Fix FastArrayList iterator to work in thread-safe environments
git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@131802 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Stephen Colebourne
parent
72ed906100
commit
ac06284e5a
|
|
@ -57,9 +57,10 @@ import java.util.ListIterator;
|
|||
* Double-Checked Locking Idiom Is Broken Declaration</a>.</p>
|
||||
*
|
||||
* @since Commons Collections 1.0
|
||||
* @version $Revision: 1.15 $ $Date: 2004/02/18 01:15:42 $
|
||||
* @version $Revision: 1.16 $ $Date: 2004/06/23 21:41:49 $
|
||||
*
|
||||
* @author Craig R. McClanahan
|
||||
* @author Stephen Colebourne
|
||||
*/
|
||||
public class FastArrayList extends ArrayList {
|
||||
|
||||
|
|
@ -486,12 +487,20 @@ public class FastArrayList extends ArrayList {
|
|||
|
||||
/**
|
||||
* Return an iterator over the elements in this list in proper sequence.
|
||||
* <br><br>
|
||||
* <strong>IMPLEMENTATION NOTE</strong> - If the list is operating in fast
|
||||
* mode, an Iterator is returned, and a structural modification to the
|
||||
* list is made, then the Iterator will continue over the previous contents
|
||||
* of the list (at the time that the Iterator was created), rather than
|
||||
* failing due to concurrent modifications.
|
||||
* <p>
|
||||
* <b>Thread safety</b><br />
|
||||
* The iterator returned is thread-safe ONLY in FAST mode.
|
||||
* In slow mode there is no way to synchronize, or make the iterator thread-safe.
|
||||
* <p>
|
||||
* In fast mode iteration and modification may occur in parallel on different threads,
|
||||
* however there is a restriction. Modification must be EITHER via the Iterator
|
||||
* interface methods OR the List interface. If a mixture of modification
|
||||
* methods is used a ConcurrentModificationException is thrown from the iterator
|
||||
* modification method. If the List modification methods are used the changes are
|
||||
* NOT visible in the iterator (it shows the list contents at the time the iterator
|
||||
* was created).
|
||||
*
|
||||
* @return the iterator
|
||||
*/
|
||||
public Iterator iterator() {
|
||||
if (fast) {
|
||||
|
|
@ -524,7 +533,20 @@ public class FastArrayList extends ArrayList {
|
|||
|
||||
/**
|
||||
* Return an iterator of the elements of this list, in proper sequence.
|
||||
* See the implementation note on <code>iterator()</code>.
|
||||
* <p>
|
||||
* <b>Thread safety</b><br />
|
||||
* The iterator returned is thread-safe ONLY in FAST mode.
|
||||
* In slow mode there is no way to synchronize, or make the iterator thread-safe.
|
||||
* <p>
|
||||
* In fast mode iteration and modification may occur in parallel on different threads,
|
||||
* however there is a restriction. Modification must be EITHER via the Iterator
|
||||
* interface methods OR the List interface. If a mixture of modification
|
||||
* methods is used a ConcurrentModificationException is thrown from the iterator
|
||||
* modification method. If the List modification methods are used the changes are
|
||||
* NOT visible in the iterator (it shows the list contents at the time the iterator
|
||||
* was created).
|
||||
*
|
||||
* @return the list iterator
|
||||
*/
|
||||
public ListIterator listIterator() {
|
||||
if (fast) {
|
||||
|
|
@ -538,10 +560,21 @@ public class FastArrayList extends ArrayList {
|
|||
/**
|
||||
* Return an iterator of the elements of this list, in proper sequence,
|
||||
* starting at the specified position.
|
||||
* See the implementation note on <code>iterator()</code>.
|
||||
* <p>
|
||||
* <b>Thread safety</b><br />
|
||||
* The iterator returned is thread-safe ONLY in FAST mode.
|
||||
* In slow mode there is no way to synchronize, or make the iterator thread-safe.
|
||||
* <p>
|
||||
* In fast mode iteration and modification may occur in parallel on different threads,
|
||||
* however there is a restriction. Modification must be EITHER via the Iterator
|
||||
* interface methods OR the List interface. If a mixture of modification
|
||||
* methods is used a ConcurrentModificationException is thrown from the iterator
|
||||
* modification method. If the List modification methods are used the changes are
|
||||
* NOT visible in the iterator (it shows the list contents at the time the iterator
|
||||
* was created).
