mirror of https://github.com/prometheus/prometheus
Update histogram math (#13680)
ui: Fix many edge cases of rendering a histogram --------- Signed-off-by: Manik Rana <manikrana54@gmail.com>pull/14416/head
Manik Rana
5 months ago
committed by
GitHub
parent
c94c5b64c3
commit
c9bc1c2be0
@ -0,0 +1,126 @@
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export type ScaleType = 'linear' | 'exponential';
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// Calculates a default width of exponential histogram bucket ranges. If the last bucket is [0, 0],
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// the width is calculated using the second to last bucket. returns error if the last bucket is [-0, 0],
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export function calculateDefaultExpBucketWidth(
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last: [number, string, string, string],
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buckets: [number, string, string, string][]
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): number {
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if (parseFloat(last[2]) === 0 || parseFloat(last[1]) === 0) {
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if (buckets.length > 1) {
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return Math.abs(
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Math.log(Math.abs(parseFloat(buckets[buckets.length - 2][2]))) -
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Math.log(Math.abs(parseFloat(buckets[buckets.length - 2][1])))
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);
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} else {
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throw new Error('Only one bucket in histogram ([-0, 0]). Cannot calculate defaultExpBucketWidth.');
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}
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} else {
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return Math.abs(Math.log(Math.abs(parseFloat(last[2]))) - Math.log(Math.abs(parseFloat(last[1]))));
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}
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}
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// Finds the lowest positive value from the bucket ranges
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// Returns 0 if no positive values are found or if there are no buckets.
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export function findMinPositive(buckets: [number, string, string, string][]) {
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if (!buckets || buckets.length === 0) {
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return 0; // no buckets
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}
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for (let i = 0; i < buckets.length; i++) {
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const right = parseFloat(buckets[i][2]);
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const left = parseFloat(buckets[i][1]);
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if (left > 0) {
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return left;
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}
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if (left < 0 && right > 0) {
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return right;
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}
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if (i === buckets.length - 1) {
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if (right > 0) {
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return right;
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}
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}
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}
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return 0; // all buckets are negative
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}
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// Finds the lowest negative value from the bucket ranges
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// Returns 0 if no negative values are found or if there are no buckets.
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export function findMaxNegative(buckets: [number, string, string, string][]) {
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if (!buckets || buckets.length === 0) {
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return 0; // no buckets
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}
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for (let i = 0; i < buckets.length; i++) {
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const right = parseFloat(buckets[i][2]);
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const left = parseFloat(buckets[i][1]);
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const prevRight = i > 0 ? parseFloat(buckets[i - 1][2]) : 0;
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if (right >= 0) {
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if (i === 0) {
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if (left < 0) {
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return left; // return the first negative bucket
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}
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return 0; // all buckets are positive
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}
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return prevRight; // return the last negative bucket
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}
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}
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console.log('findmaxneg returning: ', buckets[buckets.length - 1][2]);
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return parseFloat(buckets[buckets.length - 1][2]); // all buckets are negative
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}
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// Calculates the left position of the zero axis as a percentage string.
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export function findZeroAxisLeft(
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scale: ScaleType,
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rangeMin: number,
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rangeMax: number,
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minPositive: number,
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maxNegative: number,
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zeroBucketIdx: number,
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widthNegative: number,
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widthTotal: number,
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expBucketWidth: number
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): string {
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if (scale === 'linear') {
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return ((0 - rangeMin) / (rangeMax - rangeMin)) * 100 + '%';
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} else {
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if (maxNegative === 0) {
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return '0%';
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}
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if (minPositive === 0) {
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return '100%';
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}
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if (zeroBucketIdx === -1) {
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// if there is no zero bucket, we must zero axis between buckets around zero
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return (widthNegative / widthTotal) * 100 + '%';
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}
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if ((widthNegative + 0.5 * expBucketWidth) / widthTotal > 0) {
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return ((widthNegative + 0.5 * expBucketWidth) / widthTotal) * 100 + '%';
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} else {
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return '0%';
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}
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}
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}
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// Determines if the zero axis should be shown such that the zero label does not overlap with the range labels.
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// The zero axis is shown if it is between 5% and 95% of the graph.
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export function showZeroAxis(zeroAxisLeft: string) {
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const axisNumber = parseFloat(zeroAxisLeft.slice(0, -1));
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if (5 < axisNumber && axisNumber < 95) {
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return true;
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}
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return false;
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}
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// Finds the index of the bucket whose range includes zero
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export function findZeroBucket(buckets: [number, string, string, string][]): number {
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for (let i = 0; i < buckets.length; i++) {
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const left = parseFloat(buckets[i][1]);
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const right = parseFloat(buckets[i][2]);
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if (left <= 0 && right >= 0) {
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return i;
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}
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}
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return -1;
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}
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