rewrite: New Scheduled Session System.

src/modules/schedule/lib.py

@@ -0,0 +1,41 @@
+import asyncio
+import itertools
+import datetime as dt
+
+from utils.ratelimits import Bucket
+
+
+def time_to_slotid(time: dt.datetime) -> int:
+    """
+    Return the slotid for the provided time.
+    """
+    utctime = time.astimezone(dt.timezone.utc)
+    hour = utctime.replace(minute=0, second=0, microsecond=0)
+    return int(hour.timestamp())
+
+
+def slotid_to_utc(sessionid: int) -> dt.datetime:
+    """
+    Convert the given slotid (hour EPOCH) into a utc datetime.
+    """
+    return dt.datetime.fromtimestamp(sessionid, tz=dt.timezone.utc)
+
+
+async def batchrun_per_second(awaitables, batchsize):
+    """
+    Run provided awaitables concurrently,
+    ensuring that no more than `batchsize` are running at once,
+    and that no more than `batchsize` are spawned per second.
+
+    Returns list of returned results or exceptions.
+    """
+    bucket = Bucket(batchsize, 1)
+    sem = asyncio.Semaphore(batchsize)
+
+    tasks = []
+    for awaitable in awaitables:
+        await asyncio.gather(bucket.wait(), sem.acquire())
+        bucket.request()
+        task = asyncio.create_task(awaitable)
+        task.add_done_callback(lambda fut: sem.release())
+    return await asyncio.gather(*tasks, return_exceptions=True)