mirror of
https://github.com/k3s-io/k3s.git
synced 2024-06-07 19:41:36 +00:00
232 lines
8.0 KiB
Go
232 lines
8.0 KiB
Go
/*
|
|
Copyright 2017 The Kubernetes Authors.
|
|
|
|
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 pager
|
|
|
|
import (
|
|
"context"
|
|
"fmt"
|
|
|
|
"k8s.io/apimachinery/pkg/api/errors"
|
|
"k8s.io/apimachinery/pkg/api/meta"
|
|
metainternalversion "k8s.io/apimachinery/pkg/apis/meta/internalversion"
|
|
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
|
|
"k8s.io/apimachinery/pkg/runtime"
|
|
utilruntime "k8s.io/apimachinery/pkg/util/runtime"
|
|
)
|
|
|
|
const defaultPageSize = 500
|
|
const defaultPageBufferSize = 10
|
|
|
|
// ListPageFunc returns a list object for the given list options.
|
|
type ListPageFunc func(ctx context.Context, opts metav1.ListOptions) (runtime.Object, error)
|
|
|
|
// SimplePageFunc adapts a context-less list function into one that accepts a context.
|
|
func SimplePageFunc(fn func(opts metav1.ListOptions) (runtime.Object, error)) ListPageFunc {
|
|
return func(ctx context.Context, opts metav1.ListOptions) (runtime.Object, error) {
|
|
return fn(opts)
|
|
}
|
|
}
|
|
|
|
// ListPager assists client code in breaking large list queries into multiple
|
|
// smaller chunks of PageSize or smaller. PageFn is expected to accept a
|
|
// metav1.ListOptions that supports paging and return a list. The pager does
|
|
// not alter the field or label selectors on the initial options list.
|
|
type ListPager struct {
|
|
PageSize int64
|
|
PageFn ListPageFunc
|
|
|
|
FullListIfExpired bool
|
|
|
|
// Number of pages to buffer
|
|
PageBufferSize int32
|
|
}
|
|
|
|
// New creates a new pager from the provided pager function using the default
|
|
// options. It will fall back to a full list if an expiration error is encountered
|
|
// as a last resort.
|
|
func New(fn ListPageFunc) *ListPager {
|
|
return &ListPager{
|
|
PageSize: defaultPageSize,
|
|
PageFn: fn,
|
|
FullListIfExpired: true,
|
|
PageBufferSize: defaultPageBufferSize,
|
|
}
|
|
}
|
|
|
|
// TODO: introduce other types of paging functions - such as those that retrieve from a list
|
|
// of namespaces.
|
|
|
|
// List returns a single list object, but attempts to retrieve smaller chunks from the
|
|
// server to reduce the impact on the server. If the chunk attempt fails, it will load
|
|
// the full list instead. The Limit field on options, if unset, will default to the page size.
|
|
func (p *ListPager) List(ctx context.Context, options metav1.ListOptions) (runtime.Object, error) {
|
|
if options.Limit == 0 {
|
|
options.Limit = p.PageSize
|
|
}
|
|
var list *metainternalversion.List
|
|
for {
|
|
select {
|
|
case <-ctx.Done():
|
|
return nil, ctx.Err()
|
|
default:
|
|
}
|
|
|
|
obj, err := p.PageFn(ctx, options)
|
|
if err != nil {
|
|
if !errors.IsResourceExpired(err) || !p.FullListIfExpired {
|
|
return nil, err
|
|
}
|
|
// the list expired while we were processing, fall back to a full list
|
|
options.Limit = 0
|
|
options.Continue = ""
|
|
return p.PageFn(ctx, options)
|
|
}
|
|
m, err := meta.ListAccessor(obj)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("returned object must be a list: %v", err)
|
|
}
|
|
|
|
// exit early and return the object we got if we haven't processed any pages
|
|
if len(m.GetContinue()) == 0 && list == nil {
|
|
return obj, nil
|
|
}
|
|
|
|
// initialize the list and fill its contents
|
|
if list == nil {
|
|
list = &metainternalversion.List{Items: make([]runtime.Object, 0, options.Limit+1)}
|
|
list.ResourceVersion = m.GetResourceVersion()
|
|
list.SelfLink = m.GetSelfLink()
|
|
}
|
|
if err := meta.EachListItem(obj, func(obj runtime.Object) error {
|
|
list.Items = append(list.Items, obj)
|
|
return nil
|
|
}); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// if we have no more items, return the list
|
|
if len(m.GetContinue()) == 0 {
|
|
return list, nil
|
|
}
|
|
|
|
// set the next loop up
|
|
options.Continue = m.GetContinue()
|
|
}
|
|
}
|
|
|
|
// EachListItem fetches runtime.Object items using this ListPager and invokes fn on each item. If
|
|
// fn returns an error, processing stops and that error is returned. If fn does not return an error,
|
|
// any error encountered while retrieving the list from the server is returned. If the context
|
|
// cancels or times out, the context error is returned. Since the list is retrieved in paginated
|
|
// chunks, an "Expired" error (metav1.StatusReasonExpired) may be returned if the pagination list
|
|
// requests exceed the expiration limit of the apiserver being called.
