Secp operations during txid computation

ElementsProject / rust-elements

Rust support for Elements transaction/block deserialization

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Secp operations during txid computation #202

Closed RCasatta closed 2 months ago

RCasatta commented 6 months ago

In a performance profile in a downstream project I noticed txid() is taking too much time even considering it's an expensive computation, in the flame graph there were calls to secp function which I don't think should happen?

Can share the performance graph if can help understand

apoelstra commented 6 months ago

Sure. What secp function was it?

RCasatta commented 6 months ago

I had to leave the PC... I remember fe_sqrt and others, will post tomorrow

RCasatta commented 6 months ago

Here are a convenient screenshot and the profiler json (to be loaded from chrome dev tools, performance tab)

For what I understand is how the PedersenCommitment is serialized with secp256k1_pedersen_commitment_serialize

Trace-20240510T085107.json

apoelstra commented 6 months ago

Ok, yeah, the issue is in libsecp256k1-zkp, not here. For some bizarre reason secp256k1_pedersen_commitment_serialize decompresses the point then recompresses it, when all it needs to do is a memcmp (I think). So this function is wasting a lot of time for no reason.

RCasatta commented 5 months ago

Issue has been fixed in the upstream lib, I think we need

secp256k1-zkp-sys upgrade to catch the changes
rust-secp256k1-zkp release
upgrade dep here (if rust-secp256k1-zkp not released as patch version)

apoelstra commented 4 months ago

Bumping secp-zkp requires bumping secp, which requires bumping bitcoin, which requires bumping bitcoind, which requires bumping elementsd.

I am almost done this. Opened https://github.com/RCasatta/elementsd/pull/18

apoelstra commented 4 months ago

The next version of rust-bitcoin will break out the "types that never change" into a new primitives crate which should be sufficient for most of the other crates in the ecosystem, and which should rarely have major version bumps, which will make this all way less painful.

RCasatta commented 2 months ago

Fixed with https://github.com/ElementsProject/rust-elements/pull/209 next release will take this