Merge branch 'develop' into inphi/fpp-boot

go.mod

@@ -34,6 +34,7 @@ require (
 	github.com/urfave/cli/v2 v2.17.2-0.20221006022127-8f469abc00aa
 	golang.org/x/crypto v0.6.0
 	golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb
+	golang.org/x/sync v0.1.0
 	golang.org/x/term v0.5.0
 	golang.org/x/time v0.0.0-20220922220347-f3bd1da661af
 )
@@ -176,7 +177,6 @@ require (
 	go.uber.org/zap v1.24.0 // indirect
 	golang.org/x/mod v0.8.0 // indirect
 	golang.org/x/net v0.7.0 // indirect
-	golang.org/x/sync v0.1.0 // indirect
 	golang.org/x/sys v0.5.0 // indirect
 	golang.org/x/text v0.7.0 // indirect
 	golang.org/x/tools v0.6.0 // indirect

op-batcher/batcher/channel_manager.go

@@ -199,6 +199,11 @@ func (s *channelManager) TxData(l1Head eth.BlockID) (txData, error) {
 		return txData{}, io.EOF
 	}
 
+	// we have blocks, but we cannot add them to the channel right now
+	if s.pendingChannel != nil && s.pendingChannel.IsFull() {
+		return txData{}, io.EOF
+	}
+
 	if err := s.ensurePendingChannel(l1Head); err != nil {
 		return txData{}, err
 	}

op-batcher/batcher/config.go

@@ -26,8 +26,9 @@ type Config struct {
 	RollupNode *sources.RollupClient
 	TxManager  txmgr.TxManager
 
-	NetworkTimeout time.Duration
-	PollInterval   time.Duration
+	NetworkTimeout         time.Duration
+	PollInterval           time.Duration
+	MaxPendingTransactions uint64
 
 	// RollupConfig is queried at startup
 	Rollup *rollup.Config
@@ -76,6 +77,10 @@ type CLIConfig struct {
 	// and creating a new batch.
 	PollInterval time.Duration
 
+	// MaxPendingTransactions is the maximum number of concurrent pending
+	// transactions sent to the transaction manager.
+	MaxPendingTransactions uint64
+
 	// MaxL1TxSize is the maximum size of a batch tx submitted to L1.
 	MaxL1TxSize uint64
 
@@ -128,16 +133,17 @@ func NewConfig(ctx *cli.Context) CLIConfig {
 		PollInterval:    ctx.GlobalDuration(flags.PollIntervalFlag.Name),
 
 		/* Optional Flags */
-		MaxChannelDuration: ctx.GlobalUint64(flags.MaxChannelDurationFlag.Name),
-		MaxL1TxSize:        ctx.GlobalUint64(flags.MaxL1TxSizeBytesFlag.Name),
-		TargetL1TxSize:     ctx.GlobalUint64(flags.TargetL1TxSizeBytesFlag.Name),
-		TargetNumFrames:    ctx.GlobalInt(flags.TargetNumFramesFlag.Name),
-		ApproxComprRatio:   ctx.GlobalFloat64(flags.ApproxComprRatioFlag.Name),
-		Stopped:            ctx.GlobalBool(flags.StoppedFlag.Name),
-		TxMgrConfig:        txmgr.ReadCLIConfig(ctx),
-		RPCConfig:          rpc.ReadCLIConfig(ctx),
-		LogConfig:          oplog.ReadCLIConfig(ctx),
-		MetricsConfig:      opmetrics.ReadCLIConfig(ctx),
-		PprofConfig:        oppprof.ReadCLIConfig(ctx),
+		MaxPendingTransactions: ctx.GlobalUint64(flags.MaxPendingTransactionsFlag.Name),
+		MaxChannelDuration:     ctx.GlobalUint64(flags.MaxChannelDurationFlag.Name),
+		MaxL1TxSize:            ctx.GlobalUint64(flags.MaxL1TxSizeBytesFlag.Name),
+		TargetL1TxSize:         ctx.GlobalUint64(flags.TargetL1TxSizeBytesFlag.Name),
+		TargetNumFrames:        ctx.GlobalInt(flags.TargetNumFramesFlag.Name),
+		ApproxComprRatio:       ctx.GlobalFloat64(flags.ApproxComprRatioFlag.Name),
+		Stopped:                ctx.GlobalBool(flags.StoppedFlag.Name),
+		TxMgrConfig:            txmgr.ReadCLIConfig(ctx),
+		RPCConfig:              rpc.ReadCLIConfig(ctx),
+		LogConfig:              oplog.ReadCLIConfig(ctx),
+		MetricsConfig:          opmetrics.ReadCLIConfig(ctx),
+		PprofConfig:            oppprof.ReadCLIConfig(ctx),
 	}
 }

op-batcher/batcher/driver.go

@@ -75,13 +75,14 @@ func NewBatchSubmitterFromCLIConfig(cfg CLIConfig, l log.Logger, m metrics.Metri
 	}
 
 	batcherCfg := Config{
-		L1Client:       l1Client,
-		L2Client:       l2Client,
-		RollupNode:     rollupClient,
-		PollInterval:   cfg.PollInterval,
-		NetworkTimeout: cfg.TxMgrConfig.NetworkTimeout,
-		TxManager:      txManager,
-		Rollup:         rcfg,
+		L1Client:               l1Client,
+		L2Client:               l2Client,
+		RollupNode:             rollupClient,
+		PollInterval:           cfg.PollInterval,
+		MaxPendingTransactions: cfg.MaxPendingTransactions,
+		NetworkTimeout:         cfg.TxMgrConfig.NetworkTimeout,
+		TxManager:              txManager,
+		Rollup:                 rcfg,
 		Channel: ChannelConfig{
 			SeqWindowSize:      rcfg.SeqWindowSize,
 			ChannelTimeout:     rcfg.ChannelTimeout,
@@ -286,13 +287,23 @@ func (l *BatchSubmitter) loop() {
 
 	ticker := time.NewTicker(l.PollInterval)
 	defer ticker.Stop()
+
+	receiptsCh := make(chan txmgr.TxReceipt[txData])
+	queue := txmgr.NewQueue[txData](l.killCtx, l.txMgr, l.MaxPendingTransactions)
+
 	for {
 		select {
 		case <-ticker.C:
 			l.loadBlocksIntoState(l.shutdownCtx)
-			l.publishStateToL1(l.killCtx)
+			l.publishStateToL1(queue, receiptsCh, false)
+		case r := <-receiptsCh:
+			l.handleReceipt(r)
 		case <-l.shutdownCtx.Done():
-			l.publishStateToL1(l.killCtx)
+			err := l.state.Close()
+			if err != nil {
+				l.log.Error("error closing the channel manager", "err", err)
+			}
+			l.publishStateToL1(queue, receiptsCh, true)
 			return
 		}
 	}
@@ -300,70 +311,90 @@ func (l *BatchSubmitter) loop() {
 
