Implement iterative DMatrix. (#5837)

tests/cpp/helpers.cu

@@ -1,17 +1,43 @@
+#include <xgboost/c_api.h>
+
 #include "helpers.h"
 #include "../../src/data/device_adapter.cuh"
-#include "../../src/data/device_dmatrix.h"
+#include "../../src/data/iterative_device_dmatrix.h"
 
 namespace xgboost {
+
+CudaArrayIterForTest::CudaArrayIterForTest(float sparsity, size_t rows,
+                                           size_t cols, size_t batches)
+    : rows_{rows}, cols_{cols}, n_batches_{batches} {
+  XGProxyDMatrixCreate(&proxy_);
+  rng_.reset(new RandomDataGenerator{rows_, cols_, sparsity});
+  rng_->Device(0);
+  std::tie(batches_, interface_) =
+      rng_->GenerateArrayInterfaceBatch(&data_, n_batches_);
+  this->Reset();
+}
+
+CudaArrayIterForTest::~CudaArrayIterForTest() { XGDMatrixFree(proxy_); }
+
+int CudaArrayIterForTest::Next() {
+  if (iter_ == n_batches_) {
+    return 0;
+  }
+  XGDeviceQuantileDMatrixSetDataCudaArrayInterface(proxy_, batches_[iter_].c_str());
+  iter_++;
+  return 1;
+}
+
+size_t constexpr CudaArrayIterForTest::kRows;
+size_t constexpr CudaArrayIterForTest::kCols;
+
 std::shared_ptr<DMatrix> RandomDataGenerator::GenerateDeviceDMatrix(bool with_label,
                                                                     bool float_label,
                                                                     size_t classes) {
-  std::vector<HostDeviceVector<float>> storage(cols_);
-  std::string arr = this->GenerateColumnarArrayInterface(&storage);
-  auto adapter = data::CudfAdapter(arr);
-  std::shared_ptr<DMatrix> m {
-    new data::DeviceDMatrix{&adapter,
-          std::numeric_limits<float>::quiet_NaN(), 1, 256}};
+  CudaArrayIterForTest iter{this->sparsity_, this->rows_, this->cols_, 1};
+  auto m = std::make_shared<data::IterativeDeviceDMatrix>(
+      &iter, iter.Proxy(), Reset, Next, std::numeric_limits<float>::quiet_NaN(),
+      0, bins_);
   return m;
 }
 }  // namespace xgboost