io.netty.util.Signal Maven / Gradle / Ivy
/*
* Copyright 2012 The Netty Project
*
* The Netty Project 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 io.netty.util;
/**
* A special {@link Error} which is used to signal some state or request by throwing it.
* {@link Signal} has an empty stack trace and has no cause to save the instantiation overhead.
*/
public final class Signal extends Error implements Constant {
private static final long serialVersionUID = -221145131122459977L;
private static final ConstantPool pool = new ConstantPool() {
@Override
protected Signal newConstant(int id, String name) {
return new Signal(id, name);
}
};
/**
* Returns the {@link Signal} of the specified name.
*/
public static Signal valueOf(String name) {
return pool.valueOf(name);
}
/**
* Shortcut of {@link #valueOf(String) valueOf(firstNameComponent.getName() + "#" + secondNameComponent)}.
*/
public static Signal valueOf(Class firstNameComponent, String secondNameComponent) {
return pool.valueOf(firstNameComponent, secondNameComponent);
}
private final SignalConstant constant;
/**
* Creates a new {@link Signal} with the specified {@code name}.
*/
private Signal(int id, String name) {
constant = new SignalConstant(id, name);
}
/**
* Check if the given {@link Signal} is the same as this instance. If not an {@link IllegalStateException} will
* be thrown.
*/
public void expect(Signal signal) {
if (this != signal) {
throw new IllegalStateException("unexpected signal: " + signal);
}
}
@Override
public Throwable initCause(Throwable cause) {
return this;
}
@Override
public Throwable fillInStackTrace() {
return this;
}
@Override
public int id() {
return constant.id();
}
@Override
public String name() {
return constant.name();
}
@Override
public boolean equals(Object obj) {
return this == obj;
}
@Override
public int hashCode() {
return System.identityHashCode(this);
}
@Override
public int compareTo(Signal other) {
if (this == other) {
return 0;
}
return constant.compareTo(other.constant);
}
@Override
public String toString() {
return name();
}
private static final class SignalConstant extends AbstractConstant {
SignalConstant(int id, String name) {
super(id, name);
}
}
}