[python-package] [dask] add type annotations on dask._HostWorkers (#5766)

python-package/lightgbm/dask.py

@@ -7,7 +7,7 @@ dask.Array and dask.DataFrame collections.
 It is based on dask-lightgbm, which was based on dask-xgboost.
 """
 import socket
-from collections import defaultdict, namedtuple
+from collections import defaultdict
 from copy import deepcopy
 from enum import Enum, auto
 from functools import partial
@@ -37,7 +37,18 @@ _DaskVectorLike = Union[dask_Array, dask_Series]
 _DaskPart = Union[np.ndarray, pd_DataFrame, pd_Series, ss.spmatrix]
 _PredictionDtype = Union[Type[np.float32], Type[np.float64], Type[np.int32], Type[np.int64]]
 
-_HostWorkers = namedtuple('_HostWorkers', ['default', 'all'])
+
+class _HostWorkers:
+
+    def __init__(self, default: str, all_workers: List[str]):
+        self.default = default
+        self.all_workers = all_workers
+
+    def __eq__(self, other: "_HostWorkers") -> bool:
+        return (
+            self.default == other.default
+            and self.all_workers == other.all_workers
+        )
 
 
 class _DatasetNames(Enum):
@@ -105,9 +116,9 @@ def _group_workers_by_host(worker_addresses: Iterable[str]) -> Dict[str, _HostWo
         if not hostname:
             raise ValueError(f"Could not parse host name from worker address '{address}'")
         if hostname not in host_to_workers:
-            host_to_workers[hostname] = _HostWorkers(default=address, all=[address])
+            host_to_workers[hostname] = _HostWorkers(default=address, all_workers=[address])
         else:
-            host_to_workers[hostname].all.append(address)
+            host_to_workers[hostname].all_workers.append(address)
     return host_to_workers
 
 
@@ -124,7 +135,7 @@ def _assign_open_ports_to_workers(
     """
     host_ports_futures = {}
     for hostname, workers in host_to_workers.items():
-        n_workers_in_host = len(workers.all)
+        n_workers_in_host = len(workers.all_workers)
         host_ports_futures[hostname] = client.submit(
             _find_n_open_ports,
             n=n_workers_in_host,
@@ -135,7 +146,7 @@ def _assign_open_ports_to_workers(
     found_ports = client.gather(host_ports_futures)
     worker_to_port = {}
     for hostname, workers in host_to_workers.items():
-        for worker, port in zip(workers.all, found_ports[hostname]):
+        for worker, port in zip(workers.all_workers, found_ports[hostname]):
             worker_to_port[worker] = port
     return worker_to_port
 

tests/python_package_test/test_dask.py

@@ -525,7 +525,7 @@ def test_group_workers_by_host():
     expected = {
         host: lgb.dask._HostWorkers(
             default=f'tcp://{host}:0',
-            all=[f'tcp://{host}:0', f'tcp://{host}:1']
+            all_workers=[f'tcp://{host}:0', f'tcp://{host}:1']
         )
         for host in hosts
     }