add benchmark for the annotation overlay

The benchmark is rather simplistic and cannot be used in isolation.
A real-world benchmark needs to be used as well.

benchmarks/run-benchmarks.sh

@@ -4,7 +4,7 @@ VERSIONS="HEAD"
 BENCHMARKS=".*"
 
 help() {
-  echo "Usage: run-benchmarks.sh [--versions <versions>] [--benchmars <benchmarks>] [--help]"
+  echo "Usage: run-benchmarks.sh [--versions <versions>] [--benchmarks <benchmarks>] [--help]"
   echo
   echo "  --versions <versions>: comma-separated list of Jandex versions (Git commits) to benchmark"
   echo "                         defaults to 'HEAD'"

benchmarks/src/main/java/org/jboss/jandex/chart/ChartGenerator.java

@@ -64,7 +64,7 @@ public static void main(String[] args) throws IOException {
                     .build();
             chart.getStyler()
                     .setXAxisTicksVisible(true)
-                    .setXAxisLabelRotation(90);
+                    .setXAxisLabelRotation(45);
 
             for (BenchmarksForVersion benchmarksForVersion : allVersions) {
                 List<String> names = new ArrayList<>();

benchmarks/src/test/java/org/jboss/jandex/AnnotationOverlayBenchmark.java

@@ -0,0 +1,193 @@
+package org.jboss.jandex;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+@BenchmarkMode(Mode.Throughput)
+@Fork(5)
+@Warmup(iterations = 5, time = 1, batchSize = 8192)
+@Measurement(iterations = 5, time = 1, batchSize = 8192)
+@State(Scope.Benchmark)
+public class AnnotationOverlayBenchmark {
+    private Index index;
+    private AnnotationOverlay overlay;
+
+    @Setup
+    public void setup() throws IOException {
+        index = Index.of(MyAnn1.class, MyAnn2.class, MyClass1.class, MyClass2.class, MyClass3.class,
+                MyClass4.class, MyClass5.class, MyClass6.class, MyClass7.class, MyClass8.class, MyClass9.class);
+
+        AnnotationTransformation transformation = new AnnotationTransformation() {
+            @Override
+            public boolean supports(AnnotationTarget.Kind kind) {
+                return kind == AnnotationTarget.Kind.CLASS;
+            }
+
+            @Override
+            public void apply(TransformationContext context) {
+                String name = context.declaration().asClass().name().toString();
+                if (name.endsWith("2") || name.endsWith("4")) {
+                    context.removeAll();
+                } else if (name.endsWith("6") || name.endsWith("8")) {
+                    context.add(MyAnn2.class);
+                }
+            }
+        };
+        overlay = AnnotationOverlay.builder(index, Collections.singleton(transformation)).build();
+    }
+
+    @Benchmark
+    public List<AnnotationInstance> noTransformation() {
+        List<AnnotationInstance> result = new ArrayList<>(5);
+
+        ClassInfo clazz = index.getClassByName(MyClass1.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass3.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass5.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass7.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass9.class);
+        result.addAll(overlay.annotations(clazz));
+
+        return result;
+    }
+
+    @Benchmark
+    public List<AnnotationInstance> removedAnnotations() {
+        List<AnnotationInstance> result = new ArrayList<>(0);
+
+        ClassInfo clazz = index.getClassByName(MyClass2.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass4.class);
+        result.addAll(overlay.annotations(clazz));
+
+        return result;
+    }
+
+    @Benchmark
+    public List<AnnotationInstance> addedAnnotations() {
+        List<AnnotationInstance> result = new ArrayList<>(4);
+
+        ClassInfo clazz = index.getClassByName(MyClass6.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass8.class);
+        result.addAll(overlay.annotations(clazz));
+
+        return result;
+    }
+
+    @Benchmark
+    public List<AnnotationInstance> addedAndRemovedAnnotations() {
+        List<AnnotationInstance> result = new ArrayList<>(4);
+
+        ClassInfo clazz = index.getClassByName(MyClass2.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass4.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass6.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass8.class);
+        result.addAll(overlay.annotations(clazz));
+
+        return result;
+    }
+
+    @Benchmark
+    public List<AnnotationInstance> allClasses() {
+        List<AnnotationInstance> result = new ArrayList<>(9);
+
+        ClassInfo clazz = index.getClassByName(MyClass1.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass2.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass3.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass4.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass5.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass6.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass7.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass8.class);
+        result.addAll(overlay.annotations(clazz));
+
+        clazz = index.getClassByName(MyClass9.class);
+        result.addAll(overlay.annotations(clazz));
+
+        return result;
+    }
+
+    public @interface MyAnn1 {
+    }
+
+    public @interface MyAnn2 {
+    }
+
+    @MyAnn1
+    public static class MyClass1 {
+    }
+
+    @MyAnn1
+    public static class MyClass2 {
+    }
+
+    @MyAnn1
+    public static class MyClass3 {
+    }
+
+    @MyAnn1
+    public static class MyClass4 {
+    }
+
+    @MyAnn1
+    public static class MyClass5 {
+    }
+
+    @MyAnn1
+    public static class MyClass6 {
+    }
+
+    @MyAnn1
+    public static class MyClass7 {
+    }
+
+    @MyAnn1
+    public static class MyClass8 {
+    }
+
+    @MyAnn1
+    public static class MyClass9 {
+    }
+}