Golang storage.Filter類代碼示例

// decodeList decodes a list of values into a list of objects, with resource version set to corresponding rev.
// On success, ListPtr would be set to the list of objects.
func decodeList(elems []*elemForDecode, filter storage.Filter, ListPtr interface{}, codec runtime.Codec, versioner storage.Versioner) error {
	v, err := conversion.EnforcePtr(ListPtr)
	if err != nil || v.Kind() != reflect.Slice {
		panic("need ptr to slice")
	}
	for _, elem := range elems {
		obj, _, err := codec.Decode(elem.data, nil, reflect.New(v.Type().Elem()).Interface().(runtime.Object))
		if err != nil {
			return err
		}
		// being unable to set the version does not prevent the object from being extracted
		versioner.UpdateObject(obj, elem.rev)
		if filter.Filter(obj) {
			v.Set(reflect.Append(v, reflect.ValueOf(obj).Elem()))
		}
	}
	return nil
}

// decodeNodeList walks the tree of each node in the list and decodes into the specified object
func (h *etcdHelper) decodeNodeList(nodes []*etcd.Node, filter storage.Filter, slicePtr interface{}) error {
	trace := util.NewTrace("decodeNodeList " + getTypeName(slicePtr))
	defer trace.LogIfLong(400 * time.Millisecond)
	v, err := conversion.EnforcePtr(slicePtr)
	if err != nil || v.Kind() != reflect.Slice {
		// This should not happen at runtime.
		panic("need ptr to slice")
	}
	for _, node := range nodes {
		if node.Dir {
			trace.Step("Decoding dir " + node.Key + " START")
			if err := h.decodeNodeList(node.Nodes, filter, slicePtr); err != nil {
				return err
			}
			trace.Step("Decoding dir " + node.Key + " END")
			continue
		}
		if obj, found := h.getFromCache(node.ModifiedIndex, filter); found {
			// obj != nil iff it matches the filter function.
			if obj != nil {
				v.Set(reflect.Append(v, reflect.ValueOf(obj).Elem()))
			}
		} else {
			obj, _, err := h.codec.Decode([]byte(node.Value), nil, reflect.New(v.Type().Elem()).Interface().(runtime.Object))
			if err != nil {
				return err
			}
			// being unable to set the version does not prevent the object from being extracted
			_ = h.versioner.UpdateObject(obj, node.ModifiedIndex)
			if filter.Filter(obj) {
				v.Set(reflect.Append(v, reflect.ValueOf(obj).Elem()))
			}
			if node.ModifiedIndex != 0 {
				h.addToCache(node.ModifiedIndex, obj)
			}
		}
	}
	trace.Step(fmt.Sprintf("Decoded %v nodes", len(nodes)))
	return nil
}

func (h *etcdHelper) getFromCache(index uint64, filter storage.Filter) (runtime.Object, bool) {
	startTime := time.Now()
	defer func() {
		metrics.ObserveGetCache(startTime)
	}()
	obj, found := h.cache.Get(index)
	if found {
		if !filter.Filter(obj.(runtime.Object)) {
			return nil, true
		}
		// We should not return the object itself to avoid polluting the cache if someone
		// modifies returned values.
		objCopy, err := h.copier.Copy(obj.(runtime.Object))
		if err != nil {
			glog.Errorf("Error during DeepCopy of cached object: %q", err)
			// We can't return a copy, thus we report the object as not found.
			return nil, false
		}
		metrics.ObserveCacheHit()
		return objCopy.(runtime.Object), true
	}
	metrics.ObserveCacheMiss()
	return nil, false
}