| // Copyright 2014 The Bazel 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 com.google.devtools.build.skyframe; |
| |
| import java.io.Serializable; |
| |
| /** |
| * A {@link SkyKey} is effectively a pair (type, name) that identifies a Skyframe value. |
| * |
| * <p>SkyKey implementations are heavily used as map keys. Thus, they should have fast {@link |
| * #hashCode} implementations (cached if necessary). The same SkyKey may be created multiple times |
| * by different {@code SkyFunction}s requesting it, and so it should have effective interning. There |
| * will likely be more SkyKeys on the JVM heap than any other non-native type, so be mindful of |
| * memory usage (in particular object wrapper size and memory alignment)! Typically the |
| * implementation should have a fixed {@link #functionName} implementation and return itself as the |
| * {@link #argument} in order to reduce the cost of wrapper objects. |
| */ |
| public interface SkyKey extends Serializable { |
| SkyFunctionName functionName(); |
| |
| Object argument(); |
| } |