Support --output_library_merged_assets

src/main/java/com/google/devtools/build/lib/rules/android/AndroidAssets.java

@@ -179,7 +179,14 @@ ParsedAndroidAssets parse(AndroidDataContext dataContext) throws InterruptedExce
   /** Convenience method to do all of asset processing - parsing and merging. */
   public MergedAndroidAssets process(AndroidDataContext dataContext, AssetDependencies assetDeps)
       throws InterruptedException {
-    return parse(dataContext).merge(dataContext, assetDeps);
+    ParsedAndroidAssets parsedAssets = parse(dataContext);
+
+    boolean mergeAssets = dataContext.getAndroidConfig().outputLibraryMergedAssets()
+        || dataContext.throwOnResourceConflict();
+
+    return mergeAssets ?
+        parsedAssets.merge(dataContext, assetDeps) :
+        MergedAndroidAssets.of(parsedAssets, null, assetDeps);
   }
 
   @Override

src/main/java/com/google/devtools/build/lib/rules/android/AndroidConfiguration.java

@@ -909,6 +909,14 @@ public static class Options extends FragmentOptions {
             + " instead of declarations plus all dependency references.")
     public boolean namespacedRClass;
 
+    @Option(
+            name = "output_library_merged_assets",
+            defaultValue = "true",
+            documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+            effectTags = {OptionEffectTag.UNKNOWN},
+            help = "If disabled, does not produce merged asset.zip outputs for library targets")
+    public boolean outputLibraryMergedAssets;
+
     @Option(
         name = "legacy_main_dex_list_generator",
         // TODO(b/147692286): Update this default value to R8's GenerateMainDexList binary after
@@ -1012,6 +1020,7 @@ public FragmentOptions getHost() {
   private final boolean useRTxtFromMergedResources;
   private final boolean linkLibraryResources;
   private final boolean namespacedRClass;
+  private final boolean outputLibraryMergedAssets;
   private final Label legacyMainDexListGenerator;
   private final boolean disableInstrumentationManifestMerging;
   private final boolean incompatibleUseToolchainResolution;
@@ -1072,6 +1081,7 @@ public AndroidConfiguration(BuildOptions buildOptions) throws InvalidConfigurati
     this.useRTxtFromMergedResources = options.useRTxtFromMergedResources;
     this.linkLibraryResources = options.linkLibraryResources;
     this.namespacedRClass = options.namespacedRClass;
+    this.outputLibraryMergedAssets = options.outputLibraryMergedAssets;
     this.legacyMainDexListGenerator = options.legacyMainDexListGenerator;
     this.disableInstrumentationManifestMerging = options.disableInstrumentationManifestMerging;
     this.incompatibleUseToolchainResolution = options.incompatibleUseToolchainResolution;
@@ -1349,6 +1359,10 @@ public boolean disableInstrumentationManifestMerging() {
     return disableInstrumentationManifestMerging;
   }
 
+  boolean outputLibraryMergedAssets() {
+    return outputLibraryMergedAssets;
+  }
+
   /** Returns the label provided with --legacy_main_dex_list_generator, if any. */
   // TODO(b/147692286): Move R8's main dex list tool into tool repository.
   @StarlarkConfigurationField(

src/main/java/com/google/devtools/build/lib/rules/android/MergedAndroidAssets.java

@@ -27,16 +27,16 @@ static MergedAndroidAssets mergeFrom(
       AndroidDataContext dataContext, ParsedAndroidAssets parsed, AssetDependencies deps)
       throws InterruptedException {
 
-    Artifact mergedAssets =
-        dataContext.createOutputArtifact(AndroidRuleClasses.ANDROID_ASSETS_ZIP);
+    Artifact mergedAssets = dataContext.getAndroidConfig().outputLibraryMergedAssets() ?
+        dataContext.createOutputArtifact(AndroidRuleClasses.ANDROID_ASSETS_ZIP) : null;
 
