GODRIVER-3516 Fix the issue in getOrQueueForIdleConn where connectionPerished conn.…

x/mongo/driver/topology/connection.go

@@ -14,7 +14,6 @@ import (
 	"fmt"
 	"io"
 	"net"
-	"os"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -526,48 +525,6 @@ func (c *connection) closed() bool {
 	return atomic.LoadInt64(&c.state) == connDisconnected
 }
 
-// isAlive returns true if the connection is alive and ready to be used for an
-// operation.
-//
-// Note that the liveness check can be slow (at least 1ms), so isAlive only
-// checks the liveness of the connection if it's been idle for at least 10
-// seconds. For frequently in-use connections, a network error during an
-// operation will be the first indication of a dead connection.
-func (c *connection) isAlive() bool {
-	if c.nc == nil {
-		return false
-	}
-
-	// If the connection has been idle for less than 10 seconds, skip the
-	// liveness check.
-	//
-	// The 10-seconds idle bypass is based on the liveness check implementation
-	// in the Python Driver. That implementation uses 1 second as the idle
-	// threshold, but we chose to be more conservative in the Go Driver because
-	// this is new behavior with unknown side-effects. See
-	// https://github.com/mongodb/mongo-python-driver/blob/e6b95f65953e01e435004af069a6976473eaf841/pymongo/synchronous/pool.py#L983-L985
-	idleStart, ok := c.idleStart.Load().(time.Time)
-	if !ok || idleStart.Add(10*time.Second).After(time.Now()) {
-		return true
-	}
-
-	// Set a 1ms read deadline and attempt to read 1 byte from the connection.
-	// Expect it to block for 1ms then return a deadline exceeded error. If it
-	// returns any other error, the connection is not usable, so return false.
-	// If it doesn't return an error and actually reads data, the connection is
-	// also not usable, so return false.
-	//
-	// Note that we don't need to un-set the read deadline because the "read"
-	// and "write" methods always reset the deadlines.
-	err := c.nc.SetReadDeadline(time.Now().Add(1 * time.Millisecond))
-	if err != nil {
-		return false
-	}
-	var b [1]byte
-	_, err = c.nc.Read(b[:])
-	return errors.Is(err, os.ErrDeadlineExceeded)
-}
-
 func (c *connection) idleTimeoutExpired() bool {
 	if c.idleTimeout == 0 {
 		return false

x/mongo/driver/topology/connection_test.go

@@ -1161,85 +1161,3 @@ func TestConnectionError(t *testing.T) {
 		assert.ErrorContains(t, err, "client timed out waiting for server response")
 	})
 }
-
-func TestConnection_IsAlive(t *testing.T) {
-	t.Parallel()
-
-	t.Run("uninitialized", func(t *testing.T) {
-		t.Parallel()
-
-		conn := newConnection("")
-		assert.False(t,
-			conn.isAlive(),
-			"expected isAlive for an uninitialized connection to always return false")
-	})
-
-	t.Run("connection open", func(t *testing.T) {
-		t.Parallel()
-
-		cleanup := make(chan struct{})
-		defer close(cleanup)
-		addr := bootstrapConnections(t, 1, func(nc net.Conn) {
-			// Keep the connection open until the end of the test.
-			<-cleanup
-			_ = nc.Close()
-		})
-
-		conn := newConnection(address.Address(addr.String()))
-		err := conn.connect(context.Background())
-		require.NoError(t, err)
-
-		conn.idleStart.Store(time.Now().Add(-11 * time.Second))
-		assert.True(t,
-			conn.isAlive(),
-			"expected isAlive for an open connection to return true")
-	})
-
-	t.Run("connection closed", func(t *testing.T) {
-		t.Parallel()
-
-		conns := make(chan net.Conn)
-		addr := bootstrapConnections(t, 1, func(nc net.Conn) {
-			conns <- nc
-		})
-
-		conn := newConnection(address.Address(addr.String()))
-		err := conn.connect(context.Background())
-		require.NoError(t, err)
-
-		// Close the connection before calling isAlive.
-		nc := <-conns
-		err = nc.Close()
-		require.NoError(t, err)
-
-		conn.idleStart.Store(time.Now().Add(-11 * time.Second))
-		assert.False(t,
-			conn.isAlive(),
-			"expected isAlive for a closed connection to return false")
-	})
-
-	t.Run("connection reads data", func(t *testing.T) {
-		t.Parallel()
-
-		cleanup := make(chan struct{})
-		defer close(cleanup)
-		addr := bootstrapConnections(t, 1, func(nc net.Conn) {
-			// Write some data to the connection before calling isAlive.
-			_, err := nc.Write([]byte{5, 0, 0, 0, 0})
-			require.NoError(t, err)
-
-			// Keep the connection open until the end of the test.
-			<-cleanup
-			_ = nc.Close()
-		})
-
-		conn := newConnection(address.Address(addr.String()))
-		err := conn.connect(context.Background())
-		require.NoError(t, err)
-
-		conn.idleStart.Store(time.Now().Add(-11 * time.Second))
-		assert.False(t,
-			conn.isAlive(),
-			"expected isAlive for an open connection that reads data to return false")
-	})
-}

