getCurrentThreadAllocatedBytes default implementation s/b getThreadAllocatedBytes

Original CSR: https://bugs.openjdk.java.net/browse/JDK-8232072

There is a pair of original CSRs that need to be backported together:

• CSR 1: https://bugs.openjdk.java.net/browse/JDK-8231374
• CSR 2: https://bugs.openjdk.java.net/browse/JDK-8232072

For CSR 1 the backport is https://bugs.openjdk.java.net/browse/JDK-8249101

For CSR 2 the backport is this CSR.

The only difference from the original CSR https://bugs.openjdk.java.net/browse/JDK-8232072 is that the version tag for method getCurrentThreadAllocatedBytes was changed from "@since 14" and "@since 11.0.9".

Summary

To match its abstract specification, change the default implementation of com.sun.management.ThreadMXBean.getCurrentThreadAllocatedBytes to return the value of getThreadAllocatedBytes(Thread.currentThread().getId()).

Problem

The existing default implementation of com.sun.management.ThreadMXBean.getCurrentThreadAllocatedBytes is to throw UnsupportedOperationException, which is permitted but doesn't match the abstract specification of the method.

Solution

Change the default implementation of com.sun.management.ThreadMXBean.getCurrentThreadAllocatedBytes to return the value of getThreadAllocatedBytes(Thread.currentThread().getId()).

Remove the @implSpec portion of the Javadoc that described the throwing of the exception.

Specification

/**
 * Returns an approximation of the total amount of memory, in bytes,
 * allocated in heap memory for the current thread.
 * The returned value is an approximation because some Java virtual machine
 * implementations may use object allocation mechanisms that result in a
 * delay between the time an object is allocated and the time its size is
 * recorded.
 *
 * <p>
 * This is a convenience method for local management use and is
 * equivalent to calling:
 * <blockquote><pre>
 *   {@link #getThreadAllocatedBytes getThreadAllocatedBytes}(Thread.currentThread().getId());
 * </pre></blockquote>
 *
-* @implSpec The default implementation throws
-* {@code UnsupportedOperationException}.
-*
 * @return an approximation of the total memory allocated, in bytes, in
 * heap memory for the current thread
 * if thread memory allocation measurement is enabled;
 * {@code -1} otherwise.
 *
 * @throws java.lang.UnsupportedOperationException if the Java virtual
 *         machine implementation does not support thread memory allocation
 *         measurement.
 *
 * @see #isThreadAllocatedMemorySupported
 * @see #isThreadAllocatedMemoryEnabled
 * @see #setThreadAllocatedMemoryEnabled
 */
public default long getCurrentThreadAllocatedBytes() {
    return getThreadAllocatedBytes(Thread.currentThread().getId());
}