jsr166e.extra.ReadMostlyVector Maven / Gradle / Ivy
/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*/
package jsr166e.extra;
import jsr166e.StampedLock;
import java.util.*;
/**
* A class with the same methods and array-based characteristics as
* {@link java.util.Vector} but with reduced contention and improved
* throughput when invocations of read-only methods by multiple
* threads are most common.
*
* The iterators returned by this class's {@link #iterator()
* iterator} and {@link #listIterator(int) listIterator} methods are
* best-effort in the presence of concurrent modifications, and do
* NOT throw {@link ConcurrentModificationException}. An
* iterator's {@code next()} method returns consecutive elements as
* they appear in the underlying array upon each access. Alternatively,
* method {@link #snapshotIterator} may be used for deterministic
* traversals, at the expense of making a copy, and unavailability of
* method {@code Iterator.remove}.
*
*
Otherwise, this class supports all methods, under the same
* documented specifications, as {@code Vector}. Consult {@link
* java.util.Vector} for detailed specifications. Additionally, this
* class provides methods {@link #addIfAbsent} and {@link
* #addAllAbsent}.
*
* @author Doug Lea
*/
public class ReadMostlyVector
implements List, RandomAccess, Cloneable, java.io.Serializable {
private static final long serialVersionUID = 8673264195747942595L;
/*
* This class exists mainly as a vehicle to exercise various
* constructions using SequenceLocks. Read-only methods
* take one of a few forms:
*
* Short methods,including get(index), continually retry obtaining
* a snapshot of array, count, and element, using sequence number
* to validate.
*
* Methods that are potentially O(n) (or worse) try once in
* read-only mode, and then lock. When in read-only mode, they
* validate only at the end of an array scan unless the element is
* actually used (for example, as an argument of method equals).
*
* We rely on some invariants that are always true, even for field
* reads in read-only mode that have not yet been validated:
* - array != null
* - count >= 0
*/
/**
* The maximum size of array to allocate.
* See CopyOnWriteArrayList for explanation.
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
// fields are non-private to simplify nested class access
Object[] array;
final StampedLock lock;
int count;
final int capacityIncrement;
/**
* Creates an empty vector with the given initial capacity and
* capacity increment.
*
* @param initialCapacity the initial capacity of the underlying array
* @param capacityIncrement if non-zero, the number to
* add when resizing to accommodate additional elements.
* If zero, the array size is doubled when resized.
*
* @throws IllegalArgumentException if initial capacity is negative
*/
public ReadMostlyVector(int initialCapacity, int capacityIncrement) {
super();
if (initialCapacity < 0)
throw new IllegalArgumentException("Illegal Capacity: "+
initialCapacity);
this.array = new Object[initialCapacity];
this.capacityIncrement = capacityIncrement;
this.lock = new StampedLock();
}
/**
* Creates an empty vector with the given initial capacity.
*
* @param initialCapacity the initial capacity of the underlying array
* @throws IllegalArgumentException if initial capacity is negative
*/
public ReadMostlyVector(int initialCapacity) {
this(initialCapacity, 0);
}
/**
* Creates an empty vector.
*/
public ReadMostlyVector() {
this.capacityIncrement = 0;
this.lock = new StampedLock();
}
/**
* Creates a vector containing the elements of the specified
* collection, in the order they are returned by the collection's
* iterator.
*
* @param c the collection of initially held elements
* @throws NullPointerException if the specified collection is null
*/
public ReadMostlyVector(Collection c) {
Object[] elements = c.toArray();
// c.toArray might (incorrectly) not return Object[] (see 6260652)
if (elements.getClass() != Object[].class)
elements = Arrays.copyOf(elements, elements.length, Object[].class);
this.array = elements;
this.count = elements.length;
this.capacityIncrement = 0;
this.lock = new StampedLock();
}
// internal constructor for clone
ReadMostlyVector(Object[] array, int count, int capacityIncrement) {
this.array = array;
this.count = count;
this.capacityIncrement = capacityIncrement;
this.lock = new StampedLock();
}
static final int INITIAL_CAP = 16;
// For explanation, see CopyOnWriteArrayList
final Object[] grow(int minCapacity) {
Object[] items;
int newCapacity;
if ((items = array) == null)
newCapacity = INITIAL_CAP;
else {
int oldCapacity = array.length;
newCapacity = oldCapacity + ((capacityIncrement > 0) ?
capacityIncrement : oldCapacity);
}
if (newCapacity - minCapacity < 0)
newCapacity = minCapacity;
if (newCapacity - MAX_ARRAY_SIZE > 0) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
else if (minCapacity > MAX_ARRAY_SIZE)
newCapacity = Integer.MAX_VALUE;
else
newCapacity = MAX_ARRAY_SIZE;
}
return array = ((items == null) ?
new Object[newCapacity] :
Arrays.copyOf(items, newCapacity));
}
/*
* Internal versions of most base functionality, wrapped
* in different ways from public methods from this class
* as well as sublist and iterator classes.
