com.peterphi.std.threading.Deadline Maven / Gradle / Ivy
package com.peterphi.std.threading;
import org.apache.log4j.Logger;
import java.io.Serializable;
import java.util.Calendar;
import java.util.Date;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* Represents a deadline (some point in the future - generally, a time by which some operation should be completed)
*/
public final class Deadline implements Comparable, Serializable
{
/**
*
*/
private static final long serialVersionUID = 1L;
private static transient final Logger log = Logger.getLogger(Deadline.class);
/**
* A deadline which will never arrive - representing the year 292278994, on Sun Aug 17 at 07:12:55 UTC
*/
public static final Deadline MAX_VALUE = new Deadline(Long.MAX_VALUE);
/**
* The current deadline (in milliseconds since 1970 UTC)
*/
private final long deadline;
/**
* Constructs a new deadline based on adding timeout to the current time
* If current time + timeout > Long.MAX_VALUE then Long.MAX_VALUE is used as the deadline
*
* @param timeout
*/
public Deadline(final Timeout timeout)
{
final long now = System.currentTimeMillis();
final long proposed = now + timeout.getMilliseconds();
if (proposed >= now)
this.deadline = proposed;
else
this.deadline = Long.MAX_VALUE;
if (this.deadline < 0)
throw new IllegalStateException("Deadline has a negative value!");
}
/**
* @param timestamp
*/
public Deadline(final long timestamp)
{
if (timestamp < 0)
throw new IllegalArgumentException("Must provide a positive timestamp for deadline!");
this.deadline = timestamp;
}
/**
* Constructs a deadline using a given period of time
*
* @param timeout
* @param unit
*/
public Deadline(final long timeout, final TimeUnit unit)
{
this(new Timeout(timeout, unit));
}
public Deadline(final Calendar calendar)
{
this(calendar.getTimeInMillis());
}
public Deadline(final Date date)
{
this(date.getTime());
}
/**
* Determines whether the deadline has expired yet
*
* @return
*/
public boolean isExpired()
{
return System.currentTimeMillis() >= deadline;
}
/**
* Determine whether the deadline is still valid (ie. has not expired yet)
*
* @return
*/
public boolean isValid()
{
return System.currentTimeMillis() < deadline;
}
/**
* Determines the amount of time leftuntil the deadline and returns it as a timeout
*
* @return a timeout representing the amount of time remaining until this deadline expires
*/
public Timeout getTimeoutLeft()
{
final long left = getTimeLeft();
if (left != 0)
return new Timeout(left, TimeUnit.MILLISECONDS);
else
return Timeout.ZERO;
}
/**
* Determines the amount of time left (in milliseconds) until the deadline; if the deadline has been reached or passed this
* method returns 0
*
* @return the number of milliseconds left until this deadline expires
*/
public long getTimeLeft()
{
final long left = deadline - System.currentTimeMillis();
if (left > 0)
return left;
else
return 0;
}
/**
* Returns the time represented by this deadline as a Date
*
* @return
*/
public Date getDate()
{
return new Date(this.deadline);
}
/**
* Determines the amount of time left (in a custom unit) until the deadline; if the deadline has been reached or passed this
* method returns 0
*
* @param unit
* a unit of time
*
* @return the amount of time left before this deadline expires, converted (using TimeUnit.convert) into the
* given Time Unit
*/
public long getTimeLeft(final TimeUnit unit)
{
final long left = unit.convert(getTimeLeft(), TimeUnit.MILLISECONDS);
if (left > 0)
return left;
else
return 0;
}
/**
* Sleeps the current thread until interrupted or until this deadline has expired. Returns this no matter what
* condition causes this method's termination
* This is essentially a neater way of calling Thread.sleep
*
* @return itself
*/
public Deadline sleep()
{
try
{
Thread.sleep(getTimeLeft(TimeUnit.MILLISECONDS));
}
catch (InterruptedException e)
{
// ignore
}
return this;
}
/**
