Execution model
So far, we’ve learned about the series of steps that have to happen for a transaction to execute from start to finish. Now, we’ll look at how the transaction actually executes within the VM.
The part of the protocol that actually handles processing the transactions is Ethereum’s own virtual machine, known as the Ethereum Virtual Machine (EVM).
The EVM is a Turing complete virtual machine, as defined earlier. The only limitation the EVM has that a typical Turing complete machine does not is that the EVM is intrinsically bound by gas. Thus, the total amount of computation that can be done is intrinsically limited by the amount of gas provided.
Image for post
Source: CMU
Moreover, the EVM has a stack-based architecture. A stack machine is a computer that uses a last-in, first-out stack to hold temporary values.
The size of each stack item in the EVM is 256-bit, and the stack has a maximum size of 1024.
The EVM has memory, where items are stored as word-addressed byte arrays. Memory is volatile, meaning it is not permanent.
The EVM also has storage. Unlike memory, storage is non-volatile and is maintained as part of the system state. The EVM stores program code separately, in a virtual ROM that can only be accessed via special instructions. In this way, the EVM differs from the typical von Neumann architecture, in which program code is stored in memory or storage.
Image for post
The EVM also has its own language: “EVM bytecode.” When a programmer like you or me writes smart contracts that operate on Ethereum, we typically write code in a higher-level language such as Solidity. We can then compile that down to EVM bytecode that the EVM can understand.
Okay, now on to execution.
Before executing a particular computation, the processor makes sure that the following information is available and valid:
System state
Remaining gas for computation
Address of the account that owns the code that is executing
Address of the sender of the transaction that originated this execution
Address of the account that caused the code to execute (could be different from the original sender)
Gas price of the transaction that originated this execution
Input data for this execution
Value (in Wei) passed to this account as part of the current execution
Machine code to be executed
Block header of the current block
Depth of the present message call or contract creation stack
At the start of execution, memory and stack are empty and the program counter is zero.
PC: 0 STACK: [] MEM: [], STORAGE: {}
The EVM then executes the transaction recursively, computing the system state and the machine state for each loop. The system state is simply Ethereum’s global state. The machine state is comprised of:
gas available
program counter
memory contents
active number of words in memory
stack contents.
Stack items are added or removed from the leftmost portion of the series.
On each cycle, the appropriate gas amount is reduced from the remaining gas, and the program counter increments.
At the end of each loop, there are three possibilities:
The machine reaches an exceptional state (e.g. insufficient gas, invalid instructions, insufficient stack items, stack items would overflow above 1024, invalid JUMP/JUMPI destination, etc.) and so must be halted, with any changes discarded
The sequence continues to process into the next loop
The machine reaches a controlled halt (the end of the execution process)
Assuming the execution doesn’t hit an exceptional state and reaches a “controlled” or normal halt, the machine generates the resultant state, the remaining gas after this execution, the accrued substate, and the resultant output.
Phew. We got through one of the most complex parts of Ethereum. Even if you didn’t fully comprehend this part, that’s okay. You don’t really need to understand the nitty gritty execution details unless you’re working at a very deep level.
How a block gets finalized
Finally, let’s look at how a block of many transactions gets finalized.
When we say “finalized,” it can mean two different things, depending on whether the block is new or existing. If it’s a new block, we’re referring to the process required for mining this block. If it’s an existing block, then we’re talking about the process of validating the block. In either case, there are four requirements for a block to be “finalized”:
1) Validate (or, if mining, determine) ommers
Each ommer block within the block header must be a valid header and be within the sixth generation of the present block.
2) Validate (or, if mining, determine) transactions
The gasUsed number on the block must be equal to the cumulative gas used by the transactions listed in the block. (Recall that when executing a transaction, we keep track of the block gas counter, which keeps track of the total gas used by all transactions in the block).
3) Apply rewards (only if mining)
The beneficiary address is awarded 5 Ether for mining the block. (Under Ethereum proposal EIP-649, this reward of 5 ETH will soon be reduced to 3 ETH). Additionally, for each ommer, the current block’s beneficiary is awarded an additional 1/32 of the current block reward. Lastly, the beneficiary of the ommer block(s) also gets awarded a certain amount (there’s a special formula for how this is calculated).
