Update cadvisor version to latest version

vendor/github.com/google/cadvisor/zfs/watcher.go

@@ -0,0 +1,113 @@
+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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 zfs
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/golang/glog"
+	zfs "github.com/mistifyio/go-zfs"
+)
+
+// zfsWatcher maintains a cache of filesystem -> usage stats for a
+// zfs filesystem
+type ZfsWatcher struct {
+	filesystem string
+	lock       *sync.RWMutex
+	cache      map[string]uint64
+	period     time.Duration
+	stopChan   chan struct{}
+}
+
+// NewThinPoolWatcher returns a new ThinPoolWatcher for the given devicemapper
+// thin pool name and metadata device or an error.
+func NewZfsWatcher(filesystem string) (*ZfsWatcher, error) {
+
+	return &ZfsWatcher{
+		filesystem: filesystem,
+		lock:       &sync.RWMutex{},
+		cache:      make(map[string]uint64),
+		period:     15 * time.Second,
+		stopChan:   make(chan struct{}),
+	}, nil
+}
+
+// Start starts the ZfsWatcher.
+func (w *ZfsWatcher) Start() {
+	err := w.Refresh()
+	if err != nil {
+		glog.Errorf("encountered error refreshing zfs watcher: %v", err)
+	}
+
+	for {
+		select {
+		case <-w.stopChan:
+			return
+		case <-time.After(w.period):
+			start := time.Now()
+			err = w.Refresh()
+			if err != nil {
+				glog.Errorf("encountered error refreshing zfs watcher: %v", err)
+			}
+
+			// print latency for refresh
+			duration := time.Since(start)
+			glog.V(5).Infof("zfs(%d) took %s", start.Unix(), duration)
+		}
+	}
+}
+
+// Stop stops the ZfsWatcher.
+func (w *ZfsWatcher) Stop() {
+	close(w.stopChan)
+}
+
+// GetUsage gets the cached usage value of the given filesystem.
+func (w *ZfsWatcher) GetUsage(filesystem string) (uint64, error) {
+	w.lock.RLock()
+	defer w.lock.RUnlock()
+
+	v, ok := w.cache[filesystem]
+	if !ok {
+		return 0, fmt.Errorf("no cached value for usage of filesystem %v", filesystem)
+	}
+
+	return v, nil
+}
+
+// Refresh performs a zfs get
+func (w *ZfsWatcher) Refresh() error {
+	w.lock.Lock()
+	defer w.lock.Unlock()
+	newCache := make(map[string]uint64)
+	parent, err := zfs.GetDataset(w.filesystem)
+	if err != nil {
+		glog.Errorf("encountered error getting zfs filesystem: %s: %v", w.filesystem, err)
+		return err
+	}
+	children, err := parent.Children(0)
+	if err != nil {
+		glog.Errorf("encountered error getting children of zfs filesystem: %s: %v", w.filesystem, err)
+		return err
+	}
+
+	for _, ds := range children {
+		newCache[ds.Name] = ds.Used
+	}
+
+	w.cache = newCache
+	return nil
+}