     BusyBoxActionBuilder builder = BusyBoxActionBuilder.create(dataContext, "MERGE_ASSETS");
     if (dataContext.throwOnResourceConflict()) {
       builder.addFlag("--throwOnAssetConflict");
     }
 
     builder
-        .addOutput("--assetsOutput", mergedAssets)
+        .maybeAddOutput("--assetsOutput", mergedAssets)
         .addInput(
             "--primaryData",
             AndroidDataConverter.PARSED_ASSET_CONVERTER.map(parsed),

src/tools/android/java/com/google/devtools/build/android/AndroidAssetMergingAction.java

@@ -13,9 +13,9 @@
 // limitations under the License.
 package com.google.devtools.build.android;
 
-import com.android.builder.core.VariantType;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
+import com.google.devtools.build.android.AndroidDataMerger.ContentComparingChecker;
 import com.google.devtools.build.android.Converters.PathConverter;
 import com.google.devtools.build.android.Converters.SerializedAndroidDataConverter;
 import com.google.devtools.build.android.Converters.SerializedAndroidDataListConverter;
@@ -133,30 +133,46 @@ void run(Path tmp, ExecutorServiceCloser executorService) throws Exception {
 
     Preconditions.checkNotNull(options.primary);
 
-    MergedAndroidData mergedData =
-        AndroidResourceMerger.mergeDataAndWrite(
-            options.primary,
-            /* primaryManifest = */ null,
-            options.directData,
-            options.transitiveData,
-            /* resourcesOut = */ ignored,
-            mergedAssets,
-            /* cruncher = */ null,
-            VariantType.LIBRARY,
-            /* symbolsOut = */ null,
-            /* rclassWriter = */ null,
-            options.throwOnAssetConflict,
-            executorService);
+    final ParsedAndroidData.Builder primaryBuilder = ParsedAndroidData.Builder.newBuilder();
+    final AndroidParsedDataDeserializer deserializer = AndroidParsedDataDeserializer.create();
+    options.primary.deserialize(
+        DependencyInfo.DependencyType.PRIMARY, deserializer, primaryBuilder.consumers());
+    ParsedAndroidData primaryData = primaryBuilder.build();
+
+    UnwrittenMergedAndroidData unwrittenMergedData = AndroidResourceMerger.mergeData(
+        executorService,
+        options.transitiveData,
+        options.directData,
+        primaryData,
+        /* primaryManifest = */ null,
+        /* allowPrimaryOverrideAll = */ false,
+        deserializer,
+        options.throwOnAssetConflict,
+        ContentComparingChecker.create());
 
     logCompletion("Merging");
 
-    Preconditions.checkState(
-        !Files.exists(ignored),
-        "The asset merging action should not produce non-asset merge results!");
-
-    ResourcesZip.from(ignored, mergedData.getAssetDir())
-        .writeTo(options.assetsOutput, /* compress= */ true);
-    logCompletion("Create assets zip");
+    if (options.assetsOutput != null) {
+      MergedAndroidData writtenMergedData =
+          AndroidResourceMerger.writeMergedData(
+              ignored,
+              mergedAssets,
+              /* cruncher = */ null,
+              /* symbolsOut = */ null,
+              /* rclassWriter = */ null,
+              executorService,
+              unwrittenMergedData);
+
+      logCompletion("Writing");
+
+      Preconditions.checkState(
+          !Files.exists(ignored),
+          "The asset merging action should not produce non-asset merge results!");
+
+      ResourcesZip.from(ignored, writtenMergedData.getAssetDir())
+          .writeTo(options.assetsOutput, /* compress= */ true);
+      logCompletion("Create assets zip");
+    }
   }
 
   @Override

src/tools/android/java/com/google/devtools/build/android/AndroidResourceMerger.java

