Reading bp files using stepping mode BeginStep EndStep

Modifying file names

source/adios2/engine/bp/BPFileReader.cpp

@@ -25,6 +25,43 @@ BPFileReader::BPFileReader(IO &io, const std::string &name, const Mode mode,
     Init();
 }
 
+StepStatus BPFileReader::BeginStep(StepMode mode, const float timeoutSeconds)
+{
+    if (m_DebugMode && mode != StepMode::NextAvailable)
+    {
+        throw std::invalid_argument("ERROR: mode is not supported yet for "
+                                    "engine BPFileReader, in call to "
+                                    "BeginStep\n");
+    }
+
+    const auto &variablesData = m_IO.GetVariablesDataMap();
+
+    for (const auto &variableData : variablesData)
+    {
+        const std::string name = variableData.first;
+        const std::string type = m_IO.InquireVariableType(name);
+
+        if (type == "compound")
+        {
+        }
+#define declare_type(T)                                                        \
+    else if (type == GetType<T>())                                             \
+    {                                                                          \
+        auto variable = m_IO.InquireVariable<T>(name);                         \
+        if (mode == StepMode::NextAvailable)                                   \
+        {                                                                      \
+            variable->SetStepSelection({m_CurrentStep + 1, 1});                \
+        }                                                                      \
+    }
+        ADIOS2_FOREACH_TYPE_1ARG(declare_type)
+#undef declare_type
+    }
+
+    return StepStatus::OK;
+}
+
+void BPFileReader::EndStep() { ++m_CurrentStep; }
+
 void BPFileReader::PerformGets()
 {
     const std::map<std::string, SubFileInfoMap> variablesSubfileInfo =

source/adios2/engine/bp/BPFileReader.h

@@ -42,6 +42,11 @@ public:
 
     virtual ~BPFileReader() = default;
 
+    StepStatus BeginStep(StepMode mode = StepMode::NextAvailable,
+                         const float timeoutSeconds = 0.f) final;
+
+    void EndStep() final;
+
     void PerformGets() final;
 
     void Close(const int transportIndex = -1);
@@ -51,6 +56,9 @@ private:
     transportman::TransportMan m_FileManager;
     transportman::TransportMan m_SubFileManager;
 
+    /** updates if step=1 in EndStep function, used for per-step reads */
+    size_t m_CurrentStep = 0;
+
     void Init();
     void InitTransports();
     void InitBuffer();

testing/adios2/engine/SmallTestData.h

@@ -64,4 +64,19 @@ SmallTestData generateNewSmallTestData(SmallTestData in, int step, int rank,
     return in;
 }
 
+void UpdateSmallTestData(SmallTestData &in, int step, int rank, int size)
+{
+    int j = rank + 1 + step * size;
+    std::for_each(in.I8.begin(), in.I8.end(), [&](int8_t &v) { v += j; });
+    std::for_each(in.I16.begin(), in.I16.end(), [&](int16_t &v) { v += j; });
+    std::for_each(in.I32.begin(), in.I32.end(), [&](int32_t &v) { v += j; });
+    std::for_each(in.I64.begin(), in.I64.end(), [&](int64_t &v) { v += j; });
+    std::for_each(in.U8.begin(), in.U8.end(), [&](uint8_t &v) { v += j; });
+    std::for_each(in.U16.begin(), in.U16.end(), [&](uint16_t &v) { v += j; });
+    std::for_each(in.U32.begin(), in.U32.end(), [&](uint32_t &v) { v += j; });
+    std::for_each(in.U64.begin(), in.U64.end(), [&](uint64_t &v) { v += j; });
+    std::for_each(in.R32.begin(), in.R32.end(), [&](float &v) { v += j; });
+    std::for_each(in.R64.begin(), in.R64.end(), [&](double &v) { v += j; });
+}
+
 #endif // TESTING_ADIOS2_ENGINE_SMALLTESTDATA_H_

testing/adios2/engine/bp/CMakeLists.txt

@@ -6,18 +6,23 @@
 add_executable(TestBPWriteReadADIOS2 TestBPWriteReadADIOS2.cpp)
 target_link_libraries(TestBPWriteReadADIOS2 adios2 gtest gtest_main)
 
+add_executable(TestBPWriteReadAsStreamADIOS2 TestBPWriteReadAsStreamADIOS2.cpp)
+target_link_libraries(TestBPWriteReadAsStreamADIOS2 adios2 gtest gtest_main)
+
 add_executable(TestBPWriteReadAttributesADIOS2 TestBPWriteReadAttributesADIOS2.cpp)
 target_link_libraries(TestBPWriteReadAttributesADIOS2 adios2 gtest gtest_main)
 
 
 if(ADIOS2_HAVE_MPI)
   target_link_libraries(TestBPWriteReadADIOS2 MPI::MPI_C)
+  target_link_libraries(TestBPWriteReadAsStreamADIOS2 MPI::MPI_C)
   target_link_libraries(TestBPWriteReadAttributesADIOS2 MPI::MPI_C)
   
   set(extra_test_args EXEC_WRAPPER ${MPIEXEC_COMMAND})
 endif()
 
 gtest_add_tests(TARGET TestBPWriteReadADIOS2 ${extra_test_args})
+gtest_add_tests(TARGET TestBPWriteReadAsStreamADIOS2 ${extra_test_args})
 gtest_add_tests(TARGET TestBPWriteReadAttributesADIOS2 ${extra_test_args})
   
 if (ADIOS2_HAVE_ADIOS1)