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// 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 {
Actions,
DeferredAction,
} from '../common/actions';
import {cacheTrace} from '../common/cache_manager';
import {TRACE_MARGIN_TIME_S} from '../common/constants';
import {Engine} from '../common/engine';
import {featureFlags, Flag, PERF_SAMPLE_FLAG} from '../common/feature_flags';
import {HttpRpcEngine} from '../common/http_rpc_engine';
import {NUM, NUM_NULL, QueryError, STR, STR_NULL} from '../common/query_result';
import {defaultTraceTime, EngineMode} from '../common/state';
import {TimeSpan, toNs, toNsCeil, toNsFloor} from '../common/time';
import {resetEngineWorker, WasmEngineProxy} from '../common/wasm_engine_proxy';
import {
globals as frontendGlobals,
QuantizedLoad,
ThreadDesc,
} from '../frontend/globals';
import {
publishHasFtrace,
publishMetricError,
publishOverviewData,
publishThreads,
} from '../frontend/publish';
import {Router} from '../frontend/router';
import {
CounterAggregationController,
} from './aggregation/counter_aggregation_controller';
import {
CpuAggregationController,
} from './aggregation/cpu_aggregation_controller';
import {
CpuByProcessAggregationController,
} from './aggregation/cpu_by_process_aggregation_controller';
import {
FrameAggregationController,
} from './aggregation/frame_aggregation_controller';
import {
SliceAggregationController,
} from './aggregation/slice_aggregation_controller';
import {
ThreadAggregationController,
} from './aggregation/thread_aggregation_controller';
import {Child, Children, Controller} from './controller';
import {
CpuProfileController,
CpuProfileControllerArgs,
} from './cpu_profile_controller';
import {
FlamegraphController,
FlamegraphControllerArgs,
} from './flamegraph_controller';
import {
FlowEventsController,
FlowEventsControllerArgs,
} from './flow_events_controller';
import {globals} from './globals';
import {LoadingManager} from './loading_manager';
import {LogsController} from './logs_controller';
import {MetricsController} from './metrics_controller';
import {PivotTableReduxController} from './pivot_table_redux_controller';
import {QueryController, QueryControllerArgs} from './query_controller';
import {SearchController} from './search_controller';
import {
SelectionController,
SelectionControllerArgs,
} from './selection_controller';
import {
TraceErrorController,
} from './trace_error_controller';
import {
TraceBufferStream,
TraceFileStream,
TraceHttpStream,
TraceStream,
} from './trace_stream';
import {TrackControllerArgs, trackControllerRegistry} from './track_controller';
import {decideTracks} from './track_decider';
import {VisualisedArgController} from './visualised_args_controller';
type States = 'init' | 'loading_trace' | 'ready';
const METRICS = [
'android_startup',
'android_ion',
'android_lmk',
'android_dma_heap',
'android_surfaceflinger',
'android_batt',
'android_sysui_cuj',
'android_camera',
'android_other_traces',
'chrome_dropped_frames',
'chrome_long_latency',
'trace_metadata',
'android_trusty_workqueues',
];
const FLAGGED_METRICS: Array<[Flag, string]> = METRICS.map((m) => {
const id = `forceMetric${m}`;
let name = m.split('_').join(' ') + ' metric';
name = name[0].toUpperCase() + name.slice(1);
const flag = featureFlags.register({
id,
name,
description: `Overrides running the '${m}' metric at import time.`,
defaultValue: true,
});
return [flag, m];
});
// TraceController handles handshakes with the frontend for everything that
// concerns a single trace. It owns the WASM trace processor engine, handles
// tracks data and SQL queries. There is one TraceController instance for each
// trace opened in the UI (for now only one trace is supported).
export class TraceController extends Controller<States> {
private readonly engineId: string;
private engine?: Engine;
constructor(engineId: string) {
super('init');
this.engineId = engineId;
}
run() {
const engineCfg = assertExists(globals.state.engines[this.engineId]);
switch (this.state) {
case 'init':
this.loadTrace()
.then((mode) => {
globals.dispatch(Actions.setEngineReady({
engineId: this.engineId,
ready: true,
mode,
}));
})
.catch((err) => {
this.updateStatus(`${err}`);
throw err;
});
this.updateStatus('Opening trace');
this.setState('loading_trace');
break;
case 'loading_trace':
// Stay in this state until loadTrace() returns and marks the engine as
// ready.
