more usage of array interface, fix potential memory leaks of std::str…

…ing (#9824)

R-package/src/xgboost_R.cc

@@ -59,6 +59,32 @@ namespace {
   return "";
 }
 
+[[nodiscard]] std::string MakeArrayInterfaceFromRVector(SEXP R_vec) {
+  const size_t vec_len = Rf_xlength(R_vec);
+
+  // Lambda for type dispatch.
+  auto make_vec = [=](auto const *ptr) {
+    using namespace xgboost;  // NOLINT
+    auto v = linalg::MakeVec(ptr, vec_len);
+    return linalg::ArrayInterfaceStr(v);
+  };
+
+  const SEXPTYPE arr_type = TYPEOF(R_vec);
+  switch (arr_type) {
+    case REALSXP:
+      return make_vec(REAL(R_vec));
+    case INTSXP:
+      return make_vec(INTEGER(R_vec));
+    case LGLSXP:
+      return make_vec(LOGICAL(R_vec));
+    default:
+      LOG(FATAL) << "Array or matrix has unsupported type.";
+  }
+
+  LOG(FATAL) << "Not reachable";
+  return "";
+}
+
 [[nodiscard]] std::string MakeJsonConfigForArray(SEXP missing, SEXP n_threads, SEXPTYPE arr_type) {
   using namespace ::xgboost;  // NOLINT
   Json jconfig{Object{}};
@@ -159,12 +185,15 @@ XGB_DLL SEXP XGDMatrixCreateFromMat_R(SEXP mat, SEXP missing, SEXP n_threads) {
   SEXP ret = PROTECT(R_MakeExternalPtr(nullptr, R_NilValue, R_NilValue));
   R_API_BEGIN();
 
-  auto array_str = MakeArrayInterfaceFromRMat(mat);
-  auto config_str = MakeJsonConfigForArray(missing, n_threads, TYPEOF(mat));
-
   DMatrixHandle handle;
-  CHECK_CALL(XGDMatrixCreateFromDense(array_str.c_str(), config_str.c_str(), &handle));
+  int res_code;
+  {
+    auto array_str = MakeArrayInterfaceFromRMat(mat);
+    auto config_str = MakeJsonConfigForArray(missing, n_threads, TYPEOF(mat));
 
+    res_code = XGDMatrixCreateFromDense(array_str.c_str(), config_str.c_str(), &handle);
+  }
+  CHECK_CALL(res_code);
   R_SetExternalPtrAddr(ret, handle);
   R_RegisterCFinalizerEx(ret, _DMatrixFinalizer, TRUE);
   R_API_END();
@@ -279,23 +308,15 @@ XGB_DLL SEXP XGDMatrixSaveBinary_R(SEXP handle, SEXP fname, SEXP silent) {
 
 XGB_DLL SEXP XGDMatrixSetInfo_R(SEXP handle, SEXP field, SEXP array) {
   R_API_BEGIN();
-  int len = length(array);
-  const char *name = CHAR(asChar(field));
-  auto ctx = DMatrixCtx(R_ExternalPtrAddr(handle));
-  if (!strcmp("group", name)) {
-    std::vector<unsigned> vec(len);
-    xgboost::common::ParallelFor(len, ctx->Threads(), [&](xgboost::omp_ulong i) {
-      vec[i] = static_cast<unsigned>(INTEGER(array)[i]);
-    });
-    CHECK_CALL(
-        XGDMatrixSetUIntInfo(R_ExternalPtrAddr(handle), CHAR(asChar(field)), BeginPtr(vec), len));
-  } else {
-    std::vector<float> vec(len);
-    xgboost::common::ParallelFor(len, ctx->Threads(),
-                                 [&](xgboost::omp_ulong i) { vec[i] = REAL(array)[i]; });
-    CHECK_CALL(
-        XGDMatrixSetFloatInfo(R_ExternalPtrAddr(handle), CHAR(asChar(field)), BeginPtr(vec), len));
+  SEXP field_ = PROTECT(Rf_asChar(field));
+  int res_code;
+  {
+    const std::string array_str = MakeArrayInterfaceFromRVector(array);
+    res_code = XGDMatrixSetInfoFromInterface(
+      R_ExternalPtrAddr(handle), CHAR(field_), array_str.c_str());
   }
+  CHECK_CALL(res_code);
+  UNPROTECT(1);
   R_API_END();
   return R_NilValue;
 }