ui/src/controller/track_controller.ts - third_party/perfetto - Git at Google

 // Copyright (C) 2018 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 {assertExists, assertTrue} from '../base/logging';
 import {Engine} from '../common/engine';
 import {Registry} from '../common/registry';
 import {TraceTime, TrackState} from '../common/state';
 import {toNs} from '../common/time';
 import {LIMIT, TrackData} from '../common/track_data';

 import {Controller} from './controller';
 import {ControllerFactory} from './controller';
 import {globals} from './globals';

 interface TrackConfig {}

 type TrackConfigWithNamespace = TrackConfig&{namespace: string};

 // Allow to override via devtools for testing (note, needs to be done in the
 // controller-thread).
 (self as {} as {quantPx: number}).quantPx = 1;

 // TrackController is a base class overridden by track implementations (e.g.,
 // sched slices, nestable slices, counters).
 export abstract class TrackController<
     Config, Data extends TrackData = TrackData> extends Controller<'main'> {
   readonly trackId: string;
   readonly engine: Engine;
   private data?: TrackData;
   private requestingData = false;
   private queuedRequest = false;
   private isSetup = false;
   private lastReloadHandled = 0;

   // We choose 100000 as the table size to cache as this is roughly the point
   // where SQLite sorts start to become expensive.
   private static readonly MIN_TABLE_SIZE_TO_CACHE = 100000;

   constructor(args: TrackControllerArgs) {
     super('main');
     this.trackId = args.trackId;
     this.engine = args.engine;
   }

   protected pxSize(): number {
     return (self as {} as {quantPx: number}).quantPx;
   }

   // Can be overriden by the track implementation to allow one time setup work
   // to be performed before the first onBoundsChange invcation.
   async onSetup() {}

   // Can be overriden by the track implementation to allow some one-off work
   // when requested reload (e.g. recalculating height).
   async onReload() {}

   // Must be overridden by the track implementation. Is invoked when the track
   // frontend runs out of cached data. The derived track controller is expected
   // to publish new track data in response to this call.
   abstract async onBoundsChange(start: number, end: number, resolution: number):
       Promise<Data>;

   get trackState(): TrackState {
     return assertExists(globals.state.tracks[this.trackId]);
   }

   get config(): Config {
     return this.trackState.config as Config;
   }

   configHasNamespace(config: TrackConfig): config is TrackConfigWithNamespace {
     return 'namespace' in config;
   }

   namespaceTable(tableName: string): string {
     if (this.configHasNamespace(this.config)) {
       return this.config.namespace + '_' + tableName;
     } else {
       return tableName;
     }
   }

   publish(data: Data): void {
     this.data = data;
     globals.publish('TrackData', {id: this.trackId, data});
   }

   /**
    * Returns a valid SQL table name with the given prefix that should be unique
    * for each track.
    */
   tableName(prefix: string) {
     // Derive table name from, since that is unique for each track.
     // Track ID can be UUID but '-' is not valid for sql table name.
     const idSuffix = this.trackId.split('-').join('_');
     return `${prefix}_${idSuffix}`;
   }

   shouldSummarize(resolution: number): boolean {
     // |resolution| is in s/px (to nearest power of 10) assuming a display
     // of ~1000px 0.0008 is 0.8s.
     return resolution >= 0.0008;
   }

   protected async query(query: string) {
     const result = await this.engine.query(query);
     return result;
   }

   private shouldReload(): boolean {
     const {lastTrackReloadRequest} = globals.state;
     return !!lastTrackReloadRequest &&
         this.lastReloadHandled < lastTrackReloadRequest;
   }

   private markReloadHandled() {
     this.lastReloadHandled = globals.state.lastTrackReloadRequest || 0;
   }

   shouldRequestData(traceTime: TraceTime): boolean {
     if (this.data === undefined) return true;
     if (this.shouldReload()) return true;

     // If at the limit only request more data if the view has moved.
     const atLimit = this.data.length === LIMIT;
     if (atLimit) {
       // We request more data than the window, so add window duration to find
       // the previous window.
       const prevWindowStart =
           this.data.start + (traceTime.startSec - traceTime.endSec);
       return traceTime.startSec !== prevWindowStart;
     }

     // Otherwise request more data only when out of range of current data or
     // resolution has changed.
     const inRange = traceTime.startSec >= this.data.start &&
         traceTime.endSec <= this.data.end;
     return !inRange ||
         this.data.resolution !==
         globals.state.frontendLocalState.visibleState.resolution;
   }

