fix pk sampler's get_dataset error due to num_class unavaiable at pre-runtime

mindspore/ccsrc/minddata/dataset/engine/datasetops/source/sampler/pk_sampler.h

@@ -66,6 +66,11 @@ class PKSamplerRT : public SamplerRT {  // NOT YET FINISHED
   /// \return Status of the function
   Status to_json(nlohmann::json *out_json) override;
 
+  /// \brief PK cannot return an exact value because num_classes is not known until runtime, hence -1 is used
+  /// \param[out] num_rows
+  /// \return -1, which means PKSampler doesn't know how much data
+  int64_t CalculateNumSamples(int64_t num_rows) override { return -1; }
+
  private:
   bool shuffle_;
   uint32_t seed_;

mindspore/ccsrc/minddata/dataset/engine/datasetops/source/sampler/sampler.cc

@@ -140,6 +140,8 @@ int64_t SamplerRT::CalculateNumSamples(int64_t num_rows) {
   int64_t child_num_rows = num_rows;
   if (!child_.empty()) {
     child_num_rows = child_[0]->CalculateNumSamples(num_rows);
+    // return -1 if child_num_rows is undetermined
+    if (child_num_rows == -1) return child_num_rows;
   }
 
   return (num_samples_ > 0) ? std::min(child_num_rows, num_samples_) : child_num_rows;

mindspore/ccsrc/minddata/dataset/engine/datasetops/source/sampler/sampler.h

@@ -108,7 +108,7 @@ class SamplerRT {
 
   // Calculate num samples. Unlike GetNumSamples, it is not a getter and doesn't necessarily return the value of
   // num_samples_
-  // @return number of samples
+  // @return number of samples, return -1 if sampler cannot determine this value (e.g. PKSampler)
   virtual int64_t CalculateNumSamples(int64_t num_rows);
 
   // setter for num or records in the dataset

mindspore/ccsrc/minddata/dataset/engine/datasetops/source/sampler/sequential_sampler.cc

@@ -109,6 +109,8 @@ int64_t SequentialSamplerRT::CalculateNumSamples(int64_t num_rows) {
   int64_t child_num_rows = num_rows;
   if (!child_.empty()) {
     child_num_rows = child_[0]->CalculateNumSamples(num_rows);
+    // return -1 if child_num_rows is undetermined
+    if (child_num_rows == -1) return child_num_rows;
   }
   int64_t num_samples = (num_samples_ > 0) ? std::min(child_num_rows, num_samples_) : child_num_rows;
   // For this sampler we need to take start_index into account. Because for example in the case we are given n rows

mindspore/ccsrc/minddata/dataset/engine/datasetops/source/sampler/subset_sampler.cc

@@ -139,6 +139,8 @@ int64_t SubsetSamplerRT::CalculateNumSamples(int64_t num_rows) {
   int64_t child_num_rows = num_rows;
   if (!child_.empty()) {
     child_num_rows = child_[0]->CalculateNumSamples(num_rows);
+    // return -1 if child_num_rows is undetermined
+    if (child_num_rows == -1) return child_num_rows;
   }
   int64_t res = (num_samples_ > 0) ? std::min(child_num_rows, num_samples_) : child_num_rows;
   res = std::min(res, static_cast<int64_t>(indices_.size()));

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/source/celeba_node.cc

@@ -144,6 +144,9 @@ Status CelebANode::GetDatasetSize(const std::shared_ptr<DatasetSizeGetter> &size
   std::shared_ptr<SamplerRT> sampler_rt = nullptr;
   RETURN_IF_NOT_OK(sampler_->SamplerBuild(&sampler_rt));
   sample_size = sampler_rt->CalculateNumSamples(num_rows);
+  if (sample_size == -1) {
+    RETURN_IF_NOT_OK(size_getter->DryRun(shared_from_this(), &sample_size));
+  }
   *dataset_size = sample_size;
   return Status::OK();
 }

