Support host data in proxy DMatrix. (#7087)

tests/cpp/data/test_adapter.cc

@@ -1,4 +1,4 @@
-// Copyright (c) 2019 by Contributors
+// Copyright (c) 2019-2021 by XGBoost Contributors
 #include <gtest/gtest.h>
 #include <type_traits>
 #include <utility>
@@ -35,6 +35,27 @@ TEST(Adapter, CSRAdapter) {
   EXPECT_EQ(line2.GetElement(0).column_idx, 1);
 }
 
+TEST(Adapter, CSRArrayAdapter) {
+  HostDeviceVector<bst_row_t> indptr;
+  HostDeviceVector<float> values;
+  HostDeviceVector<bst_feature_t> indices;
+  size_t n_features = 100, n_samples = 10;
+  RandomDataGenerator{n_samples, n_features, 0.5}.GenerateCSR(&values, &indptr, &indices);
+  auto indptr_arr = MakeArrayInterface(indptr.HostPointer(), indptr.Size());
+  auto values_arr = MakeArrayInterface(values.HostPointer(), values.Size());
+  auto indices_arr = MakeArrayInterface(indices.HostPointer(), indices.Size());
+  auto adapter = data::CSRArrayAdapter(
+      StringView{indptr_arr.c_str(), indptr_arr.size()},
+      StringView{values_arr.c_str(), values_arr.size()},
+      StringView{indices_arr.c_str(), indices_arr.size()}, n_features);
+  auto batch = adapter.Value();
+  ASSERT_EQ(batch.NumRows(), n_samples);
+  ASSERT_EQ(batch.NumCols(), n_features);
+
+  ASSERT_EQ(adapter.NumRows(), n_samples);
+  ASSERT_EQ(adapter.NumColumns(), n_features);
+}
+
 TEST(Adapter, CSCAdapterColsMoreThanRows) {
   std::vector<float> data = {1, 2, 3, 4, 5, 6, 7, 8};
   std::vector<unsigned> row_idx = {0, 1, 0, 1, 0, 1, 0, 1};

tests/cpp/data/test_proxy_dmatrix.cc

@@ -0,0 +1,31 @@
+/*!
+ * Copyright 2021 XGBoost contributors
+ */
+#include <gtest/gtest.h>
+#include "../helpers.h"
+#include "../../../src/data/proxy_dmatrix.h"
+#include "../../../src/data/adapter.h"
+
+namespace xgboost {
+namespace data {
+TEST(ProxyDMatrix, HostData) {
+  DMatrixProxy proxy;
+  size_t constexpr kRows = 100, kCols = 10;
+  std::vector<HostDeviceVector<float>> label_storage(1);
+
+  HostDeviceVector<float> storage;
+  auto data = RandomDataGenerator(kRows, kCols, 0.5)
+                  .Device(0)
+                  .GenerateArrayInterface(&storage);
+
+  proxy.SetArrayData(data.c_str());
+
+  auto n_samples = HostAdapterDispatch(
+      &proxy, [](auto const &value) { return value.Size(); });
+  ASSERT_EQ(n_samples, kRows);
+  auto n_features = HostAdapterDispatch(
+      &proxy, [](auto const &value) { return value.NumCols(); });
+  ASSERT_EQ(n_features, kCols);
+}
+}  // namespace data
+}  // namespace xgboost

tests/cpp/data/test_proxy_dmatrix.cu

@@ -7,7 +7,7 @@
 
 namespace xgboost {
 namespace data {
-TEST(ProxyDMatrix, Basic) {
+TEST(ProxyDMatrix, DeviceData) {
   constexpr size_t kRows{100}, kCols{100};
   HostDeviceVector<float> storage;
   auto data = RandomDataGenerator(kRows, kCols, 0.5)