path: root/core/state/managed_state.go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package state

import (
    "sync"

    "github.com/dexon-foundation/dexon/common"
)

type account struct {
    stateObject *stateObject
    nstart      uint64
    nonces      []bool
}

type ManagedState struct {
    *StateDB

    mu sync.RWMutex

    accounts map[common.Address]*account
}

// ManagedState returns a new managed state with the statedb as it's backing layer
func ManageState(statedb *StateDB) *ManagedState {
    return &ManagedState{
        StateDB:  statedb.Copy(),
        accounts: make(map[common.Address]*account),
    }
}

// SetState sets the backing layer of the managed state
func (ms *ManagedState) SetState(statedb *StateDB) {
    ms.mu.Lock()
    defer ms.mu.Unlock()
    ms.StateDB = statedb
}

// RemoveNonce removed the nonce from the managed state and all future pending nonces
func (ms *ManagedState) RemoveNonce(addr common.Address, n uint64) {
    if ms.hasAccount(addr) {
        ms.mu.Lock()
        defer ms.mu.Unlock()

        account := ms.getAccount(addr)
        if n-account.nstart <= uint64(len(account.nonces)) {
            reslice := make([]bool, n-account.nstart)
            copy(reslice, account.nonces[:n-account.nstart])
            account.nonces = reslice
        }
    }
}

// NewNonce returns the new canonical nonce for the managed account
func (ms *ManagedState) NewNonce(addr common.Address) uint64 {
    ms.mu.Lock()
    defer ms.mu.Unlock()

    account := ms.getAccount(addr)
    for i, nonce := range account.nonces {
        if !nonce {
            return account.nstart + uint64(i)
        }
    }
    account.nonces = append(account.nonces, true)

    return uint64(len(account.nonces)-1) + account.nstart
}

// GetNonce returns the canonical nonce for the managed or unmanaged account.
//
// Because GetNonce mutates the DB, we must take a write lock.
func (ms *ManagedState) GetNonce(addr common.Address) uint64 {
    ms.mu.Lock()
    defer ms.mu.Unlock()

    if ms.hasAccount(addr) {
        account := ms.getAccount(addr)
        return uint64(len(account.nonces)) + account.nstart
    } else {
        return ms.StateDB.GetNonce(addr)
    }
}

// SetNonce sets the new canonical nonce for the managed state
func (ms *ManagedState) SetNonce(addr common.Address, nonce uint64) {
    ms.mu.Lock()
    defer ms.mu.Unlock()

    so := ms.GetOrNewStateObject(addr)
    so.SetNonce(nonce)

    ms.accounts[addr] = newAccount(so)
}

// HasAccount returns whether the given address is managed or not
func (ms *ManagedState) HasAccount(addr common.Address) bool {
    ms.mu.RLock()
    defer ms.mu.RUnlock()
    return ms.hasAccount(addr)
}

func (ms *ManagedState) hasAccount(addr common.Address) bool {
    _, ok := ms.accounts[addr]
    return ok
}

// populate the managed state
func (ms *ManagedState) getAccount(addr common.Address) *account {
    if account, ok := ms.accounts[addr]; !ok {
        so := ms.GetOrNewStateObject(addr)
        ms.accounts[addr] = newAccount(so)
    } else {
        // Always make sure the state account nonce isn't actually higher
        // than the tracked one.
        so := ms.StateDB.getStateObject(addr)
        if so != nil && uint64(len(account.nonces))+account.nstart < so.Nonce() {
            ms.accounts[addr] = newAccount(so)
        }

    }

    return ms.accounts[addr]
}

func newAccount(so *stateObject) *account {
    return &account{so, so.Nonce(), nil}
}