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boundary/internal/pagination/pagination.go

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15 KiB

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1
package pagination
import (
"context"
"time"
"github.com/hashicorp/boundary/internal/boundary"
"github.com/hashicorp/boundary/internal/errors"
"github.com/hashicorp/boundary/internal/listtoken"
)
// ListResponse represents the response from the paginated list operation.
type ListResponse[T boundary.Resource] struct {
// Items contains the page of items. They have
// been filtered according to the behavior of
// the filter item func, and will always have as
// many items as requested in the page size, unless
// there were not enough elements available, in
// which case it will contain all elements that
// were available.
Items []T
// CompleteListing signifies whether this page contains
// the final item currently available. This indicates
// that it may be appropriate to wait some time before
// requesting additional pages.
CompleteListing bool
// ListToken is the token that the caller can use
// to request a new page of items. The items in the
// new page will have been updated more recently
// than all the items in the previous page. This
// field may be empty if there were no results for a
// List call.
ListToken *listtoken.Token
// DeletedIds contains a list of item IDs that have been
// deleted since the last request for items. This can only happen
// during a refresh pagination.
DeletedIds []string
// EstimatedItemCount is an estimate of exactly how many
// items matching the filter function are available. If
// a List call is complete, this number is equal to
// the number of items returned. Otherwise, the
// estimated count function is consulted for an estimate.
EstimatedItemCount int
}
// ListFilterFunc is a callback used to filter out resources that don't match
// some criteria. The function must return true for items that should be included in the final
// result. Returning an error results in an error being returned from the pagination.
type ListFilterFunc[T boundary.Resource] func(ctx context.Context, item T) (bool, error)
// ListItemsFunc returns a slice of T that are ordered after prevPageLastItem according to
// the implementation of the function. If prevPageLastItem is empty, it should return
// a slice of T from the start, as defined by the function. It also returns the timestamp
// of the DB transaction used to list the items.
type ListItemsFunc[T boundary.Resource] func(ctx context.Context, prevPageLastItem T, limit int) ([]T, time.Time, error)
// EstimatedCountFunc is used to estimate the total number of items
// available for the resource that is being listed.
type EstimatedCountFunc func(ctx context.Context) (int, error)
// ListDeletedIDsFunc is used to list the IDs of the resources deleted since
// the given timestamp. It returns a slice of IDs and the timestamp of the
// DB transaction used to list the IDs.
type ListDeletedIDsFunc func(ctx context.Context, since time.Time) ([]string, time.Time, error)
// List returns a ListResponse. The response will contain at most pageSize
// number of items. Items are fetched using the listItemsFn and checked using
// the filterItemFn to determine if they should be included in the response.
// The response includes a new list token used to continue pagination or refresh.
// The estimatedCountFn is used to provide an estimated total number of
// items that can be returned by making additional requests using the returned
// list token.
func List[T boundary.Resource](
ctx context.Context,
grantsHash []byte,
pageSize int,
filterItemFn ListFilterFunc[T],
listItemsFn ListItemsFunc[T],
estimatedCountFn EstimatedCountFunc,
) (*ListResponse[T], error) {
const op = "pagination.List"
switch {
case len(grantsHash) == 0:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing grants hash")
case pageSize < 1:
return nil, errors.New(ctx, errors.InvalidParameter, op, "page size must be at least 1")
case filterItemFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing filter item callback")
case listItemsFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list items callback")
case estimatedCountFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing estimated count callback")
}
items, completeListing, listTime, err := list(ctx, pageSize, filterItemFn, listItemsFn)
if err != nil {
return nil, errors.Wrap(ctx, err, op)
}
return buildListResp(ctx, grantsHash, items, completeListing, listTime, estimatedCountFn)
}
// ListPage returns a ListResponse. The response will contain at most pageSize
// number of items. Items are fetched using the listItemsFn and checked using
// the filterItemFn to determine if they should be included in the response.
// Items will be fetched based on the contents of the list token. The list
// token must contain a PaginationToken component.
// The response includes a new list token used to continue pagination or refresh.
