From 5b0af1a80bb4d2a81cda7e26a6ad0db43e679519 Mon Sep 17 00:00:00 2001
From: Alan Bateman <alanb@openjdk.org>
Date: Thu, 19 Jan 2023 06:59:38 +0000
Subject: [PATCH] 8208077: File.listRoots performance degradation

Reviewed-by: lancea, bpb
---
 .../classes/java/io/WinNTFileSystem.java      |  4 +--
 test/jdk/java/io/File/ListRoots.java          | 36 +++++++++++++------
 2 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/src/java.base/windows/classes/java/io/WinNTFileSystem.java b/src/java.base/windows/classes/java/io/WinNTFileSystem.java
index 6369759da74..6da8dfa7b4f 100644
--- a/src/java.base/windows/classes/java/io/WinNTFileSystem.java
+++ b/src/java.base/windows/classes/java/io/WinNTFileSystem.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2023, 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
@@ -745,7 +745,7 @@ class WinNTFileSystem extends FileSystem {
             .valueOf(new long[] {listRoots0()})
             .stream()
             .mapToObj(i -> new File((char)('A' + i) + ":" + slash))
-            .filter(f -> access(f.getPath()) && f.exists())
+            .filter(f -> access(f.getPath()))
             .toArray(File[]::new);
     }
     private static native int listRoots0();
diff --git a/test/jdk/java/io/File/ListRoots.java b/test/jdk/java/io/File/ListRoots.java
index 51dd1913bd1..7b14b2f3b08 100644
--- a/test/jdk/java/io/File/ListRoots.java
+++ b/test/jdk/java/io/File/ListRoots.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2023, 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
@@ -23,11 +23,17 @@
 
 /* @test
    @bug 4071322
-   @summary Basic test for listRoots method
+   @summary Basic test for File.listRoots method
  */
 
-import java.io.*;
-
+import java.io.File;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
 
 public class ListRoots {
 
@@ -37,15 +43,25 @@ public class ListRoots {
             System.out.println(i + ": " + rs[i]);
         }
 
-        File f = new File(System.getProperty("test.src", "."),
-                          "ListRoots.java");
+        File f = new File(System.getProperty("test.src", "."), "ListRoots.java");
         String cp = f.getCanonicalPath();
-        for (int i = 0; i < rs.length; i++) {
-            if (cp.startsWith(rs[i].getPath())) break;
-            if (i == rs.length - 1)
-                throw new Exception(cp + " does not have a recognized root");
+        boolean found = Stream.of(rs)
+                .map(File::getPath)
+                .anyMatch(p -> cp.startsWith(p));
+        if (!found) {
+            throw new RuntimeException(cp + " does not have a recognized root");
         }
 
+        // the list of roots should match FileSystem::getRootDirectories
+        Set<File> roots1 = Stream.of(rs).collect(Collectors.toSet());
+        FileSystem fs = FileSystems.getDefault();
+        Set<File> roots2 = StreamSupport.stream(fs.getRootDirectories().spliterator(), false)
+                .map(Path::toFile)
+                .collect(Collectors.toSet());
+        if (!roots1.equals(roots2)) {
+            System.out.println(roots2);
+            throw new RuntimeException("Does not match FileSystem::getRootDirectories");
+        }
     }
 
 }