Use monotonic time in lease #6888

fanminshi · 2016-11-22T00:08:18Z

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

gyuho · 2016-11-22T00:23:04Z

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


Is there anyway that we can enabled CGO only for darwin?
Maybe detect architecture in build script or make it configurable.

Linux still works fine with CGO disabled, as far as I know.

Yes. Try if [[ "$OSTYPE" == "darwin"* ]]; then

xiang90 · 2016-11-23T18:43:42Z

lease/lessor.go

@@ -22,6 +22,7 @@ import (
 	"sync"
 	"time"

+	"github.com/ScaleFT/monotime"


let's put a space between external dependency and internal dependency (coreos/etcd/xxx)

xiang90 · 2016-11-23T18:45:09Z

@fanminshi The author suggests us to use https://github.com/aristanetworks/goarista/blob/master/monotime/nanotime.go instead of his library.

fanminshi · 2016-11-23T19:09:51Z

@xiang90 the library that the author suggested imports unsafe. Not sure if that will cause a problem.
@heyitsanthony what do you think?

fanminshi · 2016-11-23T23:28:56Z

I sent a PR(ScaleFT/monotime#1) ScaleFT to use aristanetworks/goarista/monotime as source of monotime.

heyitsanthony · 2016-11-28T21:51:27Z

@fanminshi the scaleft package already imports unsafe anyway. The vendoring for all the w32 stuff seems like overkill. Just pulling in nanotime() / using the arista library is probably better

fanminshi · 2016-11-28T22:48:32Z

@heyitsanthony the scaleft guy decides to use "golang.org/x/sys/windows" for windows part. ScaleFT/monotime#2

fanminshi · 2016-11-28T22:48:56Z

All fixed. PLTAL @xiang90 @xiang90 @heyitsanthony

heyitsanthony · 2016-11-28T22:51:42Z

@fanminshi vendor updates should be separate commits, but is there any reason not to use the arista code? The windows deps still seem excessive for what this does.

fanminshi · 2016-11-28T22:56:00Z

@heyitsanthony I'll make separate commits for vendored stuff. My original PR to scaleFT uses arista code for windows,ScaleFT/monotime#1. However, I think scaleFT guy decided to use "golang.org/x/sys/windows". In this case, if I want to use ScaleFT, I have to import the windows deps. is there a way to get around that. I could just use our own version of their code like https://github.com/fanminshi/monotime

fanminshi · 2016-11-29T00:41:05Z

All fixed. PTAL @xiang90 @heyitsanthony @gyuho

gyuho · 2016-11-29T00:43:28Z

pkg/monotime/monotime.go

+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package monotime


add blank line above? Otherwise it will break godoc?

I still see

+// See the License for the specific language governing permissions and +// limitations under the License. +package monotime

?

Can you double-check?

Thanks.

It should be

+// See the License for the specific language governing permissions and +// limitations under the License. + +package monotime

It's fixed now

gyuho · 2016-11-29T00:54:43Z

pkg/monotime/monotime.go

+	return Now()
+}
+
+func (t *monoTimer) Since(start uint64) time.Duration {


Why do we need separate Since method?

It seems to me Since() could be useful function. I could make it a private helper function.

not sure why this is a method on monoTimer since it doesn't use anything from monoTimer

Ok keeping it sounds good to me.

gyuho · 2016-11-29T18:21:23Z

pkg/monotime/nanotime_test.go

+// Use of this source code is governed by the Apache License 2.0
+// that can be found in the COPYING file.
+
+// Package monotime provides a fast monotonic clock source.


remove this comment

// that can be... package monotime

?

