This file was a performance test of sorts

1 files changed, 56 insertions, 0 deletions

diff --git a/perf/bug397.py b/perf/bug397.py
new file mode 100644
index 0000000..4d72e90
--- /dev/null
+++ b/perf/bug397.py
@@ -0,0 +1,56 @@
+#!/usr/bin/env python
+"""
+Run this file two ways under coverage and see that the times are the same:
+
+    $ coverage run lab/bug397.py slow
+    Runtime per example: 130.96 +/- 3.70 us
+    $ coverage run lab/bug397.py fast
+    Runtime per example: 131.34 +/- 4.48 us
+
+Written by David MacIver as part of
+https://bitbucket.org/ned/coveragepy/issues/397/stopping-and-resuming-coverage-with
+
+"""
+from __future__ import print_function
+
+import sys
+import random
+import time
+import math
+
+if sys.argv[1] == "slow":
+    sys.settrace(sys.gettrace())
+
+random.seed(1)
+
+
+def hash_str(s):
+    h = 0
+    for c in s:
+        h = (h * 31 + ord(c)) & (2 ** 64 - 1)
+    return h
+
+data = [
+    hex(random.getrandbits(1024)) for _ in range(500)
+]
+
+N_SAMPLES = 100
+
+
+def mean(xs):
+    xs = list(xs)
+    return sum(xs) / len(xs)
+
+
+def sd(xs):
+    return math.sqrt(mean(x ** 2 for x in xs) - mean(xs) ** 2)
+
+
+if __name__ == '__main__':
+    timing = []
+    for _ in range(N_SAMPLES):
+        start = time.time()
+        for d in data:
+            hash_str(d)
+        timing.append(1000000 * (time.time() - start) / len(data))
+    print("Runtime per example:", "%.2f +/- %.2f us" % (mean(timing), sd(timing)))