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// Copyright 2014 Google Inc. 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.ActionInput;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.vfs.FileStatus;
import java.io.IOException;
import java.util.Collection;
/** Retrieves {@link Metadata} of {@link Artifact}s, and inserts virtual metadata as well. */
public interface MetadataHandler {
/**
* Returns metadata for the given artifact or null if it does not exist.
*
* @param artifact artifact
*
* @return metadata instance or null if metadata cannot be obtained.
*/
Metadata getMetadataMaybe(Artifact artifact);
/**
* Returns metadata for the given artifact or throws an exception if the
* metadata could not be obtained.
*
* @return metadata instance
*
* @throws IOException if metadata could not be obtained.
*/
Metadata getMetadata(Artifact artifact) throws IOException;
/** Sets digest for virtual artifacts (e.g. middlemen). {@code digest} must not be null. */
void setDigestForVirtualArtifact(Artifact artifact, Digest digest);
/**
* Injects provided digest into the metadata handler, simultaneously caching lstat() data as well.
*/
void injectDigest(ActionInput output, FileStatus statNoFollow, byte[] digest);
/**
* Marks an artifact as intentionally omitted. Acknowledges that this Artifact could have
* existed, but was intentionally not saved, most likely as an optimization.
*/
void markOmitted(ActionInput output);
/**
* Returns true iff artifact exists.
*
* <p>It is important to note that implementations may cache non-existence as a side effect
* of this method. If there is a possibility an artifact was intentionally omitted then
* {@link #artifactOmitted(Artifact)} should be checked first to avoid the side effect.</p>
*/
boolean artifactExists(Artifact artifact);
/** Returns true iff artifact is a regular file. */
boolean isRegularFile(Artifact artifact);
/** Returns true iff artifact was intentionally omitted (not saved). */
boolean artifactOmitted(Artifact artifact);
/**
* @return Whether the artifact's data was injected.
* @throws IOException if implementation tried to stat artifact which threw an exception.
* Technically, this means that the artifact could not have been injected, but by throwing
* here we save the caller trying to stat this file on their own and throwing the same
* exception. Implementations are not guaranteed to throw in this case if they are able to
* determine that the artifact is not injected without statting it.
*/
boolean isInjected(Artifact artifact) throws IOException;
/** Discards all metadata for the given artifacts, presumably because they will be modified. */
void discardMetadata(Collection<Artifact> artifactList);
}
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