|
||||
*
|
||||
* @param index The starting position of the iterator to return
|
||||
*
|
||||
* @return the list iterator
|
||||
* @exception IndexOutOfBoundsException if the index is out of range
|
||||
*/
|
||||
public ListIterator listIterator(int index) {
|
||||
|
|
@ -1205,8 +1238,9 @@ public class FastArrayList extends ArrayList {
|
|||
int i = nextIndex();
|
||||
get().add(i, o);
|
||||
last++;
|
||||
expected = list;
|
||||
iter = get().listIterator(i + 1);
|
||||
lastReturnedIndex = 1;
|
||||
lastReturnedIndex = -1;
|
||||
}
|
||||
|
||||
}
|
||||
|
|
@ -1239,34 +1273,28 @@ public class FastArrayList extends ArrayList {
|
|||
}
|
||||
|
||||
public boolean hasNext() {
|
||||
checkMod();
|
||||
return iter.hasNext();
|
||||
}
|
||||
|
||||
public Object next() {
|
||||
checkMod();
|
||||
lastReturnedIndex = iter.nextIndex();
|
||||
return iter.next();
|
||||
}
|
||||
|
||||
public boolean hasPrevious() {
|
||||
checkMod();
|
||||
return iter.hasPrevious();
|
||||
}
|
||||
|
||||
public Object previous() {
|
||||
checkMod();
|
||||
lastReturnedIndex = iter.previousIndex();
|
||||
return iter.previous();
|
||||
}
|
||||
|
||||
public int previousIndex() {
|
||||
checkMod();
|
||||
return iter.previousIndex();
|
||||
}
|
||||
|
||||
public int nextIndex() {
|
||||
checkMod();
|
||||
return iter.nextIndex();
|
||||
}
|
||||
|
||||
|
|
@ -1295,6 +1323,7 @@ public class FastArrayList extends ArrayList {
|
|||
checkMod();
|
||||
int i = nextIndex();
|
||||
get().add(i, o);
|
||||
expected = list;
|
||||
iter = get().listIterator(i + 1);
|
||||
lastReturnedIndex = -1;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -16,14 +16,17 @@
|
|||
package org.apache.commons.collections;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.ConcurrentModificationException;
|
||||
import java.util.Iterator;
|
||||
import java.util.List;
|
||||
import java.util.ListIterator;
|
||||
|
||||
import junit.framework.Test;
|
||||
|
||||
/**
|
||||
* Test FastArrayList implementation in <strong>fast</strong> mode.
|
||||
*
|
||||
* @version $Revision: 1.9 $ $Date: 2004/02/18 01:20:35 $
|
||||
* @version $Revision: 1.10 $ $Date: 2004/06/23 21:41:49 $
|
||||
*
|
||||
* @author Jason van Zyl
|
||||
*/
|
||||
|
|
@ -52,12 +55,51 @@ public class TestFastArrayList1 extends TestFastArrayList {
|
|||
return (fal);
|
||||
}
|
||||
|
||||
public String[] ignoredTests() {
|
||||
// subList impl result in...
|
||||
return new String[] {
|
||||
"TestFastArrayList1.bulkTestSubList.bulkTestListIterator.testAddThenSet",
|
||||
"TestFastArrayList1.bulkTestSubList.bulkTestListIterator.testAddThenRemove",
|
||||
};
|
||||
public void testIterateModify1() {
|
||||
List list = makeEmptyList();
|
||||
list.add("A");
|
||||
list.add("B");
|
||||
list.add("C");
|
||||
assertEquals(3, list.size());
|
||||
|
||||
Iterator it = list.iterator();
|
||||
assertEquals("A", it.next());
|
||||
assertEquals(3, list.size());
|
||||
list.add(1, "Z");
|
||||
assertEquals(4, list.size());
|
||||
assertEquals("B", it.next());
|
||||
assertEquals("C", it.next());
|
||||
assertEquals(false, it.hasNext());
|
||||
}
|
||||
|
||||
public void testIterateModify2() {
|
||||
List list = makeEmptyList();
|
||||
list.add("A");
|
||||
list.add("B");
|
||||
list.add("C");
|
||||
assertEquals(3, list.size());
|
||||
|
||||
ListIterator it = list.listIterator();
|
||||
assertEquals("A", it.next());
|
||||
it.add("M"); // change via Iterator interface
|
||||
assertEquals(4, list.size());
|
||||
list.add(2, "Z"); // change via List interface
|
||||
assertEquals(5, list.size());
|
||||
assertEquals("B", it.next());
|
||||
try {
|
||||
it.set("N"); // fails as previously changed via List interface
|
||||
fail();
|
||||
} catch (ConcurrentModificationException ex) {}
|
||||
try {
|
||||
it.remove();
|
||||
fail();
|
||||
} catch (ConcurrentModificationException ex) {}
|
||||
try {
|
||||
it.add("N");
|
||||
fail();
|
||||
} catch (ConcurrentModificationException ex) {}
|
||||
assertEquals("C", it.next());
|
||||
assertEquals(false, it.hasNext());
|
||||
}
|
||||
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue