Optimize OptionalTypeCoercer unconfigured to configured coercion for …

…identity Reviewed By: gabrielrussoc shipit-source-id: 3255ca058795b1ef2f4f8a5b7b393c4dab05c325
styurin · Feb 26, 2020 · 140f565 · 140f565
1 parent 6a00645
commit 140f565
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Showing 2 changed files with 31 additions and 2 deletions.
diff --git a/src/com/facebook/buck/rules/coercer/OptionalTypeCoercer.java b/src/com/facebook/buck/rules/coercer/OptionalTypeCoercer.java
@@ -68,6 +68,11 @@ public void traverse(CellNameResolver cellRoots, Optional<T> object, Traversal t
     }
   }
 
+  @Override
+  public boolean unconfiguredToConfiguredCoercionIsIdentity() {
+    return coercer.unconfiguredToConfiguredCoercionIsIdentity();
+  }
+
   @Override
   public Optional<U> coerceToUnconfigured(
       CellNameResolver cellRoots,
@@ -82,6 +87,7 @@ public Optional<U> coerceToUnconfigured(
         coercer.coerceToUnconfigured(cellRoots, filesystem, pathRelativeToProjectRoot, object));
   }
 
+  @SuppressWarnings("unchecked")
   @Override
   public Optional<T> coerce(
       CellNameResolver cellRoots,
@@ -92,14 +98,18 @@ public Optional<T> coerce(
       Optional<U> object)
       throws CoerceFailedException {
     if (object.isPresent()) {
-      return Optional.of(
+      T coerced =
           coercer.coerce(
               cellRoots,
               filesystem,
               pathRelativeToProjectRoot,
               targetConfiguration,
               hostConfiguration,
-              object.get()));
+              object.get());
+      if (coerced == object.get()) {
+        return (Optional<T>) object;
+      }
+      return Optional.of(coerced);
     } else {
       return Optional.empty();
     }

diff --git a/test/com/facebook/buck/rules/coercer/OptionalTypeCoercerTest.java b/test/com/facebook/buck/rules/coercer/OptionalTypeCoercerTest.java
@@ -19,9 +19,11 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertThat;
 
 import com.facebook.buck.core.cell.TestCellBuilder;
+import com.facebook.buck.core.cell.nameresolver.TestCellNameResolver;
 import com.facebook.buck.core.model.UnconfiguredTargetConfiguration;
 import com.facebook.buck.core.path.ForwardRelativePath;
 import com.facebook.buck.io.filesystem.ProjectFilesystem;
@@ -133,4 +135,21 @@ public void testConcatOfPresentConcatableElementsReturnsAggregatedResult() {
                     Optional.of(ImmutableList.of("a", "c"))))
             .get());
   }
+
+  @Test
+  public void coerceUnconfiguredToConfiguredOptimizedIdentity() throws Exception {
+    OptionalTypeCoercer<String, String> coercer =
+        new OptionalTypeCoercer<>(new StringTypeCoercer());
+
+    Optional<String> input = Optional.of("aaa");
+    Optional<String> coerced =
+        coercer.coerce(
+            TestCellNameResolver.forRoot(),
+            new FakeProjectFilesystem(),
+            ForwardRelativePath.EMPTY,
+            UnconfiguredTargetConfiguration.INSTANCE,
+            UnconfiguredTargetConfiguration.INSTANCE,
+            input);
+    assertSame(input, coerced);
+  }
 }