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/source/cifar100_node.cc

@@ -95,7 +95,9 @@ Status Cifar100Node::GetDatasetSize(const std::shared_ptr<DatasetSizeGetter> &si
   std::shared_ptr<SamplerRT> sampler_rt = nullptr;
   RETURN_IF_NOT_OK(sampler_->SamplerBuild(&sampler_rt));
   sample_size = sampler_rt->CalculateNumSamples(num_rows);
-
+  if (sample_size == -1) {
+    RETURN_IF_NOT_OK(size_getter->DryRun(shared_from_this(), &sample_size));
+  }
   *dataset_size = sample_size;
   dataset_size_ = *dataset_size;
   return Status::OK();

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/source/cifar10_node.cc

@@ -88,12 +88,17 @@ Status Cifar10Node::GetDatasetSize(const std::shared_ptr<DatasetSizeGetter> &siz
     *dataset_size = dataset_size_;
     return Status::OK();
   }
+
   int64_t num_rows, sample_size;
   RETURN_IF_NOT_OK(CifarOp::CountTotalRows(dataset_dir_, usage_, true, &num_rows));
   std::shared_ptr<SamplerRT> sampler_rt = nullptr;
   RETURN_IF_NOT_OK(sampler_->SamplerBuild(&sampler_rt));
   sample_size = sampler_rt->CalculateNumSamples(num_rows);
 
+  if (sample_size == -1) {
+    RETURN_IF_NOT_OK(size_getter->DryRun(shared_from_this(), &sample_size));
+  }
+
   *dataset_size = sample_size;
   dataset_size_ = *dataset_size;
   return Status::OK();

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/source/coco_node.cc

@@ -151,6 +151,9 @@ Status CocoNode::GetDatasetSize(const std::shared_ptr<DatasetSizeGetter> &size_g
   std::shared_ptr<SamplerRT> sampler_rt = nullptr;
   RETURN_IF_NOT_OK(sampler_->SamplerBuild(&sampler_rt));
   sample_size = sampler_rt->CalculateNumSamples(num_rows);
+  if (sample_size == -1) {
+    RETURN_IF_NOT_OK(size_getter->DryRun(shared_from_this(), &sample_size));
+  }
   *dataset_size = sample_size;
   dataset_size_ = *dataset_size;
   return Status::OK();

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/source/image_folder_node.cc

@@ -100,6 +100,9 @@ Status ImageFolderNode::GetDatasetSize(const std::shared_ptr<DatasetSizeGetter>
   std::shared_ptr<SamplerRT> sampler_rt = nullptr;
   RETURN_IF_NOT_OK(sampler_->SamplerBuild(&sampler_rt));
   sample_size = sampler_rt->CalculateNumSamples(num_rows);
+  if (sample_size == -1) {
+    RETURN_IF_NOT_OK(size_getter->DryRun(shared_from_this(), &sample_size));
+  }
   *dataset_size = sample_size;
   dataset_size_ = *dataset_size;
   return Status::OK();

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/source/manifest_node.cc

@@ -123,6 +123,9 @@ Status ManifestNode::GetDatasetSize(const std::shared_ptr<DatasetSizeGetter> &si
   std::shared_ptr<SamplerRT> sampler_rt = nullptr;
   RETURN_IF_NOT_OK(sampler_->SamplerBuild(&sampler_rt));
   sample_size = sampler_rt->CalculateNumSamples(num_rows);
+  if (sample_size == -1) {
+    RETURN_IF_NOT_OK(size_getter->DryRun(shared_from_this(), &sample_size));
+  }
   *dataset_size = sample_size;
   dataset_size_ = *dataset_size;
   return Status::OK();

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/source/mnist_node.cc

@@ -88,6 +88,9 @@ Status MnistNode::GetDatasetSize(const std::shared_ptr<DatasetSizeGetter> &size_
   std::shared_ptr<SamplerRT> sampler_rt = nullptr;
   RETURN_IF_NOT_OK(sampler_->SamplerBuild(&sampler_rt));
   sample_size = sampler_rt->CalculateNumSamples(num_rows);
+  if (sample_size == -1) {
+    RETURN_IF_NOT_OK(size_getter->DryRun(shared_from_this(), &sample_size));
+  }
   *dataset_size = sample_size;
   dataset_size_ = *dataset_size;
   return Status::OK();

