ctubbsii commented on a change in pull request #2347:
URL: https://github.com/apache/accumulo/pull/2347#discussion_r745061737
##########
File path:
core/src/main/java/org/apache/accumulo/core/iterators/SortedMapIterator.java
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@@ -36,28 +37,40 @@
*
* Note that this class is intended as an in-memory replacement for
RFile$Reader, so its behavior
* reflects the same assumptions; namely, that this iterator is not
responsible for respecting the
- * columnFamilies passed into seek().
+ * columnFamilies passed into seek(). If you want a Map-backed Iterator that
returns only sought
+ * CFs, construct a new ColumnFamilySkippingIterator(new
SortedMapIterator(map)).
+ *
+ * @see org.apache.accumulo.core.iterators.ColumnFamilySkippingIterator
*/
-public class SortedMapIterator implements SortedKeyValueIterator<Key,Value> {
+public class SortedMapIterator implements InterruptibleIterator {
private Iterator<Entry<Key,Value>> iter;
private Entry<Key,Value> entry;
private SortedMap<Key,Value> map;
private Range range;
+ private AtomicBoolean interruptFlag;
Review comment:
It's not a performance thing. It's an implementation injection mechanism
(see where we're notifying the iterators by changing the value in the scan
code: `grep -lR 'interruptFlag.set(true)' .`. AtomicBoolean is being used like
a BooleanSupplier. This was probably fine at one point, since BooleanSupplier
was introduced in Java 8, and before that, AtomicBoolean was an attractive
alternative to a built-in supplier. But, having the type be AtomicBoolean
implies atomicity, and that can be confusing, since atomicity guarantees are
clearly broken by having a setter that can swap out the reference itself in
addition to the value. We're not actually relying on the atomicity guarantees
in these cases, though, as far as I can tell, so BooleanSupplier would suffice
as the type.
Your code above wouldn't work. I had a similar idea initially
(`this.interruptFlag.set(flag.get())`). However, it's not sufficient to set the
value. We need to set the containing object reference, so we can communicate
the change in value when the caller updates the source.
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