tokensOfOwner function will eventually gas out about etherbots-bug-bounty HOT 8 OPEN

This was intentional to minimise storage costs. We'll look further into it but it's definitely not a bug ATM. Thanks!

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Noted. I guess just be aware that at some point it will become a bug in that it just won't return, one of CK's guys mentioned that their similar implementation stopped working completely on Geth after 100k tokens.

For example, our implementation of tokensOfOwner() has been entirely non-functional on geth (and I assume other full nodes) ever since we crossed 100k NFTs or so.

From ethereum/EIPs#721

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@ricky-dunn Ah that is very interesting (and if we change we will indeed award this bounty!) Thank you.

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@ricky-dunn Just looking at this -- is it a problem if it is never called by a contract? We only intend to use it for reading state.

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@ricky-dunn @RobbieFerguson it's explicitly listed as not to be called by a contract in any other code I have see, as it is gas hungry. It's a web3 utility function, NOT a contract to contract call. I don't see a use contract -> contract for it.

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@DanielMReed Yep, we have the same understanding and would never use it an inter-contract call.
My question is, will the web3 view function fail given a big enough data set to loop over? (For reasons unrelated to gas). Still confused about this. Thanks!

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@RobbieFerguson - even off-chain this will eventually prove problematic once a certain number of tokens is reached given it's a straight up loop over the entire supply.

In CryptoKitties case it looks like after reaching 100k tokens it no longer became functional off-chain via a full node, although not sure if they had tried to access this using a dedicated node or an Infura shared node, I suspect that may vary your mileage.

I appreciate as it's not used on-chain there's probably not a huge amount of focus, but if you did want to make if functional but not incur the overhead of storing part indexes on a per user basis (which would be a fair challenge given storage costs) you could consider including a function where you can pass in a startIndex and limit so off-chain callers can at least paginate their result sets, although this may be susceptible to race conditions so there is a trade-off there, but that's quite often the case with most things on the blockchain.

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@ricky-dunn We've made changes to the code based on this issue and so will discuss an appropriate bounty! Thanks.

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