java.lang.InheritableThreadLocal Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 java.lang;
/**
* A thread-local variable whose value is passed from parent to child thread. By
* default, the value of an inheritable thread-local variable of a child thread
* is initialized with the value of the parent thread's variable at thread
* creation time. However, subclasses may override {code #childValue(Object)}
* to provide an arbitrary function for passing the value of a parent's
* thread-local variable to the child's thread-local variable.
*
* @see java.lang.Thread
* @see java.lang.ThreadLocal
*/
public class InheritableThreadLocal extends ThreadLocal {
/**
* Creates a new inheritable thread-local variable.
*/
public InheritableThreadLocal() {
}
/**
* Computes the initial value of this thread-local variable for the child
* thread given the parent thread's value. Called from the parent thread when
* creating a child thread. The default implementation returns the parent
* thread's value.
*
* @param parentValue the value of the variable in the parent thread.
* @return the initial value of the variable for the child thread.
*/
protected T childValue(T parentValue) {
return parentValue;
}
@Override
Values values(Thread current) {
return current.inheritableValues;
}
@Override
Values initializeValues(Thread current) {
return current.inheritableValues = new Values();
}
}