Will change

gyuho · 2016-11-29T18:21:40Z

lgtm. defer to @xiang90 @heyitsanthony

heyitsanthony · 2016-11-29T18:06:40Z

pkg/monotime/monotime.go

+	return Now()
+}
+
+func (t *monoTimer) Since(start uint64) time.Duration {


not sure why this is a method on monoTimer since it doesn't use anything from monoTimer

heyitsanthony · 2016-11-29T18:10:21Z

lease/lessor.go

-	// expiry time in unixnano
-	expiry  time.Time
+	// expiry is time when lease should expire
+	expiry  time.Duration


This is the wrong type; Durations aren't deadlines. Probably have a type monotime.Time uint64 (to indicate it's not a time based on the system time) or something?

heyitsanthony · 2016-11-29T18:11:40Z

pkg/monotime/monotime.go

+	"time"
+)
+
+type Timer interface {


I thought this interface wasn't going to be used? Why are monotime.Now() and monotime.Since(uint64) not good enough? I don't think wrapping Now/Since with this really buys anything

yeah, monotime.Now() and monotime.Since(uint64) should be sufficient. Will change to that

heyitsanthony · 2016-11-29T18:14:52Z

pkg/monotime/monotime.go

+	// Since returns duration between two points of time
+	Since(uint64) time.Duration
+	// SinceBegining returns duration between now and when timer is created
+	SinceBegining() time.Duration


heyitsanthony · 2016-11-29T18:22:31Z

lease/lessor.go

-	forever = time.Unix(math.MaxInt64>>1, 0)
+
+	monoTimer = monotime.New()
+	forever   = time.Duration(1>>63 - 1)


math.MaxInt64

fanminshi · 2016-11-29T19:53:43Z

All fixed. PTAL @heyitsanthony @gyuho

xiang90 · 2016-11-29T20:15:36Z

@fanminshi

CI fails with

pkg/monotime/monotime.go.21: // time represents a point in monotonic time (godoc-export: time -> Time?)

gyuho · 2016-11-29T20:18:49Z

pkg/monotime/monotime.go

+	"time"
+)
+
+// time represents a point in monotonic time


Yeah let's change this to Time... go vet complains

yeah, I just changed that.

gyuho · 2016-11-29T20:26:46Z

pkg/monotime/nanotime.go

+// Use of this source code is governed by the Apache License 2.0
+// that can be found in the COPYING file.
+
+// Package monotime provides a fast monotonic clock source.


This should be

// Package monotime provides a fast monotonic clock source. package monotime

Otherwise godoc won't catch it.

gyuho · 2016-11-29T20:27:03Z

pkg/monotime/nanotime_test.go

+// Copyright (C) 2016  Arista Networks, Inc.
+// Use of this source code is governed by the Apache License 2.0
+
+// Package monotime provides a fast monotonic clock source.


And this description is duplicate?

will remove

lease uses monotimer to calculate its expiration. In this way, changing system time won't affect in lease expiration. FIX etcd-io#6700

fanminshi · 2016-11-29T20:36:29Z

All fixed. PTAL @xiang90 @heyitsanthony @gyuho

heyitsanthony · 2016-11-29T20:51:34Z

lgtm

fanminshi added the type/bug label Nov 22, 2016

gyuho reviewed Nov 22, 2016

View reviewed changes

fanminshi added the WIP label Nov 22, 2016

fanminshi force-pushed the use_monotonic_time_for_lease branch from 152dcdb to 86f0bfd Compare November 22, 2016 01:19

xiang90 reviewed Nov 23, 2016

View reviewed changes

fanminshi force-pushed the use_monotonic_time_for_lease branch from 86f0bfd to 7d30c8a Compare November 23, 2016 19:13

fanminshi force-pushed the use_monotonic_time_for_lease branch 2 times, most recently from 3db0b96 to e99e48a Compare November 28, 2016 22:40

fanminshi force-pushed the use_monotonic_time_for_lease branch 2 times, most recently from 2968469 to 584b431 Compare November 29, 2016 00:30

fanminshi removed the WIP label Nov 29, 2016

fanminshi force-pushed the use_monotonic_time_for_lease branch 4 times, most recently from 37260f6 to 20841b7 Compare November 29, 2016 00:40