--- jsr166/src/main/java/util/ArrayList.java 2016/11/13 21:07:40 1.41 +++ jsr166/src/main/java/util/ArrayList.java 2016/12/21 05:15:36 1.49 @@ -578,8 +578,9 @@ public class ArrayList extends Abstra */ public void clear() { modCount++; - Arrays.fill(elementData, 0, size, null); - size = 0; + final Object[] es = elementData; + for (int to = size, i = size = 0; i < to; i++) + es[i] = null; } /** @@ -669,13 +670,17 @@ public class ArrayList extends Abstra outOfBoundsMsg(fromIndex, toIndex)); } modCount++; - final Object[] es = elementData; - final int oldSize = size; - System.arraycopy(es, toIndex, es, fromIndex, oldSize - toIndex); - Arrays.fill(es, size -= (toIndex - fromIndex), oldSize, null); + shiftTailOverGap(elementData, fromIndex, toIndex); // checkInvariants(); } + /** Erases the gap from lo to hi, by sliding down following elements. */ + private void shiftTailOverGap(Object[] es, int lo, int hi) { + System.arraycopy(es, hi, es, lo, size - hi); + for (int to = size, i = (size -= hi - lo); i < to; i++) + es[i] = null; + } + /** * A version of rangeCheck used by add and addAll. */ @@ -761,10 +766,8 @@ public class ArrayList extends Abstra w += end - r; throw ex; } finally { - final int oldSize = size, deleted = end - w; - modCount += deleted; - System.arraycopy(es, end, es, w, oldSize - end); - Arrays.fill(es, size -= deleted, oldSize, null); + modCount += end - w; + shiftTailOverGap(es, w, end); } } // checkInvariants(); @@ -772,15 +775,17 @@ public class ArrayList extends Abstra } /** - * Save the state of the {@code ArrayList} instance to a stream (that - * is, serialize it). + * Saves the state of the {@code ArrayList} instance to a stream + * (that is, serializes it). * + * @param s the stream + * @throws java.io.IOException if an I/O error occurs * @serialData The length of the array backing the {@code ArrayList} * instance is emitted (int), followed by all of its elements * (each an {@code Object}) in the proper order. */ private void writeObject(java.io.ObjectOutputStream s) - throws java.io.IOException{ + throws java.io.IOException { // Write out element count, and any hidden stuff int expectedModCount = modCount; s.defaultWriteObject(); @@ -799,8 +804,12 @@ public class ArrayList extends Abstra } /** - * Reconstitute the {@code ArrayList} instance from a stream (that is, - * deserialize it). + * Reconstitutes the {@code ArrayList} instance from a stream (that is, + * deserializes it). + * @param s the stream + * @throws ClassNotFoundException if the class of a serialized object + * could not be found + * @throws java.io.IOException if an I/O error occurs */ private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { @@ -912,25 +921,21 @@ public class ArrayList extends Abstra } @Override - @SuppressWarnings("unchecked") - public void forEachRemaining(Consumer consumer) { - Objects.requireNonNull(consumer); + public void forEachRemaining(Consumer action) { + Objects.requireNonNull(action); final int size = ArrayList.this.size; int i = cursor; - if (i >= size) { - return; - } - final Object[] elementData = ArrayList.this.elementData; - if (i >= elementData.length) { - throw new ConcurrentModificationException(); - } - while (i != size && modCount == expectedModCount) { - consumer.accept((E) elementData[i++]); + if (i < size) { + final Object[] es = elementData; + if (i >= es.length) + throw new ConcurrentModificationException(); + for (; i < size && modCount == expectedModCount; i++) + action.accept(elementAt(es, i)); + // update once at end to reduce heap write traffic + cursor = i; + lastRet = i - 1; + checkForComodification(); } - // update once at end of iteration to reduce heap write traffic - cursor = i; - lastRet = i - 1; - checkForComodification(); } final void checkForComodification() { @@ -1191,24 +1196,21 @@ public class ArrayList extends Abstra return (E) elementData[offset + (lastRet = i)]; } - @SuppressWarnings("unchecked") - public void forEachRemaining(Consumer consumer) { - Objects.requireNonNull(consumer); + public void forEachRemaining(Consumer action) { + Objects.requireNonNull(action); final int size = SubList.this.size; int i = cursor; - if (i >= size) { - return; - } - final Object[] elementData = root.elementData; - if (offset + i >= elementData.length) { - throw new ConcurrentModificationException(); - } - while (i != size && modCount == expectedModCount) { - consumer.accept((E) elementData[offset + (i++)]); + if (i < size) { + final Object[] es = root.elementData; + if (offset + i >= es.length) + throw new ConcurrentModificationException(); + for (; i < size && modCount == expectedModCount; i++) + action.accept(elementAt(es, offset + i)); + // update once at end to reduce heap write traffic + cursor = i; + lastRet = i - 1; + checkForComodification(); } - // update once at end of iteration to reduce heap write traffic - lastRet = cursor = i; - checkForComodification(); } public int nextIndex() { @@ -1298,9 +1300,8 @@ public class ArrayList extends Abstra public Spliterator spliterator() { checkForComodification(); - // ArrayListSpliterator is not used because late-binding logic - // is different here - return new Spliterator<>() { + // ArrayListSpliterator not used here due to late-binding + return new Spliterator() { private int index = offset; // current index, modified on advance/split private int fence = -1; // -1 until used; then one past last index private int expectedModCount; // initialized when fence set @@ -1314,12 +1315,11 @@ public class ArrayList extends Abstra return hi; } - public ArrayListSpliterator trySplit() { + public ArrayList.ArrayListSpliterator trySplit() { int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; - // ArrayListSpliterator could be used here as the source is already bound + // ArrayListSpliterator can be used here as the source is already bound return (lo >= mid) ? null : // divide range in half unless too small - new ArrayListSpliterator<>(root, lo, index = mid, - expectedModCount); + root.new ArrayListSpliterator(lo, index = mid, expectedModCount); } public boolean tryAdvance(Consumer action) { @@ -1361,7 +1361,7 @@ public class ArrayList extends Abstra } public long estimateSize() { - return (long) (getFence() - index); + return getFence() - index; } public int characteristics() { @@ -1371,6 +1371,9 @@ public class ArrayList extends Abstra } } + /** + * @throws NullPointerException {@inheritDoc} + */ @Override public void forEach(Consumer action) { Objects.requireNonNull(action); @@ -1398,11 +1401,11 @@ public class ArrayList extends Abstra */ @Override public Spliterator spliterator() { - return new ArrayListSpliterator<>(this, 0, -1, 0); + return new ArrayListSpliterator(0, -1, 0); } /** Index-based split-by-two, lazily initialized Spliterator */ - static final class ArrayListSpliterator implements Spliterator { + final class ArrayListSpliterator implements Spliterator { /* * If ArrayLists were immutable, or structurally immutable (no @@ -1436,15 +1439,12 @@ public class ArrayList extends Abstra * these streamlinings. */ - private final ArrayList list; private int index; // current index, modified on advance/split private int fence; // -1 until used; then one past last index private int expectedModCount; // initialized when fence set - /** Create new spliterator covering the given range */ - ArrayListSpliterator(ArrayList list, int origin, int fence, - int expectedModCount) { - this.list = list; // OK if null unless traversed + /** Creates new spliterator covering the given range. */ + ArrayListSpliterator(int origin, int fence, int expectedModCount) { this.index = origin; this.fence = fence; this.expectedModCount = expectedModCount; @@ -1452,23 +1452,17 @@ public class ArrayList extends Abstra private int getFence() { // initialize fence to size on