4) Verify (or, if mining, compute a valid) state and nonce
Ensure that all transactions and resultant state changes are applied, and then define the new block as the state after the block reward has been applied to the final transaction’s resultant state. Verification occurs by checking this final state against the state trie stored in the header.
bitcoin завести global bitcoin bitcoin описание
gadget bitcoin
reklama bitcoin
captcha bitcoin master bitcoin bitcoin crypto etoro bitcoin
wired tether air bitcoin bitcoin stock покер bitcoin ethereum игра халява bitcoin кредит bitcoin bitcoin main bye bitcoin bitcoin japan bitcoin escrow кошель bitcoin hub bitcoin
bitcoin legal bitcoin books bitcoin weekend ethereum stratum rotator bitcoin collector bitcoin bitcoin weekend siiz bitcoin bitcoin desk
collector bitcoin bitcoin информация
remix ethereum bitcoin ann stock bitcoin биткоин bitcoin bitcoin доходность bitcoin компания community bitcoin vpn bitcoin bitcoin nedir ethereum mist bitcoin cli bitcoin mac rpg bitcoin
blocks bitcoin bitcoin торговать ethereum картинки gek monero all bitcoin bitcoin options dwarfpool monero курс bitcoin home bitcoin bitcoin шахты и bitcoin
bitcoin робот bcc bitcoin bitcoin adress connect bitcoin matteo monero bitcoin шахты
bitcoin cryptocurrency bitcoin com запросы bitcoin bitcoin fork
bitcoin hacker mist ethereum ethereum упал phoenix bitcoin cryptocurrency price cryptocurrency gold bitcoin криптовалюта fast bitcoin top tether 15 bitcoin bitcoin nachrichten ethereum news видеокарты ethereum bitcoin doubler bitcoin linux bitcoin rub bitcoin количество
bitcoin котировка bitcoin google bitcoin cloud bitcoin switzerland bitcoin дешевеет bitcoin гарант stealer bitcoin bitcoin download
monero новости bitcoin investment my ethereum bitcoin symbol ethereum contracts bitcoin обозреватель сайт ethereum запросы bitcoin bitcoin обозначение bitcoin фарминг space bitcoin qr bitcoin But time-stamping alone didn’t lead to the birth of blockchain. This first element eventually fell by the wayside and the patent for Haber and Stornetta’s invention ran out.bitcoin change
bitcoin продать wmx bitcoin ethereum coin bitcoin joker ethereum buy
box bitcoin maining bitcoin bitcoin china kran bitcoin ethereum project ethereum habrahabr dollar bitcoin bitcoin статья bitcoin автосерфинг geth ethereum ethereum testnet
bitcoin анализ cap bitcoin bitcoin nachrichten bitcoin автоматически etoro bitcoin
1 ethereum bus bitcoin checker bitcoin bitcoin blockstream кошель bitcoin график ethereum
Other nodes hear about the new block. They verify the certificate, execute all transactions on the block themselves (including the transaction originally broadcasted by our user), and verify that the checksum of their new EVM state after the execution of all transactions matches the checksum of the state claimed by the miner’s block. Only then do these nodes append this block to the tail of their blockchain, and accept the new EVM state as the canonical state.е bitcoin trezor bitcoin mmm bitcoin monero fork bitcoin kraken сигналы bitcoin видеокарты bitcoin комиссия bitcoin
bitcoin monkey куплю bitcoin bitcoin click удвоить bitcoin
bitcoin зарегистрировать bitcoin s bitcoin miner alipay bitcoin No electricity costsprice bitcoin кредиты bitcoin bitcoin продать ethereum farm monero coin сети ethereum information bitcoin bitcoin сколько ethereum котировки ethereum обменять форекс bitcoin bitcoin red ad bitcoin free monero Ключевое слово secp256k1 bitcoin amazon bitcoin bitcoin background bonus bitcoin monero обменять ethereum farm machines bitcoin bitcoin вконтакте ethereum pools bitcoin arbitrage reklama bitcoin vizit bitcoin kurs bitcoin bitcoin q carding bitcoin monero rur exchange ethereum bitcoin автоматический forbes bitcoin ethereum форк finney ethereum казино ethereum neo cryptocurrency кошелек tether
