726 lines
26 KiB
Java
726 lines
26 KiB
Java
/*
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* Written by Cliff Click and released to the public domain, as explained at
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* http://creativecommons.org/licenses/publicdomain
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*/
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package it.tdlight.util;
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import java.io.IOException;
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import java.io.Serializable;
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import java.lang.reflect.Field;
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import java.util.AbstractSet;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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import java.util.concurrent.atomic.AtomicInteger;
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import org.jctools.maps.ConcurrentAutoTable;
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import org.jctools.util.UnsafeAccess;
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import sun.misc.Unsafe;
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/**
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* A multi-threaded bit-vector set, implemented as an array of primitive
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* {@code longs}. All operations are non-blocking and multi-threaded safe.
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* {@link #contains(int)} calls are roughly the same speed as a {load, mask}
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* sequence. {@link #add(int)} and {@link #remove(int)} calls are a tad more
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* expensive than a {load, mask, store} sequence because they must use a CAS.
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* The bit-vector is auto-sizing.
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*
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* <p><em>General note of caution:</em> The Set API allows the use of {@link Integer}
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* with silent autoboxing - which can be very expensive if many calls are
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* being made. Since autoboxing is silent you may not be aware that this is
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* going on. The built-in API takes lower-case {@code ints} and is much more
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* efficient.
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*
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* <p>Space: space is used in proportion to the largest element, as opposed to
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* the number of elements (as is the case with hash-table based Set
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* implementations). Space is approximately (largest_element/8 + 64) bytes.
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*
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* The implementation is a simple bit-vector using CAS for update.
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*
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* @since 1.5
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* @author Cliff Click
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*/
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public class NonBlockingSetInt extends AbstractSet<Integer> implements Serializable {
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private static final long serialVersionUID = 1234123412341234123L;
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private static final Unsafe _unsafe = UnsafeAccess.UNSAFE;
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// --- Bits to allow atomic update of the NBSI
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private static final long _nbsi_offset;
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static { // <clinit>
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Field f = null;
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try {
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f = NonBlockingSetInt.class.getDeclaredField("_nbsi");
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} catch( NoSuchFieldException e ) {
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}
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_nbsi_offset = _unsafe.objectFieldOffset(f);
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}
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private final boolean CAS_nbsi( NBSI old, NBSI nnn ) {
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return _unsafe.compareAndSwapObject(this, _nbsi_offset, old, nnn );
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}
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// The actual Set of Joy, which changes during a resize event. The
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// Only Field for this class, so I can atomically change the entire
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// set implementation with a single CAS.
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private transient NBSI _nbsi;
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/** Create a new empty bit-vector */
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public NonBlockingSetInt( ) {
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_nbsi = new NBSI(63, new ConcurrentAutoTable(), this); // The initial 1-word set
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}
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private NonBlockingSetInt(NonBlockingSetInt a, NonBlockingSetInt b) {
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_nbsi = new NBSI(a._nbsi,b._nbsi,new ConcurrentAutoTable(),this);
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}
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/**
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* Overridden to avoid auto-boxing for NonBlockingSetInt.
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*
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* @param c The collection to add to this set.
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* @return True if the set was modified.
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*/
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@Override
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public boolean addAll(Collection<? extends Integer> c) {
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if (!NonBlockingSetInt.class.equals(c.getClass())) {
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return super.addAll(c);
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}
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boolean modified = false;
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for (final IntIterator it = ((NonBlockingSetInt)c).intIterator(); it.hasNext(); ) {
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modified |= add(it.next());
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}
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return modified;
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}
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/**
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* Overridden to avoid auto-boxing for NonBlockingSetInt.
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*
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* @param c The collection to remove from this set.
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* @return True if the set was modified.
