Feature/javascript tracers

[LukaszRozmej]

Changes

• Adds Javascript tracing to Nethermind

TODO:

• Integrate ClearScrypt to run JavaScript code
• Invoke result method
• Invoke step method
  • Handle step optionality
• Invoke fault method
• Invoke enter and exit methods
  • Implement frame parameter
  • Implement result parameter
• Invoke setup method
  • Make sure the parameter is correctly passed
• Return results correctly
• Implement db parameter
• Implement log parameter
• Implement stack parameter in optimized way
• Implement memory parameter
  • Can we do it without copying?
• implement contract parameter
• Implement ctx parameter
  • pass blockhash
  • pass error ?
• Load bigInt
• Implement toWord function
• Implement toHex function
• Implement toAddress function
• Implement isPrecompiled function
• Implement slice function
• Implement toContract function
• Implement toContract2 function
• Change arrays to be marshaled to Uint8Array on JS side
• Potentially - Change how we handle V8 objects - maybe use V8Runtime to not parse all the JS every time from scratch
• Potentially - optimize the standard trace gathered as it is not needed, maybe change type hierarchies?
• Properly unit test everything :)
• Add postStep function to tracer
  • Due to different architecture we are not pre-calculating gasCost and refund before we execute the op-code. To not re-architecture the whole EVM for now we are adding postStep function to tracer where those values are available.
• Fix fault handling - based on GO code
  • Geth has this weird fault handling:

static OutOfGas -> step with error!

if (dynamicGas)
{
 if memory overflow (dynamic OutOfGas) -> step with error!
 else step
}
else step

do operation
if (error) fault

We currently will not reproduce it, but go with simple:

step
if (error) fault

That means that our step will never have error set to true but we will invoke fault if it errors. Lets try that for now and see how it works, in my opinion it shouldn't produce issues as users have to use defensive programming in step due to weird geth behavior.

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change - potentially breaks existing tracers in plugins
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

Notes on testing

• Create a JS tracer that uses all the exposed features.
• Create a script that will run this tracer on Geth and Nethermind node on last X (might not work past 64-128 blocks due to state pruning) blocks on every transaction. And later will compare the results.

https://github.com/Marchhill/jsTracerTest/tree/main

Documentation

Requires documentation update

• Yes
• No

If yes, link the PR to the docs update or the issue with the details labeled docs. Remove if not applicable.

Requires explanation in Release Notes

• Yes
• No

If yes, fill in the details here. Remove if not applicable.

Remarks

This PR will possibly replace #6093
Link to API: https://geth.ethereum.org/docs/developers/evm-tracing/custom-tracer

[Marchhill]

Good stuff.

The most important questions:

• Did we test old-style geth style tracers? (@Marchhill )
• Can we avoid adding fields to storage-cells?

I've only tested javascript tracers, I will run my script on some old tracers to test them out

[eliashezron]

seems good to me