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# coding:utf-8
import functools
import logging
import sys
import traceback
import warnings
# Use module-specific logger with a default null handler.
_logger = logging.getLogger('backoff')
_logger.addHandler(logging.NullHandler()) # pragma: no cover
_logger.setLevel(logging.INFO)
# Evaluate arg that can be either a fixed value or a callable.
def _maybe_call(f, *args, **kwargs):
return f(*args, **kwargs) if callable(f) else f
def _init_wait_gen(wait_gen, wait_gen_kwargs):
kwargs = {k: _maybe_call(v) for k, v in wait_gen_kwargs.items()}
return wait_gen(**kwargs)
def _next_wait(wait, jitter, elapsed, max_time):
value = next(wait)
try:
if jitter is not None:
seconds = jitter(value)
else:
seconds = value
except TypeError:
warnings.warn(
"Nullary jitter function signature is deprecated. Use "
"unary signature accepting a wait value in seconds and "
"returning a jittered version of it.",
DeprecationWarning,
stacklevel=2,
)
seconds = value + jitter()
# don't sleep longer than remaining alloted max_time
if max_time is not None:
seconds = min(seconds, max_time - elapsed)
return seconds
# Configure handler list with user specified handler and optionally
# with a default handler bound to the specified logger.
def _config_handlers(user_handlers, default_handler=None, logger=None):
handlers = []
if logger is not None:
# bind the specified logger to the default log handler
log_handler = functools.partial(default_handler, logger=logger)
handlers.append(log_handler)
if user_handlers is None:
return handlers
# user specified handlers can either be an iterable of handlers
# or a single handler. either way append them to the list.
if hasattr(user_handlers, '__iter__'):
# add all handlers in the iterable
handlers += list(user_handlers)
else:
# append a single handler
handlers.append(user_handlers)
return handlers
# Default backoff handler
def _log_backoff(details, logger):
msg = "Backing off %s(...) for %.1fs (%s)"
log_args = [details['target'].__name__, details['wait']]
exc_typ, exc, _ = sys.exc_info()
if exc is not None:
exc_fmt = traceback.format_exception_only(exc_typ, exc)[-1]
log_args.append(exc_fmt.rstrip("\n"))
else:
log_args.append(details['value'])
logger.info(msg, *log_args)
# Default giveup handler
def _log_giveup(details, logger):
msg = "Giving up %s(...) after %d tries (%s)"
log_args = [details['target'].__name__, details['tries']]
exc_typ, exc, _ = sys.exc_info()
if exc is not None:
exc_fmt = traceback.format_exception_only(exc_typ, exc)[-1]
log_args.append(exc_fmt.rstrip("\n"))
else:
log_args.append(details['value'])
logger.error(msg, *log_args)
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