From 94d812749cc652391031e67129b2764a7668fdf6 Mon Sep 17 00:00:00 2001
From: crazycs <crazycs520@gmail.com>
Date: Thu, 27 Jun 2019 20:04:22 +0800
Subject: [PATCH] add check for gc life time too small (#10936) (#10951)

---
 store/tikv/gcworker/gc_worker.go      | 27 +++++++++++++++++++++
 store/tikv/gcworker/gc_worker_test.go | 35 +++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/store/tikv/gcworker/gc_worker.go b/store/tikv/gcworker/gc_worker.go
index c6fc712804655..24050a6aa6e29 100644
--- a/store/tikv/gcworker/gc_worker.go
+++ b/store/tikv/gcworker/gc_worker.go
@@ -30,6 +30,7 @@ import (
 	"github.com/pingcap/kvproto/pkg/metapb"
 	"github.com/pingcap/parser/terror"
 	"github.com/pingcap/pd/client"
+	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/ddl/util"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/meta"
@@ -114,6 +115,7 @@ const (
 
 	gcLifeTimeKey        = "tikv_gc_life_time"
 	gcDefaultLifeTime    = time.Minute * 10
+	gcMinLifeTime        = time.Minute * 10
 	gcSafePointKey       = "tikv_gc_safe_point"
 	gcConcurrencyKey     = "tikv_gc_concurrency"
 	gcDefaultConcurrency = 2
@@ -436,11 +438,36 @@ func (w *GCWorker) checkGCInterval(now time.Time) (bool, error) {
 	return true, nil
 }
 
+// validateGCLiftTime checks whether life time is small than min gc life time.
+func (w *GCWorker) validateGCLiftTime(lifeTime time.Duration) (time.Duration, error) {
+	minLifeTime := gcMinLifeTime
+	// max-txn-time-use value is less than gc_life_time - 10s.
+	maxTxnTime := time.Duration(config.GetGlobalConfig().TiKVClient.MaxTxnTimeUse+10) * time.Second
+	if minLifeTime < maxTxnTime {
+		minLifeTime = maxTxnTime
+	}
+
+	if lifeTime >= minLifeTime {
+		return lifeTime, nil
+	}
+
+	logutil.Logger(context.Background()).Info("[gc worker] invalid gc life time",
+		zap.Duration("get gc life time", lifeTime),
+		zap.Duration("min gc life time", minLifeTime))
+
+	err := w.saveDuration(gcLifeTimeKey, minLifeTime)
+	return minLifeTime, err
+}
+
 func (w *GCWorker) calculateNewSafePoint(now time.Time) (*time.Time, error) {
 	lifeTime, err := w.loadDurationWithDefault(gcLifeTimeKey, gcDefaultLifeTime)
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
+	*lifeTime, err = w.validateGCLiftTime(*lifeTime)
+	if err != nil {
+		return nil, err
+	}
 	metrics.GCConfigGauge.WithLabelValues(gcLifeTimeKey).Set(lifeTime.Seconds())
 	lastSafePoint, err := w.loadTime(gcSafePointKey)
 	if err != nil {
diff --git a/store/tikv/gcworker/gc_worker_test.go b/store/tikv/gcworker/gc_worker_test.go
index 58b1b5cea08b3..357ae13bcdfe0 100644
--- a/store/tikv/gcworker/gc_worker_test.go
+++ b/store/tikv/gcworker/gc_worker_test.go
@@ -23,6 +23,7 @@ import (
 	. "github.com/pingcap/check"
 	"github.com/pingcap/failpoint"
 	"github.com/pingcap/kvproto/pkg/errorpb"
+	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/domain"
 	"github.com/pingcap/tidb/session"
 	"github.com/pingcap/tidb/store/mockoracle"
@@ -166,6 +167,40 @@ func (s *testGCWorkerSuite) TestPrepareGC(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(ok, IsTrue)
 
+	// Check gc life time small than min.
+	s.oracle.AddOffset(time.Minute * 40)
+	err = s.gcWorker.saveDuration(gcLifeTimeKey, time.Minute)
+	c.Assert(err, IsNil)
+	ok, _, err = s.gcWorker.prepare()
+	c.Assert(err, IsNil)
+	c.Assert(ok, IsTrue)
+	lifeTime, err := s.gcWorker.loadDuration(gcLifeTimeKey)
+	c.Assert(err, IsNil)
+	c.Assert(*lifeTime, Equals, gcMinLifeTime)
+
+	// Check gc life time small than config.max-txn-use-time
+	s.oracle.AddOffset(time.Minute * 40)
+	config.GetGlobalConfig().TiKVClient.MaxTxnTimeUse = 20*60 - 10 // 20min - 10s
+	err = s.gcWorker.saveDuration(gcLifeTimeKey, time.Minute)
+	c.Assert(err, IsNil)
+	ok, _, err = s.gcWorker.prepare()
+	c.Assert(err, IsNil)
+	c.Assert(ok, IsTrue)
+	lifeTime, err = s.gcWorker.loadDuration(gcLifeTimeKey)
+	c.Assert(err, IsNil)
+	c.Assert(*lifeTime, Equals, 20*time.Minute)
+
+	// check the tikv_gc_life_time more than config.max-txn-use-time situation.
+	s.oracle.AddOffset(time.Minute * 40)
+	err = s.gcWorker.saveDuration(gcLifeTimeKey, time.Minute*30)
+	c.Assert(err, IsNil)
+	ok, _, err = s.gcWorker.prepare()
+	c.Assert(err, IsNil)
+	c.Assert(ok, IsTrue)
+	lifeTime, err = s.gcWorker.loadDuration(gcLifeTimeKey)
+	c.Assert(err, IsNil)
+	c.Assert(*lifeTime, Equals, 30*time.Minute)
+
 	// Change auto concurrency
 	err = s.gcWorker.saveValueToSysTable(gcAutoConcurrencyKey, booleanFalse)
 	c.Assert(err, IsNil)