Implemented a "--experimental_repository_cache" option as the first step to
caching external repositories (go/bazel-cache)

The option is categorized as hidden because it is a no-op.

--
MOS_MIGRATED_REVID=135006114

src/main/java/com/google/devtools/build/lib/BUILD

diff --git a/src/main/java/com/google/devtools/build/lib/BUILD b/src/main/java/com/google/devtools/build/lib/BUILD
index 45aa1c3..f9429f1 100644
--- a/src/main/java/com/google/devtools/build/lib/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/BUILD
@@ -670,6 +670,7 @@
         "//src/main/java/com/google/devtools/build/lib:vfs",
         "//src/main/java/com/google/devtools/build/lib/bazel/repository/downloader",
         "//src/main/java/com/google/devtools/build/skyframe",
+        "//src/main/java/com/google/devtools/common/options",
         "//third_party:aether",
         "//third_party:apache_commons_compress",
         "//third_party:guava",

src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java b/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
index 365632d..dad3d93 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/BazelRepositoryModule.java
@@ -14,6 +14,7 @@
 
 package com.google.devtools.build.lib.bazel;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
@@ -28,6 +29,7 @@
 import com.google.devtools.build.lib.bazel.repository.MavenServerRepositoryFunction;
 import com.google.devtools.build.lib.bazel.repository.NewGitRepositoryFunction;
 import com.google.devtools.build.lib.bazel.repository.NewHttpArchiveFunction;
+import com.google.devtools.build.lib.bazel.repository.RepositoryOptions;
 import com.google.devtools.build.lib.bazel.repository.skylark.SkylarkRepositoryFunction;
 import com.google.devtools.build.lib.bazel.repository.skylark.SkylarkRepositoryModule;
 import com.google.devtools.build.lib.bazel.rules.android.AndroidNdkRepositoryFunction;
@@ -62,6 +64,7 @@
 import com.google.devtools.build.lib.util.io.TimestampGranularityMonitor;
 import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
+import com.google.devtools.common.options.OptionsBase;
 import com.google.devtools.common.options.OptionsProvider;
 
 import java.util.Map.Entry;
@@ -170,4 +173,11 @@
     delegator.setClientEnvironment(env.getClientEnv());
     skylarkRepositoryFunction.setCommandEnvironment(env);
   }
+
+  @Override
+  public Iterable<Class<? extends OptionsBase>> getCommandOptions(Command command) {
+    return "fetch".equals(command.name()) || "build".equals(command.name())
+        ? ImmutableList.of(RepositoryOptions.class)
+        : ImmutableList.<Class<? extends OptionsBase>>of();
+  }
 }

src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryOptions.java

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryOptions.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryOptions.java
new file mode 100644
index 0000000..84b1fa2
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryOptions.java
@@ -0,0 +1,35 @@
+//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.bazel.repository;
+
+import com.google.devtools.build.lib.util.OptionsUtils;
+import com.google.devtools.build.lib.vfs.PathFragment;
+import com.google.devtools.common.options.Option;
+import com.google.devtools.common.options.OptionsBase;
+
+/**
+ * Command-line options for repositories.
+ */
+public class RepositoryOptions extends OptionsBase {
+
+  @Option(name = "experimental_repository_cache",
+          defaultValue = "null",
+          category = "hidden",
+          converter = OptionsUtils.PathFragmentConverter.class,
+          help = "Specifies the cache location of the downloaded values obtained "
+              + "during the fetching of external repositories.")
+  public PathFragment experimentalRepositoryCache;
+
+}
\ No newline at end of file