[WIP] hitless

async_handoff_integration_test.go

@@ -52,7 +52,7 @@ func TestEventDrivenHandoffIntegration(t *testing.T) {
 			Dialer: func(ctx context.Context) (net.Conn, error) {
 				return &mockNetConn{addr: "original:6379"}, nil
 			},
-			PoolSize:    5,
+			PoolSize:    int32(5),
 			PoolTimeout: time.Second,
 		})
 
@@ -144,8 +144,8 @@ func TestEventDrivenHandoffIntegration(t *testing.T) {
 			Dialer: func(ctx context.Context) (net.Conn, error) {
 				return &mockNetConn{addr: "original:6379"}, nil
 			},
-			
-			PoolSize:       10,
+
+			PoolSize:       int32(10),
 			PoolTimeout:    time.Second,
 		})
 		defer testPool.Close()
@@ -216,8 +216,8 @@ func TestEventDrivenHandoffIntegration(t *testing.T) {
 			Dialer: func(ctx context.Context) (net.Conn, error) {
 				return &mockNetConn{addr: "original:6379"}, nil
 			},
-			
-			PoolSize:       3,
+
+			PoolSize:       int32(3),
 			PoolTimeout:    time.Second,
 		})
 		defer testPool.Close()
@@ -279,8 +279,8 @@ func TestEventDrivenHandoffIntegration(t *testing.T) {
 			Dialer: func(ctx context.Context) (net.Conn, error) {
 				return &mockNetConn{addr: "original:6379"}, nil
 			},
-			
-			PoolSize:       2,
+
+			PoolSize:       int32(2),
 			PoolTimeout:    time.Second,
 		})
 		defer testPool.Close()

hitless/pool_hook.go

@@ -124,15 +124,14 @@ func (ph *PoolHook) GetScaleLevel() int {
 	return ph.scaleLevel
 }
 
-
 // IsHandoffPending returns true if the given connection has a pending handoff
 func (ph *PoolHook) IsHandoffPending(conn *pool.Conn) bool {
 	_, pending := ph.pending.Load(conn.GetID())
 	return pending
 }
 
 // OnGet is called when a connection is retrieved from the pool
-func (ph *PoolHook) OnGet(ctx context.Context, conn *pool.Conn, _ bool) error {
+func (ph *PoolHook) OnGet(ctx context.Context, conn *pool.Conn, isNewConn bool) error {
 	// NOTE: There are two conditions to make sure we don't return a connection that should be handed off or is
 	// in a handoff state at the moment.
 
@@ -508,7 +507,7 @@ func (ph *PoolHook) performConnectionHandoffWithPool(ctx context.Context, conn *
 	oldConn := conn.GetNetConn()
 
 	// Replace the connection and execute initialization
-	err = conn.SetNetConnWithInitConn(ctx, newNetConn)
+	err = conn.SetNetConnAndInitConn(ctx, newNetConn)
 	if err != nil {
 		// Remove the connection from the pool since it's in a bad state
 		if pooler != nil {

internal/pool/bench_test.go

@@ -2,6 +2,7 @@ package pool_test
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"testing"
 	"time"
@@ -31,7 +32,7 @@ func BenchmarkPoolGetPut(b *testing.B) {
 		b.Run(bm.String(), func(b *testing.B) {
 			connPool := pool.NewConnPool(&pool.Options{
 				Dialer:          dummyDialer,
-				PoolSize:        bm.poolSize,
+				PoolSize:        int32(bm.poolSize),
 				PoolTimeout:     time.Second,
 				DialTimeout:     1 * time.Second,
 				ConnMaxIdleTime: time.Hour,
@@ -75,7 +76,7 @@ func BenchmarkPoolGetRemove(b *testing.B) {
 		b.Run(bm.String(), func(b *testing.B) {
 			connPool := pool.NewConnPool(&pool.Options{
 				Dialer:          dummyDialer,
-				PoolSize:        bm.poolSize,
+				PoolSize:        int32(bm.poolSize),
 				PoolTimeout:     time.Second,
 				DialTimeout:     1 * time.Second,
 				ConnMaxIdleTime: time.Hour,
@@ -89,7 +90,7 @@ func BenchmarkPoolGetRemove(b *testing.B) {
 					if err != nil {
 						b.Fatal(err)
 					}
-					connPool.Remove(ctx, cn, nil)
+					connPool.Remove(ctx, cn, errors.New("Bench test remove"))
 				}
 			})
 		})

