ui/src/core/trace_impl.ts - third_party/perfetto - Git at Google

 // Copyright (C) 2024 The Android Open Source Project
 //
 // 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.

 import {DisposableStack} from '../base/disposable_stack';
 import {createStore, Migrate, Store} from '../base/store';
 import {TimelineImpl} from './timeline';
 import {Command} from '../public/command';
 import {EventListeners, Trace} from '../public/trace';
 import {ScrollToArgs, setScrollToFunction} from '../public/scroll_helper';
 import {TrackDescriptor} from '../public/track';
 import {EngineBase, EngineProxy} from '../trace_processor/engine';
 import {CommandManagerImpl} from './command_manager';
 import {NoteManagerImpl} from './note_manager';
 import {OmniboxManagerImpl} from './omnibox_manager';
 import {SearchManagerImpl} from './search_manager';
 import {SelectionManagerImpl} from './selection_manager';
 import {SidebarManagerImpl} from './sidebar_manager';
 import {TabManagerImpl} from './tab_manager';
 import {TrackManagerImpl} from './track_manager';
 import {WorkspaceManagerImpl} from './workspace_manager';
 import {SidebarMenuItem} from '../public/sidebar';
 import {ScrollHelper} from './scroll_helper';
 import {Selection, SelectionOpts} from '../public/selection';
 import {SearchResult} from '../public/search';
 import {PivotTableManager} from './pivot_table_manager';
 import {FlowManager} from './flow_manager';
 import {AppContext, AppImpl} from './app_impl';
 import {PluginManagerImpl} from './plugin_manager';
 import {RouteArgs} from '../public/route_schema';
 import {CORE_PLUGIN_ID} from './plugin_manager';
 import {Analytics} from '../public/analytics';
 import {getOrCreate} from '../base/utils';
 import {fetchWithProgress} from '../base/http_utils';
 import {TraceInfoImpl} from './trace_info_impl';
 import {PageHandler, PageManager} from '../public/page';
 import {createProxy} from '../base/utils';
 import {PageManagerImpl} from './page_manager';
 import {FeatureFlagManager, FlagSettings} from '../public/feature_flag';
 import {featureFlags} from './feature_flags';
 import {SerializedAppState} from './state_serialization_schema';
 import {PostedTrace} from './trace_source';
 import {PerfManager} from './perf_manager';

 /**
  * Handles the per-trace state of the UI
  * There is an instance of this class per each trace loaded, and typically
  * between 0 and 1 instances in total (% brief moments while we swap traces).
  * 90% of the app state live here, including the Engine.
  * This is the underlying storage for AppImpl, which instead has one instance
  * per trace per plugin.
  */
 export class TraceContext implements Disposable {
   private readonly pluginInstances = new Map<string, TraceImpl>();
   readonly appCtx: AppContext;
   readonly engine: EngineBase;
   readonly omniboxMgr = new OmniboxManagerImpl();
   readonly searchMgr: SearchManagerImpl;
   readonly selectionMgr: SelectionManagerImpl;
   readonly tabMgr = new TabManagerImpl();
   readonly timeline: TimelineImpl;
   readonly traceInfo: TraceInfoImpl;
   readonly trackMgr = new TrackManagerImpl();
   readonly workspaceMgr = new WorkspaceManagerImpl();
   readonly noteMgr = new NoteManagerImpl();
   readonly flowMgr: FlowManager;
   readonly pluginSerializableState = createStore<{[key: string]: {}}>({});
   readonly scrollHelper: ScrollHelper;
   readonly pivotTableMgr;
   readonly trash = new DisposableStack();
   readonly eventListeners = new Map<keyof EventListeners, Array<unknown>>();

