Read views - box.read_view.list (#3445)

Author: andreyaksenov

doc/reference/reference_lua/box.rst

@@ -27,6 +27,7 @@ with ``box``, with no arguments. The ``box`` module contains:
     box_error
     box_index
     box_info
+    box_read_view
     box_schema
     box_schema_sequence
     box_session

doc/reference/reference_lua/box_read_view.rst

@@ -0,0 +1,26 @@
+-------------------------------------------------------------------------------
+Submodule box.read_view
+-------------------------------------------------------------------------------
+
+The box.read_view submodule contains functions related to read views.
+
+..  container:: table
+
+    ..  rst-class:: left-align-column-1
+    ..  rst-class:: left-align-column-2
+
+    ..  list-table::
+        :widths: 25 75
+        :header-rows: 1
+
+        *   - Name
+            - Use
+
+        *  - :doc:`./box_read_view/list`
+           - Return an array of all active database read views.
+
+
+..  toctree::
+    :hidden:
+
+    box_read_view/list

doc/reference/reference_lua/box_read_view/list.rst

@@ -0,0 +1,48 @@
+.. _reference_lua-box_read_view_list:
+
+===============================================================================
+box.read_view.list()
+===============================================================================
+
+.. function:: read_view.list()
+
+    Return an array of all active database read views.
+    This array might include the following read view types:
+
+    *   `read views <https://www.tarantool.io/en/enterprise_doc/read_views/>`_ created by application code (available in Tarantool Enterprise only)
+
+    *   system read views (used, for example, to make a :ref:`checkpoint <book_cfg_checkpoint_daemon>`
+        or join a new :ref:`replica <replication-architecture>`)
+
+    Read views created by application code also have the ``space`` field.
+    The field lists all spaces available in a read view,
+    and may be used like a read view object returned by ``box.read_view.open()``.
+
+    .. NOTE::
+
+        ``read_view.list()`` also contains read views created using the
+        `C API <https://www.tarantool.io/en/enterprise_doc/read_views/c_api/>`_ (``box_raw_read_view_new()``).
+        Note that you cannot access database spaces included in such views from Lua.
+
+
+    **Example:**
+
+    .. code-block:: tarantoolsession
+
+        tarantool> box.read_view.list()
+        ---
+        - - timestamp: 1138.98706933
+            signature: 47
+            is_system: false
+            status: open
+            vclock: &0 {1: 47}
+            name: read_view1
+            id: 1
+          - timestamp: 1172.202995842
+            signature: 49
+            is_system: false
+            status: open
+            vclock: &1 {1: 49}
+            name: read_view2
+            id: 2
+        ...