/*
* 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<
Signal> {
private static final long
serialVersionUID = -221145131122459977L;
private static final
ConstantPool<
Signal>
pool = new
ConstantPool<
Signal>() {
@
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> {
SignalConstant(int
id,
String name) {
super(
id,
name);
}
}
}