feat(runner): Enable starting testnet follower from state-sync #105
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| Number(currentBlockInfo.result.block.header.height) - | ||
| stateSyncInterval, |
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Does this calculation work even if the height is much greater than the stateSyncInterval, and the interval is a fairly large number? I don't know the semantics of what you're trying to do here; it would be worth a comment.
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This is pretty standard state-sync, which requires a "root of trust". This is basically configuring state-sync saying we'll trust any block after the given height (and corresponding hash). The goal is to give something recent enough so that it doesn't need to verify too many blocks hashes with the light client, but old enough that there exists a state-sync snapshot taken after that block height.
Most state-sync instructions/scripts out there basically do this "latest block height - some offset" math without giving much explanation as to why. This is what I've gathered from understanding how state-sync works.
I'll add a comment adding an explanation.
Clarify what trustHeight is
This change adds an option in preparation of Agoric/agoric-sdk#3769 to allow the testnet runner to join using a state-sync snapshot instead of catching up from genesis. This will be exercised in the CI deployment integration test once https://github.com/Agoric/agoric-sdk/compare/mhofman/5542-export-state-sync gets merged.
I have locally verified that these changes together are sufficient for that test to use state-sync (using agoric-sdk's
run-deployment-integration.shscript)