add mt_api library

pythonlibs/mt_api/retryloop.py

@@ -0,0 +1,38 @@
+# retry loop from http://code.activestate.com/recipes/578163-retry-loop/
+import time
+import sys
+
+
+class RetryError(Exception):
+    pass
+
+
+def retryloop(attempts, timeout=None, delay=0, backoff=1):
+    starttime = time.time()
+    success = set()
+    for i in range(attempts): 
+        success.add(True)
+        yield success.clear
+        if success:
+            return
+        duration = time.time() - starttime
+        if timeout is not None and duration > timeout:
+            break
+        if delay:
+            time.sleep(delay)
+            delay *= backoff
+
+    e = sys.exc_info()[1]
+
+    # No pending exception? Make one
+    if e is None:
+        try:
+            raise RetryError
+        except RetryError as exc:
+            e = exc
+
+    # Decorate exception with retry information:
+    e.args = e.args + ("on attempt {0} of {1} after {2:.3f} seconds".format(
+        i + 1, attempts, duration), )
+
+    raise e