package transfer import ( "context" "math/big" "sort" "sync" "github.com/ethereum/go-ethereum/common" ) type nonceRange struct { nonce int64 max *big.Int min *big.Int } type balanceCache struct { // balances maps an address to a map of a block number and the balance of this particular address balances map[common.Address]map[*big.Int]*big.Int nonces map[common.Address]map[*big.Int]*int64 nonceRanges map[common.Address]map[int64]nonceRange sortedRanges map[common.Address][]nonceRange rw sync.RWMutex } type BalanceCache interface { BalanceAt(ctx context.Context, client BalanceReader, account common.Address, blockNumber *big.Int) (*big.Int, error) NonceAt(ctx context.Context, client BalanceReader, account common.Address, blockNumber *big.Int) (*int64, error) } func (b *balanceCache) ReadCachedBalance(account common.Address, blockNumber *big.Int) *big.Int { b.rw.RLock() defer b.rw.RUnlock() return b.balances[account][blockNumber] } func (b *balanceCache) addBalanceToCache(account common.Address, blockNumber *big.Int, balance *big.Int) { b.rw.Lock() defer b.rw.Unlock() _, exists := b.balances[account] if !exists { b.balances[account] = make(map[*big.Int]*big.Int) } b.balances[account][blockNumber] = balance } func (b *balanceCache) BalanceAt(ctx context.Context, client BalanceReader, account common.Address, blockNumber *big.Int) (*big.Int, error) { cachedBalance := b.ReadCachedBalance(account, blockNumber) if cachedBalance != nil { return cachedBalance, nil } balance, err := client.BalanceAt(ctx, account, blockNumber) if err != nil { return nil, err } b.addBalanceToCache(account, blockNumber, balance) return balance, nil } func (b *balanceCache) ReadCachedNonce(account common.Address, blockNumber *big.Int) *int64 { b.rw.RLock() defer b.rw.RUnlock() return b.nonces[account][blockNumber] } func (b *balanceCache) sortRanges(account common.Address) { keys := make([]int, 0, len(b.nonceRanges[account])) for k := range b.nonceRanges[account] { keys = append(keys, int(k)) } sort.Ints(keys) ranges := []nonceRange{} for _, k := range keys { r := b.nonceRanges[account][int64(k)] ranges = append(ranges, r) } b.sortedRanges[account] = ranges } func (b *balanceCache) findNonceInRange(account common.Address, block *big.Int) *int64 { for k := range b.sortedRanges[account] { nr := b.sortedRanges[account][k] cmpMin := nr.min.Cmp(block) if cmpMin == 1 { return nil } else if cmpMin == 0 { return &nr.nonce } else { cmpMax := nr.max.Cmp(block) if cmpMax >= 0 { return &nr.nonce } } } return nil } func (b *balanceCache) updateNonceRange(account common.Address, blockNumber *big.Int, nonce *int64) { _, exists := b.nonceRanges[account] if !exists { b.nonceRanges[account] = make(map[int64]nonceRange) } nr, exists := b.nonceRanges[account][*nonce] if !exists { r := nonceRange{ max: big.NewInt(0).Set(blockNumber), min: big.NewInt(0).Set(blockNumber), nonce: *nonce, } b.nonceRanges[account][*nonce] = r } else { if nr.max.Cmp(blockNumber) == -1 { nr.max.Set(blockNumber) } if nr.min.Cmp(blockNumber) == 1 { nr.min.Set(blockNumber) } b.nonceRanges[account][*nonce] = nr b.sortRanges(account) } } func (b *balanceCache) addNonceToCache(account common.Address, blockNumber *big.Int, nonce *int64) { b.rw.Lock() defer b.rw.Unlock() _, exists := b.nonces[account] if !exists { b.nonces[account] = make(map[*big.Int]*int64) } b.nonces[account][blockNumber] = nonce b.updateNonceRange(account, blockNumber, nonce) } func (b *balanceCache) NonceAt(ctx context.Context, client BalanceReader, account common.Address, blockNumber *big.Int) (*int64, error) { cachedNonce := b.ReadCachedNonce(account, blockNumber) if cachedNonce != nil { return cachedNonce, nil } rangeNonce := b.findNonceInRange(account, blockNumber) if rangeNonce != nil { return rangeNonce, nil } nonce, err := client.NonceAt(ctx, account, blockNumber) if err != nil { return nil, err } int64Nonce := int64(nonce) b.addNonceToCache(account, blockNumber, &int64Nonce) return &int64Nonce, nil } func newBalanceCache() *balanceCache { return &balanceCache{ balances: make(map[common.Address]map[*big.Int]*big.Int), nonces: make(map[common.Address]map[*big.Int]*int64), nonceRanges: make(map[common.Address]map[int64]nonceRange), sortedRanges: make(map[common.Address][]nonceRange), } }