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*/
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@Override
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public boolean removeAll(Collection<?> c) {
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if (!NonBlockingSetInt.class.equals(c.getClass())) {
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return super.removeAll(c);
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}
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boolean modified = false;
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for (final IntIterator it = ((NonBlockingSetInt)c).intIterator(); it.hasNext(); ) {
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modified |= remove(it.next());
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}
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return modified;
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}
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@Override
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public boolean containsAll(Collection<?> c) {
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if (!NonBlockingSetInt.class.equals(c.getClass())) {
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return super.containsAll(c);
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}
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for (final IntIterator it = ((NonBlockingSetInt)c).intIterator(); it.hasNext(); ) {
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if (!contains(it.next())) {
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return false;
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}
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}
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return true;
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}
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@Override
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public boolean retainAll(Collection<?> c) {
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if (!NonBlockingSetInt.class.equals(c.getClass())) {
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return super.retainAll(c);
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}
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boolean modified = false;
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final NonBlockingSetInt nonBlockingSetInt = (NonBlockingSetInt) c;
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for (final IntIterator it = intIterator(); it.hasNext(); ) {
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if (!nonBlockingSetInt.contains(it.next())) {
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it.remove();
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modified = true;
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}
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}
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return modified;
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}
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@Override
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public int hashCode() {
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int hashCode = 0;
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for (final IntIterator it = intIterator(); it.hasNext(); ) {
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hashCode += it.next();
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}
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return hashCode;
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}
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/**
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* Add {@code i} to the set. Uppercase {@link Integer} version of add,
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* requires auto-unboxing. When possible use the {@code int} version of
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* {@link #add(int)} for efficiency.
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* @throws IllegalArgumentException if i is negative.
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* @return <tt>true</tt> if i was added to the set.
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*/
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@Override
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public boolean add ( final Integer i ) {
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return add(i.intValue());
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}
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/**
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* Test if {@code o} is in the set. This is the uppercase {@link Integer}
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* version of contains, requires a type-check and auto-unboxing. When
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* possible use the {@code int} version of {@link #contains(int)} for
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* efficiency.
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* @return <tt>true</tt> if i was in the set.
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*/
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@Override
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public boolean contains( final Object o ) {
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return o instanceof Integer && contains(((Integer) o).intValue());
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}
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/**
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* Remove {@code o} from the set. This is the uppercase {@link Integer}
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* version of remove, requires a type-check and auto-unboxing. When
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* possible use the {@code int} version of {@link #remove(int)} for
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* efficiency.
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* @return <tt>true</tt> if i was removed to the set.
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*/
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@Override
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public boolean remove( final Object o ) {
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return o instanceof Integer && remove(((Integer) o).intValue());
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}
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/**
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* Add {@code i} to the set. This is the lower-case '{@code int}' version
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* of {@link #add} - no autoboxing. Negative values throw
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* IllegalArgumentException.
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* @throws IllegalArgumentException if i is negative.
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* @return <tt>true</tt> if i was added to the set.
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*/
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public boolean add( final int i ) {
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if( i < 0 ) throw new IllegalArgumentException(""+i);
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return _nbsi.add(i);
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}
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/**
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* Test if {@code i} is in the set. This is the lower-case '{@code int}'
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* version of {@link #contains} - no autoboxing.
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* @return <tt>true</tt> if i was int the set.
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*/
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public boolean contains( final int i ) { return i >= 0 && _nbsi.contains(i); }
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/**
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* Remove {@code i} from the set. This is the fast lower-case '{@code int}'
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* version of {@link #remove} - no autoboxing.
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* @return <tt>true</tt> if i was added to the set.
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*/
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public boolean remove ( final int i ) { return i >= 0 && _nbsi.remove(i); }
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/**
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* Current count of elements in the set. Due to concurrent racing updates,
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* the size is only ever approximate. Updates due to the calling thread are
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* immediately visible to calling thread.
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* @return count of elements.
