bd72e40e73
This patch introduces page.tracing, which allows to start and stop trace recording for a page. The trace could be then saved to file.
86 lines
2.4 KiB
JavaScript
86 lines
2.4 KiB
JavaScript
/**
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* Copyright 2017 Google Inc. All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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const fs = require('fs');
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const helper = require('./helper');
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class Tracing {
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/**
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* @param {!Connection} client
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*/
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constructor(client) {
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this._client = client;
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this._recording = false;
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}
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/**
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* @param {Object=} options
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*/
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async start(options = {}) {
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console.assert(!this._recording, 'Cannot start recording trace while already recording trace.');
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const categoriesArray = [
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'-*', 'devtools.timeline', 'v8.execute', 'disabled-by-default-devtools.timeline',
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'disabled-by-default-devtools.timeline.frame', 'toplevel',
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'blink.console', 'blink.user_timing', 'latencyInfo', 'disabled-by-default-devtools.timeline.stack',
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'disabled-by-default-v8.cpu_profiler'
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];
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if (options.screenshots)
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categoriesArray.push('disabled-by-default-devtools.screenshot');
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this._recording = true;
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await this._client.send('Tracing.start', {
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transferMode: 'ReturnAsStream',
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categories: categoriesArray.join(',')
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});
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}
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/**
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* @param {string} path
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*/
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async stop(path) {
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let fulfill;
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let contentPromise = new Promise(x => fulfill = x);
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this._client.once('Tracing.tracingComplete', event => {
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this._readStream(event.stream, path).then(fulfill);
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});
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await this._client.send('Tracing.end');
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this._recording = false;
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return contentPromise;
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}
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/**
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* @param {string} handle
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* @param {string=} path
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* @return {!Promise}
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*/
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async _readStream(handle, path) {
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let eof = false;
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let file = fs.openSync(path, 'w');
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while (!eof) {
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let response = await this._client.send('IO.read', {handle});
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eof = response.eof;
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if (path)
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fs.writeSync(file, response.data);
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}
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fs.closeSync(file);
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await this._client.send('IO.close', {handle});
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}
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}
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helper.tracePublicAPI(Tracing);
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module.exports = Tracing;
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