ConnPool check fd for bad conns (#1824)

* conncheck for badconn (#1821)

* format imports

* fix ut: pool with badconn

* fix unstable ut: should facilitate failover

* Revert "fix unstable ut: should facilitate failover"

This reverts commit c7eeca2a5c.

* fix test error

Signed-off-by: monkey92t <golang@88.com>

Co-authored-by: hidu <duv123+github@gmail.com>
Co-authored-by: monkey92t <golang@88.com>

internal/pool/conncheck.go

@@ -0,0 +1,45 @@
+// +build linux darwin dragonfly freebsd netbsd openbsd solaris illumos
+
+package pool
+
+import (
+	"errors"
+	"io"
+	"net"
+	"syscall"
+)
+
+var errUnexpectedRead = errors.New("unexpected read from socket")
+
+func connCheck(conn net.Conn) error {
+	sysConn, ok := conn.(syscall.Conn)
+	if !ok {
+		return nil
+	}
+	rawConn, err := sysConn.SyscallConn()
+	if err != nil {
+		return err
+	}
+
+	var sysErr error
+	err = rawConn.Read(func(fd uintptr) bool {
+		var buf [1]byte
+		n, err := syscall.Read(int(fd), buf[:])
+		switch {
+		case n == 0 && err == nil:
+			sysErr = io.EOF
+		case n > 0:
+			sysErr = errUnexpectedRead
+		case err == syscall.EAGAIN || err == syscall.EWOULDBLOCK:
+			sysErr = nil
+		default:
+			sysErr = err
+		}
+		return true
+	})
+	if err != nil {
+		return err
+	}
+
+	return sysErr
+}

internal/pool/conncheck_dummy.go

@@ -0,0 +1,9 @@
+// +build !linux,!darwin,!dragonfly,!freebsd,!netbsd,!openbsd,!solaris,!illumos
+
+package pool
+
+import "net"
+
+func connCheck(conn net.Conn) error {
+	return nil
+}

internal/pool/conncheck_test.go

@@ -0,0 +1,46 @@
+// +build linux darwin dragonfly freebsd netbsd openbsd solaris illumos
+
+package pool
+
+import (
+	"net"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+func Test_connCheck(t *testing.T) {
+	// tests with real conns
+	ts := httptest.NewServer(nil)
+	defer ts.Close()
+
+	t.Run("good conn", func(t *testing.T) {
+		conn, err := net.DialTimeout(ts.Listener.Addr().Network(), ts.Listener.Addr().String(), time.Second)
+		if err != nil {
+			t.Fatalf(err.Error())
+		}
+		defer conn.Close()
+		if err = connCheck(conn); err != nil {
+			t.Fatalf(err.Error())
+		}
+		conn.Close()
+
+		if err = connCheck(conn); err == nil {
+			t.Fatalf("expect has error")
+		}
+	})
+
+	t.Run("bad conn 2", func(t *testing.T) {
+		conn, err := net.DialTimeout(ts.Listener.Addr().Network(), ts.Listener.Addr().String(), time.Second)
+		if err != nil {
+			t.Fatalf(err.Error())
+		}
+		defer conn.Close()
+
+		ts.Close()
+
+		if err = connCheck(conn); err == nil {
+			t.Fatalf("expect has err")
+		}
+	})
+}

internal/pool/main_test.go

@@ -2,9 +2,12 @@ package pool_test
 
 import (
 	"context"
+	"fmt"
 	"net"
 	"sync"
+	"syscall"
 	"testing"
+	"time"
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -32,5 +35,87 @@ func perform(n int, cbs ...func(int)) {
 }
 
 func dummyDialer(context.Context) (net.Conn, error) {
-	return &net.TCPConn{}, nil
+	// return &net.TCPConn{}, nil
+	return newDummyConn(), nil
+}
+
+func newDummyConn() net.Conn {
+	return &dummyConn{
+		rawConn: &dummyRawConn{},
+	}
+}
+
+var _ net.Conn = (*dummyConn)(nil)
+var _ syscall.Conn = (*dummyConn)(nil)
+
+type dummyConn struct {
+	rawConn *dummyRawConn
+}
+
+func (d *dummyConn) SyscallConn() (syscall.RawConn, error) {
+	return d.rawConn, nil
+}
+
+var errDummy = fmt.Errorf("dummyConn err")
+
+func (d *dummyConn) Read(b []byte) (n int, err error) {
+	return 0, errDummy
+}
+
+func (d *dummyConn) Write(b []byte) (n int, err error) {
+	return 0, errDummy
+}
+
+func (d *dummyConn) Close() error {
+	d.rawConn.Close()
+	return nil
+}
+
+func (d *dummyConn) LocalAddr() net.Addr {
+	return &net.TCPAddr{}
+}
+
+func (d *dummyConn) RemoteAddr() net.Addr {
+	return &net.TCPAddr{}
+}
+
+func (d *dummyConn) SetDeadline(t time.Time) error {
+	return nil
+}
+
+func (d *dummyConn) SetReadDeadline(t time.Time) error {
+	return nil
+}
+
+func (d *dummyConn) SetWriteDeadline(t time.Time) error {
+	return nil
+}
+
+var _ syscall.RawConn = (*dummyRawConn)(nil)
+
+type dummyRawConn struct {
+	closed bool
+	mux    sync.Mutex
+}
+
+func (d *dummyRawConn) Control(f func(fd uintptr)) error {
+	return nil
+}
+
+func (d *dummyRawConn) Read(f func(fd uintptr) (done bool)) error {
+	d.mux.Lock()
+	defer d.mux.Unlock()
+	if d.closed {
+		return fmt.Errorf("dummyRawConn closed")
+	}
+	return nil
+}
+
+func (d *dummyRawConn) Write(f func(fd uintptr) (done bool)) error {
+	return nil
+}
+func (d *dummyRawConn) Close() {
+	d.mux.Lock()
+	d.closed = true
+	d.mux.Unlock()
 }

