ui/src/plugins/dev.perfetto.CpuSlices/cpu_slice_track.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 {BigintMath as BIMath} from '../../base/bigint_math';
 import {search, searchEq, searchSegment} from '../../base/binary_search';
 import {assertExists, assertTrue} from '../../base/logging';
 import {Duration, duration, Time, time} from '../../base/time';
 import {
   drawDoubleHeadedArrow,
   drawIncompleteSlice,
   drawTrackHoverTooltip,
 } from '../../base/canvas_utils';
 import {cropText} from '../../base/string_utils';
 import {Color} from '../../public/color';
 import {colorForThread} from '../../public/lib/colorizer';
 import {TrackData} from '../../common/track_data';
 import {TimelineFetcher} from '../../common/track_helper';
 import {checkerboardExcept} from '../../frontend/checkerboard';
 import {Point2D} from '../../base/geom';
 import {Track} from '../../public/track';
 import {LONG, NUM} from '../../trace_processor/query_result';
 import {uuidv4Sql} from '../../base/uuid';
 import {TrackMouseEvent, TrackRenderContext} from '../../public/track';
 import {TrackEventDetails} from '../../public/selection';
 import {asSchedSqlId} from '../../trace_processor/sql_utils/core_types';
 import {
   getSched,
   getSchedWakeupInfo,
 } from '../../trace_processor/sql_utils/sched';
 import {SchedSliceDetailsPanel} from './sched_details_tab';
 import {Trace} from '../../public/trace';
 import {exists} from '../../base/utils';
 import {ThreadMap} from '../dev.perfetto.Thread/threads';
 import {Dataset, SourceDataset} from '../../trace_processor/dataset';

 export interface Data extends TrackData {
   // Slices are stored in a columnar fashion. All fields have the same length.
   ids: Float64Array;
   startQs: BigInt64Array;
   endQs: BigInt64Array;
   utids: Uint32Array;
   flags: Uint8Array;
   lastRowId: number;
 }

 const MARGIN_TOP = 3;
 const RECT_HEIGHT = 24;
 const TRACK_HEIGHT = MARGIN_TOP * 2 + RECT_HEIGHT;

 const CPU_SLICE_FLAGS_INCOMPLETE = 1;
 const CPU_SLICE_FLAGS_REALTIME = 2;

 export class CpuSliceTrack implements Track {
   private mousePos?: Point2D;
   private utidHoveredInThisTrack?: number;
   private fetcher = new TimelineFetcher<Data>(this.onBoundsChange.bind(this));

   private lastRowId = -1;
   private trackUuid = uuidv4Sql();

   constructor(
     private readonly trace: Trace,
     private readonly uri: string,
     private readonly cpu: number,
     private readonly threads: ThreadMap,
   ) {}

   async onCreate() {
     await this.trace.engine.query(`
       create virtual table cpu_slice_${this.trackUuid}
       using __intrinsic_slice_mipmap((
         select
           id,
           ts,
           iif(dur = -1, lead(ts, 1, trace_end()) over (order by ts) - ts, dur),
           0 as depth
         from sched
         where cpu = ${this.cpu} and utid != 0
       ));
     `);
     const it = await this.trace.engine.query(`
       select coalesce(max(id), -1) as lastRowId
       from sched
       where cpu = ${this.cpu} and utid != 0
     `);
     this.lastRowId = it.firstRow({lastRowId: NUM}).lastRowId;
   }

   getDataset(): Dataset | undefined {
     return new SourceDataset({
       src: 'select id, ts, dur, cpu from sched where utid != 0',
       schema: {
         id: NUM,
         ts: LONG,
         dur: LONG,
       },
       filter: {
         col: 'cpu',
         eq: this.cpu,
       },
     });
   }

   async onUpdate({
     visibleWindow,
     resolution,
   }: TrackRenderContext): Promise<void> {
     await this.fetcher.requestData(visibleWindow.toTimeSpan(), resolution);
   }

   async onBoundsChange(
     start: time,
     end: time,
     resolution: duration,
   ): Promise<Data> {
     assertTrue(BIMath.popcount(resolution) === 1, `${resolution} not pow of 2`);

     const queryRes = await this.trace.engine.query(`
       select
         (z.ts / ${resolution}) * ${resolution} as tsQ,
         (((z.ts + z.dur) / ${resolution}) + 1) * ${resolution} as tsEndQ,
         s.utid,
         s.id,
         s.dur = -1 as isIncomplete,
         ifnull(s.priority < 100, 0) as isRealtime
       from cpu_slice_${this.trackUuid}(${start}, ${end}, ${resolution}) z
       cross join sched s using (id)
     `);

