[icedtea-web] RFC: move TimedHashMap to netx
Dr Andrew John Hughes
ahughes at redhat.com
Mon Feb 14 14:42:46 PST 2011
On 16:33 Mon 14 Feb , Omair Majid wrote:
> Hi,
>
> The attached patch moves TimeHashMap from
> plugin/icedteanp/java/sun/applet/PluginProxySelector.java to
> netx/net/sourceforge/jnlp/util/TimedHashMap.java, so other
> ProxySelectors can also use it. My patch for adding proxy auto config
> support will be using this new class.
>
> Other than the movement, there are a few minor changes to it:
> - It no longer extends HashMap. TimedHashMap did not override all the
> HashMap methods and it was possible to see inconsistent data. By
> reducing the interface, this should not be a problem any more (the
> plugin code still compiles fine).
> - The use of Date has been replaced by System.nanoTime(). This should
> give us a more monotonic clock and be less susceptible to clock
> changes (especially to moving the clock backwards).
>
> Any thoughts or concerns?
>
Could you do the move in a separate patch to the other changes?
Otherwise, the changes are unclear as the file appears new.
> ChangeLog:
>
> 2011-02-14 Omair Majid <omajid at redhat.com>
>
> * plugin/icedteanp/java/sun/applet/PluginProxySelector.java:
> Move TimedHashMap to its own class.
> * netx/net/sourceforge/jnlp/util/TimedHashMap.java: New class.
> Moved from sun.applet.PluginProxySelector. Do not subclass HashMap.
> Use System.nanoTime() instead of Date.getTime().
>
> Cheers,
> Omair
> diff -r c6f717dfcb97 netx/net/sourceforge/jnlp/util/TimedHashMap.java
> --- /dev/null Thu Jan 01 00:00:00 1970 +0000
> +++ b/netx/net/sourceforge/jnlp/util/TimedHashMap.java Mon Feb 14 16:04:28 2011 -0500
> @@ -0,0 +1,100 @@
> +/* TimedHashMap.java
> + Copyright (C) 2011 Red Hat, Inc.
> +
> +This file is part of IcedTea.
> +
> +IcedTea is free software; you can redistribute it and/or modify
> +it under the terms of the GNU General Public License as published by
> +the Free Software Foundation; either version 2, or (at your option)
> +any later version.
> +
> +IcedTea 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 for more details.
> +
> +You should have received a copy of the GNU General Public License
> +along with IcedTea; see the file COPYING. If not, write to the
> +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
> +02110-1301 USA.
> +
> +Linking this library statically or dynamically with other modules is
> +making a combined work based on this library. Thus, the terms and
> +conditions of the GNU General Public License cover the whole
> +combination.
> +
> +As a special exception, the copyright holders of this library give you
> +permission to link this library with independent modules to produce an
> +executable, regardless of the license terms of these independent
> +modules, and to copy and distribute the resulting executable under
> +terms of your choice, provided that you also meet, for each linked
> +independent module, the terms and conditions of the license of that
> +module. An independent module is a module which is not derived from
> +or based on this library. If you modify this library, you may extend
> +this exception to your version of the library, but you are not
> +obligated to do so. If you do not wish to do so, delete this
> +exception statement from your version. */
> +
> +package net.sourceforge.jnlp.util;
> +
> +import java.util.HashMap;
> +
> +import net.sourceforge.jnlp.runtime.JNLPRuntime;
> +
> +/**
> + * Simple utility class that extends HashMap by adding an expiry to the entries.
> + *
> + * This map stores entries, and returns them only if the entries were last accessed within time t=10 seconds
> + *
> + * @param K The key type
> + * @param V The Object type
> + */
> +public class TimedHashMap<K, V> {
> +
> + HashMap<K,V> actualMap = new HashMap<K,V>();
> + HashMap<K, Long> timeStamps = new HashMap<K, Long>();
> + Long expiry = 10000000000L;
> +
> + /**
> + * Store the item in the map and associate a timestamp with it
> + *
> + * @param key The key
> + * @param value The value to store
> + */
> + public V put(K key, V value) {
> + timeStamps.put(key, System.nanoTime());
> + return actualMap.put(key, value);
> + }
> +
> + /**
> + * Return cached item if it has not already expired.
