/*
* Copyright (c) 2006, Oracle and/or its affiliates. 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.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);
}
}
}
}
}
}
}