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*/
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@Override
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public int size ( ) { return _nbsi.size( ); }
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/** Empty the bitvector. */
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@Override
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public void clear ( ) {
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NBSI cleared = new NBSI(63, new ConcurrentAutoTable(), this); // An empty initial NBSI
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while( !CAS_nbsi( _nbsi, cleared ) ) // Spin until clear works
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;
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}
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@Override
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public String toString() {
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// Overloaded to avoid auto-boxing
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final IntIterator it = intIterator();
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if (!it.hasNext()) {
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return "[]";
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}
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final StringBuilder sb = new StringBuilder().append('[');
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for (;;) {
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sb.append(it.next());
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if (!it.hasNext()) {
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return sb.append(']').toString();
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}
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sb.append(", ");
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}
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}
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public int sizeInBytes() { return _nbsi.sizeInBytes(); }
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/*****************************************************************
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*
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* bitwise comparisons optimised for NBSI
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*
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*****************************************************************/
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public NonBlockingSetInt intersect(final NonBlockingSetInt op) {
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NonBlockingSetInt res = new NonBlockingSetInt(this,op);
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res._nbsi.intersect(res._nbsi, this._nbsi, op._nbsi);
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return res;
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}
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public NonBlockingSetInt union(final NonBlockingSetInt op) {
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NonBlockingSetInt res = new NonBlockingSetInt(this,op);
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res._nbsi.union(res._nbsi, this._nbsi, op._nbsi);
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return res;
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}
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// public NonBlockingSetInt not(final NonBlockingSetInt op) {
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//
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// }
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/** Verbose printout of internal structure for debugging. */
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public void print() { _nbsi.print(0); }
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/**
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* Standard Java {@link Iterator}. Not very efficient because it
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* auto-boxes the returned values.
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*/
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@Override
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public Iterator<Integer> iterator( ) { return new iter(); }
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public IntIterator intIterator() { return new NBSIIntIterator(); }
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private class NBSIIntIterator implements IntIterator {
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NBSI nbsi;
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int index = -1;
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int prev = -1;
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NBSIIntIterator() {
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nbsi = _nbsi;
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advance();
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}
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private void advance() {
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while( true ) {
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index++; // Next index
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while( (index>>6) >= nbsi._bits.length ) { // Index out of range?
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if( nbsi._new == null ) { // New table?
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index = -2; // No, so must be all done
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return; //
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}
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nbsi = nbsi._new; // Carry on, in the new table
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}
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if( nbsi.contains(index) ) return;
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}
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}
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@Override
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public int next() {
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if( index == -1 ) throw new NoSuchElementException();
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prev = index;
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advance();
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return prev;
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}
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@Override
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public boolean hasNext() {
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return index != -2;
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}
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@Override
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public void remove() {
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if( prev == -1 ) throw new IllegalStateException();
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nbsi.remove(prev);
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prev = -1;
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}
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}
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private class iter implements Iterator<Integer> {
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NBSIIntIterator intIterator;
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iter() { intIterator = new NBSIIntIterator(); }
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@Override
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public boolean hasNext() { return intIterator.hasNext(); }
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@Override
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public Integer next() { return intIterator.next(); }
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@Override
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public void remove() { intIterator.remove(); }
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}
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// --- writeObject -------------------------------------------------------
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// Write a NBSI to a stream
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private void writeObject(java.io.ObjectOutputStream s) throws IOException {
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s.defaultWriteObject(); // Nothing to write
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final NBSI nbsi = _nbsi; // The One Field is transient
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final int len = _nbsi._bits.length<<6;
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s.writeInt(len); // Write max element
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for( int i=0; i<len; i++ )
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s.writeBoolean( _nbsi.contains(i) );
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}
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// --- readObject --------------------------------------------------------
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// Read a CHM from a stream
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private void readObject(java.io.ObjectInputStream s) throws IOException, ClassNotFoundException {
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s.defaultReadObject(); // Read nothing
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final int len = s.readInt(); // Read max element
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_nbsi = new NBSI(len, new ConcurrentAutoTable(), this);
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for( int i=0; i<len; i++ ) // Read all bits
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if( s.readBoolean() )
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_nbsi.add(i);
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}
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// --- NBSI ----------------------------------------------------------------
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private static final class NBSI {
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// Back pointer to the parent wrapper; sorta like make the class non-static
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private transient final NonBlockingSetInt _non_blocking_set_int;
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// Used to count elements: a high-performance counter.
