Method insert

fdbserver/VersionedBTree.actor.cpp:5488–5516

Find or create a mutation buffer boundary for bound and return an iterator to it

		// Find or create a mutation buffer boundary for bound and return an iterator to it
		iterator insert(KeyRef boundary) {
			// Find the first split point in buffer that is >= key
			// Since the initial state of the mutation buffer contains the range '' through
			// the maximum possible key, our search had to have found something so we
			// can assume the iterator is valid.
			iterator ib = mutations.lower_bound(boundary);

			// If we found the boundary we are looking for, return its iterator
			if (ib.key() == boundary) {
				return ib;
			}

			// ib is our insert hint.  Copy boundary into arena and insert boundary into buffer
			boundary = KeyRef(arena, boundary);
			ib = mutations.insert(ib, { boundary, RangeMutation() });

			// ib is certainly > begin() because it is guaranteed that the empty string
			// boundary exists and the only way to have found that is to look explicitly
			// for it in which case we would have returned above.
			iterator iPrevious = ib;
			--iPrevious;
			// If the range we just divided was being cleared, then the dividing boundary key and range after it must
			// also be cleared
			if (iPrevious.mutation().clearAfterBoundary) {
				ib.mutation().clearAll();
			}

			return ib;
		}
	};
#define USE_ART_MUTATION_BUFFER 1