最近研究以太坊的时候同事讨论了一个问题,智能合约的构造函数是如何保证只执行一次的,记录一下。
智能合约在第一次执行的时候调用的是EVM的create函数,看代码
// Create creates a new contract using code as deployment code.
func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, value *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
// initialise a new contract and set the code that is to be used by the
// EVM. The contract is a scoped environment for this execution context
// only.
contract := NewContract(caller, AccountRef(contractAddr), value, gas)
contract.SetCallCode(&contractAddr, crypto.Keccak256Hash(code), code)
// 执行合约后返回值赋给ret
ret, err = run(evm, contract, nil)
// check whether the max code size has been exceeded
maxCodeSizeExceeded := evm.ChainConfig().IsEIP158(evm.BlockNumber) && len(ret) > params.MaxCodeSize
// if the contract creation ran successfully and no errors were returned
// calcu