client/common_lib/logging.py

"""\
Logging helper tools.
"""

__author__ = 'jadmanski@google.com (John Admanski)'


def record(fn):
	"""
	Generic method decorator for logging calls under the
	assumption that return=GOOD, exception=FAIL. The method
	determines parameters as:
		subdir = self.subdir if it exists, or None
		operation = "class name"."method name"
		status = None on GOOD, str(exception) on FAIL
	The object using this method must have a job attribute
	for the logging to actually occur, otherwise the logging
	will silently fail.

	Logging can explicitly be disabled for a call by passing
	a logged=False parameter
	"""
	def recorded_func(self, *args, **dargs):
		logged = dargs.pop('logged', True)
		job = getattr(self, 'job', None)
		# if logging is disabled/unavailable, just
		# call the method
		if not logged or job is None:
			return fn(self, *args, **dargs)
		# logging is available, so wrap the method call
		# in success/failure logging
		subdir = getattr(self, 'subdir', None)
		operation = '%s.%s' % (self.__class__.__name__,
				       fn.__name__)
		try:
			result = fn(self, *args, **dargs)
			job.record('GOOD', subdir, operation)
		except Exception, detail:
			job.record('FAIL', subdir, operation, str(detail))
			raise
		return result
	return recorded_func