add x-ray interop

py_zipkin/util.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 import random
 import struct
+import time
 
 
 def generate_random_64bit_string():
@@ -17,9 +18,15 @@ def generate_random_128bit_string():
     """Returns a 128 bit UTF-8 encoded string. Follows the same conventions
     as generate_random_64bit_string().
 
-    :returns: random 32-character string
+    The upper 32 bits are the current time in epoch seconds, and the
+    lower 96 bits are random. This allows for AWS X-Ray `interop
+    <https://github.com/openzipkin/zipkin/issues/1754>`_
+
+    :returns: 32-character hex string
     """
-    return '{:032x}'.format(random.getrandbits(128))
+    t = int(time.time())
+    lower_96 = random.getrandbits(96)
+    return '{:032x}'.format((t << 96) | lower_96)
 
 
 def unsigned_hex_to_signed_int(hex_string):

tests/util_test.py

@@ -15,11 +15,14 @@ def test_generate_random_64bit_string(rand):
     assert isinstance(random_string, str)
 
 
+@mock.patch('py_zipkin.util.time.time', autospec=True)
 @mock.patch('py_zipkin.util.random.getrandbits', autospec=True)
-def test_generate_random_128bit_string(rand):
-    rand.return_value = 0x17133d482ba4f60517133d482ba4f605
+def test_generate_random_128bit_string(rand, mock_time):
+    rand.return_value = 0x2ba4f60517133d482ba4f605
+    mock_time.return_value = float(0x17133d48)
     random_string = util.generate_random_128bit_string()
     assert random_string == '17133d482ba4f60517133d482ba4f605'
+    rand.assert_called_once_with(96)  # 96 bits
     # This acts as a contract test of sorts. This should return a str
     # in both py2 and py3. IOW, no unicode objects.
     assert isinstance(random_string, str)