// The estimatedCountFn is used to provide an estimated total number of
// items that can be returned by making additional requests using the returned
// list token.
func ListPage[T boundary.Resource](
ctx context.Context,
grantsHash []byte,
pageSize int,
filterItemFn ListFilterFunc[T],
listItemsFn ListItemsFunc[T],
estimatedCountFn EstimatedCountFunc,
tok *listtoken.Token,
) (*ListResponse[T], error) {
const op = "pagination.ListPage"
switch {
case len(grantsHash) == 0:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing grants hash")
case pageSize < 1:
return nil, errors.New(ctx, errors.InvalidParameter, op, "page size must be at least 1")
case filterItemFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing filter item callback")
case listItemsFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list items callback")
case estimatedCountFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing estimated count callback")
case tok == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list token")
}
if _, ok := tok.Subtype.(*listtoken.PaginationToken); !ok {
return nil, errors.New(ctx, errors.InvalidParameter, op, "token did not have a pagination token component")
}
items, completeListing, listTime, err := list(ctx, pageSize, filterItemFn, listItemsFn)
if err != nil {
return nil, errors.Wrap(ctx, err, op)
}
return buildListPageResp(ctx, completeListing, nil, time.Time{} /* no deleted ids time */, items, listTime, tok, estimatedCountFn)
}
// ListRefresh returns a ListResponse. The response will contain at most pageSize
// number of items. Items are fetched using the listItemsFn and checked using
// the filterItemFn to determine if they should be included in the response.
// Items will be fetched based on the contents of the list token. The list
// token must contain a StartRefreshToken component.
// The response includes a new list token used to continue pagination or refresh.
// The estimatedCountFn is used to provide an estimated total number of
// items that can be returned by making additional requests using the returned
// list token. The listDeletedIDsFn is used to list the IDs of any
// resources that have been deleted since the list token was last used.
func ListRefresh[T boundary.Resource](
ctx context.Context,
grantsHash []byte,
pageSize int,
filterItemFn ListFilterFunc[T],
listItemsFn ListItemsFunc[T],
estimatedCountFn EstimatedCountFunc,
listDeletedIDsFn ListDeletedIDsFunc,
tok *listtoken.Token,
) (*ListResponse[T], error) {
const op = "pagination.ListRefresh"
switch {
case len(grantsHash) == 0:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing grants hash")
case pageSize < 1:
return nil, errors.New(ctx, errors.InvalidParameter, op, "page size must be at least 1")
case filterItemFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing filter item callback")
case listItemsFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list items callback")
case estimatedCountFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing estimated count callback")
case listDeletedIDsFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list deleted IDs callback")
case tok == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list token")
}
srt, ok := tok.Subtype.(*listtoken.StartRefreshToken)
if !ok {
return nil, errors.New(ctx, errors.InvalidParameter, op, "token did not have a start-refresh token component")
}
deletedIds, deletedIdsTime, err := listDeletedIDsFn(ctx, srt.PreviousDeletedIdsTime)
if err != nil {
return nil, errors.Wrap(ctx, err, op)
}
items, completeListing, listTime, err := list(ctx, pageSize, filterItemFn, listItemsFn)
if err != nil {
return nil, errors.Wrap(ctx, err, op)
}
return buildListPageResp(ctx, completeListing, deletedIds, deletedIdsTime, items, listTime, tok, estimatedCountFn)
}
// ListRefreshPage returns a ListResponse. The response will contain at most pageSize
// number of items. Items are fetched using the listItemsFn and checked using
// the filterItemFn to determine if they should be included in the response.
// Items will be fetched based on the contents of the list token. The list
// token must contain a RefreshToken component.
// The response includes a new list token used to continue pagination or refresh.
// The estimatedCountFn is used to provide an estimated total number of
// items that can be returned by making additional requests using the returned
// list token. The listDeletedIDsFn is used to list the IDs of any
// resources that have been deleted since the list token was last used.
