Importing upstream Jetty jetty-9.2.1.v20140609

[gigi.git] / lib / jetty / org / eclipse / jetty / io / FillInterest.java

diff --git a/lib/jetty/org/eclipse/jetty/io/FillInterest.java b/lib/jetty/org/eclipse/jetty/io/FillInterest.java
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+//
+//  ========================================================================
+//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.io;
+
+import java.io.IOException;
+import java.nio.channels.ClosedChannelException;
+import java.nio.channels.ReadPendingException;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.eclipse.jetty.util.Callback;
+import org.eclipse.jetty.util.log.Log;
+import org.eclipse.jetty.util.log.Logger;
+
+
+/* ------------------------------------------------------------ */
+/** 
+ * A Utility class to help implement {@link EndPoint#fillInterested(Callback)}
+ * by keeping state and calling the context and callback objects.
+ * 
+ */
+public abstract class FillInterest
+{
+    private final static Logger LOG = Log.getLogger(FillInterest.class);
+    private final AtomicReference<Callback> _interested = new AtomicReference<>(null);
+
+    /* ------------------------------------------------------------ */
+    protected FillInterest()
+    {
+    }
+
+    /* ------------------------------------------------------------ */
+    /** Call to register interest in a callback when a read is possible.
+     * The callback will be called either immediately if {@link #needsFill()} 
+     * returns true or eventually once {@link #fillable()} is called.
+     * @param callback
+     * @throws ReadPendingException
+     */
+    public <C> void register(Callback callback) throws ReadPendingException
+    {
+        if (callback==null)
+            throw new IllegalArgumentException();
+        
+        if (!_interested.compareAndSet(null,callback))
+        {
+            LOG.warn("Read pending for "+_interested.get()+" pervented "+callback);
+            throw new ReadPendingException();
+        }
+        try
+        {
+            if (needsFill())
+                fillable();
+        }
+        catch(IOException e)
+        {
+            onFail(e);
+        }
+    }
+
+    /* ------------------------------------------------------------ */
+    /** Call to signal that a read is now possible.
+     */
+    public void fillable()
+    {
+        Callback callback=_interested.get();
+        if (callback!=null && _interested.compareAndSet(callback,null))
+            callback.succeeded();
+    }
+
+    /* ------------------------------------------------------------ */
+    /**
+     * @return True if a read callback has been registered
+     */
+    public boolean isInterested()
+    {
+        return _interested.get()!=null;
+    }
+    
+    /* ------------------------------------------------------------ */
+    /** Call to signal a failure to a registered interest
+     * @return true if the cause was passed to a {@link Callback} instance
+     */
+    public boolean onFail(Throwable cause)
+    {
+        Callback callback=_interested.get();
+        if (callback!=null && _interested.compareAndSet(callback,null))
+        {
+            callback.failed(cause);
+            return true;
+        }
+        return false;
+    }
+    
+    /* ------------------------------------------------------------ */
+    public void onClose()
+    {
+        Callback callback=_interested.get();
+        if (callback!=null && _interested.compareAndSet(callback,null))
+            callback.failed(new ClosedChannelException());
+    }
+    
+    /* ------------------------------------------------------------ */
+    @Override
+    public String toString()
+    {
+        return String.format("FillInterest@%x{%b,%s}",hashCode(),_interested.get(),_interested.get());
+    }
+    
+    /* ------------------------------------------------------------ */
+    /** Register the read interest 
+     * Abstract method to be implemented by the Specific ReadInterest to
+     * enquire if a read is immediately possible and if not to schedule a future
+     * call to {@link #fillable()} or {@link #onFail(Throwable)}
+     * @return true if a read is possible
+     * @throws IOException
+     */
+    abstract protected boolean needsFill() throws IOException;
+    
+    
+}