enhance: speed up streaming barrier timetick (milvus-io#38787)

issue: milvus-io#38399

- use last allocate but not last confirmed id to make barrier. 
- move the barrier logic into the timetick allocator.
- try to sync up local allocator and remote allocator when first barrier
check not pass to speed up.

Signed-off-by: chyezh <[email protected]>

internal/streamingnode/server/resource/idalloc/allocator.go

@@ -21,6 +21,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/cockroachdb/errors"
+
 	"github.com/milvus-io/milvus/internal/types"
 	"github.com/milvus-io/milvus/pkg/util/syncutil"
 )
@@ -33,7 +35,7 @@ var _ Allocator = (*allocatorImpl)(nil)
 // NewTSOAllocator creates a new allocator.
 func NewTSOAllocator(rc *syncutil.Future[types.RootCoordClient]) Allocator {
 	return &allocatorImpl{
-		mu:              sync.Mutex{},
+		cond:            syncutil.NewContextCond(&sync.Mutex{}),
 		remoteAllocator: newTSOAllocator(rc),
 		localAllocator:  newLocalAllocator(),
 	}
@@ -42,7 +44,7 @@ func NewTSOAllocator(rc *syncutil.Future[types.RootCoordClient]) Allocator {
 // NewIDAllocator creates a new allocator.
 func NewIDAllocator(rc *syncutil.Future[types.RootCoordClient]) Allocator {
 	return &allocatorImpl{
-		mu:              sync.Mutex{},
+		cond:            syncutil.NewContextCond(&sync.Mutex{}),
 		remoteAllocator: newIDAllocator(rc),
 		localAllocator:  newLocalAllocator(),
 	}
@@ -56,6 +58,9 @@ type Allocator interface {
 	// Allocate allocates a timestamp.
 	Allocate(ctx context.Context) (uint64, error)
 
+	// BarrierUtil make a barrier, next allocate call will generate id greater than barrier.
+	BarrierUntil(ctx context.Context, barrier uint64) error
+
 	// Sync expire the local allocator messages,
 	// syncs the local allocator and remote allocator.
 	Sync()
@@ -65,37 +70,92 @@ type Allocator interface {
 }
 
 type allocatorImpl struct {
-	mu              sync.Mutex
+	cond            *syncutil.ContextCond
 	remoteAllocator remoteBatchAllocator
 	lastSyncTime    time.Time
+	lastAllocated   uint64
 	localAllocator  *localAllocator
 }
 
-// AllocateOne allocates a timestamp.
 func (ta *allocatorImpl) Allocate(ctx context.Context) (uint64, error) {
-	ta.mu.Lock()
-	defer ta.mu.Unlock()
+	ta.cond.L.Lock()
+	defer ta.cond.L.Unlock()
+
+	return ta.allocateOne(ctx)
+}
+
+func (ta *allocatorImpl) BarrierUntil(ctx context.Context, barrier uint64) error {
+	err := ta.barrierFastPath(ctx, barrier)
+	if err == nil {
+		return nil
+	}
+	if !errors.Is(err, errFastPathFailed) {
+		return err
+	}
+
+	// Fall back to the slow path to avoid block other id allocation opeartions.
+	ta.cond.L.Lock()
+	for ta.lastAllocated < barrier {
+		if err := ta.cond.Wait(ctx); err != nil {
+			return err
+		}
+	}
+	ta.cond.L.Unlock()
+	return nil
+}
+
+func (ta *allocatorImpl) barrierFastPath(ctx context.Context, barrier uint64) error {
+	ta.cond.L.Lock()
+	defer ta.cond.L.Unlock()
+
+	for i := 0; i < 2; i++ {
+		id, err := ta.allocateOne(ctx)
+		if err != nil {
+			return err
+		}
+
+		// check if the allocated id is greater than barrier.
+		if id >= barrier {
+			return nil
+		}
+		if i == 0 {
+			// force to syncup the local allocator and remote allocator at first time.
+			// It's the fast path if the barrier is allocated from same remote allocator.
+			ta.localAllocator.exhausted()
+		}
+	}
+	return errFastPathFailed
+}
 
