mirror of
https://github.com/crazy-max/diun.git
synced 2024-12-23 03:48:00 +00:00
332 lines
9.8 KiB
Go
332 lines
9.8 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package meta
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import (
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"errors"
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"fmt"
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"reflect"
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"sync"
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"k8s.io/apimachinery/pkg/conversion"
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"k8s.io/apimachinery/pkg/runtime"
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)
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var (
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// isListCache maintains a cache of types that are checked for lists
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// which is used by IsListType.
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// TODO: remove and replace with an interface check
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isListCache = struct {
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lock sync.RWMutex
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byType map[reflect.Type]bool
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}{
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byType: make(map[reflect.Type]bool, 1024),
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}
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)
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// IsListType returns true if the provided Object has a slice called Items.
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// TODO: Replace the code in this check with an interface comparison by
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// creating and enforcing that lists implement a list accessor.
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func IsListType(obj runtime.Object) bool {
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switch t := obj.(type) {
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case runtime.Unstructured:
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return t.IsList()
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}
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t := reflect.TypeOf(obj)
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isListCache.lock.RLock()
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ok, exists := isListCache.byType[t]
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isListCache.lock.RUnlock()
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if !exists {
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_, err := getItemsPtr(obj)
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ok = err == nil
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// cache only the first 1024 types
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isListCache.lock.Lock()
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if len(isListCache.byType) < 1024 {
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isListCache.byType[t] = ok
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}
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isListCache.lock.Unlock()
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}
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return ok
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}
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var (
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errExpectFieldItems = errors.New("no Items field in this object")
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errExpectSliceItems = errors.New("Items field must be a slice of objects")
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)
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// GetItemsPtr returns a pointer to the list object's Items member.
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// If 'list' doesn't have an Items member, it's not really a list type
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// and an error will be returned.
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// This function will either return a pointer to a slice, or an error, but not both.
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// TODO: this will be replaced with an interface in the future
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func GetItemsPtr(list runtime.Object) (interface{}, error) {
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obj, err := getItemsPtr(list)
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if err != nil {
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return nil, fmt.Errorf("%T is not a list: %v", list, err)
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}
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return obj, nil
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}
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// getItemsPtr returns a pointer to the list object's Items member or an error.
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func getItemsPtr(list runtime.Object) (interface{}, error) {
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v, err := conversion.EnforcePtr(list)
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if err != nil {
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return nil, err
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}
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items := v.FieldByName("Items")
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if !items.IsValid() {
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return nil, errExpectFieldItems
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}
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switch items.Kind() {
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case reflect.Interface, reflect.Pointer:
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target := reflect.TypeOf(items.Interface()).Elem()
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if target.Kind() != reflect.Slice {
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return nil, errExpectSliceItems
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}
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return items.Interface(), nil
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case reflect.Slice:
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return items.Addr().Interface(), nil
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default:
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return nil, errExpectSliceItems
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}
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}
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// EachListItem invokes fn on each runtime.Object in the list. Any error immediately terminates
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// the loop.
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//
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// If items passed to fn are retained for different durations, and you want to avoid
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// retaining all items in obj as long as any item is referenced, use EachListItemWithAlloc instead.
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func EachListItem(obj runtime.Object, fn func(runtime.Object) error) error {
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return eachListItem(obj, fn, false)
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}
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// EachListItemWithAlloc works like EachListItem, but avoids retaining references to the items slice in obj.
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// It does this by making a shallow copy of non-pointer items in obj.
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//
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// If the items passed to fn are not retained, or are retained for the same duration, use EachListItem instead for memory efficiency.
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func EachListItemWithAlloc(obj runtime.Object, fn func(runtime.Object) error) error {
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return eachListItem(obj, fn, true)
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}
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// allocNew: Whether shallow copy is required when the elements in Object.Items are struct
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func eachListItem(obj runtime.Object, fn func(runtime.Object) error, allocNew bool) error {
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if unstructured, ok := obj.(runtime.Unstructured); ok {
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if allocNew {
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return unstructured.EachListItemWithAlloc(fn)
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}
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return unstructured.EachListItem(fn)
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}
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// TODO: Change to an interface call?
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itemsPtr, err := GetItemsPtr(obj)
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if err != nil {
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return err
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}
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items, err := conversion.EnforcePtr(itemsPtr)
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if err != nil {
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return err
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}
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len := items.Len()
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if len == 0 {
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return nil
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}
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takeAddr := false
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if elemType := items.Type().Elem(); elemType.Kind() != reflect.Pointer && elemType.Kind() != reflect.Interface {
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if !items.Index(0).CanAddr() {
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return fmt.Errorf("unable to take address of items in %T for EachListItem", obj)
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}
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takeAddr = true
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}
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for i := 0; i < len; i++ {
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raw := items.Index(i)
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if takeAddr {
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if allocNew {
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// shallow copy to avoid retaining a reference to the original list item
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itemCopy := reflect.New(raw.Type())
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// assign to itemCopy and type-assert
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itemCopy.Elem().Set(raw)
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// reflect.New will guarantee that itemCopy must be a pointer.