*/
static int findFirstIndex(Object[] items, Object x, int index, int fence) {
int len;
if (items != null && (len = items.length) > 0) {
int start = (index < 0) ? 0 : index;
int bound = (fence < len) ? fence : len;
for (int i = start; i < bound; ++i) {
Object e = items[i];
if ((x == null) ? e == null : x.equals(e))
return i;
}
}
return -1;
}
static int findLastIndex(Object[] items, Object x, int index, int origin) {
int len;
if (items != null && (len = items.length) > 0) {
int last = (index < len) ? index : len - 1;
int start = (origin < 0) ? 0 : origin;
for (int i = last; i >= start; --i) {
Object e = items[i];
if ((x == null) ? e == null : x.equals(e))
return i;
}
}
return -1;
}
final void rawAdd(E e) {
int n = count;
Object[] items = array;
if (items == null || n >= items.length)
items = grow(n + 1);
items[n] = e;
count = n + 1;
}
final void rawAddAt(int index, E e) {
int n = count;
Object[] items = array;
if (index > n)
throw new ArrayIndexOutOfBoundsException(index);
if (items == null || n >= items.length)
items = grow(n + 1);
if (index < n)
System.arraycopy(items, index, items, index + 1, n - index);
items[index] = e;
count = n + 1;
}
final boolean rawAddAllAt(int index, Object[] elements) {
int n = count;
Object[] items = array;
if (index < 0 || index > n)
throw new ArrayIndexOutOfBoundsException(index);
int len = elements.length;
if (len == 0)
return false;
int newCount = n + len;
if (items == null || newCount >= items.length)
items = grow(newCount);
int mv = n - index;
if (mv > 0)
System.arraycopy(items, index, items, index + len, mv);
System.arraycopy(elements, 0, items, index, len);
count = newCount;
return true;
}
final boolean rawRemoveAt(int index) {
int n = count - 1;
Object[] items = array;
if (items == null || index < 0 || index > n)
return false;
int mv = n - index;
if (mv > 0)
System.arraycopy(items, index + 1, items, index, mv);
items[n] = null;
count = n;
return true;
}
/**
* Internal version of removeAll for lists and sublists. In this
* and other similar methods below, the bound argument is, if
* non-negative, the purported upper bound of a list/sublist, or
* is left negative if the bound should be determined via count
* field under lock.
*/
final boolean lockedRemoveAll(Collection c, int origin, int bound) {
boolean removed = false;
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
int n = count;
int fence = bound < 0 || bound > n ? n : bound;
if (origin >= 0 && origin < fence) {
for (Object x : c) {
while (rawRemoveAt(findFirstIndex(array, x, origin, fence)))
removed = true;
}
}
} finally {
lock.unlockWrite(stamp);
}
return removed;
}
final boolean lockedRetainAll(Collection c, int origin, int bound) {
final StampedLock lock = this.lock;
boolean removed = false;
if (c != this) {
long stamp = lock.writeLock();
try {
Object[] items;
int i, n;
if ((items = array) != null && (n = count) > 0 &&
n < items.length && (i = origin) >= 0) {
int fence = bound < 0 || bound > n ? n : bound;
while (i < fence) {
if (c.contains(items[i]))
++i;
else {
--fence;
int mv = --n - i;
if (mv > 0)
System.arraycopy(items, i + 1, items, i, mv);
}
}
if (count != n) {
count = n;
removed = true;
}
}
} finally {
lock.unlockWrite(stamp);
}
}
return removed;
}
final void internalClear(int origin, int bound) {
Object[] items;
int n, len;
if ((items = array) != null && (len = items.length) > 0) {
if (origin < 0)
origin = 0;
if ((n = count) > len)
n = len;
int fence = bound < 0 || bound > n ? n : bound;
int removed = fence - origin;
int newCount = n - removed;
int mv = n - (origin + removed);
if (mv > 0)
System.arraycopy(items, origin + removed, items, origin, mv);
for (int i = n; i < newCount; ++i)
items[i] = null;
count = newCount;
}
}
final boolean internalContainsAll(Collection c, int origin, int bound) {
Object[] items;
int n, len;
if ((items = array) != null && (len = items.length) > 0) {
if (origin < 0)
origin = 0;
if ((n = count) > len)
n = len;
int fence = bound < 0 || bound > n ? n : bound;
for (Object e : c) {
if (findFirstIndex(items, e, origin, fence) < 0)
return false;
}
}
else if (!c.isEmpty())
return false;
return true;
}
final boolean internalEquals(List list, int origin, int bound) {
Object[] items;
int n, len;
if ((items = array) != null && (len = items.length) > 0) {
if (origin < 0)
origin = 0;
