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Code cleanup and improved toString() and javadocs. 

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>
This commit is contained in:
Simone Bordet 2019-03-07 12:27:43 +01:00
parent 7bb1adb798
commit d2e13ec5ad
1 changed files with 35 additions and 20 deletions
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55
jetty-io/src/main/java/org/eclipse/jetty/io/CyclicTimeout.java
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@ -33,6 +33,20 @@ import static java.lang.Long.MAX_VALUE;
* <p>Subclasses should implement {@link #onTimeoutExpired()}.</p>
* <p>This implementation is optimised assuming that the timeout
* will mostly be cancelled and then reused with a similar value.</p>
* <p>This implementation has a {@link Timeout} holding the time
* at which the scheduled task should fire, and a linked list of
* {@link Wakeup}, each holding the actual scheduled task.</p>
* <p>Calling {@link #schedule(long, TimeUnit)} the first time will
* create a Timeout with an associated Wakeup and submit a task to
* the scheduler.
* Calling {@link #schedule(long, TimeUnit)} again with the same or
* a larger delay will cancel the previous Timeout, but keep the
* previous Wakeup without submitting a new task to the scheduler,
* therefore reducing the pressure on the scheduler and avoid it
* becomes a bottleneck.
* When the Wakeup task fires, it will see that the Timeout is now
* in the future and will attach a new Wakeup with the future time
* to the Timeout, and submit a scheduler task for the new Wakeup.</p>
*/
public abstract class CyclicTimeout implements Destroyable
{
@ -59,24 +73,24 @@ public abstract class CyclicTimeout implements Destroyable
}
/**
* Schedules a timeout, even if already set, cancelled or expired.
* <p>Schedules a timeout, even if already set, cancelled or expired.</p>
* <p>If a timeout is already set, it will be cancelled and replaced
* by the new one.</p>
*
* @param delay The period of time before the timeout expires.
* @param units The unit of time of the period.
* @return true if the timer was already set.
* @return true if the timeout was already set.
*/
public boolean schedule(long delay, TimeUnit units)
{
long now = System.nanoTime();
long new_timeout_at = now + units.toNanos(delay);
Wakeup new_wakeup = null;
boolean result;
Wakeup new_wakeup;
while (true)
{
Timeout timeout = _timeout.get();
new_wakeup = null;
result = timeout._at != MAX_VALUE;
// Is the current wakeup good to use? ie before our timeout time?
@ -114,14 +128,12 @@ public abstract class CyclicTimeout implements Destroyable
public boolean cancel()
{
boolean result;
Timeout timeout;
Timeout new_timeout;
while (true)
{
timeout = _timeout.get();
Timeout timeout = _timeout.get();
result = timeout._at != MAX_VALUE;
Wakeup wakeup = timeout._wakeup;
new_timeout = wakeup == null ? NOT_SET : new Timeout(MAX_VALUE, wakeup);
Timeout new_timeout = wakeup == null ? NOT_SET : new Timeout(MAX_VALUE, wakeup);
if (_timeout.compareAndSet(timeout, new_timeout))
break;
}
@ -166,7 +178,11 @@ public abstract class CyclicTimeout implements Destroyable
@Override
public String toString()
{
return String.format("%s@%x:%d,%s", getClass().getSimpleName(), hashCode(), _at, _wakeup);
return String.format("%s@%x:%dms,%s",
getClass().getSimpleName(),
hashCode(),
TimeUnit.NANOSECONDS.toMillis(_at - System.nanoTime()),
_wakeup);
}
}
@ -200,10 +216,9 @@ public abstract class CyclicTimeout implements Destroyable
@Override
public void run()
{
long now;
Wakeup new_wakeup;
boolean has_expired;
long now = System.nanoTime();
Wakeup new_wakeup = null;
boolean has_expired = false;
while (true)
{
Timeout timeout = _timeout.get();
@ -226,16 +241,12 @@ public abstract class CyclicTimeout implements Destroyable
// Not found, we become a noop.
return;
now = System.nanoTime();
new_wakeup = null;
has_expired = false;
Timeout new_timeout;
// We are in the wakeup list! So we have to act and we know our
// tail has not expired (else it would have removed us from the list).
// Remove ourselves (and any prior Wakeup) from the wakeup list.
wakeup = wakeup._next;
Timeout new_timeout;
if (timeout._at <= now)
{
// We have timed out!
@ -274,7 +285,11 @@ public abstract class CyclicTimeout implements Destroyable
@Override
public String toString()
{
return String.format("%s@%x:%d->%s", getClass().getSimpleName(), hashCode(), _at, _next);
return String.format("%s@%x:%dms->%s",
getClass().getSimpleName(),
hashCode(),
_at == MAX_VALUE ? _at : TimeUnit.NANOSECONDS.toMillis(_at - System.nanoTime()),
_next);
}
}
}