signal-desktop/js/calling-tools/data_series.js
2024-05-23 15:19:12 -07:00

133 lines
3.5 KiB
JavaScript

// Derived from Chromium WebRTC Internals Dashboard - see Acknowledgements for full license details
// The maximum number of data points buffered for each stats. Old data points
// will be shifted out when the buffer is full.
export const MAX_STATS_DATA_POINT_BUFFER_SIZE = 1000;
/**
* A TimelineDataSeries collects an ordered series of (time, value) pairs,
* and converts them to graph points. It also keeps track of its color and
* current visibility state.
* It keeps MAX_STATS_DATA_POINT_BUFFER_SIZE data points at most. Old data
* points will be dropped when it reaches this size.
*/
export class TimelineDataSeries {
constructor(statsType) {
// List of DataPoints in chronological order.
this.dataPoints_ = [];
// Default color. Should always be overridden prior to display.
this.color_ = 'red';
// Whether or not the data series should be drawn.
this.isVisible_ = true;
this.cacheStartTime_ = null;
this.cacheStepSize_ = 0;
this.cacheValues_ = [];
this.statsType_ = statsType;
}
/**
* @override
*/
toJSON() {
if (this.dataPoints_.length < 1) {
return {};
}
const values = [];
for (let i = 0; i < this.dataPoints_.length; ++i) {
values.push(this.dataPoints_[i].value);
}
return {
startTime: this.dataPoints_[0].time,
endTime: this.dataPoints_[this.dataPoints_.length - 1].time,
statsType: this.statsType_,
values: JSON.stringify(values),
};
}
/**
* Adds a DataPoint to |this| with the specified time and value.
* DataPoints are assumed to be received in chronological order.
*/
addPoint(timeTicks, value) {
const time = new Date(timeTicks);
this.dataPoints_.push(new DataPoint(time, value));
if (this.dataPoints_.length > MAX_STATS_DATA_POINT_BUFFER_SIZE) {
this.dataPoints_.shift();
}
}
isVisible() {
return this.isVisible_;
}
show(isVisible) {
this.isVisible_ = isVisible;
}
getColor() {
return this.color_;
}
setColor(color) {
this.color_ = color;
}
getCount() {
return this.dataPoints_.length;
}
/**
* Returns a list containing the values of the data series at |count|
* points, starting at |startTime|, and |stepSize| milliseconds apart.
* Caches values, so showing/hiding individual data series is fast.
*/
getValues(startTime, stepSize, count) {
// Use cached values, if we can.
if (this.cacheStartTime_ === startTime &&
this.cacheStepSize_ === stepSize &&
this.cacheValues_.length === count) {
return this.cacheValues_;
}
// Do all the work.
this.cacheValues_ = this.getValuesInternal_(startTime, stepSize, count);
this.cacheStartTime_ = startTime;
this.cacheStepSize_ = stepSize;
return this.cacheValues_;
}
/**
* Returns the cached |values| in the specified time period.
*/
getValuesInternal_(startTime, stepSize, count) {
const values = [];
let nextPoint = 0;
let currentValue = 0;
let time = startTime;
for (let i = 0; i < count; ++i) {
while (nextPoint < this.dataPoints_.length &&
this.dataPoints_[nextPoint].time < time) {
currentValue = this.dataPoints_[nextPoint].value;
++nextPoint;
}
values[i] = currentValue;
time += stepSize;
}
return values;
}
}
/**
* A single point in a data series. Each point has a time, in the form of
* milliseconds since the Unix epoch, and a numeric value.
*/
class DataPoint {
constructor(time, value) {
this.time = time;
this.value = value;
}
}