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Merge pull request #7559 from fgrzadkowski/perf

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Add a simple cache for objects stored in etcd.
This commit is contained in:
Clayton Coleman 2015-04-30 11:27:01 -04:00
commit e637cd66e8
5 changed files with 125 additions and 30 deletions
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3
pkg/master/master_test.go
View File

@ -31,7 +31,8 @@ func TestGetServersToValidate(t *testing.T) {
config := Config{}
fakeClient := tools.NewFakeEtcdClient(t)
fakeClient.Machines = []string{"http://machine1:4001", "http://machine2", "http://machine3:4003"}
config.EtcdHelper = tools.EtcdHelper{fakeClient, latest.Codec, nil, etcdtest.PathPrefix()}
config.EtcdHelper = tools.NewEtcdHelper(fakeClient, latest.Codec, etcdtest.PathPrefix())
config.EtcdHelper.Versioner = nil
master.nodeRegistry = registrytest.NewMinionRegistry([]string{"node1", "node2"}, api.NodeResources{})

84
pkg/tools/etcd_helper.go
View File

@ -26,6 +26,7 @@ import (
"path"
"reflect"
"strings"
"sync"
"github.com/GoogleCloudPlatform/kubernetes/pkg/conversion"
"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
@ -42,6 +43,16 @@ type EtcdHelper struct {
Versioner EtcdVersioner
// prefix for all etcd keys
PathPrefix string
// We cache objects stored in etcd. For keys we use Node.ModifiedIndex which is equivalent
// to resourceVersion.
// This depends on etcd's indexes being globally unique across all objects/types. This will
// have to revisited if we decide to do things like multiple etcd clusters, or etcd will
// support multi-object transaction that will result in many objects with the same index.
// Number of entries stored in the cache is controlled by maxEtcdCacheEntries constant.
// TODO: Measure how much this cache helps after the conversion code is optimized.
cache map[uint64]runtime.Object
mutex *sync.RWMutex
}
// NewEtcdHelper creates a helper that works against objects that use the internal
@ -52,6 +63,8 @@ func NewEtcdHelper(client EtcdGetSet, codec runtime.Codec, prefix string) EtcdHe
Codec: codec,
Versioner: APIObjectVersioner{},
PathPrefix: prefix,
cache: make(map[uint64]runtime.Object),
mutex: new(sync.RWMutex),
}
}
@ -121,19 +134,74 @@ func (h *EtcdHelper) decodeNodeList(nodes []*etcd.Node, slicePtr interface{}) er
}
continue
}
obj := reflect.New(v.Type().Elem())
if err := h.Codec.DecodeInto([]byte(node.Value), obj.Interface().(runtime.Object)); err != nil {
return err
if obj, found := h.getFromCache(node.ModifiedIndex); found {
v.Set(reflect.Append(v, reflect.ValueOf(obj).Elem()))
} else {
obj := reflect.New(v.Type().Elem())
if err := h.Codec.DecodeInto([]byte(node.Value), obj.Interface().(runtime.Object)); err != nil {
return err
}
if h.Versioner != nil {
// being unable to set the version does not prevent the object from being extracted
_ = h.Versioner.UpdateObject(obj.Interface().(runtime.Object), node)
}
v.Set(reflect.Append(v, obj.Elem()))
if node.ModifiedIndex != 0 {
h.addToCache(node.ModifiedIndex, obj.Interface().(runtime.Object))
}
}
if h.Versioner != nil {
// being unable to set the version does not prevent the object from being extracted
_ = h.Versioner.UpdateObject(obj.Interface().(runtime.Object), node)
}
v.Set(reflect.Append(v, obj.Elem()))
}
return nil
}
// etcdCache defines interface used for caching objects stored in etcd. Objects are keyed by
// their Node.ModifiedIndex, which is unique across all types.
// All implementations must be thread-safe.
type etcdCache interface {
getFromCache(index uint64) (runtime.Object, bool)
addToCache(index uint64, obj runtime.Object)
}
const maxEtcdCacheEntries int = 50000
func (h *EtcdHelper) getFromCache(index uint64) (runtime.Object, bool) {
var obj runtime.Object
func() {
h.mutex.RLock()
defer h.mutex.RUnlock()
obj = h.cache[index]
}()
if obj != nil {
// We should not return the object itself to avoid poluting the cache if someone
// modifies returned values.
objCopy, err := conversion.DeepCopy(obj)
if err != nil {
glog.Errorf("Error during DeepCopy of cached object: %q", err)
return nil, false
}
return objCopy.(runtime.Object), true
}
return nil, false
}
func (h *EtcdHelper) addToCache(index uint64, obj runtime.Object) {
objCopy, err := conversion.DeepCopy(obj)
if err != nil {
glog.Errorf("Error during DeepCopy of cached object: %q", err)
return
}
h.mutex.Lock()
defer h.mutex.Unlock()
h.cache[index] = objCopy.(runtime.Object)
if len(h.cache) > maxEtcdCacheEntries {
var randomKey uint64
for randomKey = range h.cache {
break
}
delete(h.cache, randomKey)
}
}
// ExtractToList works on a *List api object (an object that satisfies the runtime.IsList
// definition) and extracts a go object per etcd node into a slice with the resource version.
func (h *EtcdHelper) ExtractToList(key string, listObj runtime.Object) error {

