com.google.devtools.build.lib.remote.ContentDigests.java Source code

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Here is the source code for com.google.devtools.build.lib.remote.ContentDigests.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.remote;

import com.google.common.hash.HashCode;
import com.google.common.hash.Hashing;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.remote.RemoteProtocol.Action;
import com.google.devtools.build.lib.remote.RemoteProtocol.ContentDigest;
import com.google.devtools.build.lib.vfs.Path;
import com.google.protobuf.ByteString;
import com.google.protobuf.Message;
import java.io.IOException;

/** Helper methods relating to computing ContentDigest messages for remote execution. */
@ThreadSafe
public final class ContentDigests {
    private ContentDigests() {
    }

    public static ContentDigest computeDigest(byte[] blob) {
        return buildDigest(Hashing.sha1().hashBytes(blob).asBytes(), blob.length);
    }

    // TODO(olaola): cache these in ActionInputFileCache!
    public static ContentDigest computeDigest(Path file) throws IOException {
        return buildDigest(file.getSHA1Digest(), file.getFileSize());
    }

    /**
     * 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 static ContentDigest computeDigest(Message message) {
        return computeDigest(message.toByteArray());
    }

    /**
     * A special type of ContentDigest that is used only as a remote action cache key. This is a
     * separate type in order to prevent accidentally using other ContentDigests as action keys.
     */
    public static final class ActionKey {
        private final ContentDigest digest;

        public ContentDigest getDigest() {
            return digest;
        }

        private ActionKey(ContentDigest digest) {
            this.digest = digest;
        }
    }

    public static ActionKey computeActionKey(Action action) {
        return new ActionKey(computeDigest(action));
    }

    /**
     * Assumes that the given ContentDigest is a valid digest of an Action, and creates an ActionKey
     * wrapper. This should not be called on the client side!
     */
    public static ActionKey unsafeActionKeyFromDigest(ContentDigest digest) {
        return new ActionKey(digest);
    }

    public static ContentDigest buildDigest(byte[] digest, long size) {
        ContentDigest.Builder b = ContentDigest.newBuilder();
        b.setDigest(ByteString.copyFrom(digest)).setSizeBytes(size);
        return b.build();
    }

    public static String toHexString(ContentDigest digest) {
        return HashCode.fromBytes(digest.getDigest().toByteArray()).toString();
    }

    public static String toString(ContentDigest digest) {
        return "<digest: " + toHexString(digest) + ", size: " + digest.getSizeBytes() + " bytes>";
    }
}