presto-main/src/main/java/io/prestosql/operator/WindowOperator.java/SpillablePagesToPagesIndexes/finishRevokeMemory
class SpillablePagesToPagesIndexes:        void finishRevokeMemory()
        {
            if (!spillInProgress.isPresent()) {
                // Same spill iteration can be finished first by Driver (via WindowOperator#finishMemoryRevoke) and then by SpillablePagesToPagesIndexes#process(..)
                return;
            }

            checkSuccess(spillInProgress.get(), "spilling failed");
            spillInProgress = Optional.empty();

            // No memory to reclaim
            if (localRevocableMemoryContext.getBytes() == 0) {
                return;
            }

            inMemoryPagesIndexWithHashStrategies.pagesIndex.clear();
            updateMemoryUsage(false);
        }