1 files changed, 44 insertions, 0 deletions
diff --git a/src/rocksdb/table/iter_heap.h b/src/rocksdb/table/iter_heap.h
new file mode 100644
index 000000000..6ad94be9b
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+++ b/src/rocksdb/table/iter_heap.h
@@ -0,0 +1,44 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+
+#pragma once
+
+#include "db/dbformat.h"
+#include "table/iterator_wrapper.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// When used with std::priority_queue, this comparison functor puts the
+// iterator with the max/largest key on top.
+class MaxIteratorComparator {
+ public:
+  MaxIteratorComparator(const InternalKeyComparator* comparator)
+      : comparator_(comparator) {}
+
+  bool operator()(IteratorWrapper* a, IteratorWrapper* b) const {
+    return comparator_->Compare(a->key(), b->key()) < 0;
+  }
+
+ private:
+  const InternalKeyComparator* comparator_;
+};
+
+// When used with std::priority_queue, this comparison functor puts the
+// iterator with the min/smallest key on top.
+class MinIteratorComparator {
+ public:
+  MinIteratorComparator(const InternalKeyComparator* comparator)
+      : comparator_(comparator) {}
+
+  bool operator()(IteratorWrapper* a, IteratorWrapper* b) const {
+    return comparator_->Compare(a->key(), b->key()) > 0;
+  }
+
+ private:
+  const InternalKeyComparator* comparator_;
+};
+
+}  // namespace ROCKSDB_NAMESPACE