     const numRows = queryRes.numRows();
     const slices: Data = {
       start,
       end,
       resolution,
       length: numRows,
       lastRowId: this.lastRowId,
       ids: new Float64Array(numRows),
       startQs: new BigInt64Array(numRows),
       endQs: new BigInt64Array(numRows),
       utids: new Uint32Array(numRows),
       flags: new Uint8Array(numRows),
     };

     const it = queryRes.iter({
       tsQ: LONG,
       tsEndQ: LONG,
       utid: NUM,
       id: NUM,
       isIncomplete: NUM,
       isRealtime: NUM,
     });
     for (let row = 0; it.valid(); it.next(), row++) {
       slices.startQs[row] = it.tsQ;
       slices.endQs[row] = it.tsEndQ;
       slices.utids[row] = it.utid;
       slices.ids[row] = it.id;

       slices.flags[row] = 0;
       if (it.isIncomplete) {
         slices.flags[row] |= CPU_SLICE_FLAGS_INCOMPLETE;
       }
       if (it.isRealtime) {
         slices.flags[row] |= CPU_SLICE_FLAGS_REALTIME;
       }
     }
     return slices;
   }

   async onDestroy() {
     await this.trace.engine.tryQuery(
       `drop table if exists cpu_slice_${this.trackUuid}`,
     );
     this.fetcher[Symbol.dispose]();
   }

   getHeight(): number {
     return TRACK_HEIGHT;
   }

   render(trackCtx: TrackRenderContext): void {
     const {ctx, size, timescale} = trackCtx;

     // TODO: fonts and colors should come from the CSS and not hardcoded here.
     const data = this.fetcher.data;

     if (data === undefined) return; // Can't possibly draw anything.

     // If the cached trace slices don't fully cover the visible time range,
     // show a gray rectangle with a "Loading..." label.
     checkerboardExcept(
       ctx,
       this.getHeight(),
       0,
       size.width,
       timescale.timeToPx(data.start),
       timescale.timeToPx(data.end),
     );

     this.renderSlices(trackCtx, data);
   }

   renderSlices(
     {ctx, timescale, size, visibleWindow}: TrackRenderContext,
     data: Data,
   ): void {
     assertTrue(data.startQs.length === data.endQs.length);
     assertTrue(data.startQs.length === data.utids.length);

     const visWindowEndPx = size.width;

     ctx.textAlign = 'center';
     ctx.font = '12px Roboto Condensed';
     const charWidth = ctx.measureText('dbpqaouk').width / 8;

     const timespan = visibleWindow.toTimeSpan();

     const startTime = timespan.start;
     const endTime = timespan.end;

     const rawStartIdx = data.endQs.findIndex((end) => end >= startTime);
     const startIdx = rawStartIdx === -1 ? 0 : rawStartIdx;

     const [, rawEndIdx] = searchSegment(data.startQs, endTime);
     const endIdx = rawEndIdx === -1 ? data.startQs.length : rawEndIdx;

     for (let i = startIdx; i < endIdx; i++) {
       const tStart = Time.fromRaw(data.startQs[i]);
       let tEnd = Time.fromRaw(data.endQs[i]);
       const utid = data.utids[i];

       // If the last slice is incomplete, it should end with the end of the
       // window, else it might spill over the window and the end would not be
       // visible as a zigzag line.
       if (
         data.ids[i] === data.lastRowId &&
         data.flags[i] & CPU_SLICE_FLAGS_INCOMPLETE
       ) {
         tEnd = endTime;
       }
       const rectStart = timescale.timeToPx(tStart);
       const rectEnd = timescale.timeToPx(tEnd);
       const rectWidth = Math.max(1, rectEnd - rectStart);

       const threadInfo = this.threads.get(utid);
       // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
       const pid = threadInfo && threadInfo.pid ? threadInfo.pid : -1;

       const isHovering = this.trace.timeline.hoveredUtid !== undefined;
       const isThreadHovered = this.trace.timeline.hoveredUtid === utid;
       const isProcessHovered = this.trace.timeline.hoveredPid === pid;
       const colorScheme = colorForThread(threadInfo);
       let color: Color;
       let textColor: Color;
       if (isHovering && !isThreadHovered) {
         if (!isProcessHovered) {
           color = colorScheme.disabled;
           textColor = colorScheme.textDisabled;
         } else {
           color = colorScheme.variant;
           textColor = colorScheme.textVariant;
         }
       } else {
         color = colorScheme.base;
         textColor = colorScheme.textBase;
       }
       ctx.fillStyle = color.cssString;

       if (data.flags[i] & CPU_SLICE_FLAGS_INCOMPLETE) {
         drawIncompleteSlice(ctx, rectStart, MARGIN_TOP, rectWidth, RECT_HEIGHT);
       } else {
         ctx.fillRect(rectStart, MARGIN_TOP, rectWidth, RECT_HEIGHT);
       }

       // Don't render text when we have less than 5px to play with.
       if (rectWidth < 5) continue;

