can we only have one check?

tags: learning programming

content

in the below code, can we remove the first check?

Transclude of double-checked-lock#typical-double-check

in other words, can we have:

with lock:
	if not cache_valid():  # second check
		return refresh_cache()
	return get_cache()
return get_cache()

from the perspective of user experience, this works
but from the POV of program, this is not optimal, because:
- now every single thread needs to acquire the lock before reading
- but in reality, only the thread that needs to refresh the cache will need the lock

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