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/*
* JBoss, Home of Professional Open Source.
* Copyright 2017 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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.jboss.ejb.client;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Map;
import org.wildfly.common.Assert;
/**
* An object which may have attachments. Even if the object is serializable, its
* attachment map is not and will always deserialize empty.
*
* @author David M. Lloyd
*/
public abstract class Attachable {
private final Map, Object> attachments;
private Attachable(Map, Object> attachments) {
this.attachments = attachments;
}
Attachable() {
this(new IdentityHashMap, Object>());
}
/**
* Construct a new instance, sharing attachments with another instance.
*
* @param attachable the attachments to share
*/
Attachable(final Attachable attachable) {
this(attachable.attachments);
}
/**
* Get an attachment from this object.
*
* @param key the attachment key
* @param the attachment type
* @return the attachment value
*/
@SuppressWarnings("unchecked")
public T getAttachment(AttachmentKey key) {
if (key == null) return null;
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) attachments.get(key);
}
}
/**
* Returns the attachments applicable for this {@link Attachable}. The returned {@link Map}
* is an unmodifiable {@link Map}. If there are no attachments for this {@link Attachable}
* then this method returns an empty {@link Map}
*
* @return a read-only copy of the attachments map
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public Map, ?> getAttachments() {
if (this.attachments == null) {
return Collections.emptyMap();
}
return Collections.unmodifiableMap((Map) this.attachments);
}
/**
* Set an attachment on this object.
*
* @param key the attachment key
* @param value the attachment's new value (may not be {@code null})
* @param the attachment type
* @return the previous attachment value, or {@code null} if there was none
*/
@SuppressWarnings("unchecked")
public T putAttachment(AttachmentKey key, T value) {
Assert.checkNotNullParam("key", key);
Assert.checkNotNullParam("value", value);
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) attachments.put(key, value);
}
}
/**
* Set an attachment on this object if an existing attachment does not already exist.
*
* @param key the attachment key
* @param value the attachment's new value (may not be {@code null})
* @param the attachment type
* @return the previous attachment value, or {@code null} if there was none
*/
@SuppressWarnings("unchecked")
public T putAttachmentIfAbsent(AttachmentKey key, T value) {
Assert.checkNotNullParam("key", key);
Assert.checkNotNullParam("value", value);
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) (attachments.containsKey(key) ? attachments.get(key) : attachments.put(key, value));
}
}
/**
* Replace an attachment on this object if an existing attachment exists.
*
* @param key the attachment key
* @param value the attachment's new value (may not be {@code null})
* @param the attachment type
* @return the previous attachment value, or {@code null} if there was none
*/
@SuppressWarnings("unchecked")
public T replaceAttachment(AttachmentKey key, T value) {
if (key == null) return null;
Assert.checkNotNullParam("value", value);
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) (attachments.containsKey(key) ? attachments.put(key, value) : null);
}
}
/**
* Replace an attachment on this object if an existing attachment exists with a certain value.
*
* @param key the attachment key
* @param oldValue the attachment's expected value (may not be {@code null})
* @param newValue the attachment's new value (may not be {@code null})
* @param the attachment type
* @return {@code true} if the old value matched and the value was replaced; {@code false} otherwise
*/
@SuppressWarnings("unchecked")
public boolean replaceAttachment(AttachmentKey key, T oldValue, T newValue) {
if (key == null) return false;
if (oldValue == null) return false;
Assert.checkNotNullParam("newValue", newValue);
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
Object lhs = attachments.get(key);
return attachments.containsKey(key) && oldValue.equals(lhs) && attachments.put(key, newValue) != null;
}
}
/**
* Remove and return an attachment value.
*
* @param key the attachment key
* @param the attachment type
* @return the previous value of the attachment, or {@code null} if there was none
*/
@SuppressWarnings("unchecked")
public T removeAttachment(AttachmentKey key) {
if (key == null) return null;
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
return (T) attachments.remove(key);
}
}
/**
* Remove an attachment if it has a certain value.
*
* @param key the attachment key
* @param value the attachment's expected value (may not be {@code null})
* @param the attachment type
* @return {@code true} if the value was removed, {@code false} if there was no attachment
*/
@SuppressWarnings("unchecked")
public boolean removeAttachment(AttachmentKey key, T value) {
if (key == null) return false;
if (value == null) return false;
final Map, Object> attachments = this.attachments;
synchronized (attachments) {
Object lhs = attachments.get(key);
return attachments.containsKey(key) && value.equals(lhs) && attachments.remove(key) != null;
}
}
void clearAttachments() {
attachments.clear();
}
}