 // publishStateToL1 loops through the block data loaded into `state` and
 // submits the associated data to the L1 in the form of channel frames.
-func (l *BatchSubmitter) publishStateToL1(ctx context.Context) {
-	for {
-		// Attempt to gracefully terminate the current channel, ensuring that no new frames will be
-		// produced. Any remaining frames must still be published to the L1 to prevent stalling.
-		select {
-		case <-ctx.Done():
-			err := l.state.Close()
-			if err != nil {
-				l.log.Error("error closing the channel manager", "err", err)
+func (l *BatchSubmitter) publishStateToL1(queue *txmgr.Queue[txData], receiptsCh chan txmgr.TxReceipt[txData], drain bool) {
+	txDone := make(chan struct{})
+	// send/wait and receipt reading must be on a separate goroutines to avoid deadlocks
+	go func() {
+		defer func() {
+			if drain {
+				// if draining, we wait for all transactions to complete
+				queue.Wait()
 			}
-		case <-l.shutdownCtx.Done():
-			err := l.state.Close()
+			close(txDone)
+		}()
+		for {
+			err := l.publishTxToL1(l.killCtx, queue, receiptsCh)
 			if err != nil {
-				l.log.Error("error closing the channel manager", "err", err)
+				if drain && err != io.EOF {
+					l.log.Error("error sending tx while draining state", "err", err)
+				}
+				return
 			}
-		default:
 		}
+	}()
 
-		l1tip, err := l.l1Tip(ctx)
-		if err != nil {
-			l.log.Error("Failed to query L1 tip", "error", err)
+	for {
+		select {
+		case r := <-receiptsCh:
+			l.handleReceipt(r)
+		case <-txDone:
 			return
 		}
-		l.recordL1Tip(l1tip)
+	}
+}
 
-		// Collect next transaction data
-		txdata, err := l.state.TxData(l1tip.ID())
-		if err == io.EOF {
-			l.log.Trace("no transaction data available")
-			break
-		} else if err != nil {
-			l.log.Error("unable to get tx data", "err", err)
-			break
-		}
-		// Record TX Status
-		if receipt, err := l.sendTransaction(ctx, txdata.Bytes()); err != nil {
-			l.recordFailedTx(txdata.ID(), err)
-		} else {
-			l.recordConfirmedTx(txdata.ID(), receipt)
-		}
+// publishTxToL1 submits a single state tx to the L1
+func (l *BatchSubmitter) publishTxToL1(ctx context.Context, queue *txmgr.Queue[txData], receiptsCh chan txmgr.TxReceipt[txData]) error {
+	// send all available transactions
+	l1tip, err := l.l1Tip(ctx)
+	if err != nil {
+		l.log.Error("Failed to query L1 tip", "error", err)
+		return err
 	}
+	l.recordL1Tip(l1tip)
+
+	// Collect next transaction data
+	txdata, err := l.state.TxData(l1tip.ID())
+	if err == io.EOF {
+		l.log.Trace("no transaction data available")
+		return err
+	} else if err != nil {
+		l.log.Error("unable to get tx data", "err", err)
+		return err
+	}
+
+	l.sendTransaction(txdata, queue, receiptsCh)
+	return nil
 }
 
 // sendTransaction creates & submits a transaction to the batch inbox address with the given `data`.
 // It currently uses the underlying `txmgr` to handle transaction sending & price management.
 // This is a blocking method. It should not be called concurrently.
-func (l *BatchSubmitter) sendTransaction(ctx context.Context, data []byte) (*types.Receipt, error) {
+func (l *BatchSubmitter) sendTransaction(txdata txData, queue *txmgr.Queue[txData], receiptsCh chan txmgr.TxReceipt[txData]) {
 	// Do the gas estimation offline. A value of 0 will cause the [txmgr] to estimate the gas limit.
+	data := txdata.Bytes()
 	intrinsicGas, err := core.IntrinsicGas(data, nil, false, true, true, false)
 	if err != nil {
-		return nil, fmt.Errorf("failed to calculate intrinsic gas: %w", err)
+		l.log.Error("Failed to calculate intrinsic gas", "error", err)
+		return
 	}
 
-	// Send the transaction through the txmgr
-	if receipt, err := l.txMgr.Send(ctx, txmgr.TxCandidate{
+	candidate := txmgr.TxCandidate{
 		To:       &l.Rollup.BatchInboxAddress,
 		TxData:   data,
 		GasLimit: intrinsicGas,
-	}); err != nil {
-		l.log.Warn("unable to publish tx", "err", err, "data_size", len(data))
-		return nil, err
+	}
+	queue.Send(txdata, candidate, receiptsCh)
+}
+
+func (l *BatchSubmitter) handleReceipt(r txmgr.TxReceipt[txData]) {
+	// Record TX Status
+	if r.Err != nil {
+		l.log.Warn("unable to publish tx", "err", r.Err, "data_size", r.ID.Len())
+		l.recordFailedTx(r.ID.ID(), r.Err)
 	} else {
-		l.log.Info("tx successfully published", "tx_hash", receipt.TxHash, "data_size", len(data))
-		return receipt, nil
+		l.log.Info("tx successfully published", "tx_hash", r.Receipt.TxHash, "data_size", r.ID.Len())
+		l.recordConfirmedTx(r.ID.ID(), r.Receipt)
 	}
 }
 

op-batcher/batcher/tx_data.go

@@ -26,6 +26,10 @@ func (td *txData) Bytes() []byte {
 	return append([]byte{derive.DerivationVersion0}, td.frame.data...)
 }
 