> + *
> + * Before returning, this method also resets the "last accessed"
> + * time for this entry, so it is good for another 10 seconds
> + *
> + * @param key The key
> + */
> + public V get(K key) {
> + Long now = System.nanoTime();
> +
> + if (actualMap.containsKey(key)) {
> + Long age = now - timeStamps.get(key);
> +
> + // Item exists. If it has not expired, renew its access time and return it
> + if (age <= expiry) {
> + if (JNLPRuntime.isDebug()) {
> + System.err.println("Returning proxy " + actualMap.get(key) + " from cache for " + key);
> + }
> + timeStamps.put(key, System.nanoTime());
> + return actualMap.get(key);
> + } else {
> + if (JNLPRuntime.isDebug()) {
> + System.err.println("Proxy cache for " + key + " has expired (age=" + (age * 1e-9) + " seconds)");
> + }
> + }
> + }
> +
> + return null;
> + }
> +}
> +
> diff -r c6f717dfcb97 plugin/icedteanp/java/sun/applet/PluginProxySelector.java
> --- a/plugin/icedteanp/java/sun/applet/PluginProxySelector.java Fri Feb 11 20:13:11 2011 -0500
> +++ b/plugin/icedteanp/java/sun/applet/PluginProxySelector.java Mon Feb 14 16:04:28 2011 -0500
> @@ -40,12 +40,11 @@
> import java.net.InetSocketAddress;
> import java.net.Proxy;
> import java.net.URI;
> -import java.util.Date;
> import java.util.ArrayList;
> -import java.util.HashMap;
> import java.util.List;
>
> import net.sourceforge.jnlp.runtime.JNLPProxySelector;
> +import net.sourceforge.jnlp.util.TimedHashMap;
>
> /**
> * Proxy selector implementation for plugin network functions.
> @@ -129,59 +128,6 @@
> return null;
> }
>
> - /**
> - * Simple utility class that extends HashMap by adding an expiry to the entries.
> - *
> - * This map stores entries, and returns them only if the entries were last accessed within time t=10 seconds
> - *
> - * @param <K> The key type
> - * @param <V> The Object type
> - */
>
> - private class TimedHashMap<K, V> extends HashMap<K, V> {
> -
> - HashMap<K, Long> timeStamps = new HashMap<K, Long>();
> - Long expiry = 10000L;
> -
> - /**
> - * Store the item in the map and associate a timestamp with it
> - *
> - * @param key The key
> - * @param value The value to store
> - */
> - public V put(K key, V value) {
> - timeStamps.put(key, new Date().getTime());
> - return super.put(key, value);
> - }
> -
> - /**
> - * Return cached item if it has not already expired.
> - *
> - * Before returning, this method also resets the "last accessed"
> - * time for this entry, so it is good for another 10 seconds
> - *
> - * @param key The key
> - */
> - @SuppressWarnings("unchecked")
> - public V get(Object key) {
> -
> - Long now = new Date().getTime();
> -
> - if (super.containsKey(key)) {
> - Long age = now - timeStamps.get(key);
> -
> - // Item exists. If it has not expired, renew its access time and return it
> - if (age <= expiry) {
> - PluginDebug.debug("Returning proxy " + super.get(key) + " from cache for " + key);
> - timeStamps.put((K) key, (new Date()).getTime());
> - return super.get(key);
> - } else {
> - PluginDebug.debug("Proxy cache for " + key + " has expired (age=" + age / 1000.0 + " seconds)");
> - }
> - }
> -
> - return null;
> - }
> - }
>
> }
--
Andrew :)
Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)
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