one more round of version tagging

nomenklatura/versions.py

@@ -5,13 +5,15 @@
 from typing import Any, List, Iterator, Optional
 from datetime import datetime, timezone
 
-ALPHABET = string.digits + string.ascii_lowercase
+ALPHABET = string.ascii_lowercase
 
 
 class Version(object):
     """A class to represent a dataset version, which consists of a timestamp
     and a string tag."""
 
+    __slots__ = ["dt", "tag"]
+
     def __init__(self, dt: datetime, tag: str) -> None:
         self.dt: datetime = dt
         self.tag: str = tag
@@ -23,9 +25,11 @@ def new(cls, tag: Optional[str] = None) -> "Version":
 
         if tag is None:
             # This keeps the tag sortable but short.
-            tag_num = ((now.microsecond // 1000) * 10) + random.randint(0, 9)
-            tag = cls._tag_encode(int(tag_num))
+            tag_num = (now.microsecond // 1000) * 10
+            tag_num_ = tag_num + random.randint(0, 9)
+            tag = cls._tag_encode(int(tag_num_))
 
+        tag = tag.ljust(3, "x")[:3]
         now = now.replace(microsecond=0)
         return cls(now, tag)
 

tests/test_versions.py

@@ -1,9 +1,10 @@
 import os
 import pytest
+from typing import Optional
 from nomenklatura.versions import Version, VersionHistory
 
 
-def test_version():
+def test_version() -> None:
     runid = Version.new("aaa")
     assert runid.id.startswith(runid.dt.strftime("%Y%m%d%H%M%S"))
     assert len(runid.tag) == 3
@@ -24,6 +25,13 @@ def test_version():
     runid4 = Version.from_env("NK_RUN2222_ID")
     assert runid4.id != runid2.id
 
+    prev_id: Optional[Version] = None
+    for i in range(100):
+        next_id = Version.new()
+        if prev_id is not None:
+            assert next_id.dt >= prev_id.dt, (next_id, prev_id)
+        prev_id = next_id
+
 
 def test_run_history():
     original = VersionHistory([])