   // Decides, based on the the length of the trace and the number of rows
   // provided whether a TrackController subclass should cache its quantized
   // data. Returns the bucket size (in ns) if caching should happen and
   // undefined otherwise.
   // Subclasses should call this in their setup function
   cachedBucketSizeNs(numRows: number): number|undefined {
     // Ensure that we're not caching when the table size isn't even that big.
     if (numRows < TrackController.MIN_TABLE_SIZE_TO_CACHE) {
       return undefined;
     }

     const bounds = globals.state.traceTime;
     const traceDurNs = toNs(bounds.endSec - bounds.startSec);

     // For large traces, going through the raw table in the most zoomed-out
     // states can be very expensive as this can involve going through O(millions
     // of rows). The cost of this becomes high even for just iteration but is
     // especially slow as quantization involves a SQLite sort on the quantized
     // timestamp (for the group by).
     //
     // To get around this, we can cache a pre-quantized table which we can then
     // in zoomed-out situations and fall back to the real table when zoomed in
     // (which naturally constrains the amount of data by virtue of the window
     // covering a smaller timespan)
     //
     // This method computes that cached table by computing an approximation for
     // the bucket size we would use when totally zoomed out and then going a few
     // resolution levels down which ensures that our cached table works for more
     // than the literally most zoomed out state. Moving down a resolution level
     // is defined as moving down a power of 2; this matches the logic in
     // |globals.getCurResolution|.
     //
     // TODO(lalitm): in the future, we should consider having a whole set of
     // quantized tables each of which cover some portion of resolution lvel
     // range. As each table covers a large number of resolution levels, even 3-4
     // tables should really cover the all concievable trace sizes. This set
     // could be computed by looking at the number of events being processed one
     // level below the cached table and computing another layer of caching if
     // that count is too high (with respect to MIN_TABLE_SIZE_TO_CACHE).

     // 4k monitors have 3840 horizontal pixels so use that for a worst case
     // approximation of the window width.
     const approxWidthPx = 3840;

     // Compute the outermost bucket size. This acts as a starting point for
     // computing the cached size.
     const outermostResolutionLevel =
         Math.ceil(Math.log2(traceDurNs / approxWidthPx));
     const outermostBucketNs = Math.pow(2, outermostResolutionLevel);

     // This constant decides how many resolution levels down from our outermost
     // bucket computation we want to be able to use the cached table.
     // We've chosen 7 as it seems to be empircally seems to be a good fit for
     // trace data.
     const resolutionLevelsCovered = 7;

     // If we've got less resolution levels in the trace than the number of
     // resolution levels we want to go down, bail out because this cached
     // table is really not going to be used enough.
     if (outermostResolutionLevel < resolutionLevelsCovered) {
       return Number.MAX_SAFE_INTEGER;
     }

     // Another way to look at moving down resolution levels is to consider how
     // many sub-intervals we are splitting the bucket into.
     const bucketSubIntervals = Math.pow(2, resolutionLevelsCovered);

     // Calculate the smallest bucket we want our table to be able to handle by
     // dividing the outermsot bucket by the number of subintervals we should
     // divide by.
     const cachedBucketSizeNs = outermostBucketNs / bucketSubIntervals;

     // Our logic above should make sure this is an integer but double check that
     // here as an assertion before returning.
     assertTrue(Number.isInteger(cachedBucketSizeNs));

     return cachedBucketSizeNs;
   }

   run() {
     const visibleState = globals.state.frontendLocalState.visibleState;
     if (visibleState === undefined || visibleState.resolution === undefined ||
         visibleState.resolution === Infinity) {
       return;
     }
     const dur = visibleState.endSec - visibleState.startSec;
     if (globals.state.visibleTracks.includes(this.trackId) &&
         this.shouldRequestData(visibleState)) {
       if (this.requestingData) {
         this.queuedRequest = true;
       } else {
         this.requestingData = true;
         let promise = Promise.resolve();
         if (!this.isSetup) {
           promise = this.onSetup();
         } else if (this.shouldReload()) {
           promise = this.onReload().then(() => this.markReloadHandled());
         }
         promise
             .then(() => {
               this.isSetup = true;
               return this.onBoundsChange(
                   visibleState.startSec - dur,
                   visibleState.endSec + dur,
                   visibleState.resolution);
             })
             .then(data => {
               this.publish(data);
             })
             .finally(() => {
               this.requestingData = false;
               if (this.queuedRequest) {
                 this.queuedRequest = false;
                 this.run();
               }
             });
       }
     }
   }
 }

 export interface TrackControllerArgs {
   trackId: string;
   engine: Engine;
 }

 export interface TrackControllerFactory extends
     ControllerFactory<TrackControllerArgs> {
   kind: string;
 }

 export const trackControllerRegistry = new Registry<TrackControllerFactory>();
	// Copyright (C) 2018 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 {assertExists, assertTrue} from '../base/logging';
	import {Engine} from '../common/engine';
	import {Registry} from '../common/registry';
	import {TraceTime, TrackState} from '../common/state';
	import {toNs} from '../common/time';
	import {LIMIT, TrackData} from '../common/track_data';

	import {Controller} from './controller';
	import {ControllerFactory} from './controller';
	import {globals} from './globals';

	interface TrackConfig {}

	type TrackConfigWithNamespace = TrackConfig&{namespace: string};