   // List of errors that were encountered while loading the trace by the TS
   // code. These are on top of traceInfo.importErrors, which is a summary of
   // what TraceProcessor reports on the stats table at import time.
   readonly loadingErrors: string[] = [];

   constructor(gctx: AppContext, engine: EngineBase, traceInfo: TraceInfoImpl) {
     this.appCtx = gctx;
     this.engine = engine;
     this.trash.use(engine);
     this.traceInfo = traceInfo;
     this.timeline = new TimelineImpl(traceInfo);

     this.scrollHelper = new ScrollHelper(
       this.traceInfo,
       this.timeline,
       this.workspaceMgr.currentWorkspace,
       this.trackMgr,
     );

     this.selectionMgr = new SelectionManagerImpl(
       this.engine,
       this.trackMgr,
       this.noteMgr,
       this.scrollHelper,
       this.onSelectionChange.bind(this),
     );

     this.noteMgr.onNoteDeleted = (noteId) => {
       if (
         this.selectionMgr.selection.kind === 'note' &&
         this.selectionMgr.selection.id === noteId
       ) {
         this.selectionMgr.clear();
       }
     };

     this.pivotTableMgr = new PivotTableManager(
       engine.getProxy('PivotTableManager'),
     );

     this.flowMgr = new FlowManager(
       engine.getProxy('FlowManager'),
       this.trackMgr,
       this.selectionMgr,
     );

     this.searchMgr = new SearchManagerImpl({
       timeline: this.timeline,
       trackManager: this.trackMgr,
       engine: this.engine,
       workspace: this.workspaceMgr.currentWorkspace,
       onResultStep: this.onResultStep.bind(this),
     });
   }

   // This method wires up changes to selection to side effects on search and
   // tabs. This is to avoid entangling too many dependencies between managers.
   private onSelectionChange(selection: Selection, opts: SelectionOpts) {
     const {clearSearch = true, switchToCurrentSelectionTab = true} = opts;
     if (clearSearch) {
       this.searchMgr.reset();
     }
     if (switchToCurrentSelectionTab && selection.kind !== 'empty') {
       this.tabMgr.showCurrentSelectionTab();
     }

     if (selection.kind === 'area') {
       this.pivotTableMgr.setSelectionArea(selection);
     }

     this.flowMgr.updateFlows(selection);
   }

   private onResultStep(searchResult: SearchResult) {
     this.selectionMgr.selectSearchResult(searchResult);
   }

   // Gets or creates an instance of TraceImpl backed by the current TraceContext
   // for the given plugin.
   forPlugin(pluginId: string) {
     return getOrCreate(this.pluginInstances, pluginId, () => {
       const appForPlugin = this.appCtx.forPlugin(pluginId);
       return new TraceImpl(appForPlugin, this);
     });
   }

   // Called by AppContext.closeCurrentTrace().
   [Symbol.dispose]() {
     this.trash.dispose();
   }
 }

 /**
  * This implementation provides the plugin access to trace related resources,
  * such as the engine and the store. This exists for the whole duration a plugin
  * is active AND a trace is loaded.
  * There are N+1 instances of this for each trace, one for each plugin plus one
  * for the core.
  */
 export class TraceImpl implements Trace {
   private readonly appImpl: AppImpl;
   private readonly traceCtx: TraceContext;

   // This is not the original Engine base, rather an EngineProxy based on the
   // same engineBase.
   private readonly engineProxy: EngineProxy;
   private readonly trackMgrProxy: TrackManagerImpl;
   private readonly commandMgrProxy: CommandManagerImpl;
   private readonly sidebarProxy: SidebarManagerImpl;
   private readonly pageMgrProxy: PageManagerImpl;

   // This is called by TraceController when loading a new trace, soon after the
   // engine has been set up. It obtains a new TraceImpl for the core. From that
   // we can fork sibling instances (i.e. bound to the same TraceContext) for
   // the various plugins.
   static createInstanceForCore(
     appImpl: AppImpl,
     engine: EngineBase,
     traceInfo: TraceInfoImpl,
   ): TraceImpl {
     const traceCtx = new TraceContext(
       appImpl.__appCtxForTrace,
       engine,
       traceInfo,
     );
     return traceCtx.forPlugin(CORE_PLUGIN_ID);
   }

