leventov commented on a change in pull request #7938: locking in Theta sketch
buffer aggregator
URL: https://github.com/apache/incubator-druid/pull/7938#discussion_r317982339
##########
File path:
extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchBufferAggregator.java
##########
@@ -54,32 +59,58 @@ public void init(ByteBuffer buf, int position)
createNewUnion(buf, position, false);
}
+ /**
+ * This method uses locks because it can be used during indexing,
+ * and Druid can call aggregate() and get() concurrently
+ * https://github.com/apache/incubator-druid/pull/3956
+ */
@Override
public void aggregate(ByteBuffer buf, int position)
{
Object update = selector.getObject();
if (update == null) {
return;
}
-
- Union union = getOrCreateUnion(buf, position);
- SketchAggregator.updateUnion(union, update);
+ final Lock lock =
stripedLock.getAt(StripedLockHelper.lockIndex(position)).writeLock();
+ lock.lock();
+ try {
+ Union union = getOrCreateUnion(buf, position);
+ SketchAggregator.updateUnion(union, update);
+ }
+ finally {
+ lock.unlock();
+ }
}
+ /**
+ * This method uses locks because it can be used during indexing,
+ * and Druid can call aggregate() and get() concurrently
+ * https://github.com/apache/incubator-druid/pull/3956
+ * The returned sketch is a separate instance of Sketch
+ * representing the current state of the aggregation, and is not affected by
consequent
+ * aggregate() calls
Review comment:
Please make `{@link #aggregate}` a Javadoc link
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