Presentation: Add functions that return async iterators for paged responses

common/api/presentation-common.api.md

@@ -1683,6 +1683,8 @@ export class LocalizationHelper {
     // (undocumented)
     getLocalizedLabelDefinitions(labelDefinitions: LabelDefinition[]): LabelDefinition[];
     // (undocumented)
+    getLocalizedNode(node: Node_2): Node_2;
+    // (undocumented)
     getLocalizedNodePathElement(npe: NodePathElement): NodePathElement;
     // (undocumented)
     getLocalizedNodes(nodes: Node_2[]): Node_2[];

common/api/presentation-frontend.api.md

@@ -34,6 +34,7 @@ import { IDisposable } from '@itwin/core-bentley';
 import { IModelConnection } from '@itwin/core-frontend';
 import { InstanceKey } from '@itwin/presentation-common';
 import { InternetConnectivityStatus } from '@itwin/core-common';
+import { Item } from '@itwin/presentation-common';
 import { Key } from '@itwin/presentation-common';
 import { Keys } from '@itwin/presentation-common';
 import { KeySet } from '@itwin/presentation-common';
@@ -44,7 +45,6 @@ import { NodeKey } from '@itwin/presentation-common';
 import { NodePathElement } from '@itwin/presentation-common';
 import { Paged } from '@itwin/presentation-common';
 import { PagedResponse } from '@itwin/presentation-common';
-import { PageOptions } from '@itwin/presentation-common';
 import { RegisteredRuleset } from '@itwin/presentation-common';
 import { RpcRequestsHandler } from '@itwin/presentation-common';
 import { Ruleset } from '@itwin/presentation-common';
@@ -78,9 +78,6 @@ export class BrowserLocalFavoritePropertiesStorage implements IFavoritePropertie
     savePropertiesOrder(orderInfos: FavoritePropertiesOrderInfo[], iTwinId: string | undefined, imodelId: string): Promise<void>;
 }
 
-// @internal (undocumented)
-export const buildPagedArrayResponse: <TItem>(requestedPage: PageOptions | undefined, getter: (page: Required<PageOptions>, requestIndex: number) => Promise<PagedResponse<TItem>>) => Promise<PagedResponse<TItem>>;
-
 // @beta
 export function consoleDiagnosticsHandler(diagnostics: ClientDiagnostics): void;
 
@@ -165,9 +162,18 @@ export enum FavoritePropertiesScope {
     ITwin = 1
 }
 
+// @public
+export type GetContentRequestOptions = ContentRequestOptions<IModelConnection, Descriptor | DescriptorOverrides, KeySet, RulesetVariable> & ClientDiagnosticsAttribute;
+
+// @public
+export type GetDistinctValuesRequestOptions = DistinctValuesRequestOptions<IModelConnection, Descriptor | DescriptorOverrides, KeySet, RulesetVariable> & ClientDiagnosticsAttribute;
+
 // @internal (undocumented)
 export const getFieldInfos: (field: Field) => Set<PropertyFullName>;
 
+// @public
+export type GetNodesRequestOptions = HierarchyRequestOptions<IModelConnection, NodeKey, RulesetVariable> & ClientDiagnosticsAttribute;
+
 // @public @deprecated
 export function getScopeId(scope: SelectionScope | string | undefined): string;
 
@@ -240,6 +246,11 @@ export interface ISelectionProvider {
     selectionChange: SelectionChangeEvent;
 }
 