internal/pool/buffer_size_test.go

@@ -26,7 +26,7 @@ var _ = Describe("Buffer Size Configuration", func() {
 	It("should use default buffer sizes when not specified", func() {
 		connPool = pool.NewConnPool(&pool.Options{
 			Dialer:      dummyDialer,
-			PoolSize:    1,
+			PoolSize:    int32(1),
 			PoolTimeout: 1000,
 		})
 
@@ -48,7 +48,7 @@ var _ = Describe("Buffer Size Configuration", func() {
 
 		connPool = pool.NewConnPool(&pool.Options{
 			Dialer:          dummyDialer,
-			PoolSize:        1,
+			PoolSize:        int32(1),
 			PoolTimeout:     1000,
 			ReadBufferSize:  customReadSize,
 			WriteBufferSize: customWriteSize,
@@ -69,7 +69,7 @@ var _ = Describe("Buffer Size Configuration", func() {
 	It("should handle zero buffer sizes by using defaults", func() {
 		connPool = pool.NewConnPool(&pool.Options{
 			Dialer:          dummyDialer,
-			PoolSize:        1,
+			PoolSize:        int32(1),
 			PoolTimeout:     1000,
 			ReadBufferSize:  0, // Should use default
 			WriteBufferSize: 0, // Should use default
@@ -105,7 +105,7 @@ var _ = Describe("Buffer Size Configuration", func() {
 		// without setting ReadBufferSize and WriteBufferSize
 		connPool = pool.NewConnPool(&pool.Options{
 			Dialer:      dummyDialer,
-			PoolSize:    1,
+			PoolSize:    int32(1),
 			PoolTimeout: 1000,
 			// ReadBufferSize and WriteBufferSize are not set (will be 0)
 		})

internal/pool/conn.go

@@ -43,7 +43,7 @@ type Conn struct {
 	// Only used for the brief period during SetNetConn and HasBufferedData/PeekReplyTypeSafe
 	readerMu sync.RWMutex
 
-	Inited    bool
+	Inited    atomic.Bool
 	pooled    bool
 	createdAt time.Time
 	expiresAt time.Time
@@ -200,6 +200,10 @@ func (cn *Conn) IsUsable() bool {
 	return cn.isUsable()
 }
 
+func (cn *Conn) IsInited() bool {
+	return cn.Inited.Load()
+}
+
 // SetUsable sets the usable flag for the connection (lock-free).
 func (cn *Conn) SetUsable(usable bool) {
 	cn.setUsable(usable)
@@ -347,12 +351,7 @@ func (cn *Conn) SetInitConnFunc(fn func(context.Context, *Conn) error) {
 // ExecuteInitConn runs the stored connection initialization function if available.
 func (cn *Conn) ExecuteInitConn(ctx context.Context) error {
 	if cn.initConnFunc != nil {
-		if err := cn.initConnFunc(ctx, cn); err != nil {
-			return err
-		}
-		cn.Inited = true
-		cn.setUsable(true) // Use atomic operation
-		return nil
+		return cn.initConnFunc(ctx, cn)
 	}
 	return fmt.Errorf("redis: no initConnFunc set for connection %d", cn.GetID())
 }
@@ -378,10 +377,10 @@ func (cn *Conn) GetNetConn() net.Conn {
 	return cn.getNetConn()
 }
 
