Benchmark for creating files and FileSnapshots

Change-Id: I953fd8b6b9743b0b9cada244331253eb2121784d
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.benchmarks/src/org/eclipse/jgit/benchmarks/CreateFileSnapshotBenchmark.java

@@ -0,0 +1,111 @@
+/*
+ * 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.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+
+import org.eclipse.jgit.internal.storage.file.FileSnapshot;
+import org.eclipse.jgit.util.FileUtils;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Measurement;
+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.annotations.Warmup;
+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.Thread)
+public class CreateFileSnapshotBenchmark {
+
+	Path path;
+
+	Path testDir;
+
+	@Setup
+	public void setupBenchmark() throws IOException {
+		testDir = Files.createTempDirectory("dir");
+		path = testDir.resolve("toSnapshot");
+		Files.createFile(path);
+	}
+
+	@TearDown
+	public void teardown() throws IOException {
+		FileUtils.delete(testDir.toFile(), FileUtils.RECURSIVE | FileUtils.RETRY);
+	}
+
+	@Benchmark
+	@BenchmarkMode({ Mode.AverageTime })
+	@OutputTimeUnit(TimeUnit.NANOSECONDS)
+    @Warmup(iterations = 5, time = 100, timeUnit = TimeUnit.MILLISECONDS)
+    @Measurement(iterations = 5, time = 100, timeUnit = TimeUnit.MILLISECONDS)
+	public Path testCreateFile() throws IOException {
+		return Files.createTempFile(testDir, "create", "");
+	}
+
+	@Benchmark
+	@BenchmarkMode({ Mode.AverageTime })
+	@OutputTimeUnit(TimeUnit.NANOSECONDS)
+	public FileSnapshot testCreateFileSnapshot() {
+		return FileSnapshot.save(path.toFile());
+	}
+
+	public static void main(String[] args) throws RunnerException {
+		Options opt = new OptionsBuilder()
+				.include(CreateFileSnapshotBenchmark.class.getSimpleName())
+				// .addProfiler(StackProfiler.class)
+				// .addProfiler(GCProfiler.class)
+				.forks(1).jvmArgs("-ea").build();
+		new Runner(opt).run();
+	}
+}