+// @public
+export type MultipleValuesRequestOptions = Paged<{
+    maxParallelRequests?: number;
+}>;
+
 // @internal (undocumented)
 export class NoopFavoritePropertiesStorage implements IFavoritePropertiesStorage {
     // (undocumented)
@@ -314,32 +325,55 @@ export class PresentationManager implements IDisposable {
     dispose(): void;
     // @internal
     ensureIModelInitialized(_: IModelConnection): Promise<void>;
-    getContent(requestOptions: Paged<ContentRequestOptions<IModelConnection, Descriptor | DescriptorOverrides, KeySet, RulesetVariable>> & ClientDiagnosticsAttribute): Promise<Content | undefined>;
-    getContentAndSize(requestOptions: Paged<ContentRequestOptions<IModelConnection, Descriptor | DescriptorOverrides, KeySet, RulesetVariable>> & ClientDiagnosticsAttribute): Promise<{
+    // @deprecated
+    getContent(requestOptions: GetContentRequestOptions & MultipleValuesRequestOptions): Promise<Content | undefined>;
+    // @deprecated
+    getContentAndSize(requestOptions: GetContentRequestOptions & MultipleValuesRequestOptions): Promise<{
         content: Content;
         size: number;
     } | undefined>;
     getContentDescriptor(requestOptions: ContentDescriptorRequestOptions<IModelConnection, KeySet, RulesetVariable> & ClientDiagnosticsAttribute): Promise<Descriptor | undefined>;
-    getContentInstanceKeys(requestOptions: ContentInstanceKeysRequestOptions<IModelConnection, KeySet, RulesetVariable> & ClientDiagnosticsAttribute): Promise<{
+    getContentInstanceKeys(requestOptions: ContentInstanceKeysRequestOptions<IModelConnection, KeySet, RulesetVariable> & ClientDiagnosticsAttribute & MultipleValuesRequestOptions): Promise<{
         total: number;
         items: () => AsyncGenerator<InstanceKey>;
     }>;
-    getContentSetSize(requestOptions: ContentRequestOptions<IModelConnection, Descriptor | DescriptorOverrides, KeySet, RulesetVariable> & ClientDiagnosticsAttribute): Promise<number>;
+    getContentIterator(requestOptions: GetContentRequestOptions & MultipleValuesRequestOptions): Promise<{
+        descriptor: Descriptor;
+        total: number;
+        items: AsyncIterableIterator<Item>;
+    } | undefined>;
+    getContentSetSize(requestOptions: GetContentRequestOptions): Promise<number>;
     getContentSources(requestOptions: ContentSourcesRequestOptions<IModelConnection> & ClientDiagnosticsAttribute): Promise<SelectClassInfo[]>;
     getDisplayLabelDefinition(requestOptions: DisplayLabelRequestOptions<IModelConnection, InstanceKey> & ClientDiagnosticsAttribute): Promise<LabelDefinition>;
-    getDisplayLabelDefinitions(requestOptions: DisplayLabelsRequestOptions<IModelConnection, InstanceKey> & ClientDiagnosticsAttribute): Promise<LabelDefinition[]>;
+    // @deprecated
+    getDisplayLabelDefinitions(requestOptions: DisplayLabelsRequestOptions<IModelConnection, InstanceKey> & ClientDiagnosticsAttribute & MultipleValuesRequestOptions): Promise<LabelDefinition[]>;
+    getDisplayLabelDefinitionsIterator(requestOptions: DisplayLabelsRequestOptions<IModelConnection, InstanceKey> & ClientDiagnosticsAttribute & MultipleValuesRequestOptions): Promise<{
+        total: number;
+        items: AsyncIterableIterator<LabelDefinition>;
+    }>;
+    getDistinctValuesIterator(requestOptions: GetDistinctValuesRequestOptions & MultipleValuesRequestOptions): Promise<{
+        total: number;
+        items: AsyncIterableIterator<DisplayValueGroup>;
+    }>;
     getElementProperties(requestOptions: SingleElementPropertiesRequestOptions<IModelConnection> & ClientDiagnosticsAttribute): Promise<ElementProperties | undefined>;
     getFilteredNodePaths(requestOptions: FilterByTextHierarchyRequestOptions<IModelConnection, RulesetVariable> & ClientDiagnosticsAttribute): Promise<NodePathElement[]>;
     getNodePaths(requestOptions: FilterByInstancePathsHierarchyRequestOptions<IModelConnection, RulesetVariable> & ClientDiagnosticsAttribute): Promise<NodePathElement[]>;
-    getNodes(requestOptions: Paged<HierarchyRequestOptions<IModelConnection, NodeKey, RulesetVariable>> & ClientDiagnosticsAttribute): Promise<Node_2[]>;
-    getNodesAndCount(requestOptions: Paged<HierarchyRequestOptions<IModelConnection, NodeKey, RulesetVariable>> & ClientDiagnosticsAttribute): Promise<{
+    // @deprecated
+    getNodes(requestOptions: GetNodesRequestOptions & MultipleValuesRequestOptions): Promise<Node_2[]>;
+    // @deprecated
+    getNodesAndCount(requestOptions: GetNodesRequestOptions & MultipleValuesRequestOptions): Promise<{
         count: number;
         nodes: Node_2[];
     }>;
-    getNodesCount(requestOptions: HierarchyRequestOptions<IModelConnection, NodeKey, RulesetVariable> & ClientDiagnosticsAttribute): Promise<number>;
+    getNodesCount(requestOptions: GetNodesRequestOptions): Promise<number>;
     // @beta
     getNodesDescriptor(requestOptions: HierarchyLevelDescriptorRequestOptions<IModelConnection, NodeKey, RulesetVariable> & ClientDiagnosticsAttribute): Promise<Descriptor | undefined>;
-    getPagedDistinctValues(requestOptions: DistinctValuesRequestOptions<IModelConnection, Descriptor | DescriptorOverrides, KeySet, RulesetVariable> & ClientDiagnosticsAttribute): Promise<PagedResponse<DisplayValueGroup>>;
+    getNodesIterator(requestOptions: GetNodesRequestOptions & MultipleValuesRequestOptions): Promise<{
+        total: number;
+        items: AsyncIterableIterator<Node_2>;
+    }>;
+    // @deprecated
+    getPagedDistinctValues(requestOptions: GetDistinctValuesRequestOptions & MultipleValuesRequestOptions): Promise<PagedResponse<DisplayValueGroup>>;
     // @internal (undocumented)
     get ipcRequestsHandler(): IpcRequestsHandler | undefined;
     // @alpha