+func (td *txData) Len() int {
+	return 1 + len(td.frame.data)
+}
+
 // Frame returns the single frame of this tx data.
 //
 // Note: when the batcher is changed to possibly send multiple frames per tx,

op-batcher/flags/flags.go

@@ -2,6 +2,7 @@ package flags
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/urfave/cli"
 
@@ -33,21 +34,27 @@ var (
 		Usage:  "HTTP provider URL for Rollup node",
 		EnvVar: opservice.PrefixEnvVar(envVarPrefix, "ROLLUP_RPC"),
 	}
+	// Optional flags
 	SubSafetyMarginFlag = cli.Uint64Flag{
 		Name: "sub-safety-margin",
 		Usage: "The batcher tx submission safety margin (in #L1-blocks) to subtract " +
 			"from a channel's timeout and sequencing window, to guarantee safe inclusion " +
 			"of a channel on L1.",
+		Value:  10,
 		EnvVar: opservice.PrefixEnvVar(envVarPrefix, "SUB_SAFETY_MARGIN"),
 	}
 	PollIntervalFlag = cli.DurationFlag{
-		Name: "poll-interval",
-		Usage: "Delay between querying L2 for more transactions and " +
-			"creating a new batch",
+		Name:   "poll-interval",
+		Usage:  "How frequently to poll L2 for new blocks",
+		Value:  6 * time.Second,
 		EnvVar: opservice.PrefixEnvVar(envVarPrefix, "POLL_INTERVAL"),
 	}
-
-	// Optional flags
+	MaxPendingTransactionsFlag = cli.Uint64Flag{
+		Name:   "max-pending-tx",
+		Usage:  "The maximum number of pending transactions. 0 for no limit.",
+		Value:  1,
+		EnvVar: opservice.PrefixEnvVar(envVarPrefix, "MAX_PENDING_TX"),
+	}
 	MaxChannelDurationFlag = cli.Uint64Flag{
 		Name:   "max-channel-duration",
 		Usage:  "The maximum duration of L1-blocks to keep a channel open. 0 to disable.",
@@ -91,11 +98,12 @@ var requiredFlags = []cli.Flag{
 	L1EthRpcFlag,
 	L2EthRpcFlag,
 	RollupRpcFlag,
-	SubSafetyMarginFlag,
-	PollIntervalFlag,
 }
 
 var optionalFlags = []cli.Flag{
+	SubSafetyMarginFlag,
+	PollIntervalFlag,
+	MaxPendingTransactionsFlag,
 	MaxChannelDurationFlag,
 	MaxL1TxSizeBytesFlag,
 	TargetL1TxSizeBytesFlag,

op-chain-ops/cmd/withdrawals/main.go

@@ -19,6 +19,7 @@ import (
 	"github.com/ethereum-optimism/optimism/op-chain-ops/crossdomain"
 	"github.com/ethereum-optimism/optimism/op-chain-ops/genesis"
 	"github.com/ethereum-optimism/optimism/op-chain-ops/util"
+	"github.com/ethereum-optimism/optimism/op-node/rollup"
 	"github.com/ethereum/go-ethereum/accounts/abi/bind"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
@@ -933,14 +934,12 @@ func createOutput(
 		LatestBlockhash:          header.Hash(),
 	}
 
-	// TODO(mark): import the function from `op-node` to compute the hash
-	// instead of doing this. Will update when testing against mainnet.
-	localOutputRootHash := crypto.Keccak256Hash(
-		outputRootProof.Version[:],
-		outputRootProof.StateRoot[:],
-		outputRootProof.MessagePasserStorageRoot[:],
-		outputRootProof.LatestBlockhash[:],
-	)
+	// Compute the output root locally
+	l2OutputRoot, err := rollup.ComputeL2OutputRoot(&outputRootProof)
+	localOutputRootHash := common.Hash(l2OutputRoot)
+	if err != nil {
+		return nil, bindings.TypesOutputRootProof{}, nil, err
+	}
 
 	// ensure that the locally computed hash matches
 	if l2Output.OutputRoot != localOutputRootHash {

op-e2e/setup.go

@@ -593,17 +593,18 @@ func (cfg SystemConfig) Start(_opts ...SystemConfigOption) (*System, error) {
 
 	// Batch Submitter
 	sys.BatchSubmitter, err = bss.NewBatchSubmitterFromCLIConfig(bss.CLIConfig{
-		L1EthRpc:           sys.Nodes["l1"].WSEndpoint(),
-		L2EthRpc:           sys.Nodes["sequencer"].WSEndpoint(),
-		RollupRpc:          sys.RollupNodes["sequencer"].HTTPEndpoint(),
-		MaxChannelDuration: 1,
-		MaxL1TxSize:        120_000,
-		TargetL1TxSize:     100_000,
-		TargetNumFrames:    1,
-		ApproxComprRatio:   0.4,
-		SubSafetyMargin:    4,
-		PollInterval:       50 * time.Millisecond,
-		TxMgrConfig:        newTxMgrConfig(sys.Nodes["l1"].WSEndpoint(), cfg.Secrets.Batcher),
+		L1EthRpc:               sys.Nodes["l1"].WSEndpoint(),
+		L2EthRpc:               sys.Nodes["sequencer"].WSEndpoint(),
+		RollupRpc:              sys.RollupNodes["sequencer"].HTTPEndpoint(),
+		MaxPendingTransactions: 1,
+		MaxChannelDuration:     1,
+		MaxL1TxSize:            120_000,
+		TargetL1TxSize:         100_000,
+		TargetNumFrames:        1,
+		ApproxComprRatio:       0.4,
+		SubSafetyMargin:        4,
+		PollInterval:           50 * time.Millisecond,
+		TxMgrConfig:            newTxMgrConfig(sys.Nodes["l1"].WSEndpoint(), cfg.Secrets.Batcher),
 		LogConfig: oplog.CLIConfig{
 			Level:  "info",
 			Format: "text",

op-proposer/flags/flags.go

@@ -2,6 +2,7 @@ package flags
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/urfave/cli"
 
