infernap12/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2026-06-06 02:33:12 +00:00
Code Issues Packages Projects Releases Wiki Activity

7062169: (coll) micro-optimize ArrayList.remove(Object)

Browse Source 
Reviewed-by: martin, psandoz, igerasim
This commit is contained in:
Doug Lea 2017-07-22 09:03:50 -07:00
parent ddd48329ea
commit a2667824fb
1 changed files with 46 additions and 48 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

94
jdk/src/java.base/share/classes/java/util/ArrayList.java
View File

@ -514,15 +514,10 @@ public class ArrayList<E> extends AbstractList<E>
*/
public E remove(int index) {
Objects.checkIndex(index, size);
final Object[] es = elementData;
modCount++;
E oldValue = elementData(index);
int numMoved = size - index - 1;
if (numMoved > 0)
System.arraycopy(elementData, index+1, elementData, index,
numMoved);
elementData[--size] = null; // clear to let GC do its work
@SuppressWarnings("unchecked") E oldValue = (E) es[index];
fastRemove(es, index);
return oldValue;
}
@ -541,33 +536,35 @@ public class ArrayList<E> extends AbstractList<E>
* @return {@code true} if this list contained the specified element
*/
public boolean remove(Object o) {
if (o == null) {
for (int index = 0; index < size; index++)
if (elementData[index] == null) {
fastRemove(index);
return true;
}
} else {
for (int index = 0; index < size; index++)
if (o.equals(elementData[index])) {
fastRemove(index);
return true;
}
final Object[] es = elementData;
final int size = this.size;
int i = 0;
found: {
if (o == null) {
for (; i < size; i++)
if (es[i] == null)
break found;
} else {
for (; i < size; i++)
if (o.equals(es[i]))
break found;
}
return false;
}
return false;
fastRemove(es, i);
return true;
}
/**
* Private remove method that skips bounds checking and does not
* return the value removed.
*/
private void fastRemove(int index) {
private void fastRemove(Object[] es, int i) {
modCount++;
int numMoved = size - index - 1;
if (numMoved > 0)
System.arraycopy(elementData, index+1, elementData, index,
numMoved);
elementData[--size] = null; // clear to let GC do its work
final int newSize;
if ((newSize = size - 1) > i)
System.arraycopy(es, i + 1, es, i, newSize - i);
es[size = newSize] = null;
}
/**
@ -743,29 +740,30 @@ public class ArrayList<E> extends AbstractList<E>
final int from, final int end) {
Objects.requireNonNull(c);
final Object[] es = elementData;
final boolean modified;
int r;
// Optimize for initial run of survivors
for (r = from; r < end && c.contains(es[r]) == complement; r++)
;
if (modified = (r < end)) {
int w = r++;
try {
for (Object e; r < end; r++)
if (c.contains(e = es[r]) == complement)
es[w++] = e;
} catch (Throwable ex) {
// Preserve behavioral compatibility with AbstractCollection,
// even if c.contains() throws.
System.arraycopy(es, r, es, w, end - r);
w += end - r;
throw ex;
} finally {
modCount += end - w;
shiftTailOverGap(es, w, end);
}
for (r = from;; r++) {
if (r == end)
return false;
if (c.contains(es[r]) != complement)
break;
}
return modified;
int w = r++;
try {
for (Object e; r < end; r++)
if (c.contains(e = es[r]) == complement)
es[w++] = e;
} catch (Throwable ex) {
// Preserve behavioral compatibility with AbstractCollection,
// even if c.contains() throws.
System.arraycopy(es, r, es, w, end - r);
w += end - r;
throw ex;
} finally {
modCount += end - w;
shiftTailOverGap(es, w, end);
}
return true;
}
/**
@ -784,7 +782,7 @@ public class ArrayList<E> extends AbstractList<E>
int expectedModCount = modCount;
s.defaultWriteObject();
// Write out size as capacity for behavioural compatibility with clone()
// Write out size as capacity for behavioral compatibility with clone()
s.writeInt(size);
// Write out all elements in the proper order.