--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/nio/MappedByteBuffer.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,169 @@
+/*
+ * Copyright 2000-2003 Sun Microsystems, Inc. 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. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.nio;
+
+
+/**
+ * A direct byte buffer whose content is a memory-mapped region of a file.
+ *
+ * <p> Mapped byte buffers are created via the {@link
+ * java.nio.channels.FileChannel#map FileChannel.map} method. This class
+ * extends the {@link ByteBuffer} class with operations that are specific to
+ * memory-mapped file regions.
+ *
+ * <p> A mapped byte buffer and the file mapping that it represents remain
+ * valid until the buffer itself is garbage-collected.
+ *
+ * <p> The content of a mapped byte buffer can change at any time, for example
+ * if the content of the corresponding region of the mapped file is changed by
+ * this program or another. Whether or not such changes occur, and when they
+ * occur, is operating-system dependent and therefore unspecified.
+ *
+ * <a name="inaccess"><p> All or part of a mapped byte buffer may become
+ * inaccessible at any time, for example if the mapped file is truncated. An
+ * attempt to access an inaccessible region of a mapped byte buffer will not
+ * change the buffer's content and will cause an unspecified exception to be
+ * thrown either at the time of the access or at some later time. It is
+ * therefore strongly recommended that appropriate precautions be taken to
+ * avoid the manipulation of a mapped file by this program, or by a
+ * concurrently running program, except to read or write the file's content.
+ *
+ * <p> Mapped byte buffers otherwise behave no differently than ordinary direct
+ * byte buffers. </p>
+ *
+ *
+ * @author Mark Reinhold
+ * @author JSR-51 Expert Group
+ * @since 1.4
+ */
+
+public abstract class MappedByteBuffer
+ extends ByteBuffer
+{
+
+ // This is a little bit backwards: By rights MappedByteBuffer should be a
+ // subclass of DirectByteBuffer, but to keep the spec clear and simple, and
+ // for optimization purposes, it's easier to do it the other way around.
+ // This works because DirectByteBuffer is a package-private class.
+
+ // Volatile to make sure that the finalization thread sees the current
+ // value of this so that a region is not accidentally unmapped again later.
+ volatile boolean isAMappedBuffer; // package-private
+
+ // This should only be invoked by the DirectByteBuffer constructors
+ //
+ MappedByteBuffer(int mark, int pos, int lim, int cap, // package-private
+ boolean mapped)
+ {
+ super(mark, pos, lim, cap);
+ isAMappedBuffer = mapped;
+ }
+
+ MappedByteBuffer(int mark, int pos, int lim, int cap) { // package-private
+ super(mark, pos, lim, cap);
+ isAMappedBuffer = false;
+ }
+
+ private void checkMapped() {
+ if (!isAMappedBuffer)
+ // Can only happen if a luser explicitly casts a direct byte buffer
+ throw new UnsupportedOperationException();
+ }
+
+ /**
+ * Tells whether or not this buffer's content is resident in physical
+ * memory.
+ *
+ * <p> A return value of <tt>true</tt> implies that it is highly likely
+ * that all of the data in this buffer is resident in physical memory and
+ * may therefore be accessed without incurring any virtual-memory page
+ * faults or I/O operations. A return value of <tt>false</tt> does not
+ * necessarily imply that the buffer's content is not resident in physical
+ * memory.
+ *
+ * <p> The returned value is a hint, rather than a guarantee, because the
+ * underlying operating system may have paged out some of the buffer's data
+ * by the time that an invocation of this method returns. </p>
+ *
+ * @return <tt>true</tt> if it is likely that this buffer's content
+ * is resident in physical memory
+ */
+ public final boolean isLoaded() {
+ checkMapped();
+ if ((address == 0) || (capacity() == 0))
+ return true;
+ return isLoaded0(((DirectByteBuffer)this).address(), capacity());
+ }
+
+ /**
+ * Loads this buffer's content into physical memory.
+ *
+ * <p> This method makes a best effort to ensure that, when it returns,
+ * this buffer's content is resident in physical memory. Invoking this
+ * method may cause some number of page faults and I/O operations to
+ * occur. </p>
+ *
+ * @return This buffer
+ */
+ public final MappedByteBuffer load() {
+ checkMapped();
+ if ((address == 0) || (capacity() == 0))
+ return this;
+ load0(((DirectByteBuffer)this).address(), capacity(), Bits.pageSize());
+ return this;
+ }
+
+ /**
+ * Forces any changes made to this buffer's content to be written to the
+ * storage device containing the mapped file.
+ *
+ * <p> If the file mapped into this buffer resides on a local storage
+ * device then when this method returns it is guaranteed that all changes
+ * made to the buffer since it was created, or since this method was last
+ * invoked, will have been written to that device.
+ *
+ * <p> If the file does not reside on a local device then no such guarantee
+ * is made.
+ *
+ * <p> If this buffer was not mapped in read/write mode ({@link
+ * java.nio.channels.FileChannel.MapMode#READ_WRITE}) then invoking this
+ * method has no effect. </p>
+ *
+ * @return This buffer
+ */
+ public final MappedByteBuffer force() {
+ checkMapped();
+ if ((address == 0) || (capacity() == 0))
+ return this;
+ force0(((DirectByteBuffer)this).address(), capacity());
+ return this;
+ }
+
+ private native boolean isLoaded0(long address, long length);
+ private native int load0(long address, long length, int pageSize);
+ private native void force0(long address, long length);
+
+}