1 files changed, 121 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/remote/util/DigestUtil.java b/src/main/java/com/google/devtools/build/lib/remote/util/DigestUtil.java
new file mode 100644
index 0000000000..afd31ccdeb
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+++ b/src/main/java/com/google/devtools/build/lib/remote/util/DigestUtil.java
@@ -0,0 +1,121 @@
+// Copyright 2017 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.remote.util;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Preconditions;
+import com.google.common.hash.HashCode;
+import com.google.devtools.build.lib.actions.ActionInput;
+import com.google.devtools.build.lib.actions.MetadataProvider;
+import com.google.devtools.build.lib.actions.cache.DigestUtils;
+import com.google.devtools.build.lib.actions.cache.Metadata;
+import com.google.devtools.build.lib.actions.cache.VirtualActionInput;
+import com.google.devtools.build.lib.vfs.FileSystem.HashFunction;
+import com.google.devtools.build.lib.vfs.Path;
+import com.google.devtools.remoteexecution.v1test.Action;
+import com.google.devtools.remoteexecution.v1test.Digest;
+import com.google.protobuf.Message;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+/** Utility methods to work with {@link Digest}. */
+public class DigestUtil {
+
+  /**
+   * A special type of Digest that is used only as a remote action cache key. This is a separate
+   * type in order to prevent accidentally using other Digests as action keys.
+   */
+  public static final class ActionKey {
+    private final Digest digest;
+
+    public Digest getDigest() {
+      return digest;
+    }
+
+    private ActionKey(Digest digest) {
+      this.digest = digest;
+    }
+  }
+
+  private final HashFunction hashFn;
+
+  public DigestUtil(HashFunction hashFn) {
+    this.hashFn = hashFn;
+  }
+
+  public Digest compute(byte[] blob) {
+    return buildDigest(hashFn.getHash().hashBytes(blob).toString(), blob.length);
+  }
+
+  public Digest compute(Path file) throws IOException {
+    long fileSize = file.getFileSize();
+    byte[] digest = DigestUtils.getDigestOrFail(file, fileSize);
+    return buildDigest(digest, fileSize);
+  }
+
+  public Digest compute(VirtualActionInput input) throws IOException {
+    ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+    input.writeTo(buffer);
+    return compute(buffer.toByteArray());
+  }
+
+  /**
+   * Computes a digest of the given proto message. Currently, we simply rely on message output as
+   * bytes, but this implementation relies on the stability of the proto encoding, in particular
+   * between different platforms and languages. TODO(olaola): upgrade to a better implementation!
+   */
+  public Digest compute(Message message) {
+    return compute(message.toByteArray());
+  }
+
+  public Digest computeAsUtf8(String str) {
+    return compute(str.getBytes(UTF_8));
+  }
+
+  public DigestUtil.ActionKey computeActionKey(Action action) {
+    return new DigestUtil.ActionKey(compute(action));
+  }
+
+  /**
+   * Assumes that the given Digest is a valid digest of an Action, and creates an ActionKey wrapper.
+   * This should not be called on the client side!
+   */
+  public DigestUtil.ActionKey asActionKey(Digest digest) {
+    return new DigestUtil.ActionKey(digest);
+  }
+
+  public static Digest buildDigest(byte[] hash, long size) {
+    return buildDigest(HashCode.fromBytes(hash).toString(), size);
+  }
+
+  public static Digest buildDigest(String hexHash, long size) {
+    return Digest.newBuilder().setHash(hexHash).setSizeBytes(size).build();
+  }
+
+  public String toString(Digest digest) {
+    return digest.getHash() + "/" + digest.getSizeBytes();
+  }
+
+  public static Digest getFromInputCache(ActionInput input, MetadataProvider cache)
+      throws IOException {
+    Metadata metadata = cache.getMetadata(input);
+    Preconditions.checkNotNull(metadata, "Input cache %s returned no value for %s", cache, input);
+    Preconditions.checkNotNull(
+        metadata.getDigest(),
+        "Null digest for %s, possible directory. Data dependencies on directories are not allowed.",
+        input);
+    return buildDigest(metadata.getDigest(), metadata.getSize());
+  }
+}