--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/sun/net/httpserver/SelectorCache.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,134 @@
+/*
+ * Copyright 2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package sun.net.httpserver;
+
+import java.util.*;
+import java.nio.*;
+import java.net.*;
+import java.io.*;
+import java.security.*;
+import java.nio.channels.*;
+
+/*
+ * Implements a cache of java.nio.channels.Selector
+ * where Selectors are allocated on demand and placed
+ * in a temporary cache for a period of time, so they
+ * can be reused. If a period of between 2 and 4 minutes
+ * elapses without being used, then they are closed.
+ */
+public class SelectorCache {
+
+    static SelectorCache cache = null;
+
+    private SelectorCache () {
+        freeSelectors = new LinkedList<SelectorWrapper>();
+        CacheCleaner c = AccessController.doPrivileged(
+            new PrivilegedAction<CacheCleaner>() {
+            public CacheCleaner run() {
+                CacheCleaner cleaner = new CacheCleaner();
+                cleaner.setDaemon (true);
+                return cleaner;
+            }
+        });
+        c.start();
+    }
+
+    /**
+     * factory method for creating single instance
+     */
+    public static SelectorCache getSelectorCache () {
+        synchronized (SelectorCache.class) {
+            if (cache == null) {
+                cache = new SelectorCache ();
+            }
+        }
+        return cache;
+    }
+
+    private static class SelectorWrapper {
+        private Selector sel;
+        private boolean deleteFlag;
+        private SelectorWrapper (Selector sel) {
+            this.sel = sel;
+            this.deleteFlag = false;
+        }
+        public Selector getSelector() { return sel;}
+        public boolean getDeleteFlag () {return deleteFlag;}
+        public void setDeleteFlag (boolean b) {deleteFlag = b;}
+    }
+
+    /* list of free selectors. Can be re-allocated for a period
+     * of time, after which if not allocated will be closed
+     * and removed from the list (by CacheCleaner thread)
+     */
+    LinkedList<SelectorWrapper> freeSelectors;
+
+    synchronized Selector getSelector () throws IOException {
+        SelectorWrapper wrapper = null;
+        Selector selector;
+
+        if (freeSelectors.size() > 0) {
+            wrapper = freeSelectors.remove();
+            selector = wrapper.getSelector();
+        } else {
+            selector = Selector.open();
+        }
+        return selector;
+    }
+
+    synchronized void freeSelector (Selector selector) {
+        freeSelectors.add (new SelectorWrapper (selector));
+    }
+
+    /* Thread ensures that entries on freeSelector list
+     * remain there for at least 2 minutes and no longer
+     * than 4 minutes.
+     */
+    class CacheCleaner extends Thread {
+        public void run () {
+            long timeout = ServerConfig.getSelCacheTimeout() * 1000;
+            while (true) {
+                try {Thread.sleep (timeout); } catch (Exception e) {}
+                synchronized (freeSelectors) {
+                    ListIterator<SelectorWrapper> l = freeSelectors.listIterator();
+                    while (l.hasNext()) {
+                        SelectorWrapper w = l.next();
+                        if (w.getDeleteFlag()) {
+                            /* 2nd pass. Close the selector */
+                            try {
+                                w.getSelector().close();
+                            } catch (IOException e) {}
+                            l.remove();
+                        } else {
+                            /* 1st pass. Set the flag */
+                            w.setDeleteFlag (true);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}