[Typing][C-20] Add type annotations for `python/paddle/distributed/co…

…mmunication/reduce.py` (PaddlePaddle#66803)

python/paddle/distributed/communication/reduce.py

@@ -12,10 +12,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, ClassVar, Literal
+
 import paddle
 from paddle import framework
 from paddle.distributed.communication import stream
 
+if TYPE_CHECKING:
+    from typing_extensions import TypeAlias
+
+    from paddle import Tensor
+    from paddle.base.core import task
+    from paddle.distributed.communication.group import Group
+
+    _ReduceOp: TypeAlias = Literal[0, 1, 2, 3, 4]
+
 
 class ReduceOp:
     """
@@ -48,11 +61,11 @@ class ReduceOp:
             >>> # [[5, 7, 9], [5, 7, 9]] (2 GPUs)
     """
 
-    SUM = 0
-    MAX = 1
-    MIN = 2
-    PROD = 3
-    AVG = 4
+    SUM: ClassVar[Literal[0]] = 0
+    MAX: ClassVar[Literal[1]] = 1
+    MIN: ClassVar[Literal[2]] = 2
+    PROD: ClassVar[Literal[3]] = 3
+    AVG: ClassVar[Literal[4]] = 4
 
 
 def _get_reduce_op(reduce_op, func_name):
@@ -86,7 +99,13 @@ def _to_inplace_op(op_name):
     return f"{op_name}_"
 
 
-def reduce(tensor, dst, op=ReduceOp.SUM, group=None, sync_op=True):
+def reduce(
+    tensor: Tensor,
+    dst: int,
+    op: _ReduceOp = ReduceOp.SUM,
+    group: Group | None = None,
+    sync_op: bool = True,
+) -> task:
     """
 
     Reduce a tensor to the destination from all others. As shown below, one process is started with a GPU and the data of this process is represented
@@ -103,7 +122,7 @@ def reduce(tensor, dst, op=ReduceOp.SUM, group=None, sync_op=True):
             should be float16, float32, float64, int32, int64, int8, uint8, bool or bfloat16.
         dst (int): The destination rank id.
         op (ReduceOp.SUM|ReduceOp.MAX|ReduceOp.MIN|ReduceOp.PROD|ReduceOp.AVG, optional): The operation used. Default value is ReduceOp.SUM.
-        group (Group, optional): The group instance return by new_group or None for global default group.
+        group (Group|None, optional): The group instance return by new_group or None for global default group.
         sync_op (bool, optional): Whether this op is a sync op. The default value is True.
 
     Returns:
@@ -207,7 +226,7 @@ def reduce(tensor, dst, op=ReduceOp.SUM, group=None, sync_op=True):
         raise ValueError(f"Unknown parameter: {op}.")
 
 
-def is_avg_reduce_op_supported():
+def is_avg_reduce_op_supported() -> bool:
     if paddle.is_compiled_with_cuda():
         return paddle.base.core.nccl_version() >= 21000
     else: