mirror of
https://github.com/gravitational/teleport.git
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122 lines
3.7 KiB
Go
122 lines
3.7 KiB
Go
/*
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* Teleport
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* Copyright (C) 2024 Gravitational, Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package utils
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import (
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"context"
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"errors"
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"github.com/gravitational/trace"
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"github.com/gravitational/teleport/lib/utils/pagination"
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)
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// ErrStopIteration is value that signals to stop iteration from the caller injected function.
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var ErrStopIteration = errors.New("stop iteration")
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// ForEachOptions specifies options for ForEachResource.
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type ForEachOptions struct {
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// PageSize is the number of items to fetch per page.
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PageSize int
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}
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// ForEachOptionFunc is a function that sets an option on ForEachOptions.
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type ForEachOptionFunc func(*ForEachOptions)
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// WithPageSize sets the page size option.
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func WithPageSize(pageSize int) ForEachOptionFunc {
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return func(opts *ForEachOptions) {
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opts.PageSize = pageSize
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}
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}
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// TokenLister is a function that lists resources with a page token.
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type TokenLister[T any] func(context.Context, int, string) ([]T, string, error)
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// ForEachResource iterates over resources.
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// Example:
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//
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// count := 0
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// err := ForEachResource(ctx, svc.ListAccessLists, func(acl accesslist.AccessList) error {
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// count++
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// return nil
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// })
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// if err != nil {
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// return trace.Wrap(err)
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// }
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// fmt.Printf("Total access lists: %v", count)
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func ForEachResource[T any](ctx context.Context, listFn TokenLister[T], fn func(T) error, opts ...ForEachOptionFunc) error {
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var options ForEachOptions
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for _, opt := range opts {
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opt(&options)
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}
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pageToken := ""
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for {
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items, nextToken, err := listFn(ctx, options.PageSize, pageToken)
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if err != nil {
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return trace.Wrap(err)
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}
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for _, item := range items {
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if err := fn(item); err != nil {
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if errors.Is(err, ErrStopIteration) {
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return nil
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}
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return trace.Wrap(err)
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}
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}
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if nextToken == "" {
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return nil
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}
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pageToken = nextToken
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}
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}
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// ListerWithPageToken is a function that lists resources with a page token.
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type ListerWithPageToken[T any] func(context.Context, int, *pagination.PageRequestToken) ([]T, pagination.NextPageToken, error)
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// AdaptPageTokenLister adapts a listener with page token to a lister.
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func AdaptPageTokenLister[T any](listFn ListerWithPageToken[T]) TokenLister[T] {
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return func(ctx context.Context, pageSize int, pageToken string) ([]T, string, error) {
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var pageRequestToken pagination.PageRequestToken
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pageRequestToken.Update(pagination.NextPageToken(pageToken))
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resources, nextPageToken, err := listFn(ctx, pageSize, &pageRequestToken)
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if err != nil {
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return nil, "", trace.Wrap(err)
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}
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return resources, string(nextPageToken), nil
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}
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}
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// CollectResources collects resources.
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// Example usage:
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//
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// accessLists err := ForEachResource(ctx, svc.ListAccessLists)
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// fmt.Printf("Total access lists: %v", len(accessLists))
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func CollectResources[T any](ctx context.Context, listFn TokenLister[T], opts ...ForEachOptionFunc) ([]T, error) {
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var results []T
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err := ForEachResource(ctx, listFn, func(item T) error {
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results = append(results, item)
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return nil
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}, opts...)
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if err != nil {
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return nil, trace.Wrap(err)
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}
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return results, nil
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}
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