polish use txn file

Signed-off-by: Ping Yu <[email protected]>

Author: pingyu

kv/variables.go

@@ -50,11 +50,8 @@ type Variables struct {
 	// When its value is not 0, it's killed, the value indicates concrete reason.
 	Killed *uint32
 
-	// TxnFileMinMutationSize specifies the minimum size of mutations to use file-based txn.
-	// <0: disabled.
-	// 0: use defalut value specified by config item TiKVClient.TxnFileMinMutationSize.
-	// >0: use the specified value.
-	TxnFileMinMutationSize int64
+	// EnableTxnFile specifies whether file-based txn is enabled.
+	EnableTxnFile bool
 }
 
 // NewVariables create a new Variables instance with default values.
@@ -63,6 +60,7 @@ func NewVariables(killed *uint32) *Variables {
 		BackoffLockFast: DefBackoffLockFast,
 		BackOffWeight:   DefBackOffWeight,
 		Killed:          killed,
+		EnableTxnFile:   true,
 	}
 }
 

txnkv/transaction/txn_file.go

@@ -807,17 +807,16 @@ func (c *twoPhaseCommitter) buildTxnFiles(bo *retry.Backoffer, mutations Committ
 }
 
 func (c *twoPhaseCommitter) useTxnFile() bool {
-	if c.txn == nil || c.txn.isPessimistic || c.txn.isInternal() ||
-		c.txn.vars.TxnFileMinMutationSize < 0 {
+	if c.txn == nil || !c.txn.vars.EnableTxnFile {
 		return false
 	}
 	conf := config.GetGlobalConfig()
-	minMutationSize := uint64(c.txn.vars.TxnFileMinMutationSize)
-	if minMutationSize == 0 {
-		minMutationSize = conf.TiKVClient.TxnFileMinMutationSize
-	}
-	return len(conf.TiKVClient.TxnChunkWriterAddr) > 0 &&
-		uint64(c.txn.GetMemBuffer().Size()) >= minMutationSize
+	// Don't use txn file for internal request to avoid affect system tables or metadata before it is stable enough.
+	// TODO: use txn file for internal TTL & DDL tasks.
+	return !c.txn.isPessimistic &&
+		!c.txn.isInternal() &&
+		len(conf.TiKVClient.TxnChunkWriterAddr) > 0 &&
+		uint64(c.txn.GetMemBuffer().Size()) >= conf.TiKVClient.TxnFileMinMutationSize
 }
 
 func (c *twoPhaseCommitter) preSplitTxnFileRegions(bo *retry.Backoffer) error {