(torchx/entrypoints) Use importlib.metadata instead of the backported importlib_metadata (#1087)

Summary:

torchx dropped support for python<=3.7 2 years ago (see: #728). But we kept using the backported `importlib_metadata` module to load configurations from `entry_points`.

Reviewed By: highker

Differential Revision: D77619564

Author: kiukchung

requirements.txt

@@ -1,6 +1,5 @@
 pyre-extensions
 docstring-parser>=0.8.1
-importlib-metadata
 pyyaml
 docker
 filelock

torchx/util/entrypoints.py

@@ -6,11 +6,10 @@
 
 # pyre-strict
 
+from importlib import metadata
+from importlib.metadata import EntryPoint
 from typing import Any, Dict, Optional
 
-import importlib_metadata as metadata
-from importlib_metadata import EntryPoint
-
 
 # pyre-ignore-all-errors[3, 2]
 def load(group: str, name: str, default=None):
@@ -30,13 +29,29 @@ def load(group: str, name: str, default=None):
     raises an error.
     """
 
-    entrypoints = metadata.entry_points().select(group=group)
+    # return type of importlib.metadata.entry_points() is different between python-3.9 and python-3.10
+    # https://docs.python.org/3.9/library/importlib.metadata.html#importlib.metadata.entry_points
+    # https://docs.python.org/3.10/library/importlib.metadata.html#importlib.metadata.entry_points
+    if hasattr(metadata.entry_points(), "select"):
+        # python>=3.10
+        entrypoints = metadata.entry_points().select(group=group)
 
-    if name not in entrypoints.names and default is not None:
-        return default
+        if name not in entrypoints.names and default is not None:
+            return default
 
-    ep = entrypoints[name]
-    return ep.load()
+        ep = entrypoints[name]
+        return ep.load()
+    else:
+        # python<3.10 (e.g. 3.9)
+        entrypoints = metadata.entry_points()[group]
+
+        # pyre-ignore[16] entrypoints is a Tuple[EntryPoint] in python-3.9
+        for ep in entrypoints:
+            if ep.name == name:
+                return ep.load()
+
+        # [group].name not found
+        return default
 
 
 def _defer_load_ep(ep: EntryPoint) -> object:

torchx/util/test/entrypoints_test.py

@@ -8,12 +8,12 @@
 
 import unittest
 from configparser import ConfigParser
+
+from importlib.metadata import EntryPoint, EntryPoints
 from types import ModuleType
 from typing import List
 from unittest.mock import MagicMock, patch
 
-from importlib_metadata import EntryPoint, EntryPoints
-
 from torchx.util.entrypoints import load, load_group