syncer/: add async flush checkpoint feature

pkg/atomic2/atomic.go

@@ -0,0 +1,38 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package atomic2
+
+import (
+	"sync/atomic"
+	"unsafe"
+)
+
+// AtomicError implements atomic error method
+type AtomicError struct {
+	p unsafe.Pointer
+}
+
+// Get returns error
+func (e *AtomicError) Get() error {
+	p := atomic.LoadPointer(&e.p)
+	if p == nil {
+		return nil
+	}
+	return *(*error)(p)
+}
+
+// Set sets error to AtomicError
+func (e *AtomicError) Set(err error) {
+	atomic.StorePointer(&e.p, unsafe.Pointer(&err))
+}

pkg/atomic2/atomic_test.go

@@ -0,0 +1,50 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package atomic2
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/pingcap/check"
+)
+
+func TestT(t *testing.T) {
+	check.TestingT(t)
+}
+
+var _ = check.Suite(&testAtomicSuite{})
+
+type testAtomicSuite struct{}
+
+func (t *testAtomicSuite) TestAtomicError(c *check.C) {
+	var (
+		e   AtomicError
+		err = errors.New("test")
+	)
+	err2 := e.Get()
+	c.Assert(err2, check.Equals, nil)
+
+	e.Set(err)
+	err2 = e.Get()
+	c.Assert(err2, check.DeepEquals, err)
+
+	err = errors.New("test2")
+	err2 = e.Get()
+	c.Assert(err2.Error(), check.Equals, "test")
+
+	e.Set(nil)
+	err2 = e.Get()
+	c.Assert(err2, check.Equals, nil)
+}

syncer/checkpoint.go

@@ -433,8 +433,8 @@ func (cp *RemoteCheckPoint) SaveGlobalPoint(location binlog.Location) {
 
 // FlushPointsExcept implements CheckPoint.FlushPointsExcept
 func (cp *RemoteCheckPoint) FlushPointsExcept(tctx *tcontext.Context, exceptTables [][]string, extraSQLs []string, extraArgs [][]interface{}) error {
-	cp.RLock()
-	defer cp.RUnlock()
+	cp.Lock()
+	defer cp.Unlock()
 
 	// convert slice to map
 	excepts := make(map[string]map[string]struct{})

syncer/optimist.go

@@ -214,8 +214,8 @@ func (s *Syncer) handleQueryEventOptimistic(
 		return err
 	}
 
-	if s.execErrorDetected.Get() {
-		return terror.ErrSyncerUnitHandleDDLFailed.Generate(ev.Query)
+	if err := s.execError.Get(); err != nil {
+		return terror.ErrSyncerUnitHandleDDLFailed.Delegate(err, ev.Query)
 	}
 
 	for _, table := range onlineDDLTableNames {