Bug fix: Mark connection as not good when error on cancellation confirmation

mssql.go

@@ -228,6 +228,8 @@ func (c *Conn) checkBadConn(ctx context.Context, err error, mayRetry bool) error
 		return nil
 	case io.EOF:
 		c.connectionGood = false
+	case ErrorCancelConfirmation:
+		c.connectionGood = false
 	case driver.ErrBadConn:
 		// It is an internal programming error if driver.ErrBadConn
 		// is ever passed to this function. driver.ErrBadConn should

mssql_test.go

@@ -127,6 +127,10 @@ func TestCheckBadConn(t *testing.T) {
 		{io.EOF, true, false, newRetryableError(io.EOF), false},
 		{io.EOF, false, true, io.EOF, false},
 		{io.EOF, true, true, io.EOF, false},
+		{ErrorCancelConfirmation, false, false, ErrorCancelConfirmation, false},
+		{ErrorCancelConfirmation, true, false, newRetryableError(ErrorCancelConfirmation), false},
+		{ErrorCancelConfirmation, false, true, ErrorCancelConfirmation, false},
+		{ErrorCancelConfirmation, true, true, ErrorCancelConfirmation, false},
 		{netErr, false, false, netErr, false},
 		{netErr, true, false, newRetryableError(netErr), false},
 		{netErr, false, true, netErr, false},

queries_test.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -1370,6 +1371,46 @@ func TestProcessQueryErrors(t *testing.T) {
 	}
 }
 
+type mockReadWriteCloser struct {
+	io.ReadWriteCloser
+}
+
+func (*mockReadWriteCloser) Read([]byte) (int, error) { return 0, errors.New("fake err") }
+
+func TestProcessQueryCancelConfirmationError(t *testing.T) {
+	tl := testLogger{t: t}
+	defer tl.StopLogging()
+	conn := internalConnection(t, &tl)
+	defer conn.Close()
+
+	stmt, err := conn.prepareContext(context.Background(), "select 1")
+	if err != nil {
+		t.Fatal("prepareContext expected to succeed, but it failed with", err)
+	}
+	err = stmt.sendQuery(context.Background(), []namedValue{})
+	if err != nil {
+		t.Fatal("sendQuery expected to succeed, but it failed with", err)
+	}
+	// mock real connection to imitate situation when you write but dont get response
+	conn.sess.buf.transport = &mockReadWriteCloser{ReadWriteCloser: conn.sess.buf.transport}
+	// canceling context to try to send attention request
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	_, err = stmt.processQueryResponse(ctx)
+	if err == nil {
+		t.Error("processQueryResponse expected to fail but it succeeded")
+	}
+	// should not fail with ErrBadConn because query was successfully sent to server
+	if err != ErrorCancelConfirmation {
+		t.Error("processQueryResponse expected to fail with ErrorCancelConfirmation error but failed with other error: ", err)
+	}
+
+	if conn.connectionGood {
+		t.Fatal("Connection should be in a bad state")
+	}
+}
+
 func TestProcessQueryNextErrors(t *testing.T) {
 	tl := testLogger{t: t}
 	defer tl.StopLogging()

token.go

@@ -85,6 +85,8 @@ const (
 	// TODO implement more flags
 )
 
+var ErrorCancelConfirmation = errors.New("did not get cancellation confirmation from the server")
+
 // interface for all tokens
 type tokenStruct interface{}
 
@@ -934,7 +936,7 @@ func (t tokenProcessor) nextToken() (tokenStruct, error) {
 		}
 		// we did not get cancellation confirmation, something is not
 		// right, this connection is not usable anymore
-		return nil, errors.New("did not get cancellation confirmation from the server")
+		return nil, ErrorCancelConfirmation
 	}
 }