   // Only called by TraceContext.forPlugin().
   constructor(appImpl: AppImpl, ctx: TraceContext) {
     const pluginId = appImpl.pluginId;
     this.appImpl = appImpl;
     this.traceCtx = ctx;
     const traceUnloadTrash = ctx.trash;

     // Invalidate all the engine proxies when the TraceContext is destroyed.
     this.engineProxy = ctx.engine.getProxy(pluginId);
     traceUnloadTrash.use(this.engineProxy);

     // Intercept the registerTrack() method to inject the pluginId into tracks.
     this.trackMgrProxy = createProxy(ctx.trackMgr, {
       registerTrack(trackDesc: TrackDescriptor): Disposable {
         return ctx.trackMgr.registerTrack({...trackDesc, pluginId});
       },
     });

     // CommandManager is global. Here we intercept the registerCommand() because
     // we want any commands registered via the Trace interface to be
     // unregistered when the trace unloads (before a new trace is loaded) to
     // avoid ending up with duplicate commands.
     this.commandMgrProxy = createProxy(ctx.appCtx.commandMgr, {
       registerCommand(cmd: Command): Disposable {
         const disposable = appImpl.commands.registerCommand(cmd);
         traceUnloadTrash.use(disposable);
         return disposable;
       },
     });

     // Likewise, remove all trace-scoped sidebar entries when the trace unloads.
     this.sidebarProxy = createProxy(ctx.appCtx.sidebarMgr, {
       addMenuItem(menuItem: SidebarMenuItem): Disposable {
         const disposable = appImpl.sidebar.addMenuItem(menuItem);
         traceUnloadTrash.use(disposable);
         return disposable;
       },
     });

     this.pageMgrProxy = createProxy(ctx.appCtx.pageMgr, {
       registerPage(pageHandler: PageHandler): Disposable {
         const disposable = appImpl.pages.registerPage({
           ...pageHandler,
           pluginId: appImpl.pluginId,
         });
         traceUnloadTrash.use(disposable);
         return disposable;
       },
     });

     // TODO(primiano): remove this injection once we plumb Trace everywhere.
     setScrollToFunction((x: ScrollToArgs) => ctx.scrollHelper.scrollTo(x));
   }

   scrollTo(where: ScrollToArgs): void {
     this.traceCtx.scrollHelper.scrollTo(where);
   }

   // Creates an instance of TraceImpl backed by the same TraceContext for
   // another plugin. This is effectively a way to "fork" the core instance and
   // create the N instances for plugins.
   forkForPlugin(pluginId: string) {
     return this.traceCtx.forPlugin(pluginId);
   }

   mountStore<T>(migrate: Migrate<T>): Store<T> {
     return this.traceCtx.pluginSerializableState.createSubStore(
       [this.pluginId],
       migrate,
     );
   }

   getPluginStoreForSerialization() {
     return this.traceCtx.pluginSerializableState;
   }

   async getTraceFile(): Promise<Blob> {
     const src = this.traceInfo.source;
     if (this.traceInfo.downloadable) {
       if (src.type === 'ARRAY_BUFFER') {
         return new Blob([src.buffer]);
       } else if (src.type === 'FILE') {
         return src.file;
       } else if (src.type === 'URL') {
         return await fetchWithProgress(src.url, (progressPercent: number) =>
           this.omnibox.showStatusMessage(
             `Downloading trace ${progressPercent}%`,
           ),
         );
       }
     }
     // Not available in HTTP+RPC mode. Rather than propagating an undefined,
     // show a graceful error (the ERR:trace_src will be intercepted by
     // error_dialog.ts). We expect all users of this feature to not be able to
     // do anything useful if we returned undefined (other than showing the same
     // dialog).
     // The caller was supposed to check that traceInfo.downloadable === true
     // before calling this. Throwing while downloadable is true is a bug.
     throw new Error(`Cannot getTraceFile(${src.type})`);
   }

