Copilot commented on code in PR #719:
URL:
https://github.com/apache/commons-collections/pull/719#discussion_r3677680438
##########
src/main/java/org/apache/commons/collections4/properties/OrderedProperties.java:
##########
@@ -134,6 +211,37 @@ public synchronized Object merge(final Object key, final
Object value,
return merge;
}
+ /**
+ * Creates an iterator over the keys in insertion order whose {@link
Iterator#remove()} also removes the mapping.
+ *
+ * @return A new iterator.
+ */
+ private Iterator<Object> orderedKeysIterator() {
+ final Iterator<Object> iterator = orderedKeys.iterator();
+ return new Iterator<Object>() {
+
+ private Object last;
+
+ @Override
+ public boolean hasNext() {
+ return iterator.hasNext();
+ }
+
+ @Override
+ public Object next() {
+ last = iterator.next();
+ return last;
+ }
+
+ @Override
+ public void remove() {
+ // Not remove(Object), which would edit orderedKeys while this
iterator walks it.
+ iterator.remove();
+ OrderedProperties.super.remove(last);
+ }
Review Comment:
`orderedKeysIterator().remove()` mutates `orderedKeys` via
`iterator.remove()` without holding the `OrderedProperties` monitor, while
other `orderedKeys` mutations are done inside `synchronized` methods. This can
race with `toString()`, `keys()`, `put()`, etc. (which assume `orderedKeys` is
only modified under that monitor) and can temporarily desync order/mappings or
trigger `ConcurrentModificationException` during otherwise-synchronized
operations.
Synchronize the combined ordered-key + backing-map removal on
`OrderedProperties.this` so all `orderedKeys` writes stay under the same lock.
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