@@ -32,13 +33,14 @@ var (
 		Usage:  "Address of the L2OutputOracle contract",
 		EnvVar: opservice.PrefixEnvVar(envVarPrefix, "L2OO_ADDRESS"),
 	}
+
+	// Optional flags
 	PollIntervalFlag = cli.DurationFlag{
-		Name: "poll-interval",
-		Usage: "Delay between querying L2 for more transactions and " +
-			"creating a new batch",
+		Name:   "poll-interval",
+		Usage:  "How frequently to poll L2 for new blocks",
+		Value:  6 * time.Second,
 		EnvVar: opservice.PrefixEnvVar(envVarPrefix, "POLL_INTERVAL"),
 	}
-	// Optional flags
 	AllowNonFinalizedFlag = cli.BoolFlag{
 		Name:   "allow-non-finalized",
 		Usage:  "Allow the proposer to submit proposals for L2 blocks derived from non-finalized L1 blocks.",
@@ -52,10 +54,10 @@ var requiredFlags = []cli.Flag{
 	L1EthRpcFlag,
 	RollupRpcFlag,
 	L2OOAddressFlag,
-	PollIntervalFlag,
 }
 
 var optionalFlags = []cli.Flag{
+	PollIntervalFlag,
 	AllowNonFinalizedFlag,
 }
 

op-service/txmgr/metrics/noop.go

@@ -5,6 +5,7 @@ import "github.com/ethereum/go-ethereum/core/types"
 type NoopTxMetrics struct{}
 
 func (*NoopTxMetrics) RecordNonce(uint64)                {}
+func (*NoopTxMetrics) RecordPendingTx(int64)             {}
 func (*NoopTxMetrics) RecordGasBumpCount(int)            {}
 func (*NoopTxMetrics) RecordTxConfirmationLatency(int64) {}
 func (*NoopTxMetrics) TxConfirmed(*types.Receipt)        {}

op-service/txmgr/metrics/tx_metrics.go

@@ -12,6 +12,7 @@ type TxMetricer interface {
 	RecordGasBumpCount(int)
 	RecordTxConfirmationLatency(int64)
 	RecordNonce(uint64)
+	RecordPendingTx(pending int64)
 	TxConfirmed(*types.Receipt)
 	TxPublished(string)
 	RPCError()
@@ -24,6 +25,7 @@ type TxMetrics struct {
 	txFeeHistogram     prometheus.Histogram
 	LatencyConfirmedTx prometheus.Gauge
 	currentNonce       prometheus.Gauge
+	pendingTxs         prometheus.Gauge
 	txPublishError     *prometheus.CounterVec
 	publishEvent       metrics.Event
 	confirmEvent       metrics.EventVec
@@ -82,6 +84,12 @@ func MakeTxMetrics(ns string, factory metrics.Factory) TxMetrics {
 			Help:      "Current nonce of the from address",
 			Subsystem: "txmgr",
 		}),
+		pendingTxs: factory.NewGauge(prometheus.GaugeOpts{
+			Namespace: ns,
+			Name:      "pending_txs",
+			Help:      "Number of transactions pending receipts",
+			Subsystem: "txmgr",
+		}),
 		txPublishError: factory.NewCounterVec(prometheus.CounterOpts{
 			Namespace: ns,
 			Name:      "tx_publish_error_count",
@@ -103,6 +111,10 @@ func (t *TxMetrics) RecordNonce(nonce uint64) {
 	t.currentNonce.Set(float64(nonce))
 }
 
+func (t *TxMetrics) RecordPendingTx(pending int64) {
+	t.pendingTxs.Set(float64(pending))
+}
+
 // TxConfirmed records lots of information about the confirmed transaction
 func (t *TxMetrics) TxConfirmed(receipt *types.Receipt) {
 	fee := float64(receipt.EffectiveGasPrice.Uint64() * receipt.GasUsed / params.GWei)

op-service/txmgr/queue.go

+package txmgr
+
+import (
+	"context"
+	"math"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"golang.org/x/sync/errgroup"
+)
+
+type TxReceipt[T any] struct {
+	// ID can be used to identify unique tx receipts within the recept channel
+	ID T
+	// Receipt result from the transaction send
+	Receipt *types.Receipt
+	// Err contains any error that occurred during the tx send
+	Err error
+}
+
+type Queue[T any] struct {
+	ctx        context.Context
+	txMgr      TxManager
+	maxPending uint64
+	groupLock  sync.Mutex
+	groupCtx   context.Context
+	group      *errgroup.Group
+}
+
+// NewQueue creates a new transaction sending Queue, with the following parameters:
+//   - maxPending: max number of pending txs at once (0 == no limit)
+//   - pendingChanged: called whenever a tx send starts or finishes. The
+//     number of currently pending txs is passed as a parameter.
+func NewQueue[T any](ctx context.Context, txMgr TxManager, maxPending uint64) *Queue[T] {
+	if maxPending > math.MaxInt {
+		// ensure we don't overflow as errgroup only accepts int; in reality this will never be an issue
+		maxPending = math.MaxInt
+	}
+	return &Queue[T]{
+		ctx:        ctx,
+		txMgr:      txMgr,
+		maxPending: maxPending,
+	}
+}
+
+// Wait waits for all pending txs to complete (or fail).
+func (q *Queue[T]) Wait() {
+	if q.group == nil {
+		return
+	}
+	_ = q.group.Wait()
+}
+
+// Send will wait until the number of pending txs is below the max pending,
+// and then send the next tx.
+//
+// The actual tx sending is non-blocking, with the receipt returned on the
+// provided receipt channel. If the channel is unbuffered, the goroutine is
+// blocked from completing until the channel is read from.
+func (q *Queue[T]) Send(id T, candidate TxCandidate, receiptCh chan TxReceipt[T]) {
+	group, ctx := q.groupContext()
+	group.Go(func() error {
+		return q.sendTx(ctx, id, candidate, receiptCh)
+	})
+}
+
+// TrySend sends the next tx, but only if the number of pending txs is below the
+// max pending.
+//
+// Returns false if there is no room in the queue to send. Otherwise, the
+// transaction is queued and this method returns true.
+//
+// The actual tx sending is non-blocking, with the receipt returned on the
+// provided receipt channel. If the channel is unbuffered, the goroutine is
+// blocked from completing until the channel is read from.
+func (q *Queue[T]) TrySend(id T, candidate TxCandidate, receiptCh chan TxReceipt[T]) bool {
+	group, ctx := q.groupContext()
+	return group.TryGo(func() error {
+		return q.sendTx(ctx, id, candidate, receiptCh)
+	})
+}
+
+func (q *Queue[T]) sendTx(ctx context.Context, id T, candidate TxCandidate, receiptCh chan TxReceipt[T]) error {
+	receipt, err := q.txMgr.Send(ctx, candidate)
+	receiptCh <- TxReceipt[T]{
+		ID:      id,
+		Receipt: receipt,
+		Err:     err,
+	}
+	return err
+}
+
+// groupContext returns a Group and a Context to use when sending a tx.
+//
+// If any of the pending transactions returned an error, the queue's shared error Group is
+// canceled. This method will wait on that Group for all pending transactions to return,
+// and create a new Group with the queue's global context as its parent.
+func (q *Queue[T]) groupContext() (*errgroup.Group, context.Context) {
+	q.groupLock.Lock()
+	defer q.groupLock.Unlock()
+	if q.groupCtx == nil || q.groupCtx.Err() != nil {
+		// no group exists, or the existing context has an error, so we need to wait
+		// for existing group threads to complete (if any) and create a new group
+		if q.group != nil {
+			_ = q.group.Wait()
+		}
+		q.group, q.groupCtx = errgroup.WithContext(q.ctx)
+		if q.maxPending > 0 {
+			q.group.SetLimit(int(q.maxPending))
+		}
+	}
+	return q.group, q.groupCtx
+}

