## Why this should be merged
In lieu of modifications to `core.IntrinsicGas()`, required for support
of Warp in SAE.
If we were to introduce variadic `options.Option`s to `IntrinsicGas()`,
it's impossible to guarantee that they would always be passed. The
`types.Transaction` itself isn't actually passed to `IntrinsicGas()`
either, so we can't rely on it to carry payloads/hooks.
## How this works
`vm.Hooks` are extended to include `PreprocessingGasCharge(tx
common.Hash) (uint64, error)`, which returns the amount of gas to be
charged between `core.IntrinsicGas` and `vm.EVM` execution charges. The
two entry points to execution, `vm.EVM.Call()` and `vm.EVM.Create()` are
modified to first spend said charge before running upstream logic.
The new hook is defined on a separate interface definition, embedded in
`vm.Hooks`, to allow types to implement just that method and enforce it
with the `var _ vm.Preprocessor = (*impl)(nil)` pattern.
## How this was tested
Integration tests via both `core.ApplyTransaction()` and
`core.ApplyMessage()`. The former is more comprehensive, while the
latter allows for inspection of interim error values.
---------
Signed-off-by: Arran Schlosberg <519948+ARR4N@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Austin Larson <78000745+alarso16@users.noreply.github.com>
## Why this should be merged
The `temporary.WithTempRegisteredExtras()` global lock introduced in
#234 wasn't fit for purpose when used in `coreth` as it required central
coordination of registration, types, and usage of the payload accessor.
## How this works
Instead of a central registration point, the new
`libevm.WithTemporaryExtrasLock()` function takes out a global lock and
provides the caller with a handle that proves the lock is held. All of
the override functions, e.g. `params.WithTempRegisteredExtras()` now
require a current lock, which will be propagated by the respective
`coreth` functions.
See https://github.com/ava-labs/coreth/pull/1328 for intended usage in
`coreth` and `subnet-evm`. A consumer of both of these can then safely
do the following:
```go
import (
"github.com/ava-labs/libevm/libevm"
coreth "github.com/ava-labs/coreth/plugin/evm"
subnet "github.com/ava-labs/subnet-evm/plugin/evm"
)
// asCChain calls `fn` while emulating `coreth`. It is safe for concurrent usage with [asSubnetEVM].
func asCChain(fn func() error) error {
return libevm.WithTemporaryExtrasLock(func(l libevm.ExtrasLock) error {
return coreth.WithTempRegisteredLibEVMExtras(l, fn)
})
}
// asSubnetEVM calls `fn` while emulating `subnet-evm`. It is safe for concurrent usage with [asCChain].
func asSubnetEVM(fn func() error) error {
return libevm.WithTemporaryExtrasLock(func(l libevm.ExtrasLock) error {
return subnet.WithTempRegisteredLibEVMExtras(l, fn)
})
}
```
## How this was tested
Unit test of the new function plus existing integration tests of all
modified code.
## Why this should be merged
Registration of extras requires runtime enforcement of payload types. In
production, only a single set of types can be registered and any
attempts at re-registration will panic (by design). Although this makes
production usage safe, it doesn't allow downstream consumers (e.g. data
indexers) to use extras from different chains (e.g. `coreth` _and_
`subnet-evm`) at the same time.
## How this works
1. The `libevm/register.AtMostOnce` type can now be overridden
temporarily.
2. `params`, `core/types`, `core/vm`, and `state` packages introduce
`WithTempRegisteredExtras()` functions.
3. `libevm/temporary.WithRegisteredExtras()` provides "atomic" override
of all extras.
In all cases, the scope of the override is limited to the life of a
single function call.
## How this was tested
Relative to numbered list above:
1. Unit test of new and existing functionality.
2. Integration tests of both packages, demonstrating both payload and
behavioural override.
## Why this should be merged
Importing some `avalanchego` test fixtures automatically imports
`coreth` packages that register extras, which affects testing of other
VMs that depend on `libevm`. All other registered extras can be cleared
with the pattern in this PR.
## How this works
Uses the `register.AtMostOnce` type already used in `params` and
`types`. I forgot to update the `vm` package when implementing the type.
## How this was tested
Existing unit tests.
* feat: override `vm.NewEVM()` args
* test: `vm.Hooks.OverrideNewEVMArgs`
* refactor: use `NewEVMArgs struct` in hook
* chore: `gci`
* fix: clear `vm.Hooks` at end of test
