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Jenetics - Java Genetic Algorithm Library
/*
* Java Genetic Algorithm Library (jenetics-3.4.0).
* Copyright (c) 2007-2016 Franz Wilhelmstötter
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Author:
* Franz Wilhelmstötter ([email protected])
*/
package org.jenetics.engine;
import static java.util.Objects.requireNonNull;
import java.time.Clock;
import java.time.Duration;
import java.time.Instant;
import java.util.function.LongSupplier;
import org.jenetics.util.NanoClock;
/**
* Timer implementation for measuring execution durations.
*
* @author Franz Wilhelmstötter
* @since 3.0
* @version 3.1
*/
final class Timer {
private final LongSupplier _nanoClock;
private long _start;
private long _stop;
private Timer(final LongSupplier nanoClock) {
_nanoClock = requireNonNull(nanoClock);
}
/**
* Start the timer.
*
* @return {@code this} timer, for method chaining
*/
public Timer start() {
_start = _nanoClock.getAsLong();
return this;
}
/**
* Stop the timer.
*
* @return {@code this} timer, for method chaining
*/
public Timer stop() {
_stop = _nanoClock.getAsLong();
return this;
}
/**
* Return the duration between two consecutive {@link #start()} and
* {@link #stop()} calls.
*
* @return the duration between two {@code start} and {@code stop} calls
*/
public Duration getTime() {
return Duration.ofNanos(_stop - _start);
}
/**
* Return an new timer object which uses the given clock for measuring the
* execution time.
*
* @param clock the clock used for measuring the execution time
* @return a new timer
*/
public static Timer of(final Clock clock) {
requireNonNull(clock);
return clock instanceof NanoClock ? of() : new Timer(() -> nanos(clock));
}
private static long nanos(final Clock clock) {
final Instant now = clock.instant();
return now.getEpochSecond()*NanoClock.NANOS_PER_SECOND + now.getNano();
}
/**
* Return an new timer object with the default clock implementation.
*
* @return a new timer
*/
public static Timer of() {
return new Timer(System::nanoTime);
}
}
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