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Revision 1.113 by jsr166, Wed Nov 30 03:31:47 2016 UTC vs.
Revision 1.132 by jsr166, Fri Aug 30 18:05:39 2019 UTC

# Line 1 | Line 1
1   /*
2 < * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
2 > * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
3   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4   *
5   * This code is free software; you can redistribute it and/or modify it
# Line 26 | Line 26
26   package java.util;
27  
28   import java.util.function.Consumer;
29 + import java.util.function.Predicate;
30 + // OPENJDK import jdk.internal.access.SharedSecrets;
31 + import jdk.internal.util.ArraysSupport;
32  
33   /**
34   * An unbounded priority {@linkplain Queue queue} based on a priority heap.
# Line 73 | Line 76 | import java.util.function.Consumer;
76   * ({@code peek}, {@code element}, and {@code size}).
77   *
78   * <p>This class is a member of the
79 < * <a href="{@docRoot}/../technotes/guides/collections/index.html">
79 > * <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
80   * Java Collections Framework</a>.
81   *
82   * @since 1.5
83   * @author Josh Bloch, Doug Lea
84   * @param <E> the type of elements held in this queue
85   */
86 + @SuppressWarnings("unchecked")
87   public class PriorityQueue<E> extends AbstractQueue<E>
88      implements java.io.Serializable {
89  
90 +    // OPENJDK @java.io.Serial
91      private static final long serialVersionUID = -7720805057305804111L;
92  
93      private static final int DEFAULT_INITIAL_CAPACITY = 11;
# Line 186 | Line 191 | public class PriorityQueue<E> extends Ab
191       * @throws NullPointerException if the specified collection or any
192       *         of its elements are null
193       */
189    @SuppressWarnings("unchecked")
194      public PriorityQueue(Collection<? extends E> c) {
195          if (c instanceof SortedSet<?>) {
196              SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
# Line 218 | Line 222 | public class PriorityQueue<E> extends Ab
222       * @throws NullPointerException if the specified priority queue or any
223       *         of its elements are null
224       */
221    @SuppressWarnings("unchecked")
225      public PriorityQueue(PriorityQueue<? extends E> c) {
226          this.comparator = (Comparator<? super E>) c.comparator();
227          initFromPriorityQueue(c);
# Line 237 | Line 240 | public class PriorityQueue<E> extends Ab
240       * @throws NullPointerException if the specified sorted set or any
241       *         of its elements are null
242       */
240    @SuppressWarnings("unchecked")
243      public PriorityQueue(SortedSet<? extends E> c) {
244          this.comparator = (Comparator<? super E>) c.comparator();
245          initElementsFromCollection(c);
246      }
247  
248 +    /** Ensures that queue[0] exists, helping peek() and poll(). */
249 +    private static Object[] ensureNonEmpty(Object[] es) {
250 +        return (es.length > 0) ? es : new Object[1];
251 +    }
252 +
253      private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
254          if (c.getClass() == PriorityQueue.class) {
255 <            this.queue = c.toArray();
255 >            this.queue = ensureNonEmpty(c.toArray());
256              this.size = c.size();
257          } else {
258              initFromCollection(c);
# Line 253 | Line 260 | public class PriorityQueue<E> extends Ab
260      }
261  
262      private void initElementsFromCollection(Collection<? extends E> c) {
263 <        Object[] a = c.toArray();
263 >        Object[] es = c.toArray();
264 >        int len = es.length;
265          // If c.toArray incorrectly doesn't return Object[], copy it.
266 <        if (a.getClass() != Object[].class)
267 <            a = Arrays.copyOf(a, a.length, Object[].class);
260 <        int len = a.length;
266 >        if (es.getClass() != Object[].class)
267 >            es = Arrays.copyOf(es, len, Object[].class);
268          if (len == 1 || this.comparator != null)
269 <            for (Object e : a)
269 >            for (Object e : es)
270                  if (e == null)
271                      throw new NullPointerException();
272 <        this.queue = a;
273 <        this.size = a.length;
272 >        this.queue = ensureNonEmpty(es);
273 >        this.size = len;
274      }
275  
276      /**
# Line 277 | Line 284 | public class PriorityQueue<E> extends Ab
284      }
285  
286      /**
280     * The maximum size of array to allocate.
