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107 lines
3.2 KiB
Go
107 lines
3.2 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it 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
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// GNU Lesser 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 <http://www.gnu.org/licenses/>.
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package core
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import (
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"fmt"
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"math"
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)
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// GasPool tracks the amount of gas available for transaction execution
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// within a block, along with the cumulative gas consumed.
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type GasPool struct {
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remaining uint64
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initial uint64
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cumulativeUsed uint64
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}
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// NewGasPool initializes the gasPool with the given amount.
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func NewGasPool(amount uint64) *GasPool {
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return &GasPool{
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remaining: amount,
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initial: amount,
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}
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}
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// SubGas deducts the given amount from the pool if enough gas is
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// available and returns an error otherwise.
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func (gp *GasPool) SubGas(amount uint64) error {
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if gp.remaining < amount {
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return ErrGasLimitReached
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}
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gp.remaining -= amount
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return nil
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}
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// ReturnGas adds the refunded gas back to the pool and updates
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// the cumulative gas usage accordingly.
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func (gp *GasPool) ReturnGas(returned uint64, gasUsed uint64) error {
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if gp.remaining > math.MaxUint64-returned {
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return fmt.Errorf("%w: remaining: %d, returned: %d", ErrGasLimitOverflow, gp.remaining, returned)
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}
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// The returned gas calculation differs across forks.
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//
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// - Pre-Amsterdam:
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// returned = purchased - remaining (refund included)
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//
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// - Post-Amsterdam:
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// returned = purchased - gasUsed (refund excluded)
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gp.remaining += returned
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// gasUsed = max(txGasUsed - gasRefund, calldataFloorGasCost)
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// regardless of Amsterdam is activated or not.
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gp.cumulativeUsed += gasUsed
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return nil
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}
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// Gas returns the amount of gas remaining in the pool.
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func (gp *GasPool) Gas() uint64 {
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return gp.remaining
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}
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// CumulativeUsed returns the amount of cumulative consumed gas (refunded included).
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func (gp *GasPool) CumulativeUsed() uint64 {
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return gp.cumulativeUsed
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}
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// Used returns the amount of consumed gas.
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func (gp *GasPool) Used() uint64 {
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if gp.initial < gp.remaining {
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panic("gas used underflow")
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}
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return gp.initial - gp.remaining
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}
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// Snapshot returns the deep-copied object as the snapshot.
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func (gp *GasPool) Snapshot() *GasPool {
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return &GasPool{
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initial: gp.initial,
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remaining: gp.remaining,
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cumulativeUsed: gp.cumulativeUsed,
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}
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}
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// Set sets the content of gasPool with the provided one.
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func (gp *GasPool) Set(other *GasPool) {
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gp.initial = other.initial
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gp.remaining = other.remaining
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gp.cumulativeUsed = other.cumulativeUsed
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}
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func (gp *GasPool) String() string {
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return fmt.Sprintf("initial: %d, remaining: %d, cumulative used: %d", gp.initial, gp.remaining, gp.cumulativeUsed)
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}
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