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filebot/source/net/sourceforge/tuned/Timer.java
2009-10-15 15:18:57 +00:00

91 lines
2.0 KiB
Java

package net.sourceforge.tuned;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
public abstract class Timer implements Runnable {
private final ThreadFactory threadFactory = new DefaultThreadFactory("Timer", Thread.NORM_PRIORITY, true);
private ScheduledThreadPoolExecutor executor;
private ScheduledFuture<?> scheduledFuture;
private Thread shutdownHook;
public synchronized void set(long delay, TimeUnit unit, boolean runBeforeShutdown) {
// create executor if necessary
if (executor == null) {
executor = new ScheduledThreadPoolExecutor(1, threadFactory);
}
// cancel existing future task
if (scheduledFuture != null) {
scheduledFuture.cancel(true);
}
Runnable runnable = this;
if (runBeforeShutdown) {
addShutdownHook();
// remove shutdown hook after execution
runnable = new Runnable() {
@Override
public void run() {
try {
Timer.this.run();
} finally {
cancel();
}
}
};
} else {
// remove existing shutdown hook, if any
removeShutdownHook();
}
scheduledFuture = executor.schedule(runnable, delay, unit);
}
public synchronized void cancel() {
removeShutdownHook();
// stop executor
executor.shutdownNow();
scheduledFuture = null;
executor = null;
}
private synchronized void addShutdownHook() {
if (shutdownHook == null) {
shutdownHook = new Thread(this);
Runtime.getRuntime().addShutdownHook(shutdownHook);
}
}
private synchronized void removeShutdownHook() {
if (shutdownHook != null) {
try {
if (shutdownHook != Thread.currentThread()) {
// can't remove shutdown hooks anymore, once runtime is shutting down,
// so don't remove the shutdown hook, if we are running on the shutdown hook
Runtime.getRuntime().removeShutdownHook(shutdownHook);
}
} finally {
shutdownHook = null;
}
}
}
}