x/mongo/driver/topology/pool.go

@@ -169,11 +169,9 @@ type reason struct {
 // connectionPerished checks if a given connection is perished and should be removed from the pool.
 func connectionPerished(conn *connection) (reason, bool) {
 	switch {
-	case conn.closed() || !conn.isAlive():
+	case conn.closed():
 		// A connection would only be closed if it encountered a network error
-		// during an operation and closed itself. If a connection is not alive
-		// (e.g. the connection was closed by the server-side), it's also
-		// considered a network error.
+		// during an operation and closed itself.
 		return reason{
 			loggerConn: logger.ReasonConnClosedError,
 			event:      event.ReasonError,

x/mongo/driver/topology/pool_test.go

@@ -843,79 +843,6 @@ func TestPool_checkOut(t *testing.T) {
 			assert.Containsf(t, err.Error(), "canceled", `expected error message to contain "canceled"`)
 		}
 
-		p.close(context.Background())
-	})
-	t.Run("discards connections closed by the server side", func(t *testing.T) {
-		t.Parallel()
-
-		cleanup := make(chan struct{})
-		defer close(cleanup)
-
-		ncs := make(chan net.Conn, 2)
-		addr := bootstrapConnections(t, 2, func(nc net.Conn) {
-			// Send all "server-side" connections to a channel so we can
-			// interact with them during the test.
-			ncs <- nc
-
-			<-cleanup
-			_ = nc.Close()
-		})
-
-		d := newdialer(&net.Dialer{})
-		p := newPool(poolConfig{
-			Address: address.Address(addr.String()),
-		}, WithDialer(func(Dialer) Dialer { return d }))
-		err := p.ready()
-		require.NoError(t, err)
-
-		// Add 1 idle connection to the pool by checking-out and checking-in
-		// a connection.
-		conn, err := p.checkOut(context.Background())
-		require.NoError(t, err)
-		err = p.checkIn(conn)
-		require.NoError(t, err)
-		assertConnectionsOpened(t, d, 1)
-		assert.Equalf(t, 1, p.availableConnectionCount(), "should be 1 idle connections in pool")
-		assert.Equalf(t, 1, p.totalConnectionCount(), "should be 1 total connection in pool")
-
-		// Make that connection appear as if it's been idle for a minute.
-		conn.idleStart.Store(time.Now().Add(-1 * time.Minute))
-
-		// Close the "server-side" of the connection we just created. The idle
-		// connection in the pool is now unusable because the "server-side"
-		// closed it.
-		nc := <-ncs
-		err = nc.Close()
-		require.NoError(t, err)
-
-		// In a separate goroutine, write a valid wire message to the 2nd
-		// connection that's about to be created. Stop waiting for a 2nd
-		// connection after 100ms to prevent leaking a goroutine.
-		go func() {
-			select {
-			case nc := <-ncs:
-				_, err := nc.Write([]byte{5, 0, 0, 0, 0})
-				require.NoError(t, err, "Write error")
-			case <-time.After(100 * time.Millisecond):
-			}
-		}()
-
-		// Check out a connection and try to read from it. Expect the pool to
-		// discard the connection that was closed by the "server-side" and
-		// return a newly created connection instead.
-		conn, err = p.checkOut(context.Background())
-		require.NoError(t, err)
-		msg, err := conn.readWireMessage(context.Background())
-		require.NoError(t, err)
-		assert.Equal(t, []byte{5, 0, 0, 0, 0}, msg)
-
-		err = p.checkIn(conn)
-		require.NoError(t, err)
-
-		assertConnectionsOpened(t, d, 2)
-		assert.Equalf(t, 1, p.availableConnectionCount(), "should be 1 idle connections in pool")
-		assert.Equalf(t, 1, p.totalConnectionCount(), "should be 1 total connection in pool")
-
 		p.close(context.Background())
 	})
 }