	// Allow to override via devtools for testing (note, needs to be done in the
	// controller-thread).
	(self as {} as {quantPx: number}).quantPx = 1;

	// TrackController is a base class overridden by track implementations (e.g.,
	// sched slices, nestable slices, counters).
	export abstract class TrackController<
	Config, Data extends TrackData = TrackData> extends Controller<'main'> {
	readonly trackId: string;
	readonly engine: Engine;
	private data?: TrackData;
	private requestingData = false;
	private queuedRequest = false;
	private isSetup = false;
	private lastReloadHandled = 0;

	// We choose 100000 as the table size to cache as this is roughly the point
	// where SQLite sorts start to become expensive.
	private static readonly MIN_TABLE_SIZE_TO_CACHE = 100000;

	constructor(args: TrackControllerArgs) {
	super('main');
	this.trackId = args.trackId;
	this.engine = args.engine;
	}

	protected pxSize(): number {
	return (self as {} as {quantPx: number}).quantPx;
	}

	// Can be overriden by the track implementation to allow one time setup work
	// to be performed before the first onBoundsChange invcation.
	async onSetup() {}

	// Can be overriden by the track implementation to allow some one-off work
	// when requested reload (e.g. recalculating height).
	async onReload() {}

	// Must be overridden by the track implementation. Is invoked when the track
	// frontend runs out of cached data. The derived track controller is expected
	// to publish new track data in response to this call.
	abstract async onBoundsChange(start: number, end: number, resolution: number):
	Promise<Data>;

	get trackState(): TrackState {
	return assertExists(globals.state.tracks[this.trackId]);
	}

	get config(): Config {
	return this.trackState.config as Config;
	}

	configHasNamespace(config: TrackConfig): config is TrackConfigWithNamespace {
	return 'namespace' in config;
	}

	namespaceTable(tableName: string): string {
	if (this.configHasNamespace(this.config)) {
	return this.config.namespace + '_' + tableName;
	} else {
	return tableName;
	}
	}

	publish(data: Data): void {
	this.data = data;
	globals.publish('TrackData', {id: this.trackId, data});
	}

	/**
	* Returns a valid SQL table name with the given prefix that should be unique
	* for each track.
	*/
	tableName(prefix: string) {
	// Derive table name from, since that is unique for each track.
	// Track ID can be UUID but '-' is not valid for sql table name.
	const idSuffix = this.trackId.split('-').join('_');
	return `${prefix}_${idSuffix}`;
	}

	shouldSummarize(resolution: number): boolean {
	// \|resolution\| is in s/px (to nearest power of 10) assuming a display
	// of ~1000px 0.0008 is 0.8s.
	return resolution >= 0.0008;
	}

	protected async query(query: string) {
	const result = await this.engine.query(query);
	return result;
	}

	private shouldReload(): boolean {
	const {lastTrackReloadRequest} = globals.state;
	return !!lastTrackReloadRequest &&
	this.lastReloadHandled < lastTrackReloadRequest;
	}

	private markReloadHandled() {
	this.lastReloadHandled = globals.state.lastTrackReloadRequest \|\| 0;
	}

	shouldRequestData(traceTime: TraceTime): boolean {
	if (this.data === undefined) return true;
	if (this.shouldReload()) return true;

	// If at the limit only request more data if the view has moved.
	const atLimit = this.data.length === LIMIT;
	if (atLimit) {
	// We request more data than the window, so add window duration to find
	// the previous window.
	const prevWindowStart =
	this.data.start + (traceTime.startSec - traceTime.endSec);
	return traceTime.startSec !== prevWindowStart;
	}

	// Otherwise request more data only when out of range of current data or
	// resolution has changed.
	const inRange = traceTime.startSec >= this.data.start &&
	traceTime.endSec <= this.data.end;
	return !inRange \|\|
	this.data.resolution !==
	globals.state.frontendLocalState.visibleState.resolution;
	}

