lease: use monotimer for lease

lease uses monotimer to calculate its expiration. In this way, changing system time won't affect in lease expiration.

FIX #6700

build

@@ -35,8 +35,8 @@ etcd_build() {
 	if [ -n "${BINDIR}" ]; then out="${BINDIR}"; fi
 	toggle_failpoints
 	# Static compilation is useful when etcd is run in a container
-	CGO_ENABLED=0 go build $GO_BUILD_FLAGS -installsuffix cgo -ldflags "$GO_LDFLAGS" -o ${out}/etcd ${REPO_PATH}/cmd/etcd || return
-	CGO_ENABLED=0 go build $GO_BUILD_FLAGS -installsuffix cgo -ldflags "$GO_LDFLAGS" -o ${out}/etcdctl ${REPO_PATH}/cmd/etcdctl || return
+	go build $GO_BUILD_FLAGS -installsuffix cgo -ldflags "$GO_LDFLAGS" -o ${out}/etcd ${REPO_PATH}/cmd/etcd || return
+	go build $GO_BUILD_FLAGS -installsuffix cgo -ldflags "$GO_LDFLAGS" -o ${out}/etcdctl ${REPO_PATH}/cmd/etcdctl || return
 }
 
 etcd_setup_gopath() {

lease/lessor.go

@@ -22,6 +22,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ScaleFT/monotime"
+
 	"github.com/coreos/etcd/lease/leasepb"
 	"github.com/coreos/etcd/mvcc/backend"
 )
@@ -33,9 +35,9 @@ const (
 
 var (
 	leaseBucketName = []byte("lease")
-	// do not use maxInt64 since it can overflow time which will add
-	// the offset of unix time (1970yr to seconds).
-	forever = time.Unix(math.MaxInt64>>1, 0)
+
+	monoTimer = monotime.New()
+	forever   = time.Duration(1>>63 - 1)
 
 	ErrNotPrimary    = errors.New("not a primary lessor")
 	ErrLeaseNotFound = errors.New("lease not found")
@@ -504,8 +506,8 @@ type Lease struct {
 	ttl int64 // time to live in seconds
 
 	itemSet map[LeaseItem]struct{}
-	// expiry time in unixnano
-	expiry  time.Time
+	// expiry is time when lease should expire
+	expiry  time.Duration
 	revokec chan struct{}
 }
 
@@ -534,7 +536,7 @@ func (l *Lease) TTL() int64 {
 
 // refresh refreshes the expiry of the lease.
 func (l *Lease) refresh(extend time.Duration) {
-	l.expiry = time.Now().Add(extend + time.Second*time.Duration(l.ttl))
+	l.expiry = extend + monoTimer.Elapsed() + time.Duration(l.ttl)*time.Second
 }
 
 // forever sets the expiry of lease to be forever.
@@ -551,7 +553,7 @@ func (l *Lease) Keys() []string {
 
 // Remaining returns the remaining time of the lease.
 func (l *Lease) Remaining() time.Duration {
-	return l.expiry.Sub(time.Now())
+	return l.expiry - monoTimer.Elapsed()
 }
 
 type LeaseItem struct {

lease/lessor_test.go

@@ -26,7 +26,10 @@ import (
 	"github.com/coreos/etcd/mvcc/backend"
 )
 
-const minLeaseTTL = int64(5)
+const (
+	minLeaseTTL         = int64(5)
+	minLeaseTTLDuration = time.Duration(minLeaseTTL) * time.Second
+)
 
 // TestLessorGrant ensures Lessor can grant wanted lease.
 // The granted lease should have a unique ID with a term
@@ -48,8 +51,9 @@ func TestLessorGrant(t *testing.T) {
 	if !reflect.DeepEqual(gl, l) {
 		t.Errorf("lease = %v, want %v", gl, l)
 	}
-	if l.expiry.Sub(time.Now()) < time.Duration(minLeaseTTL)*time.Second-time.Second {
-		t.Errorf("term = %v, want at least %v", l.expiry.Sub(time.Now()), time.Duration(minLeaseTTL)*time.Second-time.Second)
+	minLeaseTTLDura
+	if l.Remaining() < minLeaseTTLDuration-time.Second {
+		t.Errorf("term = %v, want at least %v", l.Remaining(), minLeaseTTLDuration-time.Second)
 	}
 
 	nl, err := le.Grant(1, 1)
@@ -152,7 +156,7 @@ func TestLessorRenew(t *testing.T) {
 	}
 
 	l = le.Lookup(l.ID)
-	if l.expiry.Sub(time.Now()) < 9*time.Second {
+	if l.Remaining() < 9*time.Second {
 		t.Errorf("failed to renew the lease")
 	}
 }