| // 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.lib.actions.cache; |
| |
| import com.google.devtools.build.lib.actions.FileStateType; |
| import javax.annotation.Nullable; |
| |
| /** |
| * An interface to represent the state of a file system object for the execution phase. This is not |
| * used by Skyframe for invalidation, it is primarily used by the action cache and the various |
| * {@link com.google.devtools.build.lib.exec.SpawnRunner} implementations. |
| */ |
| public interface Metadata { |
| /** |
| * Marker interface for singleton implementations of the Metadata interface. This is only needed |
| * for a correct implementation of {@code equals}. |
| */ |
| public interface Singleton { |
| } |
| |
| /** |
| * The type of the underlying file system object. If it is a regular file, then it is |
| * guaranteed to have a digest. Otherwise it does not have a digest. |
| */ |
| FileStateType getType(); |
| |
| /** |
| * Returns a digest of the content of the underlying file system object; must always return a |
| * non-null value for instances of type {@link FileStateType#REGULAR_FILE}. Otherwise may return |
| * null. |
| * |
| * <p>All instances of this interface must either have a digest or return a last-modified time. |
| * Clients should prefer using the digest for content identification (e.g., for caching), and only |
| * fall back to the last-modified time if no digest is available. |
| * |
| * <p>The return value is owned by this object and must not be modified. |
| */ |
| @Nullable |
| byte[] getDigest(); |
| |
| /** Returns the file's size, or 0 if the underlying file system object is not a file. */ |
| // TODO(ulfjack): Throw an exception if it's not a file. |
| long getSize(); |
| |
| /** |
| * Returns the last modified time; see the documentation of {@link #getDigest} for when this can |
| * and should be called. |
| */ |
| long getModifiedTime(); |
| |
| /** |
| * Index used to resolve remote files. |
| * |
| * <p>0 indicates that no such information is available which can mean that it's either a local |
| * file or empty. |
| */ |
| default int getLocationIndex() { |
| return 0; |
| } |
| } |