	// Decides, based on the the length of the trace and the number of rows
	// provided whether a TrackController subclass should cache its quantized
	// data. Returns the bucket size (in ns) if caching should happen and
	// undefined otherwise.
	// Subclasses should call this in their setup function
	cachedBucketSizeNs(numRows: number): number\|undefined {
	// Ensure that we're not caching when the table size isn't even that big.
	if (numRows < TrackController.MIN_TABLE_SIZE_TO_CACHE) {
	return undefined;
	}

	const bounds = globals.state.traceTime;
	const traceDurNs = toNs(bounds.endSec - bounds.startSec);

	// For large traces, going through the raw table in the most zoomed-out
	// states can be very expensive as this can involve going through O(millions
	// of rows). The cost of this becomes high even for just iteration but is
	// especially slow as quantization involves a SQLite sort on the quantized
	// timestamp (for the group by).
	//
	// To get around this, we can cache a pre-quantized table which we can then
	// in zoomed-out situations and fall back to the real table when zoomed in
	// (which naturally constrains the amount of data by virtue of the window
	// covering a smaller timespan)
	//
	// This method computes that cached table by computing an approximation for
	// the bucket size we would use when totally zoomed out and then going a few
	// resolution levels down which ensures that our cached table works for more
	// than the literally most zoomed out state. Moving down a resolution level
	// is defined as moving down a power of 2; this matches the logic in
	// \|globals.getCurResolution\|.
	//
	// TODO(lalitm): in the future, we should consider having a whole set of
	// quantized tables each of which cover some portion of resolution lvel
	// range. As each table covers a large number of resolution levels, even 3-4
	// tables should really cover the all concievable trace sizes. This set
	// could be computed by looking at the number of events being processed one
	// level below the cached table and computing another layer of caching if
	// that count is too high (with respect to MIN_TABLE_SIZE_TO_CACHE).

	// 4k monitors have 3840 horizontal pixels so use that for a worst case
	// approximation of the window width.
	const approxWidthPx = 3840;

	// Compute the outermost bucket size. This acts as a starting point for
	// computing the cached size.
	const outermostResolutionLevel =
	Math.ceil(Math.log2(traceDurNs / approxWidthPx));
	const outermostBucketNs = Math.pow(2, outermostResolutionLevel);

	// This constant decides how many resolution levels down from our outermost
	// bucket computation we want to be able to use the cached table.
	// We've chosen 7 as it seems to be empircally seems to be a good fit for
	// trace data.
	const resolutionLevelsCovered = 7;

	// If we've got less resolution levels in the trace than the number of
	// resolution levels we want to go down, bail out because this cached
	// table is really not going to be used enough.
	if (outermostResolutionLevel < resolutionLevelsCovered) {
	return Number.MAX_SAFE_INTEGER;
	}

	// Another way to look at moving down resolution levels is to consider how
	// many sub-intervals we are splitting the bucket into.
	const bucketSubIntervals = Math.pow(2, resolutionLevelsCovered);

	// Calculate the smallest bucket we want our table to be able to handle by
	// dividing the outermsot bucket by the number of subintervals we should
	// divide by.
	const cachedBucketSizeNs = outermostBucketNs / bucketSubIntervals;

	// Our logic above should make sure this is an integer but double check that
	// here as an assertion before returning.
	assertTrue(Number.isInteger(cachedBucketSizeNs));

	return cachedBucketSizeNs;
	}

	run() {
	const visibleState = globals.state.frontendLocalState.visibleState;
	if (visibleState === undefined \|\| visibleState.resolution === undefined \|\|
	visibleState.resolution === Infinity) {
	return;
	}
	const dur = visibleState.endSec - visibleState.startSec;
	if (globals.state.visibleTracks.includes(this.trackId) &&
	this.shouldRequestData(visibleState)) {
	if (this.requestingData) {
	this.queuedRequest = true;
	} else {
	this.requestingData = true;
	let promise = Promise.resolve();
	if (!this.isSetup) {
	promise = this.onSetup();
	} else if (this.shouldReload()) {
	promise = this.onReload().then(() => this.markReloadHandled());
	}
	promise
	.then(() => {
	this.isSetup = true;
	return this.onBoundsChange(
	visibleState.startSec - dur,
	visibleState.endSec + dur,
	visibleState.resolution);
	})
	.then(data => {
	this.publish(data);
	})
	.finally(() => {
	this.requestingData = false;
	if (this.queuedRequest) {
	this.queuedRequest = false;
	this.run();
	}
	});
	}
	}
	}
	}

	export interface TrackControllerArgs {
	trackId: string;
	engine: Engine;
	}

	export interface TrackControllerFactory extends
	ControllerFactory<TrackControllerArgs> {
	kind: string;
	}

	export const trackControllerRegistry = new Registry<TrackControllerFactory>();