10
pkg/tools/etcd_helper_test.go
View File

@ -174,7 +174,7 @@ func TestExtractToListAcrossDirectories(t *testing.T) {
Key: "/baz",
Value: getEncodedPod("baz"),
Dir: false,
ModifiedIndex: 1,
ModifiedIndex: 3,
},
},
},
@ -199,7 +199,7 @@ func TestExtractToListAcrossDirectories(t *testing.T) {
Items: []api.Pod{
// We expect list to be sorted by directory (e.g. namespace) first, then by name.
{
ObjectMeta: api.ObjectMeta{Name: "baz", ResourceVersion: "1"},
ObjectMeta: api.ObjectMeta{Name: "baz", ResourceVersion: "3"},
Spec: api.PodSpec{
RestartPolicy: api.RestartPolicyAlways,
DNSPolicy: api.DNSClusterFirst,
@ -482,7 +482,8 @@ func TestSetObjWithVersion(t *testing.T) {
func TestSetObjWithoutResourceVersioner(t *testing.T) {
obj := &api.Pod{ObjectMeta: api.ObjectMeta{Name: "foo"}}
fakeClient := NewFakeEtcdClient(t)
helper := EtcdHelper{fakeClient, testapi.Codec(), nil, etcdtest.PathPrefix()}
helper := NewEtcdHelper(fakeClient, testapi.Codec(), etcdtest.PathPrefix())
helper.Versioner = nil
returnedObj := &api.Pod{}
err := helper.SetObj("/some/key", obj, returnedObj, 3)
key := etcdtest.AddPrefix("/some/key")
@ -509,7 +510,8 @@ func TestSetObjWithoutResourceVersioner(t *testing.T) {
func TestSetObjNilOutParam(t *testing.T) {
obj := &api.Pod{ObjectMeta: api.ObjectMeta{Name: "foo"}}
fakeClient := NewFakeEtcdClient(t)
helper := EtcdHelper{fakeClient, testapi.Codec(), nil, etcdtest.PathPrefix()}
helper := NewEtcdHelper(fakeClient, testapi.Codec(), etcdtest.PathPrefix())
helper.Versioner = nil
err := helper.SetObj("/some/key", obj, nil, 3)
if err != nil {
t.Errorf("Unexpected error %#v", err)

