benchmark instructions upgrade for gradle (#188)

* benchmark instructions upgrade for gradle

* changelog entry

Author: isaacbrodsky

CHANGELOG.md

@@ -5,6 +5,10 @@ The public API of this library consists of the public functions declared in
 file [H3Core.java](./src/main/java/com/uber/h3core/H3Core.java), and support
 for the Linux x64 and Darwin x64 platforms.
 
+## Unreleased Changes
+### Changed
+- Restored benchmark target to the build script. (#188)
+
 ## [4.3.2] - 2025-10-10
 ### Changed
 - Added option to build and publish as an Android module into h3-android. (#184)

README.md

@@ -90,13 +90,10 @@ Then open the file `build/docs/javadoc/index.html`.
 
 ## Benchmarking
 
-To run benchmarks, either execute them from IntelliJ or run the following from shell: (Replace the class name as needed)
-
-> [!TIP]  
-> These instructions need to be updated for Gradle.
+To run benchmarks, either execute them from IntelliJ or run the following from shell:
 
 ```sh
-mvn exec:exec -Dexec.executable="java" -Dexec.args="-classpath %classpath com.uber.h3core.benchmarking.H3CoreBenchmark" -Dexec.classpathScope="test"
+./gradlew benchmark -Ph3UseDocker=false
 ```
 
 ## Contributing

build.gradle

@@ -37,8 +37,8 @@ repositories {
 }
 
 dependencies {
-    testImplementation 'org.openjdk.jmh:jmh-core:1.19'
-    testAnnotationProcessor 'org.openjdk.jmh:jmh-generator-annprocess:1.19'
+    testImplementation 'org.openjdk.jmh:jmh-core:1.37'
+    testAnnotationProcessor 'org.openjdk.jmh:jmh-generator-annprocess:1.37'
     testImplementation 'com.google.guava:guava:33.3.1-jre'
     testImplementation 'org.junit.jupiter:junit-jupiter:5.11.2'
     testRuntimeOnly 'org.junit.platform:junit-platform-launcher:1.11.2'
@@ -101,6 +101,26 @@ processResources {
     dependsOn buildH3
 }
 
+def benchmarkClasses = [
+    'benchmarkH3Core': 'H3CoreBenchmark',
+    'benchmarkGridDisk': 'GridDiskBenchmark',
+    'benchmarkH3ParentChild': 'H3ParentChildBenchmark',
+    'benchmarkCellsToMultipolygon': 'CellsToMultiPolygonBenchmark',
+    'benchmarkPolygonToCells': 'PolygonToCellsBenchmark'
+]
+
+benchmarkClasses.each { taskName, className ->
+    tasks.register(taskName, JavaExec) {
+        dependsOn processResources
+        mainClass = "com.uber.h3core.benchmarking.${className}"
+        classpath = sourceSets.test.runtimeClasspath
+    }
+}
+
+task benchmark {
+    dependsOn benchmarkClasses.keySet()
+}
+
 test {
     dependsOn processResources
     // finalizedBy jacocoTestReport