io.prometheus.client.exemplars.Exemplar 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.exemplars;

import java.util.Arrays;
import java.util.Map;
import java.util.regex.Pattern;

/**
 * Immutable data class holding an Exemplar.
 */
public class Exemplar {

  private final String[] labels;
  private final double value;
  private final Long timestampMs;

  private static final Pattern labelNameRegex = Pattern.compile("[a-zA-Z_][a-zA-Z_0-9]*");

  /**
   * Create an Exemplar without a timestamp
   *
   * @param value  the observed value
   * @param labels name/value pairs. Expecting an even number of strings. The combined length of the label names and
   *               values must not exceed 128 UTF-8 characters. Neither a label name nor a label value may be null.
   */
  public Exemplar(double value, String... labels) {
    this(value, null, labels);
  }

  /**
   * Create an Exemplar
   *
   * @param value       the observed value
   * @param timestampMs as in {@link System#currentTimeMillis()}
   * @param labels      name/value pairs. Expecting an even number of strings. The combined length of the
   *                    label names and values must not exceed 128 UTF-8 characters. Neither a label name
   *                    nor a label value may be null.
   */
  public Exemplar(double value, Long timestampMs, String... labels) {
    this.labels = sortedCopy(labels);
    this.value = value;
    this.timestampMs = timestampMs;
  }

  /**
   * Create an Exemplar
   *
   * @param value  the observed value
   * @param labels the labels. Must not be null. The combined length of the label names and values must not exceed
   *               128 UTF-8 characters. Neither a label name nor a label value may be null.
   */
  public Exemplar(double value, Map labels) {
    this(value, null, mapToArray(labels));
  }

  /**
   * Create an Exemplar
   *
   * @param value       the observed value
   * @param timestampMs as in {@link System#currentTimeMillis()}
   * @param labels      the labels. Must not be null. The combined length of the label names and values must not exceed
   *                    128 UTF-8 characters. Neither a label name nor a label value may be null.
   */
  public Exemplar(double value, Long timestampMs, Map labels) {
    this(value, timestampMs, mapToArray(labels));
  }

  public int getNumberOfLabels() {
    return labels.length / 2;
  }

  /**
   * Get the label name at index {@code i}.
   * @param i the index, must be >= 0 and < {@link #getNumberOfLabels()}.
   * @return the label name at index {@code i}
   */
  public String getLabelName(int i) {
    return labels[2 * i];
  }

  /**
   * Get the label value at index {@code i}.
   * @param i the index, must be >= 0 and < {@link #getNumberOfLabels()}.
   * @return the label value at index {@code i}
   */
  public String getLabelValue(int i) {
    return labels[2 * i + 1];
  }

  public double getValue() {
    return value;
  }

  /**
   * @return Unix timestamp or {@code null} if no timestamp is present.
   */
  public Long getTimestampMs() {
    return timestampMs;
  }

  private String[] sortedCopy(String... labels) {
    if (labels.length % 2 != 0) {
      throw new IllegalArgumentException("labels are name/value pairs, expecting an even number");
    }
    String[] result = new String[labels.length];
    int charsTotal = 0;
    for (int i = 0; i < labels.length; i+=2) {
      if (labels[i] == null) {
        throw new IllegalArgumentException("labels[" + i + "] is null");
      }
      if (labels[i+1] == null) {
        throw new IllegalArgumentException("labels[" + (i+1) + "] is null");
      }
      if (!labelNameRegex.matcher(labels[i]).matches()) {
        throw new IllegalArgumentException(labels[i] + " is not a valid label name");
      }
      result[i] = labels[i]; // name
      result[i+1] = labels[i+1]; // value
      charsTotal += labels[i].length() + labels[i+1].length();
      // Move the current tuple down while the previous name is greater than current name.
      for (int j=i-2; j>=0; j-=2) {
        int compareResult = result[j+2].compareTo(result[j]);
        if (compareResult == 0) {
          throw new IllegalArgumentException(result[j] + ": label name is not unique");
        } else if (compareResult < 0) {
          String tmp = result[j];
          result[j] = result[j+2];
          result[j+2] = tmp;
          tmp = result[j+1];
          result[j+1] = result[j+3];
          result[j+3] = tmp;
        } else {
          break;
        }
      }
    }
    if (charsTotal > 128) {
      throw new IllegalArgumentException(
          "the combined length of the label names and values must not exceed 128 UTF-8 characters");
    }
    return result;
  }

  /**
   * Convert the map to an array {@code [key1, value1, key2, value2, ...]}.
   */
  public static String[] mapToArray(Map labelMap) {
    if (labelMap == null) {
      return null;
    }
    String[] result = new String[2 * labelMap.size()];
    int i = 0;
    for (Map.Entry entry : labelMap.entrySet()) {
      result[i] = entry.getKey();
      result[i + 1] = entry.getValue();
      i += 2;
    }
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (!(obj instanceof Exemplar)) {
      return false;
    }
    Exemplar other = (Exemplar) obj;
    return Arrays.equals(this.labels, other.labels) &&
        Double.compare(other.value, value) == 0 &&
        (timestampMs == null && other.timestampMs == null
            || timestampMs != null && timestampMs.equals(other.timestampMs));
  }

  @Override
  public int hashCode() {
    int hash = Arrays.hashCode(labels);
    long d = Double.doubleToLongBits(value);
    hash = 37 * hash + (int) (d ^ (d >>> 32));
    if (timestampMs != null) {
      hash = 37 * hash + timestampMs.intValue();
    }
    return hash;
  }
}