       // Stylize real-time threads. We don't do it when zoomed out as the
       // fillRect is expensive.
       if (data.flags[i] & CPU_SLICE_FLAGS_REALTIME) {
         ctx.fillStyle = getHatchedPattern(ctx);
         ctx.fillRect(rectStart, MARGIN_TOP, rectWidth, RECT_HEIGHT);
       }

       // TODO: consider de-duplicating this code with the copied one from
       // chrome_slices/frontend.ts.
       let title = `[utid:${utid}]`;
       let subTitle = '';
       if (threadInfo) {
         if (threadInfo.pid !== undefined && threadInfo.pid !== 0) {
           let procName = threadInfo.procName ?? '';
           if (procName.startsWith('/')) {
             // Remove folder paths from name
             procName = procName.substring(procName.lastIndexOf('/') + 1);
           }
           title = `${procName} [${threadInfo.pid}]`;
           subTitle = `${threadInfo.threadName} [${threadInfo.tid}]`;
         } else {
           title = `${threadInfo.threadName} [${threadInfo.tid}]`;
         }
       }

       if (data.flags[i] & CPU_SLICE_FLAGS_REALTIME) {
         subTitle = subTitle + ' (RT)';
       }

       const right = Math.min(visWindowEndPx, rectEnd);
       const left = Math.max(rectStart, 0);
       const visibleWidth = Math.max(right - left, 1);
       title = cropText(title, charWidth, visibleWidth);
       subTitle = cropText(subTitle, charWidth, visibleWidth);
       const rectXCenter = left + visibleWidth / 2;
       ctx.fillStyle = textColor.cssString;
       ctx.font = '12px Roboto Condensed';
       ctx.fillText(title, rectXCenter, MARGIN_TOP + RECT_HEIGHT / 2 - 1);
       ctx.fillStyle = textColor.setAlpha(0.6).cssString;
       ctx.font = '10px Roboto Condensed';
       ctx.fillText(subTitle, rectXCenter, MARGIN_TOP + RECT_HEIGHT / 2 + 9);
     }

     const selection = this.trace.selection.selection;
     if (selection.kind === 'track_event') {
       if (selection.trackUri === this.uri) {
         const [startIndex, endIndex] = searchEq(data.ids, selection.eventId);
         if (startIndex !== endIndex) {
           const tStart = Time.fromRaw(data.startQs[startIndex]);
           const tEnd = Time.fromRaw(data.endQs[startIndex]);
           const utid = data.utids[startIndex];
           const color = colorForThread(this.threads.get(utid));
           const rectStart = timescale.timeToPx(tStart);
           const rectEnd = timescale.timeToPx(tEnd);
           const rectWidth = Math.max(1, rectEnd - rectStart);

           // Draw a rectangle around the slice that is currently selected.
           ctx.strokeStyle = color.base.setHSL({l: 30}).cssString;
           ctx.beginPath();
           ctx.lineWidth = 3;
           ctx.strokeRect(
             rectStart,
             MARGIN_TOP - 1.5,
             rectWidth,
             RECT_HEIGHT + 3,
           );
           ctx.closePath();
           // Draw arrow from wakeup time of current slice.
           if (selection.wakeupTs) {
             const wakeupPos = timescale.timeToPx(selection.wakeupTs);
             const latencyWidth = rectStart - wakeupPos;
             drawDoubleHeadedArrow(
               ctx,
               wakeupPos,
               MARGIN_TOP + RECT_HEIGHT,
               latencyWidth,
               latencyWidth >= 20,
             );
             // Latency time with a white semi-transparent background.
             const latency = tStart - selection.wakeupTs;
             const displayText = Duration.humanise(latency);
             const measured = ctx.measureText(displayText);
             if (latencyWidth >= measured.width + 2) {
               ctx.fillStyle = 'rgba(255,255,255,0.7)';
               ctx.fillRect(
                 wakeupPos + latencyWidth / 2 - measured.width / 2 - 1,
                 MARGIN_TOP + RECT_HEIGHT - 12,
                 measured.width + 2,
                 11,
               );
               ctx.textBaseline = 'bottom';
               ctx.fillStyle = 'black';
               ctx.fillText(
                 displayText,
                 wakeupPos + latencyWidth / 2,
                 MARGIN_TOP + RECT_HEIGHT - 1,
               );
             }
           }
         }
       }