-// SetNetConnWithInitConn replaces the underlying connection and executes the initialization.
-func (cn *Conn) SetNetConnWithInitConn(ctx context.Context, netConn net.Conn) error {
+// SetNetConnAndInitConn replaces the underlying connection and executes the initialization.
+func (cn *Conn) SetNetConnAndInitConn(ctx context.Context, netConn net.Conn) error {
 	// New connection is not initialized yet
-	cn.Inited = false
+	cn.Inited.Store(false)
 	// Replace the underlying connection
 	cn.SetNetConn(netConn)
 	return cn.ExecuteInitConn(ctx)

internal/pool/pool.go

@@ -76,15 +76,16 @@ type Options struct {
 	ReadBufferSize  int
 	WriteBufferSize int
 
-	PoolFIFO        bool
-	PoolSize        int
-	DialTimeout     time.Duration
-	PoolTimeout     time.Duration
-	MinIdleConns    int
-	MaxIdleConns    int
-	MaxActiveConns  int
-	ConnMaxIdleTime time.Duration
-	ConnMaxLifetime time.Duration
+	PoolFIFO                 bool
+	PoolSize                 int32
+	DialTimeout              time.Duration
+	PoolTimeout              time.Duration
+	MinIdleConns             int32
+	MaxIdleConns             int32
+	MaxActiveConns           int32
+	ConnMaxIdleTime          time.Duration
+	ConnMaxLifetime          time.Duration
+	PushNotificationsEnabled bool
 }
 
 type lastDialErrorWrap struct {
@@ -103,8 +104,9 @@ type ConnPool struct {
 	conns     []*Conn
 	idleConns []*Conn
 
-	poolSize     atomic.Int32
-	idleConnsLen int
+	poolSize            atomic.Int32
+	idleConnsLen        atomic.Int32
+	idleCheckInProgress atomic.Bool
 
 	stats          Stats
 	waitDurationNs atomic.Int64
@@ -161,23 +163,29 @@ func (p *ConnPool) RemovePoolHook(hook PoolHook) {
 }
 
 func (p *ConnPool) checkMinIdleConns() {
+
+	if !p.idleCheckInProgress.CompareAndSwap(false, true) {
+		return
+	}
+	defer p.idleCheckInProgress.Store(false)
+
 	if p.cfg.MinIdleConns == 0 {
 		return
 	}
 
 	// Only create idle connections if we haven't reached the total pool size limit
 	// MinIdleConns should be a subset of PoolSize, not additional connections
-	for p.poolSize.Load() < int32(p.cfg.PoolSize) && p.idleConnsLen < p.cfg.MinIdleConns {
+	for p.poolSize.Load() < p.cfg.PoolSize && p.idleConnsLen.Load() < p.cfg.MinIdleConns {
 		select {
 		case p.queue <- struct{}{}:
 			p.poolSize.Add(1)
-			p.idleConnsLen++
+			p.idleConnsLen.Add(1)
 			go func() {
 				defer func() {
 					if err := recover(); err != nil {
 						p.connsMu.Lock()
 						p.poolSize.Add(-1)
-						p.idleConnsLen--
+						p.idleConnsLen.Add(-1)
 						p.connsMu.Unlock()
 
 						p.freeTurn()
@@ -189,7 +197,7 @@ func (p *ConnPool) checkMinIdleConns() {
 				if err != nil && err != ErrClosed {
 					p.connsMu.Lock()
 					p.poolSize.Add(-1)
-					p.idleConnsLen--
+					p.idleConnsLen.Add(-1)
 					p.connsMu.Unlock()
 				}
 				p.freeTurn()
@@ -389,6 +397,7 @@ func (p *ConnPool) getConn(ctx context.Context) (*Conn, error) {
 		// Process connection using the hooks system
 		if p.hookManager != nil {
 			if err := p.hookManager.ProcessOnGet(ctx, cn, false); err != nil {
+				log.Printf("redis: connection pool: failed to process idle connection by hook: %v", err)
 				// Failed to process connection, discard it
 				_ = p.CloseConn(cn)
 				continue
@@ -490,7 +499,7 @@ func (p *ConnPool) popIdle() (*Conn, error) {
 		attempts++
 
 		if cn.IsUsable() {
-			p.idleConnsLen--
+			p.idleConnsLen.Add(-1)
 			break
 		}
 
