Fix WindowsFS onClose race condition (#15951)

* Fix WindowsFS onClose race condition

* add changelog and fix styling

---------

Co-authored-by: Uwe Schindler <uschindler@apache.org>
Co-authored-by: Dawid Weiss <dawid.weiss@carrotsearch.com>

Author: 3 people

lucene/CHANGES.txt

@@ -378,6 +378,8 @@ Other
 
 * GITHUB#15891: Add the ability to pass DataAccessHints in Lucene104ScalarQuantizedVectorsReader (Navneet Verma)
 
+* GITHUB#15951: Fix WindowsFS onClose race condition (Szymon Bialkowski)
+
 ======================= Lucene 10.4.0 =======================
 
 API Changes

lucene/test-framework/src/java/org/apache/lucene/tests/mockfile/WindowsFS.java

@@ -74,10 +74,12 @@ protected void onOpen(Path path, Object stream) throws IOException {
 
   @Override
   protected void onClose(Path path, Object stream) throws IOException {
-    Object key = getKey(path); // here we can read this outside of the lock
     synchronized (openFiles) {
+      // we have to read the key under the lock; otherwise concurrent move might change the inode
+      // of the path and therefore the key, meaning won't be able to find it in openFiles
+      Object key = getKey(path);
       Map<Path, Integer> pathMap = openFiles.get(key);
-      assert pathMap != null;
+      assert pathMap != null : "no open file for key " + key + " on path " + path;
       assert pathMap.containsKey(path);
       Integer v = pathMap.get(path);
       if (v != null) {