   get openerPluginArgs(): {[key: string]: unknown} | undefined {
     const traceSource = this.traceCtx.traceInfo.source;
     if (traceSource.type !== 'ARRAY_BUFFER') {
       return undefined;
     }
     const pluginArgs = traceSource.pluginArgs;
     return (pluginArgs ?? {})[this.pluginId];
   }

   get trace() {
     return this;
   }

   get engine() {
     return this.engineProxy;
   }

   get timeline() {
     return this.traceCtx.timeline;
   }

   get tracks() {
     return this.trackMgrProxy;
   }

   get tabs() {
     return this.traceCtx.tabMgr;
   }

   get workspace() {
     return this.traceCtx.workspaceMgr.currentWorkspace;
   }

   get workspaces() {
     return this.traceCtx.workspaceMgr;
   }

   get search() {
     return this.traceCtx.searchMgr;
   }

   get selection() {
     return this.traceCtx.selectionMgr;
   }

   get traceInfo(): TraceInfoImpl {
     return this.traceCtx.traceInfo;
   }

   get notes() {
     return this.traceCtx.noteMgr;
   }

   get pivotTable() {
     return this.traceCtx.pivotTableMgr;
   }

   get flows() {
     return this.traceCtx.flowMgr;
   }

   get loadingErrors(): ReadonlyArray<string> {
     return this.traceCtx.loadingErrors;
   }

   addLoadingError(err: string) {
     this.traceCtx.loadingErrors.push(err);
   }

   // App interface implementation.

   get pluginId(): string {
     return this.appImpl.pluginId;
   }

   get commands(): CommandManagerImpl {
     return this.commandMgrProxy;
   }

   get sidebar(): SidebarManagerImpl {
     return this.sidebarProxy;
   }

   get pages(): PageManager {
     return this.pageMgrProxy;
   }

   get omnibox(): OmniboxManagerImpl {
     return this.appImpl.omnibox;
   }

   get plugins(): PluginManagerImpl {
     return this.appImpl.plugins;
   }

   get analytics(): Analytics {
     return this.appImpl.analytics;
   }

   get initialRouteArgs(): RouteArgs {
     return this.appImpl.initialRouteArgs;
   }

   get featureFlags(): FeatureFlagManager {
     return {
       register: (settings: FlagSettings) => featureFlags.register(settings),
     };
   }

   scheduleFullRedraw(): void {
     this.appImpl.scheduleFullRedraw();
   }

   navigate(newHash: string): void {
     this.appImpl.navigate(newHash);
   }

   openTraceFromFile(file: File): void {
     this.appImpl.openTraceFromFile(file);
   }

   openTraceFromUrl(url: string, serializedAppState?: SerializedAppState) {
     this.appImpl.openTraceFromUrl(url, serializedAppState);
   }

   openTraceFromBuffer(args: PostedTrace): void {
     this.appImpl.openTraceFromBuffer(args);
   }

   addEventListener<T extends keyof EventListeners>(
     event: T,
     callback: EventListeners[T],
   ): void {
     const listeners = getOrCreate(
       this.traceCtx.eventListeners,
       event,
       () => [],
     );
     listeners.push(callback);
   }

   getEventListeners<T extends keyof EventListeners>(
     event: T,
   ): ReadonlyArray<EventListeners[T]> {
     const listeners = this.traceCtx.eventListeners.get(event);
     if (listeners) {
       return listeners as ReadonlyArray<EventListeners[T]>;
     } else {
       return [];
     }
   }

   get perfDebugging(): PerfManager {
     return this.appImpl.perfDebugging;
   }

   get trash(): DisposableStack {
     return this.traceCtx.trash;
   }

   // Nothing other than AppImpl should ever refer to this, hence the __ name.
   get __traceCtxForApp() {
     return this.traceCtx;
   }
 }

 // A convenience interface to inject the App in Mithril components.
 export interface TraceImplAttrs {
   trace: TraceImpl;
 }

 export interface OptionalTraceImplAttrs {
   trace?: TraceImpl;
 }
	// Copyright (C) 2024 The Android Open Source Project
	//
	// 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.

