Shrink level hash tables too.

It's important to have O(1) begin() on these hash tables, because it's used in search.
andrusha97 · Oct 20, 2017 · a02982a · a02982a
1 parent 88cc86d
commit a02982a
Showing 1 changed file with 6 additions and 2 deletions.
diff --git a/include/hnsw/index.hpp b/include/hnsw/index.hpp
@@ -217,14 +217,18 @@ struct hnsw_index {
 
         level_it->second.erase(key);
 
+        // Shrink the hash table when it becomes too sparse
+        // (to reduce memory usage and ensure linear complexity for iteration).
+        if (4 * level_it->second.load_factor() < level_it->second.max_load_factor()) {
+            level_it->second.rehash(size_t(2 * level_it->second.size() / level_it->second.max_load_factor()));
+        }
+
         if (level_it->second.empty()) {
             levels.erase(level_it);
         }
 
         nodes.erase(node_it);
 
-        // Shrink the hash table when it becomes too sparse
-        // (to reduce memory usage and ensure linear complexity for iteration).
         if (4 * nodes.load_factor() < nodes.max_load_factor()) {
             nodes.rehash(size_t(2 * nodes.size() / nodes.max_load_factor()));
         }