def fetch_with_dist_lock(mc_store, mutex_key, fetcher, updater,
 lock_time=3*60*1000, sleep_time=100, retry_times=3):
 i = 0
 while i < retry_times:
 i += 1
 need_update, results = fetcher()
 if need_update:
 if(mc_store.add(mutex_key, lock_time)):
 try:
 updater()
 continue
 finally:
 #release the distribute mutex anyway
 mc_store.delete(mutex_key)
 else:
 time.sleep((sleep_time*1.0)/1000)
 continue
 return results
 #too much tries, but failed still.
 return None
def f_wrapper(f, *args, **kwargs):
 def _():
 return f(*args, **kwargs)
 return _
def update_with_dist_lock(mc_store, mutex_key, updater, lock_time=60*1000, sleep_time=100, retry_times=5):
 i = 0
 while i < retry_times:
 i += 1
 if (mc_store.add(mutex_key, lock_time)):
 try:
 updater()
 return True
 finally:
 mc_store.delete(mutex_key)
 else:
 time.sleep((sleep_time*1.0)/1000)
 continue
 return False