if ((n = count) > len)
n = len;
int fence = bound < 0 || bound > n ? n : bound;
Iterator it = list.iterator();
for (int i = origin; i < fence; ++i) {
if (!it.hasNext())
return false;
Object y = it.next();
Object x = items[i];
if (x != y && (x == null || !x.equals(y)))
return false;
}
if (it.hasNext())
return false;
}
else if (!list.isEmpty())
return false;
return true;
}
final int internalHashCode(int origin, int bound) {
int hash = 1;
Object[] items;
int n, len;
if ((items = array) != null && (len = items.length) > 0) {
if (origin < 0)
origin = 0;
if ((n = count) > len)
n = len;
int fence = bound < 0 || bound > n ? n : bound;
for (int i = origin; i < fence; ++i) {
Object e = items[i];
hash = 31*hash + (e == null ? 0 : e.hashCode());
}
}
return hash;
}
final String internalToString(int origin, int bound) {
Object[] items;
int n, len;
if ((items = array) != null && (len = items.length) > 0) {
if ((n = count) > len)
n = len;
int fence = bound < 0 || bound > n ? n : bound;
int i = (origin < 0) ? 0 : origin;
if (i != fence) {
StringBuilder sb = new StringBuilder();
sb.append('[');
for (;;) {
Object e = items[i];
sb.append((e == this) ? "(this Collection)" : e.toString());
if (++i < fence)
sb.append(',').append(' ');
else
return sb.append(']').toString();
}
}
}
return "[]";
}
final Object[] internalToArray(int origin, int bound) {
Object[] items;
int n, len;
if ((items = array) != null && (len = items.length) > 0) {
if (origin < 0)
origin = 0;
if ((n = count) > len)
n = len;
int fence = bound < 0 || bound > n ? n : bound;
int i = (origin < 0) ? 0 : origin;
if (i != fence)
return Arrays.copyOfRange(items, i, fence, Object[].class);
}
return new Object[0];
}
@SuppressWarnings("unchecked")
final T[] internalToArray(T[] a, int origin, int bound) {
int alen = a.length;
Object[] items;
int n, len;
if ((items = array) != null && (len = items.length) > 0) {
if (origin < 0)
origin = 0;
if ((n = count) > len)
n = len;
int fence = bound < 0 || bound > n ? n : bound;
int i = (origin < 0) ? 0 : origin;
int rlen = fence - origin;
if (rlen > 0) {
if (alen >= rlen) {
System.arraycopy(items, 0, a, origin, rlen);
if (alen > rlen)
a[rlen] = null;
return a;
}
return (T[]) Arrays.copyOfRange(items, i, fence, a.getClass());
}
}
if (alen > 0)
a[0] = null;
return a;
}
// public List methods
public boolean add(E e) {
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
rawAdd(e);
} finally {
lock.unlockWrite(stamp);
}
return true;
}
public void add(int index, E element) {
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
rawAddAt(index, element);
} finally {
lock.unlockWrite(stamp);
}
}
public boolean addAll(Collection c) {
Object[] elements = c.toArray();
int len = elements.length;
if (len == 0)
return false;
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
Object[] items = array;
int n = count;
int newCount = n + len;
if (items == null || newCount >= items.length)
items = grow(newCount);
System.arraycopy(elements, 0, items, n, len);
count = newCount;
} finally {
lock.unlockWrite(stamp);
}
return true;
}
public boolean addAll(int index, Collection c) {
Object[] elements = c.toArray();
boolean ret;
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
ret = rawAddAllAt(index, elements);
} finally {
lock.unlockWrite(stamp);
}
return ret;
}
public void clear() {
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
int n = count;
Object[] items = array;
if (items != null) {
for (int i = 0; i < n; i++)
items[i] = null;
}
count = 0;
} finally {
lock.unlockWrite(stamp);
}
}
public boolean contains(Object o) {
return indexOf(o, 0) >= 0;
}
public boolean containsAll(Collection c) {
boolean ret;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
ret = internalContainsAll(c, 0, -1);
} finally {
lock.unlockRead(stamp);
}
return ret;
}
public boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof List))
return false;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
return internalEquals((List)o, 0, -1);
} finally {
lock.unlockRead(stamp);
}
}
public E get(int index) {
final StampedLock lock = this.lock;
long stamp = lock.tryOptimisticRead();
Object[] items;
if (index >= 0 && (items = array) != null &&
index < count && index < items.length) {
@SuppressWarnings("unchecked") E e = (E)items[index];
if (lock.validate(stamp))
return e;
}
