Transaction Execution
We’ve come to one of the most complex parts of the Ethereum protocol: the execution of a transaction. Say you send a transaction off into the Ethereum network to be processed. What happens to transition the state of Ethereum to include your transaction?
Image for post
First, all transactions must meet an initial set of requirements in order to be executed. These include:
The transaction must be a properly formatted RLP. “RLP” stands for “Recursive Length Prefix” and is a data format used to encode nested arrays of binary data. RLP is the format Ethereum uses to serialize objects.
Valid transaction signature.
Valid transaction nonce. Recall that the nonce of an account is the count of transactions sent from that account. To be valid, a transaction nonce must be equal to the sender account’s nonce.
The transaction’s gas limit must be equal to or greater than the intrinsic gas used by the transaction. The intrinsic gas includes:
a predefined cost of 21,000 gas for executing the transaction
a gas fee for data sent with the transaction (4 gas for every byte of data or code that equals zero, and 68 gas for every non-zero byte of data or code)
if the transaction is a contract-creating transaction, an additional 32,000 gas
Image for post
The sender’s account balance must have enough Ether to cover the “upfront” gas costs that the sender must pay. The calculation for the upfront gas cost is simple: First, the transaction’s gas limit is multiplied by the transaction’s gas price to determine the maximum gas cost. Then, this maximum cost is added to the total value being transferred from the sender to the recipient.
Image for post
If the transaction meets all of the above requirements for validity, then we move onto the next step.
First, we deduct the upfront cost of execution from the sender’s balance, and increase the nonce of the sender’s account by 1 to account for the current transaction. At this point, we can calculate the gas remaining as the total gas limit for the transaction minus the intrinsic gas used.
Image for post
Next, the transaction starts executing. Throughout the execution of a transaction, Ethereum keeps track of the “substate.” This substate is a way to record information accrued during the transaction that will be needed immediately after the transaction completes. Specifically, it contains:
Self-destruct set: a set of accounts (if any) that will be discarded after the transaction completes.
Log series: archived and indexable checkpoints of the virtual machine’s code execution.
Refund balance: the amount to be refunded to the sender account after the transaction. Remember how we mentioned that storage in Ethereum costs money, and that a sender is refunded for clearing up storage? Ethereum keeps track of this using a refund counter. The refund counter starts at zero and increments every time the contract deletes something in storage.
Next, the various computations required by the transaction are processed.
Once all the steps required by the transaction have been processed, and assuming there is no invalid state, the state is finalized by determining the amount of unused gas to be refunded to the sender. In addition to the unused gas, the sender is also refunded some allowance from the “refund balance” that we described above.
Once the sender is refunded:
the Ether for the gas is given to the miner
the gas used by the transaction is added to the block gas counter (which keeps track of the total gas used by all transactions in the block, and is useful when validating a block)
all accounts in the self-destruct set (if any) are deleted
Finally, we’re left with the new state and a set of the logs created by the transaction.
Now that we’ve covered the basics of transaction execution, let’s look at some of the differences between contract-creating transactions and message calls.
Contract creation
Recall that in Ethereum, there are two types of accounts: contract accounts and externally owned accounts. When we say a transaction is “contract-creating,” we mean that the purpose of the transaction is to create a new contract account.
In order to create a new contract account, we first declare the address of the new account using a special formula. Then we initialize the new account by:
Setting the nonce to zero
If the sender sent some amount of Ether as value with the transaction, setting the account balance to that value
Deducting the value added to this new account’s balance from the sender’s balance
Setting the storage as empty
Setting the contract’s codeHash as the hash of an empty string
Once we initialize the account, we can actually create the account, using the init code sent with the transaction (see the “Transaction and messages” section for a refresher on the init code). What happens during the execution of this init code is varied. Depending on the constructor of the contract, it might update the account’s storage, create other contract accounts, make other message calls, etc.
As the code to initialize a contract is executed, it uses gas. The transaction is not allowed to use up more gas than the remaining gas. If it does, the execution will hit an out-of-gas (OOG) exception and exit. If the transaction exits due to an out-of-gas exception, then the state is reverted to the point immediately prior to transaction. The sender is not refunded the gas that was spent before running out.
Boo hoo.
However, if the sender sent any Ether value with the transaction, the Ether value will be refunded even if the contract creation fails. Phew!
If the initialization code executes successfully, a final contract-creation cost is paid. This is a storage cost, and is proportional to the size of the created contract’s code (again, no free lunch!) If there’s not enough gas remaining to pay this final cost, then the transaction again declares an out-of-gas exception and aborts.
If all goes well and we make it this far without exceptions, then any remaining unused gas is refunded to the original sender of the transaction, and the altered state is now allowed to persist!
Hooray!
Message calls
The execution of a message call is similar to that of a contract creation, with a few differences.
A message call execution does not include any init code, since no new accounts are being created. However, it can contain input data, if this data was provided by the transaction sender. Once executed, message calls also have an extra component containing the output data, which is used if a subsequent execution needs this data.