281     * Some VMs reserve some header words in an array.
282     * Attempts to allocate larger arrays may result in
283     * OutOfMemoryError: Requested array size exceeds VM limit
284     */
285    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
286
287    /**
287       * Increases the capacity of the array.
288       *
289       * @param minCapacity the desired minimum capacity
# Line 292 | Line 291 | public class PriorityQueue<E> extends Ab
291      private void grow(int minCapacity) {
292          int oldCapacity = queue.length;
293          // Double size if small; else grow by 50%
294 <        int newCapacity = oldCapacity + ((oldCapacity < 64) ?
295 <                                         (oldCapacity + 2) :
296 <                                         (oldCapacity >> 1));
297 <        // overflow-conscious code
299 <        if (newCapacity - MAX_ARRAY_SIZE > 0)
300 <            newCapacity = hugeCapacity(minCapacity);
294 >        int newCapacity = ArraysSupport.newLength(oldCapacity,
295 >                minCapacity - oldCapacity, /* minimum growth */
296 >                oldCapacity < 64 ? oldCapacity + 2 : oldCapacity >> 1
297 >                                           /* preferred growth */);
298          queue = Arrays.copyOf(queue, newCapacity);
299      }
300  
304    private static int hugeCapacity(int minCapacity) {
305        if (minCapacity < 0) // overflow
306            throw new OutOfMemoryError();
307        return (minCapacity > MAX_ARRAY_SIZE) ?
308            Integer.MAX_VALUE :
309            MAX_ARRAY_SIZE;
310    }
311
301      /**
302       * Inserts the specified element into this priority queue.
303       *
# Line 343 | Line 332 | public class PriorityQueue<E> extends Ab
332          return true;
333      }
334  
346    @SuppressWarnings("unchecked")
335      public E peek() {
336 <        return (size == 0) ? null : (E) queue[0];
336 >        return (E) queue[0];
337      }
338  
339      private int indexOf(Object o) {
340          if (o != null) {
341 <            for (int i = 0; i < size; i++)
342 <                if (o.equals(queue[i]))
341 >            final Object[] es = queue;
342 >            for (int i = 0, n = size; i < n; i++)
343 >                if (o.equals(es[i]))
344                      return i;
345          }
346          return -1;
# Line 379 | Line 368 | public class PriorityQueue<E> extends Ab
368      }
369  
370      /**
371 <     * Version of remove using reference equality, not equals.
383 <     * Needed by iterator.remove.
371 >     * Identity-based version for use in Itr.remove.
372       *
373       * @param o element to be removed from this queue, if present
386     * @return {@code true} if removed
374       */
375 <    boolean removeEq(Object o) {
376 <        for (int i = 0; i < size; i++) {
377 <            if (o == queue[i]) {
375 >    void removeEq(Object o) {
376 >        final Object[] es = queue;
377 >        for (int i = 0, n = size; i < n; i++) {
378 >            if (o == es[i]) {
379                  removeAt(i);
380 <                return true;
380 >                break;
381              }
382          }
395        return false;
383      }
384  
385      /**
# Line 460 | Line 447 | public class PriorityQueue<E> extends Ab
447       *         this queue
448       * @throws NullPointerException if the specified array is null
449       */
463    @SuppressWarnings("unchecked")
450      public <T> T[] toArray(T[] a) {
451          final int size = this.size;
452          if (a.length < size)
# Line 522 | Line 508 | public class PriorityQueue<E> extends Ab
508           */
509          private int expectedModCount = modCount;
510  
511 +        Itr() {}                        // prevent access constructor creation
512 +
513          public boolean hasNext() {
514              return cursor < size ||
515                  (forgetMeNot != null && !forgetMeNot.isEmpty());
516          }
517  
530        @SuppressWarnings("unchecked")
518          public E next() {
519              if (expectedModCount != modCount)
520                  throw new ConcurrentModificationException();
# Line 575 | Line 562 | public class PriorityQueue<E> extends Ab
562       */
563      public void clear() {