+func (ta *allocatorImpl) allocateOne(ctx context.Context) (uint64, error) {
 	// allocate one from local allocator first.
 	if id, err := ta.localAllocator.allocateOne(); err == nil {
+		ta.lastAllocated = id
+		ta.cond.UnsafeBroadcast()
 		return id, nil
 	}
 	// allocate from remote.
-	return ta.allocateRemote(ctx)
+	id, err := ta.allocateRemote(ctx)
+	if err != nil {
+		return 0, err
+	}
+	ta.lastAllocated = id
+	ta.cond.UnsafeBroadcast()
+	return id, nil
 }
 
 // Sync expire the local allocator messages,
 // syncs the local allocator and remote allocator.
 func (ta *allocatorImpl) Sync() {
-	ta.mu.Lock()
-	defer ta.mu.Unlock()
+	ta.cond.L.Lock()
+	defer ta.cond.L.Unlock()
 
 	ta.localAllocator.exhausted()
 }
 
 func (ta *allocatorImpl) SyncIfExpired(expire time.Duration) {
-	ta.mu.Lock()
-	defer ta.mu.Unlock()
+	ta.cond.L.Lock()
+	defer ta.cond.L.Unlock()
 
 	if time.Since(ta.lastSyncTime) > expire {
 		ta.localAllocator.exhausted()

internal/streamingnode/server/resource/idalloc/allocator_test.go

@@ -58,3 +58,52 @@ func TestTimestampAllocator(t *testing.T) {
 	_, err := allocator.Allocate(context.Background())
 	assert.Error(t, err)
 }
+
+func TestIDAllocator(t *testing.T) {
+	paramtable.Init()
+	paramtable.SetNodeID(1)
+
+	client := NewMockRootCoordClient(t)
+	f := syncutil.NewFuture[types.RootCoordClient]()
+	f.Set(client)
+
+	allocator := NewIDAllocator(f)
+
+	// Make local dirty
+	allocator.Allocate(context.Background())
+	// Test barrier fast path.
+	resp, err := client.AllocID(context.Background(), &rootcoordpb.AllocIDRequest{
+		Count: 100,
+	})
+	assert.NoError(t, err)
+	err = allocator.BarrierUntil(context.Background(), uint64(resp.ID))
+	assert.NoError(t, err)
+	newBarrierTimeTick, err := allocator.Allocate(context.Background())
+	assert.NoError(t, err)
+	assert.Greater(t, newBarrierTimeTick, uint64(resp.ID))
+
+	// Test slow path.
+	ch := make(chan struct{})
+	go func() {
+		barrier := newBarrierTimeTick + 1*batchAllocateSize
+		err := allocator.BarrierUntil(context.Background(), barrier)
+		assert.NoError(t, err)
+		newBarrierTimeTick, err := allocator.Allocate(context.Background())
+		assert.NoError(t, err)
+		assert.Greater(t, newBarrierTimeTick, barrier)
+		close(ch)
+	}()
+	select {
+	case <-ch:
+		assert.Fail(t, "should not finish")
+	case <-time.After(time.Millisecond * 20):
+	}
+	allocator.Sync()
+	_, err = allocator.Allocate(context.Background())
+	assert.NoError(t, err)
+	<-ch
+
+	allocator.SyncIfExpired(time.Millisecond * 50)
+	time.Sleep(time.Millisecond * 10)
+	allocator.SyncIfExpired(time.Millisecond * 10)
+}

internal/streamingnode/server/resource/idalloc/basic_allocator.go

@@ -15,7 +15,10 @@ import (
 	"github.com/milvus-io/milvus/pkg/util/syncutil"
 )
 
-var errExhausted = errors.New("exhausted")
+var (
+	errExhausted      = errors.New("exhausted")
+	errFastPathFailed = errors.New("fast path failed")
+)
 
 // newLocalAllocator creates a new local allocator.
 func newLocalAllocator() *localAllocator {

internal/streamingnode/server/wal/interceptors/timetick/ack/manager.go

@@ -8,13 +8,12 @@ import (
 	"github.com/milvus-io/milvus/internal/streamingnode/server/resource"
 	"github.com/milvus-io/milvus/internal/streamingnode/server/wal/metricsutil"
 	"github.com/milvus-io/milvus/pkg/streaming/util/message"
-	"github.com/milvus-io/milvus/pkg/util/syncutil"
 	"github.com/milvus-io/milvus/pkg/util/typeutil"
 )
 
