/*
* Copyright (c) 1996, 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
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*/
package sun.net.www.http;
import java.io.InputStream;
import java.io.IOException;
import java.io.NotSerializableException;
import java.util.*;
import java.net.URL;
import java.util.concurrent.ConcurrentHashMap;
/**
* A class that implements a cache of idle Http connections for keep-alive
*
* @author Stephen R. Pietrowicz (NCSA)
* @author Dave Brown
*/
public class KeepAliveCache extends ConcurrentHashMap implements Runnable {
private static final long serialVersionUID = -2937172892064557949L;
/* maximum # keep-alive connections to maintain at once
* This should be 2 by the HTTP spec, but because we don't support pipe-lining
* a larger value is more appropriate. So we now set a default of 5, and the value
* refers to the number of idle connections per destination (in the cache) only.
* It can be reset by setting system property "http.maxConnections".
*/
static final int MAX_CONNECTIONS = 5;
static int result = -1;
static int getMaxConnections() {
if (result == -1) {
result = java.security.AccessController.doPrivileged(
new sun.security.action.GetIntegerAction("http.maxConnections",
MAX_CONNECTIONS))
.intValue();
if (result <= 0)
result = MAX_CONNECTIONS;
}
return result;
}
static final int LIFETIME = 5000;
private Thread keepAliveTimer = null;
/**
* Constructor
*/
public KeepAliveCache() {}
/**
* Register this URL and HttpClient (that supports keep-alive) with the cache
* @param url The URL contains info about the host and port
* @param http The HttpClient to be cached
*/
public synchronized void put(final URL url, Object obj, HttpClient http) {
boolean startThread = (keepAliveTimer == null);
if (!startThread) {
if (!keepAliveTimer.isAlive()) {
startThread = true;
}
}
if (startThread) {
clear();
/* Unfortunately, we can't always believe the keep-alive timeout we got
* back from the server. If I'm connected through a Netscape proxy
* to a server that sent me a keep-alive
* time of 15 sec, the proxy unilaterally terminates my connection
* The robustness to to get around this is in HttpClient.parseHTTP()
*/
final KeepAliveCache cache = this;
java.security.AccessController.doPrivileged(
new java.security.PrivilegedAction() {
public Object run() {
// We want to create the Keep-Alive-Timer in the
// system threadgroup
ThreadGroup grp = Thread.currentThread().getThreadGroup();
ThreadGroup parent = null;
while ((parent = grp.getParent()) != null) {
grp = parent;
}
keepAliveTimer = new Thread(grp, cache, "Keep-Alive-Timer");
keepAliveTimer.setDaemon(true);
keepAliveTimer.setPriority(Thread.MAX_PRIORITY - 2);
keepAliveTimer.start();
return null;
}
});
}
KeepAliveKey key = new KeepAliveKey(url, obj);
ClientVector v = (ClientVector)super.get(key);
if (v == null) {
int keepAliveTimeout = http.getKeepAliveTimeout();
v = new ClientVector(keepAliveTimeout > 0?
keepAliveTimeout*1000 : LIFETIME);
v.put(http);
super.put(key, v);
} else {
v.put(http);
}
}
/* remove an obsolete HttpClient from it's VectorCache */
public synchronized void remove (HttpClient h, Object obj) {
KeepAliveKey key = new KeepAliveKey(h.url, obj);
ClientVector v = (ClientVector)super.get(key);
if (v != null) {
v.remove(h);
if (v.empty()) {
removeVector(key);
}
}
}
/* called by a clientVector thread when all it's connections have timed out
* and that vector of connections should be removed.
*/
synchronized void removeVector(KeepAliveKey k) {
super.remove(k);
}
/**
* Check to see if this URL has a cached HttpClient
*/
public synchronized Object get(URL url, Object obj) {
KeepAliveKey key = new KeepAliveKey(url, obj);
ClientVector v = (ClientVector)super.get(key);
if (v == null) { // nothing in cache yet
return null;
}
return v.get();
}
/* Sleeps for an alloted timeout, then checks for timed out connections.
* Errs on the side of caution (leave connections idle for a relatively
* short time).