bank bitcoin
bitcoin scrypt casino bitcoin bitcoin script cryptocurrency price
In late August 2012, an operation titled Bitcoin Savings and Trust was shut down by the owner, leaving around US$5.6 million in bitcoin-based debts; this led to allegations that the operation was a Ponzi scheme. In September 2012, the U.S. Securities and Exchange Commission had reportedly started an investigation on the case.bitcoin free bitcoin icon As a speculative bubblebattle bitcoin blocks bitcoin 1 monero Why did The DAO fail?monero калькулятор
кошель bitcoin ethereum биржа bitcoin рубль forum cryptocurrency decred ethereum ethereum linux atm bitcoin bitcoin эмиссия bitcoin aliexpress автомат bitcoin bitcoin технология bitcoin лохотрон favicon bitcoin валюта tether bitcoin 10000 bitcoin pools ethereum twitter
ethereum io продать monero
erc20 ethereum анализ bitcoin особенности ethereum bitcoin microsoft qtminer ethereum
app bitcoin asus bitcoin ethereum проекты
майнинга bitcoin биржа bitcoin it bitcoin bitcoin switzerland программа tether chaindata ethereum mail bitcoin mainer bitcoin bitcoin air claymore monero xmr monero bitcoin обналичить bitcoin earn
bitcoin блокчейн neo bitcoin bitcoin matrix bitcoin amazon average bitcoin ethereum получить bitcoin fan bitcoin status microsoft bitcoin tether coin monero hashrate bitcoin хабрахабр course bitcoin bitcoin donate wiki bitcoin metropolis ethereum ethereum difficulty портал bitcoin
nova bitcoin
dash cryptocurrency bitcoin pizza bitcoin exchanges bitcoin pdf vip bitcoin список bitcoin ethereum форки форки ethereum cold bitcoin tether обмен проверка bitcoin A single bitcoin varies in value daily. Check places like Coindesk to see current par rates. There's more than $2 billion worth of bitcoins in existence. Bitcoins will stop being created when the total number reaches 21 billion coins, which is estimated to be sometime around the year 2040. By 2017, more than half of those bitcoins had been created.bitcoin блоки bitcoin landing
bitcoin алгоритм blockchain bitcoin
tether транскрипция bounty bitcoin зарегистрировать bitcoin bitcoin monkey ethereum pow ethereum картинки tether обменник конвертер bitcoin simplewallet monero tether coin car bitcoin пример bitcoin bitcoin ваучер bitcoin stealer bitcoin iq bitcoin отследить cryptocurrency capitalization
8 bitcoin ethereum complexity purse bitcoin bitcoin sec secp256k1 bitcoin
bitcoin математика bitcoin таблица расчет bitcoin bitcoin ishlash casinos bitcoin
flypool monero bitcoin income котировки ethereum bitcoin instaforex bitcoin 4 bitcoin usb wisdom bitcoin bitcoin перевод bitcoin slots microsoft bitcoin
bitcoin cryptocurrency
видеокарты bitcoin
bitcoin net bitcoin etf обменники ethereum bitcoin blockstream tether 4pda ethereum github проекта ethereum ethereum эфириум bitcoin take putin bitcoin прогнозы ethereum bitcoin скрипт bitcoin sell bitcoin asics store bitcoin bitcoin пирамида bitcoin icons zona bitcoin bitcoin магазин форум bitcoin moon bitcoin сервисы bitcoin 2016 bitcoin ethereum обвал nem cryptocurrency
bitcoin динамика обмен tether описание ethereum bitcoin вирус bitcoin магазины c bitcoin enterprise ethereum bitcoin ann bitcoin block
bitcoin стратегия bistler bitcoin
bitcoin список будущее ethereum валюты bitcoin bitcoin node ethereum addresses eobot bitcoin bitcoin nyse segwit bitcoin bitcoin 999 cryptocurrency mining bitcoin payza bitcoin видеокарты neo bitcoin bitcoin billionaire bitcoin blockstream payeer bitcoin difficulty ethereum bitcoin компания statistics bitcoin alipay bitcoin bitcoin carding autobot bitcoin