18
pkg/tools/etcd_helper_watch.go
View File

@ -72,7 +72,7 @@ func ParseWatchResourceVersion(resourceVersion, kind string) (uint64, error) {
// watching (e.g., for reconnecting without missing any updates).
func (h *EtcdHelper) WatchList(key string, resourceVersion uint64, filter FilterFunc) (watch.Interface, error) {
key = h.PrefixEtcdKey(key)
w := newEtcdWatcher(true, exceptKey(key), filter, h.Codec, h.Versioner, nil)
w := newEtcdWatcher(true, exceptKey(key), filter, h.Codec, h.Versioner, nil, h)
go w.etcdWatch(h.Client, key, resourceVersion)
return w, nil
}
@ -82,7 +82,7 @@ func (h *EtcdHelper) WatchList(key string, resourceVersion uint64, filter Filter
// Errors will be sent down the channel.
func (h *EtcdHelper) Watch(key string, resourceVersion uint64, filter FilterFunc) (watch.Interface, error) {
key = h.PrefixEtcdKey(key)
w := newEtcdWatcher(false, nil, filter, h.Codec, h.Versioner, nil)
w := newEtcdWatcher(false, nil, filter, h.Codec, h.Versioner, nil, h)
go w.etcdWatch(h.Client, key, resourceVersion)
return w, nil
}
@ -105,7 +105,7 @@ func (h *EtcdHelper) Watch(key string, resourceVersion uint64, filter FilterFunc
// Errors will be sent down the channel.
func (h *EtcdHelper) WatchAndTransform(key string, resourceVersion uint64, transform TransformFunc) watch.Interface {
key = h.PrefixEtcdKey(key)
w := newEtcdWatcher(false, nil, Everything, h.Codec, h.Versioner, transform)
w := newEtcdWatcher(false, nil, Everything, h.Codec, h.Versioner, transform, h)
go w.etcdWatch(h.Client, key, resourceVersion)
return w
}
@ -145,6 +145,8 @@ type etcdWatcher struct {
// Injectable for testing. Send the event down the outgoing channel.
emit func(watch.Event)
cache etcdCache
}
// watchWaitDuration is the amount of time to wait for an error from watch.
@ -152,7 +154,7 @@ const watchWaitDuration = 100 * time.Millisecond
// newEtcdWatcher returns a new etcdWatcher; if list is true, watch sub-nodes. If you provide a transform
// and a versioner, the versioner must be able to handle the objects that transform creates.
func newEtcdWatcher(list bool, include includeFunc, filter FilterFunc, encoding runtime.Codec, versioner EtcdVersioner, transform TransformFunc) *etcdWatcher {
func newEtcdWatcher(list bool, include includeFunc, filter FilterFunc, encoding runtime.Codec, versioner EtcdVersioner, transform TransformFunc, cache etcdCache) *etcdWatcher {
w := &etcdWatcher{
encoding: encoding,
versioner: versioner,
@ -165,6 +167,7 @@ func newEtcdWatcher(list bool, include includeFunc, filter FilterFunc, encoding
etcdStop: make(chan bool),
outgoing: make(chan watch.Event),
userStop: make(chan struct{}),
cache: cache,
}
w.emit = func(e watch.Event) { w.outgoing <- e }
go w.translate()
@ -256,6 +259,10 @@ func (w *etcdWatcher) translate() {
}
func (w *etcdWatcher) decodeObject(node *etcd.Node) (runtime.Object, error) {
if obj, found := w.cache.getFromCache(node.ModifiedIndex); found {
return obj, nil
}
obj, err := w.encoding.Decode([]byte(node.Value))
if err != nil {
return nil, err
@ -277,6 +284,9 @@ func (w *etcdWatcher) decodeObject(node *etcd.Node) (runtime.Object, error) {
}
}
if node.ModifiedIndex != 0 {
w.cache.addToCache(node.ModifiedIndex, obj)
}
return obj, nil
}

