test: Run negative ping tests in parallel

Rather than having to wait for each timeout sequentially, run each
test in parallel.

test/infamy/__init__.py

@@ -6,7 +6,7 @@ from .furl import Furl
 from .netns import IsolatedMacVlan
 from .sniffer import Sniffer
 from .tap import Test
-from .util import until
+from .util import parallel, until
 
 def std_topology(name):
     return os.path.realpath(

test/infamy/util.py

@@ -1,7 +1,35 @@
 import time
+import threading
 import infamy.neigh
 import infamy.netconf as netconf
 
+class ParallelFn(threading.Thread):
+    def __init__(self, group=None, target=None, name=None,
+                 args=(), kwargs={}, Verbose=None):
+        threading.Thread.__init__(self, group, target, name, args, kwargs)
+        self._exc, self._return = None, None
+
+    def run(self):
+        if self._target is not None:
+            try:
+                self._return = self._target(*self._args,
+                                            **self._kwargs)
+            except Exception as e:
+                self._exc = e
+
+    def join(self, *args):
+        threading.Thread.join(self, *args)
+
+        if self._exc:
+            raise self._exc
+
+        return self._return
+
+def parallel(*fns):
+    ths = [ParallelFn(target=fn) for fn in fns]
+    [th.start() for th in ths]
+    return [th.join() for th in ths]
+
 def until(fn, attempts=10, interval=1):
     for attempt in range(attempts):
         if fn():