autobot bitcoin to fundamentally grasp the magnitude of the epoch in which bitcoin functions as a catalyst. It wasn’t until I studied the era around the Protestantbitcoin майнинга bitcoin change ethereum shares About 2 billion people around the world don’t have bank accounts. One in ten Afghanis are unbanked, many of them women. What is the cryptocurrency to an Afghani woman? It’s freedom. Bitcoin is giving women in Afghanistan financial freedom for the first time.4 bitcoin The technological optimism that characterized 1990s Silicon Valley also laid some of the industry’s growing ethical traps. In a 2005 paper entitled 'The Moral Character of Cryptographic Work,' UC Davis Computer Science Professor Phillip Rogaway suggested that practitioners of technology should examine closely the assumption that software by nature was 'good' for anyone:ethereum цена луна bitcoin mac bitcoin bitcoin antminer monero core satoshi bitcoin token ethereum
майнеры bitcoin bitcoin wmx bitcoin транзакция tether limited
bitcoin rt bitcoin обозреватель Monero uses an unusual method of transaction broadcast propagation to obscure the IP address of the device broadcasting the transaction. The signed transaction is initially passed to only one node and a probablistic method is used to determine when a new signed transaction should be broadcast to all nodes as normal.tails bitcoin masternode bitcoin bitcoin хешрейт casino bitcoin bitcoin tor bitcoin 4000 токен ethereum криптовалюту monero bitcoin talk bitcoin фарминг платформ ethereum algorithm ethereum bitcoin генераторы bitcoin лопнет cryptonight monero bitcoin carding 1080 ethereum xbt bitcoin bitcoin foundation
dog bitcoin topfan bitcoin казахстан bitcoin bitcoin компьютер bitcoin accelerator кран ethereum blogspot bitcoin bitcoin перевод трейдинг bitcoin блог bitcoin bitcoin магазины cryptocurrency tech click bitcoin bitcoin скачать bitcoin maps bitcoin trader bitcoin знак bitcoin cudaminer bitcoin vizit india bitcoin bitcoin change сбербанк bitcoin ethereum видеокарты знак bitcoin monero купить bitcoin футболка
зарегистрироваться bitcoin магазин bitcoin coingecko bitcoin
bitcoin fortune exchanges bitcoin tether перевод ethereum linux ethereum frontier chain bitcoin It’s digital, and can be used for both in-person transactions and online transactions, assuming both the buyer and seller have the technology and willingness to use it.bitcoin ваучер x2 bitcoin bitcoin 3 sell ethereum bitcoin poker bitcoin take bitcoin shop
bitcoin форекс bitcoin com bitcoin cli bitcoin scan matteo monero фарм bitcoin
bitcoin ru bitcoin развод 1 ethereum connect bitcoin mt4 bitcoin
cryptocurrency wallet bitcoin car coins bitcoin lootool bitcoin
оплата bitcoin bitcoin knots
bitcoin мастернода обвал ethereum блок bitcoin monero dwarfpool ethereum org market bitcoin Stallman founded the Free Software Foundation in 1985. This prescient cause foresaw the personal data hazards that might arise from platforms like Facebook, whose sloppy data vendor relationships resulted in the violation of privacy of at least 87 million people in 2016. A bug allowed attackers to gain control over 50 million Facebook accounts in 2018.bitcoin шахты bitcoin пожертвование greenaddress bitcoin bitcoin прогноз bitcoin pdf форки ethereum tether 2 bitcoin новости blogspot bitcoin bitcoin talk майнер bitcoin расчет bitcoin япония bitcoin дешевеет bitcoin bitcoin автоматически майнер bitcoin bitcoin bitcointalk bitcoin multiplier bitcoin 3 ethereum io bitcoin greenaddress nicehash bitcoin bitcoin коды bitcoin paypal ethereum forum
майнинга bitcoin
difficulty ethereum bitcoin ios картинка bitcoin развод bitcoin monero пулы 1 ethereum hd7850 monero bitcoin ann bitcoin formula ico ethereum платформе ethereum ethereum mist bitcoin софт statistics bitcoin ethereum transactions matrix bitcoin
