path: root/ethchain/state.go

package ethchain

import (
    "github.com/ethereum/eth-go/ethutil"
    "math/big"
)

// States within the ethereum protocol are used to store anything
// within the merkle trie. States take care of caching and storing
// nested states. It's the general query interface to retrieve:
// * Contracts
// * Accounts
type State struct {
    // The trie for this structure
    trie *ethutil.Trie
    // Nested states
    states map[string]*State
}

// Create a new state from a given trie
func NewState(trie *ethutil.Trie) *State {
    return &State{trie: trie, states: make(map[string]*State)}
}

// Resets the trie and all siblings
func (s *State) Reset() {
    s.trie.Undo()

    // Reset all nested states
    for _, state := range s.states {
        state.Reset()
    }
}

// Syncs the trie and all siblings
func (s *State) Sync() {
    // Sync all nested states
    for _, state := range s.states {
        state.Sync()
    }

    s.trie.Sync()
}

// Purges the current trie.
func (s *State) Purge() int {
    return s.trie.NewIterator().Purge()
}

// XXX Deprecated
func (s *State) GetContract(addr []byte) *StateObject {
    data := s.trie.Get(string(addr))
    if data == "" {
        return nil
    }

    // build contract
    contract := NewStateObjectFromBytes(addr, []byte(data))

    // Check if there's a cached state for this contract
    cachedState := s.states[string(addr)]
    if cachedState != nil {
        contract.state = cachedState
    } else {
        // If it isn't cached, cache the state
        s.states[string(addr)] = contract.state
    }

    return contract
}

func (s *State) GetStateObject(addr []byte) *StateObject {
    data := s.trie.Get(string(addr))
    if data == "" {
        return nil
    }

    stateObject := NewStateObjectFromBytes(addr, []byte(data))

    // Check if there's a cached state for this contract
    cachedStateObject := s.states[string(addr)]
    if cachedStateObject != nil {
        stateObject.state = cachedStateObject
    } else {
        // If it isn't cached, cache the state
        s.states[string(addr)] = stateObject.state
    }

    return stateObject
}

func (s *State) SetStateObject(stateObject *StateObject) {
    s.states[string(stateObject.address)] = stateObject.state

    s.UpdateStateObject(stateObject)
}

func (s *State) GetAccount(addr []byte) (account *StateObject) {
    data := s.trie.Get(string(addr))
    if data == "" {
        account = NewAccount(addr, big.NewInt(0))
    } else {
        account = NewStateObjectFromBytes(addr, []byte(data))
    }

    return
}

func (s *State) Cmp(other *State) bool {
    return s.trie.Cmp(other.trie)
}

func (s *State) Copy() *State {
    return NewState(s.trie.Copy())
}

type ObjType byte

const (
    NilTy ObjType = iota
    AccountTy
    ContractTy

    UnknownTy
)

/*
// Returns the object stored at key and the type stored at key
// Returns nil if nothing is stored
func (s *State) GetStateObject(key []byte) (*ethutil.Value, ObjType) {
    // Fetch data from the trie
    data := s.trie.Get(string(key))
    // Returns the nil type, indicating nothing could be retrieved.
    // Anything using this function should check for this ret val
    if data == "" {
        return nil, NilTy
    }

    var typ ObjType
    val := ethutil.NewValueFromBytes([]byte(data))
    // Check the length of the retrieved value.
    // Len 2 = Account
    // Len 3 = Contract
    // Other = invalid for now. If other types emerge, add them here
    if val.Len() == 2 {
        typ = AccountTy
    } else if val.Len() == 3 {
        typ = ContractTy
    } else {
        typ = UnknownTy
    }

    return val, typ
}
*/

// Updates any given state object
func (s *State) UpdateStateObject(object *StateObject) {
    addr := object.Address()

    if object.state != nil {
        s.states[string(addr)] = object.state
    }

    s.trie.Update(string(addr), string(object.RlpEncode()))
}

func (s *State) Put(key, object []byte) {
    s.trie.Update(string(key), string(object))
}

func (s *State) Root() interface{} {
    return s.trie.Root
}