Add benchmark for unified function

Signed-off-by: Chen Dai <daichen@amazon.com>

Author: dai-chen

benchmarks/build.gradle

@@ -5,6 +5,8 @@
 
 plugins {
     id 'java-library'
+    id "io.freefair.lombok"
+    id 'com.diffplug.spotless'
     id "me.champeau.jmh" version "0.7.3"
 }
 
@@ -27,8 +29,17 @@ spotless {
     java {
         target fileTree('.') {
             include '**/*.java'
-            exclude '**/jmh_generated/**'
+            exclude '**/jmh_generated/**', '**/build/**'
         }
+        importOrder()
+        licenseHeader("/*\n" +
+                " * Copyright OpenSearch Contributors\n" +
+                " * SPDX-License-Identifier: Apache-2.0\n" +
+                " */\n\n")
+        removeUnusedImports()
+        trimTrailingWhitespace()
+        endWithNewline()
+        googleJavaFormat('1.32.0').reflowLongStrings().groupArtifact('com.google.googlejavaformat:google-java-format')
     }
 }
 

benchmarks/src/jmh/java/org/opensearch/sql/api/UnifiedFunctionBenchmark.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.api;
+
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import lombok.RequiredArgsConstructor;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OperationsPerInvocation;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.TearDown;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+import org.opensearch.sql.api.function.UnifiedFunction;
+import org.opensearch.sql.api.function.UnifiedFunctionRepository;
+
+/**
+ * JMH benchmark for measuring {@link UnifiedFunction} performance. Tests one representative
+ * function per PPL category (json, math, conditional, collection, string).
+ *
+ * <p>Benchmarks:
+ *
+ * <ul>
+ *   <li>{@link #loadFunction()}: Measures function loading from repository
+ *   <li>{@link #evalFunction(Blackhole)}: Measures function evaluation (1000 calls per invocation)
+ * </ul>
+ */
+@Warmup(iterations = 2, time = 1)
+@Measurement(iterations = 5, time = 1)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@State(Scope.Thread)
+@Fork(value = 1)
+public class UnifiedFunctionBenchmark extends UnifiedQueryTestBase {
+
+  private static final int OPS = 1000;
+
+  @Param public BenchmarkCase benchmarkCase;
+
+  private UnifiedFunctionRepository repository;
+  private UnifiedFunction function;
+  private List<Object> inputs;
+
+  @Setup(Level.Trial)
+  public void setUpBenchmark() {
+    super.setUp();
+
+    repository = new UnifiedFunctionRepository(context);
+    function = benchmarkCase.loadFunction(repository);
+    inputs = benchmarkCase.inputs();
+  }
+
+  @TearDown(Level.Trial)
+  public void tearDownBenchmark() throws Exception {
+    super.tearDown();
+  }
+
+  /** Benchmarks function loading from repository. */
+  @Benchmark
+  public UnifiedFunction loadFunction() {
+    return benchmarkCase.loadFunction(repository);
+  }
+
+  /** Benchmarks function evaluation with pre-loaded function and inputs. */
+  @Benchmark
+  @OperationsPerInvocation(OPS)
+  public void evalFunction(Blackhole bh) {
+    for (int i = 0; i < OPS; i++) {
+      bh.consume(function.eval(inputs));
+    }
+  }
+
+  /** Enum defining benchmark test cases - one representative function per PPL category. */
+  @RequiredArgsConstructor
+  public enum BenchmarkCase {
+    JSON_EXTRACT(
+        List.of("VARCHAR", "VARCHAR"), List.of("{\"name\":\"test\",\"value\":42}", "$.name")),
+    MOD(List.of("INTEGER", "INTEGER"), List.of(17, 5)),
+    COALESCE(List.of("VARCHAR", "VARCHAR"), List.of("first_value", "default_value")),
+    ARRAY(List.of("INTEGER", "INTEGER", "INTEGER"), List.of(1, 2, 3)),
+    SHA2(List.of("VARCHAR", "INTEGER"), List.of("hello world", 256));
+
+    private final List<String> inputTypes;
+    private final List<Object> inputs;
+
+    UnifiedFunction loadFunction(UnifiedFunctionRepository repository) {
+      return repository
+          .loadFunction(name())
+          .map(desc -> desc.getBuilder().build(inputTypes))
+          .orElseThrow();
+    }
+
+    List<Object> inputs() {
+      return inputs;
+    }
+  }
+}

benchmarks/src/jmh/java/org/opensearch/sql/api/UnifiedQueryBenchmark.java

@@ -50,7 +50,7 @@
 @Warmup(iterations = 2, time = 1)
 @Measurement(iterations = 5, time = 1)
 @BenchmarkMode(Mode.AverageTime)
-@OutputTimeUnit(TimeUnit.MICROSECONDS)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
 @State(Scope.Thread)
 @Fork(value = 1)
 public class UnifiedQueryBenchmark extends UnifiedQueryTestBase {