op-service/txmgr/queue_test.go

+package txmgr
+
+import (
+	"context"
+	"fmt"
+	"math/big"
+	"testing"
+	"time"
+
+	"github.com/ethereum-optimism/optimism/op-node/testlog"
+	"github.com/ethereum-optimism/optimism/op-service/txmgr/metrics"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/exp/slices"
+)
+
+type queueFunc func(id int, candidate TxCandidate, receiptCh chan TxReceipt[int], q *Queue[int]) bool
+
+func sendQueueFunc(id int, candidate TxCandidate, receiptCh chan TxReceipt[int], q *Queue[int]) bool {
+	q.Send(id, candidate, receiptCh)
+	return true
+}
+
+func trySendQueueFunc(id int, candidate TxCandidate, receiptCh chan TxReceipt[int], q *Queue[int]) bool {
+	return q.TrySend(id, candidate, receiptCh)
+}
+
+type queueCall struct {
+	call   queueFunc // queue call (either Send or TrySend, use function helpers above)
+	queued bool      // true if the send was queued
+	txErr  bool      // true if the tx send should return an error
+}
+
+type testTx struct {
+	sendErr bool // error to return from send for this tx
+}
+
+type testCase struct {
+	name   string        // name of the test
+	max    uint64        // max concurrency of the queue
+	calls  []queueCall   // calls to the queue
+	txs    []testTx      // txs to generate from the factory (and potentially error in send)
+	nonces []uint64      // expected sent tx nonces after all calls are made
+	total  time.Duration // approx. total time it should take to complete all queue calls
+}
+
+type mockBackendWithNonce struct {
+	mockBackend
+}
+
+func newMockBackendWithNonce(g *gasPricer) *mockBackendWithNonce {
+	return &mockBackendWithNonce{
+		mockBackend: mockBackend{
+			g:        g,
+			minedTxs: make(map[common.Hash]minedTxInfo),
+		},
+	}
+}
+
+func (b *mockBackendWithNonce) NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error) {
+	return uint64(len(b.minedTxs)), nil
+}
+
+func TestSend(t *testing.T) {
+	testCases := []testCase{
+		{
+			name: "success",
+			max:  5,
+			calls: []queueCall{
+				{call: trySendQueueFunc, queued: true},
+				{call: trySendQueueFunc, queued: true},
+			},
+			txs: []testTx{
+				{},
+				{},
+			},
+			nonces: []uint64{0, 1},
+			total:  1 * time.Second,
+		},
+		{
+			name: "no limit",
+			max:  0,
+			calls: []queueCall{
+				{call: trySendQueueFunc, queued: true},
+				{call: trySendQueueFunc, queued: true},
+			},
+			txs: []testTx{
+				{},
+				{},
+			},
+			nonces: []uint64{0, 1},
+			total:  1 * time.Second,
+		},
+		{
+			name: "single threaded",
+			max:  1,
+			calls: []queueCall{
+				{call: trySendQueueFunc, queued: true},
+				{call: trySendQueueFunc, queued: false},
+				{call: trySendQueueFunc, queued: false},
+			},
+			txs: []testTx{
+				{},
+			},
+			nonces: []uint64{0},
+			total:  1 * time.Second,
+		},
+		{
+			name: "single threaded blocking",
+			max:  1,
+			calls: []queueCall{
+				{call: trySendQueueFunc, queued: true},
+				{call: trySendQueueFunc, queued: false},
+				{call: sendQueueFunc, queued: true},
+				{call: sendQueueFunc, queued: true},
+			},
+			txs: []testTx{
+				{},
+				{},
+				{},
+			},
+			nonces: []uint64{0, 1, 2},
+			total:  3 * time.Second,
+		},
+		{
+			name: "dual threaded blocking",
+			max:  2,
+			calls: []queueCall{
+				{call: trySendQueueFunc, queued: true},
+				{call: trySendQueueFunc, queued: true},
+				{call: trySendQueueFunc, queued: false},
+				{call: sendQueueFunc, queued: true},
+				{call: sendQueueFunc, queued: true},
+				{call: sendQueueFunc, queued: true},
+			},
+			txs: []testTx{
+				{},
+				{},
+				{},
+				{},
+				{},
+			},
+			nonces: []uint64{0, 1, 2, 3, 4},
+			total:  3 * time.Second,
+		},
+		{
+			name: "subsequent txs fail after tx failure",
+			max:  1,
+			calls: []queueCall{
+				{call: sendQueueFunc, queued: true},
+				{call: sendQueueFunc, queued: true, txErr: true},
+				{call: sendQueueFunc, queued: true, txErr: true},
+			},
+			txs: []testTx{
+				{},
+				{sendErr: true},
+				{},
+			},
+			nonces: []uint64{0, 1, 1},
+			total:  3 * time.Second,
+		},
+	}
+	for _, test := range testCases {
+		test := test
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			conf := configWithNumConfs(1)
+			conf.ReceiptQueryInterval = 1 * time.Second // simulate a network send
+			conf.ResubmissionTimeout = 2 * time.Second  // resubmit to detect errors
+			conf.SafeAbortNonceTooLowCount = 1
+			backend := newMockBackendWithNonce(newGasPricer(3))
+			mgr := &SimpleTxManager{
+				chainID: conf.ChainID,
+				name:    "TEST",
+				cfg:     conf,
+				backend: backend,
+				l:       testlog.Logger(t, log.LvlCrit),
+				metr:    &metrics.NoopTxMetrics{},
+			}
+
+			// track the nonces, and return any expected errors from tx sending
+			var nonces []uint64
+			sendTx := func(ctx context.Context, tx *types.Transaction) error {
+				index := int(tx.Data()[0])
+				nonces = append(nonces, tx.Nonce())
+				var testTx *testTx
+				if index < len(test.txs) {
+					testTx = &test.txs[index]
+				}
+				if testTx != nil && testTx.sendErr {
+					return core.ErrNonceTooLow
+				}
+				txHash := tx.Hash()
+				backend.mine(&txHash, tx.GasFeeCap())
+				return nil
+			}
+			backend.setTxSender(sendTx)
+
+			ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
+			defer cancel()
+			queue := NewQueue[int](ctx, mgr, test.max)
+
+			// make all the queue calls given in the test case
+			start := time.Now()
+			for i, c := range test.calls {
+				msg := fmt.Sprintf("Call %d", i)
+				c := c
+				receiptCh := make(chan TxReceipt[int], 1)
+				candidate := TxCandidate{
+					TxData: []byte{byte(i)},
+					To:     &common.Address{},
+				}
+				queued := c.call(i, candidate, receiptCh, queue)
+				require.Equal(t, c.queued, queued, msg)
+				go func() {
+					r := <-receiptCh
+					if c.txErr {
+						require.Error(t, r.Err, msg)
+					} else {
+						require.NoError(t, r.Err, msg)
+					}
+				}()
+			}
+			// wait for the queue to drain (all txs complete or failed)
+			queue.Wait()
+			duration := time.Since(start)
+			// expect the execution time within a certain window
+			now := time.Now()
+			require.WithinDuration(t, now.Add(test.total), now.Add(duration), 500*time.Millisecond, "unexpected queue transaction timing")
+			// check that the nonces match
+			slices.Sort(nonces)
+			require.Equal(t, test.nonces, nonces, "expected nonces do not match")
+		})
+	}
+}

