8196535: Remove support for pre-Java 6 non-JVM-wide file locking

Reviewed-by: alanb, rriggs

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 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
@@ -136,7 +136,7 @@ abstract class AsynchronousFileChannelImpl
         if (fileLockTable == null) {
             synchronized (this) {
                 if (fileLockTable == null) {
-                    fileLockTable = FileLockTable.newSharedFileLockTable(this, fdObj);
+                    fileLockTable = new FileLockTable(this, fdObj);
                 }
             }
         }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -1083,49 +1083,19 @@ public class FileChannelImpl
 
     // -- Locks --
 
-
-
     // keeps track of locks on this file
     private volatile FileLockTable fileLockTable;
 
-    // indicates if file locks are maintained system-wide (as per spec)
-    private static boolean isSharedFileLockTable;
-
-    // indicates if the disableSystemWideOverlappingFileLockCheck property
-    // has been checked
-    private static volatile boolean propertyChecked;
-
-    // The lock list in J2SE 1.4/5.0 was local to each FileChannel instance so
-    // the overlap check wasn't system wide when there were multiple channels to
-    // the same file. This property is used to get 1.4/5.0 behavior if desired.
-    private static boolean isSharedFileLockTable() {
-        if (!propertyChecked) {
-            synchronized (FileChannelImpl.class) {
-                if (!propertyChecked) {
-                    String value = GetPropertyAction.privilegedGetProperty(
-                            "sun.nio.ch.disableSystemWideOverlappingFileLockCheck");
-                    isSharedFileLockTable = ((value == null) || value.equals("false"));
-                    propertyChecked = true;
-                }
-            }
-        }
-        return isSharedFileLockTable;
-    }
-
     private FileLockTable fileLockTable() throws IOException {
         if (fileLockTable == null) {
             synchronized (this) {
                 if (fileLockTable == null) {
-                    if (isSharedFileLockTable()) {
+                    int ti = threads.add();
-                        int ti = threads.add();
+                    try {
-                        try {
+                        ensureOpen();
-                            ensureOpen();
+                        fileLockTable = new FileLockTable(this, fd);
-                            fileLockTable = FileLockTable.newSharedFileLockTable(this, fd);
+                    } finally {
-                        } finally {
+                        threads.remove(ti);
-                            threads.remove(ti);
-                        }
-                    } else {
-                        fileLockTable = new SimpleFileLockTable();
                     }
                 }
             }
@@ -1229,59 +1199,6 @@ public class FileChannelImpl
         fileLockTable.remove(fli);
     }
 
-    // -- File lock support --
-
-    /**
-     * A simple file lock table that maintains a list of FileLocks obtained by a
-     * FileChannel. Use to get 1.4/5.0 behaviour.
-     */
-    private static class SimpleFileLockTable extends FileLockTable {
-        // synchronize on list for access
-        private final List<FileLock> lockList = new ArrayList<FileLock>(2);
-
-        public SimpleFileLockTable() {
-        }
-
-        private void checkList(long position, long size)
-            throws OverlappingFileLockException
-        {
-            assert Thread.holdsLock(lockList);
-            for (FileLock fl: lockList) {
-                if (fl.overlaps(position, size)) {
-                    throw new OverlappingFileLockException();
-                }
-            }
-        }
-
-        public void add(FileLock fl) throws OverlappingFileLockException {
-            synchronized (lockList) {
-                checkList(fl.position(), fl.size());
-                lockList.add(fl);
-            }
-        }
-
-        public void remove(FileLock fl) {
-            synchronized (lockList) {
-                lockList.remove(fl);
-            }
-        }
-
-        public List<FileLock> removeAll() {
-            synchronized(lockList) {
-                List<FileLock> result = new ArrayList<FileLock>(lockList);
-                lockList.clear();
-                return result;
-            }
-        }
-
-        public void replace(FileLock fl1, FileLock fl2) {
-            synchronized (lockList) {
-                lockList.remove(fl1);
-                lockList.add(fl2);
-            }
-        }
-    }
-
     // -- Native methods --
 
     // Creates a new mapping

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

@@ -25,64 +25,27 @@
 
 package sun.nio.ch;
 
