fix: avoid timestamp rounding across precision boundaries

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Bug Fixes
 
+1. Avoid floating-point timestamp rounding across microsecond, millisecond, and second boundaries.
+
 1. [#706](https://github.com/influxdata/influxdb-client-python/pull/706): Use logger instead logging.
 1. [#710](https://github.com/influxdata/influxdb-client-python/pull/710): Stop `default_tags` from one client leaking into other clients' `WriteApi` (shared mutable default `PointSettings`).
 1. [#713](https://github.com/influxdata/influxdb-client-python/pull/713): Replace invalid tuple type annotations `(str, str, str)` with `Tuple[str, str, str]` in batching callbacks, examples and docs.

influxdb_client/client/write/point.py

@@ -351,11 +351,16 @@ def _convert_timestamp(timestamp, precision=DEFAULT_WRITE_PRECISION):
         if precision is None or precision == WritePrecision.NS:
             return ns
         elif precision == WritePrecision.US:
-            return ns / 1e3
+            divisor = 1000
         elif precision == WritePrecision.MS:
-            return ns / 1e6
+            divisor = 1000000
         elif precision == WritePrecision.S:
-            return ns / 1e9
+            divisor = 1000000000
+        else:
+            raise ValueError(timestamp)
+
+        # Keep truncation toward zero without rounding through a float.
+        return ns // divisor if ns >= 0 else -(-ns // divisor)
 
     raise ValueError(timestamp)
 

tests/test_PointTimestampBoundaries.py

@@ -0,0 +1,31 @@
+"""Timestamp boundary regressions through the public Point API."""
+
+import pandas as pd
+import pytest
+
+from influxdb_client import Point, WritePrecision
+from influxdb_client.client.util import date_utils
+from influxdb_client.client.util.date_utils_pandas import PandasDateTimeHelper
+
+
+@pytest.mark.parametrize("precision, divisor", [
+    (WritePrecision.US, 1000),
+    (WritePrecision.MS, 1000000),
+    (WritePrecision.S, 1000000000),
+])
+@pytest.mark.parametrize("sign", [1, -1])
+@pytest.mark.parametrize("on_boundary", [False, True])
+def test_point_timestamp_boundary(monkeypatch, precision, divisor, sign, on_boundary):
+    monkeypatch.setattr(date_utils, "date_helper", PandasDateTimeHelper())
+    magnitude = 1700000000000000000 + divisor - (0 if on_boundary else 1)
+    stamp = pd.Timestamp(sign * magnitude, unit="ns", tz="UTC")
+    point = Point("sensor").field("value", 1).time(stamp, precision)
+    assert point.to_line_protocol() == f"sensor value=1i {sign * (magnitude // divisor)}"
+
+
+@pytest.mark.parametrize("sign", [1, -1])
+def test_point_nanosecond_timestamp_unchanged(monkeypatch, sign):
+    monkeypatch.setattr(date_utils, "date_helper", PandasDateTimeHelper())
+    ns = sign * 1700000000000000999
+    point = Point("sensor").field("value", 1).time(pd.Timestamp(ns, unit="ns", tz="UTC"))
+    assert point.to_line_protocol() == f"sensor value=1i {ns}"