op-service/txmgr/txmgr.go

@@ -4,10 +4,10 @@ import (
 	"context"
 	"errors"
 	"fmt"
-
 	"math/big"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum"
@@ -38,7 +38,7 @@ type TxManager interface {
 	// It can be stopped by cancelling the provided context; however, the transaction
 	// may be included on L1 even if the context is cancelled.
 	//
-	// NOTE: Send should be called by AT MOST one caller at a time.
+	// NOTE: Send can be called concurrently, the nonce will be managed internally.
 	Send(ctx context.Context, candidate TxCandidate) (*types.Receipt, error)
 
 	// From returns the sending address associated with the instance of the transaction manager.
@@ -84,6 +84,11 @@ type SimpleTxManager struct {
 	backend ETHBackend
 	l       log.Logger
 	metr    metrics.TxMetricer
+
+	nonce     *uint64
+	nonceLock sync.RWMutex
+
+	pending atomic.Int64
 }
 
 // NewSimpleTxManager initializes a new SimpleTxManager with the passed Config.
@@ -126,8 +131,21 @@ type TxCandidate struct {
 // The transaction manager handles all signing. If and only if the gas limit is 0, the
 // transaction manager will do a gas estimation.
 //
-// NOTE: Send should be called by AT MOST one caller at a time.
+// NOTE: Send can be called concurrently, the nonce will be managed internally.
 func (m *SimpleTxManager) Send(ctx context.Context, candidate TxCandidate) (*types.Receipt, error) {
+	m.metr.RecordPendingTx(m.pending.Add(1))
+	defer func() {
+		m.metr.RecordPendingTx(m.pending.Add(-1))
+	}()
+	receipt, err := m.send(ctx, candidate)
+	if err != nil {
+		m.resetNonce()
+	}
+	return receipt, err
+}
+
+// send performs the actual transaction creation and sending.
+func (m *SimpleTxManager) send(ctx context.Context, candidate TxCandidate) (*types.Receipt, error) {
 	if m.cfg.TxSendTimeout != 0 {
 		var cancel context.CancelFunc
 		ctx, cancel = context.WithTimeout(ctx, m.cfg.TxSendTimeout)
@@ -137,7 +155,7 @@ func (m *SimpleTxManager) Send(ctx context.Context, candidate TxCandidate) (*typ
 	if err != nil {
 		return nil, fmt.Errorf("failed to create the tx: %w", err)
 	}
-	return m.send(ctx, tx)
+	return m.sendTx(ctx, tx)
 }
 
 // craftTx creates the signed transaction
@@ -153,15 +171,10 @@ func (m *SimpleTxManager) craftTx(ctx context.Context, candidate TxCandidate) (*
 	}
 	gasFeeCap := calcGasFeeCap(basefee, gasTipCap)
 
-	// Fetch the sender's nonce from the latest known block (nil `blockNumber`)
-	childCtx, cancel := context.WithTimeout(ctx, m.cfg.NetworkTimeout)
-	defer cancel()
-	nonce, err := m.backend.NonceAt(childCtx, m.cfg.From, nil)
+	nonce, err := m.nextNonce(ctx)
 	if err != nil {
-		m.metr.RPCError()
-		return nil, fmt.Errorf("failed to get nonce: %w", err)
+		return nil, err
 	}
-	m.metr.RecordNonce(nonce)
 
 	rawTx := &types.DynamicFeeTx{
 		ChainID:   m.chainID,
@@ -192,14 +205,48 @@ func (m *SimpleTxManager) craftTx(ctx context.Context, candidate TxCandidate) (*
 		rawTx.Gas = gas
 	}
 
-	ctx, cancel = context.WithTimeout(ctx, m.cfg.NetworkTimeout)
+	ctx, cancel := context.WithTimeout(ctx, m.cfg.NetworkTimeout)
 	defer cancel()
 	return m.cfg.Signer(ctx, m.cfg.From, types.NewTx(rawTx))
 }
 
