8380467: JFR: RepositoryFiles.updatePaths() searches for chunkfiles incorrectly

Reviewed-by: egahlin

src/jdk.jfr/share/classes/jdk/jfr/internal/consumer/RepositoryFiles.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2026, 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
@@ -181,9 +181,9 @@ public final class RepositoryFiles {
             List<Path> added = new ArrayList<>();
             Set<Path> current = new HashSet<>();
             for (Path p : dirStream) {
-                if (!pathLookup.containsKey(p)) {
-                    String s = p.toString();
-                    if (s.endsWith(".jfr")) {
+                String s = p.toString();
+                if (s.endsWith(".jfr")) {
+                    if (!pathLookup.containsKey(p)) {
                         added.add(p);
                         Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG, "New file found: " + p.toAbsolutePath());
                     }

test/jdk/jdk/jfr/api/consumer/streaming/TestRepositoryFilesRescan.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2026, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.jfr.api.consumer.streaming;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import jdk.jfr.Recording;
+import jdk.jfr.internal.consumer.RepositoryFiles;
+import jdk.test.lib.Asserts;
+
+/**
+ * @test
+ * @summary Verifies that RepositoryFiles does not oscillate between
+ *          forgetting and rediscovering chunk files between scans
+ * @requires vm.hasJFR
+ * @library /test/lib
+ * @modules jdk.jfr/jdk.jfr.internal.consumer
+ * @run main/othervm jdk.jfr.api.consumer.streaming.TestRepositoryFilesRescan
+ */
+public class TestRepositoryFilesRescan {
+
+    public static void main(String... args) throws Exception {
+        Path dir = Files.createTempDirectory("jfr-rescan-test");
+        try {
+            createChunkFile(dir, "chunk1.jfr");
+            createChunkFile(dir, "chunk2.jfr");
+            testNoOscillation(dir);
+        } finally {
+            deleteDirectory(dir);
+        }
+    }
+
+    /**
+     * firstPath(0, false) will return non-null only when updatePaths discovers
+     * genuinely new chunk files; with no files added or removed between
+     * calls the result must be null after the first successful call.
+     */
+    private static void testNoOscillation(Path dir) {
+        RepositoryFiles rf = new RepositoryFiles(dir, false);
+        Asserts.assertNotNull(rf.firstPath(0, false), "Call 1: expected non-null (initial discovery of .jfr files)");
+
+        Path p2 = rf.firstPath(0, false);
+        Asserts.assertNull(p2, "Call 2: expected null (no new chunks), got " + p2);
+
+        // Call 3: still no new files.  This confirms call 2 did not wipe pathLookup, making all files look "new" again.
+        Path p3 = rf.firstPath(0, false);
+        Asserts.assertNull(p3, "Call 3: expected null (no new chunks), got " + p3
+            + " — pathLookup is oscillating between populated and empty");
+    }
+
+    private static void createChunkFile(Path dir, String name) throws Exception {
+        try (Recording r = new Recording()) {
+            r.start();
+            Thread.sleep(20);
+            r.stop();
+            r.dump(dir.resolve(name));
+        }
+    }
+
+    private static void deleteDirectory(Path dir) {
+        try {
+            try (var stream = Files.list(dir)) {
+                stream.forEach(p -> {
+                    try {
+                        Files.deleteIfExists(p);
+                    } catch (Exception e) {
+                        // Do nothing
+                    }
+                });
+            }
+            Files.deleteIfExists(dir);
+        } catch (Exception e) {
+            // best-effort cleanup
+        }
+    }
+}