package io.prometheus.client;
import io.prometheus.client.CKMSQuantiles.Quantile;
import java.io.Closeable;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.concurrent.TimeUnit;
/**
* Summary metric, to track the size of events.
* <p>
* Example of uses for Summaries include:
* <ul>
* <li>Response latency</li>
* <li>Request size</li>
* </ul>
*
* <p>
* Example Summaries:
* <pre>
* {@code
* class YourClass {
* static final Summary receivedBytes = Summary.build()
* .name("requests_size_bytes").help("Request size in bytes.").register();
* static final Summary requestLatency = Summary.build()
* .name("requests_latency_seconds").help("Request latency in seconds.").register();
*
* void processRequest(Request req) {
* Summary.Timer requestTimer = requestLatency.startTimer();
* try {
* // Your code here.
* } finally {
* receivedBytes.observe(req.size());
* requestTimer.observeDuration();
* }
* }
*
* // Or if using Java 8 and lambdas.
* void processRequestLambda(Request req) {
* receivedBytes.observe(req.size());
* requestLatency.time(() -> {
* // Your code here.
* });
* }
* }
* }
* </pre>
* This would allow you to track request rate, average latency and average request size.
*
* <p>
* How to add custom quantiles:
* <pre>
* {@code
* static final Summary myMetric = Summary.build()
* .quantile(0.5, 0.05) // Add 50th percentile (= median) with 5% tolerated error
* .quantile(0.9, 0.01) // Add 90th percentile with 1% tolerated error
* .quantile(0.99, 0.001) // Add 99th percentile with 0.1% tolerated error
* .name("requests_size_bytes")
* .help("Request size in bytes.")
* .register();
* }
* </pre>
*
* The quantiles are calculated over a sliding window of time. There are two options to configure this time window:
* <ul>
* <li>maxAgeSeconds(long): Set the duration of the time window is, i.e. how long observations are kept before they are discarded.
* Default is 10 minutes.
* <li>ageBuckets(int): Set the number of buckets used to implement the sliding time window. If your time window is 10 minutes, and you have ageBuckets=5,
* buckets will be switched every 2 minutes. The value is a trade-off between resources (memory and cpu for maintaining the bucket)
* and how smooth the time window is moved. Default value is 5.
* </ul>
*
* See https://prometheus.io/docs/practices/histograms/ for more info on quantiles.
*/
public class Summary extends SimpleCollector<Summary.Child> implements Counter.Describable {
final List<Quantile> quantiles; // Can be empty, but can never be null.
final long maxAgeSeconds;
final int ageBuckets;
Summary(Builder b) {
super(b);
quantiles = Collections.unmodifiableList(new ArrayList<Quantile>(b.quantiles));
this.maxAgeSeconds = b.maxAgeSeconds;
this.ageBuckets = b.ageBuckets;
initializeNoLabelsChild();
}
public static class Builder extends SimpleCollector.Builder<Builder, Summary> {
private final List<Quantile> quantiles = new ArrayList<Quantile>();
private long maxAgeSeconds = TimeUnit.MINUTES.toSeconds(10);
private int ageBuckets = 5;
public Builder quantile(double quantile, double error) {
if (quantile < 0.0 || quantile > 1.0) {
throw new IllegalArgumentException("Quantile " + quantile + " invalid: Expected number between 0.0 and 1.0.");
}
if (error < 0.0 || error > 1.0) {
throw new IllegalArgumentException("Error " + error + " invalid: Expected number between 0.0 and 1.0.");
}
quantiles.add(new Quantile(quantile, error));
return this;
}
public Builder maxAgeSeconds(long maxAgeSeconds) {
if (maxAgeSeconds <= 0) {
throw new IllegalArgumentException("maxAgeSeconds cannot be " + maxAgeSeconds);
}
this.maxAgeSeconds = maxAgeSeconds;
return this;
}
public Builder ageBuckets(int ageBuckets) {
if (ageBuckets <= 0) {
throw new IllegalArgumentException("ageBuckets cannot be " + ageBuckets);
}
this.ageBuckets = ageBuckets;
return this;
}
@Override
public Summary create() {
for (String label : labelNames) {
if (label.equals("quantile")) {
throw new IllegalStateException("Summary cannot have a label named 'quantile'.");
}
}
dontInitializeNoLabelsChild = true;
return new Summary(this);
}
}
/**
* Return a Builder to allow configuration of a new Summary. Ensures required fields are provided.
*
* @param name The name of the metric
* @param help The help string of the metric
*/
public static Builder build(String name, String help) {
return new Builder().name(name).help(help);
}
/**
* Return a Builder to allow configuration of a new Summary.
*/
public static Builder build() {
return new Builder();
}
@Override
protected Child newChild() {
return new Child(quantiles, maxAgeSeconds, ageBuckets);
}
/**
* Represents an event being timed.
*/
public static class Timer implements Closeable {
private final Child child;
private final long start;
private Timer(Child child, long start) {
this.child = child;
this.start = start;
}
/**
* Observe the amount of time in seconds since {@link Child#startTimer} was called.
* @return Measured duration in seconds since {@link Child#startTimer} was called.
