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

    manifest *Manifest
}

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

// 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())
}

// 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()))
    s.manifest.AddObjectChange(object)
}

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

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

// Object manifest
//
// The object manifest is used to keep changes to the state so we can keep track of the changes
// that occurred during a state transitioning phase.
type Manifest struct {
    // XXX These will be handy in the future. Not important for now.
    objectAddresses  map[string]bool
    storageAddresses map[string]map[string]bool

    objectChanges  map[string]*StateObject
    storageChanges map[string]map[string]*big.Int
}

func NewManifest() *Manifest {
    m := &Manifest{objectAddresses: make(map[string]bool), storageAddresses: make(map[string]map[string]bool)}
    m.Reset()

    return m
}

func (m *Manifest) Reset() {
    m.objectChanges = make(map[string]*StateObject)
    m.storageChanges = make(map[string]map[string]*big.Int)
}

func (m *Manifest) AddObjectChange(stateObject *StateObject) {
    m.objectChanges[string(stateObject.Address())] = stateObject
}

func (m *Manifest) AddStorageChange(stateObject *StateObject, storageAddr []byte, storage *big.Int) {
    if m.storageChanges[string(stateObject.Address())] == nil {
        m.storageChanges[string(stateObject.Address())] = make(map[string]*big.Int)
    }

    m.storageChanges[string(stateObject.Address())][string(storageAddr)] = storage
}