Pad on the LS side

Author: ocelotl

lightstep/b3_propagator.py

@@ -65,9 +65,10 @@ def inject(self, span_context, carrier):
         carrier.update(baggage)
 
         if traceid is not None:
-            # FIXME This adds zeroes on the MS side until traceid is 128b long.
-            # Confirm that this is the desired implementation.
-            carrier[_TRACEID] = format(traceid, "032x")
+            traceid = format(traceid, "x")
+            carrier[_TRACEID] = "{}{}".format(
+                traceid, "0" * (32 - len(traceid))
+            )
         if spanid is not None:
             carrier[_SPANID] = format(spanid, "016x")
 
@@ -138,8 +139,9 @@ def extract(self, carrier):
                 baggage = None
 
         # FIXME This truncates the MSb of traceid until only 64b are left.
-        # Confirm that this implementation is correct.
-        traceid = traceid[-16:]
+        # This should only be done when reporting to LightStep. What exactly
+        # needs to be coded?
+        # traceid = traceid[-16:]
 
         return SpanContext(
             # traceid and spanid are encoded in hex, so thet must be encoded

tests/b3_propagator_test.py

@@ -28,7 +28,9 @@ def test_inject(self):
         self.assertEqual(
             carrier,
             {
-                "x-b3-traceid": format(span.context.trace_id, "032x"),
+                "x-b3-traceid": (
+                    format(span.context.trace_id, "x").ljust(32, "0")
+                ),
                 "x-b3-spanid": format(span.context.span_id, "016x"),
                 "checked": "baggage"
             }
@@ -42,7 +44,9 @@ def test_inject(self):
         self.assertEqual(
             carrier,
             {
-                "x-b3-traceid": format(span.context.trace_id, "032x"),
+                "x-b3-traceid": (
+                    format(span.context.trace_id, "x").ljust(32, "0")
+                ),
                 "x-b3-spanid": format(span.context.span_id, "016x"),
                 "x-b3-flags": 1,
             }