src/main/java/com/google/devtools/build/lib/worker/WorkerFilesHash.java


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// Copyright 2016 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.worker;

import com.google.common.hash.HashCode;
import com.google.common.hash.Hasher;
import com.google.common.hash.Hashing;
import com.google.devtools.build.lib.actions.ActionInput;
import com.google.devtools.build.lib.actions.ActionInputFileCache;
import java.io.IOException;
import java.nio.charset.Charset;

/**
 * Calculates the hash based on the files, which should be unchanged on disk for a worker to get
 * reused.
 */
public class WorkerFilesHash {

  public static HashCode getWorkerFilesHash(
      Iterable<? extends ActionInput> toolFiles, ActionInputFileCache actionInputFileCache)
      throws IOException {
    Hasher hasher = Hashing.sha256().newHasher();
    for (ActionInput tool : toolFiles) {
      hasher.putString(tool.getExecPathString(), Charset.defaultCharset());
      hasher.putBytes(actionInputFileCache.getMetadata(tool).getDigest());
    }
    return hasher.hash();
  }
}