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private transient final ConcurrentAutoTable _size;
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// The Bits
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private final long _bits[];
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// --- Bits to allow Unsafe access to arrays
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private static final int _Lbase = _unsafe.arrayBaseOffset(long[].class);
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private static final int _Lscale = _unsafe.arrayIndexScale(long[].class);
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private static long rawIndex(final long[] ary, final int idx) {
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assert idx >= 0 && idx < ary.length;
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return _Lbase + idx * _Lscale;
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}
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private final boolean CAS( int idx, long old, long nnn ) {
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return _unsafe.compareAndSwapLong( _bits, rawIndex(_bits, idx), old, nnn );
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}
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// --- Resize
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// The New Table, only set once to non-zero during a resize.
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// Must be atomically set.
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private NBSI _new;
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private static final long _new_offset;
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static { // <clinit>
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Field f = null;
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try {
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f = NBSI.class.getDeclaredField("_new");
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} catch( NoSuchFieldException e ) {
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}
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_new_offset = _unsafe.objectFieldOffset(f);
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}
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private final boolean CAS_new( NBSI nnn ) {
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return _unsafe.compareAndSwapObject(this, _new_offset, null, nnn );
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}
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private transient final AtomicInteger _copyIdx; // Used to count bits started copying
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private transient final AtomicInteger _copyDone; // Used to count words copied in a resize operation
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private transient final int _sum_bits_length; // Sum of all nested _bits.lengths
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private static final long mask( int i ) { return 1L<<(i&63); }
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// I need 1 free bit out of 64 to allow for resize. I do this by stealing
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// the high order bit - but then I need to do something with adding element
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// number 63 (and friends). I could use a mod63 function but it's more
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// efficient to handle the mod-64 case as an exception.
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//
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// Every 64th bit is put in it's own recursive bitvector. If the low 6 bits
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// are all set, we shift them off and recursively operate on the _nbsi64 set.
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private final NBSI _nbsi64;
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private NBSI(int max_elem, ConcurrentAutoTable ctr, NonBlockingSetInt nonb ) {
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super();
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_non_blocking_set_int = nonb;
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_size = ctr;
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_copyIdx = ctr == null ? null : new AtomicInteger();
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_copyDone = ctr == null ? null : new AtomicInteger();
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// The main array of bits
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_bits = new long[(int)(((long)max_elem+63)>>>6)];
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// Every 64th bit is moved off to it's own subarray, so that the
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// sign-bit is free for other purposes
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_nbsi64 = ((max_elem+1)>>>6) == 0 ? null : new NBSI((max_elem+1)>>>6, null, null);
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_sum_bits_length = _bits.length + (_nbsi64==null ? 0 : _nbsi64._sum_bits_length);
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}
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/** built a new NBSI with buffers large enough to hold bitwise operations on the operands **/
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private NBSI(NBSI a, NBSI b, ConcurrentAutoTable ctr, NonBlockingSetInt nonb) {
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super();
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_non_blocking_set_int = nonb;
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_size = ctr;
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_copyIdx = ctr == null ? null : new AtomicInteger();
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_copyDone = ctr == null ? null : new AtomicInteger();
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if(!has_bits(a) && !has_bits(b)) {
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_bits = null;
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_nbsi64 = null;
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_sum_bits_length = 0;
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return;
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}
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// todo - clean this nastiness up
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// essentially just safely creates new empty buffers for each of the recursive bitsets
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if(!has_bits(a)) {
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_bits = new long[b._bits.length];
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_nbsi64 = new NBSI(null,b._nbsi64,null,null);
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} else if(!has_bits(b)) {
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_bits = new long[a._bits.length];
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_nbsi64 = new NBSI(null,a._nbsi64,null,null);
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} else {
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int bit_length = a._bits.length > b._bits.length ? a._bits.length : b._bits.length;
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_bits = new long[bit_length];
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_nbsi64 = new NBSI(a._nbsi64,b._nbsi64,null,null);
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}
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_sum_bits_length = _bits.length + _nbsi64._sum_bits_length;
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}
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private static boolean has_bits(NBSI n) {
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return n != null && n._bits != null;
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}
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// Lower-case 'int' versions - no autoboxing, very fast.
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// 'i' is known positive.
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public boolean add( final int i ) {
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// Check for out-of-range for the current size bit vector.
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// If so we need to grow the bit vector.
