Introduce option flag experimental_enable_tools_defaults_package.

Default value is true, and behavior related to //tools/defaults package is not
changed. If set it to false, then in-memory Dfaultpacked will not be created.

RELNOTES:none
PiperOrigin-RevId: 205643628

src/main/java/com/google/devtools/build/lib/pkgcache/PackageCacheOptions.java

@@ -27,6 +27,7 @@
 import com.google.devtools.common.options.Option;
 import com.google.devtools.common.options.OptionDocumentationCategory;
 import com.google.devtools.common.options.OptionEffectTag;
+import com.google.devtools.common.options.OptionMetadataTag;
 import com.google.devtools.common.options.OptionsBase;
 import com.google.devtools.common.options.OptionsParsingException;
 import java.util.List;
@@ -161,6 +162,17 @@ public String getTypeDescription() {
   )
   public boolean checkOutputFiles;
 
+  @Option(
+      name = "experimental_enable_tools_defaults_package",
+      defaultValue = "true",
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = {OptionEffectTag.AFFECTS_OUTPUTS},
+      metadataTags = {OptionMetadataTag.EXPERIMENTAL},
+      help =
+          "If true, Blaze constructs an in-memory //tools/defaults package based on the command"
+              + " line options. If false, //tools/defaults is resolved as a regular package.")
+  public boolean experimentalInMemoryToolsDefaultsPackage;
+
   /**
    * A converter from strings containing comma-separated names of packages to lists of strings.
    */

src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java

@@ -438,14 +438,14 @@ public SkyValue compute(SkyKey key, Environment env) throws PackageFunctionExcep
     Path buildFilePath = buildFileRootedPath.asPath();
     String replacementContents = null;
 
-    if (!isDefaultsPackage(packageId)) {
-      buildFileValue = getBuildFileValue(env, buildFileRootedPath);
-      if (buildFileValue == null) {
+    if (isDefaultsPackage(packageId) && PrecomputedValue.isInMemoryToolsDefaults(env)) {
+      replacementContents = PrecomputedValue.DEFAULTS_PACKAGE_CONTENTS.get(env);
+      if (replacementContents == null) {
         return null;
       }
     } else {
-      replacementContents = PrecomputedValue.DEFAULTS_PACKAGE_CONTENTS.get(env);
-      if (replacementContents == null) {
+      buildFileValue = getBuildFileValue(env, buildFileRootedPath);
+      if (buildFileValue == null) {
         return null;
       }
     }

src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java

@@ -71,7 +71,9 @@ public SkyValue compute(SkyKey skyKey, Environment env)
     PathPackageLocator pkgLocator = PrecomputedValue.PATH_PACKAGE_LOCATOR.get(env);
 
     PackageIdentifier packageKey = (PackageIdentifier) skyKey.argument();
-    if (PackageFunction.isDefaultsPackage(packageKey)) {
+
+    if (PackageFunction.isDefaultsPackage(packageKey)
+        && PrecomputedValue.isInMemoryToolsDefaults(env)) {
       return PackageLookupValue.success(pkgLocator.getPathEntries().get(0), BuildFileName.BUILD);
     }
 

src/main/java/com/google/devtools/build/lib/skyframe/PrecomputedValue.java

@@ -79,6 +79,17 @@ public static <T> Injected injected(Precomputed<T> precomputed, T value) {
     return new Injected(precomputed, Suppliers.ofInstance(value));
   }
 
+  public static final Precomputed<Boolean> ENABLE_DEFAULTS_PACKAGE =
+      new Precomputed<>(Key.create("enable_default_pkg"));
+
+  // TODO(dbabkin): better to move this code to PrecomputedValueUtils.
+  // It will gone soon after removing tools/defaults
+  public static boolean isInMemoryToolsDefaults(SkyFunction.Environment env)
+      throws InterruptedException {
+    Boolean enableDefaultsPackage = PrecomputedValue.ENABLE_DEFAULTS_PACKAGE.get(env);
+    return Preconditions.checkNotNull(enableDefaultsPackage);
+  }
+
   public static final Precomputed<String> DEFAULTS_PACKAGE_CONTENTS =
       new Precomputed<>(Key.create("default_pkg"));
 

