/*
* Copyright 2014 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.resolver;
import io.netty.util.concurrent.
EventExecutor;
import io.netty.util.concurrent.
Future;
import io.netty.util.concurrent.
Promise;
import io.netty.util.internal.
UnstableApi;
import java.util.
List;
import static io.netty.util.internal.
ObjectUtil.*;
/**
* A skeletal {@link NameResolver} implementation.
*/
@
UnstableApi
public abstract class
SimpleNameResolver<T> implements
NameResolver<T> {
private final
EventExecutor executor;
/**
* @param executor the {@link EventExecutor} which is used to notify the listeners of the {@link Future} returned
* by {@link #resolve(String)}
*/
protected
SimpleNameResolver(
EventExecutor executor) {
this.
executor =
checkNotNull(
executor, "executor");
}
/**
* Returns the {@link EventExecutor} which is used to notify the listeners of the {@link Future} returned
* by {@link #resolve(String)}.
*/
protected
EventExecutor executor() {
return
executor;
}
@
Override
public final
Future<T>
resolve(
String inetHost) {
final
Promise<T>
promise =
executor().
newPromise();
return
resolve(
inetHost,
promise);
}
@
Override
public
Future<T>
resolve(
String inetHost,
Promise<T>
promise) {
checkNotNull(
promise, "promise");
try {
doResolve(
inetHost,
promise);
return
promise;
} catch (
Exception e) {
return
promise.
setFailure(
e);
}
}
@
Override
public final
Future<
List<T>>
resolveAll(
String inetHost) {
final
Promise<
List<T>>
promise =
executor().
newPromise();
return
resolveAll(
inetHost,
promise);
}
@
Override
public
Future<
List<T>>
resolveAll(
String inetHost,
Promise<
List<T>>
promise) {
checkNotNull(
promise, "promise");
try {
doResolveAll(
inetHost,
promise);
return
promise;
} catch (
Exception e) {
return
promise.
setFailure(
e);
}
}
/**
* Invoked by {@link #resolve(String)} to perform the actual name resolution.
*/
protected abstract void
doResolve(
String inetHost,
Promise<T>
promise) throws
Exception;
/**
* Invoked by {@link #resolveAll(String)} to perform the actual name resolution.
*/
protected abstract void
doResolveAll(
String inetHost,
Promise<
List<T>>
promise) throws
Exception;
@
Override
public void
close() { }
}