github.com/google/cadvisor@v0.49.1/zfs/watcher.go (about)

     1  // Copyright 2016 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package zfs
    16  
    17  import (
    18  	"fmt"
    19  	"sync"
    20  	"time"
    21  
    22  	zfs "github.com/mistifyio/go-zfs"
    23  	"k8s.io/klog/v2"
    24  )
    25  
    26  // zfsWatcher maintains a cache of filesystem -> usage stats for a
    27  // zfs filesystem
    28  type ZfsWatcher struct {
    29  	filesystem string
    30  	lock       *sync.RWMutex
    31  	cache      map[string]uint64
    32  	period     time.Duration
    33  	stopChan   chan struct{}
    34  }
    35  
    36  // NewThinPoolWatcher returns a new ThinPoolWatcher for the given devicemapper
    37  // thin pool name and metadata device or an error.
    38  func NewZfsWatcher(filesystem string) (*ZfsWatcher, error) {
    39  
    40  	return &ZfsWatcher{
    41  		filesystem: filesystem,
    42  		lock:       &sync.RWMutex{},
    43  		cache:      make(map[string]uint64),
    44  		period:     15 * time.Second,
    45  		stopChan:   make(chan struct{}),
    46  	}, nil
    47  }
    48  
    49  // Start starts the ZfsWatcher.
    50  func (w *ZfsWatcher) Start() {
    51  	err := w.Refresh()
    52  	if err != nil {
    53  		klog.Errorf("encountered error refreshing zfs watcher: %v", err)
    54  	}
    55  
    56  	for {
    57  		select {
    58  		case <-w.stopChan:
    59  			return
    60  		case <-time.After(w.period):
    61  			start := time.Now()
    62  			err = w.Refresh()
    63  			if err != nil {
    64  				klog.Errorf("encountered error refreshing zfs watcher: %v", err)
    65  			}
    66  
    67  			// print latency for refresh
    68  			duration := time.Since(start)
    69  			klog.V(5).Infof("zfs(%d) took %s", start.Unix(), duration)
    70  		}
    71  	}
    72  }
    73  
    74  // Stop stops the ZfsWatcher.
    75  func (w *ZfsWatcher) Stop() {
    76  	close(w.stopChan)
    77  }
    78  
    79  // GetUsage gets the cached usage value of the given filesystem.
    80  func (w *ZfsWatcher) GetUsage(filesystem string) (uint64, error) {
    81  	w.lock.RLock()
    82  	defer w.lock.RUnlock()
    83  
    84  	v, ok := w.cache[filesystem]
    85  	if !ok {
    86  		return 0, fmt.Errorf("no cached value for usage of filesystem %v", filesystem)
    87  	}
    88  
    89  	return v, nil
    90  }
    91  
    92  // Refresh performs a zfs get
    93  func (w *ZfsWatcher) Refresh() error {
    94  	w.lock.Lock()
    95  	defer w.lock.Unlock()
    96  	newCache := make(map[string]uint64)
    97  	parent, err := zfs.GetDataset(w.filesystem)
    98  	if err != nil {
    99  		klog.Errorf("encountered error getting zfs filesystem: %s: %v", w.filesystem, err)
   100  		return err
   101  	}
   102  	children, err := parent.Children(0)
   103  	if err != nil {
   104  		klog.Errorf("encountered error getting children of zfs filesystem: %s: %v", w.filesystem, err)
   105  		return err
   106  	}
   107  
   108  	for _, ds := range children {
   109  		newCache[ds.Name] = ds.Used
   110  	}
   111  
   112  	w.cache = newCache
   113  	return nil
   114  }