/*
* Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This source code is provided to illustrate the usage of a given feature
* or technique and has been deliberately simplified. Additional steps
* required for a production-quality application, such as security checks,
* input validation and proper error handling, might not be present in
* this sample code.
*/
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.util.LinkedList;
import java.util.Queue;
import java.util.concurrent.atomic.AtomicReference;
/**
* Client represents a remote connection to the chat server.
* It contains methods for reading and writing messages from the
* channel.
* Messages are considered to be separated by newline, so incomplete
* messages are buffered in the {@code Client}.
*
* All reads and writes are asynchronous and uses the nio2 asynchronous
* elements.
*/
class Client {
private final AsynchronousSocketChannel channel;
private AtomicReference<ClientReader> reader;
private String userName;
private final StringBuilder messageBuffer = new StringBuilder();
private final Queue<ByteBuffer> queue = new LinkedList<ByteBuffer>();
private boolean writing = false;
public Client(AsynchronousSocketChannel channel, ClientReader reader) {
this.channel = channel;
this.reader = new AtomicReference<ClientReader>(reader);
}
/**
* Enqueues a write of the buffer to the channel.
* The call is asynchronous so the buffer is not safe to modify after
* passing the buffer here.
*
* @param buffer the buffer to send to the channel
*/
private void writeMessage(final ByteBuffer buffer) {
boolean threadShouldWrite = false;
synchronized(queue) {
queue.add(buffer);
// Currently no thread writing, make this thread dispatch a write
if (!writing) {
writing = true;
threadShouldWrite = true;
}
}
if (threadShouldWrite) {
writeFromQueue();
}
}
private void writeFromQueue() {
ByteBuffer buffer;
synchronized (queue) {
buffer = queue.poll();
if (buffer == null) {
writing = false;
}
}
// No new data in buffer to write
if (writing) {
writeBuffer(buffer);
}
}
private void writeBuffer(ByteBuffer buffer) {
channel.write(buffer, buffer, new CompletionHandler<Integer, ByteBuffer>() {
@Override
public void completed(Integer result, ByteBuffer buffer) {
if (buffer.hasRemaining()) {
channel.write(buffer, buffer, this);
} else {
// Go back and check if there is new data to write
writeFromQueue();
}
}
@Override
public void failed(Throwable exc, ByteBuffer attachment) {
}
});
}
/**
* Sends a message
* @param string the message
*/
public void writeStringMessage(String string) {
writeMessage(ByteBuffer.wrap(string.getBytes()));
}
/**
* Send a message from a specific client
* @param client the message is sent from
* @param message to send
*/
public void writeMessageFrom(Client client, String message) {
if (reader.get().acceptsMessages()) {
writeStringMessage(client.getUserName() + ": " + message);
}
}
/**
* Enqueue a read
* @param completionHandler callback on completed read
*/
public void read(CompletionHandler<Integer, ? super ByteBuffer> completionHandler) {
ByteBuffer input = ByteBuffer.allocate(256);
if (!channel.isOpen()) {
return;
}
channel.read(input, input, completionHandler);
}
/**
* Closes the channel
*/
public void close() {
try {
channel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* Run the current states actions.
*/
public void run() {
reader.get().run(this);
}
public void setUserName(String userName) {
this.userName = userName;
}
public void setReader(ClientReader reader) {
this.reader.set(reader);
}
public String getUserName() {
return userName;
}
public void appendMessage(String message) {
synchronized (messageBuffer) {
messageBuffer.append(message);
}
}
/**
* @return the next newline separated message in the buffer. null is returned if the buffer
* doesn't contain any newline.
*/
public String nextMessage() {
synchronized(messageBuffer) {
int nextNewline = messageBuffer.indexOf("\n");
if (nextNewline == -1) {
return null;
}
String message = messageBuffer.substring(0, nextNewline + 1);
messageBuffer.delete(0, nextNewline + 1);
return message;
}
}
}