return lockedGet(index);
}
@SuppressWarnings("unchecked") private E lockedGet(int index) {
boolean oobe = false;
E e = null;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
Object[] items;
if ((items = array) != null && index < items.length &&
index < count && index >= 0)
e = (E)items[index];
else
oobe = true;
} finally {
lock.unlockRead(stamp);
}
if (oobe)
throw new ArrayIndexOutOfBoundsException(index);
return e;
}
public int hashCode() {
int h;
final StampedLock lock = this.lock;
long s = lock.readLock();
try {
h = internalHashCode(0, -1);
} finally {
lock.unlockRead(s);
}
return h;
}
public int indexOf(Object o) {
int idx;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
idx = findFirstIndex(array, o, 0, count);
} finally {
lock.unlockRead(stamp);
}
return idx;
}
public boolean isEmpty() {
final StampedLock lock = this.lock;
long stamp = lock.tryOptimisticRead();
return count == 0; // no need for validation
}
public Iterator iterator() {
return new Itr(this, 0);
}
public int lastIndexOf(Object o) {
int idx;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
idx = findLastIndex(array, o, count - 1, 0);
} finally {
lock.unlockRead(stamp);
}
return idx;
}
public ListIterator listIterator() {
return new Itr(this, 0);
}
public ListIterator listIterator(int index) {
return new Itr(this, index);
}
@SuppressWarnings("unchecked") public E remove(int index) {
E oldValue = null;
boolean oobe = false;
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
if (index < 0 || index >= count)
oobe = true;
else {
oldValue = (E) array[index];
rawRemoveAt(index);
}
} finally {
lock.unlockWrite(stamp);
}
if (oobe)
throw new ArrayIndexOutOfBoundsException(index);
return oldValue;
}
public boolean remove(Object o) {
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
return rawRemoveAt(findFirstIndex(array, o, 0, count));
} finally {
lock.unlockWrite(stamp);
}
}
public boolean removeAll(Collection c) {
return lockedRemoveAll(c, 0, -1);
}
public boolean retainAll(Collection c) {
return lockedRetainAll(c, 0, -1);
}
@SuppressWarnings("unchecked") public E set(int index, E element) {
E oldValue = null;
boolean oobe = false;
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
Object[] items = array;
if (items == null || index < 0 || index >= count)
oobe = true;
else {
oldValue = (E) items[index];
items[index] = element;
}
} finally {
lock.unlockWrite(stamp);
}
if (oobe)
throw new ArrayIndexOutOfBoundsException(index);
return oldValue;
}
public int size() {
final StampedLock lock = this.lock;
long stamp = lock.tryOptimisticRead();
return count; // no need for validation
}
private int lockedSize() {
int n;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
n = count;
} finally {
lock.unlockRead(stamp);
}
return n;
}
public List subList(int fromIndex, int toIndex) {
int ssize = toIndex - fromIndex;
if (ssize >= 0 && fromIndex >= 0) {
ReadMostlyVectorSublist ret = null;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
if (toIndex <= count)
ret = new ReadMostlyVectorSublist(this, fromIndex, ssize);
} finally {
lock.unlockRead(stamp);
}
if (ret != null)
return ret;
}
throw new ArrayIndexOutOfBoundsException(fromIndex < 0 ? fromIndex : toIndex);
}
public Object[] toArray() {
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
return internalToArray(0, -1);
} finally {
lock.unlockRead(stamp);
}
}
public T[] toArray(T[] a) {
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
return internalToArray(a, 0, -1);
} finally {
lock.unlockRead(stamp);
}
}
public String toString() {
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
return internalToString(0, -1);
} finally {
lock.unlockRead(stamp);
}
}
// ReadMostlyVector-only methods
/**
* Appends the element, if not present.
*
* @param e element to be added to this list, if absent
* @return {@code true} if the element was added
*/
public boolean addIfAbsent(E e) {
boolean ret;
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
if (findFirstIndex(array, e, 0, count) < 0) {
rawAdd(e);
ret = true;
}
else
ret = false;
} finally {
lock.unlockWrite(stamp);
}
return ret;
}
/**
* Appends all of the elements in the specified collection that
* are not already contained in this list, to the end of
* this list, in the order that they are returned by the
* specified collection's iterator.
