From 2420c1f03bba2c90d2406e486974cdc0c8af0cea Mon Sep 17 00:00:00 2001
From: AnandkumarPatel <anandkumarpatel@gmail.com>
Date: Wed, 25 Feb 2015 10:27:32 -0800
Subject: [PATCH] Add cacheBusted flag which gets set on the first cache miss
 Refactor of probeCache function

Signed-off-by: AnandkumarPatel <anandkumarpatel@gmail.com>
---
 builder/evaluator.go |  1 +
 builder/internals.go | 31 +++++++++++++++++--------------
 2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/builder/evaluator.go b/builder/evaluator.go
index 3ce5f0926f..eaf3f50697 100644
--- a/builder/evaluator.go
+++ b/builder/evaluator.go
@@ -90,6 +90,7 @@ type Builder struct {
 
 	Verbose      bool
 	UtilizeCache bool
+	cacheBusted  bool
 
 	// controls how images and containers are handled between steps.
 	Remove      bool
diff --git a/builder/internals.go b/builder/internals.go
index 54e2fe3bea..e554fd3026 100644
--- a/builder/internals.go
+++ b/builder/internals.go
@@ -502,21 +502,24 @@ func (b *Builder) processImageFrom(img *imagepkg.Image) error {
 // `(true, nil)`. If no image is found, it returns `(false, nil)`. If there
 // is any error, it returns `(false, err)`.
 func (b *Builder) probeCache() (bool, error) {
-	if b.UtilizeCache {
-		if cache, err := b.Daemon.ImageGetCached(b.image, b.Config); err != nil {
-			return false, err
-		} else if cache != nil {
-			fmt.Fprintf(b.OutStream, " ---> Using cache\n")
-			log.Debugf("[BUILDER] Use cached version")
-			b.image = cache.ID
-			return true, nil
-		} else {
-			log.Debugf("[BUILDER] Cache miss")
-			// after a miss we no longer need to probe
-			b.UtilizeCache = false
-		}
+	if !b.UtilizeCache || b.cacheBusted {
+		return false, nil
 	}
-	return false, nil
+
+	cache, err := b.Daemon.ImageGetCached(b.image, b.Config)
+	if err != nil {
+		return false, err
+	}
+	if cache == nil {
+		log.Debugf("[BUILDER] Cache miss")
+		b.cacheBusted = true
+		return false, nil
+	}
+
+	fmt.Fprintf(b.OutStream, " ---> Using cache\n")
+	log.Debugf("[BUILDER] Use cached version")
+	b.image = cache.ID
+	return true, nil
 }
 
 func (b *Builder) create() (*daemon.Container, error) {