if (this.engine === undefined || !engineCfg.ready) return;
this.setState('ready');
break;
case 'ready':
// At this point we are ready to serve queries and handle tracks.
const engine = assertExists(this.engine);
const childControllers: Children = [];
// Create a TrackController for each track.
for (const trackId of Object.keys(globals.state.tracks)) {
const trackCfg = globals.state.tracks[trackId];
if (trackCfg.engineId !== this.engineId) continue;
if (!trackControllerRegistry.has(trackCfg.kind)) continue;
const trackCtlFactory = trackControllerRegistry.get(trackCfg.kind);
const trackArgs: TrackControllerArgs = {trackId, engine};
childControllers.push(Child(trackId, trackCtlFactory, trackArgs));
}
// Create a QueryController for each query.
for (const queryId of Object.keys(globals.state.queries)) {
// If the expected engineId was not specified in the query, we
// assume it's `state.currentEngineId`. The engineId is not specified
// for instances with queries created prior to the creation of the
// first engine.
const expectedEngineId = globals.state.queries[queryId].engineId ||
frontendGlobals.state.currentEngineId;
// Check that we are executing the query on the correct engine.
if (expectedEngineId !== engine.id) {
continue;
}
const queryArgs: QueryControllerArgs = {queryId, engine};
childControllers.push(Child(queryId, QueryController, queryArgs));
}
for (const argName of globals.state.visualisedArgs) {
childControllers.push(
Child(argName, VisualisedArgController, {argName, engine}));
}
const selectionArgs: SelectionControllerArgs = {engine};
childControllers.push(
Child('selection', SelectionController, selectionArgs));
const flowEventsArgs: FlowEventsControllerArgs = {engine};
childControllers.push(
Child('flowEvents', FlowEventsController, flowEventsArgs));
const cpuProfileArgs: CpuProfileControllerArgs = {engine};
childControllers.push(
Child('cpuProfile', CpuProfileController, cpuProfileArgs));
const flamegraphArgs: FlamegraphControllerArgs = {engine};
childControllers.push(
Child('flamegraph', FlamegraphController, flamegraphArgs));
childControllers.push(Child(
'cpu_aggregation',
CpuAggregationController,
{engine, kind: 'cpu_aggregation'}));
childControllers.push(Child(
'thread_aggregation',
ThreadAggregationController,
{engine, kind: 'thread_state_aggregation'}));
childControllers.push(Child(
'cpu_process_aggregation',
CpuByProcessAggregationController,
{engine, kind: 'cpu_by_process_aggregation'}));
childControllers.push(Child(
'slice_aggregation',
SliceAggregationController,
{engine, kind: 'slice_aggregation'}));
childControllers.push(Child(
'counter_aggregation',
CounterAggregationController,
{engine, kind: 'counter_aggregation'}));
childControllers.push(Child(
'frame_aggregation',
FrameAggregationController,
{engine, kind: 'frame_aggregation'}));
childControllers.push(Child('search', SearchController, {
engine,
app: globals,
}));
childControllers.push(
Child('pivot_table_redux', PivotTableReduxController, {engine}));
childControllers.push(Child('logs', LogsController, {
engine,
app: globals,
}));
childControllers.push(
Child('traceError', TraceErrorController, {engine}));
childControllers.push(Child('metrics', MetricsController, {engine}));
return childControllers;
default:
throw new Error(`unknown state ${this.state}`);
}
return;
}
onDestroy() {
frontendGlobals.engines.delete(this.engineId);
}
private async loadTrace(): Promise<EngineMode> {
this.updateStatus('Creating trace processor');
// Check if there is any instance of the trace_processor_shell running in
// HTTP RPC mode (i.e. trace_processor_shell -D).