*
* @param c collection containing elements to be added to this list
* @return the number of elements added
* @throws NullPointerException if the specified collection is null
* @see #addIfAbsent(Object)
*/
public int addAllAbsent(Collection c) {
int added = 0;
Object[] cs = c.toArray();
int clen = cs.length;
if (clen != 0) {
long stamp = lock.writeLock();
try {
for (int i = 0; i < clen; ++i) {
@SuppressWarnings("unchecked")
E e = (E) cs[i];
if (findFirstIndex(array, e, 0, count) < 0) {
rawAdd(e);
++added;
}
}
} finally {
lock.unlockWrite(stamp);
}
}
return added;
}
/**
* Returns an iterator operating over a snapshot copy of the
* elements of this collection created upon construction of the
* iterator. The iterator does NOT support the
* {@code remove} method.
*
* @return an iterator over the elements in this list in proper sequence
*/
public Iterator snapshotIterator() {
return new SnapshotIterator(this);
}
static final class SnapshotIterator implements Iterator {
private final Object[] items;
private int cursor;
SnapshotIterator(ReadMostlyVector v) { items = v.toArray(); }
public boolean hasNext() { return cursor < items.length; }
@SuppressWarnings("unchecked") public E next() {
if (cursor < items.length)
return (E) items[cursor++];
throw new NoSuchElementException();
}
public void remove() { throw new UnsupportedOperationException() ; }
}
/** Interface describing a void action of one argument */
public interface Action { void apply(A a); }
public void forEachReadOnly(Action action) {
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
Object[] items;
int len, n;
if ((items = array) != null && (len = items.length) > 0 &&
(n = count) <= len) {
for (int i = 0; i < n; ++i) {
@SuppressWarnings("unchecked") E e = (E)items[i];
action.apply(e);
}
}
} finally {
lock.unlockRead(stamp);
}
}
// Vector-only methods
/** See {@link Vector#firstElement} */
public E firstElement() {
final StampedLock lock = this.lock;
long stamp = lock.tryOptimisticRead();
Object[] items;
if ((items = array) != null && count > 0 && items.length > 0) {
@SuppressWarnings("unchecked") E e = (E)items[0];
if (lock.validate(stamp))
return e;
}
return lockedFirstElement();
}
@SuppressWarnings("unchecked") private E lockedFirstElement() {
Object e = null;
boolean oobe = false;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
Object[] items = array;
if (items != null && count > 0 && items.length > 0)
e = items[0];
else
oobe = true;
} finally {
lock.unlockRead(stamp);
}
if (oobe)
throw new NoSuchElementException();
return (E) e;
}
/** See {@link Vector#lastElement} */
public E lastElement() {
final StampedLock lock = this.lock;
long stamp = lock.tryOptimisticRead();
Object[] items;
int i;
if ((items = array) != null && (i = count - 1) >= 0 &&
i < items.length) {
@SuppressWarnings("unchecked") E e = (E)items[i];
if (lock.validate(stamp))
return e;
}
return lockedLastElement();
}
@SuppressWarnings("unchecked") private E lockedLastElement() {
Object e = null;
boolean oobe = false;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
Object[] items = array;
int i = count - 1;
if (items != null && i >= 0 && i < items.length)
e = items[i];
else
oobe = true;
} finally {
lock.unlockRead(stamp);
}
if (oobe)
throw new NoSuchElementException();
return (E) e;
}
/** See {@link Vector#indexOf(Object, int)} */
public int indexOf(Object o, int index) {
if (index < 0)
throw new ArrayIndexOutOfBoundsException(index);
int idx;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
idx = findFirstIndex(array, o, index, count);
} finally {
lock.unlockRead(stamp);
}
return idx;
}
/** See {@link Vector#lastIndexOf(Object, int)} */
public int lastIndexOf(Object o, int index) {
boolean oobe = false;
int idx = -1;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
if (index < count)
idx = findLastIndex(array, o, index, 0);
else
oobe = true;
} finally {
lock.unlockRead(stamp);
}
if (oobe)
throw new ArrayIndexOutOfBoundsException(index);
return idx;
}
/** See {@link Vector#setSize} */
public void setSize(int newSize) {
if (newSize < 0)
throw new ArrayIndexOutOfBoundsException(newSize);
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
Object[] items;
int n = count;
if (newSize > n)
grow(newSize);
else if ((items = array) != null) {
