Add --experimental_multi_threaded_digest which lets DigestUtils use multiple threads when calculating the MD5 hash even for large files. Might improve performance when using an SSD.

Fixes #835 and #1210.

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MOS_MIGRATED_REVID=124128233

1 files changed, 40 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/ssd/SsdModule.java b/src/main/java/com/google/devtools/build/lib/ssd/SsdModule.java
new file mode 100644
index 0000000000..a41a3baa38
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/ssd/SsdModule.java
@@ -0,0 +1,40 @@
+// 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.ssd;
+
+import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.actions.cache.DigestUtils;
+import com.google.devtools.build.lib.runtime.BlazeModule;
+import com.google.devtools.build.lib.runtime.Command;
+import com.google.devtools.common.options.OptionsBase;
+import com.google.devtools.common.options.OptionsProvider;
+
+/**
+ * BlazeModule that applies optimizations to Bazel's internals in order to improve performance when
+ * using an SSD.
+ */
+public final class SsdModule extends BlazeModule {
+  @Override
+  public Iterable<Class<? extends OptionsBase>> getCommandOptions(Command command) {
+    return ImmutableList.<Class<? extends OptionsBase>>of(SsdOptions.class);
+  }
+
+  @Override
+  public void handleOptions(OptionsProvider optionsProvider) {
+    SsdOptions options = optionsProvider.getOptions(SsdOptions.class);
+    if (options.experimentalMultiThreadedDigest) {
+      DigestUtils.setMultiThreadedDigest(options.experimentalMultiThreadedDigest);
+    }
+  }
+}