulls config from a URL. It will
# store the config on disk, with a time-to-live, and use the cached copy of the
# store the config on disk, with a time-to-live, and use the cached copy of the
# config if the time-to-live has not expired. It will keep using the cached copy if
# no new copy can be successfully fetched from any source on the URL list.

Expand Down Expand Up @@ -65,21 +65,21 @@


# LOGGING CONFIGURATION
log_level_map = dict()
log_level_map['1'] = logging.DEBUG
log_level_map['2'] = logging.INFO
log_level_map['3'] = logging.WARNING
log_level_map['4'] = logging.ERROR
log_level_map['5'] = logging.CRITICAL
log_level_map = dict()
log_level_map['1'] = logging.DEBUG
log_level_map['2'] = logging.INFO
log_level_map['3'] = logging.WARNING
log_level_map['4'] = logging.ERROR
log_level_map['5'] = logging.CRITICAL

env_var = '_CACHE_TOOL_DEBUG'
should_log = os.environ.has_key(env_var) and log_level_map.has_key(os.environ[env_var])
env_var = '_CACHE_TOOL_DEBUG'
should_log = os.environ.has_key(env_var) and log_level_map.has_key(os.environ[env_var])

if should_log:
logLevel=log_level_map[os.environ[env_var]]
logLevel = log_level_map[os.environ[env_var]]
else:
logLevel=logging.CRITICAL
logLevel = logging.CRITICAL

logging.basicConfig(level=logLevel,
format='%(asctime)s %(levelname)-8s %(message)s',
datefmt='%a, %d %b %Y %H:%M:%S',
Expand All @@ -89,8 +89,8 @@
# Python http_proxy incompatibility for http_proxy:
# handle the case where it does not start with http://
for http_proxy in ['http_proxy', 'HTTP_PROXY']:
if os.environ.has_key(http_proxy) and os.environ[http_proxy][:7] !="http://":
os.environ[http_proxy]="http://"+os.environ[http_proxy]
if os.environ.has_key(http_proxy) and os.environ[http_proxy][:7] != "http://":
os.environ[http_proxy] = "http://"+os.environ[http_proxy]
break

# SEED CONFIGURATION
Expand Down Expand Up @@ -118,25 +118,26 @@ def __init__(self, directory_name, step_base=1, step_random_coeff=0.2):
self.isStepRandom = step_random_coeff == 0.0
self.timeStep = step_base*(1+(step_random_coeff*(1.0-2*random.random())))
logging.info('Created a directory lock with timeStep %s seconds.' % str(self.timeStep))


def acquire(self, acquire_by_force=True, lock_timeout=30):
'''Attempt to acquire the lock, with a configuration timeout value. Return True if
acquired. False if acquie was forced. Raises DirectoryLockError if directory is
already locked.'''
if lock_timeout <= 0:
logmsg = "Error Acquiring DirectoryLock: '%s' with invalid timeout of '%d' seconds" % (self.dirName, lock_timeout)
logmsg = "Error Acquiring DirectoryLock: '%s' with invalid timeout of '%d' seconds" % \
(self.dirName, lock_timeout)
logging.error(logmsg)
raise DirectoryLockError(logmsg)

if self.isLocked == True:
logmsg="Error Acquiring DirectoryLock: '%s' is already locked!" % self.dirName
logmsg = "Error Acquiring DirectoryLock: '%s' is already locked!" % self.dirName
logging.error(logmsg)
raise DirectoryLockError(logmsg)
wait_duration=0

wait_duration = 0
logging.info("Acquiring lock")

while wait_duration < lock_timeout:
wait_duration += self.timeStep
try:
Expand All @@ -162,30 +163,30 @@ def acquire(self, acquire_by_force=True, lock_timeout=30):
logmsg = "Error acquiring DirectoryLock on '%s'" % self.dirName
logging.error(logmsg)
raise DirectoryLockError(logmsg)


def __del__(self):
'''Automatically destroy the lock when the object is deleted.'''
if self.isLocked:
self.release(True)


def release(self, raise_remove_error=False):
'''Release the lock. Raises DirectoryLockError if lock cannot be removed
or does not exist.'''
if not self.isLocked:
logmsg = "Error releasing DirectoryLock: '%s' is not locked yet!" % self.dirName
logging.error(logmsg)
raise DirectoryLockError(logmsg)
self.isLocked=False
self.isLocked = False
try:
os.rmdir(self.dirName)
except os.error, err:
if raise_remove_error:
logmsg="Error releasing DirectoryLock: '%s' remove appeared to fail!" % self.dirName
logmsg = "Error releasing DirectoryLock: '%s' remove appeared to fail!" % self.dirName
logging.error(logmsg)
raise DirectoryLockError(logmsg)


class CacheConfigFile:
'''An object representation of a config cache file. Provides some utility
Expand All @@ -197,45 +198,44 @@ def __init__(self, filename, ttl=30):
randStr = '.'+hex(int(random.random()*256*256*256*256))[2:10]
self.tempFileName = filename+randStr
logging.info("CacheConfigFile created with tempFileName: %s"%self.tempFileName)

