jetty-9 factored out IdleTimeout

jetty-io/src/main/java/org/eclipse/jetty/io/IdleTimeout.java

@@ -0,0 +1,135 @@
+package org.eclipse.jetty.io;
+
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.eclipse.jetty.util.log.Log;
+import org.eclipse.jetty.util.log.Logger;
+import org.eclipse.jetty.util.thread.Scheduler;
+
+
+
+/* ------------------------------------------------------------ */
+/** An Abstract implementation of an Idle Timeout.
+ * 
+ * This implementation is optimised that timeout operations are not cancelled on
+ * every operation. Rather timeout are allowed to expire and a check is then made 
+ * to see when the last operation took place.  If the idle timeout has not expired, 
+ * the timeout is rescheduled for the earliest possible time a timeout could occur.
+ * 
+ */
+public abstract class IdleTimeout
+{
+    private static final Logger LOG = Log.getLogger(IdleTimeout.class);
+    private final Scheduler _scheduler;
+    private final AtomicReference<Scheduler.Task> _timeout = new AtomicReference<>();
+    private volatile long _idleTimeout;
+    private volatile long _idleTimestamp=System.currentTimeMillis();
+    
+    private final Runnable _idleTask = new Runnable()
+    {
+        @Override
+        public void run()
+        {
+            long idleLeft=checkIdleTimeout();
+            if (idleLeft>=0)
+                scheduleIdleTimeout(idleLeft > 0 ? idleLeft : getIdleTimeout());
+        }
+    };
+
+    /* ------------------------------------------------------------ */
+    /**
+     * @param scheduler A scheduler used to schedule checks for the idle timeout.
+     */
+    public IdleTimeout(Scheduler scheduler)
+    {
+        _scheduler=scheduler;
+    }
+    
+    public long getIdleTimestamp()
+    {
+        return _idleTimestamp;
+    }
+    
+    public long getIdleTimeout()
+    {
+        return _idleTimeout;
+    }
+
+    public void setIdleTimeout(long idleTimeout)
+    {
+        _idleTimeout = idleTimeout;
+    }
+
+    /* ------------------------------------------------------------ */
+    /** This method should be called when non-idle activity has taken place.
+     */
+    public void notIdle()
+    {
+        _idleTimestamp=System.currentTimeMillis();
+    }
+    
+    protected void scheduleIdleTimeout(long delay)
+    {
+        Scheduler.Task newTimeout = null;
+        if (isOpen() && delay > 0 && _scheduler!=null)
+            newTimeout = _scheduler.schedule(_idleTask, delay, TimeUnit.MILLISECONDS);
+        Scheduler.Task oldTimeout = _timeout.getAndSet(newTimeout);
+        if (oldTimeout != null)
+            oldTimeout.cancel();
+    }
+    
+    protected void close()
+    {
+        Scheduler.Task oldTimeout = _timeout.getAndSet(null);
+        if (oldTimeout != null)
+            oldTimeout.cancel();
+    }
+    
+    protected long checkIdleTimeout()
+    {
+        if (isOpen())
+        {
+            long idleTimestamp = getIdleTimestamp();
+            long idleTimeout = getIdleTimeout();
+            long idleElapsed = System.currentTimeMillis() - idleTimestamp;
+            long idleLeft = idleTimeout - idleElapsed;
+
+            LOG.debug("{} idle timeout check, elapsed: {} ms, remaining: {} ms", this, idleElapsed, idleLeft);
+
+            if (idleTimestamp != 0 && idleTimeout > 0)
+            {
+                if (idleLeft <= 0)
+                {
+                    LOG.debug("{} idle timeout expired", this);
+                    try
+                    {
+                        onIdleExpired(new TimeoutException("Idle timeout expired: " + idleElapsed + "/" + idleTimeout + " ms"));
+                    }
+                    finally
+                    {
+                        notIdle();
+                    }
+                }
+            }
+
+            return idleLeft>=0?idleLeft:0;
+        }
+        return -1;
+    }
+    
+    /* ------------------------------------------------------------ */
+    /** This abstract method is called when the idle timeout has expired.
+     * @param timeout a TimeoutException
+     */
+    abstract protected void onIdleExpired(TimeoutException timeout);
+    
+    
+    /* ------------------------------------------------------------ */
+    /** This abstract method should be called to check if idle timeouts
+     * should still be checked.
+     * @return True if the entity monitored should still be checked for idle timeouts
+     */
+    abstract protected boolean isOpen();
+}