+// nextNonce returns a nonce to use for the next transaction. It uses
+// eth_getTransactionCount with "latest" once, and then subsequent calls simply
+// increment this number. If the transaction manager is reset, it will query the
+// eth_getTransactionCount nonce again.
+func (m *SimpleTxManager) nextNonce(ctx context.Context) (uint64, error) {
+	m.nonceLock.Lock()
+	defer m.nonceLock.Unlock()
+
+	if m.nonce == nil {
+		// Fetch the sender's nonce from the latest known block (nil `blockNumber`)
+		childCtx, cancel := context.WithTimeout(ctx, m.cfg.NetworkTimeout)
+		defer cancel()
+		nonce, err := m.backend.NonceAt(childCtx, m.cfg.From, nil)
+		if err != nil {
+			m.metr.RPCError()
+			return 0, fmt.Errorf("failed to get nonce: %w", err)
+		}
+		m.nonce = &nonce
+	} else {
+		*m.nonce++
+	}
+
+	m.metr.RecordNonce(*m.nonce)
+	return *m.nonce, nil
+}
+
+// resetNonce resets the internal nonce tracking. This is called if any pending send
+// returns an error.
+func (m *SimpleTxManager) resetNonce() {
+	m.nonceLock.Lock()
+	defer m.nonceLock.Unlock()
+	m.nonce = nil
+}
+
 // send submits the same transaction several times with increasing gas prices as necessary.
 // It waits for the transaction to be confirmed on chain.
-func (m *SimpleTxManager) send(ctx context.Context, tx *types.Transaction) (*types.Receipt, error) {
+func (m *SimpleTxManager) sendTx(ctx context.Context, tx *types.Transaction) (*types.Receipt, error) {
 	var wg sync.WaitGroup
 	defer wg.Wait()
 	ctx, cancel := context.WithCancel(ctx)

op-service/txmgr/txmgr_test.go

@@ -277,7 +277,7 @@ func TestTxMgrConfirmAtMinGasPrice(t *testing.T) {
 
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
-	receipt, err := h.mgr.send(ctx, tx)
+	receipt, err := h.mgr.sendTx(ctx, tx)
 	require.Nil(t, err)
 	require.NotNil(t, receipt)
 	require.Equal(t, gasPricer.expGasFeeCap().Uint64(), receipt.GasUsed)
@@ -305,7 +305,7 @@ func TestTxMgrNeverConfirmCancel(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
-	receipt, err := h.mgr.send(ctx, tx)
+	receipt, err := h.mgr.sendTx(ctx, tx)
 	require.Equal(t, err, context.DeadlineExceeded)
 	require.Nil(t, receipt)
 }
@@ -334,7 +334,7 @@ func TestTxMgrConfirmsAtHigherGasPrice(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
-	receipt, err := h.mgr.send(ctx, tx)
+	receipt, err := h.mgr.sendTx(ctx, tx)
 	require.Nil(t, err)
 	require.NotNil(t, receipt)
 	require.Equal(t, h.gasPricer.expGasFeeCap().Uint64(), receipt.GasUsed)
@@ -365,7 +365,7 @@ func TestTxMgrBlocksOnFailingRpcCalls(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
-	receipt, err := h.mgr.send(ctx, tx)
+	receipt, err := h.mgr.sendTx(ctx, tx)
 	require.Equal(t, err, context.DeadlineExceeded)
 	require.Nil(t, receipt)
 }
@@ -443,7 +443,7 @@ func TestTxMgrOnlyOnePublicationSucceeds(t *testing.T) {
 
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
-	receipt, err := h.mgr.send(ctx, tx)
+	receipt, err := h.mgr.sendTx(ctx, tx)
 	require.Nil(t, err)
 
 	require.NotNil(t, receipt)
@@ -478,7 +478,7 @@ func TestTxMgrConfirmsMinGasPriceAfterBumping(t *testing.T) {
 
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
-	receipt, err := h.mgr.send(ctx, tx)
+	receipt, err := h.mgr.sendTx(ctx, tx)
 	require.Nil(t, err)
 	require.NotNil(t, receipt)
 	require.Equal(t, h.gasPricer.expGasFeeCap().Uint64(), receipt.GasUsed)
@@ -523,7 +523,7 @@ func TestTxMgrDoesntAbortNonceTooLowAfterMiningTx(t *testing.T) {
 
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
-	receipt, err := h.mgr.send(ctx, tx)
+	receipt, err := h.mgr.sendTx(ctx, tx)
 	require.Nil(t, err)
 	require.NotNil(t, receipt)
 	require.Equal(t, h.gasPricer.expGasFeeCap().Uint64(), receipt.GasUsed)
@@ -870,3 +870,40 @@ func TestErrStringMatch(t *testing.T) {
 		})
 	}
 }
+
+func TestNonceReset(t *testing.T) {
+	conf := configWithNumConfs(1)
+	conf.SafeAbortNonceTooLowCount = 1
+	h := newTestHarnessWithConfig(t, conf)
+
+	index := -1
+	var nonces []uint64
+	sendTx := func(ctx context.Context, tx *types.Transaction) error {
+		index++
+		nonces = append(nonces, tx.Nonce())
+		// fail every 3rd tx
+		if index%3 == 0 {
+			return core.ErrNonceTooLow
+		}
+		txHash := tx.Hash()
+		h.backend.mine(&txHash, tx.GasFeeCap())
+		return nil
+	}
+	h.backend.setTxSender(sendTx)
+
+	ctx := context.Background()
+	for i := 0; i < 8; i++ {
+		_, err := h.mgr.Send(ctx, TxCandidate{
+			To: &common.Address{},
+		})
+		// expect every 3rd tx to fail
+		if i%3 == 0 {
+			require.Error(t, err)
+		} else {
+			require.NoError(t, err)
+		}
+	}
+
+	// internal nonce tracking should be reset every 3rd tx
+	require.Equal(t, []uint64{0, 0, 1, 2, 0, 1, 2, 0}, nonces)
+}

proxyd/go.mod

@@ -31,6 +31,7 @@ require (
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/edsrzf/mmap-go v1.1.0 // indirect
+	github.com/emirpasic/gods v1.18.1 // indirect
 	github.com/fjl/memsize v0.0.1 // indirect
 	github.com/gballet/go-libpcsclite v0.0.0-20191108122812-4678299bea08 // indirect
 	github.com/go-ole/go-ole v1.2.6 // indirect

