add tai64n module;

Author: kristate

tai64n.py

@@ -0,0 +1,38 @@
+"""
+TAI64N encoding and decoding.
+TAI64N encodes nanosecond-accuracy timestamps and is supported by logstash.
+@see: U{http://cr.yp.to/libtai/tai64.html}.
+"""
+
+from __future__ import unicode_literals
+
+import struct
+
+_STRUCTURE = b">QI"
+_OFFSET = (2**62) + 10  # last 10 are leap seconds
+
+
+def encode(timestamp):
+    """
+    Convert seconds since epoch to TAI64N string.
+    @param timestamp: Seconds since UTC Unix epoch as C{float}.
+    @return: TAI64N-encoded time, as C{unicode}.
+    """
+    seconds = int(timestamp)
+    nanoseconds = int((timestamp - seconds) * 1000000000)
+    seconds = seconds + _OFFSET
+    return struct.pack(_STRUCTURE, seconds, nanoseconds)
+
+
+def decode(tai64n):
+    """
+    Convert TAI64N string to seconds since epoch.
+    Note that dates before 2013 may not decode accurately due to leap second
+    issues. If you need correct decoding for earlier dates you can try the
+    tai64n package available from PyPI (U{https://pypi.python.org/pypi/tai64n}).
+    @param tai64n: TAI64N-encoded time, as C{unicode}.
+    @return: Seconds since UTC Unix epoch as C{float}.
+    """
+    seconds, nanoseconds = struct.unpack(_STRUCTURE, tai64n)
+    seconds -= _OFFSET
+    return seconds + (nanoseconds / 1000000000.0)