org.springframework.core.NamedThreadLocal Maven / Gradle / Ivy
/*
* Copyright 2002-2023 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
*
* https://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.core;
import java.util.Objects;
import java.util.function.Supplier;
import org.springframework.util.Assert;
/**
* {@link ThreadLocal} subclass that exposes a specified name
* as {@link #toString()} result (allowing for introspection).
*
* @author Juergen Hoeller
* @author Qimiao Chen
* @since 2.5.2
* @param the value type
* @see NamedInheritableThreadLocal
*/
public class NamedThreadLocal extends ThreadLocal {
private final String name;
/**
* Create a new NamedThreadLocal with the given name.
* @param name a descriptive name for this ThreadLocal
*/
public NamedThreadLocal(String name) {
Assert.hasText(name, "Name must not be empty");
this.name = name;
}
@Override
public String toString() {
return this.name;
}
/**
* Create a named thread local variable. The initial value of the variable is
* determined by invoking the {@code get} method on the {@code Supplier}.
* @param the type of the named thread local's value
* @param name a descriptive name for the thread local
* @param supplier the supplier to be used to determine the initial value
* @return a new named thread local
* @since 6.1
*/
public static ThreadLocal withInitial(String name, Supplier supplier) {
return new SuppliedNamedThreadLocal<>(name, supplier);
}
/**
* An extension of NamedThreadLocal that obtains its initial value from
* the specified {@code Supplier}.
* @param the type of the named thread local's value
*/
private static final class SuppliedNamedThreadLocal extends NamedThreadLocal {
private final Supplier supplier;
SuppliedNamedThreadLocal(String name, Supplier supplier) {
super(name);
this.supplier = Objects.requireNonNull(supplier);
}
@Override
protected T initialValue() {
return this.supplier.get();
}
}
}