Move collective file reading to a common header

include/picongpu/plugins/common/MPIHelpers.cpp

@@ -0,0 +1,86 @@
+/* Copyright 2021 Franz Poeschel
+ *
+ * This file is part of PIConGPU.
+ *
+ * PIConGPU is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PIConGPU is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with PIConGPU.
+ * If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "picongpu/plugins/common/MPIHelpers.hpp"
+
+#include <pmacc/communication/manager_common.hpp>
+
+#include <algorithm>
+#include <fstream>
+#include <numeric>
+#include <sstream>
+#include <vector>
+
+
+namespace picongpu
+{
+    /**
+     * @brief Read a file in MPI-collective manner.
+     *
+     * The file is read on rank 0 and its contents subsequently distributed
+     * to all other ranks.
+     *
+     * @param path Path for the file to read.
+     * @param comm MPI communicator.
+     * @return std::string Full file content.
+     */
+    std::string collective_file_read(std::string const& path, MPI_Comm comm)
+    {
+        int rank, size;
+        MPI_CHECK(MPI_Comm_rank(comm, &rank));
+        MPI_CHECK(MPI_Comm_size(comm, &size));
+
+        std::string res;
+        size_t stringLength = 0;
+        if(rank == 0)
+        {
+            std::fstream handle;
+            handle.open(path, std::ios_base::in);
+            std::stringstream stream;
+            stream << handle.rdbuf();
+            res = stream.str();
+            if(!handle.good())
+            {
+                throw std::runtime_error("Failed reading JSON config from file " + path + ".");
+            }
+            stringLength = res.size() + 1;
+        }
+        MPI_Datatype datatype = MPI_Types<size_t>{}.value;
+        int err = MPI_Bcast(&stringLength, 1, datatype, 0, comm);
+        if(err != MPI_SUCCESS)
+        {
+            throw std::runtime_error("[collective_file_read] MPI_Bcast stringLength failure.");
+        }
+        std::vector<char> recvbuf(stringLength, 0);
+        if(rank == 0)
+        {
+            std::copy_n(res.c_str(), stringLength, recvbuf.data());
+        }
+        err = MPI_Bcast(recvbuf.data(), stringLength, MPI_CHAR, 0, comm);
+        if(err != MPI_SUCCESS)
+        {
+            throw std::runtime_error("[collective_file_read] MPI_Bcast file content failure.");
+        }
+        if(rank != 0)
+        {
+            res = recvbuf.data();
+        }
+        return res;
+    }
+} // namespace picongpu

include/picongpu/plugins/common/MPIHelpers.hpp

@@ -0,0 +1,66 @@
+/* Copyright 2021 Franz Poeschel
+ *
+ * This file is part of PIConGPU.
+ *
+ * PIConGPU is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PIConGPU is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with PIConGPU.
+ * If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <vector>
+
+#include <mpi.h>
+
+namespace picongpu
+{
+    /**
+     * @brief Helper class to help figure out a platform-independent
+     *        MPI_Datatype for size_t.
+     */
+    template<typename>
+    struct MPI_Types;
+
+    template<>
+    struct MPI_Types<unsigned long>
+    {
+        // can't make this constexpr due to MPI
+        // so, make this non-static for simplicity
+        MPI_Datatype value = MPI_UNSIGNED_LONG;
+    };
+
+    template<>
+    struct MPI_Types<unsigned long long>
+    {
+        MPI_Datatype value = MPI_UNSIGNED_LONG_LONG;
+    };
+
+    template<>
+    struct MPI_Types<unsigned>
+    {
+        MPI_Datatype value = MPI_UNSIGNED;
+    };
+
+    /**
+     * @brief Read a file in MPI-collective manner.
+     *
+     * The file is read on rank 0 and its contents subsequently distributed
+     * to all other ranks.
+     *
+     * @param path Path for the file to read.
+     * @param comm MPI communicator.
+     * @return std::string Full file content.
+     */
+    std::string collective_file_read(std::string const& path, MPI_Comm comm);
+} // namespace picongpu

include/picongpu/plugins/openPMD/Json.cpp

@@ -25,8 +25,6 @@
 
 #    include <algorithm> // std::copy_n, std::find
 #    include <cctype> // std::isspace
-#    include <fstream>
-#    include <sstream>
 