func ListRefreshPage[T boundary.Resource](
ctx context.Context,
grantsHash []byte,
pageSize int,
filterItemFn ListFilterFunc[T],
listItemsFn ListItemsFunc[T],
estimatedCountFn EstimatedCountFunc,
listDeletedIDsFn ListDeletedIDsFunc,
tok *listtoken.Token,
) (*ListResponse[T], error) {
const op = "pagination.ListRefreshPage"
switch {
case len(grantsHash) == 0:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing grants hash")
case pageSize < 1:
return nil, errors.New(ctx, errors.InvalidParameter, op, "page size must be at least 1")
case filterItemFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing filter item callback")
case listItemsFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list items callback")
case estimatedCountFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing estimated count callback")
case listDeletedIDsFn == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list deleted IDs callback")
case tok == nil:
return nil, errors.New(ctx, errors.InvalidParameter, op, "missing list token")
}
rt, ok := tok.Subtype.(*listtoken.RefreshToken)
if !ok {
return nil, errors.New(ctx, errors.InvalidParameter, op, "token did not have a refresh token component")
}
deletedIds, deletedIdsTime, err := listDeletedIDsFn(ctx, rt.PreviousDeletedIdsTime)
if err != nil {
return nil, errors.Wrap(ctx, err, op)
}
items, completeListing, listTime, err := list(ctx, pageSize, filterItemFn, listItemsFn)
if err != nil {
return nil, errors.Wrap(ctx, err, op)
}
return buildListPageResp(ctx, completeListing, deletedIds, deletedIdsTime, items, listTime, tok, estimatedCountFn)
}
func list[T boundary.Resource](
ctx context.Context,
pageSize int,
filterItemFn ListFilterFunc[T],
listItemsFn ListItemsFunc[T],
) ([]T, bool, time.Time, error) {
const op = "pagination.list"
var lastItem T
var firstListTime time.Time
limit := pageSize + 1
items := make([]T, 0, limit)
dbLoop:
for {
// Request another page from the DB until we fill the final items
page, listTime, err := listItemsFn(ctx, lastItem, limit)
if err != nil {
return nil, false, time.Time{}, errors.Wrap(ctx, err, op)
}
// Assign the firstListTime once, to ensure we always store the start of listing,
// rather the timestamp of the last listing.
if firstListTime.IsZero() {
firstListTime = listTime
}
for _, item := range page {
ok, err := filterItemFn(ctx, item)
if err != nil {
return nil, false, time.Time{}, errors.Wrap(ctx, err, op)
}
if ok {
items = append(items, item)
// If we filled the items after filtering,
// we're done.
if len(items) == cap(items) {
break dbLoop
}
}
}
// If the current page was shorter than the limit, stop iterating
if len(page) < limit {
break dbLoop
}
lastItem = page[len(page)-1]
}
// If we couldn't fill the items, it was a complete listing.
completeListing := len(items) < cap(items)
if !completeListing {
// Items is of size pageSize+1, so
// truncate if it was filled.
items = items[:pageSize]
}
return items, completeListing, firstListTime, nil
}
func buildListResp[T boundary.Resource](
ctx context.Context,
grantsHash []byte,
items []T,
completeListing bool,
listTime time.Time,
estimatedCountFn EstimatedCountFunc,
) (*ListResponse[T], error) {
resp := &ListResponse[T]{
Items: items,
CompleteListing: completeListing,
EstimatedItemCount: len(items),
}
var err error
if len(items) > 0 {
lastItem := items[len(items)-1]
if completeListing {
// If this is the only page in the pagination, create a
// start refresh token so subsequent requests are informed
// that they need to start a new refresh phase.
resp.ListToken, err = listtoken.NewStartRefresh(
ctx,
listTime, // Use list time as the create time of the token
lastItem.GetResourceType(),
grantsHash,
listTime, // Use list time as the starting point for listing deleted ids
listTime, // Use list time as the lower bound for subsequent refresh
)
if err != nil {
return nil, err
}
} else {
resp.ListToken, err = listtoken.NewPagination(
ctx,
listTime, // Use list time as the create time of the token
lastItem.GetResourceType(),
grantsHash,
lastItem.GetPublicId(),
lastItem.GetCreateTime().AsTime(),
)
if err != nil {
return nil, err
}
}
}
if !completeListing {
// If this was not a complete listing, get an estimate
// of the total items from the DB.
var err error
resp.EstimatedItemCount, err = estimatedCountFn(ctx)
if err != nil {
return nil, err
}
}
return resp, err
}
func buildListPageResp[T boundary.Resource](
ctx context.Context,
completeListing bool,
deletedIds []string,
deletedIdsTime time.Time,
items []T,
listTime time.Time,
tok *listtoken.Token,
estimatedCountFn EstimatedCountFunc,
) (*ListResponse[T], error) {
resp := &ListResponse[T]{
Items: items,
CompleteListing: completeListing,
ListToken: tok,
DeletedIds: deletedIds,
}
var err error
resp.EstimatedItemCount, err = estimatedCountFn(ctx)
if err != nil {
return nil, err
}
var lastItem boundary.Resource
if len(items) > 0 {
lastItem = items[len(items)-1]
}
if err := resp.ListToken.Transition(
ctx,
completeListing,
lastItem,
deletedIdsTime,
listTime,
); err != nil {
return nil, err
}
return resp, err
}