def __del__(self):
'''Clean up any temporary files that were created.'''
if os.path.isfile(self.tempFileName):
os.remove(self.tempFileName)

def temporaryFileName(self):
'''Return the name of a unique, temporary file we can use.'''
return self.tempFileName

def exists(self):
'''Returns True if the cache file exists on disk, otherwise False.'''
return os.path.exists(self.fileName)



def shouldUpdate(self):
'''Check the cache file\'s timestamp against the TTL value for this file
set when the object was created. Return True if the TTL has expired.
Otherwise False.'''
currentTime=time.time()
currentTime = time.time()
if self.exists():
lastModified=os.path.getmtime(self.fileName)
lastModified = os.path.getmtime(self.fileName)

logging.info("CacheConfigFile last modified: %s" % lastModified)
cacheAge=currentTime-lastModified
cacheAge = currentTime-lastModified
logging.info("CacheConfigFile age: %s" % cacheAge)
if cacheAge < float(self.fileTTL):
logging.info("CacheConfigFile can be reused!")
return False
logging.info("CacheConfigFile should be updated!")
return True


class CustomHttpHandler(urllib2.HTTPHandler):
'''Handler helper class for dealing with URL requests.'''

def http_error_304(self, req, fp, code, msg, hdrs):
return open(self.cache_file)



################################################################################
Expand All @@ -250,7 +250,7 @@ def writeToFile(in_fp, out_fp, error):
stream named CONFIG_FILE_ERROR.'''
# Track errors encountered
config_lines = []

try:
if error:
config_lines.append(error)
Expand All @@ -265,14 +265,14 @@ def writeToFile(in_fp, out_fp, error):
skip_next = True
else:
config_lines.append(current_line)
current_line=in_fp.readline()
current_line = in_fp.readline()

config = ''.join(config_lines)
out_fp.write(config)
return config
finally:
in_fp.close()



def downloadConfig(url, cache_file, temp_cache_file_fp, lastAttempt):
Expand All @@ -285,7 +285,7 @@ def downloadConfig(url, cache_file, temp_cache_file_fp, lastAttempt):
opener = urllib2.build_opener(handler)
opener.addheaders = [('User-agent', 'CacheConfig/%s' % __version__)]
urllib2.install_opener(opener)

try:
req = urllib2.Request(url=url)
if os.path.exists(cache_file):
Expand Down Expand Up @@ -322,44 +322,48 @@ def main():
cache_lock_timeout = int(sys.argv[3])
cache_config_file = CacheConfigFile(cache_file_name, cache_file_timeout)
config_urls = sys.argv[4:]
logging.debug("CacheFile Name: %s\nCacheFile TTL: %d\nLock TTL: %d\n" % (cache_file_name, cache_file_timeout, cache_lock_timeout))
logging.debug("CacheFile Name: %s\nCacheFile TTL: %d\nLock TTL: %d\n" % \
(cache_file_name, cache_file_timeout, cache_lock_timeout))
for u in config_urls:
logging.debug("Config URL: %s" %u)
except:
logging.error("Error parsing arguments...")
return 1

try:
# Generate an app-specific directory name for our lock and then
# attempt to get a lock on it.
directoryName = cache_config_file.fileName + '_'
dlock = DirectoryLock(directoryName)
dlock.acquire(True, cache_lock_timeout)
except DirectoryLockError, error:
logging.error("Error acquiring directory lock!")
logging.error("Error acquiring directory lock: %s" % error)
pass

config = None
should_print = False
error_occurred = False
error_messages = []

# Once acquired, if cachefile doesn't exist or it is beyond its time to live (TTL),
# request the configuration file from the URL given. One the configuration has been
# fetched withou error, write it to temporary file and then move it in to place .
should_update = cache_config_file.shouldUpdate()
if should_update:
url_counter = 0
# Keep moving through the URLs in the list until we can pull a configuration
while should_print == False and url_counter < len(config_urls):
while should_print == False and url_counter < len(config_urls):
try:
error_occurred = False
logging.info("Opening temp cache file: %s" % cache_config_file.temporaryFileName())
logging.info("Opening temp cache file: %s" % \
cache_config_file.temporaryFileName())
temp_cache_file_fp = open(cache_config_file.temporaryFileName(), 'w')
try:
logging.info("Opening URL #%d: %s" % (url_counter+1, config_urls[url_counter]))
logging.info("Opening URL #%d: %s" % \
(url_counter+1, config_urls[url_counter]))
lastAttempt = url_counter == len(config_urls) - 1
config = downloadConfig(config_urls[url_counter], cache_config_file.fileName, temp_cache_file_fp, lastAttempt)
config = downloadConfig(config_urls[url_counter], \
cache_config_file.fileName, temp_cache_file_fp, lastAttempt)
finally:
temp_cache_file_fp.close()
logging.info("Copying tempCacheConfig file to cacheFile")
Expand Down Expand Up @@ -395,11 +399,11 @@ def main():
should_print = True
except:
error_occurred = True

if should_log:
# If we are logging, give the user a chance to read the output.
time.sleep(5)

if should_print and not error_occurred:
print config
else:
Expand Down

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