oshi.annotation.concurrent.Immutable Maven / Gradle / Ivy
/*
* Copyright 2020-2022 The OSHI Project Contributors
* SPDX-License-Identifier: MIT
*/
package oshi.annotation.concurrent;
import java.lang.annotation.Documented;
/**
* The presence of this annotation indicates that the author believes the class to be immutable and hence inherently
* thread-safe. An immutable class is one where the state of an instance cannot be seen to change. As a result
*
* - All public fields must be {@code final}
* - All public final reference fields are either {@code null} or refer to other immutable objects
* - Constructors and methods do not publish references to any potentially mutable internal state.
*
* Performance optimization may mean that instances of an immutable class may have mutable internal state. The critical
* point is that callers cannot tell the difference. For example {@link String} is an immutable class, despite having an
* internal int that is non-final but used as a cache for {@link String#hashCode()}.
*
* Immutable objects are inherently thread-safe; they may be passed between threads or published without
* synchronization.
*
* This annotation is intended for internal use in OSHI as a temporary workaround until it is available in
* {@code jakarta.annotations}.
*/
@Documented
public @interface Immutable {
}