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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
/* eslint-env worker */
/**
* Import `createTask` to communicate with `devtools/shared/worker`.
*/
importScripts("resource://gre/modules/workers/require.js");
const { createTask } = require("resource://devtools/shared/worker/helper.js");
/**
* @see LineGraphWidget.prototype.setDataFromTimestamps in Graphs.js
* @param number id
* @param array timestamps
* @param number interval
* @param number duration
*/
createTask(self, "plotTimestampsGraph", function ({ timestamps,
interval, duration }) {
let plottedData = plotTimestamps(timestamps, interval);
let plottedMinMaxSum = getMinMaxAvg(plottedData, timestamps, duration);
return { plottedData, plottedMinMaxSum };
});
/**
* Gets the min, max and average of the values in an array.
* @param array source
* @param array timestamps
* @param number duration
* @return object
*/
function getMinMaxAvg(source, timestamps, duration) {
let totalFrames = timestamps.length;
let maxValue = Number.MIN_SAFE_INTEGER;
let minValue = Number.MAX_SAFE_INTEGER;
// Calculate the average by counting how many frames occurred
// in the duration of the recording, rather than average the frame points
// we have, as that weights higher FPS, as there'll be more timestamps for
// those values
let avgValue = totalFrames / (duration / 1000);
for (let { value } of source) {
maxValue = Math.max(value, maxValue);
minValue = Math.min(value, minValue);
}
return { minValue, maxValue, avgValue };
}
/**
* Takes a list of numbers and plots them on a line graph representing
* the rate of occurences in a specified interval.
*
* @param array timestamps
* A list of numbers representing time, ordered ascending. For example,
* this can be the raw data received from the framerate actor, which
* represents the elapsed time on each refresh driver tick.
* @param number interval
* The maximum amount of time to wait between calculations.
* @param number clamp
* The maximum allowed value.
* @return array
* A collection of { delta, value } objects representing the
* plotted value at every delta time.
*/
function plotTimestamps(timestamps, interval = 100, clamp = 60) {
let timeline = [];
let totalTicks = timestamps.length;
// If the refresh driver didn't get a chance to tick before the
// recording was stopped, assume rate was 0.
if (totalTicks == 0) {
timeline.push({ delta: 0, value: 0 });
timeline.push({ delta: interval, value: 0 });
return timeline;
}
let frameCount = 0;
let prevTime = +timestamps[0];
for (let i = 1; i < totalTicks; i++) {
let currTime = +timestamps[i];
frameCount++;
let elapsedTime = currTime - prevTime;
if (elapsedTime < interval) {
continue;
}
let rate = Math.min(1000 / (elapsedTime / frameCount), clamp);
timeline.push({ delta: prevTime, value: rate });
timeline.push({ delta: currTime, value: rate });
frameCount = 0;
prevTime = currTime;
}
return timeline;
}
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