use correct timer for last health check

internal/pool/conn.go

@@ -81,7 +81,8 @@ type Conn struct {
 	// Connection identifier for unique tracking
 	id uint64
 
-	usedAt int64 // atomic
+	usedAt    atomic.Int64
+	lastPutAt atomic.Int64
 
 	// Lock-free netConn access using atomic.Value
 	// Contains *atomicNetConn wrapper, accessed atomically for better performance
@@ -175,15 +176,24 @@ func NewConnWithBufferSize(netConn net.Conn, readBufSize, writeBufSize int) *Con
 }
 
 func (cn *Conn) UsedAt() time.Time {
-	unixNano := atomic.LoadInt64(&cn.usedAt)
-	return time.Unix(0, unixNano)
+	return time.Unix(0, cn.usedAt.Load())
 }
-func (cn *Conn) UsedAtNs() int64 {
-	return atomic.LoadInt64(&cn.usedAt)
+func (cn *Conn) SetUsedAt(tm time.Time) {
+	cn.usedAt.Store(tm.UnixNano())
 }
 
-func (cn *Conn) SetUsedAt(tm time.Time) {
-	atomic.StoreInt64(&cn.usedAt, tm.UnixNano())
+func (cn *Conn) UsedAtNs() int64 {
+	return cn.usedAt.Load()
+}
+func (cn *Conn) SetUsedAtNs(ns int64) {
+	cn.usedAt.Store(ns)
+}
+
+func (cn *Conn) LastPutAtNs() int64 {
+	return cn.lastPutAt.Load()
+}
+func (cn *Conn) SetLastPutAtNs(ns int64) {
+	cn.lastPutAt.Store(ns)
 }
 
 // Backward-compatible wrapper methods for state machine

internal/pool/pool.go

@@ -461,7 +461,7 @@ func (p *ConnPool) getConn(ctx context.Context) (*Conn, error) {
 	}
 
 	// Use cached time for health checks (max 50ms staleness is acceptable)
-	now := time.Unix(0, getCachedTimeNs())
+	nowNs := getCachedTimeNs()
 	attempts := 0
 
 	// Lock-free atomic read - no mutex overhead!
@@ -487,7 +487,7 @@ func (p *ConnPool) getConn(ctx context.Context) (*Conn, error) {
 			break
 		}
 
-		if !p.isHealthyConn(cn, now) {
+		if !p.isHealthyConn(cn, nowNs) {
 			_ = p.CloseConn(cn)
 			continue
 		}
@@ -742,6 +742,8 @@ func (p *ConnPool) putConn(ctx context.Context, cn *Conn, freeTurn bool) {
 	if shouldCloseConn {
 		_ = p.closeConn(cn)
 	}
+
+	cn.SetLastPutAtNs(getCachedTimeNs())
 }
 
 func (p *ConnPool) Remove(ctx context.Context, cn *Conn, reason error) {
@@ -891,14 +893,14 @@ func (p *ConnPool) Close() error {
 	return firstErr
 }
 
-func (p *ConnPool) isHealthyConn(cn *Conn, now time.Time) bool {
+func (p *ConnPool) isHealthyConn(cn *Conn, nowNs int64) bool {
 	// Performance optimization: check conditions from cheapest to most expensive,
 	// and from most likely to fail to least likely to fail.
 
 	// Only fails if ConnMaxLifetime is set AND connection is old.
 	// Most pools don't set ConnMaxLifetime, so this rarely fails.
 	if p.cfg.ConnMaxLifetime > 0 {
-		if cn.expiresAt.Before(now) {
+		if cn.expiresAt.UnixNano() < nowNs {
 			return false // Connection has exceeded max lifetime
 		}
 	}
@@ -906,7 +908,7 @@ func (p *ConnPool) isHealthyConn(cn *Conn, now time.Time) bool {
 	// Most pools set ConnMaxIdleTime, and idle connections are common.
 	// Checking this first allows us to fail fast without expensive syscalls.
 	if p.cfg.ConnMaxIdleTime > 0 {
-		if now.Sub(cn.UsedAt()) >= p.cfg.ConnMaxIdleTime {
+		if nowNs-cn.UsedAtNs() >= int64(p.cfg.ConnMaxIdleTime) {
 			return false // Connection has been idle too long
 		}
 	}
@@ -926,7 +928,7 @@ func (p *ConnPool) isHealthyConn(cn *Conn, now time.Time) bool {
 				)
 
 				// Update timestamp for healthy connection
-				cn.SetUsedAt(now)
+				cn.SetUsedAtNs(nowNs)
 
 				// Connection is healthy, client will handle notifications
 				return true
@@ -939,6 +941,6 @@ func (p *ConnPool) isHealthyConn(cn *Conn, now time.Time) bool {
 	}
 
 	// Only update UsedAt if connection is healthy (avoids unnecessary atomic store)
-	cn.SetUsedAt(now)
+	cn.SetUsedAtNs(nowNs)
 	return true
 }

redis.go

@@ -1366,11 +1366,13 @@ func (c *baseClient) processPushNotifications(ctx context.Context, cn *pool.Conn
 	// If the connection was health-checked within the last 5 seconds, we can skip the
 	// expensive syscall since the health check already verified no unexpected data.
 	// This is safe because:
+	// 0. lastHealthCheckNs is set in pool/conn.go:putConn() after a successful health check
 	// 1. Health check (connCheck) uses the same syscall (Recvfrom with MSG_PEEK)
 	// 2. If push notifications arrived, they would have been detected by health check
 	// 3. 5 seconds is short enough that connection state is still fresh
 	// 4. Push notifications will be processed by the next WithReader call
-	lastHealthCheckNs := cn.UsedAtNs()
+	// used it is set on getConn, so we should use another timer (lastPutAt?)
+	lastHealthCheckNs := cn.LastPutAtNs()
 	if lastHealthCheckNs > 0 {
 		// Use pool's cached time to avoid expensive time.Now() syscall
 		nowNs := pool.GetCachedTimeNs()