* Sleeps the current thread until this deadline has expired; if mayInterrupt is true then an interrupt will
* cause this method to return true
* This is essentially a neater way of calling Thread.sleep
*
* @param mayInterrupt
* whether this method may be interrupted by an InterruptedException
*
* @return whether the sleep was ended early by an interrupt
*/
public boolean sleep(final boolean mayInterrupt)
{
while (isValid())
{
try
{
Thread.sleep(getTimeLeft(TimeUnit.MILLISECONDS));
}
catch (InterruptedException e)
{
if (mayInterrupt)
return true;
}
}
return false;
}
/**
* Waits on the listed monitor until it returns or until this deadline has expired; if mayInterrupt is true then
* an interrupt will cause this method to return true
*
* @param ignoreInterrupts
* false if the code should return early in the event of an interrupt, otherwise true if InterruptedExceptions should be
* ignored
*/
public void waitFor(final Object monitor, final boolean ignoreInterrupts)
{
synchronized (monitor)
{
try
{
monitor.wait(this.getTimeLeft(TimeUnit.MILLISECONDS));
}
catch (InterruptedException e)
{
if (!ignoreInterrupts)
return;
}
}
return;
}
/**
* Resolves a Future, automatically cancelling it in the event of a timeout / failure
*
* @param
* @param future
*
* @return
*
* @throws RuntimeException
*/
public T resolveFuture(final Future future) throws RuntimeException
{
return resolveFuture(future, true);
}
/**
* Resolves a Future, potentially automatically cancelling it in the event of a timeout / failure
*
* @param
* the return type
* @param future
* @param autocancel
* if the thread should be cancelled if the deadline expires within this method
*
* @return the resolved value of the future (or null in the event of a timeout)
*
* @throws RuntimeException
* if the operation fails (or is cancelled by another party)
*/
public T resolveFuture(final Future future, final boolean autocancel) throws RuntimeException
{
while (isValid() && !future.isCancelled())
{
try
{
return future.get(getTimeLeft(), TimeUnit.MILLISECONDS);
}
catch (InterruptedException e)
{
// ignore and start waiting again
}
catch (ExecutionException e)
{
try
{
if (autocancel)
future.cancel(true);
}
catch (Throwable t)
{
log.info("{resolveFuture} Error auto-cancelling after ExecutionException: " + t.getMessage(), t);
}
throw new RuntimeException(e);
}
catch (TimeoutException e)
{
break;
}
}
// We timed out
future.cancel(true);
return null;
}
@Override
public int compareTo(Deadline that)
{
final Long thisDeadline = Long.valueOf(deadline);
return thisDeadline.compareTo(that.deadline);
}
@Override
public int hashCode()
{
// return the hashcode of the Long
return (int) (deadline ^ (deadline >>> 32));
}
@Override
public boolean equals(final Object o)
{
if (this == o)
return true;
else if (o == null)
return false;
else if (o.getClass().equals(Deadline.class))
{
final Deadline that = (Deadline) o;
return this.deadline == that.deadline;
}
else
{
return false;
}
}
/**
* @see java.lang.Object#toString()
*/
@Override
public String toString()
{
return "[Deadline " + new Date(deadline) + ", msLeft=" + this.getTimeLeft() + "]";
}
/**
* Retrieve the deadline with the least time remaining until it expires
*
* @param deadlines
*
* @return
*/
public static Deadline soonest(Deadline... deadlines)
{
Deadline min = null;
if (deadlines != null)
for (Deadline deadline : deadlines)
{
if (deadline != null)
{
if (min == null)
min = deadline;
else if (deadline.getTimeLeft() < min.getTimeLeft())
{
min = deadline;
}
}
}
return min;
}
/**
* Retrieve the deadline with the most time remaining until it expires
*
* @param deadlines
*
* @return
*/
public static Deadline latest(Deadline... deadlines)
{
Deadline max = null;
if (deadlines != null)
for (Deadline deadline : deadlines)
{
if (max == null)
max = deadline;
else if (deadline.getTimeLeft() > max.getTimeLeft())
{
max = deadline;
}
}
return max;
}
}
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