Add graph function to list DataPipes from graph

test/test_graph.py

@@ -13,7 +13,7 @@
 from _utils._common_utils_for_test import IS_WINDOWS
 from torch.utils.data import IterDataPipe
 from torchdata.dataloader2 import DataLoader2, MultiProcessingReadingService, ReadingServiceInterface
-from torchdata.dataloader2.graph import find_dps, remove_dp, replace_dp, traverse_dps
+from torchdata.dataloader2.graph import find_dps, list_dps, remove_dp, replace_dp, traverse_dps
 from torchdata.datapipes.iter import IterableWrapper, Mapper
 from torchdata.datapipes.utils import to_graph
 
@@ -97,6 +97,44 @@ def test_find_dps(self) -> None:
         for dp in dps:
             self.assertTrue(dp in expected_dps)
 
+    def test_list_dps(self) -> None:
+        def _validate_fn(dps, exp_dps):
+            self.assertEqual(len(dps), len(exp_dps))
+            exp_set = {*exp_dps}
+            for dp in dps:
+                self.assertTrue(dp in exp_set)
+
+        graph, exp_all_dps = self._get_datapipes()
+        (
+            src_dp,
+            m1,
+            ub,
+            dm,
+            c1,
+            c2,
+            m2,
+            dp,
+        ) = exp_all_dps
+
+        # List all DataPipes
+        dps = list_dps(graph)
+        _validate_fn(dps, exp_all_dps)
+
+        # List all DataPipes excluding a single DataPipe
+        dps = list_dps(graph, exclude_dps=m1)
+        _, _, *exp_dps = exp_all_dps
+        _validate_fn(dps, exp_dps)
+
+        dps = list_dps(graph, exclude_dps=m2)
+        *exp_dps_1, _, c2, _, dp = exp_all_dps
+        exp_dps = list(exp_dps_1) + [c2, dp]
+        _validate_fn(dps, exp_dps)
+
+        # List all DataPipes excluding multiple DataPipes
+        dps = list_dps(graph, exclude_dps=[m1, m2])
+        exp_dps = [ub, dm, c2, dp]
+        _validate_fn(dps, exp_dps)
+
     def _validate_graph(self, graph, nested_dp):
         self.assertEqual(len(graph), len(nested_dp))
         for dp_id, sub_nested_dp in zip(graph, nested_dp):

torchdata/dataloader2/graph/__init__.py

@@ -0,0 +1,24 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+
+from torch.utils.data.graph import DataPipe, DataPipeGraph, traverse_dps
+
+from torchdata.dataloader2.graph.utils import find_dps, list_dps, remove_dp, replace_dp
+
+
+__all__ = [
+    "DataPipe",
+    "DataPipeGraph",
+    "find_dps",
+    "list_dps",
+    "remove_dp",
+    "replace_dp",
+    "traverse_dps",
+]
+
+
+assert __all__ == sorted(__all__)

torchdata/dataloader2/graph.py → torchdata/dataloader2/graph/utils.py

@@ -5,17 +5,13 @@
 # LICENSE file in the root directory of this source tree.
 
 
-from typing import List, Type
-
-from torch.utils.data.graph import DataPipe, DataPipeGraph, traverse_dps
+from typing import List, Optional, Set, Type, Union
 
+from torchdata.dataloader2.graph import DataPipe, DataPipeGraph, traverse_dps
 from torchdata.datapipes.iter import IterDataPipe
 from torchdata.datapipes.map import MapDataPipe
 
 
-__all__ = ["find_dps", "replace_dp", "remove_dp"]
-
-
 def find_dps(graph: DataPipeGraph, dp_type: Type[DataPipe]) -> List[DataPipe]:
     r"""
     Given the graph of DataPipe generated by ``traverse_dps`` function, return DataPipe
@@ -34,6 +30,33 @@ def helper(g) -> None:  # pyre-ignore
     return dps
 
 
+def list_dps(graph: DataPipeGraph, exclude_dps: Optional[Union[DataPipe, List[DataPipe]]] = None) -> List[DataPipe]:
+    r"""
+    Given the graph of DataPipe generated by ``traverse_dps`` function,
+    return DataPipe instances excluding the provided DataPipe and its prior DataPipe graph.
+    """
+    dps: List[DataPipe] = []
+    cache: Set[int] = set()
+
+    if exclude_dps is not None:
+        if isinstance(exclude_dps, (IterDataPipe, MapDataPipe)):
+            cache.add(id(exclude_dps))
+        else:
+            for dp in exclude_dps:  # type: ignore[union-attr]
+                cache.add(id(dp))
+
+    def helper(g) -> None:  # pyre-ignore
+        for dp_id, (dp, src_graph) in g.items():
+            if dp_id not in cache:
+                cache.add(dp_id)
+                dps.append(dp)
+                helper(src_graph)
+
+    helper(graph)
+
+    return dps
+
+
 # Given the DataPipe needs to be replaced and the expected DataPipe, return a new graph
 def replace_dp(graph: DataPipeGraph, old_datapipe: DataPipe, new_datapipe: DataPipe) -> DataPipeGraph:
     r"""