Merge pull request #677 from tahoe-lafs/2266.remove-repeatable-random

Remove repeatable random test helper

Fixes: ticket:2266

src/allmydata/test/common_util.py

@@ -173,26 +173,10 @@ class ShouldFailMixin(object):
 
 
 class TestMixin(SignalMixin):
-    def setUp(self, repeatable=False):
-        """
-        @param repeatable: install the repeatable_randomness hacks to attempt
-            to without access to real randomness and real time.time from the
-            code under test
-        """
-        self.repeatable = repeatable
-        if self.repeatable:
-            import repeatable_random
-            repeatable_random.force_repeatability()
-        if hasattr(time, 'realtime'):
-            self.teststarttime = time.realtime()
-        else:
-            self.teststarttime = time.time()
+    def setUp(self):
         return super(TestMixin, self).setUp()
 
     def tearDown(self):
-        if self.repeatable:
-            import repeatable_random
-            repeatable_random.restore_non_repeatability()
         self.clean_pending(required_to_quiesce=True)
         return super(TestMixin, self).tearDown()
 

src/allmydata/util/repeatable_random.py

@@ -1,90 +0,0 @@
-"""
-If you execute force_repeatability() then the following things are changed in the runtime:
-
-1.  random.random() and its sibling functions, and random.Random.seed() in the random module are seeded with a known seed so that they will return the same sequence on each run.
-2.  os.urandom() is replaced by a fake urandom that returns a pseudorandom sequence.
-3.  time.time() is replaced by a fake time that returns an incrementing number.  (Original time.time is available as time.realtime.)
-
-Which seed will be used?
-
-If the environment variable REPEATABLE_RANDOMNESS_SEED is set, then it will use that.  Else, it will use the current real time.  In either case it logs the seed that it used.
-
-Caveats:
-
-1.  If some code has acquired a random.Random object before force_repeatability() is executed, then that Random object will produce non-reproducible results.  For example, the tempfile module in the Python Standard Library does this.
-2.  Likewise if some code called time.time() before force_repeatability() was called, then it will have gotten a real time stamp.  For example, trial does this.  (Then it later subtracts that real timestamp from a faketime timestamp to calculate elapsed time, resulting in a large negative elapsed time.)
-3.  The output from the fake urandom has weird distribution for performance reasons-- every byte after the first 20 bytes resulting from a single call to os.urandom() is zero.  In practice this hasn't caused any problems.
-"""
-
-import os, random, time
-if not hasattr(time, "realtime"):
-    time.realtime = time.time
-if not hasattr(os, "realurandom"):
-    os.realurandom = os.urandom
-if not hasattr(random, "realseed"):
-    random.realseed = random.seed
-
-tdelta = 0
-seeded = False
-def force_repeatability():
-    now = 1043659734.0
-    def faketime():
-        global tdelta
-        tdelta += 1
-        return now + tdelta
-    time.faketime = faketime
-    time.time = faketime
-
-    from allmydata.util.idlib import i2b
-    def fakeurandom(n):
-        if n > 20:
-            z = i2b(random.getrandbits(20*8))
-        elif n == 0:
-            return ''
-        else:
-            z = i2b(random.getrandbits(n*8))
-        x = z + "0" * (n-len(z))
-        assert len(x) == n
-        return x
-    os.fakeurandom = fakeurandom
-    os.urandom = fakeurandom
-
-    global seeded
-    if not seeded:
-        SEED = os.environ.get('REPEATABLE_RANDOMNESS_SEED', None)
-
-        if SEED is None:
-            # Generate a seed which is integral and fairly short (to ease cut-and-paste, writing it down, etc.).
-            t = time.realtime()
-            subsec = t % 1
-            t += (subsec * 1000000)
-            t %= 1000000
-            SEED = long(t)
-        import sys
-        sys.stdout.write("REPEATABLE_RANDOMNESS_SEED: %s\n" % SEED) ; sys.stdout.flush()
-        sys.stdout.write("In order to reproduce this run of the code, set the environment variable \"REPEATABLE_RANDOMNESS_SEED\" to %s before executing.\n" % SEED) ; sys.stdout.flush()
-        random.seed(SEED)
-
-        def seed_which_refuses(a):
-            sys.stdout.write("I refuse to reseed to %s.  Go away!\n" % (a,)) ; sys.stdout.flush()
-            return
-        random.realseed = random.seed
-        random.seed = seed_which_refuses
-        seeded = True
-
-    import setutil
-    setutil.RandomSet.DETERMINISTIC = True
-
-def restore_real_clock():
-    time.time = time.realtime
-
-def restore_real_urandom():
-    os.urandom = os.realurandom
-
-def restore_real_seed():
-    random.seed = random.realseed
-
-def restore_non_repeatability():
-    restore_real_seed()
-    restore_real_urandom()
-    restore_real_clock()