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src/java.base/share/classes/java/io/BufferedInputStream.java
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rev 13993 : 8153334: Replace BufferedInputStreams use of AtomicReferenceFieldUpdater with Unsafe
Reviewed-by: TBD
*** 22,32 ****
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.io;
- import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
/**
* A <code>BufferedInputStream</code> adds
* functionality to another input stream-namely,
* the ability to buffer the input and to
--- 22,31 ----
*** 66,84 ****
* a different size.
*/
protected volatile byte buf[];
/**
! * Atomic updater to provide compareAndSet for buf. This is
! * necessary because closes can be asynchronous. We use nullness
* of buf[] as primary indicator that this stream is closed. (The
* "in" field is also nulled out on close.)
*/
! private static final
! AtomicReferenceFieldUpdater<BufferedInputStream, byte[]> bufUpdater =
! AtomicReferenceFieldUpdater.newUpdater
! (BufferedInputStream.class, byte[].class, "buf");
/**
* The index one greater than the index of the last valid byte in
* the buffer.
* This value is always
--- 65,90 ----
* a different size.
*/
protected volatile byte buf[];
/**
! * Get Unsafe and offset of buf to provide compareAndSet functionality.
! * This is necessary because closes can be asynchronous. We use nullness
* of buf[] as primary indicator that this stream is closed. (The
* "in" field is also nulled out on close.)
*/
! private static final jdk.internal.misc.Unsafe U =
! jdk.internal.misc.Unsafe.getUnsafe();
! private static final long BUF_OFFSET;
! static {
! try {
! BUF_OFFSET = U.objectFieldOffset
! (BufferedInputStream.class.getDeclaredField("buf"));
! } catch (ReflectiveOperationException e) {
! throw new Error(e);
! }
! }
/**
* The index one greater than the index of the last valid byte in
* the buffer.
* This value is always
*** 230,240 ****
pos * 2 : MAX_BUFFER_SIZE;
if (nsz > marklimit)
nsz = marklimit;
byte nbuf[] = new byte[nsz];
System.arraycopy(buffer, 0, nbuf, 0, pos);
! if (!bufUpdater.compareAndSet(this, buffer, nbuf)) {
// Can't replace buf if there was an async close.
// Note: This would need to be changed if fill()
// is ever made accessible to multiple threads.
// But for now, the only way CAS can fail is via close.
// assert buf == null;
--- 236,246 ----
pos * 2 : MAX_BUFFER_SIZE;
if (nsz > marklimit)
nsz = marklimit;
byte nbuf[] = new byte[nsz];
System.arraycopy(buffer, 0, nbuf, 0, pos);
! if (!U.compareAndSwapObject(this, BUF_OFFSET, buffer, nbuf)) {
// Can't replace buf if there was an async close.
// Note: This would need to be changed if fill()
// is ever made accessible to multiple threads.
// But for now, the only way CAS can fail is via close.
// assert buf == null;
*** 474,484 ****
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
byte[] buffer;
while ( (buffer = buf) != null) {
! if (bufUpdater.compareAndSet(this, buffer, null)) {
InputStream input = in;
in = null;
if (input != null)
input.close();
return;
--- 480,490 ----
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
byte[] buffer;
while ( (buffer = buf) != null) {
! if (U.compareAndSwapObject(this, BUF_OFFSET, buffer, null)) {
InputStream input = in;
in = null;
if (input != null)
input.close();
return;
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