564          modCount++;
565 <        for (int i = 0; i < size; i++)
566 <            queue[i] = null;
565 >        final Object[] es = queue;
566 >        for (int i = 0, n = size; i < n; i++)
567 >            es[i] = null;
568          size = 0;
569      }
570  
583    @SuppressWarnings("unchecked")
571      public E poll() {
572 <        if (size == 0)
573 <            return null;
574 <        int s = --size;
575 <        modCount++;
576 <        E result = (E) queue[0];
577 <        E x = (E) queue[s];
578 <        queue[s] = null;
579 <        if (s != 0)
580 <            siftDown(0, x);
572 >        final Object[] es;
573 >        final E result;
574 >
575 >        if ((result = (E) ((es = queue)[0])) != null) {
576 >            modCount++;
577 >            final int n;
578 >            final E x = (E) es[(n = --size)];
579 >            es[n] = null;
580 >            if (n > 0) {
581 >                final Comparator<? super E> cmp;
582 >                if ((cmp = comparator) == null)
583 >                    siftDownComparable(0, x, es, n);
584 >                else
585 >                    siftDownUsingComparator(0, x, es, n, cmp);
586 >            }
587 >        }
588          return result;
589      }
590  
# Line 606 | Line 600 | public class PriorityQueue<E> extends Ab
600       * position before i. This fact is used by iterator.remove so as to
601       * avoid missing traversing elements.
602       */
609    @SuppressWarnings("unchecked")
603      E removeAt(int i) {
604          // assert i >= 0 && i < size;
605 +        final Object[] es = queue;
606          modCount++;
607          int s = --size;
608          if (s == i) // removed last element
609 <            queue[i] = null;
609 >            es[i] = null;
610          else {
611 <            E moved = (E) queue[s];
612 <            queue[s] = null;
611 >            E moved = (E) es[s];
612 >            es[s] = null;
613              siftDown(i, moved);
614 <            if (queue[i] == moved) {
614 >            if (es[i] == moved) {
615                  siftUp(i, moved);
616 <                if (queue[i] != moved)
616 >                if (es[i] != moved)
617                      return moved;
618              }
619          }
# Line 631 | Line 625 | public class PriorityQueue<E> extends Ab
625       * promoting x up the tree until it is greater than or equal to
626       * its parent, or is the root.
627       *
628 <     * To simplify and speed up coercions and comparisons. the
628 >     * To simplify and speed up coercions and comparisons, the
629       * Comparable and Comparator versions are separated into different
630       * methods that are otherwise identical. (Similarly for siftDown.)
631       *
# Line 640 | Line 634 | public class PriorityQueue<E> extends Ab
634       */
635      private void siftUp(int k, E x) {
636          if (comparator != null)
637 <            siftUpUsingComparator(k, x);
637 >            siftUpUsingComparator(k, x, queue, comparator);
638          else
639 <            siftUpComparable(k, x);
639 >            siftUpComparable(k, x, queue);
640      }
641  
642 <    @SuppressWarnings("unchecked")
643 <    private void siftUpComparable(int k, E x) {
650 <        Comparable<? super E> key = (Comparable<? super E>) x;
642 >    private static <T> void siftUpComparable(int k, T x, Object[] es) {
643 >        Comparable<? super T> key = (Comparable<? super T>) x;
644          while (k > 0) {
645              int parent = (k - 1) >>> 1;
646 <            Object e = queue[parent];
647 <            if (key.compareTo((E) e) >= 0)
646 >            Object e = es[parent];
647 >            if (key.compareTo((T) e) >= 0)
648                  break;
649 <            queue[k] = e;
649 >            es[k] = e;
650              k = parent;
651          }
652 <        queue[k] = key;
652 >        es[k] = key;
653      }
654  
655 <    @SuppressWarnings("unchecked")
656 <    private void siftUpUsingComparator(int k, E x) {
655 >    private static <T> void siftUpUsingComparator(
656 >        int k, T x, Object[] es, Comparator<? super T> cmp) {
657          while (k > 0) {
658              int parent = (k - 1) >>> 1;
659 <            Object e = queue[parent];
