feat(api): introduce Flow.close() to replace cocoindex.remove_flow() (#829)

Author: georgeh0

docs/docs/core/flow_def.mdx

@@ -46,10 +46,10 @@ demo_flow = cocoindex.add_flow_def("DemoFlow", demo_flow_def)
 In both cases, `demo_flow` will be an object with `cocoindex.Flow` class type.
 See [Flow Running](/docs/core/flow_methods) for more details on it.
 
-Sometimes you no longer want to keep states of the flow in memory. We provide a `cocoindex.remove_flow()` method for this purpose:
+Sometimes you no longer want to keep states of the flow in memory. We provide a `close()` method for this purpose:
 
 ```python
-cocoindex.remove_flow(demo_flow)
+demo_flow.close()
 ```
 
 After it's called, `demo_flow` becomes an invalid object, and you should not call any methods of it.

docs/docs/core/flow_methods.mdx

@@ -39,7 +39,7 @@ It creates a `demo_flow` object in `cocoindex.Flow` type.
 For a flow, its persistent backends need to be ready before it can run, including:
 
 *   [Internal storage](/docs/core/basics#internal-storage) for CocoIndex.
-*   Backend entities for targets exported by the flow, e.g. a table (in relational databases), a collection (in some vector databases), etc.
+*   Backend resources for targets exported by the flow, e.g. a table (in relational databases), a collection (in some vector databases), etc.
 
 The desired state of the backends for a flow is derived based on the flow definition itself.
 CocoIndex supports two types of actions to manage the persistent backends automatically:
@@ -104,7 +104,7 @@ cocoindex.drop_all_flows(report_to_stdout=True)
 
 After dropping the flow, the in-memory `cocoindex.Flow` instance is still valid, and you can call setup methods on it again.
 
-If you want to remove the flow from the current process, you can call `cocoindex.remove_flow(demo_flow)` to do so (see [related doc](/docs/core/flow_def#entry-point)).
+If you want to remove the flow from the current process, you can call `demo_flow.close()` to do so (see [related doc](/docs/core/flow_def#entry-point)).
 
 :::
 

python/cocoindex/flow.py

@@ -798,7 +798,7 @@ def drop(self, report_to_stdout: bool = False) -> None:
         The current instance is still valid after it's called.
         For example, you can still call `setup()` after it, to setup the persistent backends again.
 
-        Call `cocoindex.remove_flow()` if you want to remove the flow from the current process.
+        Call `close()` if you want to remove the flow from the current process.
         """
         execution_context.run(self.drop_async(report_to_stdout=report_to_stdout))
 
@@ -810,6 +810,18 @@ async def drop_async(self, report_to_stdout: bool = False) -> None:
             report_to_stdout=report_to_stdout
         )
 
+    def close(self) -> None:
+        """
+        Close the flow. It will remove the flow from the current process to free up resources.
+        After it's called, methods of the flow should no longer be called.
+
+        This will NOT touch the persistent backends of the flow.
+        """
+        _engine.remove_flow_context(self.full_name)
+        self._lazy_engine_flow = None
+        with _flows_lock:
+            del _flows[self.name]
+
 
 def _create_lazy_flow(
     name: str | None, fl_def: Callable[[FlowBuilder, DataScope], None]
@@ -855,15 +867,9 @@ def add_flow_def(name: str, fl_def: Callable[[FlowBuilder, DataScope], None]) ->
 
 def remove_flow(fl: Flow) -> None:
     """
-    Remove a flow from the current process to free up resources.
-    After it's called, methods of the flow should no longer be called.
-
-    This will NOT touch the persistent backends of the flow.
+    DEPRECATED: Use `Flow.close()` instead.
     """
-    _engine.remove_flow_context(fl.full_name)
-    fl._lazy_engine_flow = None  # pylint: disable=protected-access
-    with _flows_lock:
-        del _flows[fl.name]
+    fl.close()
 
 
 def flow_def(