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1bccf4f2dd
## 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.
63 lines
1.9 KiB
Go
63 lines
1.9 KiB
Go
// Copyright 2025 the libevm authors.
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//
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// The libevm additions to go-ethereum are free software: you can redistribute
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// them and/or modify them under the terms of the GNU Lesser General Public License
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// as published by the Free Software Foundation, either version 3 of the License,
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// or (at your option) any later version.
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//
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// The libevm additions are distributed in the hope that they will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
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// General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see
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// <http://www.gnu.org/licenses/>.
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package libevm
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import (
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"errors"
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"sync"
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"sync/atomic"
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)
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var (
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extrasMu sync.Mutex
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extrasHandle atomic.Uint64
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)
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// An ExtrasLock is a handle that proves a current call to
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// [WithTemporaryExtrasLock].
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type ExtrasLock struct {
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handle *uint64
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}
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// WithTemporaryExtrasLock takes a global lock and calls `fn` with a handle that
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// can be used to prove that the lock is held. All package-specific temporary
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// overrides require this proof.
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//
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// WithTemporaryExtrasLock MUST NOT be used on a live chain. It is solely
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// intended for off-chain consumers that require access to extras.
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func WithTemporaryExtrasLock(fn func(lock ExtrasLock) error) error {
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extrasMu.Lock()
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defer func() {
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extrasHandle.Add(1)
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extrasMu.Unlock()
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}()
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v := extrasHandle.Load()
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return fn(ExtrasLock{&v})
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}
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// ErrExpiredExtrasLock is returned by [ExtrasLock.Verify] if the lock has been
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// persisted beyond the call to [WithTemporaryExtrasLock] that created it.
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var ErrExpiredExtrasLock = errors.New("libevm.ExtrasLock expired")
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// Verify verifies that the lock is valid.
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func (l ExtrasLock) Verify() error {
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if *l.handle != extrasHandle.Load() {
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return ErrExpiredExtrasLock
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}
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return nil
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}
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