Copy async_lru for Python 3.7 compatibility

tests/external/test_partialmethod.py

@@ -0,0 +1,50 @@
+import asyncio
+from functools import partial, partialmethod
+
+import pytest
+from great_ai.external.async_lru import alru_cache
+
+pytestmark = pytest.mark.asyncio
+
+
+async def test_partialmethod_basic(check_lru, loop):
+    class Obj:
+        async def _coro(self, val):
+            return val
+
+        coro = alru_cache(partialmethod(_coro, 2))
+
+    obj = Obj()
+
+    coros = [obj.coro() for _ in range(5)]
+
+    check_lru(obj.coro, hits=0, misses=0, cache=0, tasks=0)
+
+    ret = await asyncio.gather(*coros)
+
+    check_lru(obj.coro, hits=4, misses=1, cache=1, tasks=0)
+
+    assert ret == [2, 2, 2, 2, 2]
+
+
+async def test_partialmethod_partial(check_lru, loop):
+    class Obj:
+        def __init__(self):
+            self.coro = alru_cache(partial(self._coro, 2))
+
+        async def __coro(self, val1, val2):
+            return val1 + val2
+
+        _coro = partialmethod(__coro, 1)
+
+    obj = Obj()
+
+    coros = [obj.coro() for _ in range(5)]
+
+    check_lru(obj.coro, hits=0, misses=0, cache=0, tasks=0)
+
+    ret = await asyncio.gather(*coros)
+
+    check_lru(obj.coro, hits=4, misses=1, cache=1, tasks=0)
+
+    assert ret == [3, 3, 3, 3, 3]