Getting App Size per module using Bundletool

bundletool.diff

diff --git a/src/main/java/com/android/tools/build/bundletool/commands/GetSizeCommand.java b/src/main/java/com/android/tools/build/bundletool/commands/GetSizeCommand.java
index 80ca234..438bb5b 100755
--- a/src/main/java/com/android/tools/build/bundletool/commands/GetSizeCommand.java
+++ b/src/main/java/com/android/tools/build/bundletool/commands/GetSizeCommand.java
@@ -96,6 +96,7 @@ public abstract class GetSizeCommand implements GetSizeRequest {
   private static final Flag<Path> DEVICE_SPEC_FLAG = Flag.path("device-spec");
   private static final Flag<ImmutableSet<String>> MODULES_FLAG = Flag.stringSet("modules");
   private static final Flag<Boolean> INSTANT_FLAG = Flag.booleanFlag("instant");
+  private static final Flag<Boolean> EXACT_FLAG = Flag.booleanFlag("exact");
   private static final Flag<ImmutableSet<Dimension>> DIMENSIONS_FLAG =
       Flag.enumSet("dimensions", Dimension.class);
   private static final Joiner COMMA_JOINER = Joiner.on(',');
@@ -121,10 +122,15 @@ public abstract class GetSizeCommand implements GetSizeRequest {
   @Override
   public abstract boolean getInstant();
 
+  /** Gets whether only explicit modules should used for size calculation */
+  @Override
+  public abstract boolean getExact();
+
   public static Builder builder() {
     return new AutoValue_GetSizeCommand.Builder()
         .setDeviceSpec(DeviceSpec.getDefaultInstance())
         .setInstant(false)
+        .setExact(false)
         .setDimensions(ImmutableSet.of());
   }
 
@@ -151,6 +157,14 @@ public abstract class GetSizeCommand implements GetSizeRequest {
      */
     public abstract Builder setInstant(boolean instant);
 
+    /**
+     * Sets whether to only use modules explicitly specified in app size calculation
+     *
+     * <p>The default is {@code false}. If this is set to {@code true}, only the modules
+     * specified by modules flag be used in size calculation
+     */
+    public abstract Builder setExact(boolean exact);
+
     /** Sets the sub-command of the get-size command, e.g. total. */
     public abstract Builder setGetSizeSubCommand(GetSizeSubcommand getSizeSubcommand);
 
@@ -162,6 +176,7 @@ public abstract class GetSizeCommand implements GetSizeRequest {
     Optional<Path> deviceSpecPath = DEVICE_SPEC_FLAG.getValue(flags);
     Optional<ImmutableSet<String>> modules = MODULES_FLAG.getValue(flags);
     Optional<Boolean> instant = INSTANT_FLAG.getValue(flags);
+    Optional<Boolean> exact = EXACT_FLAG.getValue(flags);
 
     ImmutableSet<Dimension> dimensions = DIMENSIONS_FLAG.getValue(flags).orElse(ImmutableSet.of());
     flags.checkNoUnknownFlags();
@@ -183,6 +198,8 @@ public abstract class GetSizeCommand implements GetSizeRequest {
 
     instant.ifPresent(command::setInstant);
 
+    exact.ifPresent(command::setExact);
+
     if (dimensions.contains(Dimension.ALL)) {
       dimensions = SUPPORTED_DIMENSIONS;
     }
@@ -305,6 +322,14 @@ public abstract class GetSizeCommand implements GetSizeRequest {
                     "When set, APKs of the instant modules will be considered instead of the "
                         + "installable APKs. Defaults to false.")
                 .build())
+        .addFlag(
+                FlagDescription.builder()
+                    .setFlagName(EXACT_FLAG.getName())
+                    .setOptional(true)
+                    .setDescription(
+                            "When set, only APKs with modules explicitly defined will" +
+                                    "be considered for size calculation. Defaults to false.")
+                    .build())
         .build();
   }
 
diff --git a/src/main/java/com/android/tools/build/bundletool/device/ApkMatcher.java b/src/main/java/com/android/tools/build/bundletool/device/ApkMatcher.java
index aa7c58a..afc83f8 100755
--- a/src/main/java/com/android/tools/build/bundletool/device/ApkMatcher.java
+++ b/src/main/java/com/android/tools/build/bundletool/device/ApkMatcher.java
@@ -54,8 +54,21 @@ public class ApkMatcher {
   private final ModuleMatcher moduleMatcher;
   private final VariantMatcher variantMatcher;
 