       // Draw diamond if the track being drawn is the cpu of the waker.
       if (this.cpu === selection.wakerCpu && selection.wakeupTs) {
         const wakeupPos = Math.floor(timescale.timeToPx(selection.wakeupTs));
         ctx.beginPath();
         ctx.moveTo(wakeupPos, MARGIN_TOP + RECT_HEIGHT / 2 + 8);
         ctx.fillStyle = 'black';
         ctx.lineTo(wakeupPos + 6, MARGIN_TOP + RECT_HEIGHT / 2);
         ctx.lineTo(wakeupPos, MARGIN_TOP + RECT_HEIGHT / 2 - 8);
         ctx.lineTo(wakeupPos - 6, MARGIN_TOP + RECT_HEIGHT / 2);
         ctx.fill();
         ctx.closePath();
       }

       if (this.utidHoveredInThisTrack !== undefined) {
         const hoveredThread = this.threads.get(this.utidHoveredInThisTrack);
         if (hoveredThread && this.mousePos !== undefined) {
           const tidText = `T: ${hoveredThread.threadName}
           [${hoveredThread.tid}]`;
           // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
           if (hoveredThread.pid) {
             const pidText = `P: ${hoveredThread.procName}
             [${hoveredThread.pid}]`;
             drawTrackHoverTooltip(ctx, this.mousePos, size, pidText, tidText);
           } else {
             drawTrackHoverTooltip(ctx, this.mousePos, size, tidText);
           }
         }
       }
     }
   }

   onMouseMove({x, y, timescale}: TrackMouseEvent) {
     const data = this.fetcher.data;
     this.mousePos = {x, y};
     if (data === undefined) return;
     if (y < MARGIN_TOP || y > MARGIN_TOP + RECT_HEIGHT) {
       this.utidHoveredInThisTrack = undefined;
       this.trace.timeline.hoveredUtid = undefined;
       this.trace.timeline.hoveredPid = undefined;
       return;
     }
     const t = timescale.pxToHpTime(x);
     let hoveredUtid = undefined;

     for (let i = 0; i < data.startQs.length; i++) {
       const tStart = Time.fromRaw(data.startQs[i]);
       const tEnd = Time.fromRaw(data.endQs[i]);
       const utid = data.utids[i];
       if (t.gte(tStart) && t.lt(tEnd)) {
         hoveredUtid = utid;
         break;
       }
     }
     this.utidHoveredInThisTrack = hoveredUtid;
     const threadInfo = exists(hoveredUtid) && this.threads.get(hoveredUtid);
     // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
     const hoveredPid = threadInfo ? (threadInfo.pid ? threadInfo.pid : -1) : -1;
     this.trace.timeline.hoveredUtid = hoveredUtid;
     this.trace.timeline.hoveredPid = hoveredPid;
   }

   onMouseOut() {
     this.utidHoveredInThisTrack = -1;
     this.trace.timeline.hoveredUtid = undefined;
     this.trace.timeline.hoveredPid = undefined;
     this.mousePos = undefined;
   }

   onMouseClick({x, timescale}: TrackMouseEvent) {
     const data = this.fetcher.data;
     if (data === undefined) return false;
     const time = timescale.pxToHpTime(x);
     const index = search(data.startQs, time.toTime());
     const id = index === -1 ? undefined : data.ids[index];
     // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
     if (!id || this.utidHoveredInThisTrack === -1) return false;

     this.trace.selection.selectTrackEvent(this.uri, id);
     return true;
   }

   async getSelectionDetails?(
     eventId: number,
   ): Promise<TrackEventDetails | undefined> {
     const sched = await getSched(this.trace.engine, asSchedSqlId(eventId));
     if (sched === undefined) {
       return undefined;
     }
     const wakeup = await getSchedWakeupInfo(this.trace.engine, sched);
     return {
       ts: sched.ts,
       dur: sched.dur,
       wakeupTs: wakeup?.wakeupTs,
       wakerCpu: wakeup?.wakerCpu,
     };
   }

   detailsPanel() {
     return new SchedSliceDetailsPanel(this.trace, this.threads);
   }
 }