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if( (i>>6) >= _bits.length )
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return install_larger_new_bits(i). // Install larger pile-o-bits (duh)
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help_copy().add(i); // Finally, add to the new table
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// Handle every 64th bit via using a nested array
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NBSI nbsi = this; // The bit array being added into
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int j = i; // The bit index being added
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while( (j&63) == 63 ) { // Bit 64? (low 6 bits are all set)
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nbsi = nbsi._nbsi64; // Recurse
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j = j>>6; // Strip off low 6 bits (all set)
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}
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final long mask = mask(j);
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long old;
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do {
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old = nbsi._bits[j>>6]; // Read old bits
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if( old < 0 ) // Not mutable?
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// Not mutable: finish copy of word, and retry on copied word
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return help_copy_impl(i).help_copy().add(i);
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if( (old & mask) != 0 ) return false; // Bit is already set?
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} while( !nbsi.CAS( j>>6, old, old | mask ) );
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_size.add(1);
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return true;
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}
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public boolean remove( final int i ) {
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if( (i>>6) >= _bits.length ) // Out of bounds? Not in this array!
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return _new==null ? false : help_copy().remove(i);
|
|
|
|
// Handle every 64th bit via using a nested array
|
|
NBSI nbsi = this; // The bit array being added into
|
|
int j = i; // The bit index being added
|
|
while( (j&63) == 63 ) { // Bit 64? (low 6 bits are all set)
|
|
nbsi = nbsi._nbsi64; // Recurse
|
|
j = j>>6; // Strip off low 6 bits (all set)
|
|
}
|
|
|
|
final long mask = mask(j);
|
|
long old;
|
|
do {
|
|
old = nbsi._bits[j>>6]; // Read old bits
|
|
if( old < 0 ) // Not mutable?
|
|
// Not mutable: finish copy of word, and retry on copied word
|
|
return help_copy_impl(i).help_copy().remove(i);
|
|
if( (old & mask) == 0 ) return false; // Bit is already clear?
|
|
} while( !nbsi.CAS( j>>6, old, old & ~mask ) );
|
|
_size.add(-1);
|
|
return true;
|
|
}
|
|
|
|
public boolean contains( final int i ) {
|
|
if( (i>>6) >= _bits.length ) // Out of bounds? Not in this array!
|
|
return _new==null ? false : help_copy().contains(i);
|
|
|
|
// Handle every 64th bit via using a nested array
|
|
NBSI nbsi = this; // The bit array being added into
|
|
int j = i; // The bit index being added
|
|
while( (j&63) == 63 ) { // Bit 64? (low 6 bits are all set)
|
|
nbsi = nbsi._nbsi64; // Recurse
|
|
j = j>>6; // Strip off low 6 bits (all set)
|
|
}
|
|
|
|
final long mask = mask(j);
|
|
long old = nbsi._bits[j>>6]; // Read old bits
|
|
if( old < 0 ) // Not mutable?
|
|
// Not mutable: finish copy of word, and retry on copied word
|
|
return help_copy_impl(i).help_copy().contains(i);
|
|
// Yes mutable: test & return bit
|
|
return (old & mask) != 0;
|
|
}
|
|
|
|
/**
|
|
* Bitwise operations which store the result in this instance.
|
|
* Assumes that this instance contains ample buffer space to store the largest
|
|
* buffer from each NBSI in the recursive bitmap.
|
|
*
|
|
* Also assumes that this method is called during the construction process of
|
|
* the bitset before the instance could be leaked to multiple threads.