@@ -86,7 +86,7 @@ static MergingException withMessage(String message) {
    * Merges all secondary resources with the primary resources, given that the primary resources
    * have not yet been parsed and serialized.
    */
-  public static MergedAndroidData mergeDataAndWrite(
+  static MergedAndroidData mergeDataAndWrite(
       final UnvalidatedAndroidData primary,
       final List<? extends SerializedAndroidData> direct,
       final List<? extends SerializedAndroidData> transitive,
@@ -99,91 +99,39 @@ public static MergedAndroidData mergeDataAndWrite(
       boolean throwOnResourceConflict) {
     try (ExecutorServiceCloser executorService = ExecutorServiceCloser.createWithFixedPoolOf(15)) {
       final ParsedAndroidData parsedPrimary = ParsedAndroidData.from(primary);
-      return mergeDataAndWrite(
-          parsedPrimary,
-          primary.getManifest(),
-          direct,
-          transitive,
+      return writeMergedData(
           resourcesOut,
           assetsOut,
           cruncher,
-          type,
           symbolsOut,
           /* rclassWriter= */ null,
-          AndroidParsedDataDeserializer.withFilteredResources(filteredResources),
-          throwOnResourceConflict,
-          executorService);
+          executorService,
+          mergeData(
+              executorService,
+              transitive,
+              direct,
+              parsedPrimary,
+              primary.getManifest(),
+              type != VariantType.LIBRARY,
+              AndroidParsedDataDeserializer.withFilteredResources(filteredResources),
+              throwOnResourceConflict,
+              ContentComparingChecker.create()));
     } catch (IOException e) {
       throw MergingException.wrapException(e);
     }
   }
 
-  /**
-   * Merges all secondary resources with the primary resources, given that the primary resources
-   * have been separately parsed and serialized.
-   */
-  public static MergedAndroidData mergeDataAndWrite(
-      final SerializedAndroidData primary,
-      final Path primaryManifest,
-      final List<? extends SerializedAndroidData> direct,
-      final List<? extends SerializedAndroidData> transitive,
+  /** Writes out merged data. */
+  static MergedAndroidData writeMergedData(
       final Path resourcesOut,
       final Path assetsOut,
       @Nullable final PngCruncher cruncher,
-      final VariantType type,
-      @Nullable final Path symbolsOut,
-      @Nullable final AndroidResourceClassWriter rclassWriter,
-      boolean throwOnResourceConflict,
-      ListeningExecutorService executorService) {
-    final ParsedAndroidData.Builder primaryBuilder = ParsedAndroidData.Builder.newBuilder();
-    final AndroidParsedDataDeserializer deserializer = AndroidParsedDataDeserializer.create();
-    primary.deserialize(
-        DependencyInfo.DependencyType.PRIMARY, deserializer, primaryBuilder.consumers());
-    ParsedAndroidData primaryData = primaryBuilder.build();
-    return mergeDataAndWrite(
-        primaryData,
-        primaryManifest,
-        direct,
-        transitive,
-        resourcesOut,
-        assetsOut,
-        cruncher,
-        type,
-        symbolsOut,
-        rclassWriter,
-        deserializer,
-        throwOnResourceConflict,
-        executorService);
-  }
-
-  /** Merges all secondary resources with the primary resources. */
-  private static MergedAndroidData mergeDataAndWrite(
-      final ParsedAndroidData primary,
-      final Path primaryManifest,
-      final List<? extends SerializedAndroidData> direct,
-      final List<? extends SerializedAndroidData> transitive,
-      final Path resourcesOut,
-      final Path assetsOut,
-      @Nullable final PngCruncher cruncher,
-      final VariantType type,
       @Nullable final Path symbolsOut,
       @Nullable AndroidResourceClassWriter rclassWriter,
-      AndroidParsedDataDeserializer deserializer,
-      boolean throwOnResourceConflict,
-      ListeningExecutorService executorService) {
+      ListeningExecutorService executorService,
+      UnwrittenMergedAndroidData merged) {
     Stopwatch timer = Stopwatch.createStarted();
     try {
-      UnwrittenMergedAndroidData merged =
-          mergeData(
-              executorService,
-              transitive,
-              direct,
-              primary,
-              primaryManifest,
-              type != VariantType.LIBRARY,
-              deserializer,
-              throwOnResourceConflict,
-              ContentComparingChecker.create());
       timer.reset().start();
       if (symbolsOut != null) {
         AndroidDataSerializer serializer = AndroidDataSerializer.create();
@@ -212,7 +160,7 @@ private static MergedAndroidData mergeDataAndWrite(
     }
   }
 
-  private static UnwrittenMergedAndroidData mergeData(
+  static UnwrittenMergedAndroidData mergeData(
       ListeningExecutorService executorService,
       List<? extends SerializedAndroidData> transitive,
       List<? extends SerializedAndroidData> direct,