Function TEST

tests/cpp/common/test_hist_util.cc:19–72

namespace xgboost::common {
TEST(ParallelGHistBuilder, Reset) {
  constexpr size_t kBins = 10;
  constexpr size_t kNodes = 5;
  constexpr size_t kNodesExtended = 10;
  constexpr size_t kTasksPerNode = 10;
  constexpr double kValue = 1.0;
  const size_t nthreads = AllThreadsForTest();

  HistCollection collection;
  collection.Init(kBins);

  for (size_t inode = 0; inode < kNodesExtended; inode++) {
    collection.AddHistRow(inode);
    collection.AllocateData(inode);
  }
  ParallelGHistBuilder hist_builder;
  hist_builder.Init(kBins);
  std::vector<GHistRow> target_hist(kNodes);
  for (size_t i = 0; i < target_hist.size(); ++i) {
    target_hist[i] = collection[i];
  }

  common::BlockedSpace2d space(kNodes, [&](size_t /* node*/) { return kTasksPerNode; }, 1);
  hist_builder.Reset(nthreads, kNodes, space, target_hist);

  common::ParallelFor2d(space, nthreads, [&](size_t inode, common::Range1d) {
    const size_t tid = omp_get_thread_num();

    GHistRow hist = hist_builder.GetInitializedHist(tid, inode);
    // fill hist by some non-null values
    for (size_t j = 0; j < kBins; ++j) {
      hist[j].Add(kValue, kValue);
    }
  });

  // reset and extend buffer
  target_hist.resize(kNodesExtended);
  for (size_t i = 0; i < target_hist.size(); ++i) {
    target_hist[i] = collection[i];
  }
  common::BlockedSpace2d space2(kNodesExtended, [&](size_t /*node*/) { return kTasksPerNode; }, 1);
  hist_builder.Reset(nthreads, kNodesExtended, space2, target_hist);

  common::ParallelFor2d(space2, nthreads, [&](size_t inode, common::Range1d) {
    const size_t tid = omp_get_thread_num();

    GHistRow hist = hist_builder.GetInitializedHist(tid, inode);
    // fill hist by some non-null values
    for (size_t j = 0; j < kBins; ++j) {
      ASSERT_EQ(0.0, hist[j].GetGrad());
      ASSERT_EQ(0.0, hist[j].GetHess());
    }
  });
}

TEST(ParallelGHistBuilder, ReduceHist) {
  constexpr size_t kBins = 10;