C++ API remove mgp::memory usage note (#1016)

pages/custom-query-modules/cpp/cpp-api.md

@@ -6,30 +6,36 @@ description: Get your hands on the API documentation for mgp.hpp, covering decla
 # Query modules C++ API
 
 This is the API documentation for `mgp.hpp`, which contains declarations of all
-functions in the C++ API for implementing query module procedures and functions.
-The source file can be found in the Memgraph installation directory, under
-`/usr/include/memgraph`.
+functions in the C++ API for implementing query module procedures and
+functions. The source file can be found in the Memgraph installation directory,
+under `/usr/include/memgraph`.
 
-To see how to implement query modules in C++, take a look at
-[the example we provided](/custom-query-modules/python/python-example).
+To see how to implement query modules in C++, take a look at [the example we
+provided](/custom-query-modules/python/python-example).
 
 If you install any C++ modules after running Memgraph, you’ll need to [load
-them into Memgraph](/custom-query-modules/manage-query-modules#loading-query-modules) or restart
-Memgraph in order to use them.
+them into
+Memgraph](/custom-query-modules/manage-query-modules#loading-query-modules) or
+restart Memgraph in order to use them.
 
 ## Functions and procedures
 
-With this API it’s possible to extend your Cypher queries with **functions** and **procedures** with
-`AddProcedure` and `AddFunction`.
+With this API it’s possible to extend your Cypher queries with **functions**
+and **procedures** with `AddProcedure` and `AddFunction`.
 
-The API needs memory access to add procedures and functions, this can be done with either `mgp::MemoryDispatcherGuard guard(memory);` or `mgp::memory = memory;`, where the use of the former is advised since `mgp::memory = memory;` is not thread-safe and will be deprecated in the future.
+The API needs memory access to add procedures and functions, this can be done
+with `mgp::MemoryDispatcherGuard guard(memory);`. Old code used `mgp::memory =
+memory;`, but this is not thread-safe and has been deprecated. v2.18.1 onwards
+you should modify your C++ modules and recompile. v2.21 onwards setting
+`mgp::memory` will cause a compilation error, so the guard has to be used.
 
-Functions are simple operations that return a single value and can be used in any expression or predicate.
-
-Procedures are more complex computations that may modify the graph, and their output is available to
-later processing steps in your query. A procedure may only be run from `CALL` clauses.
-The output is a stream of **records** that is made accessible with a `YIELD` clause.
+Functions are simple operations that return a single value and can be used in
+any expression or predicate.
 
+Procedures are more complex computations that may modify the graph, and their
+output is available to later processing steps in your query. A procedure may
+only be run from `CALL` clauses. The output is a stream of **records** that is
+made accessible with a `YIELD` clause.
 
 ### AddProcedure
 

pages/custom-query-modules/cpp/cpp-example.mdx

@@ -392,13 +392,16 @@ void RandomWalk(mgp_list *args, mgp_graph *memgraph_graph, mgp_result *result, m
 
 <Callout type="error">
 
-As `mgp::memory` is a global object, that means all of the procedures and
+`mgp::memory` was a global object, that meant all of the procedures and
 functions in a single shared library will refer to the same `mgp::memory`
-object. As a result, calling such callables simultaneously from multiple threads
-will lead to incorrect memory usage. This also includes the case when the same
-callable is called from different user sessions. This is a constraint when using
-`mgp::memory` so the use of the thread-safe `MemoryDispatcherGuard guard(memory)`
-is advised instead.
+object. As a result, calling such callables simultaneously from multiple
+threads will lead to incorrect memory usage. This also includes the case when
+the same callable is called from different user sessions. For some versions of
+memgraph this was deprecated and the use of the thread-safe
+`MemoryDispatcherGuard guard(memory)` is advised instead. Its has now been
+removed and C++ modules should be recompiled for v2.18.1+. v2.21 onwards
+setting `mgp::memory` will cause a compilation error, so the guard has to be
+used.
 
 </Callout>