8294151: JFR: Unclear exception message when dumping stopped in memor…

…y recording

Reviewed-by: mgronlun

src/jdk.jfr/share/classes/jdk/jfr/Recording.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2022, 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
@@ -348,7 +348,7 @@ public void close() {
 
     /**
      * Returns a clone of this recording, with a new recording ID and name.
-     *
+     * <p>
      * Clones are useful for dumping data without stopping the recording. After
      * a clone is created, the amount of data to copy is constrained
      * with the {@link #setMaxAge(Duration)} method and the {@link #setMaxSize(long)}method.
@@ -364,21 +364,26 @@ public Recording copy(boolean stop) {
     /**
      * Writes recording data to a file.
      * <p>
-     * Recording must be started, but not necessarily stopped.
+     * For a dump to succeed, the recording must either be 1) running, or 2) stopped
+     * and to disk. If the recording is in any other state, an
+     * {@link IOException} is thrown.
      *
      * @param destination the location where recording data is written, not
      *        {@code null}
      *
-     * @throws IOException if the recording can't be copied to the specified
-     *         location
+     * @throws IOException if recording data can't be copied to the specified
+     *         location, for example, if the recording is closed or the
+     *         destination path is not writable
      *
      * @throws SecurityException if a security manager exists and the caller doesn't
      *         have {@code FilePermission} to write to the destination path
+     *
+     * @see #getState()
+     * @see #isToDisk()
      */
     public void dump(Path destination) throws IOException {
         Objects.requireNonNull(destination, "destination");
         internal.dump(new WriteableUserPath(destination));
-
     }
 
     /**

src/jdk.jfr/share/classes/jdk/jfr/internal/PlatformRecording.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2022, 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
@@ -321,7 +321,12 @@ public PlatformRecording newSnapshotClone(String reason, Boolean pathToGcRoots)
         if (state == RecordingState.DELAYED || state == RecordingState.NEW) {
             throw new IOException("Recording \"" + name + "\" (id=" + id + ") has not started, no content to write");
         }
+
         if (state == RecordingState.STOPPED) {
+            if (!isToDisk()) {
+                throw new IOException("Recording \"" + name + "\" (id=" + id + ")"
+                    + " is an in memory recording. No data to copy after it has been stopped.");
+            }
             PlatformRecording clone = recorder.newTemporaryRecording();
             for (RepositoryChunk r : chunks) {
                 clone.add(r);

src/jdk.jfr/share/classes/jdk/jfr/internal/WriteableUserPath.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2022, 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
@@ -136,7 +136,11 @@ public Void run() throws Exception {
         } catch (Throwable t) {
             // prevent malicious user to propagate exception callback
             // in the wrong context
-            throw new IOException("Unexpected error during I/O operation");
+            Throwable cause = null;
+            if (System.getSecurityManager() == null) {
+                cause = t;
+            }
+            throw new IOException("Unexpected error during I/O operation", cause);
         } finally {
             inPrivileged = false;
         }

test/jdk/jdk/jfr/api/recording/misc/TestRecordingCopy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2022, 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
@@ -29,6 +29,8 @@
 import jdk.test.lib.jfr.Events;
 import jdk.test.lib.jfr.SimpleEvent;
 
+import java.io.IOException;
+import java.nio.file.Paths;
 import java.util.List;
 
 /**
@@ -82,6 +84,27 @@ public static void main(String[] args) throws Exception {
         runningCopy.stop();
         runningCopy.close();
         stoppedCopy.close();
+
+        testMemoryCopy();
+    }
+
+    private static void testMemoryCopy() throws Exception {
+        try (Recording memory = new Recording()) {
+            memory.setToDisk(false);
+            memory.enable(SimpleEvent.class);
+            memory.start();
+
+            Recording unstopped = memory.copy(false);
+            unstopped.dump(Paths.get("unstopped-memory.jfr"));
+
+            Recording stopped = memory.copy(true);
+            try {
+                stopped.dump(Paths.get("stopped-memory.jfr"));
+                throw new Exception("Should not be able to dump stopped in memory recording");
+            } catch (IOException ioe) {
+                // As expected
+            }
+        }
     }
 
     /**