com.netflix.zuul.Attrs Maven / Gradle / Ivy
/*
* Copyright 2020 Netflix, Inc.
*
* Licensed 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 com.netflix.zuul;
import com.google.common.annotations.VisibleForTesting;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.function.BiConsumer;
import javax.annotation.Nullable;
/**
* A heterogeneous map of attributes.
*
* Implementation Note: this class is not a proper Map or Collection, in order to encourage callers
* to refer to the keys by their literal name. In the past, finding where a Key was used was difficult,
* so this class is somewhat of an experiment to try to make tracking down usage easier. If it becomes
* too onerous to use this, consider making this class extend AbstractMap.
*/
public final class Attrs {
final Map, Object> storage = new IdentityHashMap<>();
public static Key newKey(String keyName) {
return new Key<>(keyName);
}
public static final class Key {
private final String name;
/**
* Returns the value in the attributes, or {@code null} if absent.
*/
@Nullable
@SuppressWarnings("unchecked")
public T get(Attrs attrs) {
Objects.requireNonNull(attrs, "attrs");
return (T) attrs.storage.get(this);
}
/**
* Returns the value in the attributes or {@code defaultValue} if absent.
* @throws NullPointerException if defaultValue is null.
*/
@SuppressWarnings("unchecked")
public T getOrDefault(Attrs attrs, T defaultValue) {
Objects.requireNonNull(attrs, "attrs");
Objects.requireNonNull(defaultValue, "defaultValue");
T result = (T) attrs.storage.get(this);
if (result != null) {
return result;
}
return defaultValue;
}
public void put(Attrs attrs, T value) {
Objects.requireNonNull(attrs, "attrs");
Objects.requireNonNull(value);
attrs.storage.put(this, value);
}
public String name() {
return name;
}
private Key(String name) {
this.name = Objects.requireNonNull(name);
}
@Override
public String toString() {
return "Key{" + name + '}';
}
}
private Attrs() {}
public static Attrs newInstance() {
return new Attrs();
}
public Set> keySet() {
return Collections.unmodifiableSet(new LinkedHashSet<>(storage.keySet()));
}
public void forEach(BiConsumer, Object> consumer) {
storage.forEach(consumer);
}
public int size() {
return storage.size();
}
@Override
public String toString() {
return "Attrs{" + storage + '}';
}
@Override
@VisibleForTesting
public boolean equals(Object other) {
if (!(other instanceof Attrs)) {
return false;
}
Attrs that = (Attrs) other;
return Objects.equals(this.storage, that.storage);
}
@Override
@VisibleForTesting
public int hashCode() {
return Objects.hash(storage);
}
}