let engineMode: EngineMode;
let useRpc = false;
if (globals.state.newEngineMode === 'USE_HTTP_RPC_IF_AVAILABLE') {
useRpc = (await HttpRpcEngine.checkConnection()).connected;
}
let engine;
if (useRpc) {
console.log('Opening trace using native accelerator over HTTP+RPC');
engineMode = 'HTTP_RPC';
engine = new HttpRpcEngine(this.engineId, LoadingManager.getInstance);
engine.errorHandler = (err) => {
globals.dispatch(
Actions.setEngineFailed({mode: 'HTTP_RPC', failure: `${err}`}));
throw err;
};
} else {
console.log('Opening trace using built-in WASM engine');
engineMode = 'WASM';
const enginePort = resetEngineWorker();
engine = new WasmEngineProxy(
this.engineId, enginePort, LoadingManager.getInstance);
}
this.engine = engine;
frontendGlobals.engines.set(this.engineId, engine);
globals.dispatch(Actions.setEngineReady({
engineId: this.engineId,
ready: false,
mode: engineMode,
}));
const engineCfg = assertExists(globals.state.engines[this.engineId]);
let traceStream: TraceStream | undefined;
if (engineCfg.source.type === 'FILE') {
traceStream = new TraceFileStream(engineCfg.source.file);
} else if (engineCfg.source.type === 'ARRAY_BUFFER') {
traceStream = new TraceBufferStream(engineCfg.source.buffer);
} else if (engineCfg.source.type === 'URL') {
traceStream = new TraceHttpStream(engineCfg.source.url);
} else if (engineCfg.source.type === 'HTTP_RPC') {
traceStream = undefined;
} else {
throw new Error(`Unknown source: ${JSON.stringify(engineCfg.source)}`);
}
// |traceStream| can be undefined in the case when we are using the external
// HTTP+RPC endpoint and the trace processor instance has already loaded
// a trace (because it was passed as a cmdline argument to
// trace_processor_shell). In this case we don't want the UI to load any
// file/stream and we just want to jump to the loading phase.
if (traceStream !== undefined) {
const tStart = performance.now();
for (; ;) {
const res = await traceStream.readChunk();
await this.engine.parse(res.data);
const elapsed = (performance.now() - tStart) / 1000;
let status = 'Loading trace ';
if (res.bytesTotal > 0) {
const progress = Math.round(res.bytesRead / res.bytesTotal * 100);
status += `${progress}%`;
} else {
status += `${Math.round(res.bytesRead / 1e6)} MB`;
}
status += ` - ${Math.ceil(res.bytesRead / elapsed / 1e6)} MB/s`;
this.updateStatus(status);
if (res.eof) break;
}
await this.engine.notifyEof();
} else {
assertTrue(this.engine instanceof HttpRpcEngine);
await this.engine.restoreInitialTables();
}
// traceUuid will be '' if the trace is not cacheable (URL or RPC).
const traceUuid = await this.cacheCurrentTrace();
const traceTime = await this.engine.getTraceTimeBounds();
let startSec = traceTime.start;
let endSec = traceTime.end;
startSec -= TRACE_MARGIN_TIME_S;
endSec += TRACE_MARGIN_TIME_S;
const traceTimeState = {
startSec,
endSec,
};
const emptyOmniboxState = {
omnibox: '',
mode: frontendGlobals.state.frontendLocalState.omniboxState.mode ||
'SEARCH',
lastUpdate: Date.now() / 1000,
};
const actions: DeferredAction[] = [
Actions.setOmnibox(emptyOmniboxState),
Actions.setTraceUuid({traceUuid}),
Actions.setTraceTime(traceTimeState),
];
const [startVisibleTime, endVisibleTime] =
await computeVisibleTime(startSec, endSec, this.engine);
// We don't know the resolution at this point. However this will be
// replaced in 50ms so a guess is fine.
const resolution = (endVisibleTime - startVisibleTime) / 1000;
actions.push(Actions.setVisibleTraceTime({
startSec: startVisibleTime,
endSec: endVisibleTime,
lastUpdate: Date.now() / 1000,
resolution,
}));
globals.dispatchMultiple(actions);
Router.navigate(`#!/viewer?local_cache_key=${traceUuid}`);
// Make sure the helper views are available before we start adding tracks.
await this.initialiseHelperViews();
{
// When we reload from a permalink don't create extra tracks:
const {pinnedTracks, tracks} = globals.state;
if (!pinnedTracks.length && !Object.keys(tracks).length) {
await this.listTracks();
}
}
await this.listThreads();
await this.loadTimelineOverview(traceTime);
{
// A quick heuristic to check if the trace has ftrace events. This is
// based on the assumption that most traces that have ftrace either:
// - Are proto traces captured via perfetto, in which case traced_probes
// emits ftrace per-cpu stats that end up in the stats table.
