Fix sexp_of_device/stream to break cyclicity

arrayjit/lib/backend_intf.ml

@@ -79,42 +79,78 @@ module type Device_config = sig
   val name : string
 end
 
-type ('buffer_ptr, 'dev, 'runner, 'event) device = {
+
+type ('buffer_ptr, 'dev, 'runner, 'event) device_ref = {
+  dev : 'dev;
+  ordinal : int;
+  mutable shared_merge_buffer : 'buffer_ptr buffer option;
+  mutable scheduled_shared_merge_node : (Tnode.t * 'event option) option;
+  mutable latest_stream_id : int;
+  released : Utils.atomic_bool;
+  cross_stream_candidates : 'buffer_ptr Hashtbl.M(Tnode).t;
+  owner_stream : ('buffer_ptr, 'dev, 'runner, 'event) stream_ref Hashtbl.M(Tnode).t;
+  shared_writer_streams :
+    (('buffer_ptr, 'dev, 'runner, 'event) stream_ref * 'event) list Hashtbl.M(Tnode).t;
+  host_reading_streams :
+    (('buffer_ptr, 'dev, 'runner, 'event) stream_ref * 'event) list Hashtbl.M(Tnode).t;
+  host_writing_streams :
+    (('buffer_ptr, 'dev, 'runner, 'event) stream_ref * 'event) list Hashtbl.M(Tnode).t;
+}
+
+and ('buffer_ptr, 'dev, 'runner, 'event) stream_ref = {
+  device : ('buffer_ptr, 'dev, 'runner, 'event) device_ref;
+  runner : 'runner;
+  merge_buffer : 'buffer_ptr buffer option ref;
+  mutable scheduled_merge_node : Tnode.t option;
+  stream_id : int;
+  mutable allocated_buffer : 'buffer_ptr buffer option;
+  updating_for : 'event Hashtbl.M(Tnode).t;
+  mutable updating_for_merge_buffer : (Tnode.t * 'event) option;
+  reader_streams :
+    (('buffer_ptr, 'dev, 'runner, 'event) stream_ref * 'event) list Hashtbl.M(Tnode).t;
+}
+
+let sexp_of_device_ref _ _ _ _ device = [%sexp_of: string * int] ("ordinal", device.ordinal)
+let sexp_of_stream_ref _ _ _ _ stream = [%sexp_of: string * int] ("stream_id", stream.stream_id)
+let equal_stream_ref s1 s2 = s1.stream_id = s2.stream_id && s1.device.ordinal = s2.device.ordinal
+
+type ('buffer_ptr, 'dev, 'runner, 'event) device =
+      ('buffer_ptr, 'dev, 'runner, 'event) device_ref = {
   dev : 'dev;
   ordinal : int;
   mutable shared_merge_buffer : 'buffer_ptr buffer option;
       (** Depending on backend implementations, either the currently used cross-stream merge buffer,
           or the one most recently scheduled. *)
   mutable scheduled_shared_merge_node : (Tnode.t * 'event option) option;
-      (** The tensor node that was most recently scheduled to be in the cross-stream merge buffer,
-          and its readiness event. *)
+      (** The tensor node that was most recently scheduled to be in the cross-stream merge buffer. *)
   mutable latest_stream_id : int;
   released : Utils.atomic_bool;
   cross_stream_candidates : 'buffer_ptr Hashtbl.M(Tnode).t;
       (** Freshly created arrays that might be shared across streams. The map can both grow and
           shrink. *)
-  owner_stream : ('buffer_ptr, 'dev, 'runner, 'event) stream Hashtbl.M(Tnode).t;
+  owner_stream : ('buffer_ptr, 'dev, 'runner, 'event) stream_ref Hashtbl.M(Tnode).t;
       (** The stream owning a given node. This map can only grow. Currently, if the memory mode of a
           node is inferred, only this stream will modify a cross-stream shared array. But memory
           modes can also be set manually. *)
   shared_writer_streams :
-    (('buffer_ptr, 'dev, 'runner, 'event) stream * 'event) list Hashtbl.M(Tnode).t;
+    (('buffer_ptr, 'dev, 'runner, 'event) stream_ref * 'event) list Hashtbl.M(Tnode).t;
       (** The streams that most recently have been scheduled to update (write to) a
           cross-stream-shared node, and the associated update completion event. The completed events
           are removed opportunistically. *)
   host_reading_streams :
-    (('buffer_ptr, 'dev, 'runner, 'event) stream * 'event) list Hashtbl.M(Tnode).t;
+    (('buffer_ptr, 'dev, 'runner, 'event) stream_ref * 'event) list Hashtbl.M(Tnode).t;
       (** The streams that most recently have been reading from a node's on-host array. The
           completed events are removed opportunistically. *)
   host_writing_streams :
-    (('buffer_ptr, 'dev, 'runner, 'event) stream * 'event) list Hashtbl.M(Tnode).t;
+    (('buffer_ptr, 'dev, 'runner, 'event) stream_ref * 'event) list Hashtbl.M(Tnode).t;
       (** The streams that most recently have been writing to a node's on-host array. The completed
           events are removed opportunistically. *)
 }
 [@@deriving sexp_of]
 
-and ('buffer_ptr, 'dev, 'runner, 'event) stream = {
-  device : ('buffer_ptr, 'dev, 'runner, 'event) device;
+type ('buffer_ptr, 'dev, 'runner, 'event) stream =
+      ('buffer_ptr, 'dev, 'runner, 'event) stream_ref = {
+  device : ('buffer_ptr, 'dev, 'runner, 'event) device_ref;
   runner : 'runner;
   merge_buffer : 'buffer_ptr buffer option ref;
       (** Depending on backend implementations, either the currently used merge buffer, or the one
@@ -124,17 +160,18 @@ and ('buffer_ptr, 'dev, 'runner, 'event) stream = {
   stream_id : int;  (** An ID unique within the device. *)
   mutable allocated_buffer : 'buffer_ptr buffer option;
   updating_for : 'event Hashtbl.M(Tnode).t;
-      (* The completion event for updating (writing to) a node via this stream, if any. *)
+  (* The completion event for updating (writing to) a node via this stream, if any. *)
   mutable updating_for_merge_buffer : (Tnode.t * 'event) option;
       (** Like {!field-updating_for}, but for the merge buffer. *)
-  reader_streams : (('buffer_ptr, 'dev, 'runner, 'event) stream * 'event) list Hashtbl.M(Tnode).t;
+  reader_streams :
+    (('buffer_ptr, 'dev, 'runner, 'event) stream_ref * 'event) list Hashtbl.M(Tnode).t;
       (** The streams, other than this stream, that most recently have been reading from a node in
           this stream's context, and the associated use completion events. The completed events are
           removed opportunistically. *)
 }
 [@@deriving sexp_of]
 
-let equal_stream s1 s2 = s1.stream_id = s2.stream_id && s1.device.ordinal = s2.device.ordinal
+let equal_stream = equal_stream_ref
 
 type ('buffer_ptr, 'stream) context = {
   stream : 'stream;