1// Copyright 2015 The go-ethereum Authors 2// This file is part of the go-ethereum library. 3// 4// The go-ethereum library is free software: you can redistribute it and/or modify 5// it under the terms of the GNU Lesser General Public License as published by 6// the Free Software Foundation, either version 3 of the License, or 7// (at your option) any later version. 8// 9// The go-ethereum library is distributed in the hope that it will be useful, 10// but WITHOUT ANY WARRANTY; without even the implied warranty of 11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12// GNU Lesser General Public License for more details. 13// 14// You should have received a copy of the GNU Lesser General Public License 15// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17package core 18 19import ( 20 "fmt" 21 "math" 22) 23 24// GasPool tracks the amount of gas available during execution of the transactions 25// in a block. The zero value is a pool with zero gas available. 26type GasPool uint64 27 28// AddGas makes gas available for execution. 29func (gp *GasPool) AddGas(amount uint64) *GasPool { 30 if uint64(*gp) > math.MaxUint64-amount { 31 panic("gas pool pushed above uint64") 32 } 33 *(*uint64)(gp) += amount 34 return gp 35} 36 37// SubGas deducts the given amount from the pool if enough gas is 38// available and returns an error otherwise. 39func (gp *GasPool) SubGas(amount uint64) error { 40 if uint64(*gp) < amount { 41 return ErrGasLimitReached 42 } 43 *(*uint64)(gp) -= amount 44 return nil 45} 46 47// Gas returns the amount of gas remaining in the pool. 48func (gp *GasPool) Gas() uint64 { 49 return uint64(*gp) 50} 51 52func (gp *GasPool) String() string { 53 return fmt.Sprintf("%d", *gp) 54} 55