95 lines
3.4 KiB
JavaScript
95 lines
3.4 KiB
JavaScript
/**
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* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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// StatTracker is a helper class to keep track of stats on a RTCPeerConnection
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// object. It uses google visualization datatables to keep the recorded samples
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// and simplify plugging them into graphs later.
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//
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// Usage example:
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// var tracker = new StatTracker(pc, pollInterval);
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// tracker.recordStat("EstimatedSendBitrate",
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// "bweforvideo", "googAvailableSendBandwidth");
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// ...
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// tracker.stop();
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// tracker.dataTable(); // returns the recorded values. In this case
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// a table with 2 columns { Time, EstimatedSendBitrate } and a row for each
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// sample taken until stop() was called.
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//
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function StatTracker(pc, pollInterval) {
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pollInterval = pollInterval || 250;
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var dataTable = new google.visualization.DataTable();
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var timeColumnIndex = dataTable.addColumn('datetime', 'Time');
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var recording = true;
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// Set of sampling functions. Functions registered here are called
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// once per getStats with the given report and a rowIndex for the
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// sample period so they can extract and record the tracked variables.
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var samplingFunctions = {};
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// Accessor to the current recorded stats.
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this.dataTable = function() { return dataTable; }
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// recordStat(varName, recordName, statName) adds a samplingFunction that
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// records namedItem(recordName).stat(statName) from RTCStatsReport for each
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// sample into a column named varName in the dataTable.
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this.recordStat = function (varName, recordName, statName) {
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var columnIndex = dataTable.addColumn('number', varName);
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samplingFunctions[varName] = function (report, rowIndex) {
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var sample;
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var record = report.namedItem(recordName);
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if (record) sample = record.stat(statName);
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dataTable.setCell(rowIndex, columnIndex, sample);
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}
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}
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// Stops the polling of stats from the peer connection.
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this.stop = function() {
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recording = false;
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}
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// RTCPeerConnection.getStats is asynchronous. In order to avoid having
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// too many pending getStats requests going, this code only queues the
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// next getStats with setTimeout after the previous one returns, instead
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// of using setInterval.
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function poll() {
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pc.getStats(function (report) {
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if (!recording) return;
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setTimeout(poll, pollInterval);
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var result = report.result();
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if (result.length < 1) return;
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var rowIndex = dataTable.addRow();
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dataTable.setCell(rowIndex, timeColumnIndex, result[0].timestamp);
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for (var v in samplingFunctions)
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samplingFunctions[v](report, rowIndex);
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});
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}
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setTimeout(poll, pollInterval);
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}
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/**
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* Utility method to perform a full join between data tables from StatTracker.
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*/
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function mergeDataTable(dataTable1, dataTable2) {
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function allColumns(cols) {
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var a = [];
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for (var i = 1; i < cols; ++i) a.push(i);
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return a;
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}
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return google.visualization.data.join(
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dataTable1,
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dataTable2,
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'full',
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[[0, 0]],
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allColumns(dataTable1.getNumberOfColumns()),
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allColumns(dataTable2.getNumberOfColumns()));
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}
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