tests/cpp: Add tests for SparsePageDMatrix

The SparsePageDMatrix or external memory DMatrix reads data from the
file IO rather than load it into RAM.

tests/cpp/data/test_sparse_page_dmatrix.cc

@@ -0,0 +1,98 @@
+// Copyright by Contributors
+#include <xgboost/data.h>
+#include "../../../src/data/sparse_page_dmatrix.h"
+
+#include "../helpers.h"
+
+TEST(SparsePageDMatrix, MetaInfo) {
+  std::string tmp_file = CreateSimpleTestData();
+  xgboost::DMatrix * dmat = xgboost::DMatrix::Load(
+    tmp_file + "#" + tmp_file + ".cache", true, false);
+  std::remove(tmp_file.c_str());
+  EXPECT_TRUE(FileExists(tmp_file + ".cache"));
+
+  // Test the metadata that was parsed
+  EXPECT_EQ(dmat->info().num_row, 2);
+  EXPECT_EQ(dmat->info().num_col, 5);
+  EXPECT_EQ(dmat->info().num_nonzero, 6);
+  EXPECT_EQ(dmat->info().labels.size(), dmat->info().num_row);
+
+  // Clean up of external memory files
+  std::remove((tmp_file + ".cache").c_str());
+  std::remove((tmp_file + ".cache.row.page").c_str());
+}
+
+TEST(SparsePageDMatrix, RowAccess) {
+  std::string tmp_file = CreateSimpleTestData();
+  xgboost::DMatrix * dmat = xgboost::DMatrix::Load(
+    tmp_file + "#" + tmp_file + ".cache", true, false);
+  std::remove(tmp_file.c_str());
+  EXPECT_TRUE(FileExists(tmp_file + ".cache.row.page"));
+
+  dmlc::DataIter<xgboost::RowBatch> * row_iter = dmat->RowIterator();
+  // Loop over the batches and count the records
+  long row_count = 0;
+  row_iter->BeforeFirst();
+  while (row_iter->Next()) row_count += row_iter->Value().size;
+  EXPECT_EQ(row_count, dmat->info().num_row);
+  // Test the data read into the first row
+  row_iter->BeforeFirst();
+  row_iter->Next();
+  xgboost::SparseBatch::Inst first_row = row_iter->Value()[0];
+  ASSERT_EQ(first_row.length, 3);
+  EXPECT_EQ(first_row[2].index, 2);
+  EXPECT_EQ(first_row[2].fvalue, 20);
+  row_iter = nullptr;
+
+  // Clean up of external memory files
+  std::remove((tmp_file + ".cache").c_str());
+  std::remove((tmp_file + ".cache.row.page").c_str());
+}
+
+TEST(SparsePageDMatrix, ColAcess) {
+  std::string tmp_file = CreateSimpleTestData();
+  xgboost::DMatrix * dmat = xgboost::DMatrix::Load(
+    tmp_file + "#" + tmp_file + ".cache", true, false);
+  std::remove(tmp_file.c_str());
+  EXPECT_FALSE(FileExists(tmp_file + ".cache.col.page"));
+
+  EXPECT_EQ(dmat->HaveColAccess(), false);
+  const std::vector<bool> enable(dmat->info().num_col, true);
+  dmat->InitColAccess(enable, 1, 1); // Max 1 row per patch
+  ASSERT_EQ(dmat->HaveColAccess(), true);
+  EXPECT_TRUE(FileExists(tmp_file + ".cache.col.page"));
+
+  EXPECT_EQ(dmat->GetColSize(0), 2);
+  EXPECT_EQ(dmat->GetColSize(1), 1);
+  EXPECT_EQ(dmat->GetColDensity(0), 1);
+  EXPECT_EQ(dmat->GetColDensity(1), 0.5);
+
+  dmlc::DataIter<xgboost::ColBatch> * col_iter = dmat->ColIterator();
+  // Loop over the batches and assert the data is as expected
+  long num_col_batch = 0;
+  col_iter->BeforeFirst();
+  while (col_iter->Next()) {
+    num_col_batch += 1;
+    EXPECT_EQ(col_iter->Value().size, dmat->info().num_col)
+      << "Expected batch size to be same as num_cols as max_row_perbatch is 1.";
+  }
+  EXPECT_EQ(num_col_batch, dmat->info().num_row)
+    << "Expected num batches to be same as num_rows as max_row_perbatch is 1";
+  col_iter = nullptr;
+
+  std::vector<xgboost::bst_uint> sub_feats = {4, 3};
+  dmlc::DataIter<xgboost::ColBatch> * sub_col_iter = dmat->ColIterator(sub_feats);
+  // Loop over the batches and assert the data is as expected
+  sub_col_iter->BeforeFirst();
+  while (sub_col_iter->Next()) {
+    EXPECT_EQ(sub_col_iter->Value().size, sub_feats.size())
+      << "Expected size of a batch to be same as number of columns "
+      << "as max_row_perbatch was set to 1.";
+  }
+  sub_col_iter = nullptr;
+
+  // Clean up of external memory files
+  std::remove((tmp_file + ".cache").c_str());
+  std::remove((tmp_file + ".cache.col.page").c_str());
+  std::remove((tmp_file + ".cache.row.page").c_str());
+}

tests/cpp/helpers.cc

@@ -4,6 +4,11 @@ std::string TempFileName() {
   return std::tmpnam(nullptr);
 }
 
+bool FileExists(const std::string name) {
+  struct stat st;
+  return stat(name.c_str(), &st) == 0; 
+}
+
 long GetFileSize(const std::string filename) {
   struct stat st;
   stat(filename.c_str(), &st);

tests/cpp/helpers.h

@@ -12,6 +12,8 @@
 
 std::string TempFileName();
 
+bool FileExists(const std::string name);
+
 long GetFileSize(const std::string filename);
 
 std::string CreateSimpleTestData();