Speed-up happens before by using pandas logical operations.

xlap/analyse/latency.py

@@ -17,7 +17,6 @@ def _happens_before(df, a, b, config):
     """
     check if a happens-before b in the trace
     """
-    l = len(df[a])
     # check whether a and b occur in the same thread. If so, a and b cannot be
     # concurrent.
     ta = _get_thread_for_event(config, a)
@@ -25,23 +24,15 @@ def _happens_before(df, a, b, config):
     cname_a = str(a)[:-2] + "_C"
     cname_b = str(b)[:-2] + "_C"
     if (ta == tb and ta != None and tb != None):
-        for i in range(l):
-            tsa = df[a].iloc[i]
-            tsb = df[b].iloc[i]
-            if tsa > tsb:
-                return False
-            csa = df[cname_a].iloc[i]
-            csb = df[cname_b].iloc[i]
-            if tsa == tsb and csa > csb and csb != 0:
-                return False
-        return True
+        tg = df[a] > df[b]
+        if tg.any():
+            return False
+        df2 = df[df[a] == df[b]]
+        return not ((df2[cname_a] > df2[cname_b]) & df2[cname_b] != 0).any()
 
     # since a and b occur in different threads, we cannot compare cyclestamps.
     # If in doubt, a and b are concurrent.
-    for i in range(l):
-        if df[a].iloc[i] >= df[b].iloc[i]:
-            return False
-    return True
+    return not (df[a] >= df[b]).any()
 
 def _fast_happens_before(df, a, b, hb):
     """