 // Creates a diagonal hatched pattern to be used for distinguishing slices with
 // real-time priorities. The pattern is created once as an offscreen canvas and
 // is kept cached inside the Context2D of the main canvas, without making
 // assumptions on the lifetime of the main canvas.
 function getHatchedPattern(mainCtx: CanvasRenderingContext2D): CanvasPattern {
   const mctx = mainCtx as CanvasRenderingContext2D & {
     sliceHatchedPattern?: CanvasPattern;
   };
   if (mctx.sliceHatchedPattern !== undefined) return mctx.sliceHatchedPattern;
   const canvas = document.createElement('canvas');
   const SIZE = 8;
   canvas.width = canvas.height = SIZE;
   const ctx = assertExists(canvas.getContext('2d'));
   ctx.strokeStyle = 'rgba(255,255,255,0.3)';
   ctx.beginPath();
   ctx.lineWidth = 1;
   ctx.moveTo(0, SIZE);
   ctx.lineTo(SIZE, 0);
   ctx.stroke();
   mctx.sliceHatchedPattern = assertExists(mctx.createPattern(canvas, 'repeat'));
   return mctx.sliceHatchedPattern;
 }
	// 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 {BigintMath as BIMath} from '../../base/bigint_math';
	import {search, searchEq, searchSegment} from '../../base/binary_search';
	import {assertExists, assertTrue} from '../../base/logging';
	import {Duration, duration, Time, time} from '../../base/time';
	import {
	drawDoubleHeadedArrow,
	drawIncompleteSlice,
	drawTrackHoverTooltip,
	} from '../../base/canvas_utils';
	import {cropText} from '../../base/string_utils';
	import {Color} from '../../public/color';
	import {colorForThread} from '../../public/lib/colorizer';
	import {TrackData} from '../../common/track_data';
	import {TimelineFetcher} from '../../common/track_helper';
	import {checkerboardExcept} from '../../frontend/checkerboard';
	import {Point2D} from '../../base/geom';
	import {Track} from '../../public/track';
	import {LONG, NUM} from '../../trace_processor/query_result';
	import {uuidv4Sql} from '../../base/uuid';
	import {TrackMouseEvent, TrackRenderContext} from '../../public/track';
	import {TrackEventDetails} from '../../public/selection';
	import {asSchedSqlId} from '../../trace_processor/sql_utils/core_types';
	import {
	getSched,
	getSchedWakeupInfo,
	} from '../../trace_processor/sql_utils/sched';
	import {SchedSliceDetailsPanel} from './sched_details_tab';
	import {Trace} from '../../public/trace';
	import {exists} from '../../base/utils';
	import {ThreadMap} from '../dev.perfetto.Thread/threads';
	import {Dataset, SourceDataset} from '../../trace_processor/dataset';

	export interface Data extends TrackData {
	// Slices are stored in a columnar fashion. All fields have the same length.
	ids: Float64Array;
	startQs: BigInt64Array;
	endQs: BigInt64Array;
	utids: Uint32Array;
	flags: Uint8Array;
	lastRowId: number;
	}

	const MARGIN_TOP = 3;
	const RECT_HEIGHT = 24;
	const TRACK_HEIGHT = MARGIN_TOP * 2 + RECT_HEIGHT;

	const CPU_SLICE_FLAGS_INCOMPLETE = 1;
	const CPU_SLICE_FLAGS_REALTIME = 2;

	export class CpuSliceTrack implements Track {
	private mousePos?: Point2D;
	private utidHoveredInThisTrack?: number;
	private fetcher = new TimelineFetcher<Data>(this.onBoundsChange.bind(this));

	private lastRowId = -1;
	private trackUuid = uuidv4Sql();

	constructor(
	private readonly trace: Trace,
	private readonly uri: string,
	private readonly cpu: number,
	private readonly threads: ThreadMap,
	) {}

	async onCreate() {
	await this.trace.engine.query(`
	create virtual table cpu_slice_${this.trackUuid}
	using __intrinsic_slice_mipmap((
	select
	id,
	ts,
	iif(dur = -1, lead(ts, 1, trace_end()) over (order by ts) - ts, dur),
	0 as depth
	from sched
	where cpu = ${this.cpu} and utid != 0
	));
	`);
	const it = await this.trace.engine.query(`
	select coalesce(max(id), -1) as lastRowId
	from sched
	where cpu = ${this.cpu} and utid != 0
	`);
	this.lastRowId = it.firstRow({lastRowId: NUM}).lastRowId;
	}

	getDataset(): Dataset \| undefined {
	return new SourceDataset({
	src: 'select id, ts, dur, cpu from sched where utid != 0',
	schema: {
	id: NUM,
	ts: LONG,
	dur: LONG,
	},
	filter: {
	col: 'cpu',
	eq: this.cpu,
	},
	});
	}

	async onUpdate({
	visibleWindow,
	resolution,
	}: TrackRenderContext): Promise<void> {
	await this.fetcher.requestData(visibleWindow.toTimeSpan(), resolution);
	}

	async onBoundsChange(
	start: time,
	end: time,
	resolution: duration,
	): Promise<Data> {
	assertTrue(BIMath.popcount(resolution) === 1, `${resolution} not pow of 2`);

	const queryRes = await this.trace.engine.query(`
	select
	(z.ts / ${resolution}) * ${resolution} as tsQ,
	(((z.ts + z.dur) / ${resolution}) + 1) * ${resolution} as tsEndQ,
	s.utid,
	s.id,
	s.dur = -1 as isIncomplete,
	ifnull(s.priority < 100, 0) as isRealtime
	from cpu_slice_${this.trackUuid}(${start}, ${end}, ${resolution}) z
	cross join sched s using (id)
	`);

	const numRows = queryRes.numRows();
	const slices: Data = {
	start,
	end,
	resolution,
	length: numRows,
	lastRowId: this.lastRowId,
	ids: new Float64Array(numRows),
	startQs: new BigInt64Array(numRows),
	endQs: new BigInt64Array(numRows),
	utids: new Uint32Array(numRows),
	flags: new Uint8Array(numRows),
	};

