Fold ToPath into FileOpen, add root benchmarks to keep mix comparable

test/micro/org/openjdk/bench/java/io/FileOpen.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -28,23 +28,24 @@
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.concurrent.TimeUnit;
 
 /**
  * Tests the overheads of I/O API.
  */
 @BenchmarkMode(Mode.AverageTime)
-@OutputTimeUnit(TimeUnit.MICROSECONDS)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
 @State(Scope.Thread)
 @Warmup(time=2, iterations=5)
 @Measurement(time=3, iterations=5)
 @Fork(value=2, jvmArgs="-Xmx1g")
 public class FileOpen {
 
-    public String normalFile = "/test/dir/file/name.txt";
-    public String root = "/";
-    public String trailingSlash = "/test/dir/file/name.txt/";
-    public String notNormalizedFile = "/test/dir/file//name.txt";
+    private String normalFile = "/test/dir/file/name.txt";
+    private String root = "/";
+    private String trailingSlash = "/test/dir/file/name.txt/";
+    private String notNormalizedFile = "/test/dir/file//name.txt";
 
     public File tmp;
 
@@ -68,6 +69,11 @@ public File normalized() {
         return new File(normalFile);
     }
 
+    @Benchmark
+    public File root() {
+        return new File(root);
+    }
+
     @Benchmark
     public File trailingSlash() {
         return new File(trailingSlash);
@@ -85,4 +91,48 @@ public boolean booleanAttributes() {
                 && tmp.isDirectory()
                 && tmp.isFile();
     }
+
+    /**
+     * Examine overheads of converting Files to Paths
+     */
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    @State(Scope.Thread)
+    @Warmup(time=2, iterations=5)
+    @Measurement(time=3, iterations=5)
+    @Fork(value=2, jvmArgs="-Xmx1g")
+    public static class ToPath {
+        private String normalFile = "/test/dir/file/name.txt";
+        private String root = "/";
+        private String trailingSlash = "/test/dir/file/name.txt/";
+        private String notNormalizedFile = "/test/dir/file//name.txt";
+
+        @Benchmark
+        public void mix(Blackhole bh)  {
+            bh.consume(new File(normalFile).toPath());
+            bh.consume(new File(root).toPath());
+            bh.consume(new File(trailingSlash).toPath());
+            bh.consume(new File(notNormalizedFile).toPath());
+        }
+
+        @Benchmark
+        public Path normalized() {
+            return new File(normalFile).toPath();
+        }
+
+        @Benchmark
+        public File root() {
+            return new File(root);
+        }
+
+        @Benchmark
+        public Path trailingSlash() {
+            return new File(trailingSlash).toPath();
+        }
+
+        @Benchmark
+        public Path notNormalized() {
+            return new File(notNormalizedFile).toPath();
+        }
+    }
 }