common/api/summary/presentation-frontend.exports.csv

@@ -1,7 +1,6 @@
 sep=;
 Release Tag;API Item
 internal;BrowserLocalFavoritePropertiesStorage 
-internal;buildPagedArrayResponse: 
 beta;consoleDiagnosticsHandler(diagnostics: ClientDiagnostics): void
 beta;createCombinedDiagnosticsHandler(handlers: ClientDiagnosticsHandler[]): (diagnostics: ClientDiagnostics) => void
 public;createFavoritePropertiesStorage(type: DefaultFavoritePropertiesStorageTypes): IFavoritePropertiesStorage
@@ -15,7 +14,10 @@ public;FavoritePropertiesManager
 public;FavoritePropertiesManagerProps
 public;FavoritePropertiesOrderInfo
 public;FavoritePropertiesScope
+public;GetContentRequestOptions = ContentRequestOptions
+public;GetDistinctValuesRequestOptions = DistinctValuesRequestOptions
 internal;getFieldInfos: (field: Field) => Set
+public;GetNodesRequestOptions = HierarchyRequestOptions
 public;getScopeId(scope: SelectionScope | string | undefined): string
 deprecated;getScopeId(scope: SelectionScope | string | undefined): string
 internal;HILITE_RULESET: Ruleset

common/changes/@itwin/presentation-common/presentation-page-streaming_2024-02-27-14-22.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@itwin/presentation-common",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@itwin/presentation-common"
+}

common/changes/@itwin/presentation-frontend/presentation-page-streaming_2024-02-27-14-22.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@itwin/presentation-frontend",
+      "comment": "Add `getNodesIterator`, `getDistinctValuesIterator`, `getContentIterator` and `getDisplayLabelDefinitionIterator` methods to `PresentationManager` which return async iterators and load data using multiple parallel requests.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@itwin/presentation-frontend"
+}

common/changes/@itwin/presentation-frontend/presentation-page-streaming_2024-02-29-09-30.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@itwin/presentation-frontend",
+      "comment": "Deprecate `getNodes`, `getNodesAndCount`, `getContent`, `getContentAndSize`, `getPagedDistinctValues` and `getDisplayLabelDefinitions` in favor of the alternatives which return iterators.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@itwin/presentation-frontend"
+}

