use time.time_ns() for better precision (#202)

Signed-off-by: Inada Naoki <[email protected]>

fluent/event.py

@@ -1,11 +1,12 @@
-import time
-
 from fluent import sender
 
 
 class Event:
     def __init__(self, label, data, **kwargs):
         assert isinstance(data, dict), "data must be a dict"
         sender_ = kwargs.get("sender", sender.get_global_sender())
-        timestamp = kwargs.get("time", int(time.time()))
-        sender_.emit_with_time(label, timestamp, data)
+        timestamp = kwargs.get("time", None)
+        if timestamp is not None:
+            sender_.emit_with_time(label, timestamp, data)
+        else:
+            sender_.emit(label, data)

fluent/sender.py

@@ -30,15 +30,21 @@ def close():  # pragma: no cover
 
 
 class EventTime(msgpack.ExtType):
-    def __new__(cls, timestamp):
+    def __new__(cls, timestamp, nanoseconds=None):
         seconds = int(timestamp)
-        nanoseconds = int(timestamp % 1 * 10**9)
+        if nanoseconds is None:
+            nanoseconds = int(timestamp % 1 * 10**9)
         return super().__new__(
             cls,
             code=0,
             data=struct.pack(">II", seconds, nanoseconds),
         )
 
+    @classmethod
+    def from_unix_nano(cls, unix_nano):
+        seconds, nanos = divmod(unix_nano, 10**9)
+        return cls(seconds, nanos)
+
 
 class FluentSender:
     def __init__(
@@ -78,7 +84,7 @@ def __init__(
 
     def emit(self, label, data):
         if self.nanosecond_precision:
-            cur_time = EventTime(time.time())
+            cur_time = EventTime.from_unix_nano(time.time_ns())
         else:
             cur_time = int(time.time())
         return self.emit_with_time(label, cur_time, data)
@@ -129,7 +135,7 @@ def close(self):
 
     def _make_packet(self, label, timestamp, data):
         if label:
-            tag = ".".join((self.tag, label)) if self.tag else label
+            tag = f"{self.tag}.{label}" if self.tag else label
         else:
             tag = self.tag
         if self.nanosecond_precision and isinstance(timestamp, float):