	import {DisposableStack} from '../base/disposable_stack';
	import {createStore, Migrate, Store} from '../base/store';
	import {TimelineImpl} from './timeline';
	import {Command} from '../public/command';
	import {EventListeners, Trace} from '../public/trace';
	import {ScrollToArgs, setScrollToFunction} from '../public/scroll_helper';
	import {TrackDescriptor} from '../public/track';
	import {EngineBase, EngineProxy} from '../trace_processor/engine';
	import {CommandManagerImpl} from './command_manager';
	import {NoteManagerImpl} from './note_manager';
	import {OmniboxManagerImpl} from './omnibox_manager';
	import {SearchManagerImpl} from './search_manager';
	import {SelectionManagerImpl} from './selection_manager';
	import {SidebarManagerImpl} from './sidebar_manager';
	import {TabManagerImpl} from './tab_manager';
	import {TrackManagerImpl} from './track_manager';
	import {WorkspaceManagerImpl} from './workspace_manager';
	import {SidebarMenuItem} from '../public/sidebar';
	import {ScrollHelper} from './scroll_helper';
	import {Selection, SelectionOpts} from '../public/selection';
	import {SearchResult} from '../public/search';
	import {PivotTableManager} from './pivot_table_manager';
	import {FlowManager} from './flow_manager';
	import {AppContext, AppImpl} from './app_impl';
	import {PluginManagerImpl} from './plugin_manager';
	import {RouteArgs} from '../public/route_schema';
	import {CORE_PLUGIN_ID} from './plugin_manager';
	import {Analytics} from '../public/analytics';
	import {getOrCreate} from '../base/utils';
	import {fetchWithProgress} from '../base/http_utils';
	import {TraceInfoImpl} from './trace_info_impl';
	import {PageHandler, PageManager} from '../public/page';
	import {createProxy} from '../base/utils';
	import {PageManagerImpl} from './page_manager';
	import {FeatureFlagManager, FlagSettings} from '../public/feature_flag';
	import {featureFlags} from './feature_flags';
	import {SerializedAppState} from './state_serialization_schema';
	import {PostedTrace} from './trace_source';
	import {PerfManager} from './perf_manager';

	/**
	* Handles the per-trace state of the UI
	* There is an instance of this class per each trace loaded, and typically
	* between 0 and 1 instances in total (% brief moments while we swap traces).
	* 90% of the app state live here, including the Engine.
	* This is the underlying storage for AppImpl, which instead has one instance
	* per trace per plugin.
	*/
	export class TraceContext implements Disposable {
	private readonly pluginInstances = new Map<string, TraceImpl>();
	readonly appCtx: AppContext;
	readonly engine: EngineBase;
	readonly omniboxMgr = new OmniboxManagerImpl();
	readonly searchMgr: SearchManagerImpl;
	readonly selectionMgr: SelectionManagerImpl;
	readonly tabMgr = new TabManagerImpl();
	readonly timeline: TimelineImpl;
	readonly traceInfo: TraceInfoImpl;
	readonly trackMgr = new TrackManagerImpl();
	readonly workspaceMgr = new WorkspaceManagerImpl();
	readonly noteMgr = new NoteManagerImpl();
	readonly flowMgr: FlowManager;
	readonly pluginSerializableState = createStore<{[key: string]: {}}>({});
	readonly scrollHelper: ScrollHelper;
	readonly pivotTableMgr;
	readonly trash = new DisposableStack();
	readonly eventListeners = new Map<keyof EventListeners, Array<unknown>>();