for (int i = newSize ; i < n ; i++)
items[i] = null;
}
count = newSize;
} finally {
lock.unlockWrite(stamp);
}
}
/** See {@link Vector#copyInto} */
public void copyInto(Object[] anArray) {
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
Object[] items;
if ((items = array) != null)
System.arraycopy(items, 0, anArray, 0, count);
} finally {
lock.unlockWrite(stamp);
}
}
/** See {@link Vector#trimToSize} */
public void trimToSize() {
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
Object[] items = array;
int n = count;
if (items != null && n < items.length)
array = Arrays.copyOf(items, n);
} finally {
lock.unlockWrite(stamp);
}
}
/** See {@link Vector#ensureCapacity} */
public void ensureCapacity(int minCapacity) {
if (minCapacity > 0) {
final StampedLock lock = this.lock;
long stamp = lock.writeLock();
try {
Object[] items = array;
int cap = (items == null) ? 0 : items.length;
if (minCapacity - cap > 0)
grow(minCapacity);
} finally {
lock.unlockWrite(stamp);
}
}
}
/** See {@link Vector#elements} */
public Enumeration elements() {
return new Itr(this, 0);
}
/** See {@link Vector#capacity} */
public int capacity() {
return array.length;
}
/** See {@link Vector#elementAt} */
public E elementAt(int index) {
return get(index);
}
/** See {@link Vector#setElementAt} */
public void setElementAt(E obj, int index) {
set(index, obj);
}
/** See {@link Vector#removeElementAt} */
public void removeElementAt(int index) {
remove(index);
}
/** See {@link Vector#insertElementAt} */
public void insertElementAt(E obj, int index) {
add(index, obj);
}
/** See {@link Vector#addElement} */
public void addElement(E obj) {
add(obj);
}
/** See {@link Vector#removeElement} */
public boolean removeElement(Object obj) {
return remove(obj);
}
/** See {@link Vector#removeAllElements} */
public void removeAllElements() {
clear();
}
// other methods
public ReadMostlyVector clone() {
Object[] a = null;
int n;
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
Object[] items = array;
if (items == null)
n = 0;
else {
int len = items.length;
if ((n = count) > len)
n = len;
a = Arrays.copyOf(items, n);
}
} finally {
lock.unlockRead(stamp);
}
return new ReadMostlyVector(a, n, capacityIncrement);
}
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
final StampedLock lock = this.lock;
long stamp = lock.readLock();
try {
s.defaultWriteObject();
} finally {
lock.unlockRead(stamp);
}
}
static final class Itr implements ListIterator, Enumeration {
final StampedLock lock;
final ReadMostlyVector list;
Object[] items;
long seq;
int cursor;
int fence;
int lastRet;
Itr(ReadMostlyVector list, int index) {
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
this.list = list;
this.lock = lock;
this.items = list.array;
this.fence = list.count;
this.cursor = index;
this.lastRet = -1;
} finally {
this.seq = lock.tryConvertToOptimisticRead(stamp);
}
if (index < 0 || index > fence)
throw new ArrayIndexOutOfBoundsException(index);
}
public boolean hasPrevious() {
return cursor > 0;
}
public int nextIndex() {
return cursor;
}
public int previousIndex() {
return cursor - 1;
}
public boolean hasNext() {
return cursor < fence;
}
public E next() {
int i = cursor;
Object[] es = items;
if (es == null || i < 0 || i >= fence || i >= es.length)
throw new NoSuchElementException();
@SuppressWarnings("unchecked") E e = (E)es[i];
lastRet = i;
cursor = i + 1;
if (!lock.validate(seq))
throw new ConcurrentModificationException();
return e;
}
public E previous() {
int i = cursor - 1;
Object[] es = items;
if (es == null || i < 0 || i >= fence || i >= es.length)
throw new NoSuchElementException();
@SuppressWarnings("unchecked") E e = (E)es[i];
lastRet = i;
cursor = i;
if (!lock.validate(seq))
throw new ConcurrentModificationException();
return e;
}
public void remove() {
int i = lastRet;
if (i < 0)
throw new IllegalStateException();
if ((seq = lock.tryConvertToWriteLock(seq)) == 0)
throw new ConcurrentModificationException();
try {
list.rawRemoveAt(i);
fence = list.count;
cursor = i;
lastRet = -1;
} finally {
seq = lock.tryConvertToOptimisticRead(seq);
}
}
public void set(E e) {
int i = lastRet;
Object[] es = items;
if (es == null || i < 0 | i >= fence)
throw new IllegalStateException();