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/source/voc_node.cc

@@ -139,6 +139,9 @@ Status VOCNode::GetDatasetSize(const std::shared_ptr<DatasetSizeGetter> &size_ge
   std::shared_ptr<SamplerRT> sampler_rt = nullptr;
   RETURN_IF_NOT_OK(sampler_->SamplerBuild(&sampler_rt));
   sample_size = sampler_rt->CalculateNumSamples(num_rows);
+  if (sample_size == -1) {
+    RETURN_IF_NOT_OK(size_getter->DryRun(shared_from_this(), &sample_size));
+  }
   *dataset_size = sample_size;
   dataset_size_ = *dataset_size;
   return Status::OK();

tests/ut/cpp/dataset/ir_sampler_test.cc

@@ -36,7 +36,7 @@ TEST_F(MindDataTestIrSampler, TestCalculateNumSamples) {
   sampl = std::make_shared<PKSamplerObj>(3, false, 0);
   EXPECT_NE(sampl, nullptr);
   sampl->SamplerBuild(&sampler_rt);
-  EXPECT_EQ(sampler_rt->CalculateNumSamples(num_rows), 30);
+  EXPECT_EQ(sampler_rt->CalculateNumSamples(num_rows), -1);
 
   sampl = std::make_shared<RandomSamplerObj>(false, 12);
   EXPECT_NE(sampl, nullptr);
@@ -98,7 +98,7 @@ TEST_F(MindDataTestIrSampler, TestCalculateNumSamples) {
   std::shared_ptr<SamplerRT> sampler_rt6;
   sampl6->SamplerBuild(&sampler_rt6);
   sampler_rt6->AddChild(sampler_rt5);
-  EXPECT_EQ(sampler_rt6->CalculateNumSamples(num_rows), 7);
+  EXPECT_EQ(sampler_rt6->CalculateNumSamples(num_rows), -1);
 }
 
 TEST_F(MindDataTestIrSampler, TestSamplersMoveParameters) {

tests/ut/python/dataset/test_datasets_cifarop.py

@@ -501,6 +501,35 @@ def test_cifar_exception_file_path():
         assert "map operation: [PyFunc] failed. The corresponding data files" in str(e)
 
 
+def test_cifar10_pk_sampler_get_dataset_size():
+    """
+    Test Cifar10Dataset with PKSampler and get_dataset_size
+    """
+    sampler = ds.PKSampler(3)
+    data = ds.Cifar10Dataset(DATA_DIR_10, sampler=sampler)
+    num_iter = 0
+    ds_sz = data.get_dataset_size()
+    for _ in data.create_dict_iterator(num_epochs=1, output_numpy=True):
+        num_iter += 1
+
+    assert ds_sz == num_iter == 30
+
+
+def test_cifar10_with_chained_sampler_get_dataset_size():
+    """
+    Test Cifar10Dataset with PKSampler chained with a SequentialSampler and get_dataset_size
+    """
+    sampler = ds.SequentialSampler(start_index=0, num_samples=5)
+    child_sampler = ds.PKSampler(4)
+    sampler.add_child(child_sampler)
+    data = ds.Cifar10Dataset(DATA_DIR_10, sampler=sampler)
+    num_iter = 0
+    ds_sz = data.get_dataset_size()
+    for _ in data.create_dict_iterator(num_epochs=1, output_numpy=True):
+        num_iter += 1
+    assert ds_sz == num_iter == 5
+
+
 if __name__ == '__main__':
     test_cifar10_content_check()
     test_cifar10_basic()
@@ -517,3 +546,6 @@ if __name__ == '__main__':
 
     test_cifar_usage()
     test_cifar_exception_file_path()
+
+    test_cifar10_with_chained_sampler_get_dataset_size()
+    test_cifar10_pk_sampler_get_dataset_size()