Remove horribly hacky getRandomKey implementation #41
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* Relies on implementation of all Map objects to be HashMap * Relies on implementation details of HashMap which changed for Java 8, so the code no longer works * Very poor randomness - because it selects a bucket first, colliding hashcodes will cause elements to be selected with dramatically reduced frequency
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Will check it out. Original was copied from Redis as one thing that it documents is that the algorithm is O(1). http://redis.io/commands/randomkey |
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@spullara any chance this could get looked at sometime soon? It means the library is broken on JDK8 or later. |
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I'm pretty sure I need to stick with the way Redis works. It is unacceptable to replace an O(1) algorithm with an O(n) algorithm... Not sure what to do yet for Java 8, probably have to find another HashMap implementation. |
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It's somewhat unfortunate that the way it achieves O(1) is by making the algorithm incorrect... (as the distribution is not actually random in the presence of hash collisions) |
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Oh I agree that is totally not random and unfortunate. My guess is that since people often have millions of keys in Redis that the alternative was untenable. |
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Given that as of this month Java 7 will no longer be getting updates, this is becoming increasingly problematic. Having such useful code be unavailable to users of current JDKs is less than ideal for many and downright awful for some. How about let's figure out how we can fix this? |
3 participants
Biggest downside is selecting a random element is now
O(N). Most unfortunate, but a slower working solution is better than a broken fast one...