How an Ethereum account hold nounce, eth balance, contract code and storage?

Question

I am looking go-ethereum code and it is a bit hard to understand, how actually an account holds its information.

Based on Ethereum White Paper,

An Ethereum account contains four fields:

• The nonce
• The account's current ether balance
• The account's contract code, if present
• The account's storage (empty by default)

When I look at account type(/accounts/accounts.go) in go-ethereum, it only has Address and Url. I looked at Address type but there is not much information what I am looking for but I found StateDB has some more functions which are related the White Paper's explanation.

Could you explain Account and StateDB relationship or the mechanism how an account holds that information?

Answer 1

The account data is stored in the world state trie, with each leaf in the trie representing an account.

See: What are the storage and state tries?

The account data structure is RLP-encoded, and contains:

• the nonce;
• the balance;
• the storage root, which is a hash of the root of the account's storage trie;
• the code hash, which is a hash of the code associated with the account (i.e. contract code).

(See the rlp tag.)

This is represented in state_object.go as:

// Account is the Ethereum consensus representation of accounts.
// These objects are stored in the main account trie.
type Account struct {
    Nonce    uint64
    Balance  *big.Int
    Root     common.Hash // merkle root of the storage trie
    CodeHash []byte
}

Associated handling and functionality are mostly in the files in go-ethereum/core/state/ rather than go-ethereum/accounts/.