	// List of errors that were encountered while loading the trace by the TS
	// code. These are on top of traceInfo.importErrors, which is a summary of
	// what TraceProcessor reports on the stats table at import time.
	readonly loadingErrors: string[] = [];

	constructor(gctx: AppContext, engine: EngineBase, traceInfo: TraceInfoImpl) {
	this.appCtx = gctx;
	this.engine = engine;
	this.trash.use(engine);
	this.traceInfo = traceInfo;
	this.timeline = new TimelineImpl(traceInfo);

	this.scrollHelper = new ScrollHelper(
	this.traceInfo,
	this.timeline,
	this.workspaceMgr.currentWorkspace,
	this.trackMgr,
	);

	this.selectionMgr = new SelectionManagerImpl(
	this.engine,
	this.trackMgr,
	this.noteMgr,
	this.scrollHelper,
	this.onSelectionChange.bind(this),
	);

	this.noteMgr.onNoteDeleted = (noteId) => {
	if (
	this.selectionMgr.selection.kind === 'note' &&
	this.selectionMgr.selection.id === noteId
	) {
	this.selectionMgr.clear();
	}
	};

	this.pivotTableMgr = new PivotTableManager(
	engine.getProxy('PivotTableManager'),
	);

	this.flowMgr = new FlowManager(
	engine.getProxy('FlowManager'),
	this.trackMgr,
	this.selectionMgr,
	);

	this.searchMgr = new SearchManagerImpl({
	timeline: this.timeline,
	trackManager: this.trackMgr,
	engine: this.engine,
	workspace: this.workspaceMgr.currentWorkspace,
	onResultStep: this.onResultStep.bind(this),
	});
	}

	// This method wires up changes to selection to side effects on search and
	// tabs. This is to avoid entangling too many dependencies between managers.
	private onSelectionChange(selection: Selection, opts: SelectionOpts) {
	const {clearSearch = true, switchToCurrentSelectionTab = true} = opts;
	if (clearSearch) {
	this.searchMgr.reset();
	}
	if (switchToCurrentSelectionTab && selection.kind !== 'empty') {
	this.tabMgr.showCurrentSelectionTab();
	}

	if (selection.kind === 'area') {
	this.pivotTableMgr.setSelectionArea(selection);
	}

	this.flowMgr.updateFlows(selection);
	}

	private onResultStep(searchResult: SearchResult) {
	this.selectionMgr.selectSearchResult(searchResult);
	}

	// Gets or creates an instance of TraceImpl backed by the current TraceContext
	// for the given plugin.
	forPlugin(pluginId: string) {
	return getOrCreate(this.pluginInstances, pluginId, () => {
	const appForPlugin = this.appCtx.forPlugin(pluginId);
	return new TraceImpl(appForPlugin, this);
	});
	}

	// Called by AppContext.closeCurrentTrace().
	[Symbol.dispose]() {
	this.trash.dispose();
	}
	}

	/**
	* This implementation provides the plugin access to trace related resources,
	* such as the engine and the store. This exists for the whole duration a plugin
	* is active AND a trace is loaded.
	* There are N+1 instances of this for each trace, one for each plugin plus one
	* for the core.
	*/
	export class TraceImpl implements Trace {
	private readonly appImpl: AppImpl;
	private readonly traceCtx: TraceContext;

	// This is not the original Engine base, rather an EngineProxy based on the
	// same engineBase.
	private readonly engineProxy: EngineProxy;
	private readonly trackMgrProxy: TrackManagerImpl;
	private readonly commandMgrProxy: CommandManagerImpl;
	private readonly sidebarProxy: SidebarManagerImpl;
	private readonly pageMgrProxy: PageManagerImpl;

	// This is called by TraceController when loading a new trace, soon after the
	// engine has been set up. It obtains a new TraceImpl for the core. From that
	// we can fork sibling instances (i.e. bound to the same TraceContext) for
	// the various plugins.
	static createInstanceForCore(
	appImpl: AppImpl,
	engine: EngineBase,
	traceInfo: TraceInfoImpl,
	): TraceImpl {
	const traceCtx = new TraceContext(
	appImpl.__appCtxForTrace,
	engine,
	traceInfo,
	);
	return traceCtx.forPlugin(CORE_PLUGIN_ID);
	}

