Downgrade run-after-mutation error to a log warning.

This is to ease the transition to the C API. Some tests currently mutate the
graph after running it but currently pass. This error was meant to guard
against existing behavior, so it's not a regression to make it a warning
instead for now.

PiperOrigin-RevId: 189395472

1 files changed, 9 insertions, 8 deletions

diff --git a/tensorflow/c/c_api_internal.h b/tensorflow/c/c_api_internal.h
index e885a69927..95652a1137 100644
--- a/tensorflow/c/c_api_internal.h
+++ b/tensorflow/c/c_api_internal.h
@@ -84,19 +84,20 @@ struct TF_Graph {
   std::unordered_map<tensorflow::string, tensorflow::Node*> name_map
       GUARDED_BY(mu);
 
-  // The keys of this map are all the active sessions using this graph.
-  // Each value is the current "runnability" status of the corresponding
-  // session. Under normal conditions all statuses are Status::OK(), but
-  // if some operation is mutated after it was run by a session (this
-  // is detected in RecordMutation function), that session is no longer
-  // safe to run. Its status will contain the error that will be returned
-  // to the user, should she try running this session.
+  // The keys of this map are all the active sessions using this graph. Each
+  // value records whether the graph has been mutated since the corresponding
+  // session has been run (this is detected in RecordMutation function). If the
+  // string is empty, no mutation has occurred. Otherwise the string is a
+  // description of the mutation suitable for returning to the user.
   //
   // Sessions are added to this map in TF_NewSession, and removed in
   // TF_DeleteSession.
   // TF_Graph may only / must be deleted when
   //   sessions.size() == 0 && delete_requested == true
-  tensorflow::gtl::FlatMap<TF_Session*, tensorflow::Status> sessions
+  //
+  // TODO(b/74949947): mutations currently trigger a warning instead of a bad
+  // status, this should be reverted when possible.
+  tensorflow::gtl::FlatMap<TF_Session*, tensorflow::string> sessions
       GUARDED_BY(mu);
   bool delete_requested GUARDED_BY(mu);  // set true by TF_DeleteGraph