40
pkg/tools/etcd_helper_watch_test.go
View File

@ -32,6 +32,18 @@ import (
var versioner = APIObjectVersioner{}
// Implements etcdCache interface as empty methods (i.e. does not cache any objects)
type fakeEtcdCache struct{}
func (f *fakeEtcdCache) getFromCache(index uint64) (runtime.Object, bool) {
return nil, false
}
func (f *fakeEtcdCache) addToCache(index uint64, obj runtime.Object) {
}
var _ etcdCache = &fakeEtcdCache{}
func TestWatchInterpretations(t *testing.T) {
codec := latest.Codec
// Declare some pods to make the test cases compact.
@ -115,7 +127,7 @@ func TestWatchInterpretations(t *testing.T) {
for name, item := range table {
for _, action := range item.actions {
w := newEtcdWatcher(true, nil, firstLetterIsB, codec, versioner, nil)
w := newEtcdWatcher(true, nil, firstLetterIsB, codec, versioner, nil, &fakeEtcdCache{})
emitCalled := false
w.emit = func(event watch.Event) {
emitCalled = true
@ -153,7 +165,7 @@ func TestWatchInterpretations(t *testing.T) {
}
func TestWatchInterpretation_ResponseNotSet(t *testing.T) {
w := newEtcdWatcher(false, nil, Everything, codec, versioner, nil)
w := newEtcdWatcher(false, nil, Everything, codec, versioner, nil, &fakeEtcdCache{})
w.emit = func(e watch.Event) {
t.Errorf("Unexpected emit: %v", e)
}
@ -167,7 +179,7 @@ func TestWatchInterpretation_ResponseNotSet(t *testing.T) {
func TestWatchInterpretation_ResponseNoNode(t *testing.T) {
actions := []string{"create", "set", "compareAndSwap", "delete"}
for _, action := range actions {
w := newEtcdWatcher(false, nil, Everything, codec, versioner, nil)
w := newEtcdWatcher(false, nil, Everything, codec, versioner, nil, &fakeEtcdCache{})
w.emit = func(e watch.Event) {
t.Errorf("Unexpected emit: %v", e)
}
@ -181,7 +193,7 @@ func TestWatchInterpretation_ResponseNoNode(t *testing.T) {
func TestWatchInterpretation_ResponseBadData(t *testing.T) {
actions := []string{"create", "set", "compareAndSwap", "delete"}
for _, action := range actions {
w := newEtcdWatcher(false, nil, Everything, codec, versioner, nil)
w := newEtcdWatcher(false, nil, Everything, codec, versioner, nil, &fakeEtcdCache{})
w.emit = func(e watch.Event) {
t.Errorf("Unexpected emit: %v", e)
}
@ -206,7 +218,7 @@ func TestWatchEtcdError(t *testing.T) {
fakeClient := NewFakeEtcdClient(t)
fakeClient.expectNotFoundGetSet["/some/key"] = struct{}{}
fakeClient.WatchImmediateError = fmt.Errorf("immediate error")
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
watching, err := h.Watch("/some/key", 4, Everything)
if err != nil {
@ -236,7 +248,7 @@ func TestWatch(t *testing.T) {
key := "/some/key"
prefixedKey := etcdtest.AddPrefix(key)
fakeClient.expectNotFoundGetSet[prefixedKey] = struct{}{}
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
watching, err := h.Watch(key, 0, Everything)
if err != nil {
@ -412,7 +424,7 @@ func TestWatchEtcdState(t *testing.T) {
fakeClient.Data[key] = value
}
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
watching, err := h.Watch(baseKey, testCase.From, Everything)
if err != nil {
t.Fatalf("Unexpected error: %v", err)
@ -485,7 +497,7 @@ func TestWatchFromZeroIndex(t *testing.T) {
key := "/some/key"
prefixedKey := etcdtest.AddPrefix(key)
fakeClient.Data[prefixedKey] = testCase.Response
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
watching, err := h.Watch(key, 0, Everything)
if err != nil {
@ -546,7 +558,7 @@ func TestWatchListFromZeroIndex(t *testing.T) {
EtcdIndex: 3,
},
}
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
watching, err := h.WatchList(key, 0, Everything)
if err != nil {
@ -586,7 +598,7 @@ func TestWatchListIgnoresRootKey(t *testing.T) {
prefixedKey := etcdtest.AddPrefix(key)
fakeClient := NewFakeEtcdClient(t)
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
watching, err := h.WatchList(key, 1, Everything)
if err != nil {
@ -639,7 +651,7 @@ func TestWatchFromNotFound(t *testing.T) {
ErrorCode: 100,
},
}
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
watching, err := h.Watch(key, 0, Everything)
if err != nil {
@ -666,7 +678,8 @@ func TestWatchFromOtherError(t *testing.T) {
ErrorCode: 101,
},
}
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
watching, err := h.Watch(key, 0, Everything)
if err != nil {
t.Fatalf("Unexpected error: %v", err)
@ -696,7 +709,8 @@ func TestWatchFromOtherError(t *testing.T) {
func TestWatchPurposefulShutdown(t *testing.T) {
fakeClient := NewFakeEtcdClient(t)
h := EtcdHelper{fakeClient, codec, versioner, etcdtest.PathPrefix()}
h := NewEtcdHelper(fakeClient, codec, etcdtest.PathPrefix())
key := "/some/key"
prefixedKey := etcdtest.AddPrefix(key)
fakeClient.expectNotFoundGetSet[prefixedKey] = struct{}{}