Offline evaluator to use in NewmChainService

[sae3023]

There's a FIXME in NewmChainService about using something that would allow you to omit Ogmois.

Scalus contains an offline Plutus script evaluator, and this commit in my fork adds a tiny integration of the evaluator to newm-server.

Glad to ask any questions or to help with further integration.

[AndrewWestberg]

Remove helper function in favor of String.hexToByteArray() extension function in io.newm.chain.util.CardanoKtx

[AndrewWestberg]

Where do the plutus cost models come into play here? Are they hardcoded somewhere in CardanoInfo? If so, this seems brittle and we should get the plutus cost model from the blockchain instead.

[sae3023]

Indeed, the CostModels are in ProtocolParameters, which are in CardanoInfo.

The evaluator itself needs only the slot config, the major protocol version and the cost models, so if the following signature is fine:

fun evaluateTx(
        cborBytes: ByteArray,
        utxos: Set<Utxo>,
        slotConfig: SlotConfig,
        costModels: CostModels
    )

Both of these types seem to be very straightforward to map to Scalus ledger types

[sae3023]

if this looks fine, I'd appreciate a hint of where these types are described in newm, and I'll ping you when I fix the function

[AndrewWestberg]

@sae3023 In TransactionBuilder.kt, it is constructed with a protocolParametersResult. Inside this structure is the plutusCostModels. All of this data currently comes from Ogmios through Kogmios which is our Ogmios gRPC wrapper in Kotlin. We're not trying to entirely eliminate Ogmios with this fix, just utilize Scalus where it makes sense for efficiency.

[sae3023]

@AndrewWestberg PTAL

I did the cost models, but I'm not entirely sure about the casts, doesn't look like it's the best way to do it, but I've sort of threw it together quickly.

I'll take another look in the morning too.

[wlara]

Is RedeemerTag an enum and RedeemerTag.valueOf() returns the value? If so, we should use the enum values directly here in the left side. Example:

 RedeemerTag.Spend -> "spend"

[sae3023]

done, lmk if there's anything else I can do

[AndrewWestberg]

@sae3023 Please run ./gradlew ktlF and it should fix the code formatting and allow the ktlint check to pass.

Also run ./gradlew test locally to see the compiler errors.

[sae3023]

@AndrewWestberg please take another look

[sae3023]

Hello again! I can see that the tests are failing, however, I feel a little out of my depth trying to investigate and fix it. Is there any chance you can take a look at the remaining errors and the root cause?