// - Have a raw event with non-zero cpu or utid.
// Notes:
// - The "+1 > 1" is to avoid pushing down the constraints to the "raw"
// table, which would compute a full column filter without being aware
// of the limit 1, and instead delegate the filtering to the iterator.
const query = `select '_' as _ from raw
where cpu + 1 > 1 or utid + 1 > 1 limit 1`;
const result = await assertExists(this.engine).query(query);
const hasFtrace = result.numRows() > 0;
publishHasFtrace(hasFtrace);
}
globals.dispatch(Actions.removeDebugTrack({}));
globals.dispatch(Actions.sortThreadTracks({}));
globals.dispatch(Actions.maybeExpandOnlyTrackGroup({}));
await this.selectFirstHeapProfile();
if (PERF_SAMPLE_FLAG.get()) {
await this.selectPerfSample();
}
return engineMode;
}
private async selectPerfSample() {
const query = `select ts, upid
from perf_sample
join thread using (utid)
order by ts desc limit 1`;
const profile = await assertExists(this.engine).query(query);
if (profile.numRows() !== 1) return;
const row = profile.firstRow({ts: NUM, upid: NUM});
const ts = row.ts;
const upid = row.upid;
globals.dispatch(
Actions.selectPerfSamples({id: 0, upid, ts, type: 'perf'}));
}
private async selectFirstHeapProfile() {
const query = `select * from
(select distinct(ts) as ts, 'native' as type,
upid from heap_profile_allocation
union
select distinct(graph_sample_ts) as ts, 'graph' as type, upid from
heap_graph_object) order by ts limit 1`;
const profile = await assertExists(this.engine).query(query);
if (profile.numRows() !== 1) return;
const row = profile.firstRow({ts: NUM, type: STR, upid: NUM});
const ts = row.ts;
const type = row.type;
const upid = row.upid;
globals.dispatch(Actions.selectHeapProfile({id: 0, upid, ts, type}));
}
private async listTracks() {
this.updateStatus('Loading tracks');
const engine = assertExists<Engine>(this.engine);
const actions = await decideTracks(this.engineId, engine);
globals.dispatchMultiple(actions);
}
private async listThreads() {
this.updateStatus('Reading thread list');
const query = `select
utid,
tid,
pid,
ifnull(thread.name, '') as threadName,
ifnull(
case when length(process.name) > 0 then process.name else null end,
thread.name) as procName,
process.cmdline as cmdline
from (select * from thread order by upid) as thread
left join (select * from process order by upid) as process
using(upid)`;
const result = await assertExists(this.engine).query(query);
const threads: ThreadDesc[] = [];
const it = result.iter({
utid: NUM,
tid: NUM,
pid: NUM_NULL,
threadName: STR,
procName: STR_NULL,
cmdline: STR_NULL,
});
for (; it.valid(); it.next()) {
const utid = it.utid;
const tid = it.tid;
const pid = it.pid === null ? undefined : it.pid;
const threadName = it.threadName;
const procName = it.procName === null ? undefined : it.procName;
const cmdline = it.cmdline === null ? undefined : it.cmdline;
threads.push({utid, tid, threadName, pid, procName, cmdline});
}
publishThreads(threads);
}
private async loadTimelineOverview(traceTime: TimeSpan) {
const engine = assertExists<Engine>(this.engine);
const numSteps = 100;
const stepSec = traceTime.duration / numSteps;
let hasSchedOverview = false;
for (let step = 0; step < numSteps; step++) {
this.updateStatus(
'Loading overview ' +
`${Math.round((step + 1) / numSteps * 1000) / 10}%`);
const startSec = traceTime.start + step * stepSec;
const startNs = toNsFloor(startSec);
const endSec = startSec + stepSec;
const endNs = toNsCeil(endSec);
// Sched overview.
const schedResult = await engine.query(
`select sum(dur)/${stepSec}/1e9 as load, cpu from sched ` +
`where ts >= ${startNs} and ts < ${endNs} and utid != 0 ` +
'group by cpu order by cpu');
const schedData: { [key: string]: QuantizedLoad } = {};
const it = schedResult.iter({load: NUM, cpu: NUM});
for (; it.valid(); it.next()) {
const load = it.load;
const cpu = it.cpu;
schedData[cpu] = {startSec, endSec, load};
hasSchedOverview = true;
}
publishOverviewData(schedData);
}
if (hasSchedOverview) {
return;
}
// Slices overview.