	const it = queryRes.iter({
	tsQ: LONG,
	tsEndQ: LONG,
	utid: NUM,
	id: NUM,
	isIncomplete: NUM,
	isRealtime: NUM,
	});
	for (let row = 0; it.valid(); it.next(), row++) {
	slices.startQs[row] = it.tsQ;
	slices.endQs[row] = it.tsEndQ;
	slices.utids[row] = it.utid;
	slices.ids[row] = it.id;

	slices.flags[row] = 0;
	if (it.isIncomplete) {
	slices.flags[row] \|= CPU_SLICE_FLAGS_INCOMPLETE;
	}
	if (it.isRealtime) {
	slices.flags[row] \|= CPU_SLICE_FLAGS_REALTIME;
	}
	}
	return slices;
	}

	async onDestroy() {
	await this.trace.engine.tryQuery(
	`drop table if exists cpu_slice_${this.trackUuid}`,
	);
	this.fetcher[Symbol.dispose]();
	}

	getHeight(): number {
	return TRACK_HEIGHT;
	}

	render(trackCtx: TrackRenderContext): void {
	const {ctx, size, timescale} = trackCtx;

	// TODO: fonts and colors should come from the CSS and not hardcoded here.
	const data = this.fetcher.data;

	if (data === undefined) return; // Can't possibly draw anything.

	// If the cached trace slices don't fully cover the visible time range,
	// show a gray rectangle with a "Loading..." label.
	checkerboardExcept(
	ctx,
	this.getHeight(),
	0,
	size.width,
	timescale.timeToPx(data.start),
	timescale.timeToPx(data.end),
	);

	this.renderSlices(trackCtx, data);
	}

	renderSlices(
	{ctx, timescale, size, visibleWindow}: TrackRenderContext,
	data: Data,
	): void {
	assertTrue(data.startQs.length === data.endQs.length);
	assertTrue(data.startQs.length === data.utids.length);

	const visWindowEndPx = size.width;

	ctx.textAlign = 'center';
	ctx.font = '12px Roboto Condensed';
	const charWidth = ctx.measureText('dbpqaouk').width / 8;

	const timespan = visibleWindow.toTimeSpan();

	const startTime = timespan.start;
	const endTime = timespan.end;

	const rawStartIdx = data.endQs.findIndex((end) => end >= startTime);
	const startIdx = rawStartIdx === -1 ? 0 : rawStartIdx;

	const [, rawEndIdx] = searchSegment(data.startQs, endTime);
	const endIdx = rawEndIdx === -1 ? data.startQs.length : rawEndIdx;

	for (let i = startIdx; i < endIdx; i++) {
	const tStart = Time.fromRaw(data.startQs[i]);
	let tEnd = Time.fromRaw(data.endQs[i]);
	const utid = data.utids[i];

	// If the last slice is incomplete, it should end with the end of the
	// window, else it might spill over the window and the end would not be
	// visible as a zigzag line.
	if (
	data.ids[i] === data.lastRowId &&
	data.flags[i] & CPU_SLICE_FLAGS_INCOMPLETE
	) {
	tEnd = endTime;
	}
	const rectStart = timescale.timeToPx(tStart);
	const rectEnd = timescale.timeToPx(tEnd);
	const rectWidth = Math.max(1, rectEnd - rectStart);

	const threadInfo = this.threads.get(utid);
	// eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
	const pid = threadInfo && threadInfo.pid ? threadInfo.pid : -1;

	const isHovering = this.trace.timeline.hoveredUtid !== undefined;
	const isThreadHovered = this.trace.timeline.hoveredUtid === utid;
	const isProcessHovered = this.trace.timeline.hoveredPid === pid;
	const colorScheme = colorForThread(threadInfo);
	let color: Color;
	let textColor: Color;
	if (isHovering && !isThreadHovered) {
	if (!isProcessHovered) {
	color = colorScheme.disabled;
	textColor = colorScheme.textDisabled;
	} else {
	color = colorScheme.variant;
	textColor = colorScheme.textVariant;
	}
	} else {
	color = colorScheme.base;
	textColor = colorScheme.textBase;
	}
	ctx.fillStyle = color.cssString;

	if (data.flags[i] & CPU_SLICE_FLAGS_INCOMPLETE) {
	drawIncompleteSlice(ctx, rectStart, MARGIN_TOP, rectWidth, RECT_HEIGHT);
	} else {
	ctx.fillRect(rectStart, MARGIN_TOP, rectWidth, RECT_HEIGHT);
	}

	// Don't render text when we have less than 5px to play with.
	if (rectWidth < 5) continue;

