[io] add unit test infrastructure for streaming large objects

Uses RStreamerField as a test bed for (de-)serializing large objects
with TBufferFile.

Author: jblomer

tree/ntuple/test/CMakeLists.txt

@@ -114,6 +114,13 @@ ROOT_GENERATE_DICTIONARY(StreamerFieldDict ${CMAKE_CURRENT_SOURCE_DIR}/StreamerF
                          MODULE rfield_streamer LINKDEF StreamerFieldLinkDef.h OPTIONS -inlineInputHeader
                          DEPENDENCIES RIO)
 
+if (CMAKE_SIZEOF_VOID_P EQUAL 8)
+   ROOT_ADD_GTEST(rfield_streamer_beyond rfield_streamer_beyond.cxx StreamerBeyond.cxx LIBRARIES ROOTNTuple)
+   ROOT_GENERATE_DICTIONARY(StreamerBeyondDict ${CMAKE_CURRENT_SOURCE_DIR}/StreamerBeyond.hxx
+                           MODULE rfield_streamer_beyond LINKDEF StreamerBeyondLinkDef.h OPTIONS -inlineInputHeader
+                           DEPENDENCIES RIO)
+endif()
+
 if(MSVC)
   set(command ${CMAKE_COMMAND} -E env "ROOTIGNOREPREFIX=1" $<TARGET_FILE:genreflex>)
 else()

tree/ntuple/test/StreamerBeyond.cxx

@@ -0,0 +1 @@
+#include "StreamerBeyond.hxx"

tree/ntuple/test/StreamerBeyond.hxx

@@ -0,0 +1,14 @@
+#ifndef ROOT_RNTuple_Test_StreamerBeyond
+#define ROOT_RNTuple_Test_StreamerBeyond
+
+#include <Rtypes.h>
+
+#include <cstdint>
+#include <vector>
+
+struct StreamerBeyond {
+   std::vector<std::int64_t> fOne;
+   std::vector<std::int64_t> fTwo;
+};
+
+#endif

tree/ntuple/test/StreamerBeyondLinkDef.h

@@ -0,0 +1,5 @@
+#ifdef __CLING__
+
+#pragma link C++ options=rntupleStreamerMode(true) struct StreamerBeyond+;
+
+#endif

tree/ntuple/test/rfield_streamer_beyond.cxx

@@ -0,0 +1,46 @@
+#include <ROOT/RFieldBase.hxx>
+#include <ROOT/RNTupleModel.hxx>
+#include <ROOT/RNTupleReader.hxx>
+#include <ROOT/RNTupleWriter.hxx>
+
+#include <ROOT/TestSupport.hxx>
+
+#include <cstdio>
+#include <string>
+#include <utility>
+
+#include "StreamerBeyond.hxx"
+#include "gtest/gtest.h"
+
+TEST(RField, StreamerBeyond)
+{
+   ROOT::TestSupport::FileRaii fileGuard("test_ntuple_rfield_streamer_beyond.root");
+
+   {
+      auto model = ROOT::RNTupleModel::Create();
+      auto f = ROOT::RFieldBase::Create("f", "StreamerBeyond").Unwrap();
+      EXPECT_TRUE(dynamic_cast<ROOT::RStreamerField *>(f.get()));
+      model->AddField(std::move(f));
+      auto writer = ROOT::RNTupleWriter::Recreate(std::move(model), "ntpl", fileGuard.GetPath());
+
+      auto ptr = writer->GetModel().GetDefaultEntry().GetPtr<StreamerBeyond>("f");
+      ptr->fOne = std::vector<std::int64_t>(100000000, -1);
+      ptr->fTwo = std::vector<std::int64_t>(100000000, -2);
+
+      writer->Fill();
+   }
+
+   auto reader = ROOT::RNTupleReader::Open("ntpl", fileGuard.GetPath());
+   ASSERT_EQ(1u, reader->GetNEntries());
+   StreamerBeyond sb;
+   auto view = reader->GetView("f", &sb, "StreamerBeyond");
+
+   view(0);
+
+   auto ptr = view.GetValue().GetPtr<StreamerBeyond>();
+   EXPECT_EQ(100000000u, ptr->fOne.size());
+   EXPECT_EQ(-1, ptr->fOne.at(1000));
+   EXPECT_EQ(100000000u, ptr->fTwo.size());
+   EXPECT_EQ(-2, ptr->fTwo.at(2000));
+   EXPECT_EQ(-2, ptr->fTwo.at(99999999u));
+}