/**
* Copyright (c) 2009, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.wso2.carbon.transport.relay.connections;
import org.apache.http.nio.NHttpClientConnection;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.protocol.ExecutionContext;
import org.apache.http.protocol.HttpContext;
import java.util.List;
import java.util.ArrayList;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* This stores connections for a particular host + port.
*/
public class HostConnections {
private static final Log log = LogFactory.getLog(HostConnections.class);
// host
private String host;
// port
private int port;
// maximum number of connections allowed for this host + port
private int maxSize;
// number of awaiting connections
private int pendingConnections;
// list of free connections available
private List<NHttpClientConnection> freeConnections = new ArrayList<NHttpClientConnection>();
// list of connections in use
private List<NHttpClientConnection> busyConnections = new ArrayList<NHttpClientConnection>();
private Lock lock = new ReentrantLock();
public HostConnections(String host, int port, int maxSize) {
if (log.isDebugEnabled()) {
log.debug("Creating new connection pool to the host: " + host + ", port: " + port);
}
this.host = host;
this.port = port;
this.maxSize = maxSize;
}
/**
* Get a connection for the host:port
*
* @return a connection
*/
public NHttpClientConnection getConnection() {
lock.lock();
try {
if (freeConnections.size() > 0) {
if (log.isDebugEnabled()) {
log.debug("Returning an existing free connection to " + host + ":" + port);
}
NHttpClientConnection conn = freeConnections.get(0);
freeConnections.remove(conn);
busyConnections.add(conn);
return conn;
}
} finally {
lock.unlock();
}
return null;
}
public void release(NHttpClientConnection conn) {
conn.getMetrics().reset();
HttpContext ctx = conn.getContext();
ctx.removeAttribute(ExecutionContext.HTTP_REQUEST);
ctx.removeAttribute(ExecutionContext.HTTP_RESPONSE);
lock.lock();
try {
if (busyConnections.remove(conn)) {
freeConnections.add(conn);
} else {
log.error("Attempted to releaseConnection connection not in the busy list");
}
} finally {
lock.unlock();
}
}
public void forget(NHttpClientConnection conn) {
lock.lock();
try {
if (!freeConnections.remove(conn)) {
busyConnections.remove(conn);
}
} finally {
lock.unlock();
}
}
public void addConnection(NHttpClientConnection conn) {
if (log.isDebugEnabled()) {
log.debug("New connection to " + host + ":" + port + " is added to the free list");
}
lock.lock();
try {
freeConnections.add(conn);
} finally {
lock.unlock();
}
}
/**
* Indicates that a connection has been successfully established with a remote server
* as notified by the session request call back.
*/
public synchronized void pendingConnectionSucceeded() {
lock.lock();
try {
pendingConnections--;
} finally {
lock.unlock();
}
}
/**
* Keep track of the number of times connections to this host:port has failed
* consecutively
*/
public void pendingConnectionFailed() {
lock.lock();
try {
pendingConnections--;
} finally {
lock.unlock();
}
}
public String getHost() {
return host;
}
public int getPort() {
return port;
}
public boolean canHaveMoreConnections() {
return busyConnections.size() + pendingConnections < maxSize;
}
}