/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.sshd.common.channel;
import java.io.IOException;
import org.apache.sshd.common.SshException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A Window for a given channel.
* Windows are used to not overflow the client or server when sending datas.
* Both clients and servers have a local and remote window and won't send
* anymore data until the window has been expanded. When the local window
* is
*
* @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
*/
public class Window {
private final static Logger log = LoggerFactory.getLogger(Window.class);
private final AbstractChannel channel;
private final Object lock;
private final String name;
private int size;
private int maxSize;
private int packetSize;
private boolean waiting;
private boolean closed;
public Window(AbstractChannel channel, Object lock, boolean client, boolean local) {
this.channel = channel;
this.lock = lock != null ? lock : this;
this.name = (client ? "client" : "server") + " " + (local ? "local " : "remote") + " window";
}
public int getSize() {
return size;
}
public int getMaxSize() {
return maxSize;
}
public int getPacketSize() {
return packetSize;
}
public void init(int size, int packetSize) {
this.size = size;
this.maxSize = size;
this.packetSize = packetSize;
}
public void expand(int window) {
synchronized (lock) {
size += window;
if (log.isDebugEnabled()) {
log.debug("Increase " + name + " by " + window + " up to " + size);
}
lock.notifyAll();
}
}
public void consume(int len) {
synchronized (lock) {
//assert size > len;
size -= len;
if (log.isTraceEnabled()) {
log.trace("Consume " + name + " by " + len + " down to " + size);
}
}
}
public void consumeAndCheck(int len) throws IOException {
synchronized (lock) {
//assert size > len;
size -= len;
if (log.isTraceEnabled()) {
log.trace("Consume " + name + " by " + len + " down to " + size);
}
check(maxSize);
}
}
public void check(int maxFree) throws IOException {
int threshold = Math.min(packetSize * 8, maxSize / 4);
synchronized (lock) {
if ((maxFree - size) > packetSize && (maxFree - size > threshold || size < threshold)) {
if (log.isDebugEnabled()) {
log.debug("Increase " + name + " by " + (maxFree - size) + " up to " + maxFree);
}
channel.sendWindowAdjust(maxFree - size);
size = maxFree;
}
}
}
public void waitAndConsume(int len) throws InterruptedException, WindowClosedException {
synchronized (lock) {
while (size < len && !closed) {
log.debug("Waiting for {} bytes on {}", len, name);
waiting = true;
lock.wait();
}
if (waiting) {
log.debug("Space available for {}", name);
waiting = false;
}
if (closed) {
throw new WindowClosedException();
}
size -= len;
if (log.isTraceEnabled()) {
log.trace("Consume " + name + " by " + len + " down to " + size);
}
}
}
public void notifyClosed() {
synchronized (lock) {
closed = true;
if (waiting) {
lock.notifyAll();
}
}
}
}