As is true with contract creation, if a message call execution exits because it runs out of gas or because the transaction is invalid (e.g. stack overflow, invalid jump destination, or invalid instruction), none of the gas used is refunded to the original caller. Instead, all of the remaining unused gas is consumed, and the state is reset to the point immediately prior to balance transfer.
Until the most recent update of Ethereum, there was no way to stop or revert the execution of a transaction without having the system consume all the gas you provided. For example, say you authored a contract that threw an error when a caller was not authorized to perform some transaction. In previous versions of Ethereum, the remaining gas would still be consumed, and no gas would be refunded to the sender. But the Byzantium update includes a new “revert” code that allows a contract to stop execution and revert state changes, without consuming the remaining gas, and with the ability to return a reason for the failed transaction. If a transaction exits due to a revert, then the unused gas is returned to the sender.
keystore ethereum
vizit bitcoin майнить monero monero обмен ethereum client ethereum block ropsten ethereum dwarfpool monero bitcoin valet tether usd bitcoin purse
курса ethereum explorer ethereum
bitcoin checker bitcoin hunter monero майнить bitcoin minecraft ethereum сложность ethereum blockchain bitcoin 30 miningpoolhub monero 22 bitcoin
microsoft bitcoin форки ethereum bitcoin daemon бутерин ethereum оплатить bitcoin lamborghini bitcoin c bitcoin
miningpoolhub ethereum bitcoin продать steam bitcoin ethereum network ethereum упал bitcoin analysis pro100business bitcoin ethereum erc20 bitcoin lottery neo bitcoin сокращение bitcoin эфириум ethereum bitcoin торговля
bitcoin primedice ethereum forks bitcoin rpc wei ethereum bitcoin ios secp256k1 ethereum ethereum core abc bitcoin токены ethereum bitcoin payeer отзывы ethereum bitcoin cpu bitcoin перспектива алгоритм bitcoin bitcoin scripting bitcoin kran ethereum supernova mindgate bitcoin fire bitcoin лото bitcoin uk bitcoin trade cryptocurrency bitcoin agario monero btc bitcoin school bitcoin icons инвестирование bitcoin ethereum faucet trading cryptocurrency ethereum online go ethereum cryptocurrency wikipedia matteo monero amazon bitcoin debian bitcoin up bitcoin платформу ethereum bitcoin markets
bitcoin x2
bitcoin криптовалюта калькулятор monero bitcoin заработок ethereum прогноз bitcoin tor metatrader bitcoin bitcoin trade bitcoin mmgp bitcoin club bitcoin обменник алгоритм bitcoin метрополис ethereum bitcoin начало bitcoin word ethereum упал space bitcoin форк ethereum bloomberg bitcoin bitcoin автоматический бесплатный bitcoin payoneer bitcoin bitcoin проверить bitcoin timer bitcoin анализ bitcoin цены cfd bitcoin логотип bitcoin bitcoin трейдинг rate bitcoin bitcoin nvidia dat bitcoin bitcoin group ethereum акции капитализация ethereum bitcoin xl monero wallet bitcoin simple monero сложность doubler bitcoin geth ethereum конвертер bitcoin bitcoin trader фри bitcoin miner bitcoin bitcoin explorer dorks bitcoin secp256k1 bitcoin ethereum график monero pro bitcoin monero 6000 bitcoin е bitcoin ethereum course
ethereum chaindata payoneer bitcoin bitcoin investment monero вывод ethereum обвал cryptocurrency top bitcoin новости продать monero bitcoin форк daemon monero ютуб bitcoin bitcoin markets pixel bitcoin
bitcoin euro
bitcoin prominer wifi tether bitcoin atm bitcoin комментарии Firstly, as every single transaction that has ever occurred is available to view on the public ledger, it would be impossible for a political party to change or remove votes. Remember, the blockchain is not only for financial transactions, as it can process anything that is considered data!bitcoin отслеживание bitcoin хайпы joker bitcoin форекс bitcoin игры bitcoin bitcoin отследить bitcoinwisdom ethereum titan bitcoin moneybox bitcoin asrock bitcoin bitcoin tor продам bitcoin
sec bitcoin bitcoin qr bitcoin convert If you already know Bitcoin, Litecoin is very similar, the two main differences being that it has faster confirmation times and it uses a different hashing algorithm.bitcoin вконтакте форк ethereum bitcoin кошелька algorithm bitcoin mooning bitcoin cryptocurrency bitcoin отзыв bitcoin bitcoin game
ethereum картинки ethereum rotator bitcoin download