const traceStartNs = toNs(traceTime.start);
const stepSecNs = toNs(stepSec);
const sliceResult = await engine.query(`select
bucket,
upid,
ifnull(sum(utid_sum) / cast(${stepSecNs} as float), 0) as load
from thread
inner join (
select
ifnull(cast((ts - ${traceStartNs})/${stepSecNs} as int), 0) as bucket,
sum(dur) as utid_sum,
utid
from slice
inner join thread_track on slice.track_id = thread_track.id
group by bucket, utid
) using(utid)
where upid is not null
group by bucket, upid`);
const slicesData: { [key: string]: QuantizedLoad[] } = {};
const it = sliceResult.iter({bucket: NUM, upid: NUM, load: NUM});
for (; it.valid(); it.next()) {
const bucket = it.bucket;
const upid = it.upid;
const load = it.load;
const startSec = traceTime.start + stepSec * bucket;
const endSec = startSec + stepSec;
const upidStr = upid.toString();
let loadArray = slicesData[upidStr];
if (loadArray === undefined) {
loadArray = slicesData[upidStr] = [];
}
loadArray.push({startSec, endSec, load});
}
publishOverviewData(slicesData);
}
private async cacheCurrentTrace(): Promise<string> {
const engine = assertExists(this.engine);
const result = await engine.query(`select str_value as uuid from metadata
where name = 'trace_uuid'`);
if (result.numRows() === 0) {
// One of the cases covered is an empty trace.
return '';
}
const traceUuid = result.firstRow({uuid: STR}).uuid;
const engineConfig = assertExists(globals.state.engines[engine.id]);
if (!(await cacheTrace(engineConfig.source, traceUuid))) {
// If the trace is not cacheable (cacheable means it has been opened from
// URL or RPC) only append '?local_cache_key' to the URL, without the
// local_cache_key value. Doing otherwise would cause an error if the tab
// is discarded or the user hits the reload button because the trace is
// not in the cache.
return '';
}
return traceUuid;
}
async initialiseHelperViews() {
const engine = assertExists<Engine>(this.engine);
this.updateStatus('Creating annotation counter track table');
// Create the helper tables for all the annotations related data.
// NULL in min/max means "figure it out per track in the usual way".
await engine.query(`
CREATE TABLE annotation_counter_track(
id INTEGER PRIMARY KEY,
name STRING,
__metric_name STRING,
upid INTEGER,
min_value DOUBLE,
max_value DOUBLE
);
`);
this.updateStatus('Creating annotation slice track table');
await engine.query(`
CREATE TABLE annotation_slice_track(
id INTEGER PRIMARY KEY,
name STRING,
__metric_name STRING,
upid INTEGER,
group_name STRING
);
`);
this.updateStatus('Creating annotation counter table');
await engine.query(`
CREATE TABLE annotation_counter(
id BIG INT,
track_id INT,
ts BIG INT,
value DOUBLE,
PRIMARY KEY (track_id, ts)
) WITHOUT ROWID;
`);
this.updateStatus('Creating annotation slice table');
await engine.query(`
CREATE TABLE annotation_slice(
id INTEGER PRIMARY KEY,
track_id INT,
ts BIG INT,
dur BIG INT,
depth INT,
cat STRING,
name STRING,
UNIQUE(track_id, ts)
);
`);
const availableMetrics = [];
const metricsResult = await engine.query('select name from trace_metrics');
for (const it = metricsResult.iter({name: STR}); it.valid(); it.next()) {
availableMetrics.push(it.name);
}
globals.dispatch(Actions.setAvailableMetrics({availableMetrics}));
const availableMetricsSet = new Set<string>(availableMetrics);
for (const [flag, metric] of FLAGGED_METRICS) {
if (!flag.get() || !availableMetricsSet.has(metric)) {
continue;
}
this.updateStatus(`Computing ${metric} metric`);
try {
// We don't care about the actual result of metric here as we are just
// interested in the annotation tracks.
