region_request: remove backoff for stale read (tikv#1423) (tikv#1427)

* remove stale read backoff



* sort imports



---------

Signed-off-by: you06 <[email protected]>

Author: you06

config/retry/backoff_test.go

@@ -57,7 +57,7 @@ func TestBackoffErrorType(t *testing.T) {
 	assert.Nil(t, err)
 	// 6ms sleep at most in total
 	for i := 0; i < 2; i++ {
-		err = b.Backoff(BoMaxDataNotReady, errors.New("data not ready"))
+		err = b.Backoff(BoMaxRegionNotInitialized, errors.New("region not initialized"))
 		assert.Nil(t, err)
 	}
 	// 100ms sleep at most in total
@@ -88,15 +88,15 @@ func TestBackoffDeepCopy(t *testing.T) {
 	b := NewBackofferWithVars(context.TODO(), 4, nil)
 	// 700 ms sleep in total and the backoffer will return an error next time.
 	for i := 0; i < 3; i++ {
-		err = b.Backoff(BoMaxDataNotReady, errors.New("data not ready"))
+		err = b.Backoff(BoMaxRegionNotInitialized, errors.New("region not initialized"))
 		assert.Nil(t, err)
 	}
 	bForked, cancel := b.Fork()
 	defer cancel()
 	bCloned := b.Clone()
 	for _, b := range []*Backoffer{bForked, bCloned} {
 		err = b.Backoff(BoTiKVRPC, errors.New("tikv rpc"))
-		assert.ErrorIs(t, err, BoMaxDataNotReady.err)
+		assert.ErrorIs(t, err, BoMaxRegionNotInitialized.err)
 	}
 }
 

config/retry/config.go

@@ -133,7 +133,6 @@ var (
 	BoTxnNotFound              = NewConfig("txnNotFound", &metrics.BackoffHistogramEmpty, NewBackoffFnCfg(2, 500, NoJitter), tikverr.ErrResolveLockTimeout)
 	BoStaleCmd                 = NewConfig("staleCommand", &metrics.BackoffHistogramStaleCmd, NewBackoffFnCfg(2, 1000, NoJitter), tikverr.ErrTiKVStaleCommand)
 	BoMaxTsNotSynced           = NewConfig("maxTsNotSynced", &metrics.BackoffHistogramEmpty, NewBackoffFnCfg(2, 500, NoJitter), tikverr.ErrTiKVMaxTimestampNotSynced)
-	BoMaxDataNotReady          = NewConfig("dataNotReady", &metrics.BackoffHistogramDataNotReady, NewBackoffFnCfg(2, 2000, NoJitter), tikverr.ErrRegionDataNotReady)
 	BoMaxRegionNotInitialized  = NewConfig("regionNotInitialized", &metrics.BackoffHistogramEmpty, NewBackoffFnCfg(2, 1000, NoJitter), tikverr.ErrRegionNotInitialized)
 	BoIsWitness                = NewConfig("isWitness", &metrics.BackoffHistogramIsWitness, NewBackoffFnCfg(1000, 10000, EqualJitter), tikverr.ErrIsWitness)
 	// TxnLockFast's `base` load from vars.BackoffLockFast when create BackoffFn.

internal/locate/region_request.go

@@ -2647,13 +2647,7 @@ func (s *RegionRequestSender) onRegionError(
 		if s.replicaSelector != nil {
 			s.replicaSelector.onDataIsNotReady()
 		}
-		if !req.IsGlobalStaleRead() {
-			// only backoff local stale reads as global should retry immediately against the leader as a normal read
-			err = bo.Backoff(retry.BoMaxDataNotReady, errors.New("data is not ready"))
-			if err != nil {
-				return false, err
-			}
-		}
+		// do not backoff data-is-not-ready as we always retry with normal snapshot read.
 		return true, nil
 	}