l2geth: add core access list type

l2geth/core/state/access_list.go

+// Copyright 2020 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 (
+	"github.com/ethereum-optimism/optimism/l2geth/common"
+)
+
+type accessList struct {
+	addresses map[common.Address]int
+	slots     []map[common.Hash]struct{}
+}
+
+// ContainsAddress returns true if the address is in the access list.
+func (al *accessList) ContainsAddress(address common.Address) bool {
+	_, ok := al.addresses[address]
+	return ok
+}
+
+// Contains checks if a slot within an account is present in the access list, returning
+// separate flags for the presence of the account and the slot respectively.
+func (al *accessList) Contains(address common.Address, slot common.Hash) (addressPresent bool, slotPresent bool) {
+	idx, ok := al.addresses[address]
+	if !ok {
+		// no such address (and hence zero slots)
+		return false, false
+	}
+	if idx == -1 {
+		// address yes, but no slots
+		return true, false
+	}
+	_, slotPresent = al.slots[idx][slot]
+	return true, slotPresent
+}
+
+// newAccessList creates a new accessList.
+func newAccessList() *accessList {
+	return &accessList{
+		addresses: make(map[common.Address]int),
+	}
+}
+
+// Copy creates an independent copy of an accessList.
+func (a *accessList) Copy() *accessList {
+	cp := newAccessList()
+	for k, v := range a.addresses {
+		cp.addresses[k] = v
+	}
+	cp.slots = make([]map[common.Hash]struct{}, len(a.slots))
+	for i, slotMap := range a.slots {
+		newSlotmap := make(map[common.Hash]struct{}, len(slotMap))
+		for k := range slotMap {
+			newSlotmap[k] = struct{}{}
+		}
+		cp.slots[i] = newSlotmap
+	}
+	return cp
+}
+
+// AddAddress adds an address to the access list, and returns 'true' if the operation
+// caused a change (addr was not previously in the list).
+func (al *accessList) AddAddress(address common.Address) bool {
+	if _, present := al.addresses[address]; present {
+		return false
+	}
+	al.addresses[address] = -1
+	return true
+}
+
+// AddSlot adds the specified (addr, slot) combo to the access list.
+// Return values are:
+// - address added
+// - slot added
+// For any 'true' value returned, a corresponding journal entry must be made.
+func (al *accessList) AddSlot(address common.Address, slot common.Hash) (addrChange bool, slotChange bool) {
+	idx, addrPresent := al.addresses[address]
+	if !addrPresent || idx == -1 {
+		// Address not present, or addr present but no slots there
+		al.addresses[address] = len(al.slots)
+		slotmap := map[common.Hash]struct{}{slot: {}}
+		al.slots = append(al.slots, slotmap)
+		return !addrPresent, true
+	}
+	// There is already an (address,slot) mapping
+	slotmap := al.slots[idx]
+	if _, ok := slotmap[slot]; !ok {
+		slotmap[slot] = struct{}{}
+		// Journal add slot change
+		return false, true
+	}
+	// No changes required
+	return false, false
+}
+
+// DeleteSlot removes an (address, slot)-tuple from the access list.
+// This operation needs to be performed in the same order as the addition happened.
+// This method is meant to be used  by the journal, which maintains ordering of
+// operations.
+func (al *accessList) DeleteSlot(address common.Address, slot common.Hash) {
+	idx, addrOk := al.addresses[address]
+	// There are two ways this can fail
+	if !addrOk {
+		panic("reverting slot change, address not present in list")
+	}
+	slotmap := al.slots[idx]
+	delete(slotmap, slot)
+	// If that was the last (first) slot, remove it
+	// Since additions and rollbacks are always performed in order,
+	// we can delete the item without worrying about screwing up later indices
+	if len(slotmap) == 0 {
+		al.slots = al.slots[:idx]
+		al.addresses[address] = -1
+	}
+}
+
+// DeleteAddress removes an address from the access list. This operation
+// needs to be performed in the same order as the addition happened.
+// This method is meant to be used  by the journal, which maintains ordering of
+// operations.
+func (al *accessList) DeleteAddress(address common.Address) {
+	delete(al.addresses, address)
+}