*/
public void run() {
int total_cache;
do {
try {
Thread.sleep(LIFETIME);
} catch (InterruptedException e) {}
synchronized (this) {
/* Remove all unused HttpClients. Starting from the
* bottom of the stack (the least-recently used first).
* REMIND: It'd be nice to not remove *all* connections
* that aren't presently in use. One could have been added
* a second ago that's still perfectly valid, and we're
* needlessly axing it. But it's not clear how to do this
* cleanly, and doing it right may be more trouble than it's
* worth.
*/
long currentTime = System.currentTimeMillis();
Iterator itr = keySet().iterator();
ArrayList keysToRemove = new ArrayList();
while (itr.hasNext()) {
KeepAliveKey key = (KeepAliveKey)itr.next();
ClientVector v = (ClientVector)get(key);
synchronized (v) {
int i;
for (i = 0; i < v.size(); i++) {
KeepAliveEntry e = (KeepAliveEntry)v.elementAt(i);
if ((currentTime - e.idleStartTime) > v.nap) {
HttpClient h = e.hc;
h.closeServer();
} else {
break;
}
}
v.subList(0, i).clear();
if (v.size() == 0) {
keysToRemove.add(key);
}
}
}
itr = keysToRemove.iterator();
while (itr.hasNext()) {
removeVector((KeepAliveKey)itr.next());
}
}
} while (size() > 0);
return;
}
/*
* Do not serialize this class!
*/
private void writeObject(java.io.ObjectOutputStream stream)
throws IOException {
throw new NotSerializableException();
}
private void readObject(java.io.ObjectInputStream stream)
throws IOException, ClassNotFoundException {
throw new NotSerializableException();
}
}
/* FILO order for recycling HttpClients, should run in a thread
* to time them out. If > maxConns are in use, block.
*/
class ClientVector extends java.util.Stack {
private static final long serialVersionUID = -8680532108106489459L;
// sleep time in milliseconds, before cache clear
int nap;
ClientVector (int nap) {
this.nap = nap;
}
synchronized HttpClient get() {
if (empty()) {
return null;
} else {
// Loop until we find a connection that has not timed out
HttpClient hc = null;
long currentTime = System.currentTimeMillis();
do {
KeepAliveEntry e = (KeepAliveEntry)pop();
if ((currentTime - e.idleStartTime) > nap) {
e.hc.closeServer();
} else {
hc = e.hc;
}
} while ((hc== null) && (!empty()));
return hc;
}
}
/* return a still valid, unused HttpClient */
synchronized void put(HttpClient h) {
if (size() > KeepAliveCache.getMaxConnections()) {
h.closeServer(); // otherwise the connection remains in limbo
} else {
push(new KeepAliveEntry(h, System.currentTimeMillis()));
}
}
/*
* Do not serialize this class!
*/
private void writeObject(java.io.ObjectOutputStream stream)
throws IOException {
throw new NotSerializableException();
}
private void readObject(java.io.ObjectInputStream stream)
throws IOException, ClassNotFoundException {
throw new NotSerializableException();
}
}
class KeepAliveKey {
private String protocol = null;
private String host = null;
private int port = 0;
private Object obj = null; // additional key, such as socketfactory
/**
* Constructor
*
* @param url the URL containing the protocol, host and port information
*/
public KeepAliveKey(URL url, Object obj) {
this.protocol = url.getProtocol();
this.host = url.getHost();
this.port = url.getPort();
this.obj = obj;
}
/**
* Determine whether or not two objects of this type are equal
*/
public boolean equals(Object obj) {
if ((obj instanceof KeepAliveKey) == false)
return false;
KeepAliveKey kae = (KeepAliveKey)obj;
return host.equals(kae.host)
&& (port == kae.port)
&& protocol.equals(kae.protocol)
&& this.obj == kae.obj;
}
/**
* The hashCode() for this object is the string hashCode() of
* concatenation of the protocol, host name and port.
*/
public int hashCode() {
String str = protocol+host+port;
return this.obj == null? str.hashCode() :
str.hashCode() + this.obj.hashCode();
}
}
class KeepAliveEntry {
HttpClient hc;
long idleStartTime;
KeepAliveEntry(HttpClient hc, long idleStartTime) {
this.hc = hc;
this.idleStartTime = idleStartTime;
}
}