Final changes to circular buffer

storage/memory/memory.go

@@ -15,7 +15,6 @@
 package memory
 
 import (
-	"container/list"
 	"fmt"
 	"sync"
 
@@ -27,7 +26,7 @@ import (
 // containerStorage is used to store per-container information
 type containerStorage struct {
 	ref         info.ContainerReference
-	recentStats *list.List
+	recentStats *StatsBuffer
 	maxNumStats int
 	lock        sync.RWMutex
 }
@@ -37,46 +36,32 @@ func (self *containerStorage) AddStats(stats *info.ContainerStats) error {
 	defer self.lock.Unlock()
 
 	// Add the stat to storage.
-	if self.recentStats.Len() >= self.maxNumStats {
-		self.recentStats.Remove(self.recentStats.Back())
-	}
-	self.recentStats.PushFront(stats)
+	self.recentStats.Add(stats)
 	return nil
 }
 
 func (self *containerStorage) RecentStats(numStats int) ([]*info.ContainerStats, error) {
 	self.lock.RLock()
 	defer self.lock.RUnlock()
-	if self.recentStats.Len() < numStats || numStats < 0 {
-		numStats = self.recentStats.Len()
+	if self.recentStats.Size() < numStats || numStats < 0 {
+		numStats = self.recentStats.Size()
 	}
 
 	// Stats in the recentStats list are stored in reverse chronological
 	// order, i.e. most recent stats is in the front.
-	// numStats will always <= recentStats.Len() so that there will be
+	// numStats will always <= recentStats.Size() so that there will be
 	// always at least numStats available stats to retrieve. We traverse
-	// the recentStats list from its head and fill the ret slice in
-	// reverse order so that the returned slice will be in chronological
+	// the recentStats list from its head so that the returned slice will be in chronological
 	// order. The order of the returned slice is not specified by the
 	// StorageDriver interface, so it is not necessary for other storage
 	// drivers to return the slice in the same order.
-	ret := make([]*info.ContainerStats, numStats)
-	e := self.recentStats.Front()
-	for i := numStats - 1; i >= 0; i-- {
-		data, ok := e.Value.(*info.ContainerStats)
-		if !ok {
-			return nil, fmt.Errorf("The %vth element is not a ContainerStats", i)
-		}
-		ret[i] = data
-		e = e.Next()
-	}
-	return ret, nil
+	return self.recentStats.FirstN(numStats), nil
 }
 
 func newContainerStore(ref info.ContainerReference, maxNumStats int) *containerStorage {
 	return &containerStorage{
 		ref:         ref,
-		recentStats: list.New(),
+		recentStats: NewStatsBuffer(maxNumStats),
 		maxNumStats: maxNumStats,
 	}
 }

storage/memory/stats_buffer.go

@@ -30,7 +30,7 @@ func (self *StatsBuffer) Add(item *info.ContainerStats) {
 }
 
 // Returns the first N elements in the buffer. If N > size of buffer, size of buffer elements are returned.
-func (self *StatsBuffer) FirstN(n int) []info.ContainerStats {
+func (self *StatsBuffer) FirstN(n int) []*info.ContainerStats {
 	// Cap n at the number of elements we have.
 	if n > self.size {
 		n = self.size
@@ -43,10 +43,10 @@ func (self *StatsBuffer) FirstN(n int) []info.ContainerStats {
 	}
 
 	// Copy the elements.
-	res := make([]info.ContainerStats, n)
+	res := make([]*info.ContainerStats, n)
 	for i := 0; i < n; i++ {
 		index := (start + i) % len(self.buffer)
-		res[i] = self.buffer[index]
+		res[i] = &self.buffer[index]
 	}
 	return res
 }

storage/memory/stats_buffer_test.go

@@ -4,6 +4,7 @@ import (
 	"testing"
 
 	"github.com/google/cadvisor/info"
+
 )
 
 func createStats(id int32) *info.ContainerStats {