660 <            if (comparator.compare(x, (E) e) >= 0)
659 >            Object e = es[parent];
660 >            if (cmp.compare(x, (T) e) >= 0)
661                  break;
662 <            queue[k] = e;
662 >            es[k] = e;
663              k = parent;
664          }
665 <        queue[k] = x;
665 >        es[k] = x;
666      }
667  
668      /**
# Line 682 | Line 675 | public class PriorityQueue<E> extends Ab
675       */
676      private void siftDown(int k, E x) {
677          if (comparator != null)
678 <            siftDownUsingComparator(k, x);
678 >            siftDownUsingComparator(k, x, queue, size, comparator);
679          else
680 <            siftDownComparable(k, x);
680 >            siftDownComparable(k, x, queue, size);
681      }
682  
683 <    @SuppressWarnings("unchecked")
684 <    private void siftDownComparable(int k, E x) {
685 <        Comparable<? super E> key = (Comparable<? super E>)x;
686 <        int half = size >>> 1;        // loop while a non-leaf
683 >    private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
684 >        // assert n > 0;
685 >        Comparable<? super T> key = (Comparable<? super T>)x;
686 >        int half = n >>> 1;           // loop while a non-leaf
687          while (k < half) {
688              int child = (k << 1) + 1; // assume left child is least
689 <            Object c = queue[child];
689 >            Object c = es[child];
690              int right = child + 1;
691 <            if (right < size &&
692 <                ((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
693 <                c = queue[child = right];
694 <            if (key.compareTo((E) c) <= 0)
691 >            if (right < n &&
692 >                ((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
693 >                c = es[child = right];
694 >            if (key.compareTo((T) c) <= 0)
695                  break;
696 <            queue[k] = c;
696 >            es[k] = c;
697              k = child;
698          }
699 <        queue[k] = key;
699 >        es[k] = key;
700      }
701  
702 <    @SuppressWarnings("unchecked")
703 <    private void siftDownUsingComparator(int k, E x) {
704 <        int half = size >>> 1;
702 >    private static <T> void siftDownUsingComparator(
703 >        int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
704 >        // assert n > 0;
705 >        int half = n >>> 1;
706          while (k < half) {
707              int child = (k << 1) + 1;
708 <            Object c = queue[child];
708 >            Object c = es[child];
709              int right = child + 1;
710 <            if (right < size &&
711 <                comparator.compare((E) c, (E) queue[right]) > 0)
712 <                c = queue[child = right];
719 <            if (comparator.compare(x, (E) c) <= 0)
710 >            if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
711 >                c = es[child = right];
712 >            if (cmp.compare(x, (T) c) <= 0)
713                  break;
714 <            queue[k] = c;
714 >            es[k] = c;
715              k = child;
716          }
717 <        queue[k] = x;
717 >        es[k] = x;
718      }
719  
720      /**
# Line 729 | Line 722 | public class PriorityQueue<E> extends Ab
722       * assuming nothing about the order of the elements prior to the call.
723       * This classic algorithm due to Floyd (1964) is known to be O(size).
724       */
732    @SuppressWarnings("unchecked")
725      private void heapify() {
726 <        for (int i = (size >>> 1) - 1; i >= 0; i--)
727 <            siftDown(i, (E) queue[i]);
726 >        final Object[] es = queue;
727 >        int n = size, i = (n >>> 1) - 1;
728 >        final Comparator<? super E> cmp;
729 >        if ((cmp = comparator) == null)
730 >            for (; i >= 0; i--)
731 >                siftDownComparable(i, (E) es[i], es, n);
732 >        else
733 >            for (; i >= 0; i--)
734 >                siftDownUsingComparator(i, (E) es[i], es, n, cmp);
735      }
736  
737      /**
# Line 757 | Line 756 | public class PriorityQueue<E> extends Ab
756       *             emitted (int), followed by all of its elements
757       *             (each an {@code Object}) in the proper order.