-import java.nio.channels.*;
-import java.util.*;
-import java.util.concurrent.ConcurrentHashMap;
-import java.lang.ref.*;
 import java.io.FileDescriptor;
 import java.io.IOException;
-
+import java.lang.ref.ReferenceQueue;
-abstract class FileLockTable {
+import java.lang.ref.WeakReference;
-    protected FileLockTable() {
+import java.nio.channels.Channel;
-    }
+import java.nio.channels.FileLock;
-
+import java.nio.channels.OverlappingFileLockException;
-    /**
+import java.util.ArrayList;
-     * Creates and returns a file lock table for a channel that is connected to
+import java.util.HashSet;
-     * the a system-wide map of all file locks for the Java virtual machine.
+import java.util.List;
-     */
+import java.util.Set;
-    public static FileLockTable newSharedFileLockTable(Channel channel,
+import java.util.concurrent.ConcurrentHashMap;
-                                                       FileDescriptor fd)
-        throws IOException
-    {
-        return new SharedFileLockTable(channel, fd);
-    }
-
-    /**
-     * Adds a file lock to the table.
-     *
-     * @throws OverlappingFileLockException if the file lock overlaps
-     *         with an existing file lock in the table
-     */
-    public abstract void add(FileLock fl) throws OverlappingFileLockException;
-
-    /**
-     * Remove an existing file lock from the table.
-     */
-    public abstract void remove(FileLock fl);
-
-    /**
-     * Removes all file locks from the table.
-     *
-     * @return  The list of file locks removed
-     */
-    public abstract List<FileLock> removeAll();
-
-    /**
-     * Replaces an existing file lock in the table.
-     */
-    public abstract void replace(FileLock fl1, FileLock fl2);
-}
-
 
 /**
  * A file lock table that is over a system-wide map of all file locks.
  */
-class SharedFileLockTable extends FileLockTable {
+class FileLockTable {
-
     /**
      * A weak reference to a FileLock.
      * <p>
-     * SharedFileLockTable uses a list of file lock references to avoid keeping the
+     * FileLockTable uses a list of file lock references to avoid keeping the
      * FileLock (and FileChannel) alive.
      */
     private static class FileLockReference extends WeakReference<FileLock> {
@@ -118,14 +81,17 @@ class SharedFileLockTable extends FileLockTable {
     // Locks obtained for this channel
     private final Set<FileLock> locks;
 
-    SharedFileLockTable(Channel channel, FileDescriptor fd) throws IOException {
+    /**
+     * Creates a file lock table for a channel that is connected to the
+     * system-wide map of all file locks for the Java virtual machine.
+     */
+    FileLockTable(Channel channel, FileDescriptor fd) throws IOException {
         this.channel = channel;
         this.fileKey = FileKey.create(fd);
         this.locks = new HashSet<FileLock>();
     }
 
-    @Override
+    void add(FileLock fl) throws OverlappingFileLockException {
-    public void add(FileLock fl) throws OverlappingFileLockException {
         List<FileLockReference> list = lockMap.get(fileKey);
 
         for (;;) {
@@ -176,8 +142,7 @@ class SharedFileLockTable extends FileLockTable {
         }
     }
 
-    @Override
+    void remove(FileLock fl) {
-    public void remove(FileLock fl) {
         assert fl != null;
 
         // the lock must exist so the list of locks must be present
@@ -201,8 +166,7 @@ class SharedFileLockTable extends FileLockTable {
         }
     }
 
-    @Override
+    List<FileLock> removeAll() {
-    public List<FileLock> removeAll() {
         List<FileLock> result = new ArrayList<FileLock>();
         List<FileLockReference> list = lockMap.get(fileKey);
         if (list != null) {
@@ -234,8 +198,7 @@ class SharedFileLockTable extends FileLockTable {
         return result;
     }
 
-    @Override
+    void replace(FileLock fromLock, FileLock toLock) {
-    public void replace(FileLock fromLock, FileLock toLock) {
         // the lock must exist so there must be a list
         List<FileLockReference> list = lockMap.get(fileKey);
         assert list != null;