	// Only called by TraceContext.forPlugin().
	constructor(appImpl: AppImpl, ctx: TraceContext) {
	const pluginId = appImpl.pluginId;
	this.appImpl = appImpl;
	this.traceCtx = ctx;
	const traceUnloadTrash = ctx.trash;

	// Invalidate all the engine proxies when the TraceContext is destroyed.
	this.engineProxy = ctx.engine.getProxy(pluginId);
	traceUnloadTrash.use(this.engineProxy);

	// Intercept the registerTrack() method to inject the pluginId into tracks.
	this.trackMgrProxy = createProxy(ctx.trackMgr, {
	registerTrack(trackDesc: TrackDescriptor): Disposable {
	return ctx.trackMgr.registerTrack({...trackDesc, pluginId});
	},
	});

	// CommandManager is global. Here we intercept the registerCommand() because
	// we want any commands registered via the Trace interface to be
	// unregistered when the trace unloads (before a new trace is loaded) to
	// avoid ending up with duplicate commands.
	this.commandMgrProxy = createProxy(ctx.appCtx.commandMgr, {
	registerCommand(cmd: Command): Disposable {
	const disposable = appImpl.commands.registerCommand(cmd);
	traceUnloadTrash.use(disposable);
	return disposable;
	},
	});

	// Likewise, remove all trace-scoped sidebar entries when the trace unloads.
	this.sidebarProxy = createProxy(ctx.appCtx.sidebarMgr, {
	addMenuItem(menuItem: SidebarMenuItem): Disposable {
	const disposable = appImpl.sidebar.addMenuItem(menuItem);
	traceUnloadTrash.use(disposable);
	return disposable;
	},
	});

	this.pageMgrProxy = createProxy(ctx.appCtx.pageMgr, {
	registerPage(pageHandler: PageHandler): Disposable {
	const disposable = appImpl.pages.registerPage({
	...pageHandler,
	pluginId: appImpl.pluginId,
	});
	traceUnloadTrash.use(disposable);
	return disposable;
	},
	});

	// TODO(primiano): remove this injection once we plumb Trace everywhere.
	setScrollToFunction((x: ScrollToArgs) => ctx.scrollHelper.scrollTo(x));
	}

	scrollTo(where: ScrollToArgs): void {
	this.traceCtx.scrollHelper.scrollTo(where);
	}

	// Creates an instance of TraceImpl backed by the same TraceContext for
	// another plugin. This is effectively a way to "fork" the core instance and
	// create the N instances for plugins.
	forkForPlugin(pluginId: string) {
	return this.traceCtx.forPlugin(pluginId);
	}

	mountStore<T>(migrate: Migrate<T>): Store<T> {
	return this.traceCtx.pluginSerializableState.createSubStore(
	[this.pluginId],
	migrate,
	);
	}

	getPluginStoreForSerialization() {
	return this.traceCtx.pluginSerializableState;
	}

	async getTraceFile(): Promise<Blob> {
	const src = this.traceInfo.source;
	if (this.traceInfo.downloadable) {
	if (src.type === 'ARRAY_BUFFER') {
	return new Blob([src.buffer]);
	} else if (src.type === 'FILE') {
	return src.file;
	} else if (src.type === 'URL') {
	return await fetchWithProgress(src.url, (progressPercent: number) =>
	this.omnibox.showStatusMessage(
	`Downloading trace ${progressPercent}%`,
	),
	);
	}
	}
	// Not available in HTTP+RPC mode. Rather than propagating an undefined,
	// show a graceful error (the ERR:trace_src will be intercepted by
	// error_dialog.ts). We expect all users of this feature to not be able to
	// do anything useful if we returned undefined (other than showing the same
	// dialog).
	// The caller was supposed to check that traceInfo.downloadable === true
	// before calling this. Throwing while downloadable is true is a bug.
	throw new Error(`Cannot getTraceFile(${src.type})`);
	}