758       */
759 +    // OPENJDK @java.io.Serial
760      private void writeObject(java.io.ObjectOutputStream s)
761          throws java.io.IOException {
762          // Write out element count, and any hidden stuff
# Line 766 | Line 766 | public class PriorityQueue<E> extends Ab
766          s.writeInt(Math.max(2, size + 1));
767  
768          // Write out all elements in the "proper order".
769 <        for (int i = 0; i < size; i++)
770 <            s.writeObject(queue[i]);
769 >        final Object[] es = queue;
770 >        for (int i = 0, n = size; i < n; i++)
771 >            s.writeObject(es[i]);
772      }
773  
774      /**
# Line 779 | Line 780 | public class PriorityQueue<E> extends Ab
780       *         could not be found
781       * @throws java.io.IOException if an I/O error occurs
782       */
783 +    // OPENJDK @java.io.Serial
784      private void readObject(java.io.ObjectInputStream s)
785          throws java.io.IOException, ClassNotFoundException {
786          // Read in size, and any hidden stuff
# Line 787 | Line 789 | public class PriorityQueue<E> extends Ab
789          // Read in (and discard) array length
790          s.readInt();
791  
792 <        queue = new Object[size];
792 >        jsr166.Platform.checkArray(s, Object[].class, size);
793 >        final Object[] es = queue = new Object[Math.max(size, 1)];
794  
795          // Read in all elements.
796 <        for (int i = 0; i < size; i++)
797 <            queue[i] = s.readObject();
796 >        for (int i = 0, n = size; i < n; i++)
797 >            es[i] = s.readObject();
798  
799          // Elements are guaranteed to be in "proper order", but the
800          // spec has never explained what that might be.
# Line 817 | Line 820 | public class PriorityQueue<E> extends Ab
820      }
821  
822      final class PriorityQueueSpliterator implements Spliterator<E> {
820        /*
821         * This is very similar to ArrayList Spliterator, except for
822         * extra null checks.
823         */
823          private int index;            // current index, modified on advance/split
824          private int fence;            // -1 until first use
825          private int expectedModCount; // initialized when fence set
# Line 847 | Line 846 | public class PriorityQueue<E> extends Ab
846                  new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
847          }
848  
850        @SuppressWarnings("unchecked")
849          public void forEachRemaining(Consumer<? super E> action) {
852            int i, hi, mc; // hoist accesses and checks from loop
853            final Object[] a;
850              if (action == null)
851                  throw new NullPointerException();
852 <            if ((a = queue) != null) {
853 <                if ((hi = fence) < 0) {
854 <                    mc = modCount;
855 <                    hi = size;
856 <                }
857 <                else
858 <                    mc = expectedModCount;
863 <                if ((i = index) >= 0 && (index = hi) <= a.length) {
864 <                    for (E e;; ++i) {
865 <                        if (i < hi) {
866 <                            if ((e = (E) a[i]) == null) // must be CME
867 <                                break;
868 <                            action.accept(e);
869 <                        }
870 <                        else if (modCount != mc)
871 <                            break;
872 <                        else
873 <                            return;
874 <                    }
875 <                }
852 >            if (fence < 0) { fence = size; expectedModCount = modCount; }
853 >            final Object[] es = queue;
854 >            int i, hi; E e;
855 >            for (i = index, index = hi = fence; i < hi; i++) {
856 >                if ((e = (E) es[i]) == null)
857 >                    break;      // must be CME
858 >                action.accept(e);
859              }
860 <            throw new ConcurrentModificationException();
860 >            if (modCount != expectedModCount)
861 >                throw new ConcurrentModificationException();
862          }
863  
864          public boolean tryAdvance(Consumer<? super E> action) {
865              if (action == null)
