BENCH: implement asvs for get_resolution

asv_bench/benchmarks/tslibs/resolution.py

@@ -0,0 +1,50 @@
+"""
+ipython analogue:
+
+tr = TimeResolution()
+mi = pd.MultiIndex.from_product(tr.params[:-1] + ([str(x) for x in tr.params[-1]],))
+df = pd.DataFrame(np.nan, index=mi, columns=["mean", "stdev"])
+
+for unit in tr.params[0]:
+    for size in tr.params[1]:
+        for tz in tr.params[2]:
+            tr.setup(unit, size, tz)
+            key = (unit, size, str(tz))
+            print(key)
+
+            val = %timeit -o tr.time_get_resolution(unit, size, tz)
+
+            df.loc[key] = (val.average, val.stdev)
+
+"""
+from datetime import timedelta, timezone
+
+from dateutil.tz import gettz, tzlocal
+import numpy as np
+import pytz
+
+from pandas._libs.tslibs.resolution import get_resolution
+
+
+class TimeResolution:
+    params = (
+        ["D", "h", "m", "s", "us", "ns"],
+        [1, 100, 10 ** 4, 10 ** 6],
+        [
+            None,
+            timezone.utc,
+            timezone(timedelta(minutes=60)),
+            pytz.timezone("US/Pacific"),
+            gettz("Asia/Tokyo"),
+            tzlocal(),
+        ],
+    )
+    param_names = ["unit", "size", "tz"]
+
+    def setup(self, unit, size, tz):
+        arr = np.random.randint(0, 10, size=size, dtype="i8")
+        arr = arr.view(f"M8[{unit}]").astype("M8[ns]").view("i8")
+        self.i8data = arr
+
+    def time_get_resolution(self, unit, size, tz):
+        get_resolution(self.i8data, tz)