From ec3ca84ad92645d60ecb92fb79cf7726e589748a Mon Sep 17 00:00:00 2001
From: Tejal Desai <tejal29@gmail.com>
Date: Thu, 4 Jun 2020 22:02:13 -0700
Subject: [PATCH] add another redo snapshotter

---
 Makefile                   |  4 ++--
 pkg/constants/constants.go |  1 +
 pkg/executor/build.go      | 11 +++++++----
 pkg/util/util.go           | 22 ++++++++++++++++++++++
 4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 0966fe693..1d2e4aeb7 100644
--- a/Makefile
+++ b/Makefile
@@ -88,8 +88,8 @@ integration-test-misc:
 
 .PHONY: images
 images:
-	docker build ${BUILD_ARG} --build-arg=GOARCH=$(GOARCH) -t $(REGISTRY)/executor:latest -f deploy/Dockerfile .
-	docker build ${BUILD_ARG} --build-arg=GOARCH=$(GOARCH) -t $(REGISTRY)/executor:debug -f deploy/Dockerfile_debug .
+	docker build ${BUILD_ARG} --build-arg=GOARCH=$(GOARCH) -t $(REGISTRY)/executor:perf-latest -f deploy/Dockerfile .
+	docker build ${BUILD_ARG} --build-arg=GOARCH=$(GOARCH) -t $(REGISTRY)/executor:perf-debug -f deploy/Dockerfile_debug .
 	docker build ${BUILD_ARG} --build-arg=GOARCH=$(GOARCH) -t $(REGISTRY)/warmer:latest -f deploy/Dockerfile_warmer .
 
 .PHONY: push
diff --git a/pkg/constants/constants.go b/pkg/constants/constants.go
index aaa0c815a..0d6ddc9f5 100644
--- a/pkg/constants/constants.go
+++ b/pkg/constants/constants.go
@@ -47,6 +47,7 @@ const (
 	// Various snapshot modes:
 	SnapshotModeTime = "time"
 	SnapshotModeFull = "full"
+	SnapshotModeRedo = "redo"
 
 	// NoBaseImage is the scratch image
 	NoBaseImage = "scratch"
diff --git a/pkg/executor/build.go b/pkg/executor/build.go
index d05ddecaa..87c8cad43 100644
--- a/pkg/executor/build.go
+++ b/pkg/executor/build.go
@@ -808,14 +808,17 @@ func saveStageAsTarball(path string, image v1.Image) error {
 }
 
 func getHasher(snapshotMode string) (func(string) (string, error), error) {
-	if snapshotMode == constants.SnapshotModeTime {
+	switch snapshotMode {
+	case constants.SnapshotModeTime:
 		logrus.Info("Only file modification time will be considered when snapshotting")
 		return util.MtimeHasher(), nil
-	}
-	if snapshotMode == constants.SnapshotModeFull {
+	case constants.SnapshotModeFull:
 		return util.Hasher(), nil
+	case constants.SnapshotModeRedo:
+		return util.RedoHasher(), nil
+	default:
+		return nil, fmt.Errorf("%s is not a valid snapshot mode", snapshotMode)
 	}
-	return nil, fmt.Errorf("%s is not a valid snapshot mode", snapshotMode)
 }
 
 func resolveOnBuild(stage *config.KanikoStage, config *v1.Config, stageNameToIdx map[string]string) error {
diff --git a/pkg/util/util.go b/pkg/util/util.go
index a1dd77f4f..72fac9df5 100644
--- a/pkg/util/util.go
+++ b/pkg/util/util.go
@@ -115,6 +115,28 @@ func MtimeHasher() func(string) (string, error) {
 	return hasher
 }
 
+// RedoHasher returns a hash function, which looks at mtime, size, filemode, owner uid and gid
+// Note that the mtime can lag, so it's possible that a file will have changed but the mtime may look the same.
+func RedoHasher() func(string) (string, error) {
+	hasher := func(p string) (string, error) {
+		h := md5.New()
+		fi, err := os.Lstat(p)
+		if err != nil {
+			return "", err
+		}
+		h.Write([]byte(fi.Mode().String()))
+		h.Write([]byte(fi.ModTime().String()))
+		h.Write([]byte(strconv.FormatInt(fi.Size(), 64)))
+		h.Write([]byte(strconv.FormatUint(uint64(fi.Sys().(*syscall.Stat_t).Uid), 36)))
+		h.Write([]byte(","))
+		h.Write([]byte(strconv.FormatUint(uint64(fi.Sys().(*syscall.Stat_t).Gid), 36)))
+
+		return hex.EncodeToString(h.Sum(nil)), nil
+	}
+	return hasher
+}
+
+
 // SHA256 returns the shasum of the contents of r
 func SHA256(r io.Reader) (string, error) {
 	hasher := sha256.New()