 // AckManager manages the timestampAck.
 type AckManager struct {
-	cond                  *syncutil.ContextCond
+	mu                    sync.Mutex
 	lastAllocatedTimeTick uint64                // The last allocated time tick, the latest timestamp allocated by the allocator.
 	lastConfirmedTimeTick uint64                // The last confirmed time tick, the message which time tick less than lastConfirmedTimeTick has been committed into wal.
 	notAckHeap            typeutil.Heap[*Acker] // A minimum heap of timestampAck to search minimum allocated but not ack timestamp in list.
@@ -34,7 +33,7 @@ func NewAckManager(
 	metrics *metricsutil.TimeTickMetrics,
 ) *AckManager {
 	return &AckManager{
-		cond:                  syncutil.NewContextCond(&sync.Mutex{}),
+		mu:                    sync.Mutex{},
 		lastAllocatedTimeTick: 0,
 		notAckHeap:            typeutil.NewHeap[*Acker](&ackersOrderByTimestamp{}),
 		ackHeap:               typeutil.NewHeap[*Acker](&ackersOrderByEndTimestamp{}),
@@ -46,23 +45,18 @@ func NewAckManager(
 
 // AllocateWithBarrier allocates a timestamp with a barrier.
 func (ta *AckManager) AllocateWithBarrier(ctx context.Context, barrierTimeTick uint64) (*Acker, error) {
-	// wait until the lastConfirmedTimeTick is greater than barrierTimeTick.
-	ta.cond.L.Lock()
-	for ta.lastConfirmedTimeTick <= barrierTimeTick {
-		if err := ta.cond.Wait(ctx); err != nil {
-			return nil, err
-		}
+	// Just make a barrier to the underlying allocator.
+	if err := resource.Resource().TSOAllocator().BarrierUntil(ctx, barrierTimeTick); err != nil {
+		return nil, err
 	}
-	ta.cond.L.Unlock()
-
 	return ta.Allocate(ctx)
 }
 
 // Allocate allocates a timestamp.
 // Concurrent safe to call with Sync and Allocate.
 func (ta *AckManager) Allocate(ctx context.Context) (*Acker, error) {
-	ta.cond.L.Lock()
-	defer ta.cond.L.Unlock()
+	ta.mu.Lock()
+	defer ta.mu.Unlock()
 
 	// allocate one from underlying allocator first.
 	ts, err := resource.Resource().TSOAllocator().Allocate(ctx)
@@ -97,8 +91,8 @@ func (ta *AckManager) SyncAndGetAcknowledged(ctx context.Context) ([]*AckDetail,
 	}
 	tsWithAck.Ack(OptSync())
 
-	ta.cond.L.Lock()
-	defer ta.cond.L.Unlock()
+	ta.mu.Lock()
+	defer ta.mu.Unlock()
 
 	details := ta.acknowledgedDetails
 	ta.acknowledgedDetails = make(sortedDetails, 0, 5)
@@ -107,8 +101,8 @@ func (ta *AckManager) SyncAndGetAcknowledged(ctx context.Context) ([]*AckDetail,
 
 // ack marks the timestamp as acknowledged.
 func (ta *AckManager) ack(acker *Acker) {
-	ta.cond.L.Lock()
-	defer ta.cond.L.Unlock()
+	ta.mu.Lock()
+	defer ta.mu.Unlock()
 
 	acker.acknowledged = true
 	acker.detail.EndTimestamp = ta.lastAllocatedTimeTick
@@ -129,9 +123,6 @@ func (ta *AckManager) popUntilLastAllAcknowledged() {
 		return
 	}
 
-	// broadcast to notify the last confirmed timetick updated.
-	ta.cond.UnsafeBroadcast()
-
 	// update last confirmed time tick.
 	ta.lastConfirmedTimeTick = acknowledgedDetails[len(acknowledgedDetails)-1].BeginTimestamp
 	ta.metrics.UpdateLastConfirmedTimeTick(ta.lastConfirmedTimeTick)