Add async lock for atomic graph database operations

• Introduced graph_db_lock mechanism
• Ensured atomic node/edge merge and insert operation

lightrag/operate.py

@@ -519,19 +519,24 @@ async def extract_entities(
         for k, v in m_edges.items():
             maybe_edges[tuple(sorted(k))].extend(v)
 
-    all_entities_data = await asyncio.gather(
-        *[
-            _merge_nodes_then_upsert(k, v, knowledge_graph_inst, global_config)
-            for k, v in maybe_nodes.items()
-        ]
-    )
+    from .kg.shared_storage import get_graph_db_lock
+    graph_db_lock = get_graph_db_lock(enable_logging = True)
+    
+    # Ensure that nodes and edges are merged and upserted atomically
+    async with graph_db_lock:
+        all_entities_data = await asyncio.gather(
+            *[
+                _merge_nodes_then_upsert(k, v, knowledge_graph_inst, global_config)
+                for k, v in maybe_nodes.items()
+            ]
+        )
 
-    all_relationships_data = await asyncio.gather(
-        *[
-            _merge_edges_then_upsert(k[0], k[1], v, knowledge_graph_inst, global_config)
-            for k, v in maybe_edges.items()
-        ]
-    )
+        all_relationships_data = await asyncio.gather(
+            *[
+                _merge_edges_then_upsert(k[0], k[1], v, knowledge_graph_inst, global_config)
+                for k, v in maybe_edges.items()
+            ]
+        )
 
     if not (all_entities_data or all_relationships_data):
         log_message = "Didn't extract any entities and relationships."