github.com/MetalBlockchain/subnet-evm@v0.4.9/core/gaspool.go (about)

     1  // (c) 2019-2020, Ava Labs, Inc.
     2  //
     3  // This file is a derived work, based on the go-ethereum library whose original
     4  // notices appear below.
     5  //
     6  // It is distributed under a license compatible with the licensing terms of the
     7  // original code from which it is derived.
     8  //
     9  // Much love to the original authors for their work.
    10  // **********
    11  // Copyright 2015 The go-ethereum Authors
    12  // This file is part of the go-ethereum library.
    13  //
    14  // The go-ethereum library is free software: you can redistribute it and/or modify
    15  // it under the terms of the GNU Lesser General Public License as published by
    16  // the Free Software Foundation, either version 3 of the License, or
    17  // (at your option) any later version.
    18  //
    19  // The go-ethereum library is distributed in the hope that it will be useful,
    20  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    21  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    22  // GNU Lesser General Public License for more details.
    23  //
    24  // You should have received a copy of the GNU Lesser General Public License
    25  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    26  
    27  package core
    28  
    29  import (
    30  	"fmt"
    31  	"math"
    32  )
    33  
    34  // GasPool tracks the amount of gas available during execution of the transactions
    35  // in a block. The zero value is a pool with zero gas available.
    36  type GasPool uint64
    37  
    38  // AddGas makes gas available for execution.
    39  func (gp *GasPool) AddGas(amount uint64) *GasPool {
    40  	if uint64(*gp) > math.MaxUint64-amount {
    41  		panic("gas pool pushed above uint64")
    42  	}
    43  	*(*uint64)(gp) += amount
    44  	return gp
    45  }
    46  
    47  // SubGas deducts the given amount from the pool if enough gas is
    48  // available and returns an error otherwise.
    49  func (gp *GasPool) SubGas(amount uint64) error {
    50  	if uint64(*gp) < amount {
    51  		return ErrGasLimitReached
    52  	}
    53  	*(*uint64)(gp) -= amount
    54  	return nil
    55  }
    56  
    57  // Gas returns the amount of gas remaining in the pool.
    58  func (gp *GasPool) Gas() uint64 {
    59  	return uint64(*gp)
    60  }
    61  
    62  func (gp *GasPool) String() string {
    63  	return fmt.Sprintf("%d", *gp)
    64  }