+++ /dev/null
-// Copyright (C) The Arvados Authors. All rights reserved.
-//
-// SPDX-License-Identifier: AGPL-3.0
-
-// MultipageLoader retrieves a multi-page result set from the
-// server. The constructor initiates the first page load.
-//
-// config.loadFunc is a function that accepts an array of
-// paging-related filters, and returns a promise for the API
-// response. loadFunc() must retrieve results in "modified_at desc"
-// order.
-//
-// state is:
-// * 'loading' if a network request is in progress;
-// * 'done' if there are no more items to load;
-// * 'ready' otherwise.
-//
-// items is a stream that resolves to an array of all items retrieved so far.
-//
-// loadMore() loads the next page, if any.
-window.MultipageLoader = function(config) {
- var loader = this
- Object.assign(loader, config, {
- state: 'ready',
- DONE: 'done',
- LOADING: 'loading',
- READY: 'ready',
-
- items: m.stream([]),
- thresholdItem: null,
- loadMore: function() {
- if (loader.state == loader.DONE || loader.state == loader.LOADING)
- return
- var filters = loader.thresholdItem ? [
- ["modified_at", "<=", loader.thresholdItem.modified_at],
- ["uuid", "!=", loader.thresholdItem.uuid],
- ] : []
- loader.state = loader.LOADING
- loader.loadFunc(filters).then(function(resp) {
- var items = loader.items()
- Array.prototype.push.apply(items, resp.items)
- if (resp.items.length == 0) {
- loader.state = loader.DONE
- } else {
- loader.thresholdItem = resp.items[resp.items.length-1]
- loader.state = loader.READY
- }
- loader.items(items)
- }).catch(function(err) {
- loader.err = err
- loader.state = loader.READY
- })
- },
- })
- loader.loadMore()
-}
-
-// MergingLoader merges results from multiple loaders (given in the
-// config.children array) into a single result set.
-//
-// new MergingLoader({children: [loader, loader, ...]})
-//
-// The children must retrieve results in "modified_at desc" order.
-window.MergingLoader = function(config) {
- var loader = this
- Object.assign(loader, config, {
- // Sorted items ready to display, merged from all children.
- items: m.stream([]),
- state: 'ready',
- DONE: 'done',
- LOADING: 'loading',
- READY: 'ready',
- loadable: function() {
- // Return an array of children that we could call
- // loadMore() on. Update loader.state.
- loader.state = loader.DONE
- return loader.children.filter(function(child) {
- if (child.state == child.DONE)
- return false
- if (child.state == child.LOADING) {
- loader.state = loader.LOADING
- return false
- }
- if (loader.state == loader.DONE)
- loader.state = loader.READY
- return true
- })
- },
- loadMore: function() {
- // Call loadMore() on children that have reached
- // lowWaterMark.
- loader.loadable().map(function(child) {
- if (child.items().length - child.itemsDisplayed < loader.lowWaterMark) {
- loader.state = loader.LOADING
- child.loadMore()
- }
- })
- },
- mergeItems: function() {
- // We want to avoid moving items around on the screen once
- // they're displayed.
- //
- // To this end, here we find the last safely displayable
- // item ("cutoff") by getting the last item from each
- // unfinished child, and taking the topmost (most recent)
- // one of those.
- //
- // (If we were to display an item below that cutoff, the
- // next page of results from an unfinished child could
- // include items that get inserted above the cutoff,
- // causing the cutoff item to move down.)
- var cutoff
- var cutoffUnknown = false
- loader.children.forEach(function(child) {
- if (child.state == child.DONE)
- return
- var items = child.items()
- if (items.length == 0) {
- // No idea what's coming in the next page.
- cutoffUnknown = true
- return
- }
- var last = items[items.length-1].modified_at
- if (!cutoff || cutoff < last)
- cutoff = last
- })
- if (cutoffUnknown)
- return
- var combined = []
- loader.children.forEach(function(child) {
- child.itemsDisplayed = 0
- child.items().every(function(item) {
- if (cutoff && item.modified_at < cutoff)
- // Don't display this item or anything after
- // it (see "cutoff" comment above).
- return false
- combined.push(item)
- child.itemsDisplayed++
- return true // continue
- })
- })
- loader.items(combined.sort(function(a, b) {
- return a.modified_at < b.modified_at ? 1 : -1
- }))
- },
- // Number of undisplayed items to keep on hand for each result
- // set. When hitting "load more", if a result set already has
- // this many additional results available, we don't bother
- // fetching a new page. This is the _minimum_ number of rows
- // that will be added to loader.items in each "load more"
- // event (except for the case where all items are displayed).
- lowWaterMark: 23,
- })
- var childrenReady = m.stream.merge(loader.children.map(function(child) {
- return child.items
- }))
- childrenReady.map(loader.loadable)
- childrenReady.map(loader.mergeItems)
-}
projects / arvados.git / blobdiff