8313743: Make fields final in sun.nio.ch

Reviewed-by: bpb

src/java.base/share/classes/sun/nio/ch/AsynchronousChannelGroupImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2023, 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
@@ -59,7 +59,7 @@ abstract class AsynchronousChannelGroupImpl
     private final AtomicInteger threadCount = new AtomicInteger();
 
     // associated Executor for timeouts
-    private ScheduledThreadPoolExecutor timeoutExecutor;
+    private final ScheduledThreadPoolExecutor timeoutExecutor;
 
     // task queue for when using a fixed thread pool. In that case, a thread
     // waiting on I/O events must be awoken to poll tasks from this queue.

src/java.base/share/classes/sun/nio/ch/AsynchronousServerSocketChannelImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2023, 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
@@ -58,7 +58,7 @@ abstract class AsynchronousServerSocketChannelImpl
     private final Object stateLock = new Object();
 
     // close support
-    private ReadWriteLock closeLock = new ReentrantReadWriteLock();
+    private final ReadWriteLock closeLock = new ReentrantReadWriteLock();
     private volatile boolean closed;
 
     // set true when accept operation is cancelled

src/java.base/share/classes/sun/nio/ch/FileLockTable.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2023, 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
@@ -49,7 +49,7 @@ class FileLockTable {
      * FileLock (and FileChannel) alive.
      */
     private static class FileLockReference extends WeakReference<FileLock> {
-        private FileKey fileKey;
+        private final FileKey fileKey;
 
         FileLockReference(FileLock referent,
                           ReferenceQueue<FileLock> queue,
@@ -66,11 +66,11 @@ class FileLockTable {
     // The system-wide map is a ConcurrentHashMap that is keyed on the FileKey.
     // The map value is a list of file locks represented by FileLockReferences.
     // All access to the list must be synchronized on the list.
-    private static ConcurrentHashMap<FileKey, List<FileLockReference>> lockMap =
-        new ConcurrentHashMap<FileKey, List<FileLockReference>>();
+    private static final ConcurrentHashMap<FileKey, List<FileLockReference>> lockMap =
+        new ConcurrentHashMap<>();
 
     // reference queue for cleared refs
-    private static ReferenceQueue<FileLock> queue = new ReferenceQueue<FileLock>();
+    private static final ReferenceQueue<FileLock> queue = new ReferenceQueue<>();
 
     // The connection to which this table is connected
     private final Channel channel;

src/java.base/share/classes/sun/nio/ch/IOVecWrapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2023, 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
@@ -69,7 +69,7 @@ class IOVecWrapper {
     final long address;
 
     // Address size in bytes
-    static int addressSize;
+    static final int addressSize;
 
     private static class Deallocator implements Runnable {
         private final AllocatedNativeObject obj;

src/java.base/share/classes/sun/nio/ch/OptionKey.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2023, 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
@@ -30,8 +30,8 @@ package sun.nio.ch;
  */
 
 class OptionKey {
-    private int level;
-    private int name;
+    private final int level;
+    private final int name;
 
     OptionKey(int level, int name) {
         this.level = level;

src/java.base/share/classes/sun/nio/ch/Util.java

@@ -53,7 +53,7 @@ public class Util {
     private static final long MAX_CACHED_BUFFER_SIZE = getMaxCachedBufferSize();
 
     // Per-carrier-thread cache of temporary direct buffers
-    private static TerminatingThreadLocal<BufferCache> bufferCache = new TerminatingThreadLocal<>() {
+    private static final TerminatingThreadLocal<BufferCache> bufferCache = new TerminatingThreadLocal<>() {
         @Override
         protected BufferCache initialValue() {
             return new BufferCache();
@@ -112,7 +112,7 @@ public class Util {
      */
     private static class BufferCache {
         // the array of buffers
-        private ByteBuffer[] buffers;
+        private final ByteBuffer[] buffers;
 
         // the number of buffers in the cache
         private int count;
@@ -378,7 +378,7 @@ public class Util {
 
     // -- Unsafe access --
 
-    private static Unsafe unsafe = Unsafe.getUnsafe();
+    private static final Unsafe unsafe = Unsafe.getUnsafe();
 
     private static byte _get(long a) {
         return unsafe.getByte(a);