866                  throw new NullPointerException();
867 <            int hi = getFence(), lo = index;
868 <            if (lo >= 0 && lo < hi) {
869 <                index = lo + 1;
870 <                @SuppressWarnings("unchecked") E e = (E)queue[lo];
871 <                if (e == null)
867 >            if (fence < 0) { fence = size; expectedModCount = modCount; }
868 >            int i;
869 >            if ((i = index) < fence) {
870 >                index = i + 1;
871 >                E e;
872 >                if ((e = (E) queue[i]) == null
873 >                    || modCount != expectedModCount)
874                      throw new ConcurrentModificationException();
875                  action.accept(e);
890                if (modCount != expectedModCount)
891                    throw new ConcurrentModificationException();
876                  return true;
877              }
878              return false;
# Line 902 | Line 886 | public class PriorityQueue<E> extends Ab
886              return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
887          }
888      }
889 +
890 +    /**
891 +     * @throws NullPointerException {@inheritDoc}
892 +     */
893 +    public boolean removeIf(Predicate<? super E> filter) {
894 +        Objects.requireNonNull(filter);
895 +        return bulkRemove(filter);
896 +    }
897 +
898 +    /**
899 +     * @throws NullPointerException {@inheritDoc}
900 +     */
901 +    public boolean removeAll(Collection<?> c) {
902 +        Objects.requireNonNull(c);
903 +        return bulkRemove(e -> c.contains(e));
904 +    }
905 +
906 +    /**
907 +     * @throws NullPointerException {@inheritDoc}
908 +     */
909 +    public boolean retainAll(Collection<?> c) {
910 +        Objects.requireNonNull(c);
911 +        return bulkRemove(e -> !c.contains(e));
912 +    }
913 +
914 +    // A tiny bit set implementation
915 +
916 +    private static long[] nBits(int n) {
917 +        return new long[((n - 1) >> 6) + 1];
918 +    }
919 +    private static void setBit(long[] bits, int i) {
920 +        bits[i >> 6] |= 1L << i;
921 +    }
922 +    private static boolean isClear(long[] bits, int i) {
923 +        return (bits[i >> 6] & (1L << i)) == 0;
924 +    }
925 +
926 +    /** Implementation of bulk remove methods. */
927 +    private boolean bulkRemove(Predicate<? super E> filter) {
928 +        final int expectedModCount = ++modCount;
929 +        final Object[] es = queue;
930 +        final int end = size;
931 +        int i;
932 +        // Optimize for initial run of survivors
933 +        for (i = 0; i < end && !filter.test((E) es[i]); i++)
934 +            ;
935 +        if (i >= end) {
936 +            if (modCount != expectedModCount)
937 +                throw new ConcurrentModificationException();
938 +            return false;
939 +        }
940 +        // Tolerate predicates that reentrantly access the collection for
941 +        // read (but writers still get CME), so traverse once to find
942 +        // elements to delete, a second pass to physically expunge.
943 +        final int beg = i;
944 +        final long[] deathRow = nBits(end - beg);
945 +        deathRow[0] = 1L;   // set bit 0
946 +        for (i = beg + 1; i < end; i++)
947 +            if (filter.test((E) es[i]))
948 +                setBit(deathRow, i - beg);
949 +        if (modCount != expectedModCount)
950 +            throw new ConcurrentModificationException();
951 +        int w = beg;
952 +        for (i = beg; i < end; i++)
953 +            if (isClear(deathRow, i - beg))
954 +                es[w++] = es[i];
955 +        for (i = size = w; i < end; i++)
956 +            es[i] = null;
957 +        heapify();
958 +        return true;
959 +    }
960 +
961 +    /**
962 +     * @throws NullPointerException {@inheritDoc}
963 +     */
964 +    public void forEach(Consumer<? super E> action) {
965 +        Objects.requireNonNull(action);
966 +        final int expectedModCount = modCount;
967 +        final Object[] es = queue;
968 +        for (int i = 0, n = size; i < n; i++)
969 +            action.accept((E) es[i]);
970 +        if (expectedModCount != modCount)
971 +            throw new ConcurrentModificationException();
972 +    }
973   }

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