@@ -543,28 +552,38 @@ func (p *ConnPool) Put(ctx context.Context, cn *Conn) {
 
 	// If hooks say to remove the connection, do so
 	if shouldRemove {
-		p.Remove(ctx, cn, nil)
+		p.Remove(ctx, cn, errors.New("hook requested removal"))
 		return
 	}
 
 	// If processor says not to pool the connection, remove it
 	if !shouldPool {
-		p.Remove(ctx, cn, nil)
+		p.Remove(ctx, cn, errors.New("hook requested no pooling"))
 		return
 	}
 
 	if !cn.pooled {
-		p.Remove(ctx, cn, nil)
+		p.Remove(ctx, cn, errors.New("connection not pooled"))
 		return
 	}
 
 	var shouldCloseConn bool
 
 	p.connsMu.Lock()
 
-	if p.cfg.MaxIdleConns == 0 || p.idleConnsLen < p.cfg.MaxIdleConns {
-		p.idleConns = append(p.idleConns, cn)
-		p.idleConnsLen++
+	if p.cfg.MaxIdleConns == 0 || p.idleConnsLen.Load() < p.cfg.MaxIdleConns {
+		// unusable conns are expected to become usable at some point (background process is reconnecting them)
+		// put them at the opposite end of the queue
+		if !cn.IsUsable() {
+			if p.cfg.PoolFIFO {
+				p.idleConns = append(p.idleConns, cn)
+			} else {
+				p.idleConns = append([]*Conn{cn}, p.idleConns...)
+			}
+		} else {
+			p.idleConns = append(p.idleConns, cn)
+		}
+		p.idleConnsLen.Add(1)
 	} else {
 		p.removeConn(cn)
 		shouldCloseConn = true
@@ -626,9 +645,9 @@ func (p *ConnPool) Len() int {
 // IdleLen returns number of idle connections.
 func (p *ConnPool) IdleLen() int {
 	p.connsMu.Lock()
-	n := p.idleConnsLen
+	n := p.idleConnsLen.Load()
 	p.connsMu.Unlock()
-	return n
+	return int(n)
 }
 
 func (p *ConnPool) Stats() *Stats {
@@ -680,7 +699,7 @@ func (p *ConnPool) Close() error {
 	p.conns = nil
 	p.poolSize.Store(0)
 	p.idleConns = nil
-	p.idleConnsLen = 0
+	p.idleConnsLen.Store(0)
 	p.connsMu.Unlock()
 
 	return firstErr
@@ -696,12 +715,26 @@ func (p *ConnPool) isHealthyConn(cn *Conn, now time.Time) bool {
 		return false
 	}
 
+	cn.SetUsedAt(now)
 	// Check basic connection health
 	// Use GetNetConn() to safely access netConn and avoid data races
 	if err := connCheck(cn.getNetConn()); err != nil {
-		return false
+		// If there's unexpected data, it might be push notifications (RESP3)
+		// However, push notification processing is now handled by the client
+		// before WithReader to ensure proper context is available to handlers
+		if p.cfg.PushNotificationsEnabled && err == errUnexpectedRead {
+			// we know that there is something in the buffer, so peek at the next reply type without
+			// the potential to block
+			if replyType, err := cn.rd.PeekReplyType(); err == nil && replyType == proto.RespPush {
+				// For RESP3 connections with push notifications, we allow some buffered data
+				// The client will process these notifications before using the connection
+				internal.Logger.Printf(context.Background(), "push: connection has buffered data, likely push notifications - will be processed by client")
+				return true // Connection is healthy, client will handle notifications
+			}
+			return false // Unexpected data, not push notifications, connection is unhealthy
+		} else {
+			return false
+		}
 	}
-
-	cn.SetUsedAt(now)
 	return true
 }

internal/pool/pool_single.go

@@ -1,6 +1,8 @@
 package pool
 
-import "context"
+import (
+	"context"
+)
 
 type SingleConnPool struct {
 	pool      Pooler