	// Stylize real-time threads. We don't do it when zoomed out as the
	// fillRect is expensive.
	if (data.flags[i] & CPU_SLICE_FLAGS_REALTIME) {
	ctx.fillStyle = getHatchedPattern(ctx);
	ctx.fillRect(rectStart, MARGIN_TOP, rectWidth, RECT_HEIGHT);
	}

	// TODO: consider de-duplicating this code with the copied one from
	// chrome_slices/frontend.ts.
	let title = `[utid:${utid}]`;
	let subTitle = '';
	if (threadInfo) {
	if (threadInfo.pid !== undefined && threadInfo.pid !== 0) {
	let procName = threadInfo.procName ?? '';
	if (procName.startsWith('/')) {
	// Remove folder paths from name
	procName = procName.substring(procName.lastIndexOf('/') + 1);
	}
	title = `${procName} [${threadInfo.pid}]`;
	subTitle = `${threadInfo.threadName} [${threadInfo.tid}]`;
	} else {
	title = `${threadInfo.threadName} [${threadInfo.tid}]`;
	}
	}

	if (data.flags[i] & CPU_SLICE_FLAGS_REALTIME) {
	subTitle = subTitle + ' (RT)';
	}

	const right = Math.min(visWindowEndPx, rectEnd);
	const left = Math.max(rectStart, 0);
	const visibleWidth = Math.max(right - left, 1);
	title = cropText(title, charWidth, visibleWidth);
	subTitle = cropText(subTitle, charWidth, visibleWidth);
	const rectXCenter = left + visibleWidth / 2;
	ctx.fillStyle = textColor.cssString;
	ctx.font = '12px Roboto Condensed';
	ctx.fillText(title, rectXCenter, MARGIN_TOP + RECT_HEIGHT / 2 - 1);
	ctx.fillStyle = textColor.setAlpha(0.6).cssString;
	ctx.font = '10px Roboto Condensed';
	ctx.fillText(subTitle, rectXCenter, MARGIN_TOP + RECT_HEIGHT / 2 + 9);
	}

	const selection = this.trace.selection.selection;
	if (selection.kind === 'track_event') {
	if (selection.trackUri === this.uri) {
	const [startIndex, endIndex] = searchEq(data.ids, selection.eventId);
	if (startIndex !== endIndex) {
	const tStart = Time.fromRaw(data.startQs[startIndex]);
	const tEnd = Time.fromRaw(data.endQs[startIndex]);
	const utid = data.utids[startIndex];
	const color = colorForThread(this.threads.get(utid));
	const rectStart = timescale.timeToPx(tStart);
	const rectEnd = timescale.timeToPx(tEnd);
	const rectWidth = Math.max(1, rectEnd - rectStart);

	// Draw a rectangle around the slice that is currently selected.
	ctx.strokeStyle = color.base.setHSL({l: 30}).cssString;
	ctx.beginPath();
	ctx.lineWidth = 3;
	ctx.strokeRect(
	rectStart,
	MARGIN_TOP - 1.5,
	rectWidth,
	RECT_HEIGHT + 3,
	);
	ctx.closePath();
	// Draw arrow from wakeup time of current slice.
	if (selection.wakeupTs) {
	const wakeupPos = timescale.timeToPx(selection.wakeupTs);
	const latencyWidth = rectStart - wakeupPos;
	drawDoubleHeadedArrow(
	ctx,
	wakeupPos,
	MARGIN_TOP + RECT_HEIGHT,
	latencyWidth,
	latencyWidth >= 20,
	);
	// Latency time with a white semi-transparent background.
	const latency = tStart - selection.wakeupTs;
	const displayText = Duration.humanise(latency);
	const measured = ctx.measureText(displayText);
	if (latencyWidth >= measured.width + 2) {
	ctx.fillStyle = 'rgba(255,255,255,0.7)';
	ctx.fillRect(
	wakeupPos + latencyWidth / 2 - measured.width / 2 - 1,
	MARGIN_TOP + RECT_HEIGHT - 12,
	measured.width + 2,
	11,
	);
	ctx.textBaseline = 'bottom';
	ctx.fillStyle = 'black';
	ctx.fillText(
	displayText,
	wakeupPos + latencyWidth / 2,
	MARGIN_TOP + RECT_HEIGHT - 1,
	);
	}
	}
	}
	}

