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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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 org.elasticsearch.common.io.stream;
import java.util.HashMap;
import java.util.Map;
/**
* Registry for {@link NamedWriteable} objects. Allows to register and retrieve prototype instances of writeable objects
* given their name.
*/
public class NamedWriteableRegistry {
private final Map<Class<?>, InnerRegistry<?>> registry = new HashMap<>();
/**
* Register a {@link NamedWriteable} given its category, its name, and a function to read it from the stream.
*
* This method suppresses the rawtypes warning because it intentionally using NamedWriteable instead of {@code NamedWriteable<T>} so it
* is easier to use and because we might be able to drop the type parameter from NamedWriteable entirely some day.
*/
@SuppressWarnings("rawtypes")
public synchronized <T extends NamedWriteable> void register(Class<T> categoryClass, String name,
Writeable.Reader<? extends T> reader) {
@SuppressWarnings("unchecked")
InnerRegistry<T> innerRegistry = (InnerRegistry<T>) registry.get(categoryClass);
if (innerRegistry == null) {
innerRegistry = new InnerRegistry<>(categoryClass);
registry.put(categoryClass, innerRegistry);
}
innerRegistry.register(name, reader);
}
/**
* Returns a prototype of the {@link NamedWriteable} object identified by the name provided as argument and its category
*/
public synchronized <T> Writeable.Reader<? extends T> getReader(Class<T> categoryClass, String name) {
@SuppressWarnings("unchecked")
InnerRegistry<T> innerRegistry = (InnerRegistry<T>)registry.get(categoryClass);
if (innerRegistry == null) {
throw new IllegalArgumentException("unknown named writeable category [" + categoryClass.getName() + "]");
}
return innerRegistry.getReader(name);
}
private static class InnerRegistry<T> {
private final Map<String, Writeable.Reader<? extends T>> registry = new HashMap<>();
private final Class<T> categoryClass;
private InnerRegistry(Class<T> categoryClass) {
this.categoryClass = categoryClass;
}
private void register(String name, Writeable.Reader<? extends T> reader) {
Writeable.Reader<? extends T> existingReader = registry.get(name);
if (existingReader != null) {
throw new IllegalArgumentException(
"named writeable [" + categoryClass.getName() + "][" + name + "] is already registered by [" + reader + "]");
}
registry.put(name, reader);
}
private Writeable.Reader<? extends T> getReader(String name) {
Writeable.Reader<? extends T> reader = registry.get(name);
if (reader == null) {
throw new IllegalArgumentException("unknown named writeable [" + categoryClass.getName() + "][" + name + "]");
}
return reader;
}
}
}
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