Add adjustable offset to audit_period.

Allows audit periods to be offset, so daily periods can begin at local
midnight, instead of UTC, monthly periods can begin on the 15th
instead of the 1st, etc.

Fixes bug 948601

Change-Id: I38f6af0a5a513f888b791a4b9ca39467030105f2

1 files changed, 66 insertions, 17 deletions

diff --git a/nova/utils.py b/nova/utils.py
index 712242fd5..5b8eda012 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -373,38 +373,87 @@ EASIER_PASSWORD_SYMBOLS = ('23456789',  # Removed: 0, 1
 
 
 def current_audit_period(unit=None):
+    """This method gives you the most recently *completed* audit period.
+
+    arguments:
+            units: string, one of 'hour', 'day', 'month', 'year'
+                    Periods normally begin at the beginning (UTC) of the
+                    period unit (So a 'day' period begins at midnight UTC,
+                    a 'month' unit on the 1st, a 'year' on Jan, 1)
+                    unit string may be appended with an optional offset
+                    like so:  'day@18'  This will begin the period at 18:00
+                    UTC.  'month@15' starts a monthly period on the 15th,
+                    and year@3 begins a yearly one on March 1st.
+
+
+    returns:  2 tuple of datetimes (begin, end)
+              The begin timestamp of this audit period is the same as the
+              end of the previous."""
     if not unit:
         unit = FLAGS.instance_usage_audit_period
+
+    offset = 0
+    if '@' in unit:
+        unit, offset = unit.split("@", 1)
+        offset = int(offset)
+
     rightnow = utcnow()
     if unit not in ('month', 'day', 'year', 'hour'):
         raise ValueError('Time period must be hour, day, month or year')
-    n = 1  # we are currently only using multiples of 1 unit (mdragon)
     if unit == 'month':
-        year = rightnow.year - (n // 12)
-        n = n % 12
-        if n >= rightnow.month:
-            year -= 1
-            month = 12 + (rightnow.month - n)
-        else:
-            month = rightnow.month - n
-        begin = datetime.datetime(day=1, month=month, year=year)
-        end = datetime.datetime(day=1,
+        if offset == 0:
+            offset = 1
+        end = datetime.datetime(day=offset,
                                 month=rightnow.month,
                                 year=rightnow.year)
+        if end >= rightnow:
+            year = rightnow.year
+            if 1 >= rightnow.month:
+                year -= 1
+                month = 12 + (rightnow.month - 1)
+            else:
+                month = rightnow.month - 1
+            end = datetime.datetime(day=offset,
+                                    month=month,
+                                    year=year)
+        year = end.year
+        if 1 >= end.month:
+            year -= 1
+            month = 12 + (end.month - 1)
+        else:
+            month = end.month - 1
+        begin = datetime.datetime(day=offset, month=month, year=year)
 
     elif unit == 'year':
-        begin = datetime.datetime(day=1, month=1, year=rightnow.year - n)
-        end = datetime.datetime(day=1, month=1, year=rightnow.year)
+        if offset == 0:
+            offset = 1
+        end = datetime.datetime(day=1, month=offset, year=rightnow.year)
+        if end >= rightnow:
+            end = datetime.datetime(day=1,
+                                    month=offset,
+                                    year=rightnow.year - 1)
+            begin = datetime.datetime(day=1,
+                                      month=offset,
+                                      year=rightnow.year - 2)
+        else:
+            begin = datetime.datetime(day=1,
+                                      month=offset,
+                                      year=rightnow.year - 1)
 
     elif unit == 'day':
-        b = rightnow - datetime.timedelta(days=n)
-        begin = datetime.datetime(day=b.day, month=b.month, year=b.year)
-        end = datetime.datetime(day=rightnow.day,
+        end = datetime.datetime(hour=offset,
+                               day=rightnow.day,
                                month=rightnow.month,
                                year=rightnow.year)
+        if end >= rightnow:
+            end = end - datetime.timedelta(days=1)
+        begin = end - datetime.timedelta(days=1)
+
     elif unit == 'hour':
-        end = rightnow.replace(minute=0, second=0, microsecond=0)
-        begin = end - datetime.timedelta(hours=n)
+        end = rightnow.replace(minute=offset, second=0, microsecond=0)
+        if end >= rightnow:
+            end = end - datetime.timedelta(hours=1)
+        begin = end - datetime.timedelta(hours=1)
 
     return (begin, end)