	// Draw diamond if the track being drawn is the cpu of the waker.
	if (this.cpu === selection.wakerCpu && selection.wakeupTs) {
	const wakeupPos = Math.floor(timescale.timeToPx(selection.wakeupTs));
	ctx.beginPath();
	ctx.moveTo(wakeupPos, MARGIN_TOP + RECT_HEIGHT / 2 + 8);
	ctx.fillStyle = 'black';
	ctx.lineTo(wakeupPos + 6, MARGIN_TOP + RECT_HEIGHT / 2);
	ctx.lineTo(wakeupPos, MARGIN_TOP + RECT_HEIGHT / 2 - 8);
	ctx.lineTo(wakeupPos - 6, MARGIN_TOP + RECT_HEIGHT / 2);
	ctx.fill();
	ctx.closePath();
	}

	if (this.utidHoveredInThisTrack !== undefined) {
	const hoveredThread = this.threads.get(this.utidHoveredInThisTrack);
	if (hoveredThread && this.mousePos !== undefined) {
	const tidText = `T: ${hoveredThread.threadName}
	[${hoveredThread.tid}]`;
	// eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
	if (hoveredThread.pid) {
	const pidText = `P: ${hoveredThread.procName}
	[${hoveredThread.pid}]`;
	drawTrackHoverTooltip(ctx, this.mousePos, size, pidText, tidText);
	} else {
	drawTrackHoverTooltip(ctx, this.mousePos, size, tidText);
	}
	}
	}
	}
	}

	onMouseMove({x, y, timescale}: TrackMouseEvent) {
	const data = this.fetcher.data;
	this.mousePos = {x, y};
	if (data === undefined) return;
	if (y < MARGIN_TOP \|\| y > MARGIN_TOP + RECT_HEIGHT) {
	this.utidHoveredInThisTrack = undefined;
	this.trace.timeline.hoveredUtid = undefined;
	this.trace.timeline.hoveredPid = undefined;
	return;
	}
	const t = timescale.pxToHpTime(x);
	let hoveredUtid = undefined;

	for (let i = 0; i < data.startQs.length; i++) {
	const tStart = Time.fromRaw(data.startQs[i]);
	const tEnd = Time.fromRaw(data.endQs[i]);
	const utid = data.utids[i];
	if (t.gte(tStart) && t.lt(tEnd)) {
	hoveredUtid = utid;
	break;
	}
	}
	this.utidHoveredInThisTrack = hoveredUtid;
	const threadInfo = exists(hoveredUtid) && this.threads.get(hoveredUtid);
	// eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
	const hoveredPid = threadInfo ? (threadInfo.pid ? threadInfo.pid : -1) : -1;
	this.trace.timeline.hoveredUtid = hoveredUtid;
	this.trace.timeline.hoveredPid = hoveredPid;
	}

	onMouseOut() {
	this.utidHoveredInThisTrack = -1;
	this.trace.timeline.hoveredUtid = undefined;
	this.trace.timeline.hoveredPid = undefined;
	this.mousePos = undefined;
	}

	onMouseClick({x, timescale}: TrackMouseEvent) {
	const data = this.fetcher.data;
	if (data === undefined) return false;
	const time = timescale.pxToHpTime(x);
	const index = search(data.startQs, time.toTime());
	const id = index === -1 ? undefined : data.ids[index];
	// eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
	if (!id \|\| this.utidHoveredInThisTrack === -1) return false;

	this.trace.selection.selectTrackEvent(this.uri, id);
	return true;
	}

	async getSelectionDetails?(
	eventId: number,
	): Promise<TrackEventDetails \| undefined> {
	const sched = await getSched(this.trace.engine, asSchedSqlId(eventId));
	if (sched === undefined) {
	return undefined;
	}
	const wakeup = await getSchedWakeupInfo(this.trace.engine, sched);
	return {
	ts: sched.ts,
	dur: sched.dur,
	wakeupTs: wakeup?.wakeupTs,
	wakerCpu: wakeup?.wakerCpu,
	};
	}

	detailsPanel() {
	return new SchedSliceDetailsPanel(this.trace, this.threads);
	}
	}

	// Creates a diagonal hatched pattern to be used for distinguishing slices with
	// real-time priorities. The pattern is created once as an offscreen canvas and
	// is kept cached inside the Context2D of the main canvas, without making
	// assumptions on the lifetime of the main canvas.
	function getHatchedPattern(mainCtx: CanvasRenderingContext2D): CanvasPattern {
	const mctx = mainCtx as CanvasRenderingContext2D & {
	sliceHatchedPattern?: CanvasPattern;
	};
	if (mctx.sliceHatchedPattern !== undefined) return mctx.sliceHatchedPattern;
	const canvas = document.createElement('canvas');
	const SIZE = 8;
	canvas.width = canvas.height = SIZE;
	const ctx = assertExists(canvas.getContext('2d'));
	ctx.strokeStyle = 'rgba(255,255,255,0.3)';
	ctx.beginPath();
	ctx.lineWidth = 1;
	ctx.moveTo(0, SIZE);
	ctx.lineTo(SIZE, 0);
	ctx.stroke();
	mctx.sliceHatchedPattern = assertExists(mctx.createPattern(canvas, 'repeat'));
	return mctx.sliceHatchedPattern;
	}