proxyd/go.sum

@@ -140,6 +140,8 @@ github.com/eclipse/paho.mqtt.golang v1.2.0/go.mod h1:H9keYFcgq3Qr5OUJm/JZI/i6U7j
 github.com/edsrzf/mmap-go v1.0.0/go.mod h1:YO35OhQPt3KJa3ryjFM5Bs14WD66h8eGKpfaBNrHW5M=
 github.com/edsrzf/mmap-go v1.1.0 h1:6EUwBLQ/Mcr1EYLE4Tn1VdW1A4ckqCQWZBw8Hr0kjpQ=
 github.com/edsrzf/mmap-go v1.1.0/go.mod h1:19H/e8pUPLicwkyNgOykDXkJ9F0MHE+Z52B8EIth78Q=
+github.com/emirpasic/gods v1.18.1 h1:FXtiHYKDGKCW2KzwZKx0iC0PQmdlorYgdFG9jPXJ1Bc=
+github.com/emirpasic/gods v1.18.1/go.mod h1:8tpGGwCnJ5H4r6BWwaV6OrWmMoPhUl5jm/FMNAnJvWQ=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=

proxyd/pkg/avg-sliding-window/sliding.go

+package avg_sliding_window
+
+import (
+	"time"
+
+	lm "github.com/emirpasic/gods/maps/linkedhashmap"
+)
+
+type Clock interface {
+	Now() time.Time
+}
+
+// DefaultClock provides a clock that gets current time from the system time
+type DefaultClock struct{}
+
+func NewDefaultClock() *DefaultClock {
+	return &DefaultClock{}
+}
+func (c DefaultClock) Now() time.Time {
+	return time.Now()
+}
+
+// AdjustableClock provides a static clock to easily override the system time
+type AdjustableClock struct {
+	now time.Time
+}
+
+func NewAdjustableClock(now time.Time) *AdjustableClock {
+	return &AdjustableClock{now: now}
+}
+func (c *AdjustableClock) Now() time.Time {
+	return c.now
+}
+func (c *AdjustableClock) Set(now time.Time) {
+	c.now = now
+}
+
+type bucket struct {
+	sum float64
+	qty uint
+}
+
+// AvgSlidingWindow calculates moving averages efficiently.
+// Data points are rounded to nearest bucket of size `bucketSize`,
+// and evicted when they are too old based on `windowLength`
+type AvgSlidingWindow struct {
+	bucketSize   time.Duration
+	windowLength time.Duration
+	clock        Clock
+	buckets      *lm.Map
+	qty          uint
+	sum          float64
+}
+
+type SlidingWindowOpts func(sw *AvgSlidingWindow)
+
+func NewSlidingWindow(opts ...SlidingWindowOpts) *AvgSlidingWindow {
+	sw := &AvgSlidingWindow{
+		buckets: lm.New(),
+	}
+	for _, opt := range opts {
+		opt(sw)
+	}
+	if sw.bucketSize == 0 {
+		sw.bucketSize = time.Second
+	}
+	if sw.windowLength == 0 {
+		sw.windowLength = 5 * time.Minute
+	}
+	if sw.clock == nil {
+		sw.clock = NewDefaultClock()
+	}
+	return sw
+}
+
+func WithWindowLength(windowLength time.Duration) SlidingWindowOpts {
+	return func(sw *AvgSlidingWindow) {
+		sw.windowLength = windowLength
+	}
+}
+
+func WithBucketSize(bucketSize time.Duration) SlidingWindowOpts {
+	return func(sw *AvgSlidingWindow) {
+		sw.bucketSize = bucketSize
+	}
+}
+
+func WithClock(clock Clock) SlidingWindowOpts {
+	return func(sw *AvgSlidingWindow) {
+		sw.clock = clock
+	}
+}
+
+func (sw *AvgSlidingWindow) inWindow(t time.Time) bool {
+	now := sw.clock.Now().Round(sw.bucketSize)
+	windowStart := now.Add(-sw.windowLength)
+	return windowStart.Before(t) && !t.After(now)
+}
+
+// Add inserts a new data point into the window, with value `val` with the current time
+func (sw *AvgSlidingWindow) Add(val float64) {
+	t := sw.clock.Now()
+	sw.AddWithTime(t, val)
+}
+
+// AddWithTime inserts a new data point into the window, with value `val` and time `t`
+func (sw *AvgSlidingWindow) AddWithTime(t time.Time, val float64) {
+	sw.advance()
+
+	key := t.Round(sw.bucketSize)
+	if !sw.inWindow(key) {
+		return
+	}
+
+	var b *bucket
+	current, found := sw.buckets.Get(key)
+	if !found {
+		b = &bucket{}
+	} else {
+		b = current.(*bucket)
+	}
+
+	// update bucket
+	bsum := b.sum
+	b.qty += 1
+	b.sum = bsum + val
+
+	// update window
+	wsum := sw.sum
+	sw.qty += 1
+	sw.sum = wsum - bsum + b.sum
+	sw.buckets.Put(key, b)
+}
+
+// advance evicts old data points
+func (sw *AvgSlidingWindow) advance() {
+	now := sw.clock.Now().Round(sw.bucketSize)
+	windowStart := now.Add(-sw.windowLength)
+	keys := sw.buckets.Keys()
+	for _, k := range keys {
+		if k.(time.Time).After(windowStart) {
+			break
+		}
+		val, _ := sw.buckets.Get(k)
+		b := val.(*bucket)
+		sw.buckets.Remove(k)
+		if sw.buckets.Size() > 0 {
+			sw.qty -= b.qty
+			sw.sum = sw.sum - b.sum
+		} else {
+			sw.qty = 0
+			sw.sum = 0.0
+		}
+	}
+}
+
+// Avg retrieves the current average for the sliding window
+func (sw *AvgSlidingWindow) Avg() float64 {
+	sw.advance()
+	if sw.qty == 0 {
+		return 0
+	}
+	return sw.sum / float64(sw.qty)
+}
+
+// Sum retrieves the current sum for the sliding window
+func (sw *AvgSlidingWindow) Sum() float64 {
+	sw.advance()
+	return sw.sum
+}
+
+// Count retrieves the data point count for the sliding window
+func (sw *AvgSlidingWindow) Count() uint {
+	sw.advance()
+	return sw.qty
+}