SNOW-90646: Make TIMESTAMP_TZ result pickle-able.

Author: sfc-gh-stakeda

converter.py

@@ -6,7 +6,7 @@
 import binascii
 import decimal
 import time
-from datetime import datetime, timedelta, tzinfo, date
+from datetime import datetime, timedelta, date
 from logging import getLogger
 
 import pytz
@@ -34,9 +34,6 @@
 ZERO_EPOCH = datetime.utcfromtimestamp(0)
 ZERO_FILL = u'000000000'
 
-# Tzinfo class cache
-_TZINFO_CLASS_CACHE = {}
-
 logger = getLogger(__name__)
 
 PYTHON_TO_SNOWFLAKE_TYPE = {
@@ -132,31 +129,7 @@ def _generate_tzinfo_from_tzoffset(tzoffset_minutes):
     """
     Generates tzinfo object from tzoffset.
     """
-    try:
-        return _TZINFO_CLASS_CACHE[tzoffset_minutes]
-    except KeyError:
-        pass
-    sign = u'P' if tzoffset_minutes >= 0 else u'N'
-    abs_tzoffset_minutes = abs(tzoffset_minutes)
-    hour, minute = divmod(abs_tzoffset_minutes, 60)
-    name = u'GMT{sign:s}{hour:02d}{minute:02d}'.format(
-        sign=sign,
-        hour=hour,
-        minute=minute)
-    tzinfo_class_type = type(
-        str(name),  # str() for both Python 2 and 3
-        (tzinfo,),
-        dict(
-            utcoffset=lambda self0, dt, is_dst=False: timedelta(
-                minutes=tzoffset_minutes),
-            tzname=lambda self0, dt: name,
-            dst=lambda self0, dt: ZERO_TIMEDELTA,
-            __repr__=lambda _: name
-        )
-    )
-    tzinfo_cls = tzinfo_class_type()
-    _TZINFO_CLASS_CACHE[tzoffset_minutes] = tzinfo_cls
-    return tzinfo_cls
+    return pytz.FixedOffset(tzoffset_minutes)
 
 
 class SnowflakeConverter(object):

test/test_converter.py

@@ -18,7 +18,7 @@
 
 def _compose_tz(dt, tzinfo):
     ret = ZERO_EPOCH + timedelta(seconds=float(dt))
-    ret += tzinfo.utcoffset(ret, is_dst=False)
+    ret += tzinfo.utcoffset(ret)
     return ret.replace(tzinfo=tzinfo)
 
 
@@ -28,7 +28,7 @@ def _compose_ntz(dt):
 
 def _compose_ltz(dt, tz):
     ret = ZERO_EPOCH + timedelta(seconds=float(dt))
-    return pytz.utc.localize(ret, is_dst=False).astimezone(
+    return pytz.utc.localize(ret).astimezone(
         pytz.timezone(tz))
 
 

test/test_pickle_timestamp_tz.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2012-2019 Snowflake Computing Inc. All right reserved.
+#
+import os
+import pickle
+
+
+def test_pickle_timestamp_tz(tmpdir, conn_cnx):
+    """
+    Ensure the timestamp_tz result is pickle-able.
+    """
+    tmp_dir = str(tmpdir.mkdir('pickles'))
+    output = os.path.join(tmp_dir, 'tz.pickle')
+    expected_tz = None
+    with conn_cnx() as con:
+        for rec in con.cursor().execute("select '2019-08-11 01:02:03.123 -03:00'::TIMESTAMP_TZ"):
+            expected_tz = rec[0]
+            with open(output, 'wb') as f:
+                pickle.dump(expected_tz, f)
+
+    with open(output, 'rb') as f:
+        read_tz = pickle.load(f)
+        assert expected_tz == read_tz