|
|
//
|
|
// Items are retrieved in chunks from the server to reduce the impact on the server with up to
|
|
// ListPager.PageBufferSize chunks buffered concurrently in the background.
|
|
func (p *ListPager) EachListItem(ctx context.Context, options metav1.ListOptions, fn func(obj runtime.Object) error) error {
|
|
return p.eachListChunkBuffered(ctx, options, func(obj runtime.Object) error {
|
|
return meta.EachListItem(obj, fn)
|
|
})
|
|
}
|
|
|
|
// eachListChunkBuffered fetches runtimeObject list chunks using this ListPager and invokes fn on
|
|
// each list chunk. If fn returns an error, processing stops and that error is returned. If fn does
|
|
// not return an error, any error encountered while retrieving the list from the server is
|
|
// returned. If the context cancels or times out, the context error is returned. Since the list is
|
|
// retrieved in paginated chunks, an "Expired" error (metav1.StatusReasonExpired) may be returned if
|
|
// the pagination list requests exceed the expiration limit of the apiserver being called.
|
|
//
|
|
// Up to ListPager.PageBufferSize chunks are buffered concurrently in the background.
|
|
func (p *ListPager) eachListChunkBuffered(ctx context.Context, options metav1.ListOptions, fn func(obj runtime.Object) error) error {
|
|
if p.PageBufferSize < 0 {
|
|
return fmt.Errorf("ListPager.PageBufferSize must be >= 0, got %d", p.PageBufferSize)
|
|
}
|
|
|
|
// Ensure background goroutine is stopped if this call exits before all list items are
|
|
// processed. Cancelation error from this deferred cancel call is never returned to caller;
|
|
// either the list result has already been sent to bgResultC or the fn error is returned and
|
|
// the cancelation error is discarded.
|
|
ctx, cancel := context.WithCancel(ctx)
|
|
defer cancel()
|
|
|
|
chunkC := make(chan runtime.Object, p.PageBufferSize)
|
|
bgResultC := make(chan error, 1)
|
|
go func() {
|
|
defer utilruntime.HandleCrash()
|
|
|
|
var err error
|
|
defer func() {
|
|
close(chunkC)
|
|
bgResultC <- err
|
|
}()
|
|
err = p.eachListChunk(ctx, options, func(chunk runtime.Object) error {
|
|
select {
|
|
case chunkC <- chunk: // buffer the chunk, this can block
|
|
case <-ctx.Done():
|
|
return ctx.Err()
|
|
}
|
|
return nil
|
|
})
|
|
}()
|
|
|
|
for o := range chunkC {
|
|
err := fn(o)
|
|
if err != nil {
|
|
return err // any fn error should be returned immediately
|
|
}
|
|
}
|
|
// promote the results of our background goroutine to the foreground
|
|
return <-bgResultC
|
|
}
|
|
|
|
// eachListChunk fetches runtimeObject list chunks using this ListPager and invokes fn on each list
|
|
// chunk. If fn returns an error, processing stops and that error is returned. If fn does not return
|
|
// an error, any error encountered while retrieving the list from the server is returned. If the
|
|
// context cancels or times out, the context error is returned. Since the list is retrieved in
|
|
// paginated chunks, an "Expired" error (metav1.StatusReasonExpired) may be returned if the
|
|
// pagination list requests exceed the expiration limit of the apiserver being called.
|
|
func (p *ListPager) eachListChunk(ctx context.Context, options metav1.ListOptions, fn func(obj runtime.Object) error) error {
|
|
if options.Limit == 0 {
|
|
options.Limit = p.PageSize
|
|
}
|
|
for {
|
|
select {
|
|
case <-ctx.Done():
|
|
return ctx.Err()
|
|
default:
|
|
}
|
|
|
|
obj, err := p.PageFn(ctx, options)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
m, err := meta.ListAccessor(obj)
|
|
if err != nil {
|
|
return fmt.Errorf("returned object must be a list: %v", err)
|
|
}
|
|
if err := fn(obj); err != nil {
|
|
return err
|
|
}
|
|
// if we have no more items, return.
|
|
if len(m.GetContinue()) == 0 {
|
|
return nil
|
|
}
|
|
// set the next loop up
|
|
options.Continue = m.GetContinue()
|
|
}
|
|
}
|