JMH benchmark for SimpleLruCache

See [1] for JMH documentation and [2] how to use JMH in Eclipse.

The benchmarks pom currently cannot use the JGit parent pom due to an
ecj bug [3] regarding annotation processing. Hence for now do not
inherit from the JGit parent pom and copy the compiler plugin
configuration for javac from the parent pom.

After running the Maven build the benchmark can be run using Maven:

$ java -jar org.eclipse.jgit.benchmarks/target/benchmarks.jar

or in Eclipse by running the main method of the SimpleLruCacheBenchmark
class.

[1] https://openjdk.java.net/projects/code-tools/jmh/
[2] http://alblue.bandlem.com/Page/3/index.html
[3] https://eclip.se/532029

CQ: 20517
CQ: 20518
Change-Id: Idca8a9e0980f0b8a9c741c4c9e97d03c62f07c8d
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

1 files changed, 112 insertions, 0 deletions

diff --git a/org.eclipse.jgit.benchmarks/src/org/eclipse/jgit/benchmarks/SimpleLruCacheBenchmark.java b/org.eclipse.jgit.benchmarks/src/org/eclipse/jgit/benchmarks/SimpleLruCacheBenchmark.java
new file mode 100644
index 0000000000..0f1d573af2
--- /dev/null
+++ b/org.eclipse.jgit.benchmarks/src/org/eclipse/jgit/benchmarks/SimpleLruCacheBenchmark.java
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2019, Matthias Sohn <matthias.sohn@sap.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.benchmarks;
+
+import java.security.SecureRandom;
+import java.util.concurrent.TimeUnit;
+
+import org.eclipse.jgit.util.SimpleLruCache;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Group;
+import org.openjdk.jmh.annotations.GroupThreads;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+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.runner.Runner;
+import org.openjdk.jmh.runner.RunnerException;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+@State(Scope.Benchmark)
+public class SimpleLruCacheBenchmark {
+
+	SecureRandom rnd = new SecureRandom();
+
+	private volatile SimpleLruCache<String, String> cache = new SimpleLruCache<>(
+			100, 0.2f);
+
+	private volatile int i;
+
+	@Setup
+	public void setupBenchmark() {
+		i = rnd.nextInt(250);
+	}
+
+	@TearDown
+	public void teardown() {
+		cache = null;
+	}
+
+	@Benchmark
+	@Group("readwrite")
+	@GroupThreads(1)
+	@BenchmarkMode({ Mode.AverageTime })
+	@OutputTimeUnit(TimeUnit.NANOSECONDS)
+	public SimpleLruCache<String, String> testCacheWrite() {
+		cache.put("k" + i, "v" + i);
+		return cache;
+	}
+
+	@Benchmark
+	@Group("readwrite")
+	@GroupThreads(1)
+	@BenchmarkMode({ Mode.AverageTime })
+	@OutputTimeUnit(TimeUnit.NANOSECONDS)
+	public SimpleLruCache<String, String> testCacheRead() {
+		cache.get("k" + i);
+		return cache;
+	}
+
+	public static void main(String[] args) throws RunnerException {
+		Options opt = new OptionsBuilder()
+				.include(SimpleLruCacheBenchmark.class.getSimpleName())
+				// .addProfiler(StackProfiler.class)
+				// .addProfiler(GCProfiler.class)
+				.forks(1).jvmArgs("-ea").build();
+		new Runner(opt).run();
+	}
+}