8189330: Cleanup FileDescriptor implementation

Reviewed-by: bpb

src/java.base/share/classes/java/io/FileCleanable.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2018, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 java.io;
+
+import jdk.internal.misc.JavaIOFileDescriptorAccess;
+import jdk.internal.misc.SharedSecrets;
+import jdk.internal.ref.CleanerFactory;
+import jdk.internal.ref.PhantomCleanable;
+
+import java.lang.ref.Cleaner;
+
+/**
+ * Cleanable for a FileDescriptor when it becomes phantom reachable.
+ * For regular fds on Unix and regular handles on Windows
+ * register a cleanup if fd != -1 or handle != -1.
+ * <p>
+ * Subclassed from {@code PhantomCleanable} so that {@code clear} can be
+ * called to disable the cleanup when the handle is closed by any means other
+ * than calling {@link FileDescriptor#close}.
+ * Otherwise, it might incorrectly close the handle after it has been reused.
+ */
+final class FileCleanable extends PhantomCleanable<FileDescriptor> {
+
+    // Access to FileDescriptor private fields;
+    // avoids making fd and handle package private
+    private static final JavaIOFileDescriptorAccess fdAccess =
+            SharedSecrets.getJavaIOFileDescriptorAccess();
+
+    /*
+     * Raw close of the file fd and/or handle.
+     * Used only for last chance cleanup.
+     */
+    private static native void cleanupClose0(int fd, long handle) throws IOException;
+
+    // The raw fd to close
+    private final int fd;
+
+    // The handle to close
+    private final long handle;
+
+    /**
+     * Register a Cleanable with the FileDescriptor
+     * if the FileDescriptor is non-null and valid.
+     * @implNote
+     * A exception (OutOfMemoryException) will leave the FileDescriptor
+     * having allocated resources and leak the fd/handle.
+     *
+     * @param fdo the FileDescriptor; may be null
+     */
+    static void register(FileDescriptor fdo) {
+        if (fdo != null && fdo.valid()) {
+            int fd = fdAccess.get(fdo);
+            long handle = fdAccess.getHandle(fdo);
+            fdo.registerCleanup(new FileCleanable(fdo, CleanerFactory.cleaner(), fd, handle));
+        }
+    }
+
+    /**
+     * Unregister a Cleanable from the FileDescriptor.
+     * @param fdo the FileDescriptor; may be null
+     */
+    static void unregister(FileDescriptor fdo) {
+        if (fdo != null) {
+            fdo.unregisterCleanup();
+        }
+    }
+
+    /**
+     * Constructor for a phantom cleanable reference.
+     *
+     * @param obj     the object to monitor
+     * @param cleaner the cleaner
+     * @param fd      file descriptor to close
+     * @param handle  handle to close
+     */
+    private FileCleanable(FileDescriptor obj, Cleaner cleaner, int fd, long handle) {
+        super(obj, cleaner);
+        this.fd = fd;
+        this.handle = handle;
+    }
+
+    /**
+     * Close the native handle or fd.
+     */
+    @Override
+    protected void performCleanup() {
+        try {
+            cleanupClose0(fd, handle);
+        } catch (IOException ioe) {
+            throw new UncheckedIOException("close", ioe);
+        }
+    }
+}