/*
* Copyright 2002-2014 the original author or authors.
*
* 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.springframework.messaging.simp;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* A wrapper class for access to attributes associated with a SiMP session
* (e.g. WebSocket session).
*
* @author Rossen Stoyanchev
* @since 4.1
*/
public class SimpAttributes {
/** Key for the mutex session attribute */
public static final String SESSION_MUTEX_NAME = SimpAttributes.class.getName() + ".MUTEX";
/** Key set after the session is completed */
public static final String SESSION_COMPLETED_NAME = SimpAttributes.class.getName() + ".COMPLETED";
/** Prefix for the name of session attributes used to store destruction callbacks. */
public static final String DESTRUCTION_CALLBACK_NAME_PREFIX = SimpAttributes.class.getName() + ".DESTRUCTION_CALLBACK.";
private static final Log logger = LogFactory.getLog(SimpAttributes.class);
private final String sessionId;
private final Map<String, Object> attributes;
/**
* Constructor wrapping the given session attributes map.
* @param sessionId the id of the associated session
* @param attributes the attributes
*/
public SimpAttributes(String sessionId, Map<String, Object> attributes) {
Assert.notNull(sessionId, "'sessionId' is required");
Assert.notNull(attributes, "'attributes' is required");
this.sessionId = sessionId;
this.attributes = attributes;
}
/**
* Return the value for the attribute of the given name, if any.
* @param name the name of the attribute
* @return the current attribute value, or {@code null} if not found
*/
public Object getAttribute(String name) {
return this.attributes.get(name);
}
/**
* Set the value with the given name replacing an existing value (if any).
* @param name the name of the attribute
* @param value the value for the attribute
*/
public void setAttribute(String name, Object value) {
this.attributes.put(name, value);
}
/**
* Remove the attribute of the given name, if it exists.
* <p>Also removes the registered destruction callback for the specified
* attribute, if any. However it <i>does not</i> execute</i> the callback.
* It is assumed the removed object will continue to be used and destroyed
* independently at the appropriate time.
* @param name the name of the attribute
*/
public void removeAttribute(String name) {
this.attributes.remove(name);
removeDestructionCallback(name);
}
/**
* Retrieve the names of all attributes.
* @return the attribute names as String array, never {@code null}
*/
public String[] getAttributeNames() {
return StringUtils.toStringArray(this.attributes.keySet());
}
/**
* Register a callback to execute on destruction of the specified attribute.
* The callback is executed when the session is closed.
* @param name the name of the attribute to register the callback for
* @param callback the destruction callback to be executed
*/
public void registerDestructionCallback(String name, Runnable callback) {
synchronized (getSessionMutex()) {
if (isSessionCompleted()) {
throw new IllegalStateException("Session id=" + getSessionId() + " already completed");
}
this.attributes.put(DESTRUCTION_CALLBACK_NAME_PREFIX + name, callback);
}
}
private void removeDestructionCallback(String name) {
synchronized (getSessionMutex()) {
this.attributes.remove(DESTRUCTION_CALLBACK_NAME_PREFIX + name);
}
}
/**
* Return an id for the associated session.
* @return the session id as String (never {@code null})
*/
public String getSessionId() {
return this.sessionId;
}
/**
* Expose the object to synchronize on for the underlying session.
* @return the session mutex to use (never {@code null})
*/
public Object getSessionMutex() {
Object mutex = this.attributes.get(SESSION_MUTEX_NAME);
if (mutex == null) {
mutex = this.attributes;
}
return mutex;
}
/**
* Whether the {@link #sessionCompleted()} was already invoked.
*/
public boolean isSessionCompleted() {
return (this.attributes.get(SESSION_COMPLETED_NAME) != null);
}
/**
* Invoked when the session is completed. Executed completion callbacks.
*/
public void sessionCompleted() {
synchronized (getSessionMutex()) {
if (!isSessionCompleted()) {
executeDestructionCallbacks();
this.attributes.put(SESSION_COMPLETED_NAME, Boolean.TRUE);
}
}
}
private void executeDestructionCallbacks() {
for (Map.Entry<String, Object> entry : this.attributes.entrySet()) {
if (entry.getKey().startsWith(DESTRUCTION_CALLBACK_NAME_PREFIX)) {
try {
((Runnable) entry.getValue()).run();
}
catch (Throwable ex) {
logger.error("Uncaught error in session attribute destruction callback", ex);
}
}
}
}
/**
* Extract the SiMP session attributes from the given message and
* wrap them in a {@link SimpAttributes} instance.
* @param message the message to extract session attributes from
*/
public static SimpAttributes fromMessage(Message<?> message) {
Assert.notNull(message, "Message must not be null");
MessageHeaders headers = message.getHeaders();
String sessionId = SimpMessageHeaderAccessor.getSessionId(headers);
Map<String, Object> sessionAttributes = SimpMessageHeaderAccessor.getSessionAttributes(headers);
if (sessionId == null) {
throw new IllegalStateException("No session id in " + message);
}
if (sessionAttributes == null) {
throw new IllegalStateException("No session attributes in " + message);
}
return new SimpAttributes(sessionId, sessionAttributes);
}
}