Topic/communication engine as a component

CMakeLists.txt

@@ -168,8 +168,10 @@ mark_as_advanced(PARSEC_SCHED_DEPS_MASK)
 mark_as_advanced(PARSEC_DIST_THREAD PARSEC_DIST_PRIORITIES)
 option(PARSEC_DIST_WITH_MPI
   "Build PaRSEC for distributed memory with MPI backend (conflicts all other backends)" ON)
-if(PARSEC_DIST_WITH_MPI AND 0)
-  message(FATAL_ERROR "PARSEC_DIST_WITH_MPI and PARSEC_DIST_WITH_OTHER are mutually exclusive, please select only one")
+option(PARSEC_DIST_WITH_UCX
+  "Build PaRSEC for distributed memory with UCX backend bootstrapped by PMIx" OFF)
+if(PARSEC_DIST_WITH_MPI AND PARSEC_DIST_WITH_UCX)
+  message(FATAL_ERROR "The UCX backend currently requires PARSEC_DIST_WITH_MPI=OFF because the MPI build still exposes MPI_Datatype in the public datatype ABI")
 endif()
 option(PARSEC_MPI_IS_GPU_AWARE
        "Build PaRSEC assuming the MPI library is GPU-aware, aka. can move data directly to and from GPU memory.\
@@ -647,6 +649,17 @@ if( BUILD_PARSEC )
     endif (NOT MPI_C_FOUND)
     list(APPEND EXTRA_LIBS ${MPI_C_LIBRARIES})
   endif (PARSEC_DIST_WITH_MPI)
+  if (PARSEC_DIST_WITH_UCX)
+    find_package(PkgConfig REQUIRED)
+    pkg_check_modules(PARSEC_UCX REQUIRED ucx)
+    pkg_check_modules(PARSEC_PMIX REQUIRED pmix)
+    set(PARSEC_HAVE_UCX TRUE)
+    set(PARSEC_HAVE_PMIX TRUE)
+    include_directories(BEFORE ${PARSEC_UCX_INCLUDE_DIRS} ${PARSEC_PMIX_INCLUDE_DIRS})
+    link_directories(${PARSEC_UCX_LIBRARY_DIRS} ${PARSEC_PMIX_LIBRARY_DIRS})
+    list(APPEND EXTRA_INCLUDES ${PARSEC_UCX_INCLUDE_DIRS} ${PARSEC_PMIX_INCLUDE_DIRS})
+    list(APPEND EXTRA_LIBS ${PARSEC_UCX_LIBRARIES} ${PARSEC_PMIX_LIBRARIES})
+  endif (PARSEC_DIST_WITH_UCX)
   #
   # Check to see if
   #     support for MPI 2.0 is available

parsec/CMakeLists.txt

@@ -120,6 +120,7 @@ set(SOURCES
   private_mempool.c
   remote_dep.c
   parsec_comm_engine.c
+  datatype/datatype_module.c
   scheduling.c
   compound.c
   vpmap.c
@@ -130,16 +131,13 @@ set(SOURCES
 if( PARSEC_PROF_TRACE )
   list(APPEND SOURCES dictionary.c)
 endif( PARSEC_PROF_TRACE )
-if( PARSEC_HAVE_MPI )
+if( PARSEC_HAVE_MPI OR PARSEC_HAVE_UCX )
   list(APPEND SOURCES
-    parsec_mpi_funnelled.c
-    remote_dep_mpi.c)
-endif( PARSEC_HAVE_MPI )
-if( NOT MPI_C_FOUND )
+    remote_dep_comm.c)
+endif( PARSEC_HAVE_MPI OR PARSEC_HAVE_UCX )
+if( NOT PARSEC_HAVE_MPI )
   list(APPEND SOURCES datatype/datatype.c)
-else( NOT MPI_C_FOUND )
-  list(APPEND SOURCES datatype/datatype_mpi.c)
-endif( NOT MPI_C_FOUND )
+endif( NOT PARSEC_HAVE_MPI )
 list(APPEND SOURCES parsec_hwloc.c)
 
 if( PARSEC_PROF_GRAPHER )
@@ -310,6 +308,7 @@ if( BUILD_PARSEC )
           ${CMAKE_CURRENT_SOURCE_DIR}/include/parsec/parsec_config_bottom.h
           ${CMAKE_CURRENT_SOURCE_DIR}/include/parsec/data_distribution.h
           ${CMAKE_CURRENT_SOURCE_DIR}/datatype.h
+          ${CMAKE_CURRENT_SOURCE_DIR}/datatype_module.h
           ${CMAKE_CURRENT_SOURCE_DIR}/profiling.h
           ${CMAKE_CURRENT_SOURCE_DIR}/dictionary.h
           ${CMAKE_CURRENT_SOURCE_DIR}/data.h

parsec/data.c

@@ -635,7 +635,7 @@ static void parsec_arena_datatype_construct(parsec_object_t *obj) {
     adt->ht_item.next_item  = NULL; /* keep Coverity happy */
     adt->ht_item.hash64     = 0;    /* keep Coverity happy */
     adt->ht_item.key        = 0;    /* keep Coverity happy */
-    adt->opaque_dtt         = NULL;
+    adt->opaque_dtt         = PARSEC_DATATYPE_NULL;
 }
 
 static void parsec_arena_datatype_destruct(parsec_object_t *obj) {

parsec/datatype.h

@@ -2,6 +2,7 @@
  * Copyright (c) 2015-2021 The University of Tennessee and The University
  *                         of Tennessee Research Foundation.  All rights
  *                         reserved.
+ * Copyright (c) 2026      NVIDIA Corporation.  All rights reserved.
  */
 
 #ifndef PARSEC_DATATYPE_H_HAS_BEEN_INCLUDED
@@ -66,9 +67,12 @@ typedef intptr_t  parsec_datatype_t;
 BEGIN_C_DECLS
 
 /**
- * Map the datatype creation to the well designed and well known MPI datatype
- * API. The datatype support remains extremely basic, providing API only for
- * basic datatypes and functions to mix them together.
+ * Datatype portability API used by communication and data-movement engines.
+ *
+ * The public parsec_type_* functions are stable entry points.  Their
+ * implementation is selected by the active communication backend, so MPI builds
+ * can keep MPI datatypes while other transports can provide another
+ * representation.
  */
 int parsec_type_size(parsec_datatype_t type,
                      int *size);
@@ -120,7 +124,8 @@ int parsec_type_match(parsec_datatype_t dtt1,
 /**
  * Routine to check if a datatype is contiguous.
  * @param[in] parsec_datatype_t datatype
- * @return PARSEC_SUCCESS if it was created with MPI_Type_contiguous, PARSEC_ERROR otherwise.
+ * @return PARSEC_SUCCESS if the selected backend recognizes it as contiguous,
+ *         PARSEC_ERROR otherwise.
  */
 int parsec_type_contiguous(parsec_datatype_t dtt);
 END_C_DECLS