Copy async_lru for Python 3.7 compatibility

great_ai/external/async_lru.py

@@ -0,0 +1,192 @@
+import asyncio
+from collections import OrderedDict
+from functools import _CacheInfo, _make_key, partial, wraps
+
+__version__ = "1.0.3"
+
+__all__ = ("alru_cache",)
+
+
+def unpartial(fn):
+    while hasattr(fn, "func"):
+        fn = fn.func
+
+    return fn
+
+
+def _done_callback(fut, task):
+    if task.cancelled():
+        fut.cancel()
+        return
+
+    exc = task.exception()
+    if exc is not None:
+        fut.set_exception(exc)
+        return
+
+    fut.set_result(task.result())
+
+
+def _cache_invalidate(wrapped, typed, *args, **kwargs):
+    key = _make_key(args, kwargs, typed)
+
+    exists = key in wrapped._cache
+
+    if exists:
+        wrapped._cache.pop(key)
+
+    return exists
+
+
+def _cache_clear(wrapped):
+    wrapped.hits = wrapped.misses = 0
+    wrapped._cache = OrderedDict()
+    wrapped.tasks = set()
+
+
+def _open(wrapped):
+    if not wrapped.closed:
+        raise RuntimeError("alru_cache is not closed")
+
+    was_closed = (
+        wrapped.hits == wrapped.misses == len(wrapped.tasks) == len(wrapped._cache) == 0
+    )
+
+    if not was_closed:
+        raise RuntimeError("alru_cache was not closed correctly")
+
+    wrapped.closed = False
+
+
+def _close(wrapped, *, cancel=False, return_exceptions=True):
+    if wrapped.closed:
+        raise RuntimeError("alru_cache is closed")
+
+    wrapped.closed = True
+
+    if cancel:
+        for task in wrapped.tasks:
+            if not task.done():  # not sure is it possible
+                task.cancel()
+
+    return _wait_closed(wrapped, return_exceptions=return_exceptions)
+
+
+async def _wait_closed(wrapped, *, return_exceptions):
+    wait_closed = asyncio.gather(*wrapped.tasks, return_exceptions=return_exceptions)
+
+    wait_closed.add_done_callback(partial(_close_waited, wrapped))
+
+    ret = await wait_closed
+
+    # hack to get _close_waited callback to be executed
+    await asyncio.sleep(0)
+
+    return ret
+
+
+def _close_waited(wrapped, _):
+    wrapped.cache_clear()
+
+
+def _cache_info(wrapped, maxsize):
+    return _CacheInfo(
+        wrapped.hits,
+        wrapped.misses,
+        maxsize,
+        len(wrapped._cache),
+    )
+
+
+def __cache_touch(wrapped, key):
+    try:
+        wrapped._cache.move_to_end(key)
+    except KeyError:  # not sure is it possible
+        pass
+
+
+def _cache_hit(wrapped, key):
+    wrapped.hits += 1
+    __cache_touch(wrapped, key)
+
+
+def _cache_miss(wrapped, key):
+    wrapped.misses += 1
+    __cache_touch(wrapped, key)
+
+
+def alru_cache(
+    fn=None,
+    maxsize=128,
+    typed=False,
+    *,
+    cache_exceptions=True,
+):
+    def wrapper(fn):
+        _origin = unpartial(fn)
+
+        if not asyncio.iscoroutinefunction(_origin):
+            raise RuntimeError("Coroutine function is required, got {}".format(fn))
+
+        # functools.partialmethod support
+        if hasattr(fn, "_make_unbound_method"):
+            fn = fn._make_unbound_method()
+
+        @wraps(fn)
+        async def wrapped(*fn_args, **fn_kwargs):
+            if wrapped.closed:
+                raise RuntimeError("alru_cache is closed for {}".format(wrapped))
+
+            loop = asyncio.get_event_loop()
+
+            key = _make_key(fn_args, fn_kwargs, typed)
+
+            fut = wrapped._cache.get(key)
+
+            if fut is not None:
+                if not fut.done():
+                    _cache_hit(wrapped, key)
+                    return await asyncio.shield(fut)
+
+                exc = fut._exception
+
+                if exc is None or cache_exceptions:
+                    _cache_hit(wrapped, key)
+                    return fut.result()
+
+                # exception here and cache_exceptions == False
+                wrapped._cache.pop(key)
+
+            fut = loop.create_future()
+            task = loop.create_task(fn(*fn_args, **fn_kwargs))
+            task.add_done_callback(partial(_done_callback, fut))
+
+            wrapped.tasks.add(task)
+            task.add_done_callback(wrapped.tasks.remove)
+
+            wrapped._cache[key] = fut
+
+            if maxsize is not None and len(wrapped._cache) > maxsize:
+                wrapped._cache.popitem(last=False)
+
+            _cache_miss(wrapped, key)
+            return await asyncio.shield(fut)
+
+        _cache_clear(wrapped)
+        wrapped._origin = _origin
+        wrapped.closed = False
+        wrapped.cache_info = partial(_cache_info, wrapped, maxsize)
+        wrapped.cache_clear = partial(_cache_clear, wrapped)
+        wrapped.invalidate = partial(_cache_invalidate, wrapped, typed)
+        wrapped.close = partial(_close, wrapped)
+        wrapped.open = partial(_open, wrapped)
+
+        return wrapped
+
+    if fn is None:
+        return wrapper
+
+    if callable(fn) or hasattr(fn, "_make_unbound_method"):
+        return wrapper(fn)
+
+    raise NotImplementedError("{} decorating is not supported".format(fn))