com.signalfx.shaded.jetty.websocket.common.io.ConnectionState Maven / Gradle / Ivy
//
// ========================================================================
// Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package com.signalfx.shaded.jetty.websocket.common.io;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
/**
* WebSocket Connection State.
*
* {@code State} can only go in one direction from {@code HANDSHAKING} to {@code DISCONNECTED}.
*
*/
public class ConnectionState
{
private final AtomicReference state = new AtomicReference<>(State.HANDSHAKING);
private final AtomicBoolean wasOpened = new AtomicBoolean(false);
/**
* Test to see if state allows writing of WebSocket frames
*
* @return true if state allows for writing of websocket frames
*/
public boolean canWriteWebSocketFrames()
{
State current = state.get();
return current == State.OPENING || current == State.OPENED;
}
/**
* Tests to see if state allows for reading of WebSocket frames
*
* @return true if state allows for reading of websocket frames
*/
public boolean canReadWebSocketFrames()
{
State current = state.get();
return current == State.OPENED || current == State.CLOSING;
}
/**
* Tests to see if state got past the initial HANDSHAKING state
*
* @return true if the connection state was opened
*/
public boolean wasOpened()
{
return wasOpened.get();
}
/**
* Requests that the connection migrate to OPENING state
*
* @return true if OPENING state attained
*/
public boolean opening()
{
while (true)
{
State current = state.get();
switch (current)
{
case HANDSHAKING:
if (state.compareAndSet(current, State.OPENING))
{
wasOpened.set(true);
return true;
}
break;
case CLOSING: // Connection closed from WebSocketSession doStop before connection was opened)
return false;
case DISCONNECTED:
return false;
default:
throw new IllegalStateException(toString(current));
}
}
}
/**
* Requests that the connection migrate to OPENED state
*
* @return true if OPENED state attained
*/
public boolean opened()
{
while (true)
{
State current = state.get();
switch (current)
{
case OPENING:
if (state.compareAndSet(current, State.OPENED))
{
return true;
}
break;
case CLOSING: // connection went from OPENING to CLOSING (likely to to failure to onOpen)
return false;
case DISCONNECTED:
return false;
default:
throw new IllegalStateException(toString(current));
}
}
}
/**
* The Local Endpoint wants to close.
*
* @return true if this is the first local close
*/
public boolean closing()
{
while (true)
{
State current = state.get();
switch (current)
{
case HANDSHAKING:
case OPENING:
case OPENED:
if (state.compareAndSet(current, State.CLOSING))
{
return true;
}
break;
case CLOSING: // already closing
return false;
case DISCONNECTED:
return false;
default:
throw new IllegalStateException(toString(current));
}
}
}
/**
* Final Terminal state indicating the connection is disconnected
*
* @return true if disconnected reached for the first time
*/
public boolean disconnected()
{
while (true)
{
State current = state.get();
switch (current)
{
case DISCONNECTED:
return false;
default:
if (state.compareAndSet(current, State.DISCONNECTED))
{
return true;
}
break;
}
}
}
private String toString(State state)
{
return String.format("%s@%x[%s]", getClass().getSimpleName(), hashCode(), state);
}
@Override
public String toString()
{
return toString(state.get());
}
private enum State
{
/**
* Initial state of a connection, the upgrade request / response handshake is in progress
*/
HANDSHAKING,
/**
* Intermediate state between HANDSHAKING and OPENED, used to indicate that a upgrade
* request/response handshake is successful, but the Application provided socket's
* onOpen code has yet completed.
*
* This state is to allow the local socket endpoint to initiate the sending of messages and
* frames, but to NOT start reading yet.
*/
OPENING,
/**
* The websocket connection is established and open.
*
* This indicates that the Upgrade has succeed, and the Application provided
* socket's onOpen code has returned.
*
* It is now time to start reading from the remote endpoint.
*/
OPENED,
/**
* The WebSocket is closing
*
* There are several conditions that would start this state.
*
* - A CLOSE Frame has been received (and parsed) from the remote endpoint
* - A CLOSE Frame has been enqueued by the local endpoint
*/
CLOSING,
/**
* The WebSocket connection is disconnected.
*
* Connection is complete and no longer valid.
*/
DISCONNECTED
}
}