if ((seq = lock.tryConvertToWriteLock(seq)) == 0)
throw new ConcurrentModificationException();
try {
es[i] = e;
} finally {
seq = lock.tryConvertToOptimisticRead(seq);
}
}
public void add(E e) {
int i = cursor;
if (i < 0)
throw new IllegalStateException();
if ((seq = lock.tryConvertToWriteLock(seq)) == 0)
throw new ConcurrentModificationException();
try {
list.rawAddAt(i, e);
items = list.array;
fence = list.count;
cursor = i + 1;
lastRet = -1;
} finally {
seq = lock.tryConvertToOptimisticRead(seq);
}
}
public boolean hasMoreElements() { return hasNext(); }
public E nextElement() { return next(); }
}
static final class ReadMostlyVectorSublist
implements List, RandomAccess, java.io.Serializable {
private static final long serialVersionUID = 3041673470172026059L;
final ReadMostlyVector list;
final int offset;
volatile int size;
ReadMostlyVectorSublist(ReadMostlyVector list,
int offset, int size) {
this.list = list;
this.offset = offset;
this.size = size;
}
private void rangeCheck(int index) {
if (index < 0 || index >= size)
throw new ArrayIndexOutOfBoundsException(index);
}
public boolean add(E element) {
final StampedLock lock = list.lock;
long stamp = lock.writeLock();
try {
int c = size;
list.rawAddAt(c + offset, element);
size = c + 1;
} finally {
lock.unlockWrite(stamp);
}
return true;
}
public void add(int index, E element) {
final StampedLock lock = list.lock;
long stamp = lock.writeLock();
try {
if (index < 0 || index > size)
throw new ArrayIndexOutOfBoundsException(index);
list.rawAddAt(index + offset, element);
++size;
} finally {
lock.unlockWrite(stamp);
}
}
public boolean addAll(Collection c) {
Object[] elements = c.toArray();
final StampedLock lock = list.lock;
long stamp = lock.writeLock();
try {
int s = size;
int pc = list.count;
list.rawAddAllAt(offset + s, elements);
int added = list.count - pc;
size = s + added;
return added != 0;
} finally {
lock.unlockWrite(stamp);
}
}
public boolean addAll(int index, Collection c) {
Object[] elements = c.toArray();
final StampedLock lock = list.lock;
long stamp = lock.writeLock();
try {
int s = size;
if (index < 0 || index > s)
throw new ArrayIndexOutOfBoundsException(index);
int pc = list.count;
list.rawAddAllAt(index + offset, elements);
int added = list.count - pc;
size = s + added;
return added != 0;
} finally {
lock.unlockWrite(stamp);
}
}
public void clear() {
final StampedLock lock = list.lock;
long stamp = lock.writeLock();
try {
list.internalClear(offset, offset + size);
size = 0;
} finally {
lock.unlockWrite(stamp);
}
}
public boolean contains(Object o) {
return indexOf(o) >= 0;
}
public boolean containsAll(Collection c) {
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
return list.internalContainsAll(c, offset, offset + size);
} finally {
lock.unlockRead(stamp);
}
}
public boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof List))
return false;
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
return list.internalEquals((List)(o), offset, offset + size);
} finally {
lock.unlockRead(stamp);
}
}
public E get(int index) {
if (index < 0 || index >= size)
throw new ArrayIndexOutOfBoundsException(index);
return list.get(index + offset);
}
public int hashCode() {
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
return list.internalHashCode(offset, offset + size);
} finally {
lock.unlockRead(stamp);
}
}
public int indexOf(Object o) {
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
int idx = findFirstIndex(list.array, o, offset, offset + size);
return idx < 0 ? -1 : idx - offset;
} finally {
lock.unlockRead(stamp);
}
}
public boolean isEmpty() {
return size() == 0;
}
public Iterator iterator() {
return new SubItr(this, offset);
}
public int lastIndexOf(Object o) {
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
int idx = findLastIndex(list.array, o, offset + size - 1, offset);
return idx < 0 ? -1 : idx - offset;
} finally {
lock.unlockRead(stamp);
}
}
public ListIterator listIterator() {
return new SubItr(this, offset);
}
public ListIterator listIterator(int index) {
return new SubItr(this, index + offset);
}
public E remove(int index) {
final StampedLock lock = list.lock;
long stamp = lock.writeLock();
try {
Object[] items = list.array;
int i = index + offset;
