com.rabbitmq.jms.util.TimeTracker Maven / Gradle / Ivy
/* Copyright (c) 2013 Pivotal Software, Inc. All rights reserved. */
package com.rabbitmq.jms.util;
import java.util.concurrent.TimeUnit;
/**
* Simple class to track elapsed time. Initialised with any time units, returns remaining time (in nanoseconds) on request.
*/
public class TimeTracker {
private final long timeoutNanos;
private final long startNanos;
private volatile boolean timed_out; /* becomes true and then sticks there */
/** Public tracker that is permanently timed out. */
public static final TimeTracker ZERO = new TimeTracker(0);
/**
* Initialise tracker with duration supplied.
* @param timeout - duration of tracker
* @param unit - units that timeout is in, e.g. TimeUnit.MILLISECONDS.
*/
public TimeTracker(long timeout, TimeUnit unit) {
this(unit.toNanos(timeout));
}
/**
* Initialise tracker with duration of old tracker (regardless that the old one has timed out).
* @param timeTracker - a TimeTracker instance
*/
public TimeTracker(TimeTracker timeTracker) {
this(timeTracker.timeoutNanos());
}
/**
* Initialise tracker with maximum duration -- effectively an infinite time.
*/
public TimeTracker() {
this(Long.MAX_VALUE);
}
/**
* Accessor for resurrecting a TimeTracker
* @return time originally set in nanoseconds
*/
long timeoutNanos() {
return this.timeoutNanos;
}
/**
* Initialise tracker with nanoseconds duration supplied.
* @param timeoutNanos - duration of tracker in nanoseconds
*/
private TimeTracker(long timeoutNanos) {
this.timeoutNanos = timeoutNanos;
this.startNanos = System.nanoTime();
this.timed_out = (timeoutNanos <= 0);
}
/**
* Return the remaining time to go in internal units, which are nanoseconds, or zero if there is no more.
* @return remaining time (in nanoseconds) - 0 means time has run out
*/
private long internalRemaining() {
if (this.timed_out) return 0;
long rem = this.timeoutNanos - (System.nanoTime() - this.startNanos);
if (rem<=0) {
this.timed_out = true;
return 0;
}
return rem;
}
/**
* Return the remaining time to go in nanoseconds, or zero if there is no more.
* @return remaining time (in nanoseconds) - 0 means time has run out
*/
public long remainingNanos() {
return this.internalRemaining();
}
/**
* Return the remaining time to go in milliseconds, or zero if there is no more.
* @return remaining time (in milliseconds) - 0 means time has run out
*/
public long remainingMillis() {
return TimeUnit.NANOSECONDS.toMillis(this.internalRemaining());
}
/**
* A {@link TimeUnit#timedWait} utility which uses the TimeTracker state.
*
* Used in synchronized(lock){} blocks that want to timeout based upon a time tracker object.
*
* @param lock - object to lock on
* @throws InterruptedException if the thread is interrupted while waiting.
*/
public void timedWait(Object lock) throws InterruptedException {
TimeUnit.NANOSECONDS.timedWait(lock, this.internalRemaining());
}
/**
* @return true if time has run out, false otherwise
*/
public boolean timedOut() {
return (this.timed_out || this.internalRemaining()==0);
}
@Override
public String toString() {
return (new StringBuilder("TimeTracker(")
.append(TimeUnit.NANOSECONDS.toMillis(timeoutNanos)) .append("ms set, ")
.append(TimeUnit.NANOSECONDS.toMillis(this.internalRemaining())).append("ms rem)")
).toString();
}
}