Add easy access to MessageDigests in DigestHashFunction

Move the message-digest cloning to DigestHashFunction and out of Fingerprint, to make it possible to configure Fingerprint to use different hash functions. We keep the default MD5 for now, we'd like it to use the global default but want to isolate the configuration change from any change adding potential contention.

RELNOTES: None.
PiperOrigin-RevId: 208502993

3 files changed, 78 insertions, 13 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/util/FingerprintTest.java b/src/test/java/com/google/devtools/build/lib/util/FingerprintTest.java
index 372b48d80c..b3fd3c4ef2 100644
--- a/src/test/java/com/google/devtools/build/lib/util/FingerprintTest.java
+++ b/src/test/java/com/google/devtools/build/lib/util/FingerprintTest.java
@@ -58,7 +58,7 @@ public class FingerprintTest {
   public void bytesFingerprint() {
     assertThat(new Fingerprint().addBytes("Hello World!".getBytes(UTF_8)).hexDigestAndReset())
         .isEqualTo("ed076287532e86365e841e92bfc50d8c");
-    assertThat(Fingerprint.md5Digest("Hello World!"))
+    assertThat(Fingerprint.getHexDigest("Hello World!"))
         .isEqualTo("ed076287532e86365e841e92bfc50d8c");
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/DigestHashFunctionTest.java b/src/test/java/com/google/devtools/build/lib/vfs/DigestHashFunctionGlobalsTest.java
index 1e4044bd31..77f7b62b21 100644
--- a/src/test/java/com/google/devtools/build/lib/vfs/DigestHashFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/vfs/DigestHashFunctionGlobalsTest.java
@@ -29,7 +29,7 @@ import org.junit.runners.JUnit4;
  * equality.
  */
 @RunWith(JUnit4.class)
-public class DigestHashFunctionTest {
+public class DigestHashFunctionGlobalsTest {
   private final DigestFunctionConverter converter = new DigestFunctionConverter();
 
   @Before
@@ -64,22 +64,26 @@ public class DigestHashFunctionTest {
 
   @Test
   public void lateRegistrationGetsPickedUpByConverter() throws Exception {
-    DigestHashFunction.register(Hashing.goodFastHash(32), "goodFastHash32");
+    DigestHashFunction.register(Hashing.goodFastHash(32), "SHA-512");
 
-    assertThat(converter.convert("goodFastHash32")).isSameAs(converter.convert("GOODFASTHASH32"));
+    assertThat(converter.convert("SHA-512")).isSameAs(converter.convert("sha-512"));
   }
 
   @Test
   public void lateRegistrationWithAlternativeNamesGetsPickedUpByConverter() throws Exception {
-    DigestHashFunction.register(
-        Hashing.goodFastHash(64), "goodFastHash64", "goodFastHash-64", "good-fast-hash-64");
-
-    assertThat(converter.convert("goodFastHash64")).isSameAs(converter.convert("GOODFASTHASH64"));
-    assertThat(converter.convert("goodFastHash64")).isSameAs(converter.convert("goodFastHash-64"));
-    assertThat(converter.convert("goodFastHash64"))
-        .isSameAs(converter.convert("good-fast-hash-64"));
-    assertThat(converter.convert("goodFastHash64"))
-        .isSameAs(converter.convert("GOOD-fast-HASH-64"));
+    DigestHashFunction.register(Hashing.goodFastHash(64), "SHA-384", "SHA384", "SHA_384");
+
+    assertThat(converter.convert("SHA-384")).isSameAs(converter.convert("SHA-384"));
+    assertThat(converter.convert("Sha-384")).isSameAs(converter.convert("SHA-384"));
+    assertThat(converter.convert("sha-384")).isSameAs(converter.convert("SHA-384"));
+
+    assertThat(converter.convert("SHA384")).isSameAs(converter.convert("SHA-384"));
+    assertThat(converter.convert("Sha384")).isSameAs(converter.convert("SHA-384"));
+    assertThat(converter.convert("sha384")).isSameAs(converter.convert("SHA-384"));
+
+    assertThat(converter.convert("SHA_384")).isSameAs(converter.convert("SHA-384"));
+    assertThat(converter.convert("Sha_384")).isSameAs(converter.convert("SHA-384"));
+    assertThat(converter.convert("sha_384")).isSameAs(converter.convert("SHA-384"));
   }
 
   @Test
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/DigestHashFunctionsTest.java b/src/test/java/com/google/devtools/build/lib/vfs/DigestHashFunctionsTest.java
new file mode 100644
index 0000000000..6b3b19923d
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/vfs/DigestHashFunctionsTest.java
@@ -0,0 +1,61 @@
+// Copyright 2018 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.vfs;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.ImmutableList;
+import java.nio.charset.StandardCharsets;
+import java.util.Collection;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameter;
+import org.junit.runners.Parameterized.Parameters;
+
+/**
+ * Tests different {@link DigestHashFunction} for consistency between the MessageDigests and the
+ * HashFunctions that it exposes.
+ */
+@RunWith(Parameterized.class)
+public class DigestHashFunctionsTest {
+  @Parameters(name = "{index}: digestHashFunction={0}")
+  public static Collection<DigestHashFunction[]> hashFunctions() {
+    // TODO(b/112537387): Remove the array-ification and return Collection<DigestHashFunction>. This
+    // is possible in Junit4.12, but 4.11 requires the array. Bazel 0.18 will have Junit4.12, so
+    // this can change then.
+    return DigestHashFunction.getPossibleHashFunctions()
+        .stream()
+        .map(dhf -> new DigestHashFunction[] {dhf})
+        .collect(ImmutableList.toImmutableList());
+  }
+
+  @Parameter public DigestHashFunction digestHashFunction;
+
+  private void assertHashFunctionAndMessageDigestEquivalentForInput(byte[] input) {
+    byte[] hashFunctionOutput = digestHashFunction.getHashFunction().hashBytes(input).asBytes();
+    byte[] messageDigestOutput = digestHashFunction.cloneOrCreateMessageDigest().digest(input);
+    assertThat(hashFunctionOutput).isEqualTo(messageDigestOutput);
+  }
+
+  @Test
+  public void emptyDigestIsConsistent() {
+    assertHashFunctionAndMessageDigestEquivalentForInput(new byte[] {});
+  }
+
+  @Test
+  public void shortDigestIsConsistent() {
+    assertHashFunctionAndMessageDigestEquivalentForInput("Bazel".getBytes(StandardCharsets.UTF_8));
+  }
+}