Merge pull request #25 from danclaudino/hpc_virt_update

Added shots to HPC virtualization

CMakeLists.txt

@@ -151,7 +151,9 @@ add_compile_flags_if_supported(-Wno-maybe-uninitialized)
 # Check MPI status
 # if MPI_CXX_COMPILER is not empty and XACC_ENABLE_MPI is set
 # turn MPI_ENABLED on
-if(NOT MPI_CXX_COMPILER STREQUAL "" AND XACC_ENABLE_MPI)
+# Update: we don't really need to give the path to the compiler
+# because if MPI is found, MPI_CXX_COMPILER is populated
+if(XACC_ENABLE_MPI)
   find_package(MPI)
 
   if(MPI_FOUND)

quantum/plugins/decorators/hpc-virtualization/MPIProxy.cpp

@@ -4,14 +4,25 @@ Copyright (C) 2018-2021 Dmitry I. Lyakh (Liakh)
 Copyright (C) 2018-2021 Oak Ridge National Laboratory (UT-Battelle) **/
 
 #include "MPIProxy.hpp"
-
-#include "mpi.h"
-
 #include <cstdlib>
-
 #include <iostream>
 #include <algorithm>
 
+template <>
+MPI_Datatype MPIDataTypeResolver<int>::getMPIDatatype() {
+    return MPI_INT;
+}
+
+template <>
+MPI_Datatype MPIDataTypeResolver<double>::getMPIDatatype() {
+    return MPI_DOUBLE;
+}
+
+template <>
+MPI_Datatype MPIDataTypeResolver<char>::getMPIDatatype() {
+    return MPI_CHAR;
+}
+
 namespace xacc {
 
 //Temporary buffers:

quantum/plugins/decorators/hpc-virtualization/MPIProxy.hpp

@@ -9,6 +9,13 @@ Copyright (C) 2018-2021 Oak Ridge National Laboratory (UT-Battelle) **/
 #include <vector>
 #include <memory>
 #include <cassert>
+#include "mpi.h"
+
+template <typename T>
+class MPIDataTypeResolver {
+public:
+    MPI_Datatype getMPIDatatype();
+};
 
 namespace xacc {
 
@@ -142,6 +149,49 @@ class ProcessGroup {
      different MPI processes, thus putting them into disjoint subgroups. **/
  std::shared_ptr<ProcessGroup> split(int my_subgroup) const;
 
+
+ // some useful wrappers
+
+ // I could move this to a single function, but don't
+ // want to abuse template specialization here
+ // this broadcasts a single element (int/char/double)
+ template<typename T>
+ void broadcast(T element) {
+
+  MPIDataTypeResolver<T> resolver;
+  MPI_Datatype mpiType = resolver.getMPIDatatype();
+  MPI_Bcast(&element, 1, mpiType, 0,
+              this->getMPICommProxy().getRef<MPI_Comm>());
+ }
+
+ // this broadcasts a vector
+ template<typename T>
+ void broadcast(std::vector<T> &vec) {
+
+  MPIDataTypeResolver<T> resolver;
+  MPI_Datatype mpiType = resolver.getMPIDatatype();
+  MPI_Bcast(vec.data(), vec.size(), mpiType, 0,
+              this->getMPICommProxy().getRef<MPI_Comm>());
+ };
+
+
+ // this Allgatherv's the content of local vectors
+ // into a global vector
+ template<typename T>
+ void allGatherv(std::vector<T> &local,
+     std::vector<T> &global,
+		 std::vector<int> &nLocalData,
+		 std::vector<int> &shift) {
+
+  MPIDataTypeResolver<T> resolver;
+  MPI_Datatype mpiType = resolver.getMPIDatatype();
+  MPI_Allgatherv(local.data(), local.size(), mpiType,
+	     global.data(), nLocalData.data(),
+	     shift.data(), mpiType,
+	     this->getMPICommProxy().getRef<MPI_Comm>());
+
+ }
+
 protected:
 
  std::vector<unsigned int> process_ranks_; //global ranks of the MPI processes forming the process group