|
|
***/
|
|
public boolean intersect(NBSI dest, NBSI a, NBSI b) {
|
|
// terminate recursion if one bitset is missing data
|
|
// since that word should be left as 0L anyway
|
|
if(!has_bits(a) || !has_bits(b))
|
|
return true;
|
|
for(int i = 0; i < dest._bits.length; i++) {
|
|
long left = a.safe_read_word(i,0L);
|
|
long right = b.safe_read_word(i,0L);
|
|
dest._bits[i] = (left & right) & Long.MAX_VALUE; // mask sign bit
|
|
}
|
|
// todo - recompute size
|
|
return intersect(dest._nbsi64, a._nbsi64, b._nbsi64);
|
|
}
|
|
|
|
public boolean union(NBSI dest, NBSI a, NBSI b) {
|
|
// terminate recursion if neiter bitset has data
|
|
if(!has_bits(a) && !has_bits(b))
|
|
return true;
|
|
if(has_bits(a) || has_bits(b)) {
|
|
for(int i = 0; i < dest._bits.length; i++) {
|
|
long left = a == null ? 0L : a.safe_read_word(i,0);
|
|
long right = b == null ? 0L : b.safe_read_word(i,0);
|
|
dest._bits[i] = (left | right) & Long.MAX_VALUE;
|
|
}
|
|
}
|
|
return union(dest._nbsi64, a == null ? null : a._nbsi64, b == null ? null : b._nbsi64);
|
|
}
|
|
|
|
/**************************************************************************/
|
|
|
|
private long safe_read_word(int i, long default_word) {
|
|
if(i >= _bits.length) {
|
|
// allow reading past the end of the buffer filling in a default word
|
|
return default_word;
|
|
}
|
|
long word = _bits[i];
|
|
if(word < 0) {
|
|
NBSI nb = help_copy_impl(i);
|
|
if(nb._non_blocking_set_int == null) {
|
|
return default_word;
|
|
}
|
|
word = nb.help_copy()._bits[i];
|
|
}
|
|
return word;
|
|
}
|
|
|
|
public int sizeInBytes() { return (int)_bits.length; }
|
|
|
|
public int size() { return (int)_size.get(); }
|
|
|
|
// Must grow the current array to hold an element of size i
|
|
private NBSI install_larger_new_bits( final int i ) {
|
|
if( _new == null ) {
|
|
// Grow by powers of 2, to avoid minor grow-by-1's.
|
|
// Note: must grow by exact powers-of-2 or the by-64-bit trick doesn't work right
|
|
int sz = (_bits.length<<6)<<1;
|
|
// CAS to install a new larger size. Did it work? Did it fail? We
|
|
// don't know and don't care. Only One can be installed, so if
|
|
// another thread installed a too-small size, we can't help it - we
|
|
// must simply install our new larger size as a nested-resize table.
|
|
CAS_new(new NBSI(sz, _size, _non_blocking_set_int));
|
|
}
|
|
// Return self for 'fluid' programming style
|
|
return this;
|
|
}
|
|
|
|
// Help any top-level NBSI to copy until completed.
|
|
// Always return the _new version of *this* NBSI, in case we're nested.
|
|
private NBSI help_copy() {
|
|
// Pick some words to help with - but only help copy the top-level NBSI.
|
|
// Nested NBSI waits until the top is done before we start helping.
|
|
NBSI top_nbsi = _non_blocking_set_int._nbsi;
|
|
final int HELP = 8; // Tuning number: how much copy pain are we willing to inflict?
|
|
// We "help" by forcing individual bit indices to copy. However, bits
|
|
// come in lumps of 64 per word, so we just advance the bit counter by 64's.
|
|
int idx = top_nbsi._copyIdx.getAndAdd(64*HELP);
|
|
for( int i=0; i<HELP; i++ ) {
|
|
int j = idx+i*64;
|
|
j %= (top_nbsi._bits.length<<6); // Limit, wrap to array size; means we retry indices
|
|
top_nbsi.help_copy_impl(j );
|
|
top_nbsi.help_copy_impl(j+63); // Also force the nested-by-64 bit
|
|
}
|
|
|
|
// Top level guy ready to promote?
|
|
// Note: WE may not be the top-level guy!
|
|
if( top_nbsi._copyDone.get() == top_nbsi._sum_bits_length )
|
|
// One shot CAS to promote - it may fail since we are racing; others
|
|
// may promote as well
|
|
if( _non_blocking_set_int.CAS_nbsi( top_nbsi, top_nbsi._new ) ) {
|
|
//System.out.println("Promote at top level to size "+(_non_blocking_set_int._nbsi._bits.length<<6));
|
|
}
|
|
|
|
// Return the new bitvector for 'fluid' programming style
|
|
return _new;
|
|
}
|
|
|
|
// Help copy this one word. State Machine.
