io.grpc.Attributes Maven / Gradle / Ivy
/*
* Copyright 2015, gRPC Authors All rights reserved.
*
* 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 io.grpc;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.base.Objects;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
/**
* An immutable type-safe container of attributes.
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/1764")
@Immutable
public final class Attributes {
private final Map, Object> data;
public static final Attributes EMPTY = new Attributes(Collections., Object>emptyMap());
private Attributes(Map, Object> data) {
assert data != null;
this.data = data;
}
/**
* Gets the value for the key, or {@code null} if it's not present.
*/
@SuppressWarnings("unchecked")
@Nullable
public T get(Key key) {
return (T) data.get(key);
}
/**
* Returns set of keys stored in container.
*
* @return Set of Key objects.
*/
public Set> keys() {
return Collections.unmodifiableSet(data.keySet());
}
/**
* Create a new builder that is pre-populated with the content from a given container.
*/
public static Builder newBuilder(Attributes base) {
checkNotNull(base, "base");
return new Builder(base);
}
/**
* Create a new builder.
*/
public static Builder newBuilder() {
return new Builder(EMPTY);
}
/**
* Key for an key-value pair.
* @param type of the value in the key-value pair
*/
@Immutable
public static final class Key {
private final String name;
private Key(String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
/**
* Factory method for creating instances of {@link Key}.
*
* @param name the name of Key. Name collision, won't cause key collision.
* @param Key type
* @return Key object
*/
public static Key of(String name) {
return new Key(name);
}
}
@Override
public String toString() {
return data.toString();
}
/**
* Returns true if the given object is also a {@link Attributes} with an equal attribute values.
*
* Note that if a stored values are mutable, it is possible for two objects to be considered
* equal at one point in time and not equal at another (due to concurrent mutation of attribute
* values).
*
* @param o an object.
* @return true if the given object is a {@link Attributes} equal attributes.
*/
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Attributes that = (Attributes) o;
if (data.size() != that.data.size()) {
return false;
}
for (Entry, Object> e : data.entrySet()) {
if (!that.data.containsKey(e.getKey())) {
return false;
}
if (!Objects.equal(e.getValue(), that.data.get(e.getKey()))) {
return false;
}
}
return true;
}
/**
* Returns a hash code for the attributes.
*
* Note that if a stored values are mutable, it is possible for two objects to be considered
* equal at one point in time and not equal at another (due to concurrent mutation of attribute
* values).
*
* @return a hash code for the attributes map.
*/
@Override
public int hashCode() {
return data.hashCode();
}
/**
* The helper class to build an Attributes instance.
*/
public static final class Builder {
private Attributes base;
private Map, Object> newdata;
private Builder(Attributes base) {
assert base != null;
this.base = base;
}
private Map, Object> data(int size) {
if (newdata == null) {
newdata = new IdentityHashMap, Object>(size);
}
return newdata;
}
public Builder set(Key key, T value) {
data(1).put(key, value);
return this;
}
public Builder setAll(Attributes other) {
data(other.data.size()).putAll(other.data);
return this;
}
/**
* Build the attributes.
*/
public Attributes build() {
if (newdata != null) {
for (Entry, Object> entry : base.data.entrySet()) {
if (!newdata.containsKey(entry.getKey())) {
newdata.put(entry.getKey(), entry.getValue());
}
}
base = new Attributes(newdata);
newdata = null;
}
return base;
}
}
}