internal/pool/pool.go

@@ -520,7 +520,7 @@ func (p *ConnPool) reapStaleConn() *Conn {
 
 func (p *ConnPool) isStaleConn(cn *Conn) bool {
 	if p.opt.IdleTimeout == 0 && p.opt.MaxConnAge == 0 {
-		return false
+		return connCheck(cn.netConn) != nil
 	}
 
 	now := time.Now()
@@ -531,5 +531,5 @@ func (p *ConnPool) isStaleConn(cn *Conn) bool {
 		return true
 	}
 
-	return false
+	return connCheck(cn.netConn) != nil
 }

internal/pool/pool_test.go

@@ -6,10 +6,10 @@ import (
 	"testing"
 	"time"
 
-	"github.com/go-redis/redis/v8/internal/pool"
-
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
+
+	"github.com/go-redis/redis/v8/internal/pool"
 )
 
 var _ = Describe("ConnPool", func() {
@@ -285,6 +285,8 @@ var _ = Describe("conns reaper", func() {
 					cn.SetUsedAt(time.Now().Add(-2 * idleTimeout))
 				case "aged":
 					cn.SetCreatedAt(time.Now().Add(-2 * maxAge))
+				case "conncheck":
+					cn.Close()
 				}
 				conns = append(conns, cn)
 				staleConns = append(staleConns, cn)
@@ -371,6 +373,7 @@ var _ = Describe("conns reaper", func() {
 
 	assert("idle")
 	assert("aged")
+	assert("conncheck")
 })
 
 var _ = Describe("race", func() {

main_test.go

@@ -12,10 +12,10 @@ import (
 	"testing"
 	"time"
 
-	"github.com/go-redis/redis/v8"
-
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
+
+	"github.com/go-redis/redis/v8"
 )
 
 const (
@@ -117,7 +117,7 @@ func TestGinkgoSuite(t *testing.T) {
 	RunSpecs(t, "go-redis")
 }
 
-//------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------
 
 func redisOptions() *redis.Options {
 	return &redis.Options{
@@ -364,7 +364,7 @@ func startSentinel(port, masterName, masterPort string) (*redisProcess, error) {
 	return p, nil
 }
 
-//------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------
 
 type badConnError string
 
@@ -409,7 +409,7 @@ func (cn *badConn) Write([]byte) (int, error) {
 	return 0, badConnError("bad connection")
 }
 
-//------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------
 
 type hook struct {
 	beforeProcess func(ctx context.Context, cmd redis.Cmder) (context.Context, error)

pool_test.go

@@ -87,8 +87,9 @@ var _ = Describe("pool", func() {
 		cn.SetNetConn(&badConn{})
 		client.Pool().Put(ctx, cn)
 
+		// connCheck will automatically remove damaged connections.
 		err = client.Ping(ctx).Err()
-		Expect(err).To(MatchError("bad connection"))
+		Expect(err).NotTo(HaveOccurred())
 
 		val, err := client.Ping(ctx).Result()
 		Expect(err).NotTo(HaveOccurred())

sentinel_test.go

@@ -191,7 +191,7 @@ var _ = Describe("NewFailoverClusterClient", func() {
 		err = master.Shutdown(ctx).Err()
 		Expect(err).NotTo(HaveOccurred())
 		Eventually(func() error {
-			return sentinelMaster.Ping(ctx).Err()
+			return master.Ping(ctx).Err()
 		}, "15s", "100ms").Should(HaveOccurred())
 
 		// Check that client picked up new master.

tx_test.go

@@ -123,7 +123,7 @@ var _ = Describe("Tx", func() {
 		Expect(num).To(Equal(int64(N)))
 	})
 
-	It("should recover from bad connection", func() {
+	It("should remove from bad connection", func() {
 		// Put bad connection in the pool.
 		cn, err := client.Pool().Get(context.Background())
 		Expect(err).NotTo(HaveOccurred())
@@ -134,17 +134,14 @@ var _ = Describe("Tx", func() {
 		do := func() error {
 			err := client.Watch(ctx, func(tx *redis.Tx) error {
 				_, err := tx.TxPipelined(ctx, func(pipe redis.Pipeliner) error {
-					pipe.Ping(ctx)
+					return pipe.Ping(ctx).Err()
-					return nil
 				})
 				return err
 			})
 			return err
 		}
 
-		err = do()
+		// connCheck will automatically remove damaged connections.
-		Expect(err).To(MatchError("bad connection"))
-
 		err = do()
 		Expect(err).NotTo(HaveOccurred())
 	})