Update txtime_stats script to print a histogram to a file

scripts/txtime_stats.py

@@ -28,6 +28,16 @@ import math
 import sys
 
 def compute_offsets_stats(file_path):
+
+    measure_set = {}
+    measure_set["measure_type"] = "packet_jitter_tcpdump"
+    measure_set["props_names"] = ["packet_jitter_tcpdump"]
+    measure_set["units"] = ["us"]
+    measure_set["props_type"] = ["histogram"]
+    measure_set["metadata"] = {"i": interval}
+
+    histogram = [0 for i in range(0, 2000)]
+
     with open(file_path) as f:
         min_t = sys.maxsize
         max_t = -sys.maxsize
@@ -40,17 +50,32 @@ def compute_offsets_stats(file_path):
 
             if i > 0:
                 val = arrival_tstamp - prev_tstamp
+                jitter = (val - interval) / 1000
+                histogram_index = 1000 + jitter
+                if histogram_index < 0 or histogram_index > 2000:
+                    print("jitter too high: {}\n".format(jitter))
+                else:
+                    histogram[histogram_index]++
 
                 # Update statistics.
-                # Compute the mean and variance online using Welford's algorithm.
-                min_t = val if val < min_t else min_t
-                max_t = val if val > max_t else max_t
+                min_t = jitter if jitter < min_t else min_t
+                max_t = jitter if jitter > max_t else max_t
 
             i += 1
             prev_tstamp = arrival_tstamp
 
         if i > 0:
-            print("Jitter: " + str((max_t - min_t) / 1000) + "us")
+            print("Jitter: {}us".format(max_t - min_t))
+
+    measure_set["props"] = [histogram]
+
+    data = {}
+    data["measure_sets"] = [{measure_set}]
+
+    path = "tcpdump_histogram"
+
+    with open(path, 'w') as outfile:
+        json.dump(data, outfile)
 
 def main():
     parser = argparse.ArgumentParser()