first use int hi; // (a specialized variant appears in method forEach) - ArrayList lst; if ((hi = fence) < 0) { - if ((lst = list) == null) - hi = fence = 0; - else { - expectedModCount = lst.modCount; - hi = fence = lst.size; - } + expectedModCount = modCount; + hi = fence = size; } return hi; } - public ArrayListSpliterator trySplit() { + public ArrayListSpliterator trySplit() { int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; return (lo >= mid) ? null : // divide range in half unless too small - new ArrayListSpliterator<>(list, lo, index = mid, - expectedModCount); + new ArrayListSpliterator(lo, index = mid, expectedModCount); } public boolean tryAdvance(Consumer action) { @@ -1477,9 +1471,9 @@ public class ArrayList extends Abstra int hi = getFence(), i = index; if (i < hi) { index = i + 1; - @SuppressWarnings("unchecked") E e = (E)list.elementData[i]; + @SuppressWarnings("unchecked") E e = (E)elementData[i]; action.accept(e); - if (list.modCount != expectedModCount) + if (modCount != expectedModCount) throw new ConcurrentModificationException(); return true; } @@ -1488,13 +1482,13 @@ public class ArrayList extends Abstra public void forEachRemaining(Consumer action) { int i, hi, mc; // hoist accesses and checks from loop - ArrayList lst; Object[] a; + Object[] a; if (action == null) throw new NullPointerException(); - if ((lst = list) != null && (a = lst.elementData) != null) { + if ((a = elementData) != null) { if ((hi = fence) < 0) { - mc = lst.modCount; - hi = lst.size; + mc = modCount; + hi = size; } else mc = expectedModCount; @@ -1503,7 +1497,7 @@ public class ArrayList extends Abstra @SuppressWarnings("unchecked") E e = (E) a[i]; action.accept(e); } - if (lst.modCount == mc) + if (modCount == mc) return; } } @@ -1511,7 +1505,7 @@ public class ArrayList extends Abstra } public long estimateSize() { - return (long) (getFence() - index); + return getFence() - index; } public int characteristics() { @@ -1531,27 +1525,29 @@ public class ArrayList extends Abstra return (bits[i >> 6] & (1L << i)) == 0; } + /** + * @throws NullPointerException {@inheritDoc} + */ @Override public boolean removeIf(Predicate filter) { return removeIf(filter, 0, size); } - boolean removeIf(Predicate filter, - final int from, final int end) { + /** + * Removes all elements satisfying the given predicate, from index + * i (inclusive) to index end (exclusive). + */ + boolean removeIf(Predicate filter, int i, final int end) { Objects.requireNonNull(filter); int expectedModCount = modCount; final Object[] es = elementData; - final boolean modified; - int i; // Optimize for initial run of survivors - for (i = from; i < end && !filter.test(elementAt(es, i)); i++) + for (; i < end && !filter.test(elementAt(es, i)); i++) ; // Tolerate predicates that reentrantly access the collection for // read (but writers still get CME), so traverse once to find // elements to delete, a second pass to physically expunge. - if (modified = (i < end)) { - expectedModCount++; - modCount++; + if (i < end) { final int beg = i; final long[] deathRow = nBits(end - beg); deathRow[0] = 1L; // set bit 0 @@ -1560,18 +1556,21 @@ public class ArrayList extends Abstra setBit(deathRow, i - beg); if (modCount != expectedModCount) throw new ConcurrentModificationException(); + expectedModCount++; + modCount++; int w = beg; for (i = beg; i < end; i++) if (isClear(deathRow, i - beg)) es[w++] = es[i]; - final int oldSize = size; - System.arraycopy(es, end, es, w, oldSize - end); - Arrays.fill(es, size -= (end - w), oldSize, null); + shiftTailOverGap(es, w, end); + // checkInvariants(); + return true; + } else { + if (modCount != expectedModCount) + throw new ConcurrentModificationException(); + // checkInvariants(); + return false; } - if (modCount != expectedModCount) - throw new ConcurrentModificationException(); - // checkInvariants(); - return modified; } @Override