| /* |
| * 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 com.google.common.base.Objects; |
| import com.google.common.base.Preconditions; |
| import java.util.Collections; |
| import java.util.HashMap; |
| 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 HashMap<Key<?>, Object> data = new HashMap<Key<?>, Object>(); |
| |
| public static final Attributes EMPTY = new Attributes(); |
| |
| private Attributes() { |
| } |
| |
| /** |
| * Gets the value for the key, or {@code null} if it's not present. |
| */ |
| @SuppressWarnings("unchecked") |
| @Nullable |
| public <T> T get(Key<T> key) { |
| return (T) data.get(key); |
| } |
| |
| /** |
| * Returns set of keys stored in container. |
| * |
| * @return Set of Key objects. |
| */ |
| public Set<Key<?>> 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) { |
| return newBuilder().setAll(base); |
| } |
| |
| /** |
| * Create a new builder. |
| */ |
| public static Builder newBuilder() { |
| return new Builder(); |
| } |
| |
| /** |
| * Key for an key-value pair. |
| * @param <T> type of the value in the key-value pair |
| */ |
| @Immutable |
| public static final class Key<T> { |
| 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 <T> Key type |
| * @return Key object |
| */ |
| public static <T> Key<T> of(String name) { |
| return new Key<T>(name); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return data.toString(); |
| } |
| |
| /** |
| * Returns true if the given object is also a {@link Attributes} with an equal attribute values. |
| * |
| * <p>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; |
| return Objects.equal(data, that.data); |
| } |
| |
| /** |
| * Returns a hash code for the attributes. |
| * |
| * <p>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 product; |
| |
| private Builder() { |
| this.product = new Attributes(); |
| } |
| |
| public <T> Builder set(Key<T> key, T value) { |
| product.data.put(key, value); |
| return this; |
| } |
| |
| public <T> Builder setAll(Attributes other) { |
| product.data.putAll(other.data); |
| return this; |
| } |
| |
| /** |
| * Build the attributes. Can only be called once. |
| */ |
| public Attributes build() { |
| Preconditions.checkState(product != null, "Already built"); |
| Attributes result = product; |
| product = null; |
| return result; |
| } |
| } |
| } |