await engine.computeMetric([metric]);
} catch (e) {
if (e instanceof QueryError) {
publishMetricError('MetricError: ' + e.message);
continue;
} else {
throw e;
}
}
this.updateStatus(`Inserting data for ${metric} metric`);
try {
const result = await engine.query(`pragma table_info(${metric}_event)`);
let hasSliceName = false;
let hasDur = false;
let hasUpid = false;
let hasValue = false;
let hasGroupName = false;
const it = result.iter({name: STR});
for (; it.valid(); it.next()) {
const name = it.name;
hasSliceName = hasSliceName || name === 'slice_name';
hasDur = hasDur || name === 'dur';
hasUpid = hasUpid || name === 'upid';
hasValue = hasValue || name === 'value';
hasGroupName = hasGroupName || name === 'group_name';
}
const upidColumnSelect = hasUpid ? 'upid' : '0 AS upid';
const upidColumnWhere = hasUpid ? 'upid' : '0';
const groupNameColumn =
hasGroupName ? 'group_name' : 'NULL AS group_name';
if (hasSliceName && hasDur) {
await engine.query(`
INSERT INTO annotation_slice_track(
name, __metric_name, upid, group_name)
SELECT DISTINCT
track_name,
'${metric}' as metric_name,
${upidColumnSelect},
${groupNameColumn}
FROM ${metric}_event
WHERE track_type = 'slice'
`);
await engine.query(`
INSERT INTO annotation_slice(track_id, ts, dur, depth, cat, name)
SELECT
t.id AS track_id,
ts,
dur,
0 AS depth,
a.track_name as cat,
slice_name AS name
FROM ${metric}_event a
JOIN annotation_slice_track t
ON a.track_name = t.name AND t.__metric_name = '${metric}'
ORDER BY t.id, ts
`);
}
if (hasValue) {
const minMax = await engine.query(`
SELECT
IFNULL(MIN(value), 0) as minValue,
IFNULL(MAX(value), 0) as maxValue
FROM ${metric}_event
WHERE ${upidColumnWhere} != 0`);
const row = minMax.firstRow({minValue: NUM, maxValue: NUM});
await engine.query(`
INSERT INTO annotation_counter_track(
name, __metric_name, min_value, max_value, upid)
SELECT DISTINCT
track_name,
'${metric}' as metric_name,
CASE ${upidColumnWhere} WHEN 0 THEN NULL ELSE ${row.minValue} END,
CASE ${upidColumnWhere} WHEN 0 THEN NULL ELSE ${row.maxValue} END,
${upidColumnSelect}
FROM ${metric}_event
WHERE track_type = 'counter'
`);
await engine.query(`
INSERT INTO annotation_counter(id, track_id, ts, value)
SELECT
-1 as id,
t.id AS track_id,
ts,
value
FROM ${metric}_event a
JOIN annotation_counter_track t
ON a.track_name = t.name AND t.__metric_name = '${metric}'
ORDER BY t.id, ts
`);
}
} catch (e) {
if (e instanceof QueryError) {
publishMetricError('MetricError: ' + e.message);
} else {
throw e;
}
}
}
}
private updateStatus(msg: string): void {
globals.dispatch(Actions.updateStatus({
msg,
timestamp: Date.now() / 1000,
}));
}
}
async function computeVisibleTime(
traceStartSec: number, traceEndSec: number, engine: Engine):
Promise<[number, number]> {
// if we have non-default visible state, update the visible time to it
const previousVisibleState = globals.state.frontendLocalState.visibleState;
if (!(previousVisibleState.startSec === defaultTraceTime.startSec &&
previousVisibleState.endSec === defaultTraceTime.endSec)) {
return [previousVisibleState.startSec, previousVisibleState.endSec];
}
// initialise visible time to the trace time bounds
let visibleStartSec = traceStartSec;
let visibleEndSec = traceEndSec;
// compare start and end with metadata computed by the trace processor
const mdTime = await engine.getTracingMetadataTimeBounds();
// make sure the bounds hold
if (Math.max(visibleStartSec, mdTime.start - TRACE_MARGIN_TIME_S) <
Math.min(visibleEndSec, mdTime.end + TRACE_MARGIN_TIME_S)) {
visibleStartSec =
Math.max(visibleStartSec, mdTime.start - TRACE_MARGIN_TIME_S);
visibleEndSec = Math.min(visibleEndSec, mdTime.end + TRACE_MARGIN_TIME_S);
}
return [visibleStartSec, visibleEndSec];
}