class SynchronizedResourceAccessor:
def __init__(self, lockfile, lock_expiry):
self.lock = HdfsLock(lockfile, lock_expiry)
def lock_execute_unlock(self, obj, function_name, *function_args):
"""
Obtains a lock then executes given function and finally releases lock.
@param:
obj: object or module
function_name: name of the function to be executed. Must be a string.
function_args: arguments to the function
@return:
status: 0 on successful execution
1 on failure
-1 on partially successful execution. E.g. given function was executed successfully but error occurred during lock release
result: return value of given function executed on given object
errors: list of errors occurred during executing the method in order of their occurrence.
contains exceptions thrown during the execution
"""
status,result,errors = 1,'',''
errors = []
lockAquired = False
try:
lockAquired = self.lock.acquire()
if lockAquired:
result = getattr(obj, function_name)(*function_args)
status = 0
except Exception as e:
errors.append(e)
finally:
if lockAquired:
try:
self.lock.release()
except HdfsLockException as e:
status = -1 if status == 0 else status
errors.append(e)
if not lockAquired:
errors.append(Exception('could not acquire lock while executing ' + function_name))
return status,result,errors
def __init__(self, lockfile, lock_expiry):
self.lock = HdfsLock(lockfile, lock_expiry)
