com.sun.tools.xjc.reader.Ring Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2022 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package com.sun.tools.xjc.reader;
import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;
import com.sun.tools.xjc.ErrorReceiver;
import com.sun.tools.xjc.model.Model;
/**
* Holds all the binding related singleton components in a "ring",
* and let you access those components, creating them as necessary.
*
*
* A {@link Ring} is local to a thread,
* and only one instanceof {@link Ring} can be active at any given time.
*
* Use {@link #begin()} and {@link #end(Ring)} to start/end a ring scope.
* Inside a scope, use {@link #get()} to obtain the instance.
*
*
* When a {@link Model} is built by the reader, an active {@link Ring} scope
* is assumed.
*
*
*
Components in Ring
*
* Depending on the schema language we are dealing with, different
* components are in the model. But at least the following components
* are in the ring.
*
*
* - {@link ErrorReceiver}
*
*
* @author Kohsuke Kawaguchi
*/
public final class Ring {
private final Map,Object> components = new HashMap<>();
private static final ThreadLocal instances = new ThreadLocal<>();
private Ring() {}
public static void add( Class clazz, T instance ) {
assert !get().components.containsKey(clazz);
get().components.put(clazz,instance);
}
@SuppressWarnings({"unchecked"})
public static void add( T o ) {
add((Class)o.getClass(),o);
}
public static T get( Class key ) {
@SuppressWarnings({"unchecked"})
T t = (T)get().components.get(key);
if(t==null) {
try {
Constructor c = key.getDeclaredConstructor();
c.setAccessible(true);
t = c.newInstance();
if(!get().components.containsKey(key))
// many components register themselves.
add(key,t);
} catch (ReflectiveOperationException e) {
throw new Error(e);
}
}
assert t!=null;
return t;
}
/**
* An instance is associated with a thread.
*/
public static Ring get() {
return instances.get();
}
/**
* Starts a new scope.
*/
public static Ring begin() {
Ring r = null;
synchronized (instances) {
r = instances.get();
instances.set(new Ring());
}
return r;
}
/**
* Ends a scope.
*/
public static void end(Ring old) {
synchronized (instances) {
instances.remove();
instances.set(old);
}
}
}