Fix merging of stream datasets (openvinotoolkit#1609)

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https://github.com/openvinotoolkit/datumaro/blob/develop/CONTRIBUTING.md
-->

When importing a stream dataset with multiple sources in eager mode by
specifying `error_policy` or `progress_reporting`, an error occurs:
```
'_MergedStreamDataset' object has no attribute '_data'
```

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Resolves openvinotoolkit#111 and openvinotoolkit#222.
Depends on openvinotoolkit#1000 (for series of dependent commits).

This PR introduces this capability to make the project better in this
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- Added this feature
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- Fixed the problem openvinotoolkit#1234
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- [x] I have added integration tests to cover my changes.​
- [x] I have added the description of my changes into
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```python
```

---------

Signed-off-by: dependabot[bot] <[email protected]>
Signed-off-by: Ilya Trushkin <[email protected]>
Co-authored-by: williamcorsel <[email protected]>
Co-authored-by: Sooah Lee <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Yunchu Lee <[email protected]>
Co-authored-by: Wonju Lee <[email protected]>

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   (<https://github.com/openvinotoolkit/datumaro/pull/1607>)
 
 ### Bug fixes
+- Fix StreamDataset merging when importing in eager mode
+  (<https://github.com/openvinotoolkit/datumaro/pull/1609>)
 
 ## Q3 2024 Release 1.9.0
 ### New features

src/datumaro/components/dataset.py

@@ -1023,17 +1023,22 @@ class _MergedStreamDataset(cls):
                 def __init__(self, *sources: IDataset):
                     from datumaro.components.hl_ops import HLOps
 
-                    self.merged = HLOps.merge(*sources, merge_policy=merge_policy)
+                    self._merged = HLOps.merge(*sources, merge_policy=merge_policy)
+                    self._data = self._merged._data
+                    self._env = env
+                    self._format = DEFAULT_FORMAT
+                    self._source_path = None
+                    self._options = {}
 
                 def __iter__(self):
-                    yield from self.merged
+                    yield from self._merged
 
                 @property
                 def is_stream(self):
                     return True
 
                 def subsets(self) -> Dict[str, DatasetSubset]:
-                    return self.merged.subsets()
+                    return self._merged.subsets()
 
             return _MergedStreamDataset(*sources)
 

tests/unit/test_imagenet_format.py

@@ -7,6 +7,7 @@
 import pytest
 
 from datumaro.components.annotation import AnnotationType, Label, LabelCategories
+from datumaro.components.contexts.importer import ImportErrorPolicy
 from datumaro.components.dataset import Dataset, StreamDataset
 from datumaro.components.dataset_base import DatasetItem
 from datumaro.components.environment import Environment
@@ -214,7 +215,9 @@ def _create_expected_dataset(self):
     @pytest.mark.parametrize("dataset_cls, is_stream", [(Dataset, False), (StreamDataset, True)])
     def test_can_import(self, dataset_cls, is_stream, helper_tc):
         expected_dataset = self._create_expected_dataset()
-        dataset = dataset_cls.import_from(self.DUMMY_DATASET_DIR, self.IMPORTER_NAME)
+        dataset = dataset_cls.import_from(
+            self.DUMMY_DATASET_DIR, self.IMPORTER_NAME, error_policy=ImportErrorPolicy()
+        )
         assert dataset.is_stream == is_stream
 
         compare_datasets(helper_tc, expected_dataset, dataset, require_media=True)
@@ -240,7 +243,9 @@ class ImagenetWithSubsetDirsImporterTest(ImagenetImporterTest):
     @mark_requirement(Requirements.DATUM_GENERAL_REQ)
     @pytest.mark.parametrize("dataset_cls, is_stream", [(Dataset, False), (StreamDataset, True)])
     def test_can_import(self, dataset_cls, is_stream, helper_tc):
-        dataset = dataset_cls.import_from(self.DUMMY_DATASET_DIR, self.IMPORTER_NAME)
+        dataset = dataset_cls.import_from(
+            self.DUMMY_DATASET_DIR, self.IMPORTER_NAME, error_policy=ImportErrorPolicy()
+        )
         assert dataset.is_stream == is_stream
 
         for subset_name, subset in dataset.subsets().items():