detail::graph: Add shutdown capability

In the existing graph, when the shutdown was simply a release. However,
any outstanding actions would trigger warnings (because released graphs
aren't supposed to still have actions being passed around), which would
sometimes be visible at the end of an application.

This is a safer solution than simply releasing, because it explicitly
sets a shutdown flag that all graph-affecting functions (property
propagation and action handling) respect. Once the flag is set, the
graph can no longer be booted up again.

1 files changed, 12 insertions, 4 deletions

diff --git a/host/lib/include/uhdlib/rfnoc/graph.hpp b/host/lib/include/uhdlib/rfnoc/graph.hpp
index 286f2303f..c7b06d636 100644
--- a/host/lib/include/uhdlib/rfnoc/graph.hpp
+++ b/host/lib/include/uhdlib/rfnoc/graph.hpp
@@ -63,6 +63,15 @@ public:
      */
     void release();
 
+    /*! Shutdown graph: Permenanently release
+     *
+     * This will release the graph permanently and safely. All ongoing property
+     * and action handling is completed and then disabled (this means that
+     * calling shutdown while blocks are still working will cause actions to not
+     * get delivered).
+     */
+    void shutdown();
+
     /*! Return a list of all edges
      */
     std::vector<graph_edge_t> enumerate_edges();
@@ -271,16 +280,15 @@ private:
     //! Flag to ensure serialized handling of actions
     std::atomic_flag _action_handling_ongoing;
 
-    //! Mutex for to avoid the user from sending one message before another
-    // message is sent
-    std::recursive_mutex _action_mutex;
-
     //! Changes to the release/commit state of the graph are locked with this mutex
     std::recursive_mutex _release_mutex;
 
     //! This counter gets decremented everytime commit() is called. When zero,
     // the graph is committed.
     size_t _release_count{1};
+
+    //! A flag if the graph has shut down. Is protected by _release_mutex
+    bool _shutdown{false};
 };