	get openerPluginArgs(): {[key: string]: unknown} \| undefined {
	const traceSource = this.traceCtx.traceInfo.source;
	if (traceSource.type !== 'ARRAY_BUFFER') {
	return undefined;
	}
	const pluginArgs = traceSource.pluginArgs;
	return (pluginArgs ?? {})[this.pluginId];
	}

	get trace() {
	return this;
	}

	get engine() {
	return this.engineProxy;
	}

	get timeline() {
	return this.traceCtx.timeline;
	}

	get tracks() {
	return this.trackMgrProxy;
	}

	get tabs() {
	return this.traceCtx.tabMgr;
	}

	get workspace() {
	return this.traceCtx.workspaceMgr.currentWorkspace;
	}

	get workspaces() {
	return this.traceCtx.workspaceMgr;
	}

	get search() {
	return this.traceCtx.searchMgr;
	}

	get selection() {
	return this.traceCtx.selectionMgr;
	}

	get traceInfo(): TraceInfoImpl {
	return this.traceCtx.traceInfo;
	}

	get notes() {
	return this.traceCtx.noteMgr;
	}

	get pivotTable() {
	return this.traceCtx.pivotTableMgr;
	}

	get flows() {
	return this.traceCtx.flowMgr;
	}

	get loadingErrors(): ReadonlyArray<string> {
	return this.traceCtx.loadingErrors;
	}

	addLoadingError(err: string) {
	this.traceCtx.loadingErrors.push(err);
	}

	// App interface implementation.

	get pluginId(): string {
	return this.appImpl.pluginId;
	}

	get commands(): CommandManagerImpl {
	return this.commandMgrProxy;
	}

	get sidebar(): SidebarManagerImpl {
	return this.sidebarProxy;
	}

	get pages(): PageManager {
	return this.pageMgrProxy;
	}

	get omnibox(): OmniboxManagerImpl {
	return this.appImpl.omnibox;
	}

	get plugins(): PluginManagerImpl {
	return this.appImpl.plugins;
	}

	get analytics(): Analytics {
	return this.appImpl.analytics;
	}

	get initialRouteArgs(): RouteArgs {
	return this.appImpl.initialRouteArgs;
	}

	get featureFlags(): FeatureFlagManager {
	return {
	register: (settings: FlagSettings) => featureFlags.register(settings),
	};
	}

	scheduleFullRedraw(): void {
	this.appImpl.scheduleFullRedraw();
	}

	navigate(newHash: string): void {
	this.appImpl.navigate(newHash);
	}

	openTraceFromFile(file: File): void {
	this.appImpl.openTraceFromFile(file);
	}

	openTraceFromUrl(url: string, serializedAppState?: SerializedAppState) {
	this.appImpl.openTraceFromUrl(url, serializedAppState);
	}

	openTraceFromBuffer(args: PostedTrace): void {
	this.appImpl.openTraceFromBuffer(args);
	}

	addEventListener<T extends keyof EventListeners>(
	event: T,
	callback: EventListeners[T],
	): void {
	const listeners = getOrCreate(
	this.traceCtx.eventListeners,
	event,
	() => [],
	);
	listeners.push(callback);
	}

	getEventListeners<T extends keyof EventListeners>(
	event: T,
	): ReadonlyArray<EventListeners[T]> {
	const listeners = this.traceCtx.eventListeners.get(event);
	if (listeners) {
	return listeners as ReadonlyArray<EventListeners[T]>;
	} else {
	return [];
	}
	}

	get perfDebugging(): PerfManager {
	return this.appImpl.perfDebugging;
	}

	get trash(): DisposableStack {
	return this.traceCtx.trash;
	}

	// Nothing other than AppImpl should ever refer to this, hence the __ name.
	get __traceCtxForApp() {
	return this.traceCtx;
	}
	}

	// A convenience interface to inject the App in Mithril components.
	export interface TraceImplAttrs {
	trace: TraceImpl;
	}

	export interface OptionalTraceImplAttrs {
	trace?: TraceImpl;
	}