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raw = itemCopy
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} else {
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raw = raw.Addr()
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}
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}
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// raw must be a pointer or an interface
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// allocate a pointer is cheap
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switch item := raw.Interface().(type) {
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case *runtime.RawExtension:
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if err := fn(item.Object); err != nil {
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return err
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}
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case runtime.Object:
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if err := fn(item); err != nil {
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return err
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}
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default:
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obj, ok := item.(runtime.Object)
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if !ok {
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return fmt.Errorf("%v: item[%v]: Expected object, got %#v(%s)", obj, i, raw.Interface(), raw.Kind())
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}
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if err := fn(obj); err != nil {
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return err
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}
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}
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}
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return nil
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}
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// ExtractList returns obj's Items element as an array of runtime.Objects.
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// Returns an error if obj is not a List type (does not have an Items member).
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//
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// If items in the returned list are retained for different durations, and you want to avoid
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// retaining all items in obj as long as any item is referenced, use ExtractListWithAlloc instead.
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func ExtractList(obj runtime.Object) ([]runtime.Object, error) {
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return extractList(obj, false)
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}
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// ExtractListWithAlloc works like ExtractList, but avoids retaining references to the items slice in obj.
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// It does this by making a shallow copy of non-pointer items in obj.
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//
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// If the items in the returned list are not retained, or are retained for the same duration, use ExtractList instead for memory efficiency.
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func ExtractListWithAlloc(obj runtime.Object) ([]runtime.Object, error) {
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return extractList(obj, true)
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}
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// allocNew: Whether shallow copy is required when the elements in Object.Items are struct
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func extractList(obj runtime.Object, allocNew bool) ([]runtime.Object, error) {
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itemsPtr, err := GetItemsPtr(obj)
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if err != nil {
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return nil, err
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}
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items, err := conversion.EnforcePtr(itemsPtr)
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if err != nil {
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return nil, err
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}
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list := make([]runtime.Object, items.Len())
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if len(list) == 0 {
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return list, nil
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}
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elemType := items.Type().Elem()
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isRawExtension := elemType == rawExtensionObjectType
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implementsObject := elemType.Implements(objectType)
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for i := range list {
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raw := items.Index(i)
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switch {
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case isRawExtension:
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item := raw.Interface().(runtime.RawExtension)
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switch {
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case item.Object != nil:
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list[i] = item.Object
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case item.Raw != nil:
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// TODO: Set ContentEncoding and ContentType correctly.
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list[i] = &runtime.Unknown{Raw: item.Raw}
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default:
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list[i] = nil
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}
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case implementsObject:
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list[i] = raw.Interface().(runtime.Object)
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case allocNew:
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// shallow copy to avoid retaining a reference to the original list item
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itemCopy := reflect.New(raw.Type())
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// assign to itemCopy and type-assert
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itemCopy.Elem().Set(raw)
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var ok bool
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// reflect.New will guarantee that itemCopy must be a pointer.
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if list[i], ok = itemCopy.Interface().(runtime.Object); !ok {
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return nil, fmt.Errorf("%v: item[%v]: Expected object, got %#v(%s)", obj, i, raw.Interface(), raw.Kind())
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}
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default:
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var found bool
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if list[i], found = raw.Addr().Interface().(runtime.Object); !found {
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return nil, fmt.Errorf("%v: item[%v]: Expected object, got %#v(%s)", obj, i, raw.Interface(), raw.Kind())
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}
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}
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}
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return list, nil
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}
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var (
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// objectSliceType is the type of a slice of Objects
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objectSliceType = reflect.TypeOf([]runtime.Object{})
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objectType = reflect.TypeOf((*runtime.Object)(nil)).Elem()
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rawExtensionObjectType = reflect.TypeOf(runtime.RawExtension{})
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)
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// LenList returns the length of this list or 0 if it is not a list.
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func LenList(list runtime.Object) int {
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itemsPtr, err := GetItemsPtr(list)
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if err != nil {
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return 0
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}
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items, err := conversion.EnforcePtr(itemsPtr)
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if err != nil {
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return 0
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}
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return items.Len()
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}
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// SetList sets the given list object's Items member have the elements given in
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// objects.
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// Returns an error if list is not a List type (does not have an Items member),
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// or if any of the objects are not of the right type.
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func SetList(list runtime.Object, objects []runtime.Object) error {
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itemsPtr, err := GetItemsPtr(list)
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if err != nil {
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return err
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}
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items, err := conversion.EnforcePtr(itemsPtr)
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if err != nil {
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return err
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}
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if items.Type() == objectSliceType {
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items.Set(reflect.ValueOf(objects))
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return nil
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}
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slice := reflect.MakeSlice(items.Type(), len(objects), len(objects))
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for i := range objects {
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dest := slice.Index(i)
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if dest.Type() == rawExtensionObjectType {
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dest = dest.FieldByName("Object")
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}
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// check to see if you're directly assignable
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if reflect.TypeOf(objects[i]).AssignableTo(dest.Type()) {
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dest.Set(reflect.ValueOf(objects[i]))
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continue
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}
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src, err := conversion.EnforcePtr(objects[i])
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if err != nil {
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return err
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}
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if src.Type().AssignableTo(dest.Type()) {
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dest.Set(src)
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} else if src.Type().ConvertibleTo(dest.Type()) {
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dest.Set(src.Convert(dest.Type()))
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} else {
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return fmt.Errorf("item[%d]: can't assign or convert %v into %v", i, src.Type(), dest.Type())
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}
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}
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items.Set(slice)
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return nil
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}
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