common/changes/@itwin/rpcinterface-full-stack-tests/presentation-page-streaming_2024-03-04-12-33.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@itwin/rpcinterface-full-stack-tests",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@itwin/rpcinterface-full-stack-tests"
+}

docs/changehistory/NextVersion.md

@@ -9,6 +9,8 @@ Table of contents:
   - [Seafloor terrain](#seafloor-terrain)
 - [Electron 29 support](#electron-29-support)
 - [Editor](#editor)
+- [Presentation](#presentation)
+  - [Deprecation of async array results in favor of async iterators](#deprecation-of-async-array-results-in-favor-of-async-iterators)
 
 ## Display
 
@@ -47,3 +49,36 @@ Changes to @beta [CreateElementWithDynamicsTool]($editor-frontend) class:
 
 - [CreateElementWithDynamicsTool.doCreateElement]($editor-frontend) no longer takes an optional [ElementGeometryBuilderParams]($common) as it will be set on the supplied [GeometricElementProps]($common).
 
+## Presentation
+
+### Deprecation of async array results in favor of async iterators
+
+`PresentationManager` contains a number of methods to retrieve sets of results like nodes, content, etc. All of these methods have been deprecated in favor of new ones that return an async iterator instead of an array:
+
+- Use `getContentIterator` instead of `getContent` and `getContentAndSize`.
+- Use `getDisplayLabelDefinitionsIterator` instead of `getDisplayLabelDefinitions`.
+- Use `getDistinctValuesIterator` instead of `getPagedDistinctValues`.
+- Use `getNodesIterator` instead of `getNodes` and `getNodesAndCount`.
+
+All of the above methods, including the deprecated ones, received ability to load large sets of results concurrently. Previously, when requesting a large set (page size > 1000), the result was created by sending a number of requests sequentially by requesting the first page, then the second, and so on, until the whole requested set was retrieved. Now, we send a request for the first page to determine total number of items and backend's page size limit, together with the first page of results, and then other requests are made all at once. At attribute `maxParallelRequests` was added to these methods to control how many parallel requests should be sent at a time.
+
+While performance-wise deprecated methods should be in line with the newly added async iterator ones, the latter have two advantages:
+
+1. Caller can start iterating over results as soon as we receive the first page, instead of having to wait for the whole set.
+2. The iterator version stops sending requests as soon as the caller stops iterating over the async iterator.
+
+> Example: Showing display labels for a large set of elements in a React component.
+>
+> The deprecated approach would be to use `PresentationManager.getDisplayLabelDefinitions` to retrieve labels of all elements. Because the API has to load all the data before returning it to the widget, user has to wait a long time to start seeing the results. Moreover, if he decides to close the widget (the component is unmounted), the `getDisplayLabelDefinitions` keeps building the array by sending requests to the backend - there's no way to cancel that.
+>
+> The new approach is to use `PresentationManager.getDisplayLabelDefinitionsIterator` to get the labels. The labels get streamed to the called as soon as the first results' page is retrieved, so user gets to see initial results quickly, while additional pages keep loading in the background. In addition, if the component is unmounted, iteration can be stopped, thus cancelling all further requests to the backend:
+>
+> ```ts
+> const { items } = await manager.getDisplayLabelDefinitionsIterator(requestProps);
+> for await (const label of items) {
+>  if (isComponentUnmounted) {
+>    break;
+>  }
+>  // update component's model to render the loaded label
+> }
+> ```

full-stack-tests/presentation/src/Utils.ts

@@ -102,3 +102,14 @@ export async function waitFor<T>(check: () => Promise<T> | T, timeout?: number):
   } while (timer.current.milliseconds < timeout);
   throw lastError;
 }
+
+/**
+ * Collects items of an async iterable to an array.
+ */
+export async function collect<T>(iter: AsyncIterable<T>): Promise<T[]> {
+  const result = new Array<T>();
+  for await (const item of iter) {
+    result.push(item);
+  }
+  return result;
+}