+  /**
+   * Only include modules explicitly specified by requestedModuleNames
+   */
+  private final boolean exact;
+
   public ApkMatcher(DeviceSpec deviceSpec) {
-    this(deviceSpec, Optional.empty(), /* matchInstant= */ false);
+    this(deviceSpec, Optional.empty(), /* matchInstant= */ false, false);
+  }
+
+  public ApkMatcher(
+          DeviceSpec deviceSpec,
+          Optional<ImmutableSet<String>> requestedModuleNames,
+          boolean matchInstant
+  ) {
+      this(deviceSpec, requestedModuleNames, matchInstant, false);
   }
 
   /**
@@ -65,10 +78,14 @@ public class ApkMatcher {
   public ApkMatcher(
       DeviceSpec deviceSpec,
       Optional<ImmutableSet<String>> requestedModuleNames,
-      boolean matchInstant) {
+      boolean matchInstant,
+      boolean exact) {
     checkArgument(
         !requestedModuleNames.isPresent() || !requestedModuleNames.get().isEmpty(),
         "Set of requested split modules cannot be empty.");
+    checkArgument(
+            !exact || requestedModuleNames.isPresent(),
+            "Exact mode requires providing one or more module names");
     SdkVersionMatcher sdkVersionMatcher = new SdkVersionMatcher(deviceSpec);
     AbiMatcher abiMatcher = new AbiMatcher(deviceSpec);
     MultiAbiMatcher multiAbiMatcher = new MultiAbiMatcher(deviceSpec);
@@ -81,6 +98,7 @@ public class ApkMatcher {
             sdkVersionMatcher, abiMatcher, multiAbiMatcher, screenDensityMatcher, languageMatcher);
     this.requestedModuleNames = requestedModuleNames;
     this.matchInstant = matchInstant;
+    this.exact = exact;
     this.moduleMatcher = new ModuleMatcher(sdkVersionMatcher, deviceFeatureMatcher);
     this.variantMatcher =
         new VariantMatcher(
@@ -137,7 +155,9 @@ public class ApkMatcher {
         addModuleDependencies(requestedModuleName, moduleDependenciesMap, dependencyModules);
       }
 
-      if (matchInstant) {
+      if (exact) {
+        return requestedModuleNames.get()::contains;
+      } else if (matchInstant) {
         return dependencyModules::contains;
       } else {
         return Predicates.or(
diff --git a/src/main/java/com/android/tools/build/bundletool/device/VariantTotalSizeAggregator.java b/src/main/java/com/android/tools/build/bundletool/device/VariantTotalSizeAggregator.java
index a68dfb4..c6d5df6 100755
--- a/src/main/java/com/android/tools/build/bundletool/device/VariantTotalSizeAggregator.java
+++ b/src/main/java/com/android/tools/build/bundletool/device/VariantTotalSizeAggregator.java
@@ -224,7 +224,8 @@ public class VariantTotalSizeAggregator {
                               screenDensityTargeting,
                               languageTargeting),
                           getSizeRequest.getModules(),
-                          getSizeRequest.getInstant())
+                          getSizeRequest.getInstant(),
+                          getSizeRequest.getExact())
                       .getMatchingApksFromVariant(variant, bundleVersion));
 
           minSizeByConfiguration.merge(configuration, compressedSize, Math::min);
diff --git a/src/main/java/com/android/tools/build/bundletool/model/GetSizeRequest.java b/src/main/java/com/android/tools/build/bundletool/model/GetSizeRequest.java
index 7567ce4..fc7a493 100755
--- a/src/main/java/com/android/tools/build/bundletool/model/GetSizeRequest.java
+++ b/src/main/java/com/android/tools/build/bundletool/model/GetSizeRequest.java
@@ -40,4 +40,7 @@ public interface GetSizeRequest {
 
   /** Gets whether instant APKs should be used for size calculation. */
   boolean getInstant();
+
+  /** Gets whether only explicit modules should used for size calculation */
+  boolean getExact();
 }

With this patch, it is now possible to request app size for specific module(s) using the --exact flag:
bundletool get-size total --apks=output.apks --modules=my_feature --exact --dimensions=ALL