Add default genesis to trait
#3164
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Depends on EspressoSystems/HotShot#3164
Avoids downstream implementations.
| where | ||
| <Self as BlockPayload>::Instance: Default, | ||
| { | ||
| Self::from_transactions([], &Default::default()).unwrap() |
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I think a default implementation makes sense, though I'm a little uncomfortable with a default implementation that may panic depending on how a non-default (from_transactions) is implemented.
It's not a huge deal since I guess this is just a startup panic, but is there any way to avoid this? e.g. are any of our from_transactions actually fallible?
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On quick review it appears that the implementation on the sequencer is used everywhere. The only real failure case I see is from_namespace_offsets. I'm assuming that it isn't a huge deal b/c it is itself being unwrapped. But maybe @ggutoski, @jbearer would have more insight.
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My opinion: it's okay because it's just a startup panic, so if there's something wrong then we'll know immediately and there's zero risk of loss. If from_transactions fails on an empty list then that's pretty bad and should be fixed. 😆
Regarding the current implementation details: please keep in mind that everything in sequencer/src/block is currently being rewritten, so don't worry to much about what's currently in there.
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Approving because this change seems pretty innocuous to me. See my reply below.
Regarding this explainer comment:
https://github.com/EspressoSystems/espresso-sequencer/blob/77484507b7b8a5e94ecbc38dcae356e90d9bbba6/sequencer/src/block.rs#L67-L70
Has this "future update to hotshot" occurred yet? Seems like it's still a "workaround" and we're merely doing the workaround at the trait level instead of in the underlying implementation. Correct? I see no problem with that. (Indeed, it makes sense to me to take care of it at the trait level.) I just want to clarify status.
| where | ||
| <Self as BlockPayload>::Instance: Default, | ||
| { | ||
| Self::from_transactions([], &Default::default()).unwrap() |
There was a problem hiding this comment.
My opinion: it's okay because it's just a startup panic, so if there's something wrong then we'll know immediately and there's zero risk of loss. If from_transactions fails on an empty list then that's pretty bad and should be fixed. 😆
Regarding the current implementation details: please keep in mind that everything in sequencer/src/block is currently being rewritten, so don't worry to much about what's currently in there.
Sorry I missed this comment. True, some discussion occurred with @jbearer where it was clarified that the appropriate action was to define this default function on the trait. I guess you could say that the work around is just being moved, but I'm not seeing a better solution. With this in HotShot we will be able to remove that comment and TODO on the sequencer side. |
Avoids downstream implementations.
We have a TODO in sequencer here:
https://github.com/EspressoSystems/espresso-sequencer/blob/77484507b7b8a5e94ecbc38dcae356e90d9bbba6/sequencer/src/block.rs#L65
This PR:
Adds a default implantation of
genesistoBlockPayload.This PR does not:
It should not change any functionality and only make changes that are required to complete the above.
Key places to review:
The intended change is in
BlockPayloadtrait incrates/types/src/traits/block_contents.rs. That defaultimplementation allows us to remove the implementation from
crates/example-types/src/block_types.rs.