[Cherry-pick tidb-7.1] Check kill signals (#1186)

* fix: check kill signal against 0 (#1102)

* fix: check kill signal against 0, so that all kill signals will not be ignored.

Signed-off-by: ekexium <eke@fastmail.com>

* refactor: extract method checkKilled()

Signed-off-by: ekexium <eke@fastmail.com>

---------

Signed-off-by: ekexium <eke@fastmail.com>
Co-authored-by: cfzjywxk <lsswxrxr@163.com>

* ErrQueryInterrupted with parameters (#1124)

* feat: ErrQueryInterrupted with parameters

Signed-off-by: ekexium <eke@fastmail.com>

* Revert "Revert "fix: check kill signal against 0 (#1102)" (#1129)"

This reverts commit 3480b5e.

Signed-off-by: ekexium <eke@fastmail.com>

---------

Signed-off-by: ekexium <eke@fastmail.com>
Co-authored-by: cfzjywxk <lsswxrxr@163.com>

* rm backoff.go

Signed-off-by: ekexium <eke@fastmail.com>

---------

Signed-off-by: ekexium <eke@fastmail.com>
Co-authored-by: cfzjywxk <lsswxrxr@163.com>

error/error.go

@@ -64,7 +64,8 @@ var (
 	// ErrTiFlashServerTimeout is the error when tiflash server is timeout.
 	ErrTiFlashServerTimeout = errors.New("tiflash server timeout")
 	// ErrQueryInterrupted is the error when the query is interrupted.
-	ErrQueryInterrupted = errors.New("query interruppted")
+	// This is deprecated. Keep it only to pass CI :-(. We can remove this later.
+	ErrQueryInterrupted = errors.New("query interrupted")
 	// ErrTiKVStaleCommand is the error that the command is stale in tikv.
 	ErrTiKVStaleCommand = errors.New("tikv stale command")
 	// ErrTiKVMaxTimestampNotSynced is the error that tikv's max timestamp is not synced.
@@ -96,11 +97,19 @@ var (
 	// ErrIsWitness is the error when a request is send to a witness.
 	ErrIsWitness = errors.New("peer is witness")
 	// ErrUnknown is the unknow error.
-	ErrUnknown = errors.New("unknow")
+	ErrUnknown = errors.New("unknown")
 	// ErrResultUndetermined is the error when execution result is unknown.
 	ErrResultUndetermined = errors.New("execution result undetermined")
 )
 
+type ErrQueryInterruptedWithSignal struct {
+	Signal uint32
+}
+
+func (e ErrQueryInterruptedWithSignal) Error() string {
+	return fmt.Sprintf("query interrupted by signal %d", e.Signal)
+}
+
 // MismatchClusterID represents the message that the cluster ID of the PD client does not match the PD.
 const MismatchClusterID = "mismatch cluster id"
 

integration_tests/2pc_test.go

@@ -2502,3 +2502,13 @@ func (s *testCommitterSuite) TestExtractKeyExistsErr() {
 	s.True(txn.GetMemBuffer().TryLock())
 	txn.GetMemBuffer().Unlock()
 }
+
+func (s *testCommitterSuite) TestKillSignal() {
+	txn := s.begin()
+	err := txn.Set([]byte("key"), []byte("value"))
+	s.Nil(err)
+	var killed uint32 = 2
+	txn.SetVars(kv.NewVariables(&killed))
+	err = txn.Commit(context.Background())
+	s.ErrorContains(err, "query interrupted")
+}

internal/locate/region_request.go

@@ -1366,9 +1366,8 @@ func (s *RegionRequestSender) SendReqCtx(
 		}
 
 		// recheck whether the session/query is killed during the Next()
-		boVars := bo.GetVars()
-		if boVars != nil && boVars.Killed != nil && atomic.LoadUint32(boVars.Killed) == 1 {
-			return nil, nil, retryTimes, errors.WithStack(tikverr.ErrQueryInterrupted)
+		if err2 := bo.CheckKilled(); err2 != nil {
+			return nil, nil, retryTimes, err2
 		}
 		if val, err := util.EvalFailpoint("mockRetrySendReqToRegion"); err == nil {
 			if val.(bool) {

internal/retry/backoff.go

@@ -210,10 +210,9 @@ func (b *Backoffer) BackoffWithCfgAndMaxSleep(cfg *Config, maxSleepMs int, err e
 		atomic.AddInt64(&detail.BackoffCount, 1)
 	}
 
-	if b.vars != nil && b.vars.Killed != nil {
-		if atomic.LoadUint32(b.vars.Killed) == 1 {
-			return errors.WithStack(tikverr.ErrQueryInterrupted)
-		}
+	err2 := b.CheckKilled()
+	if err2 != nil {
+		return err2
 	}
 
 	var startTs interface{}
@@ -375,3 +374,17 @@ func (b *Backoffer) longestSleepCfg() (*Config, int) {
 	}
 	return nil, 0
 }
+
+func (b *Backoffer) CheckKilled() error {
+	if b.vars != nil && b.vars.Killed != nil {
+		killed := atomic.LoadUint32(b.vars.Killed)
+		if killed != 0 {
+			logutil.BgLogger().Info(
+				"backoff stops because a killed signal is received",
+				zap.Uint32("signal", killed),
+			)
+			return errors.WithStack(tikverr.ErrQueryInterruptedWithSignal{Signal: killed})
+		}
+	}
+	return nil
+}

kv/variables.go

@@ -44,6 +44,10 @@ type Variables struct {
 
 	// Pointer to SessionVars.Killed
 	// Killed is a flag to indicate that this query is killed.
+	// This is an enum value rather than a boolean. See sqlkiller.go
+	// in TiDB for its definition.
+	// When its value is 0, it's not killed
+	// When its value is not 0, it's killed, the value indicates concrete reason.
 	Killed *uint32
 }
 

txnkv/transaction/2pc.go

@@ -1048,7 +1048,27 @@ func (c *twoPhaseCommitter) doActionOnGroupMutations(bo *retry.Backoffer, action
 }
 
 // doActionOnBatches does action to batches in parallel.
-func (c *twoPhaseCommitter) doActionOnBatches(bo *retry.Backoffer, action twoPhaseCommitAction, batches []batchMutations) error {
+func (c *twoPhaseCommitter) doActionOnBatches(
+	bo *retry.Backoffer, action twoPhaseCommitAction,
+	batches []batchMutations,
+) error {
+	// killSignal should never be nil for TiDB
+	if c.txn != nil && c.txn.vars != nil && c.txn.vars.Killed != nil {
+		// Do not reset the killed flag here. Let the upper layer reset the flag.
+		// Before it resets, any request is considered valid to be killed.
+		status := atomic.LoadUint32(c.txn.vars.Killed)
+		if status != 0 {
+			logutil.BgLogger().Info(
+				"query is killed", zap.Uint32(
+					"signal",
+					status,
+				),
+			)
+			// TODO: There might be various signals besides a query interruption,
+			// but we are unable to differentiate them, because the definition is in TiDB.
+			return errors.WithStack(tikverr.ErrQueryInterruptedWithSignal{Signal: status})
+		}
+	}
 	if len(batches) == 0 {
 		return nil
 	}