src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java

@@ -1107,7 +1107,14 @@ public void preparePackageLoading(
     setShowLoadingProgress(packageCacheOptions.showLoadingProgress);
     setDefaultVisibility(packageCacheOptions.defaultVisibility);
     setSkylarkSemantics(skylarkSemanticsOptions.toSkylarkSemantics());
-    setupDefaultPackage(defaultsPackageContents);
+    if (packageCacheOptions.experimentalInMemoryToolsDefaultsPackage) {
+      setupDefaultPackage(defaultsPackageContents);
+      PrecomputedValue.ENABLE_DEFAULTS_PACKAGE.set(injectable(), true);
+    } else {
+      setupDefaultPackage("# //tools/defaults in-memory package is not enabled.");
+      PrecomputedValue.ENABLE_DEFAULTS_PACKAGE.set(injectable(), false);
+    }
+
     setPackageLocator(pkgLocator);
 
     syscalls.set(getPerBuildSyscallCache(packageCacheOptions.globbingThreads));

src/main/java/com/google/devtools/build/lib/skyframe/packages/AbstractPackageLoader.java

@@ -279,6 +279,7 @@ public void inject(SkyKey key, SkyValue value) {
     PrecomputedValue.DEFAULT_VISIBILITY.set(injectable, ConstantRuleVisibility.PRIVATE);
     PrecomputedValue.SKYLARK_SEMANTICS.set(injectable, skylarkSemantics);
     PrecomputedValue.DEFAULTS_PACKAGE_CONTENTS.set(injectable, defaultsPackageContents);
+    PrecomputedValue.ENABLE_DEFAULTS_PACKAGE.set(injectable, true);
     return new ImmutableDiff(ImmutableList.of(), valuesToInject);
   }
 

src/test/java/com/google/devtools/build/lib/analysis/EnableDefaultsPackageOptionTest.java

@@ -0,0 +1,77 @@
+// 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.analysis;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.devtools.build.lib.analysis.util.BuildViewTestCase;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Test for experimental_enable_tools_defaults_package flag. TODO(dbabkin): remove after
+ * //tools/defaults package gone.
+ */
+@RunWith(JUnit4.class)
+public class EnableDefaultsPackageOptionTest extends BuildViewTestCase {
+
+  @Test
+  public void testEnableDefaultsPackageOptionWorks() throws Exception {
+    // do not need that as value is true by default.
+    // setPackageCacheOptions("--experimental_enable_tools_defaults_package=true");
+
+    ConfiguredTarget target = getConfiguredTarget("//tools/defaults:jdk");
+
+    assertThat(target.getLabel().toString()).isEqualTo("//tools/defaults:jdk");
+  }
+
+  @Test
+  public void testDisabledDefaultsPackageOptionWorks() throws Exception {
+
+    scratch.file(
+        "a/BUILD",
+        "filegroup(",
+        "  name = 'my_filegroup',",
+        "  srcs = ['//tools/defaults:jdk'],",
+        ")");
+
+    reporter.removeHandler(failFastHandler);
+    setPackageCacheOptions("--experimental_enable_tools_defaults_package=false");
+    ConfiguredTarget target = getConfiguredTarget("//a:my_filegroup");
+
+    assertThat(target).isNull();
+    assertContainsEvent(
+        "no such package 'tools/defaults': "
+            + "BUILD file not found on package path and referenced by '//a:my_filegroup'");
+  }
+
+  @Test
+  public void testFlipFlagOnFly() throws Exception {
+
+    setPackageCacheOptions("--experimental_enable_tools_defaults_package=false");
+    ConfiguredTarget defaultsJDKtarget = getConfiguredTarget("//tools/defaults:jdk");
+    assertThat(defaultsJDKtarget).isNull();
+
+    setPackageCacheOptions("--experimental_enable_tools_defaults_package=true");
+    defaultsJDKtarget = getConfiguredTarget("//tools/defaults:jdk");
+    assertThat(defaultsJDKtarget).isNotNull();
+    assertThat(defaultsJDKtarget.getLabel().toString()).isEqualTo("//tools/defaults:jdk");
+
+    setPackageCacheOptions("--experimental_enable_tools_defaults_package=false");
+    defaultsJDKtarget = getConfiguredTarget("//tools/defaults:jdk");
+    assertThat(defaultsJDKtarget).isNull();
+  }
+}