| // Copyright 2020 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 com.google.common.base.Preconditions.checkNotNull; |
| |
| import build.bazel.remote.execution.v2.Digest; |
| import com.google.common.hash.HashFunction; |
| import com.google.common.hash.Hasher; |
| import java.io.FilterOutputStream; |
| import java.io.IOException; |
| import java.io.OutputStream; |
| |
| /** |
| * An {@link OutputStream} that maintains a {@link Digest} of the data written to it. |
| * |
| * <p>Similar to Guava's {@link com.google.common.hash.HashingOutputStream}, but for computing the |
| * {@link Digest} of the written data as specified by the remote execution protocol. |
| */ |
| public final class DigestOutputStream extends FilterOutputStream { |
| private final Hasher hasher; |
| private long size = 0; |
| |
| /** |
| * Creates an output stream that creates an {@link Digest} using the given {@link HashFunction}, |
| * and forwards all data written to it to the underlying {@link OutputStream}. |
| * |
| * <p>The {@link OutputStream} should not be written to before or after the hand-off. |
| */ |
| public DigestOutputStream(HashFunction hashFunction, OutputStream out) { |
| super(checkNotNull(out)); |
| this.hasher = checkNotNull(hashFunction.newHasher()); |
| } |
| |
| @Override |
| public void write(int b) throws IOException { |
| size++; |
| hasher.putByte((byte) b); |
| out.write(b); |
| } |
| |
| @Override |
| public void write(byte[] bytes, int off, int len) throws IOException { |
| size += len; |
| hasher.putBytes(bytes, off, len); |
| out.write(bytes, off, len); |
| } |
| |
| /** |
| * Returns the {@link Digest} of the data written to this stream. The result is unspecified if |
| * this method is called more than once on the same instance. |
| */ |
| public Digest digest() { |
| return Digest.newBuilder().setHash(hasher.hash().toString()).setSizeBytes(size).build(); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| out.close(); |
| } |
| } |