io.prometheus.client.TimeWindowQuantiles Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of simpleclient Show documentation

Core instrumentation library for the simpleclient.

The newest version!

package io.prometheus.client;

import io.prometheus.client.CKMSQuantiles.Quantile;
import java.util.concurrent.TimeUnit;

/**
 * Wrapper around CKMSQuantiles.
 *
 * Maintains a ring buffer of CKMSQuantiles to provide quantiles over a sliding windows of time.
 */
class TimeWindowQuantiles {

  private final Quantile[] quantiles;
  private final CKMSQuantiles[] ringBuffer;
  private int currentBucket;
  private long lastRotateTimestampMillis;
  private final long durationBetweenRotatesMillis;

  public TimeWindowQuantiles(Quantile[] quantiles, long maxAgeSeconds, int ageBuckets) {
    this.quantiles = quantiles;
    this.ringBuffer = new CKMSQuantiles[ageBuckets];
    for (int i = 0; i < ageBuckets; i++) {
      this.ringBuffer[i] = new CKMSQuantiles(quantiles);
    }
    this.currentBucket = 0;
    this.lastRotateTimestampMillis = System.currentTimeMillis();
    this.durationBetweenRotatesMillis = TimeUnit.SECONDS.toMillis(maxAgeSeconds) / ageBuckets;
  }

  public synchronized double get(double q) {
    CKMSQuantiles currentBucket = rotate();
    return currentBucket.get(q);
  }

  public synchronized void insert(double value) {
    rotate();
    for (CKMSQuantiles ckmsQuantiles : ringBuffer) {
      ckmsQuantiles.insert(value);
    }
  }

  private CKMSQuantiles rotate() {
    long timeSinceLastRotateMillis = System.currentTimeMillis() - lastRotateTimestampMillis;
    while (timeSinceLastRotateMillis > durationBetweenRotatesMillis) {
      ringBuffer[currentBucket] = new CKMSQuantiles(quantiles);
      if (++currentBucket >= ringBuffer.length) {
        currentBucket = 0;
      }
      timeSinceLastRotateMillis -= durationBetweenRotatesMillis;
      lastRotateTimestampMillis += durationBetweenRotatesMillis;
    }
    return ringBuffer[currentBucket];
  }
}