From 8c4a1ef81d1011ac44780f80d3c395e30180f624 Mon Sep 17 00:00:00 2001
From: Nan Monnand Deng <monnand@gmail.com>
Date: Fri, 11 Jul 2014 17:21:28 -0400
Subject: [PATCH] Requires storage driver to return stats in time increasing
 order. Change influxdb driver to return stats in correct order.

---
 storage/influxdb/influxdb.go | 15 +++++++++++----
 storage/storage.go           |  4 +++-
 storage/test/storagetests.go | 24 ++++++++----------------
 3 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/storage/influxdb/influxdb.go b/storage/influxdb/influxdb.go
index 1fcb170f..99cb92c7 100644
--- a/storage/influxdb/influxdb.go
+++ b/storage/influxdb/influxdb.go
@@ -331,8 +331,13 @@ func (self *influxdbStorage) RecentStats(containerName string, numStats int) ([]
 		return nil, err
 	}
 	statsList := make([]*info.ContainerStats, 0, len(series))
-	for _, s := range series {
-		for _, values := range s.Points {
+	// By default, influxDB returns data in time descending order.
+	// RecentStats() requires stats in time increasing order,
+	// so we need to go through from the last one to the first one.
+	for i := len(series) - 1; i >= 0; i-- {
+		s := series[i]
+		for j := len(s.Points) - 1; j >= 0; j-- {
+			values := s.Points[j]
 			stats, err := self.valuesToContainerStats(s.Columns, values)
 			if err != nil {
 				return nil, err
@@ -358,8 +363,10 @@ func (self *influxdbStorage) Samples(containerName string, numSamples int) ([]*i
 		return nil, err
 	}
 	sampleList := make([]*info.ContainerStatsSample, 0, len(series))
-	for _, s := range series {
-		for _, values := range s.Points {
+	for i := len(series) - 1; i >= 0; i-- {
+		s := series[i]
+		for j := len(s.Points) - 1; j >= 0; j-- {
+			values := s.Points[j]
 			sample, err := self.valuesToContainerSample(s.Columns, values)
 			if err != nil {
 				return nil, err
diff --git a/storage/storage.go b/storage/storage.go
index 8b264a93..84ca0b3b 100644
--- a/storage/storage.go
+++ b/storage/storage.go
@@ -21,7 +21,9 @@ type StorageDriver interface {
 
 	// Read most recent stats. numStats indicates max number of stats
 	// returned. The returned stats must be consecutive observed stats. If
-	// numStats < 0, then return all stats stored in the storage.
+	// numStats < 0, then return all stats stored in the storage. The
+	// returned stats should be sorted in time increasing order, i.e. Most
+	// recent stats should be the last.
 	RecentStats(containerName string, numStats int) ([]*info.ContainerStats, error)
 
 	// Read the specified percentiles of CPU and memory usage of the container.
diff --git a/storage/test/storagetests.go b/storage/test/storagetests.go
index 99912032..8bad2c4d 100644
--- a/storage/test/storagetests.go
+++ b/storage/test/storagetests.go
@@ -392,14 +392,10 @@ func StorageDriverTestRetrievePartialRecentStats(driver storage.StorageDriver, t
 
 	actualRecentStats := trace[len(trace)-len(recentStats):]
 
-	for _, r := range recentStats {
-		found := false
-		for _, s := range actualRecentStats {
-			if statsEq(s, r) {
-				found = true
-			}
-		}
-		if !found {
+	// The returned stats should be sorted in time increasing order
+	for i, s := range actualRecentStats {
+		r := recentStats[i]
+		if !statsEq(s, r) {
 			t.Errorf("unexpected stats %+v with memory usage %v", r, r.Memory.Usage)
 		}
 	}
@@ -438,14 +434,10 @@ func StorageDriverTestRetrieveAllRecentStats(driver storage.StorageDriver, t *te
 
 	actualRecentStats := trace[len(trace)-len(recentStats):]
 
-	for _, r := range recentStats {
-		found := false
-		for _, s := range actualRecentStats {
-			if statsEq(s, r) {
-				found = true
-			}
-		}
-		if !found {
+	// The returned stats should be sorted in time increasing order
+	for i, s := range actualRecentStats {
+		r := recentStats[i]
+		if !statsEq(s, r) {
 			t.Errorf("unexpected stats %+v with memory usage %v", r, r.Memory.Usage)
 		}
 	}