Utility functions for working with bloom filters

[0xOlias]

Bloom filters are a core Ethereum data structure, so it seems reasonable for viem to offer utility functions for working with them.

Use case

My particular use case is checking if a block contains logs matching a log filter (addresses and topics) using the block.logsBloom field. (I actually can't think of any other use cases, because AFAIK this is the only bloom filter that Ethereum exposes externally).

References

Web3.js has a few utility functions for bloom filters. They appear to be a re-export of the ethereum-bloom-filters package, which could be a good starting point.

API

We could start with just a single function to check if a value is present in a bloom filter. This function would validate that the bloom filter is a valid Ethereum logs bloom filter, and return a boolean.

export type IsInBloomFilterParameters = {
  value: Hex | ByteArray
  bloom: Hex | ByteArray
}

function isInBloomFilter(parameters: IsInBloomFilterParameters): boolean

We could also consider supporting a plural version that accepts multiple values, and returns early if any values match. This would be useful for the use case described above.

export type IsInBloomFilterParameters = {
  value: Hex | ByteArray | (Hex | ByteArray)[]
  bloom: Hex | ByteArray
}

// ...

[tmm]

Currently focused on other things, but down for a contribution!

[0xOlias]

Same 😅. Going to use ethereum-bloom-filters for now, but would love to contribute a viem implementation and run some benchmarks at some point. cc @OlaStenberg who did some work with bloom filters in js/ts recently.

[joshstevens19]

Would you be willing to accept a PR with ethereum bloom filter package installed? I am the creator of that package happen to do a PR here so others can use it?

[jxom]

Hey @joshstevens19! If we were to ever implement this, would you mind if we adapt your code (with references to your repo of course / add you as coauthor) into Viem? This way, we can still keep our dependency tree fairly slim, and not have to pull in js-sha3 (we use @noble/hashes).

[kyscott18]

I'm willing to contribute by adding some bloom filter utilities. I implemented some bloom filter utilities in Ponder (https://github.com/ponder-sh/ponder/blob/main/packages/core/src/sync-realtime/bloom.ts) using viem utilities based off of Alloy.

API

const isLogInBloomFilter: (params: { bloomFilter: Hex, log: Pick<Log, "address" | "topics"> }) => boolean;

Could also be nice to have zeroLogsBloom or accrueLogsBloom.

[jxom]

Bloom filters are being removed from the protocol: ethereum/EIPs#8368

Unsure if worth supporting.

[kyscott18]

I think it would still be useful for:

1. Historical blocks that still contain logsBloom

2. Chains that don't implement this EIP

but completely up to you