|
|
// (1) If not "made immutable" in the old array, set the sign bit to make
|
|
// it immutable.
|
|
// (2) If non-zero in old array & zero in new, CAS new from 0 to copy-of-old
|
|
// (3) If non-zero in old array & non-zero in new, CAS old to zero
|
|
// (4) Zero in old, new is valid
|
|
// At this point, old should be immutable-zero & new has a copy of bits
|
|
private NBSI help_copy_impl( int i ) {
|
|
// Handle every 64th bit via using a nested array
|
|
NBSI old = this; // The bit array being copied from
|
|
NBSI nnn = _new; // The bit array being copied to
|
|
if( nnn == null ) return this; // Promoted already
|
|
int j = i; // The bit index being added
|
|
while( (j&63) == 63 ) { // Bit 64? (low 6 bits are all set)
|
|
old = old._nbsi64; // Recurse
|
|
nnn = nnn._nbsi64; // Recurse
|
|
j = j>>6; // Strip off low 6 bits (all set)
|
|
}
|
|
|
|
// Transit from state 1: word is not immutable yet
|
|
// Immutable is in bit 63, the sign bit.
|
|
long bits = old._bits[j>>6];
|
|
while( bits >= 0 ) { // Still in state (1)?
|
|
long oldbits = bits;
|
|
bits |= mask(63); // Target state of bits: sign-bit means immutable
|
|
if( old.CAS( j>>6, oldbits, bits ) ) {
|
|
if( oldbits == 0 ) _copyDone.addAndGet(1);
|
|
break; // Success - old array word is now immutable
|
|
}
|
|
bits = old._bits[j>>6]; // Retry if CAS failed
|
|
}
|
|
|
|
// Transit from state 2: non-zero in old and zero in new
|
|
if( bits != mask(63) ) { // Non-zero in old?
|
|
long new_bits = nnn._bits[j>>6];
|
|
if( new_bits == 0 ) { // New array is still zero
|
|
new_bits = bits & ~mask(63); // Desired new value: a mutable copy of bits
|
|
// One-shot CAS attempt, no loop, from 0 to non-zero.
|
|
// If it fails, somebody else did the copy for us
|
|
if( !nnn.CAS( j>>6, 0, new_bits ) )
|
|
new_bits = nnn._bits[j>>6]; // Since it failed, get the new value
|
|
assert new_bits != 0;
|
|
}
|
|
|
|
// Transit from state 3: non-zero in old and non-zero in new
|
|
// One-shot CAS attempt, no loop, from non-zero to 0 (but immutable)
|
|
if( old.CAS( j>>6, bits, mask(63) ) )
|
|
_copyDone.addAndGet(1); // One more word finished copying
|
|
}
|
|
|
|
// Now in state 4: zero (and immutable) in old
|
|
|
|
// Return the self bitvector for 'fluid' programming style
|
|
return this;
|
|
}
|
|
|
|
private void print( int d, String msg ) {
|
|
for( int i=0; i<d; i++ )
|
|
System.out.print(" ");
|
|
System.out.println(msg);
|
|
}
|
|
|
|
private void print(int d) {
|
|
StringBuilder buf = new StringBuilder();
|
|
buf.append("NBSI - _bits.len=");
|
|
NBSI x = this;
|
|
while( x != null ) {
|
|
buf.append(" "+x._bits.length);
|
|
x = x._nbsi64;
|
|
}
|
|
print(d,buf.toString());
|
|
|
|
x = this;
|
|
while( x != null ) {
|
|
for( int i=0; i<x._bits.length; i++ )
|
|
System.out.print(Long.toHexString(x._bits[i])+" ");
|
|
x = x._nbsi64;
|
|
System.out.println();
|
|
}
|
|
|
|
if( _copyIdx.get() != 0 || _copyDone.get() != 0 )
|
|
print(d,"_copyIdx="+_copyIdx.get()+" _copyDone="+_copyDone.get()+" _words_to_cpy="+_sum_bits_length);
|
|
if( _new != null ) {
|
|
print(d,"__has_new - ");
|
|
_new.print(d+1);
|
|
}
|
|
}
|
|
}
|
|
}
|