Sync charm-helpers

Change-Id: I96674f2d5a8573a5e6fc4800108adca74bdd406c

charmhelpers/contrib/hahelpers/cluster.py

@@ -27,6 +27,7 @@ clustering-related helpers.
 
 import subprocess
 import os
+import time
 
 from socket import gethostname as get_unit_hostname
 
@@ -45,6 +46,9 @@ from charmhelpers.core.hookenv import (
     is_leader as juju_is_leader,
     status_set,
 )
+from charmhelpers.core.host import (
+    modulo_distribution,
+)
 from charmhelpers.core.decorators import (
     retry_on_exception,
 )
@@ -361,3 +365,29 @@ def canonical_url(configs, vip_setting='vip'):
     else:
         addr = unit_get('private-address')
     return '%s://%s' % (scheme, addr)
+
+
+def distributed_wait(modulo=None, wait=None, operation_name='operation'):
+    ''' Distribute operations by waiting based on modulo_distribution
+
+    If modulo and or wait are not set, check config_get for those values.
+
+    :param modulo: int The modulo number creates the group distribution
+    :param wait: int The constant time wait value
+    :param operation_name: string Operation name for status message
+                           i.e.  'restart'
+    :side effect: Calls config_get()
+    :side effect: Calls log()
+    :side effect: Calls status_set()
+    :side effect: Calls time.sleep()
+    '''
+    if modulo is None:
+        modulo = config_get('modulo-nodes')
+    if wait is None:
+        wait = config_get('known-wait')
+    calculated_wait = modulo_distribution(modulo=modulo, wait=wait)
+    msg = "Waiting {} seconds for {} ...".format(calculated_wait,
+                                                 operation_name)
+    log(msg, DEBUG)
+    status_set('maintenance', msg)
+    time.sleep(calculated_wait)