if (items == null || index < 0 || index >= size || i >= items.length)
throw new ArrayIndexOutOfBoundsException(index);
@SuppressWarnings("unchecked") E result = (E)items[i];
list.rawRemoveAt(i);
size--;
return result;
} finally {
lock.unlockWrite(stamp);
}
}
public boolean remove(Object o) {
final StampedLock lock = list.lock;
long stamp = lock.writeLock();
try {
if (list.rawRemoveAt(findFirstIndex(list.array, o, offset,
offset + size))) {
--size;
return true;
}
else
return false;
} finally {
lock.unlockWrite(stamp);
}
}
public boolean removeAll(Collection c) {
return list.lockedRemoveAll(c, offset, offset + size);
}
public boolean retainAll(Collection c) {
return list.lockedRetainAll(c, offset, offset + size);
}
public E set(int index, E element) {
if (index < 0 || index >= size)
throw new ArrayIndexOutOfBoundsException(index);
return list.set(index+offset, element);
}
public int size() {
return size;
}
public List subList(int fromIndex, int toIndex) {
int c = size;
int ssize = toIndex - fromIndex;
if (fromIndex < 0)
throw new ArrayIndexOutOfBoundsException(fromIndex);
if (toIndex > c || ssize < 0)
throw new ArrayIndexOutOfBoundsException(toIndex);
return new ReadMostlyVectorSublist(list, offset+fromIndex, ssize);
}
public Object[] toArray() {
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
return list.internalToArray(offset, offset + size);
} finally {
lock.unlockRead(stamp);
}
}
public T[] toArray(T[] a) {
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
return list.internalToArray(a, offset, offset + size);
} finally {
lock.unlockRead(stamp);
}
}
public String toString() {
final StampedLock lock = list.lock;
long stamp = lock.readLock();
try {
return list.internalToString(offset, offset + size);
} finally {
lock.unlockRead(stamp);
}
}
}
static final class SubItr implements ListIterator {
final ReadMostlyVectorSublist sublist;
final ReadMostlyVector list;
final StampedLock lock;
Object[] items;
long seq;
int cursor;
int origin;
int fence;
int lastRet;
SubItr(ReadMostlyVectorSublist sublist, int index) {
final StampedLock lock = sublist.list.lock;
long stamp = lock.readLock();
try {
this.sublist = sublist;
this.list = sublist.list;
this.lock = lock;
this.cursor = index;
this.origin = sublist.offset;
this.fence = origin + sublist.size;
this.lastRet = -1;
} finally {
this.seq = lock.tryConvertToOptimisticRead(stamp);
}
if (index < 0 || cursor > fence)
throw new ArrayIndexOutOfBoundsException(index);
}
public int nextIndex() {
return cursor - origin;
}
public int previousIndex() {
return cursor - origin - 1;
}
public boolean hasNext() {
return cursor < fence;
}
public boolean hasPrevious() {
return cursor > origin;
}
public E next() {
int i = cursor;
Object[] es = items;
if (es == null || i < origin || i >= fence || i >= es.length)
throw new NoSuchElementException();
@SuppressWarnings("unchecked") E e = (E)es[i];
lastRet = i;
cursor = i + 1;
if (!lock.validate(seq))
throw new ConcurrentModificationException();
return e;
}
public E previous() {
int i = cursor - 1;
Object[] es = items;
if (es == null || i < 0 || i >= fence || i >= es.length)
throw new NoSuchElementException();
@SuppressWarnings("unchecked") E e = (E)es[i];
lastRet = i;
cursor = i;
if (!lock.validate(seq))
throw new ConcurrentModificationException();
return e;
}
public void remove() {
int i = lastRet;
if (i < 0)
throw new IllegalStateException();
if ((seq = lock.tryConvertToWriteLock(seq)) == 0)
throw new ConcurrentModificationException();
try {
list.rawRemoveAt(i);
fence = origin + sublist.size;
cursor = i;
lastRet = -1;
} finally {
seq = lock.tryConvertToOptimisticRead(seq);
}
}
public void set(E e) {
int i = lastRet;
if (i < origin || i >= fence)
throw new IllegalStateException();
if ((seq = lock.tryConvertToWriteLock(seq)) == 0)
throw new ConcurrentModificationException();
try {
list.set(i, e);
} finally {
seq = lock.tryConvertToOptimisticRead(seq);
}
}
public void add(E e) {
int i = cursor;
if (i < origin || i >= fence)
throw new IllegalStateException();
if ((seq = lock.tryConvertToWriteLock(seq)) == 0)
throw new ConcurrentModificationException();
try {
list.rawAddAt(i, e);
items = list.array;
fence = origin + sublist.size;
cursor = i + 1;
lastRet = -1;
} finally {
seq = lock.tryConvertToOptimisticRead(seq);
}
}
}
}