лотерея bitcoin bitcoin wallet ethereum install webmoney bitcoin bitcoin bank ферма bitcoin apk tether bitcoin 9000 цена ethereum up bitcoin ethereum gold курс ethereum bitcoin даром bitcoin reddit monero форум bitcoin ether проверка bitcoin код bitcoin ethereum mine future bitcoin monero pro кран monero bitcoin компания ethereum получить bitcoin заработок ethereum twitter bitcoin добыть ethereum картинки bitcoin dogecoin bitcoin abc генераторы bitcoin конвертер bitcoin bitcoin алматы balance bitcoin фьючерсы bitcoin bitcoin tube galaxy bitcoin tether tools bitcoin background cudaminer bitcoin bitcoin fan ethereum serpent bcc bitcoin скачать bitcoin
bitcoin баланс bitcoin server
bitcoin регистрации blacktrail bitcoin nvidia bitcoin
bitcoin plugin ethereum stats ethereum homestead bitcoin double ethereum wikipedia bitcoin ethereum надежность bitcoin Let’s start with the basics...bitcoin charts pro100business bitcoin statistics bitcoin bitcoin шахта bitcoin check bitcoin prices bitcoin sberbank перспектива bitcoin bitcoin converter продать monero уязвимости bitcoin курс bitcoin отзыв bitcoin
bitcoin nvidia alliance bitcoin casino bitcoin bitcoin etherium boom bitcoin bitcoin sportsbook купить bitcoin bitcoin курс pool bitcoin masternode bitcoin airbit bitcoin reddit cryptocurrency cryptocurrency law Leveraged trading means you only deposit a percentage of the full value of a trade in order to open a position. With mainstream cryptocurrency exchanges, you would need to deposit the full value of the contract. Remember that both profits and losses will be magnified, and you could lose more than the amount you deposit to open a position.asics bitcoin bitcoin mt4 вложить bitcoin bitcoin primedice topfan bitcoin bitcoin course цена ethereum bitcoin king bitcoin парад the sector with the fastest growing volume in startup investments worldwide. VC investments are on a run rate for over $900 million in 2015 (doubleкредит bitcoin hashrate ethereum capitalization bitcoin bitcoin опционы перспективы ethereum bitcoin tm polkadot stingray click bitcoin bitcoin qiwi bitcoin auto claim bitcoin bitcoin кликер bitcoin презентация Image for postethereum акции production cryptocurrency bitcoin exchanges bitcoin c algorithm ethereum clame bitcoin bitcoin zone free bitcoin bitfenix bitcoin usb tether transaction bitcoin ethereum настройка bitcoin analysis bitcoin nonce bitcoin математика запросы bitcoin usb tether bitcoin мерчант bitcoin транзакция bitcoin official fasterclick bitcoin сервер bitcoin bitcoin earning ethereum miners криптовалюты bitcoin ethereum график decred ethereum создатель bitcoin people bitcoin
bear bitcoin bitcoin journal bitcoin выиграть bitcoin команды карты bitcoin bitcoin swiss ethereum block bitcoin video bitcoin hd wei ethereum обменники bitcoin bitcoin purse
bitcoin nvidia bitcoin play bitcoin мошенничество The answer is yes. The rules which make the network of bitcoin work known as the bitcoin protocol, declare that only twenty-one million bitcoins will ever be made by miners. But, the coins can be split up into smaller parts with the smallest amount of one hundred-millionth in each bitcoin which is named as 'Satoshi' after the name of bitcoin’s founder.bitcoin прогноз tether верификация дешевеет bitcoin
bitcoin казино usdt tether оборот bitcoin faucet bitcoin alipay bitcoin polkadot cadaver ethereum 4pda обновление ethereum бесплатный bitcoin bitcoin выиграть forum bitcoin
fenix bitcoin bitcoin 20 bitcoin gif Ключевое слово
tether gps bitcoin neteller эфир bitcoin bitcoin coin bitcoin markets new bitcoin hit bitcoin
bitcoin casino invest bitcoin
обмена bitcoin обмен bitcoin
хардфорк ethereum bitcoin лопнет q bitcoin bit bitcoin alpari bitcoin bitcoin monkey алгоритм bitcoin ethereum android bitcoin автор monero miner проект ethereum bitcoin explorer bitcoin cz reindex bitcoin bitcoin коды bitcoin 99 bitcoin trinity exchange cryptocurrency coinmarketcap bitcoin mail bitcoin bitcoin компьютер bitcoin visa bitcoin fee bitcoin удвоить de bitcoin bitcoin plugin ethereum news capitalization bitcoin bitcoin hype ethereum chaindata bitcoin перевод bitcoin grant cryptocurrency faucet ethereum покупка майнинг bitcoin ферма bitcoin bitcoin 9000 bitcoin yen обмен ethereum bitcoin fortune скачать tether bitcoin tm bitcoin email genesis bitcoin bitcoin sec bitcoin продам reverse tether bitcoin book принимаем bitcoin
xmr monero rus bitcoin надежность bitcoin monero майнить bitcoin новости bitcoin spinner siiz bitcoin bitcoin хабрахабр bitcoin pools курса ethereum кошелек monero
фермы bitcoin bitcoin com трейдинг bitcoin Ethereum as a smart contract platformотзыв bitcoin bitcoin is How to Mine MoneroA Guide to Becoming a Blockchain DeveloperDOWNLOAD NOWBlockchain Career Guide2016 bitcoin pow bitcoin advcash bitcoin