RedisCache.clear may return integer instead of boolean

[spacewander]

I am using python 2.7.12 with :

redis==2.10.6
werkzeug==0.12.2

According to the documentation, werkzeug.contrib.cache.RedisCache.clear should return a boolean value to indicate Whether the cache has been cleared.
However, because self._client.delete(*keys) returns an integer as the number of keys removed, the actual returned value could be an integer. And since clear is not atomic, the returned number may be not equal to the len(keys).

Maybe we could set status according to existence of redis.exceptions.ResponseError?
For example:

status = True
try:
      self._client.delete(*keys)
except redis.exceptions.ResponseError:
      status = False

BTW, if there is nothing to clear, RedisCache.clear will return False. On the same occasion, FileSystemCache.clear will return True. The documentation about this occasion is not clear.

I could submit a patch if those behaviors are considered as bug.

[spacewander]

One more thing, RedisCache.clear should not use keys to get all keys.

Use keys in production is not recommended. Some people even suggest to rename keys command in production environment. I observed the mistake in a PHP background task before. The keys operation locked the Redis for more than 1 second, caused a great number of redis operation timeouts. I am not willing to see this happens again.

There is already an issue about replacing keys with scan(#1069), but there is not a related pull request yet.

[lepture]

close it via #1249