Add support for AutoCloseable objects to TempFileDeleter

h2/src/main/org/h2/util/TempFileDeleter.java

@@ -21,7 +21,7 @@ import org.h2.store.fs.FileUtils;
 public class TempFileDeleter {
 
     private final ReferenceQueue<Object> queue = new ReferenceQueue<>();
-    private final HashMap<PhantomReference<?>, String> refMap = new HashMap<>();
+    private final HashMap<PhantomReference<?>, Object> refMap = new HashMap<>();
 
     private TempFileDeleter() {
         // utility class
@@ -32,40 +32,47 @@ public class TempFileDeleter {
     }
 
     /**
-     * Add a file to the list of temp files to delete. The file is deleted once
-     * the file object is garbage collected.
+     * Add a file or a closeable to the list of temporary objects to delete. The
+     * file is deleted once the file object is garbage collected.
      *
-     * @param fileName the file name
-     * @param file the object to monitor
-     * @return the reference that can be used to stop deleting the file
+     * @param resource the file name or the closeable
+     * @param monitor the object to monitor
+     * @return the reference that can be used to stop deleting the file or closing the closeable
      */
-    public synchronized Reference<?> addFile(String fileName, Object file) {
-        IOUtils.trace("TempFileDeleter.addFile", fileName, file);
-        PhantomReference<?> ref = new PhantomReference<>(file, queue);
-        refMap.put(ref, fileName);
+    public synchronized Reference<?> addFile(Object resource, Object monitor) {
+        if (!(resource instanceof String) && !(resource instanceof AutoCloseable)) {
+            throw DbException.getUnsupportedException("Unsupported resource " + resource);
+        }
+        IOUtils.trace("TempFileDeleter.addFile",
+                resource instanceof String ? (String) resource : "-", monitor);
+        PhantomReference<?> ref = new PhantomReference<>(monitor, queue);
+        refMap.put(ref, resource);
         deleteUnused();
         return ref;
     }
 
     /**
-     * Delete the given file now. This will remove the reference from the list.
+     * Delete the given file or close the closeable now. This will remove the
+     * reference from the list.
      *
      * @param ref the reference as returned by addFile
-     * @param fileName the file name
+     * @param resource the file name or closeable
      */
-    public synchronized void deleteFile(Reference<?> ref, String fileName) {
+    public synchronized void deleteFile(Reference<?> ref, Object resource) {
         if (ref != null) {
-            String f2 = refMap.remove(ref);
+            Object f2 = refMap.remove(ref);
             if (f2 != null) {
                 if (SysProperties.CHECK) {
-                    if (fileName != null && !f2.equals(fileName)) {
-                        DbException.throwInternalError("f2:" + f2 + " f:" + fileName);
+                    if (resource != null && !f2.equals(resource)) {
+                        DbException.throwInternalError("f2:" + f2 + " f:" + resource);
                     }
                 }
-                fileName = f2;
+                resource = f2;
             }
         }
-        if (fileName != null && FileUtils.exists(fileName)) {
+        if (resource instanceof String) {
+            String fileName = (String) resource;
+            if (FileUtils.exists(fileName)) {
                 try {
                     IOUtils.trace("TempFileDeleter.deleteFile", fileName, null);
                     FileUtils.tryDelete(fileName);
@@ -73,20 +80,29 @@ public class TempFileDeleter {
                     // TODO log such errors?
                 }
             }
+        } else if (resource instanceof AutoCloseable) {
+            AutoCloseable closeable = (AutoCloseable) resource;
+            try {
+                IOUtils.trace("TempFileDeleter.deleteCloseable", "-", null);
+                closeable.close();
+            } catch (Exception e) {
+                // TODO log such errors?
+            }
+        }
     }
 
     /**
-     * Delete all registered temp files.
+     * Delete all registered temp resources.
      */
     public void deleteAll() {
-        for (String tempFile : new ArrayList<>(refMap.values())) {
-            deleteFile(null, tempFile);
+        for (Object resource : new ArrayList<>(refMap.values())) {
+            deleteFile(null, resource);
         }
         deleteUnused();
     }
 
     /**
-     * Delete all unused files now.
+     * Delete all unused resources now.
      */
     public void deleteUnused() {
         while (queue != null) {
@@ -99,20 +115,21 @@ public class TempFileDeleter {
     }
 
     /**
-     * This method is called if a file should no longer be deleted if the object
-     * is garbage collected.
+     * This method is called if a file should no longer be deleted or a resource
+     * should no longer be closed if the object is garbage collected.
      *
      * @param ref the reference as returned by addFile
-     * @param fileName the file name
+     * @param resource file name or closeable
      */
-    public void stopAutoDelete(Reference<?> ref, String fileName) {
-        IOUtils.trace("TempFileDeleter.stopAutoDelete", fileName, ref);
+    public void stopAutoDelete(Reference<?> ref, Object resource) {
+        IOUtils.trace("TempFileDeleter.stopAutoDelete",
+                resource instanceof String ? (String) resource : "-", ref);
         if (ref != null) {
-            String f2 = refMap.remove(ref);
+            Object f2 = refMap.remove(ref);
             if (SysProperties.CHECK) {
-                if (f2 == null || !f2.equals(fileName)) {
+                if (f2 == null || !f2.equals(resource)) {
                     DbException.throwInternalError("f2:" + f2 +
-                            " " + (f2 == null ? "" : f2) + " f:" + fileName);
+                            " " + (f2 == null ? "" : f2) + " f:" + resource);
                 }
             }
         }