*/
public double observeDuration() {
double elapsed = SimpleTimer.elapsedSecondsFromNanos(start, SimpleTimer.defaultTimeProvider.nanoTime());
child.observe(elapsed);
return elapsed;
}
/**
* Equivalent to calling {@link #observeDuration()}.
* @throws IOException
*/
@Override
public void close() throws IOException {
observeDuration();
}
}
/**
* The value of a single Summary.
* <p>
* <em>Warning:</em> References to a Child become invalid after using
* {@link SimpleCollector#remove} or {@link SimpleCollector#clear}.
*/
public static class Child {
/**
* Executes runnable code (i.e. a Java 8 Lambda) and observes a duration of how long it took to run.
*
* @param timeable Code that is being timed
* @return Measured duration in seconds for timeable to complete.
*/
public double time(Runnable timeable) {
Timer timer = startTimer();
double elapsed;
try {
timeable.run();
} finally {
elapsed = timer.observeDuration();
}
return elapsed;
}
public static class Value {
public final double count;
public final double sum;
public final SortedMap<Double, Double> quantiles;
private Value(double count, double sum, List<Quantile> quantiles, TimeWindowQuantiles quantileValues) {
this.count = count;
this.sum = sum;
this.quantiles = Collections.unmodifiableSortedMap(snapshot(quantiles, quantileValues));
}
private SortedMap<Double, Double> snapshot(List<Quantile> quantiles, TimeWindowQuantiles quantileValues) {
SortedMap<Double, Double> result = new TreeMap<Double, Double>();
for (Quantile q : quantiles) {
result.put(q.quantile, quantileValues.get(q.quantile));
}
return result;
}
}
// Having these separate leaves us open to races,
// however Prometheus as whole has other races
// that mean adding atomicity here wouldn't be useful.
// This should be reevaluated in the future.
private final DoubleAdder count = new DoubleAdder();
private final DoubleAdder sum = new DoubleAdder();
private final List<Quantile> quantiles;
private final TimeWindowQuantiles quantileValues;
private Child(List<Quantile> quantiles, long maxAgeSeconds, int ageBuckets) {
this.quantiles = quantiles;
if (quantiles.size() > 0) {
quantileValues = new TimeWindowQuantiles(quantiles.toArray(new Quantile[]{}), maxAgeSeconds, ageBuckets);
} else {
quantileValues = null;
}
}
/**
* Observe the given amount.
*/
public void observe(double amt) {
count.add(1);
sum.add(amt);
if (quantileValues != null) {
quantileValues.insert(amt);
}
}
/**
* Start a timer to track a duration.
* <p>
* Call {@link Timer#observeDuration} at the end of what you want to measure the duration of.
*/
public Timer startTimer() {
return new Timer(this, SimpleTimer.defaultTimeProvider.nanoTime());
}
/**
* Get the value of the Summary.
* <p>
* <em>Warning:</em> The definition of {@link Value} is subject to change.
*/
public Value get() {
return new Value(count.sum(), sum.sum(), quantiles, quantileValues);
}
}
// Convenience methods.
/**
* Observe the given amount on the summary with no labels.
*/
public void observe(double amt) {
noLabelsChild.observe(amt);
}
/**
* Start a timer to track a duration on the summary with no labels.
* <p>
* Call {@link Timer#observeDuration} at the end of what you want to measure the duration of.
*/
public Timer startTimer() {
return noLabelsChild.startTimer();
}
/**
* Executes runnable code (i.e. a Java 8 Lambda) and observes a duration of how long it took to run.
*
* @param timeable Code that is being timed
* @return Measured duration in seconds for timeable to complete.
*/
public double time(Runnable timeable){
return noLabelsChild.time(timeable);
}
/**
* Get the value of the Summary.
* <p>
* <em>Warning:</em> The definition of {@link Child.Value} is subject to change.
*/
public Child.Value get() {
return noLabelsChild.get();
}
@Override
public List<MetricFamilySamples> collect() {
List<MetricFamilySamples.Sample> samples = new ArrayList<MetricFamilySamples.Sample>();
for(Map.Entry<List<String>, Child> c: children.entrySet()) {
Child.Value v = c.getValue().get();
List<String> labelNamesWithQuantile = new ArrayList<String>(labelNames);
labelNamesWithQuantile.add("quantile");
for(Map.Entry<Double, Double> q : v.quantiles.entrySet()) {
List<String> labelValuesWithQuantile = new ArrayList<String>(c.getKey());
labelValuesWithQuantile.add(doubleToGoString(q.getKey()));
samples.add(new MetricFamilySamples.Sample(fullname, labelNamesWithQuantile, labelValuesWithQuantile, q.getValue()));
}
samples.add(new MetricFamilySamples.Sample(fullname + "_count", labelNames, c.getKey(), v.count));
samples.add(new MetricFamilySamples.Sample(fullname + "_sum", labelNames, c.getKey(), v.sum));
}
return familySamplesList(Type.SUMMARY, samples);
}
@Override
public List<MetricFamilySamples> describe() {
return Collections.<MetricFamilySamples>singletonList(new SummaryMetricFamily(fullname, help, labelNames));
}
}