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