 /*
  * Note:
@@ -225,60 +223,6 @@ namespace
         }
     }
 
-    /**
-     * @brief Read a file in MPI-collective manner.
-     *
-     * The file is read on rank 0 and its contents subsequently distributed
-     * to all other ranks.
-     *
-     * @param path Path for the file to read.
-     * @param comm MPI communicator.
-     * @return std::string Full file content.
-     */
-    std::string collective_file_read(std::string const& path, MPI_Comm comm)
-    {
-        int rank, size;
-        MPI_Comm_rank(comm, &rank);
-        MPI_Comm_size(comm, &size);
-
-        std::string res;
-        size_t stringLength = 0;
-        if(rank == 0)
-        {
-            std::fstream handle;
-            handle.open(path, std::ios_base::in);
-            std::stringstream stream;
-            stream << handle.rdbuf();
-            res = stream.str();
-            if(!handle.good())
-            {
-                throw std::runtime_error("Failed reading JSON config from file " + path + ".");
-            }
-            stringLength = res.size() + 1;
-        }
-        MPI_Datatype datatype = MPI_Types<size_t>{}.value;
-        int err = MPI_Bcast(&stringLength, 1, datatype, 0, comm);
-        if(err)
-        {
-            throw std::runtime_error("[collective_file_read] MPI_Bcast stringLength failure.");
-        }
-        std::vector<char> recvbuf(stringLength, 0);
-        if(rank == 0)
-        {
-            std::copy_n(res.c_str(), stringLength, recvbuf.data());
-        }
-        err = MPI_Bcast(recvbuf.data(), stringLength, MPI_CHAR, 0, comm);
-        if(err)
-        {
-            throw std::runtime_error("[collective_file_read] MPI_Bcast file content failure.");
-        }
-        if(rank != 0)
-        {
-            res = recvbuf.data();
-        }
-        return res;
-    }
-
     KindOfConfig readPattern(
         std::vector<picongpu::json::Pattern>& patterns,
         nlohmann::json& defaultConfig,

include/picongpu/plugins/openPMD/Json_private.hpp

@@ -19,13 +19,13 @@
 
 #pragma once
 
+#include "picongpu/plugins/common/MPIHelpers.hpp"
 #include "picongpu/plugins/openPMD/Json.hpp"
 
 #include <regex>
 #include <string>
 #include <vector>
 
-#include <mpi.h>
 #include <nlohmann/json.hpp>
 
 /*
@@ -208,45 +208,6 @@ namespace
      */
     std::string extractFilename(std::string const& unparsed);
 
-    /**
-     * @brief Helper class to help figure out a platform-independent
-     *        MPI_Datatype for size_t.
-     */
-    template<typename>
-    struct MPI_Types;
-
-    template<>
-    struct MPI_Types<unsigned long>
-    {
-        // can't make this constexpr due to MPI
-        // so, make this non-static for simplicity
-        MPI_Datatype value = MPI_UNSIGNED_LONG;
-    };
-
-    template<>
-    struct MPI_Types<unsigned long long>
-    {
-        MPI_Datatype value = MPI_UNSIGNED_LONG_LONG;
-    };
-
-    template<>
-    struct MPI_Types<unsigned>
-    {
-        MPI_Datatype value = MPI_UNSIGNED;
-    };
-
-    /**
-     * @brief Read a file in MPI-collective manner.
-     *
-     * The file is read on rank 0 and its contents subsequently distributed
-     * to all other ranks.
-     *
-     * @param path Path for the file to read.
-     * @param comm MPI communicator.
-     * @return std::string Full file content.
-     */
-    std::string collective_file_read(std::string const& path, MPI_Comm comm);
-
     enum class KindOfConfig : char
     {
         Pattern,