com.codahale.metrics.Timer Maven / Gradle / Ivy
package com.codahale.metrics;
import java.io.Closeable;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
/**
* A timer metric which aggregates timing durations and provides duration statistics, plus
* throughput statistics via {@link Meter}.
*/
public class Timer implements Metered, Sampling {
/**
* A timing context.
*
* @see Timer#time()
*/
public static class Context implements Closeable {
private final Timer timer;
private final Clock clock;
private final long startTime;
private Context(Timer timer, Clock clock) {
this.timer = timer;
this.clock = clock;
this.startTime = clock.getTick();
}
/**
* Updates the timer with the difference between current and start time. Call to this method will
* not reset the start time. Multiple calls result in multiple updates.
* @return the elapsed time in nanoseconds
*/
public long stop() {
final long elapsed = clock.getTick() - startTime;
timer.update(elapsed, TimeUnit.NANOSECONDS);
return elapsed;
}
/** Equivalent to calling {@link #stop()}. */
@Override
public void close() {
stop();
}
}
private final Meter meter;
private final Histogram histogram;
private final Clock clock;
/**
* Creates a new {@link Timer} using an {@link ExponentiallyDecayingReservoir} and the default
* {@link Clock}.
*/
public Timer() {
this(new ExponentiallyDecayingReservoir());
}
/**
* Creates a new {@link Timer} that uses the given {@link Reservoir}.
*
* @param reservoir the {@link Reservoir} implementation the timer should use
*/
public Timer(Reservoir reservoir) {
this(reservoir, Clock.defaultClock());
}
/**
* Creates a new {@link Timer} that uses the given {@link Reservoir} and {@link Clock}.
*
* @param reservoir the {@link Reservoir} implementation the timer should use
* @param clock the {@link Clock} implementation the timer should use
*/
public Timer(Reservoir reservoir, Clock clock) {
this.meter = new Meter(clock);
this.clock = clock;
this.histogram = new Histogram(reservoir);
}
/**
* Adds a recorded duration.
*
* @param duration the length of the duration
* @param unit the scale unit of {@code duration}
*/
public void update(long duration, TimeUnit unit) {
update(unit.toNanos(duration));
}
/**
* Times and records the duration of event.
*
* @param event a {@link Callable} whose {@link Callable#call()} method implements a process
* whose duration should be timed
* @param the type of the value returned by {@code event}
* @return the value returned by {@code event}
* @throws Exception if {@code event} throws an {@link Exception}
*/
public T time(Callable event) throws Exception {
final long startTime = clock.getTick();
try {
return event.call();
} finally {
update(clock.getTick() - startTime);
}
}
/**
* Returns a new {@link Context}.
*
* @return a new {@link Context}
* @see Context
*/
public Context time() {
return new Context(this, clock);
}
@Override
public long getCount() {
return histogram.getCount();
}
@Override
public double getFifteenMinuteRate() {
return meter.getFifteenMinuteRate();
}
@Override
public double getFiveMinuteRate() {
return meter.getFiveMinuteRate();
}
@Override
public double getMeanRate() {
return meter.getMeanRate();
}
@Override
public double getOneMinuteRate() {
return meter.getOneMinuteRate();
}
@Override
public Snapshot getSnapshot() {
return histogram.getSnapshot();
}
private void update(long duration) {
if (duration >= 0) {
histogram.update(duration);
meter.mark();
}
}
}